In 2001, we developed a video camera of 1,000,000 fps with an in-situ storage image sensor (ISIS). The performance is briefly explained at first. We are now developing innovative technologies to provide the ultra-high-speed video camera with higher level of performance and more useful functions, including the combined triple-ISIS camera, the built-in video trigger system, and the terraced image sensor. Their concepts are explained together with the expected performance.

The Great Russian physicist Academician A.M. Prokhorov passed away on the 8th of January 2002 in Moscow. He was born in Australia (Atorton Town) on the 11th of July 1916. Together with Academician N.G. Basov and Prof. C.H. Townes in 1964, he received the Nobel Prize in physics for discovery the fundamental operational principles of the LASER (Light Amplification by Stimulated Emission and Radiation). Among the great variety of scientific and technological areas to which Academician A.M. Prokhorov had devoted his extraordinary talent and his encyclopedical knowledge in physics, is the ultrafast photoelectronics and in particular image-converter high-speed photography. As early as at the beginning of the sixties, he clearly realized the importance and valuability of ultrafast image tubes application for gaining direct visual information in laser research. It was Academician A.M. Prokhorov who had initiated the image tube photography development specially oriented for laser investigations, providing steadily improvement of its time resolution starting from subnanosecond level in the sixties of the 20th Century down to subfemtosecond level at the beginning of the 21st Century. The new area of high-speed research, known as Femto-Attosecond Photoelectronics, is now established as the outstanding result of his imaginative efforts. In this memorial lecture some important achievements in the ultrafast photoelectronics attained under Academician A.M. Prokhorov supervision will be pointed out. Memorized are some perspective targets in high-speed image-converter photography to which Academician A.M. Prokhorov has been concerned during the last period of his brilliant and creative life.

Since "Recent progress on high speed photography and photonics in China" was presented in 21^st ICHSPP, several opto-mechanical high-speed cameras, image converter streak cameras and frame cameras, a velocity interferometer system for any reflector (VISAR), and a six degree-of-freedom measurement system of wind tunnel balance based on holographic lens have been developed in China, but our main efforts have spent on application of high speed photography and research on photonics, especially on ultrashort laser pulse generation and diagnosis of ultrafast phenomena. This paper gives a brief survey on some major progress of high-speed photography and photonics in China during past decade.

As a "son" of Beaune it seems appropriate to give a short appreciation of the work of Marey, as a pioneer in the field of high speed and motion recording photography, at this Congress held in his birthplace. Not only was he a notable physicist but he was a very often under appreciated pioneer of scientific photography, especially as applied to motion recording and analysis. It can be rightfully claimed that his work makes him an important element in the discovery of cinematography in general. His contemporary (and at times collaborator) Muybridge seems to have been credited with much of the acclaim in this field, possible because of his more extrovert character, and possible because of Marey's many other notable scientific achievements. Marey had invented a high-speed camera capable of 700 pps by 1894!

We have developed a high-speed gated, high-resolution digital intensified CCD (D-ICCD) camera. This camera consists of a highly sensitive, high-speed gated image intensifier (UV to infrared image intensifier or X-ray image intensifier) coupled to a digital CCD camera via a fiber optic plate (or relay lens). This camera has an IEEE 1394 interface for control and data transfer to a computer system and also has the following features: wide spectral response (from X-ray to infrared spectral range by using an X-ray image intensifier and an image intensifier with a GaAsP/GaAs photocathode), high-speed gating (20 ns to 10 ms gate width), and high resolution digital CCD camera (1280 x 1024 pixels). This camera will prove a useful tool for high-speed imaging and low-light-level imaging such as biological imaging when coupled with an optical microscope and non-destructive image diagnostics using an X-ray source.

Light emitting diodes are very efficient sources of visible and infared light. They have small size and can be combined with fiber optical cables easily. Simple videography can use the wavelength range 400 nm - 1000 nm, which is covered totally by the LED. The speed of modern LED allows flashes shorter than 100 ns in the whole spectral range.

We have developed an ultra high-speed video camera announced by Etoh at the 24^th ICHSPP. This new camera can capture 100 continuous images with a frame rate of up to 1,000,000 frames per second (fps). It comprises a new developed single-chip CCD image sensor called In-situ Storage Image Sensor (ISIS). The spatial resolution is 312 x 260 pixels and this high resolution is kept even at the maximum frame rate. This camera enables us to observe the fast phenomena, which could not be seen before. The principle of this system and some applications are introduced.

The information approach was applied to a determination of the actual properties of CCD-cameras. This approach is very useful when we have to establish from spectrograms, interferograms, holograms or other recorded data a set of functions that describe how the object under investigation behaves in space and time. Moreover this approach allows the actual properties of the measuring device be taken into account in order to determine the lower bound of experimental errors both before and after the measurement and to check how much use is made of the information that is contained in the recorded data. One of the best professional-quality CCD-cameras (ST-7I, Santa Barbara Instrument Group) was chosen for experimental investigation. Both the transfer (spread) function and the frequency-contrast function of this CCD-camera were determined experimentally and the optical channel fluctuation noise and the signal-to-noise ratio were measured as well. It has been shown that due to light scattering in the semiconductor base of the CCD matrix the amplitudes of high spatial frequency components of the image are reduced; the smaller the frequency of the light, the smaller are the amplitudes of the spatial frequency components of the output image. It has been ascertained that the relative error of the recorded image can be as small as one percent if the whole of the dynamic range is used (the full well capacity is equal to 40,000e) and if the highest spatial frequency of the image is small enough. But if the highest spatial frequency of the image f_c is limited by pixel steps Δ (Δ approximately equals ½f_c ), the relative error increases due to contrast reduction of the high spatial frequency and the relative error of the reconstructed input intensity distribution of the image more than doubles. This experimental result is very close to that derived from the calculated output image information. These experimental and simulation results are illustrated by recently obtained data.

A 1 M fps video camera was applied to the observation of drop impacts onto water surfaces. It captured the detailed mechanism of sheet ejection from the contact region between the drop and the water surface, the small droplets separated from the ejected sheet and bubble entrapment by a drop impacting onto a water surface. The 103 consecutive images are enough to form a short movie which is suitable for dynamic recognition.

We present an image sensor dedicated to the analysis of fast moving luminous objects. The circuit is fabricated in standard 0.6 μm CMOS technology with an image sensing array of 64 x 64 pixels. Its working principle is as follows: An electronic unit integrated at the pixel level measures the elapsed time since the beginning of the acquisition till the passage of the luminous object in front of the pixel under consideration. This value that corresponds to a number of clock cycles is stored in a 4-bit memory at the pixel level and translated into a gray level, the brighter ones corresponding to the shortest time. The result is a 16-gray level image that represents the trajectory and direction of motion of the object. Knowing the frequency of the clock, the distance between the pixels and the difference in gray levels of the pixels, the speed of the moving object can be determined. Alternatively, the 16-gray level image can be considered as a superposition of 16 one gray level images that represent the 16 positions of the moving object at 16 different time instances in the course of its displacement. The frequency of the clock can be as high as 20 MHz for the analysis of very high speed phenomena. The working principle and the architecture of the image sensor will be described in details in this paper. Moreover, the results of the tests carried out on the circuit, namely the analysis of the movement of the spot on an oscilloscope screen, will also be reported and the potential applications of the image sensor discussed.

A high speed camera has been developed by Optronis GmbH for recording fast moving objects with high spatial resolution, high repetition rate and short exposure time. The camera offers variable frame to frame delay times. The structural principal and performances of the instrument are discussed.

We introduce a development method and its result based on 'platform architecture' to reduce development time and cost. For evaluating this method, a digital high-speed video camera, which can be operated at 2,000 frames per second (FPS) with 1M-pixels resolution and up to over 100,000 FPS with reduced resolution, has been developed using the platform architecture. First, we show technology improvements for high-speed image sensors and high-speed video cameras and discuss customer requirements. Next, functional structures based on the platform architecture are shown. For this high-speed video camera, a CMOS image sensor, which has high sensitivity and can be driven at 2,000FPS with full resolution of 1024 by 1024 pixels (1M-pixels), has also been developed. In addition, another high-speed video camera, which has 512 by 512 pixels with 2000FPS, has been developed following the above camera using the same "platform" and most of its components. We describe technical specifications of these high-speed video cameras for the results.

A method is proposed for reconstructing the distribution of charged particles emitted by a nonstationary source over the initial velocity projections and escape time. The method involves recording time-integrated images of a nonstationary source on a 2D screen with spatial resolution. Reconstruction of model distributions is analyzed in simulations. The conditions of modeling experiments are found, which provide a stable reconstruction based on the method proposed.

Sensitivity of IR imaging systems based on a planar semiconductor-gas discharge (SGD) cell is considered. These systems feature conversion of IR images into visible ones with the response time on the microsecond scale. A converted (visible) image at the cell output is captured by an image sensor coupled to the cell either with a lens or with a fiber optic taper. Comparison of both methods shows that fiber tapers can provide much higher ultimate coupling efficiency but has less flexibility in usage and bring in a high additional heat load on the cooling unit. Obtained equations allow calculation of sensitivity for the whole system, taking into account such parameters of its constituents as the conversion efficiency and dark current density of the IR converter cell, readout noise of the image sensor, light transfer efficiency from the cell to the sensor, as well as the equivalent pixel area in the gas discharge plane and the exposure duration. The equations are applied to evaluate sensitivity of the IR imaging system utilizing a SGD cell filled with argon, where a Si:Zn semiconductor sensitive in a spectral range of 1.1 - 3.5 μm is used. The results demonstrate the possibility of achieving quite a high sensitivity performance of considered systems.

In order to analyze mechanism of melting and deformation of metal while it is being rapidly heating, or a combusion process, it is important not only to measure the time displacement of a sample and its acceleration, but to measure the change in the temperature distribution of the sample over time. For this purpose, we have developed a new Multi-Spectral Optics. By mounting combining a high-speed camera with our Multi-Spectral Optics system, we have successfully acquired a temperature distribution map and its color image simultaneously. In our system, a color image is composed with three spectrum images from wavelengths, 450 nm, 550 nm and 750 nm. A temperature distribution map can be created from two images in the near infra-red wavelengths, 750 nm and 850 nm, which were obtained by applying the ratio temperature pyrometry method. However, in order to observe and analyze rapid deformation of a sample, it is important to capture vivid images in color. This task requires additional external light. Since a high intensity of emitted light will cause an error in temperature, it is very difficult correctly to measure temperature and deformation of the sample at the same time. Temperature measured with near infra-red lights is not be influenced by the external surrounding light. In particular, for taking photos of welding phenomena, it is possible to capture clear images with excessive lighting without affecting temperature measurement. Moreover, in combustion phenomenon, it is possible to avoid the influence of chemiluminescence caused by radicals such as C₂ in flame.

4DVideo is creating a general purpose capability for capturing and analyzing kinematic data from video sequences in near real-time. The core element of this capability is a software package designed for the PC platform. The software ("4DCapture") is designed to capture and manipulate customized AVI files that can contain a variety of synchronized data streams -- including audio, video, centroid locations -- and signals acquired from more traditional sources (such as accelerometers and strain gauges.) The code includes simultaneous capture or playback of multiple video streams, and linear editing of the images (together with the ancilliary data embedded in the files). Corresponding landmarks seen from two or more views are matched automatically, and photogrammetric algorithms permit multiple landmarks to be tracked in two- and three-dimensions -- with or without lens calibrations. Trajectory data can be processed within the main application or they can be exported to a spreadsheet where they can be processed or passed along to a more sophisticated, stand-alone, data analysis application. Previous attempts to develop such applications for high-speed imaging have been limited in their scope, or by the complexity of the application itself. 4DVideo has devised a friendly ("FlowStack") user interface that assists the end-user to capture and treat image sequences in a natural progression. 4DCapture employs the AVI 2.0 standard and DirectX technology which effectively eliminates the file size limitations found in older applications. In early tests, 4DVideo has streamed three RS-170 video sources to disk for more than an hour without loss of data. At this time, the software can acquire video sequences in three ways: (1) directly, from up to three hard-wired cameras supplying RS-170 (monochrome) signals; (2) directly, from a single camera or video recorder supplying an NTSC (color) signal; and (3) by importing existing video streams in the AVI 1.0 or AVI 2.0 formats. The latter is particularly useful for high-speed applications where the raw images are often captured and stored by the camera before being downloaded. Provision has been made to synchronize data acquired from any combination of these video sources using audio and visual "tags." Additional "front-ends," designed for digital cameras, are anticipated.

In this paper, a new application system with high speed photography, i.e. an observational system for the tele-micro-operation, has been proposed with a dynamic focusing system and a high-speed image processing system using the "Depth From Focus (DFF)" criteria. In micro operation, such as for the microsurgery, DNA operation and etc., the small depth of a focus on the microscope makes bad observation. For example, if the focus is on the object, the actuator cannot be seen with the microscope. On the other hand, if the focus is on the actuator, the object cannot be observed. In this sense, the "all-in-focus image," which holds the in-focused texture all over the image, is useful to observe the microenvironments on the microscope. It is also important to obtain the "depth map" which could show the 3D micro virtual environments in real-time to actuate the micro objects, intuitively. To realize the real-time micro operation with DFF criteria, which has to integrate several images to obtain "all-in-focus image" and "depth map," at least, the 240 frames par second based image capture and processing system should be required. At first, this paper briefly reviews the criteria of "depth from focus" to achieve the all-in-focus image and the 3D microenvironments' reconstruction, simultaneously. After discussing the problem in our past system, a new frame-rate system is constructed with the high-speed video camera and FPGA hardware with 240 frames par second. To apply this system in the real microscope, a new criterion "ghost filtering" technique to reconstruct the all-in-focus image is proposed. Finally, the micro observation shows the validity of this system.

We present here a new paradigm based on a centralized architecture to realize electronic artificial retina. This original architecture, named connectionist retina, can execute in real time RBF and MLP neural networks applications. We demonstrate that this intelligent embedded system could be used for vision applications. We describe here the realized prototype system.

The new technologies that are CMOS sensors and most recent FPGA platform like the Xilinx Virtex-II family allow the realization of totally digital active video sensors. On the other hand, the digital visual interface (hereinafter DVI) specification provides a high-speed digital connection for visual data (T.M.D.S). These various technologies led us define a frame grabber -- processing -- display system based on three components: a CMOS sensor PB-MV13 of Photobit, a FPGA platform Virtex-II from Xilinx and a T.M.D.S transmitter SiI 160 of Silicon Image. An advantage of this realization is the suppression of the various analogue-digital conversion stages generally used to digitize and restore the video stream. The reconfiguration of the FPGA platform is another advantage, which does not limit processing to a particular purpose and simplify the conception. Besides, an important constraint of this realization is the frame definition 1280 x 1024 (SXGA) and the rate of 60 images per second with a pixel frequency of 108 MHz.

Digital image processing algorithms are usually designed for the raw format, that is on an uncompressed representation of the image. Therefore prior to transforming or processing a compressed format, decompression is applied; then, the result of the processing application is finally re-compressed for further transfer or storage. The change of data representation is resource-consuming in terms of computation, time and memory usage. In the wide format printing industry, this problem becomes an important issue: e.g. a 1 m² input color image, scanned at 600 dpi exceeds 1.6 GB in its raw representation. However, some image processing algorithms can be performed in the compressed-domain, by applying an equivalent operation on the compressed format. We investigate the application of compression to the Wide Format Document management chain and more specifically to the image processing components. We survey the typical printing processing operations, such as rotation by multiple 90°, symmetry along vertical or horizontal axis or scaling in the JPEG compressed-domain.

We present an investigation that has been carried out on the design of a high speed scanning system for a data storage application. Polypeptide material is used to store data by the angular multiplexing process. This material presents many advantages compared with others. To address the optical memory, our set-up is composed of micro-scanning mirrors (MEMS) and an acousto-optic deflector (AOD). This association leads to an addressing set-up with a very good performance in terms of the access time and the angular bandwidth. Expermental tests made with micro-scanning mirrors (MEMS) of 3 x 3 mm² are described. Problems fo synchronization between the different elements and the influences of MEMS deformation are also discussed.

Although mechanically simple, centrifugal spreaders used for mineral fertilization involve complex physics that cannot be fully characterized at the present time. To avoid fertilizer misadjustments in the field, centrifugal spreading, and especially the initial conditions of flight of the granules, have to be accurately understood. The work described in this paper led to the conception of a high speed images collection system for characterizing the centrifugal spreading in a laboratory. This patented multiexposure system allows to determine granule trajectories after their ejection, with the use of a high resolution low cost digital camera, combined with a set of flashes, and different motion estimation methods. The Markov Random Fields (MRFs) method gives very accurate and better results in comparison with intercorrelation or theoretical modeling of the granule throws methods. This establishment allows to use the results in ballistic model to predict the fertilizer repartition on the ground. A fourth motion estimation method based on Gabor filters is moreover currently investigated.

In this article, an image processing method to detect automatically maturity spots on apples in order to assess their maturity state, is presented. Two different techniques of segmentation are studied. The first one is mono dimensional and looks for the maxima in a sequence of pixels. The other one is a morphological technique called the watershed algorithm. The advantages and the drawbacks of the two techniques are compared. These both approaches are particularly adapted to spot detection but they are sensitive to noise and often provide an over-segmentation. To overcome this difficulty we propose a multi-scale analysis based on adjacency graph pyramid. This method has the advantage of providing a unique segmentation, which does not depend on the order of the regions scanning. The merging will be driven by criteria of a model describing spot characteristics. Experimental results have been obtained on a set of 1200 images of apples, showing the interest of the method.

Laser Doppler flowmetry is a non-invasive method used in the medical domain to monitor the microvascular blood cell perfusion through tissue. Most commercial laser Doppler flowmeters use an algorithm calculating the first moment of the power spectral density to give the perfusion value. Many clinical applications measure the perfusion after a vascular provocation such as a vascular occlusion. The response obtained is then called reactive hyperaemia. Target pathologies include diabetes, hypertension and peripheral arterial occlusive diseases. In order to have a deeper knowledge on reactive hyperaemia acquired by the laser Doppler technique, the present work first proposes two models (one analytical and one numerical) of the observed phenomenon. Then, a study on the multiple scattering between photons and red blood cells occurring during reactive hyperaemia is carried out. Finally, a signal processing that improves the diagnosis of peripheral arterial occlusive diseases is presented.

The LIL which is under construction at the French Atomic Energy Commission CESTA center is an 8 beam facility -- 60 kJ @ 0.35 μm -- dedicated to laser matter interaction experiments. This facility is now in the last construction phase and the first experiments have already been conducted in order to demonstrate the performances of both front end and multipath high energy section at 1.05 μm. The experiments that were recently conducted have demonstrated the efficiency of the 4 pass and L-turn amplification concept, and already show that the expected output intensity performance at 1w has been reached. Moreover, these experiments have confirmed the capability of our laser simulation code (Miro) to predict this laser output performance. We are currently implementing the 1w/3w conversion and focusing system, which combines for each beam a large 1w grating associated with KDP/DKDP frequency doubler and tripler and a large 3w (0.35 μm) focusing grating. Focal spot size will be available in the 0.5 to 4 mm range with either a circular or elliptical spatial profile. LIL will also support the beam smoothing capability (longitudinal or transverse). The 1w section is currently under tests at the kJ level, and 3w tests will be performed very soon. The LIL prototype facility is the first step of the French Atomic Energy Commission program toward the construction of the 240 beam Laser Megajoule (LMJ) facility which will enable us to conduct high energy density experimental program in the 640 TW @ 2 MJ range before the end of this decade.

Hydrodynamic instability in laser-irradiated targets have been investigated in detail by using ultra high-speed x-ray radiographic technique. Recently developed high-resolution x-ray imaging for laser-driven Rayleigh-Taylor (RT) instability experiments as well as data including RT growth rate, ablation density and plasma density profile are desribed. Results are of great importance for comprehensive understanding of the dispersion relation of the laser-driven RT instability. Especially, direct observation of the ablation density was first achieved with temporal and spatial resolutions of 100 ps and 3 μm, respectively. Imaging techniques includes x-ray Moire imaging, x-ray penumbral imaging and Fresnel phase zone plate imaging coupled with x-ray streak cameras or x-ray CCD cameras. Experiments were performed by using Gekko-XII/HIPER laser system at the Institute of Laser Engineering, Osaka University.

This paper gives an overview of works undertaken at CEA/DIF in high speed cinematography, optoelectronic imaging and ultrafast photonics for the needs of the CEA/DAM experimental programs. We have developed a new multichannel velocimeter, and a new probe for shock breakout timing measurements in detonics experiments. A brief description and a recall of their main performances will be made. We have implemented three new optoelectronic imaging systems, in order to observe dynamic scenes in the ranges of 50 - 100 keV and 4 MeV. These systems are described, their main specifications and performances are given. Then we describe our contribution to the ICF program: after recalling the specifications of LIL plasma diagnostics, we describe the features and performances of visible streak tubes, X-ray streak tubes, visible and X-ray framing cameras and the associated systems developed to match these specifications. At last we introduce the subject of components and systems vulnerability in the LMJ target area, the principles identified to mitigate this problem and the first results of studies (image relay, response of streak tube phosphors, MCP image intensifiers and CCDs to fusion neutrons) related to this subject. Results obtained so far are presented.

The CEA has studied a unique picosecond timing system for the Laser Integration Line (L.I.L.), an 8-beam laser currently under construction in France. This laser is the prototype of a future facility dedicated to inertial confinement fusion. It requires very precise timing between its laser beams and ultra-fast diagnostics. Its timing system had to achieve unprecedented performances: to deliver 800 trigger signals over distances exceeding 300 m with delays individually programmable and near-picosecond range time accuracy. To achieve this goal, the CEA developed a new design based on very accurate electrical delay generators connected to a master clock through a bi-directional fiber-optic time distribution network. In this article, we describe its principle and present achieved performances.

The Vulcan Nd:glass laser at the Central Laser Facility (CLF) has recently been upgraded to the Petawatt level (10¹⁵ Watts). The three year upgrade project was contracted to deliver 500 J in a near diffraction limited pulse of 500 fs duration. The Petawatt facility will deliver an irradiance on target of 10²¹ W•cm^-2 for a wide ranging experimental program in fundamental physics and advanced applications. This includes the interaction of super-high intensity light with matter, fast ignition fusion research, photon induced nuclear reactions, electron and ion acceleration by light waves and the exploration of the exotic world of plasma physics dominated by relativity. Of particular relevance to high speed photography, the Petawatt beam will be used to create a source for advanced high-speed imaging using protons, neutrons and X-rays on an hitherto inaccessible time-scale.

This paper presents an overview of electromagnetic compatibility (EMC) management for fast diagnostic design. In research centers, we often use prototypes or very specific diagnostics which exist in very few small number. Technical specifications are close to physical limits or hard to reach. It takes a considerable effort to put them in working order. Often, there is no real expertise on EMC. However, electromagnetic interference (EMI) could ruin the system. At best, it will decrease the signal to noise ratio. In the worst cases, the diagnostic will not work or could be destroyed. Generally, EMI occurs when an electrical disturbance from either natural phenomena (electrostatic discharge, lightning, and so on) or electronic equipment causes an undesired response in another piece of equipment. EMC is just the opposite of EMI; that is, EMC is said to exist when no equipment or system causes EMI to other equipment or systems. The three elements of an EMI episode are the source, the victim, and the coupling path. We will present and detail the classical approach in EMC. This approach can be successfully applied for installations where a single engineering entity has the authority to prescribe and enforce a certain compatibility level. We illustrate this approach with an example: EMC on plasma diagnostics in a 10 - 60 kiloJoule class laser. Up to now, all the diagnostics developed for laser produced plasmas have mainly been designed without taking into account the direct effects of radiated energies emitted by the plasma itself on the diagnostic active components. Our laser facility, the LIL, will be able to focus up to 60 kJ into a volume of less than 1 mm³. We have to evaluate the electromagnetic pulse (EMP) inside and outside the target chamber where diagnostics, cables and oscilloscopes will be installed. We performed experiments at the Omega laser facility at the University of Rochester. We designed a specific electromagnetic probe for pulse measurement with a rise time down to 100 ps. We will discuss problems induced by the grounding approach and show how to cope with them.

The CEA is responsible for the Megajoule Laser (LMJ) facility. This facility is a large Flashlamp pump laser (1.8 MJ optical output). CEA entered into a contract with THALES to carry out the pulsed power conditioning system for the Megajoule Laser. The pulsed power conditioning system has a modular design which makes the facility more flexible and safer. This complete primary storage is a 450 MJ energy capacitor bank composed of 270 modules of 1.6 MJ energy. Each module is a stand-alone capacitor bank equipped with twelve 100 kJ capacitors and its embedded control/monitor and diagnostic system which is connected by an optical Ethernet link to the Command Control Supervisor of the facility. In the first step of the LMJ program, called "Line Integration Laser" (LIL), one laser chain will be built. The capacitor bank used to drive the LIL is comprised of 10 modules. This paper describes the design of the modules and the results of testing. The overall electrical performance meets the requirements.

A high speed differential interferometry based photography system was used to visualize the flow around a missile equipped with a forward directed spike mounted at the missile's nose. Pressure and temperature on the hemispherical surface of the nose can be substantially reduced by a forward facing spike. Both experiments and computations were carried out to study the flowfield around three-dimensional blunt bodies operated with a spike for a large range of angles of attack at a Mach number of 4.6. A blunt body, a classical disc-tipped spike, a sphere-tipped spike and a biconical-tipped spike have been studied. The experiments involved high-pressure shock tunnel investigations using the shock tube facility of ISL. The differential interferometry techniqe (DI) was used to visualize the flowfield around the different missile spike geometries. A series of eight flow pictures was obtained with the use of a multi-spark light source and a drum camera with rotating film. Steady-state 3D Navier-Stokes computations were carried out to predict the flow field around the spike-tipped missile. DI flow pictures were used to verify the numerical results of the computational calculations. Thus, reliable theoretical results are now available which point out the advantages/disadvantages of the spike geometries under investigation in comparison with the blunt body, especially with regard to drag reduction.

An ultra-high-speed camera system operating at up to 1 MHz is presented using a diode-pumped solid state laser at 532 nm operating between 1 and 100 kHz. Images are taken with a high-resolution high-speed CCD-camera capable of recording 4 or 16 images up to 1280 x 1024 pixel at a frame-rate of up to 1 MHz. The system can be used for various high-speed visulalization purposes. A turbulent air flow at velocities of a few m/s was recorded and PIV vector fields computed. From consecutive vector fields the local acceleration field was derived. Gasoline direct injection sprays were recorded at up to 80 kHz frame rate.

A comparison between the steady and unsteady two-phase air/fuel flow through an internal combustion engine intake valve has been studied experimentally in a specially designed rig. The atomization of liquid fuel film flows aroud the valve gap and its subsequent impingement onto the neighboring walls can readily be seen. Similarities in the flow patterns between steady and unsteady modes of valve and injector operation are also apparent. The effects of altering the injection timing for the unsteady case shows that injection prior to valve opening yields a considerable increase of fuel impingement within the chamber beneath the valve. A brief description of the base airflow is also given alongside the two-phase data.

The propagation of blast waves is strongly influenced by atmospheric conditions. The effect of non-uniform temperature distribution on the blast wave propagation in the atmosphere is investigated at the Shock Wave Research Center (SWRC), Institute of Fluid Science, Tohoku Univ. The temperature difference of five degrees in the vertical direction is created in the 1000 mm x 700 mm explosion box, in which the spherical blast waves are generated by igniting 10 mg of AgN₃ pellet. The propagations of blast waves are successfully observed and visualized by using double exposure holographic interferometory.

The aim in this paper is clarification of the role of shock waves in compressible turbulent flows by comparing shock wave interaction with baffle plates of a solid and a rigid porous materials. As the basic research for this purpose, experimental investigation of the shock wave attenuation over solid and rigid porous baffle plates is presented. These models with two different heights are installed in 60 mm x 150 mm diaphragmless shock tube. Observations of double exposure holographic interferometry and pressure measurements at several points are carried out. The difference of shock wave attenuation over these models can be clarified.

We report the experimental generation and characterization of a 160-GHz picosecond pulse train using multiple four-wave mixing temporal compression of an initial dual frequency beat signal in the anomalous-dispersion regime of a non-zero dispersion shifted fiber. The propagation of the initial beat signal was first analyzed using several numerical simulations. The fiber parameters were then measured thanks to a technique based on modulation instability (MI) and finally, the generated 160-GHz pulse train was characterized with a frequency-resolved optical gating (FROG) setup.

The MegaSun high intensity illumination system has been developed for ultrahigh-speed imaging applications that previously required argon candles (argon bombs) for adequate illumination. This plasma discharge system has produced excellent color images of explosive tests taken by various Cordin cameras operating up to two million frames per second with small stops (125 ns exposure). Exposure times of 10 ns to 50 ns were easily achieved with a variety of intensified electronic cameras. For tests involving explosives, the non-destructive nature of the lamps facilitates new test arrangements -- for example, the large standoff distances associated with destructive argon candles are no longer necessary. For the wider test community that does not use explosives, this benign, yet intense, light source generates the illumination necessary to use these ultrahigh-speed cameras to acquire superb color images. This paper will briefly review the mechanical, electrical, and optical characteristics of the MegaSun system, and then illustrate its capabilities with a variety of images from live tests.

An Anti-Resonant Ring (ARR) structure was introduced to a conventional passively solid-state Q-switched Nd:YAG laser for the first time. Using a plane-ARR critical resonator, and Cr⁴⁺:YAG crystal, BDN dye film and color centered LiF:F^-₂ crystal as saturable absorber. High energy and high stability single Q-switched pulse with the output energies range from 101.6 - 82.5 mJ and stabilities range from 99.2 - 98.6% were obtained respectively. The experimental results were analyzed well by using the mechanism of the transient grating effect generated by ARR structure.

Interference upon temporal overlap of two ultrashort pulse laser beams (80 - 100 fs) in a wide bandgap material (BaF₂) instantaneously creates an index grating via the optical Kerr effect. This grating causes the diffraction both of the generating beams as well as of further incident beams with an overall efficiency of > 23%. Strong third harmonic generation is observed with an efficiency of up to approximately 3% due to an automatic self phase-matching process. The introduction of a third beam leads to a diffraction pattern simulating digital logic gates (e.g. decoder, demultiplexer, AND-and OR-logic), demonstrating the possibility of simple logic operations on a femtosecond time scale

For reaching temporal resolution of about 1 fs in a time converting chronography of pulsed photon radiation in a range of visible light a new principle in the chronography consisting in simultaneous acceleration and longitudinal modulation of photoelectrons for the shortest time (about 1 ps) and at the moment of their escaping from a photocathode are proposed and considered. Photoelectron camera realizing the new principles and using the gold photocathode for soft-x-ray pulse registration with temporal resolution of 100 fs at the photoelectron bunch population of about 1000 electrons will be also discussed.

We frequently measure velocity-time histories of dynamic experiments. In some, the Doppler-shifted light is often weak compared to non-shifted light reflected from stationary surfaces and imperfections in components. With our Fabry-Perot (FP) based systems which handle multiple frequencies, data is lost where the fringes coincide; if we had used an intensity-measuring VISAR system, it would probably fail. We designed a facility for doing experiments under such conditions by selectively eliminating most of the non-shifted light. Our first filter excluded non-shifted light by a factor of 300 when manually tuned, and by 150 when run in an auto-tuning mode. It used a single 50 mm diameter FP as the filter with a spacing of 1.65 mm and reflectivities of 77%, and filters five channels prior to use in one of our 5-beam velocimeters. One use of the filter system was to embed optical fibers in long sections of explosives to make continuous detonation velocity-time histories. We have carried out many such tests with this filter, and two without. A special single-beam filter was constructed with a 40% efficiency for shifted light that rejected non-shifted light by 4 million times, with a bandpass of a few GHz.

When brittle materials break under external force, fast propagating cracks appear often whose propagation speed is from 200 m/s to 2000 m/s. The fast propagating cracks suddenly bifurcate into two cracks when the propagation speed is high enough. But the mechanism of the rapid crack bifurcation has not been well understood. In the present study, two optical systems of pulsed holographic microscopy are applied to take photographs of rapidly bifurcating cracks in PMMA plate specimens. The cracks are of the opening mode and propagate at a speed more than 600 m/s. The photographs of the cracks are simultaneously taken on the both sides of the plate specimens about 10 μs after bifurcation. The photographs show that, in many cases, the shape of branch cracks on one side of a specimen is apparently different fom that on the other side of the specimen. The fact indicates that the rapid crack bifurcation in PMMA is of three-dimensinal phenomenon. Also shown is that two branched cracks have different crack opening displacements. It means that the bifurcation of the cracks are asymmetric just after bifurcation.

This paper presents the multi-frame image-capturing system based on a few simultaneously operating high-speed photography subsystems, capable of acquiring plasma images in different parts of radiation spectra, i.e. in a visible as well as soft X-ray spectral range. The passive optical diagnostic subsystem allows recording frame sequence and streak images of plasma in visible spectrum. It consists of the streak camera and the high-speed four-frame camera. The high-speed four-frame camera is based on of the first generation image intensifiers and is able to acquire images of plasma originating in plasma-focus phenomena with minimal estimated optical gate time of about 1 ns. The two cameras based on an open microchannel plate devices allow recording four-frame plasma images in a soft X-ray range with estimated X-ray gate time of about 2 ns. All presented high-speed photography subsystems are equipped with digital readout. Some examples of the results obtained by means of the multi-frame image-capturing system, are given in the final part of the paper.

To observe and analyze detailed processes of the vortex-flame interaction in the two-dimensional coherent structure, a premixed flame is generated by a spark ignition either at the center of an organized eddy or at the midpoint between two adjacent eddies, and the initial propagation stage of the spark-ignited flame is optically observed using the simultaneous and two-directional high speed schlieren photography. The tangential velocity of organized eddy and the equivalence ratio of the shear flow are varied as two main parameters. The results obtained and analyzed show that there exists another type of vortex-flame interaction in addition to the vortex bursting, and that it is due to the eddying motion peculiar to the coherent structure in the plane shear flow. The vortex-flame interaction is named here the vortex boosting. It is concluded therefore that in the ordinary turbulent premixed flames these two fundamental vortex-flame interactions get tangled with each other in complicated manners to augment the propagation velocity. An empirical expression which takes into account of effects of both vortex and chemical properties is finally proposed.

The knowledge of the penetration, the spreading, and the atomization of a Diesel injection jet is important to improve the combustion in a Diesel combustion chamber. There are some results from investigations of the mechanism of the breakup of stationary fluid jets. But the question is, whether those results are valid for instationary jets i.e. Diesel injection jets. For this reason many tests on injection jets are carried out in order to improve the knowledge of the Diesel injection. For these studies a rotating mirror camera with frequencies up to 1.000.000 f/s and an exposure time of 15 ns was utilized. To investigate a single injection an electronic test control was used. With this arrangement it is possible to investigate this event from the start up to the end. The optical system was optimized. The jet was injected in a test chamber. In those studies the penetration velocity, the velocity and the path of single droplets, the spreading and the atomization of a Diesel injection jet were investigated. Besides the structure of the jet as function of time was interesting. The interpretation of the frames was performed by a digital image analysis system. These investigations give new insights in the Diesel injection jet.

Laser induced human serum Raman spectra of liver cancer are measured. The spectra differences in serum from normal people and liver cancerous people are analyzed. There is obvious difference between the spectrum of liver cancer and that of normal people. For the typical spectrum of normal serum there are three sharp Raman peaks (A at approximately 1010 cm^-1, at approximately 1160 cm^-1, C at approximately 1525 cm^-1) and relative intensity of Raman peak excited by 514.5 nm is higher than that excited by 488.0 nm. However, for the Raman spectrum of liver cancerous serum there are no peaks or very weak Raman peaks at the same positions of spectrum and intensity of Raman peak excited by 514.5 nm is lower than that excited by 488.0 nm. Results of more than two hundred case measurements show that clinical diagnostic accuracy is 92.86%. And then, the liver fibrosis is studied applying the technology of LIF. The experiment indicates that there is notable fluorescence difference between the abnormal and normal liver tissue, there is blue shift abnormal tissue in compare with normal liver tissue. These results have important reference values to explore the method of laser spectrum diagnosis.

To introduce shock wave as a new treatment modality for the lesions in the vicinity of brain and skull, pressure-dependent brain damages after exposure of shock wave were investigated. A novel compact Ho:YAG laser-induced cavitational shock wave generator (diameter: 15 mm, weight: 20g) was used intstead of clinical lithotriptors due to their wide distribution of shock waves. In the first part, we have developed and investigated characteristics of present generator by means of high-speed photography, shadowgraphy, and pressure measurement. Generation of localized shock wave without harmful effect of laser was observed after irradiation of Ho:YAG laser in the brass tube with internal water supply. Mechanical effect of accompanying laser-induced liquid jet was mitigated after placement of latex diaphragm with acrylic water reservoir. Maximum overpressure of generated shock wave was 15 MPa before placement of diaphragm, and 5 MPa after placement of diaphragm. In the second part, shock wave-induced brain damages were investigated in 5 male Sprague-Dawley rats. While subarachnoid hemorrhage could be observed between 1 and 5 MPa, intracerebral hemorrhage, and laceration of tissue were also observed above 5 MPa. We therefore conclude that overpressure of exposing shock wave over brain surface should be managed under 1 MPa.

The constructions and major characteristics of recent stroboscopic x-ray generators and their applications to high-speed radiographies including biomedical applications are described. The generators are as follows: (a) a 100 kV generator having a fixed-anode radiation tube, (b) a 120 kV medical generator with a rotating-anode tube, and (c) a 300 keV generator utilizing a fixed-anode tube. The type (a) and (b) generators employ large-capacity condensers of about 500 nF, and the electric charges in the condensers are discharged repetitively to each tube by controlling the grid voltage. The x-ray duration can be controlled from 0.01 to 1.0 ms, and the intensity increases with increases in the charging voltage, the duration, and the filament voltage. When the external triggering system is employed, the maximum repetition rate has a value of 50 kHz. Next, the type (c) generator has a high-voltage transformer and produces short x-ray pulses with widths of about 300 ns, and the maximum rate is about 1 kHz. The high-speed radiography was performed using a film-less computed radiography (CR) system, and stop-motion images of objects were obtained.

New generation of streak tubes intended for single-shot and synchroscan operations with femtosecond time resolution was computer modelled, designed, manufactured, tested and adopted for further application in laser research. The developed PV-FS type tubes provide close to 100 fs-time resolution in single-shot streak mode. It is important to note that the PV-FS tubes may be equipped with Peltier cooled S1-photocathodes and their spectral sensitivity may cover the range of 115 - 1550 nm. The developed photocathodes have very low surface resistance (tens of Ohm per square unit). New tubes offer a high (more than 50 line pairs/mm) spatial resolution when recording ultrafast optical images with femtosecond time resolution. Due to keeping the PV-FS external geometry similar to the well-known PV-type tubes it becomes possible to install new devices into available streak cameras (AGAT, Imacon 500, etc.).

The investigations of residual gas influence on EBI in streak tubes were continued. Model of the microdischarges in streak tubes, grounded on the theory of reciprocal ion emission is considered and it was shown, it is agree with experimental data on EBI fluctuations. The secondary electron emission from a material of an anode diaphragm was detected and investigated.

On the basis of the recently developed PV-FS-type femtosecond streak tubes supplied with the original photocathode-accelerating mesh assembly (dedicated for pulse operation) and ultra-sensitive high frequency deflection system, the experimental prototypes of a 200 fs streak camera was designed, manufactured and tested. The camera experimental time resolution > 200 femtosecond, its maximum spatial resolution along the slit direction is better than 30 line pairs/mm in dynamic mode. The range of the streak duration along the 25 mm output screen is from 50 ps to 5 ns, which corresponds to the streak speeds of 5 × 10¹⁰ - 5 × 10⁸ cm/s. The camera triggering delay is 50 ns with ± 20 ps jitter at triggering signal of 5 Volts/50Ohm/1ns rise time with the maximum repetition rate of 100 Hz. At the maximum time resolution the dynamic range is about 10. The spectral range of the recorded optical events may cover 115 - 1550 nm. The typical optical radiation intensity at 800 nm needed to illuminate the input photocathode in order to get maximum time resolution is 500 Watts/cm².

The problem of ideal first-order temporal focusing of photoelectron bunches with quasi-stationary electromagnetic fields is discussed on the basis of theoretical electron optics and computer modelling.

The Photochron 5 Streak Tube was designed at St Andrews University by Professor W Sibbett & et al. In its original form, the tube had four times magnification and was calculated to have a temporal response of circa 250 fs. Prototypes made by Photek were tested and showed temporal resolution of 400 fs. The electron optical design of the tube has been recalculated, which enables the tube to be operated at magnification as low as 2, to take advantage of advances in CCD design and photon counting/centroiding technology. We also studied the theoretical possibility of operating the tube with a small slot and no mesh. This would enable a gain in quantum efficiency inversely proportional to mesh transmission -- i.e. a factor about 1.5 times improvement. The focus is intensely anisotropic, with magnification x 2.6 in the spatial axis and 1.3 in the temporal axis. The working area of the tube is considerably reduced, to less than 100 microns width. A second iteration of the anisotropic design has been built and tested. Magnification in the spatial direction is x 2 and x 1 in the temporal direction. Working area is approximately 1.5 mm x 12 mm. The low magnification in the temporal direction can be used to increase the working area of the tube, so increasing light throughput and dynamic range, without effecting time resolution. Alternatively, time resolution can possibly be improved, providing that the readout spatial resolution can take advantage of this factor.

Different temporal instabilities, which degrade the temporal resolution of s a synchroscan streak camera, have been studied. Each of the 3 main components: the laser, the trigger and the streak camera, have their intrinsic instability, thus a degradation of the final temporal resolution is occurred. An internal PLL in the streak camera has been developed in order to improve the temporal resolution. The synchroscan signal is used to lock the phase of the deflection voltage with the laser beam as close as possible. The phase detector has 0 to 360° area detection and a jitter lower than 300 fs FWHM integrated from 10 to 600 kHz, allowing sub picoseconds synchronization with the laser beam. The slow drifts, from 0 to 25 Hz, of the phase comparator are cancelled with a laser reference directly inserted in the camera input. By the way of an image processing, the phase command voltage is modified to lock the position of this laser reference. Results show that this stabilized camera can be used immediately after it is turned on (suppression of the warm-up time) and has very good temporal resolution, even with a long time exposure (2.4 ps FWHM with a time exposure of 2 hours has been realized). This allows more exploration in detection of very weak signals.

We have developed a compact fieldable optically-deflected streak camera first reported in the 20th HSPP Congress. Using a triggerable galvanometer that scans the optical signal, the imaging and streaking function is an all-optical process without incurring any photon-electron-photon conversion or photoelectronic deflection. As such, the achievable imaging quality is limited mainly only by optical design, rather than by multiple conversions of signal carrier and high voltage electron-optics effect. All core elements of the camera are packaged into a 12" x 24" footprint box, a size similr to that of a conventional electronic streak camera. At LLNL's Site-300 Test Site, we have conducted a Fabry-Perot interferometer measurement of fast object velocity using this all-optical camera side-by-side with an intensified electronic streak camera. These two cameras are configured as two independent instruments for recording synchronously each branch of the 50/50 splits from one incoming signal. Given the same signal characteristics, the test result has undisputedly demonstrated superior imaging performance for the all-optical streak camera. It produces higher signal sensitivity, wider linear dynamic range, better spatial contrast, finder temporal resolution, and larger data capacity as compared with that of the electronic unit. The camera had also demonstrated its structural robustness and functional consistence to be well compatible with field environment. This paper presents the camera design and the test results in both pictorial records and post-process graphic summaries.

Model S-150 ultra-high speed framing camera with continuous access, characterized by a three faced, high velocity motor driven rotating mirror of aluminum substratum with a reflective overcoat made direct coating or transposition coating, a coaxial speed increaser with ratio of 2 x 13:1, a pre-magnetic-field fast open shutter with opening speed of 0.7 mm/μs, and a computer-electronic camera control with virtual buttons substituted for tens of real buttons and real monitoring of whole photographic process, has successfully been made. Specifications of the camera are as follows: the maximum economical photographic rate of 1.4 x 10⁶ pps and the maximum rate of 2.24 x 10⁶ pps corresponding to a rotating mirror velocity of 4 x 10⁵ rpm and its peripheral velocity of 800 mps, the dynamic visual resolution of 34 lp/mm along the temporal direction, the frame format of 14 mm x 20 mm. Tests and experiments verify that it is very useful and available with high quality pictures taken from the transient events with random triggering time and very strong anti-interference property.

For studying microbubbles in a medical ultrasound field (ultrasound frequency between 0.5 and 5 MHz) ultra high-speed imaging camera is required. The ultrasound typically lasts 3 - 20 cycles during which the response of the microbubbles can be highly non-linear. The frame rate of such a high-speed camera therefore should exceed 10 million frames per second (Mfps). The number of frames should be sufficient to record the whole process, therefore, more than 100 frames are desirable. In this manuscript we describe a digital ultra high-speed camera system which combines the superior flexibility and sensitivity of CCD detectors with the high number of frames available in rotating mirror cameras. In a standard run the "BRANDARIS 128" camera records a full sequence of 128 digital images at a frame rate of 25 Mfps.

Comprehensive studies upon the structure and physical properties of Ag-O-Cs photocathode with the AES and XPES techniques are presented. The photoelectron emission spectrum has been measured in situ on each stage of the photocathode preparation. Similar investigations have been carried out as to nanoparticles of Ag with size several tens of nanometers. Being activated with Cs and O, those particles are located on the thin sapphire film surface. It may be concluded that the photoemission from the Ag-O-Cs photocathodes has the same nature as the photoemission from the nanoparticles of Ag on sapphire, namely it is conditioned by the excitation of surface plasmons with concurrent emission of electrons. It also means that the nanoparticles of Ag activated with Cs and O and investigated in this paper may be conceived as a 2-dimensional photocathode. The external photoemission from Ag-O-Cs photocathodes is of strongly pronouned surface nature, with no process of transportation of electrons towards the surface. In this case the characteristic time during which a light wave is able of exciting plasmons at the nanoparticles of Ag is less than 1 fs, which makes the Ag-O-Cs photocathode most perspective from the viewpoint of getting limiting subfemtosecond-range time resolution.

Advances in understanding laser-matter interaction physical processes require extending instrumentation observations limits. In the case of high-speed photography by means of streak analyzers, the main contribution in improving instruments comes from high-speed HV electronics and new tube architectures. However, the cost of these technologies is still a limiting factor. The alternative to instrumentation renewal is based on using conventional technology (Centrally symmetric electron lens streak tube) associated to a convenient image processing. This option, relying on prior metrological characterization of the degradations generated by streak cameras, can be performed thanks to the affordable powerful computing capabilities and the widespread use of CCD readout. This paper describes a simple method for measuring static Point Spread Function (PSF) on streak tube. Experimental results are discussed and then introduced for image restoration purpose. A discussion of a deconvolution method based on Singular Value Decomposition (SVD) for a shift variant blur is briefly sketched. Application of this method shows an actual increase of streak images spatiotemporal resolution.

In order to improve the image quality of flash X-ray images, a single step process "Computed Radiography" has been tested and evaluated. In this process, which has previously been used for medical imaging, the image intensifier screen is directly scanned by a laser beam into digital format, making the image directly accessible for computer evaluation. Results of the evaluation and descriptions on how the technique can be adapted for flash X-ray imaging are presented. The computed radiography technique has been tested in high speed and extreme dynamic applications with 150 kV and 450 kV Scandiflash flash X-ray tubes. Tests have been performed both for shadow and penetration imaging. The image plates showed to have higher dynamics, smaller grain size and being less sensitive to stray light and mechanical stress than common photographic film-screen system, resulting in an increase in resolution and decrease in noise.

The CEA is developing a high energetic laser Facility for large scale investigations on plasma physics. This facility named Laser Megajoule (LMJ) will offer 240 laser beams and 1.8 MJ pulse energy is 3 ns. These laser beams will impact a target at the center of a large spherical chamber, for experiments by means of fusion by inertial confinement. We describe here a prototype of insertable Streak camera for hard X-ray experiments specifically designed to operate in vacuum (< 5 10^-6 mbar) near the target chamber. The Streak tube is based on an open and modular structure of cylindrical electrodes with a large photocathode (approximately 20 mm). Time window ranges from 1 ns up to 25 ns with triggering jitter less than 10 ps rms. The readout is made by a specific high dynamic cooled CCD camera. Cooling system (Peltier stage combined with water flow) allows a -10°C stabilized temperature on chip. The CCD camera is an ATMEL product comprising a (2048 x 2048) matrix of 14 μm square pixels. Digitizing is performed by a 16 bits conversion chain with 6 electrons readout noise. First results obtain on the Streak tube electronics and CCD camera are presented (MTF, CCD, S/N, flat field, temporal jitter and linearity or temporal resolution...). Time bandwidth estimated for this camera for the 1 ns base time will be of 45 GHz at -3 dB.

The flintlock gun represented a significant advance in early small arms development. It was the preferred method of ignition for muzzle loading military and sporting arms until eventually it was ousted, firstly by the introduction of percussion arms and then by the cartridge breech loading guns. However, it is still used by many people in target and sport shooting. This paper describes some experiments using high speed photography, intended to find a means of analyzing part of the performance of the flintlock mechanism.

Dynamical deformation and collapse process and stress wave mechanism of aluminum honeycombs subjected to the in-plane impact of a rigid impactor were investigated experimentally. Deformation process was visualized using a high-speed video camera and reaction forces were measured using force-gauges at the contact surface between the honeycomb and fixed wall. Also, numerical simulation was made using a shock code. AUTODYN-2D. Since an aluminum honey-comb has an anisotropic nature owing to its cell shape and cell arrangement, the direction of impact greatly affects the deformation characteristics. The present results were compared with our previous results for different impact direction.

The development of high frame rate imaging high energy X-rays detector system is discussed. The purpose of this paper is to highlight some of the issues involved in the development of high performance position sensitive X- and gamma-ray cameras for high frame rate imaging. New CZT technology has provided some prototypes offering more than 50% stopping power (and millimetric spatial resolution) for 5 MeV X-ray pulses. Some different CdTe and CdZnTe sensors were tested with MeV energy photons produced by the accelerators ELSA and ARCO (CEA Bruyeres-le-Chatel). The first experimental results obtained at CEA with 20 ps long are very encouraging for high energy high frame rate imaging applications.

The German Aerospace Centre carries out since many years studies on the flow and combustion of liquid jets expanding in a high pressure chamber through a single injector. For this study, liquid nitrogen has been injected into a pressurized test chamber filled with gaseous nitrogen at different test conditions. The behavior of the flow is well known on principal but the liquid zone, near the injector, is not accessible for the analysis using classical optical diagnostics. In order to be able to study this zone of the cryogenic jet, a new compact and pulsed (50 ns FHWM typical) X-ray source has been developed and utilized. During experiments carried out on the test bench M51 of the DLR, this soft X-ray flash energy, enable us to carry out radiography of the zone close to the injector (z/d < 10) for chamber pressures from 1.0 to 6.0 MPa and temperatures of the liquid nitrogen jet ranging from 100 to 130 K. The data and their Processing result in the possibility to obtain the various density profiles corresponding to injection conditions. The obtained results are compared with those collected by other methods (experimental and numerical) already used in the DLR.

In this study, we have made a low photon energy flash x-ray generator with a titanium target and have measured the radiographic characteristics. The flash x-ray generator consists of a high-voltage power supply, a high-voltage condenser, a turbo molecular pump and a flash x-ray tube. The condenser is charged up to about 30 kV, and the electric charges in the condenser are discharged to the tube after triggering the cathode. The linear plasma x-ray source forms from the target evaporation, and then the flash x-rays are generated from the plasma in the axial direction. K-series emission of titanium has been confirmed in experiments qualitatively and characteristics of the generator have been measured. K-series x-ray of titanium had a high resolution and enable us to take radiographs of a thin rabbit's ear clearly using the CR (Computed Radiography) system. The effect of titanium on the target of the soft flash x-ray tube has been indicated accordingly.

Electronic imaging has been undertaken upon a selection of AWE's high power x-ray pulse accelerators used for radiation effects testing on electronic components and small sub-systems. Principally an experimental configuration, based upon a pinhole scintillator combination, has been implemented to test the feasibility of recording by an electronic imaging system for high energy (3MeV) and high dose (>16krads) x-ray pulse sources. Recording by CCD based imaging technology has been used to image and verify the uniformity of the bremsstrahlung source. The accelerators of interest are the Short Pulse Experimental Electron Device (SPEED), which is a 1 MeV, very short (15 ns) pulse, high dose, bremsstrahlung source and the accelerator EROS (Energetic Radiation Of Samples), which is a 3 MeV, 40 krad, 85 ns pulse source. Quantification of Scintillator and camera parameters are highlighted in the paper and the unique electronic images, of the respective sources, are presented. Some future temporal imaging concepts with resolution approaching one nanosecond are also highlighted. The fundamental principles of the imaging system can be applied to other pulsed x-ray scenarios.

A method has been developed for visualizing the internal deformation fields in opaque materials during impact events using a combination of flash X-rays and digital speckle analysis. The random speckle pattern required for the digital speckle analysis is achieved by seeding the specimen with a layer of 20% coverage X-ray opaque powder, such as lead. By utilizing flash X-rays a comparison can be made of the images of the random pattern before and during an impact event using speckle pattern analysis software. This allows the displacement field to be determined.

A compact single focus x-rays flash device is described in this paper. This device is composed of the following essential components: a 50 kV high voltage power supply, a capacitor bank, a pulse forming line, a high frequency and high voltage switch, a voltage multiplier and an x-ray tube. Before breakdown into the x-ray tube, voltage is rise up to 400 kV. Leading to photon energy at a maximum of 400 keV. The duration of voltage pulses is 100 ns. The device could work in two different modes, in the continuous pulsed mode up to 500 Hz and in burst mode, each burst is composed by 3 to 5 shots. At this time the burst mode is running at 3.5 kHz frequency.

In the plasma flash x-ray generator, high-voltage main condenser of about 200 nF is charged up to 50 kV by a power supply, and electric charges in the condenser are discharged to an x-ray tube after triggering the cathode electrode. The flash x-rays are then produced. The x-ray tube is of a demountable triode that is connected to a turbo molecular pump with a pressure of approximately 1 mPa. As electron flows from the cathode electrode are roughly converged to a rod iron target of 3.0 mm in diameter by electric field in the x-ray tube, the weakly ionized linear plasma, which consists of iron ions and electrons, forms by target evaporating. At a charging voltage of 50 kV, the maximum tube voltage was almost equal to the charging voltage of the main condenser, and the peak current was about 20 kA. When the charging voltage was increased, the linear plasma formed, and the K-series characteristic x-ray intensities increased. The x-ray pulse widths were about 800 ns, and the time-integrated x-ray intensity had a value of about 10 μC/kg at 1.0 m from x-ray source with a charging voltage of 50 kV. The plasma x-rays were diffused after passing through two lead slits.

Multi-pulse imaging systems have been developed for recording images from pulsed X-ray and proton radiographic sources. The number of successive images for x-ray radiography is limited to four being generated by 25 ns, pulsed sources in a close positioned geometry. The number of proton images are provided by the number of proton bursts (approximately 60 ns) delivered to the radiographic system. In both cases the radiation to light converter is a thin LSO crystal. The radiographic image formed is relayed by a direct, coherent bundle or lens coupling to a variety of electronic shuttered, cooled CCD cameras. The X-ray system is optimized for detecting bremmstrahlung, reflection geometry generated X-rays with end point energies below 300 keV. This has resulted in less than 200 μm thick LSO converters which are 25 x 25 mm². The converter is attached to a UV transmitting fiberoptic which in turn is directly coupled to a coherent bundle. The image is relayed to a 25 mm microchannel plate image intensifier attached to a 4 image framing camera. The framing camera image is recorded by a 1600 x 1600 pixel, cooled CCD camera. The current proton radiography imaging system for dynamic experiments is based on a system of seven individual high-resolution CCD cameras, each with its own optical relay and fast shuttering. The image of the radiographed object is formed on a 1.7 mm thick tiles of LSO scintillator. The rapid shuttering for each of the CCD's is accomplished via proximity-focussed planar diodes (PPD), which require application of 300-to-500 ns long, 12 kV pulses to the PPD from a dedicated HV pulser. The diodes are fiber-optically coupled to the front face of the CCD chips. For each time-frame a separate CCD assembly is required. The detection quantum efficiency (DQE) of the system is about 0.4. This is due to the lens coupling inefficiency, the necessary demagnification (typically between 5:1 and 3:1) in the system optics, and the planar-diode photo-cathode quantum efficiency (QE) (of approximately 15%). More recently, we have incorporated a series of 4 or 9 image framing cameras to provide an increased number of images. These have been coupled to cooled CCD cameras as readouts. A detailed description of the x-ray and proton radiographic imaging systems are discussed as well as observed limitations in performance. A number of improvements are also being developed which will be described.

In this paper we give a brief report on the development of simple direct- and indirect-detection imagers for proton radiography experiments. We outline a conceptual design for a novel, multi-frame 5 mega frames per second (Mfs) hybrid imager. The high-density interconnect is identified as a critical enabling technology. We present a description of a 3D electronics packaging cube, which was completed in a recent feasibility study.

The FXR is an induction linear accelerator used for high-speed radiography at the Lawrence Livermore National Laboratory's Experimental Test Site. It was designed specifically for the radiography of very thick explosive objects. Since its completion in 1982, it has been very actively used for a large variety of explosives tests, and has been periodically upgraded to achieve higher performance. Upgrades have addressed machine reliability, radiographic sensitivity and resolution, two-frame imaging by double pulsing -- improvements that are described in detail in the paper. At the same time, the facility in which it was installed has also been extensively upgraded, first by adding space for optical and interferometric diagnostics, and more recently by adding a containment chamber to prevent the environmental dispersal of hazardous and radioactive materials. The containment addition also further expands space for new non-radiographic diagnostics. The new Contained Firing Facility is still in the process of activation. At the same time, FXR is continuing to undergo modifications aimed primarily at further increasing radiographic resolution and sensitivity, and at improving double-pulsed performance.

The fundamental study on a high-intensity flash light generator and its applications are described. This generator is composed of a high-voltage power supply, high-voltage main condensers of 8 and 4 μF, a thyristor pulse generator as a trigger device, and a high-intensity xenon tube. The main condenser is charged up to 2.5 kV by the high-voltage power supply, and the electric charges in the condenser are discharged to the xenon tube by the thyristor pulse generator. The flashlights are then produced. The tube voltage and discharge current displayed almost the dumped oscillations. The maximum voltage was equal to the initial charging voltage, and the maximum current increased according to increases in the charging voltage and the capacity. The current was 4.1 kA with a charging voltage of 2.5 kV and a capacity of 8 μF. The pulse widths of flashlights were almost constant at a constant condenser capacity and increased with increases in the capacity. The widths were about 8 μs with a capacity of 8 μF. The shadowgraphy was performed using this generator and a trigger delay device. Finally, we performed tentative studies on parallel and point light sources.

Aiming to realization of compact flash x-ray facilities, flash x-ray generator with two-stage Marx generator and a krytron pulse generator was constructed and its characteristics were verified in present study. Target and cathode of the x-ray tube was tungsten rod and graphite disk plate, respectively. Two-stage Marx generator applied high voltage to the target and discharge between electrodes produced plasma and x-ray. Experiments revealed the relationship between tube voltage, tube current and applied voltage to x-ray tube. Effect of distance from target to cathode was also made clear. Measurement of radiation output with plastic scintillator indicated the shorter pulse duration than 100 ns and the effect on application of present experimental configuration to high-speed photography. Radiographs were taken with computed radiography (CR) system. The photographs displayed enough resolution to perform fine photography and existence of soft x-ray for wide purposes. Present study implies application of present simple x-ray system to realization of compact and general-purpose x-ray generator.

Quasi-monochromatic parallel flash radiography system utilizing a plane-focus plasma x-ray tube in conjunction with an x-ray lens is described. The x-ray generator employs a high-voltage power supply, a low-impedance coaxial transmission line, a high-voltage condenser with a capacity of about 200 nF, a turbo-molecular pump, a krytron pulse generator as a trigger device, and a flash x-ray tube. The high-voltage main condenser is charged up to 50 kV by the power supply, and the electric charges in the condenser are discharged to the tube after triggering the cathode electrode. The flash x-rays are then produced. The x-ray tube is of a demountable triode that is connected to the turbo molecular pump with a pressure of approximately 1 mPa. As the electron flows from the cathode electrode are roughly converged to the target plane by the electric field in the tube, the weakly ionized plasma x-ray source, which consists of copper ions and electrons, forms by the target evaporating. Both the tube voltage and current displayed damped oscillations, and their peak values increased according to increases in the charging voltage. In the present work, the peak tube voltage was almost equal to the initial charging voltage of the main condenser, and the peak current was about 20 kA with a charging voltage of 50 kV. The dimension of x-ray source was almost equal to the target diameter of about 10 mm, and the x-ray pulse widths were less than 1 μs. When the charging voltage was increased, the plasma x-ray source formed, and the characteristic x-ray intensities of K-series lines substantially increased. The quasi-monochromatic x-rays from the plane-focus tube were formed into parallel beam by a polycapillary plate with a hole diameter and a thickness of 25 μm and 1.0 mm, respectively, and quasi-monochromatic radiography was performed by a film-less computed radiography system.

The AIRIX induction accelerator used for flash X-ray radiography is operational for two years, at CEA-Moronvilliers near REIMS (France). This single shot machine is composed by: (1) an injector that delivers a 3.6 - 4 MeV/2-3 kA/60 ns electron beam. (2) an accelerator composed by 16 blocks of 4 induction cells, that accelerate and transport the electron beam until 20 MeV. (3) 32 High Voltage generators that powered the induction cells: 250 kV per cell. (4) a drift and focalizing section, that transport the beam from the accelerator to the final Tantalum target. The acceptance test of this installation has been made in 2000. For that step we have choosen to work with a 2 kA electron beam. All the criteria for AIRIX qualification for hydrotest experiment have been reached with this current. We present in this paper the different measurements we made to characterize the electron beam from the injector until the end of the accelerator and the adequation with the results and the beam transport calculation. The beam image is realized with a fast gated camera that observes the Optical Transition Radiation(OTR) (produced when a charged particle passes from the vacuum to the material of a metallic foil) or Cerenkov Radiation (CR). To insure the AIRIX peformances in the time and to improve them, we have begun some specific studies. In parallel to simulation codes for beam transport, we develop optical diagnostics. The idea is to explore the intrinsic characteristics of OTR to measure the electron beam profile and electron beam divergence in a single and same shot. That will also permit the measurement of the emittance of the beam. Those measurement will able to be time resolved if we associate a streak camera. For specific hydrotest experiment we will need to have more useful X-ray dose. To increase this parameter, we have begun some studies with a 3 kA electron beam. We show in this paper the electron beam characterization made at this current and the comparison with calculations. The other part that was included in the AIRIX project concerns the X-ray imaging. For that, we have developed a system, called the gamma camera, baed on segmented scintillator associated to an MCP amplificator and a film readout. We present in this paper a first improvement of the film readout of this system.

The dynamics of femtosecond laser ablation from wide bandgap insulators (Al₂O₃, BaF₂ and CaF₂) at intensities below the single shot damage threshold (10¹¹ - 10¹³ W/cm²) is characterized by efficient surface ionization, followed by the explosive emission of positive ions and small clusters, with a kinetic energy of about 100 eV (Coulomb explosion). The multiphoton coupling of the laser to the transparent material is strongly promoted by defect resonances within the bandgap, eventually generated during a considerable number of incubating pulses before a steady ablation regime is reached. At the bottom of the ablation crater, produced by an accumulation of several thousand laser pulses, periodic surface structures are developed, with a typical scaling in the nanometer range. Occasionally, these structures exhibit features like bifurcations or columns growing out of plane. The feature size and shape appears to be more sensitive to the applied laser intensity resp. irradiation dose than to wavelength or angle of incidence. The ripples cannot be explained as a result of an inhomogeneous energy input, e.g. due to interference. Instead, we suggest that the ripples are a consequence of the surface relaxation via self-organization.

A new concept of pulse laser ablation target were proposed. The idea is two-fold; that is, the target material to be ablated is a very thin layer deposited on a surface of some substrate material. As the substrate material, we will choose a transparent material like polymer or glass. Through the transparent material, a pulse laser beam is focused onto the thin film layer from rear side. In this way, we have tried to produce high energy particle beam without slow particles and droplets. Behavior of plume induced by the ablation of thin carbon film of 200 nm deposited on a polymethylmethacrylate (PMMA) substrate has been examined. Thin film target is found to achieve high energy density states by absorbing the pulse laser energy. An Nd:YAG laser of infrared wavelength is used in this study due to the efficient absorption of energy by the ablated plasma plume. Ablation emission was observed by the high-speed streak camera. Plume is shown to be induced at the carbon fllm surface and also at the opposite PMMA surface. Several velocity groups are recognized in the plume. Stress waves in PMMA plate placed close to the thin film target was observed by the pulse laser shadowgraphy.

The change of the matrix structure of glass is investigated during and after irradiation with ultrashort pulsed laser radiation (100 fs < t_p; < 3 ps) at the wavelength λ = 810 nm. The dynamics of the plasma expansion and the stress formations are visualized by time-resolved Normarski-photography. Optical microscopy visualizes the structural changes in glass. The spatial stress distribution and the refractive index change are shown in the time range 100 fs < t < 120 ns. The ionization state of atoms and/or the formation of color centers has been investigated by transient absorption spectroscopy (TAS) in the time regime 100 fs < t < 120 ns. The temporal change of the spectra shows different regimes, which can be explained by the electron and phonon relaxation.

Laser treatments of various metals are studying depending on the laser wavelength, pulse time duration and shape, and fluence (laser/metal interaction regime). Low fluence excimer UV laser melting process of gold layer is shown to improve the corrosion resistance of multilayer (Au/Ni/Cu alloy) electrical contacts. For this application the homogenity of the laser beam as well as the initial Cu substrate roughness are found to be limiting parameters of the process. Carburization of Al alloy, performed in C₃H₆ atmosphere with a KrF laser induces the incorporation of carbon atoms over about 4 μm depth. The crystalline Al₄C₃ synthesized at the surface leads to a strengthening of the light Al alloy, which is of great interest for application in car industry. The study shows that diffusion of C atom in the target is possible because of a plasma presence on the surface which supports the molten bath life time and induces dissociation of the ambient gas. In the last example of laser metal surface treatment presented in that paper, a commonly used steel is treated in air with different lasers at a fluence above the plasma formation threshold. It is seen that the machining oils covering the surface before the treatment can be efficiently removed and that new compounds (nitride, carbide and oxides) are formed at the surface.

The theoretical and computational studies based on the novel physical and mathematical model of nonequilibrium chemical processes involving vibrationally and electronically exited molecules have shown that selective excitation of reacting species by laser radiation results in a considerable reduction of self-ignition temperature, decrease of induction and combustion times, and initiates detonation in supersonic flow at relatively low radiation energy inputted into the mixture. These effects are due to production of the novel channels of high reactive radicals formation and enhancement of chain mechanism of combustion and are not associated with the thermal action of absorbed radiation.

Explosives can easily generate the high energy and the ultra-high pressure. The performance of explosive depends on its own chemical poperty, the detonation wave usually propagates with the stable value of pressure behind it, the pressure is so called "Chapman-Jouguet (C-J) pressure." If the higher pressure over C-J pressure can be expected to occur, it is very effective for a development of new materials. We take notice of Overdriven Detonation (following O.D.D.) phenomenon that expects to bring out higher detonation pressures than C-J pressure of explosive. This phenomenon can be occurred when the flyer plate of high velocity impacts the explosive, or the explosive compressed by the advance detonates, or converging detonation of the explosive.

The paper reports an experimental study of production and propagation of diverging and converging spherical shock waves. In order to quantitatively observe spherical shock waves and the flow field behind them, an aspheric spherical transparent test section was designed and constructed. This 150 mm inner-diameter aspheric lens shaped test section permits the collimated visualization laser light beam to traverse the test section parallel and emerge parallel. Spherical diverging shock waves were produced at the center of the spherical test section. In order to generate shock waves, irradiation of a pulsed Nd:YAG laser beam on micro silver azide pellets were used. The weight of silver azide pellets ranged from 1 to 10 mg, with their corresponding energy of 2.1 to 21 J. Pressure histories at different points over the test section were measured to validate production of uniform shock waves. After reflection of spherical shock wave from the test section, a converging spherical shock wave was produced. Double exposure holographic interferometry and time resolved high speed photography were used for flow visualization. The whole sequence of diverging and converging spherical shock waves propagation and their interaction with product gases were studied.

Maximum penetration is the goal for good shaped charge designs. To achieve this from the jet, built by the liner collapse process, the jet should have the maximum possible tip velocity for the used liner material and should be extremely straight so that the residual jet portions can arrive at the crater bottom, to achieve a low so-called cut-off velocity. For this purpose the use of the flash X-ray techniques is well known. Great deviations can be easily seen. But the angle deviations should be resolved in minutes in the two axes. For this purpose the author developed the synchro streak technique. The jet is observed in one or two or three different distances with one or two streak cameras, applying the profile streak technique in orthogonal views, so that a two dimensional analysis can be made as a function of time with very high space resolutions. Besides the wanted very accurate measurements of the jet angle deviations, also their surface structure can be observed by strong front illuminations with powerful argon flash bombs. Such synchro streak records have shown smooth jet surfaces in the tip regions, but rougher surfaces in the middle and the rear sections of the jets. The radial crater growing process as a function of time, caused by such extremely fast impactors, can be described with analytical equations. By the optical observation of the radial growth process of the jet at different penetration velocities this analytical theory was proven and confirmed. It is astonishing, that shaped charge research groups and developers are not really knowing and using the possible and relatively easily available optical diagonstic techniques, to find out the limits of the shaped charge jet performances of their designs with the manufacturing tolerances. This paper gives the optical diagnostic potentials and advanced techniques.

When the loading is highly dynamic, the prediction of dynamic structural response by means of numerical calculations needs optimized constitutive relations to describe plastic behavior of metallic materials. In order to extend the domain of strain rate and strain explored in classical characterization experimental programs, free expanding structure tests are particularly well suited to models evaluation by virtue of their inherently homogeneous stress state. The expanding shell test allows to load a material in the domain of high strain levels while strain rate is about 10⁴ s^-1. The experiment (experimental apparatus, measurements...) is described with the difficulties encountered for the interpretation of the experimental data. The radial velocity is measured with the Doppler Laser Interferometry technique (DLI) for different locations (at 0°, 30° 45° from the revolution axis) in order to record border effects. The accuracy of this technique allows the evaluation for the shock wave propagation stage in the shell (a short characteristic duration of a few μs) and the plastic deformation (duration of tens of μs). Furthermore, expansion of the material sample is observed by means of ultra high speed cameras. The film is a good tool for examination of damage appearances, detonation products problems, fracture of elements of the experimental set up. Under some assumptions, the numerical transformation of radial velocities gives indications about the evolution of the strain, stress, strain rate and temperature rise (this last parameter is related to plastic work). It is also shown the correlation between experimental, analytical and numerical approaches. This review is presented for three materials: copper, tantalum and TA6V4. It is demonstrated that sensitivity to plastic contribution to the motion of matter under high dynamic deformation states is related to strength, density and melting temperature. The contribution of this test to modeling of constitutive equations is also discussed and further works are finally proposed.

The observation of the radial and axial breakthroughs on cylindrical acceptor charges, symmetrically loaded by a shaped charge jet in the axis at one end surface, allows to measure the build up distance from the side and by the radius of the axial breakthroughs. The selected test set up for the observations in the two planes -- parallel to the acceptor charge axis and prependicular to the charge axis on the end surface and the results, achieved with this diagnostic methods, will be described.

A novel energy-resolved four-frame x-ray framing camera was developed for Qiang-guang I high power krypton gas-puff Z-pinch generator. The camera consisted of a pinhole array, two kinds of filters, a micro-channel plate (MCP) image intensifier, and a charge coupled device (CCD) camera. There are four microstrips on the input surface of the MCP. Two images are formed on each microstrip by two pinholes, one is filtered by 2 μm (micron) aluminized mylar and sensitive to 150 - 300 eV photons and those above 400 eV, another is filtered by 1 μm (micron) mylar plus 0.25 μm (micron) aluminum and sensitive to photons greater than 300 eV. Finally, the experimental results are discussed.

Hot-spot formation is regarded as the principal phenomenon by which energetic materials start to react, deflagrate and, in some cases, detonate. The principal mechanisms by which these localized regions of high-temperature form have been identified and widely studied; mechanisms such as friction, pore collapse and jetting have been highlighted. High-speed imaging techniques have been applied to beds of ammonium nitrate under high velocity impact in order to evaluate the contribution of each mechanism to the ignition of this material.

In details a test method is described which gives the delay times and buildup distances of the initiation of squeeze cast or plastic bonded high explosive charges. A special test setup arrangement is used to observe the incoming detonation wave of a high explosive train as the donor or initiating charge, then the breakthrough of the detonation wave at the acceptor charge in the axial direction and in the 90° direction. This allows to define the shift of the detonation breakthrough in the longitudinal direction, and the corner turning distance in the transverse direction and the build-up distances in both observed directions.

In our ordinary detonics experiments, the timing measurements are generally done with passive optical fiber sensors. Each sensor end is fitted with a metallic cap which contains a specially machined air chamber known as the "ionization chamber." When a projected metallic plate shocks the sensor, the air located in the ionization chamber receives a strong shock, which ionizes both the trapped air and the fiber silica core. The emitted light travels down the fiber to the slit of an electronic streak camera or an optic/electric converter coupled with a digitizer. One of our main objectives is to measure the shock breakout time very accurately. Such a measurement is practically impossible to make on a sensor of this type due to low shock pressure level and the difficulty of making contact between the sensor and the target especially in complex devices. This is why we have developed a new probe called "active fiber." This probe is located close to the surface (less than 3 mm) and is composed of two fibers; the first is used to illuminate the target with a laser source and the second collects the back-reflected light which is then analyzed with a photo-detector. It is a "no contact" measurement for shock breakout chronometry. At target impact, a light signal is produced according to the capped passive optical fiber principle. When the dynamic pressure level is low (150 kbar) we obtain a better chronometric accuracy.

For more than 30 years now, Doppler Laser Interferometry has been used in detonics to measure velocity versus time accurately. The means is composed of: a laser source, an optical fiber bringing light to the moving target, another which collects back-reflected light, a device built around a Fabry-Perot interferometer to create the rings pattern, a streak camera. In the beginning, the source was a CW singlemode argon laser with a 7 W output power. Later, it was replaced by a wide spectrum rhodamine dye laser requiring two twin Fabry-Perot interferometers, the first one modulating the spectrum and the second analyzing the Doppler shifted light; the available power was 1 kW for a 40 μs pulse. Recently, we have improved the means by increasing the channel number with sufficient output power, replacing the dye with a solid amplifier, increasing pulse width, decreasing the velocity and time uncertainties and reducing the volume and the cost of the equipment. To achieve this quality we acquired a long-pulse singlemode Yag laser. It has 15 channels, each providing 1 kW with a 70 μs rectangular pulse at 532 nm. The analysis bench uses only 1 Fabry-Perot interferometer for 5 channels. The laser, target and analysis bench are connected through a 3 optical fibers bundle; one for lighting, one to measure velocity and a third one to record the photometric curve and determine shock breakout time accurately. To improve accuracy, we worked on two areas: (1) the equipment with the anamorphic optical device, the value of the fringe constant and the number of rings lit on the camera slit, (2) the building of a chart where we write all influent parameters in order of importance: in order to decrease the uncertainty of velocities less than 1000 m/s, we need to evaluate the influence of electronic streak camera distortion.

A high-speed photographic investigation of the initiation and propagation of radial and median cracks in transparent samples of a brittle epoxy and polymethylmethacrylate is described. The cracks were generated by low-velocity impact with hard spherical and conical indenters, and it is shown that radial cracks always initiate on the impacted surface at the circle of contact. These radial cracks then grow to form median cracks, encircling the deformed zone around the indentation. High-speed photography has also been used to elucidate the fracture processes involved in making stone tools.

CMOS active pixel sensors (APS) have performances competitive with charge-coupled device (CCD) technology, and offer advantages in on-chip functionality, system power reduction, cost and miniaturization. In this paper, we present characterization of a fast CMOS APS used in an imager for high-speed laser detections, which can replace the streak cameras. It produces the intensity information in function of one spatial dimension and time [I = f(x,t)] from one frame in two spatial dimensions. The time information is obtained for the first prototype camera to delay successively the integration phase in each pixel of the same row. The different noise sources of the APS sensors such as shot noise due to the photo sensor, the thermal noise and flicker noise due to the readout transistors and the photon shot noise are presented to determine the fundamental limits on image sensor. The first prototype FAMOSI (FAst MOS Imager) is composed of 64 x 64 active pixels. The simulation and experimental results show that a conversion gain of 6.73 ± 0.25 μV/e^- has been obtained with a noise level of 87 ± 3e^- rms. The power consumption of the chip is 25 mW at 50 images/sec.

In this paper, we present implementations of a pattern recognition algorithm which uses a RBF (Radial Basis Function) neural network. Our aim is to elaborate a quite efficient system which realizes real time faces tracking and identity verification in natural video sequences. Hardware implementations have been realized on an embedded system developed by our laboratory. This system is based on a DSP (Digital Signal Processor) TMS320C6x. The optimization of implementations allow us to obtain a processing speed of 4.8 images (240 x 320 pixels) per second with a correct rate of 95% of faces tracking and identity verification.

In this paper we present a hardware design, built from scalable components named binary correlators, to exploit in real time the high-speed image grabbing in PIV (Particle Image Velocimetry). PIV can produce instantaneous measurements on a full flow field if real time processing can be reached. Thus, a specific hardware system is required. This hardware system is designed to allow the component scalability by using hardware templates which is grouped to form a binary correlator. Moreover, binary correlators are suitable as processing units and can be integrated in a specific architecture named Round-About. Real time measurement can be attained with only one FPGA.

The quality of compressed images can be remarkabley improved if the dictates of the Human Visual System (HVS) requirements are followed. To achieve this goal, our strategy is to exploit human visual masking effect using a subband decomposition. A combination of both intra channel and inter channel masking property is then performed. This scheme exploits the lowpass character of the perceptual masking for natural color images in estimating the amount of available masking. Results obtained show an improvement of the quality of reconstructed color images compared to existing compression schemes like standard JPEG2000.

Dynamic range measurements have been made on EEV P8307 Photochron II type) streak image tubes with both internal microchannel plate (MCP), and externally coupled wafer intensifier tube, image amplification. When arranged for equal radiant gain at 560 nm, both configurations showed comparable dynamic range of approximately 1100 and approximately 2900 for 30 ps and 100 ps duration (fwhm) input pulses respectively. The variation in dynamic range with photocathode current density was also measured and the results compared to a computational model based on Coulomb repulsion in the image tube. Experimental data are compared to the model and shown to be in moderate agreement.

Up to date, all of recording surface of rotating mirror framing cameras has been a cylindrical surface with a circular cross section fitted the inherent transcendental image locus, which is named the classical substitution circle theory that is not perfect and hard obtaining good results because of the principle errors. However, in this paper a new advanced designing theory of rotating mirror framing cameras, substituted for the classical theory and proven very useful and available to simultaneously get non-defocusing image recording, coaxial imaging for all relay lenses and equispeed sweeping, has been developed.

The paper is devoted to a study of methods for characterizing and diagnosing the beam quality of high energy laser. It begins with a review of the rationality and usability of the parameters that have been used for characterizing laser beam quality. Considering the specific characteristics of high energy laser, we suggest characterizing the beam quality of high energy laser with diffraction limit multiple β-factor and encircled energy ratio BQ. Then the selection of the referential (or ideal) beam for β-factor is discussed in detail and the far-field diffraction intensity distributions and divergent angles of various referential beams have been calculated and compared. The results show that among all of referential beams with the same diffraction area or external aperture size, the circular solid homogenous beam has the smallest far-field divergent angle, thus choosing such a beam as the ideal beam would be the most reasonable and strongly proposed. Finally, techniques for diagnosing the beam quality of high energy laser are presented.

To investigate the spectral specialities of digestive cancer serum for diagnosis, fluorescence and Raman spectra of normal, digestive cancer (both before and after operation), such as stomach cancer, esophagus cancer and atrophic gastritis sera were measured in the visible region in this study. Results demonstrate several points. First, all spectra except esophagus cancer were characterized by three sharp peaks (A, B and C), but we cannot differentiate them from each other at once. The intensity of each peak was different in different spectrum. Second, after samples were radiated by laser, fluorescence weakend along with red shift of its band center, and spectral changes of normal and stomach cancer (after operation) cases were different from other samples. It was also observed that spectral changes of atrophic gastritis were very similar with stomach cancer (such as the red shift of fluorescence peak is more than 12 nm) after radiated by laser, however, there are still some distinctions that can be used to differentiate them from each other. At last, a notable difference is that the relative intensity of peak C excited by 488.0 nm is higher than excited by 514.5 nm in spectrum of stomach cancer, whereas lower in other cases.

Ultra high-speed X-ray framing cameras have improved considerably in recent years. Frames with temporal resolution of less than 100 ps are achievable, due to application of the non-linear amplification properties a microchannel plate (MCP). However, in the case of frame resolution under 100 ps, the propagation delay of the shuttering pulse on the MCP poses a significant problem to the maintenance of simultaneity of gated images. In the present research, a method to augment the simultaneity of images is presented. In previous designs, the photocathode was coated onto the MCP input surface. The improved design presented here separates the photocathode from the MCP detector. The transit time of the photoelectrons is varied at each point on the gated electrode is with respect to the MCP detector. Results show that the simultaneity of images is improved with this new design.

The dynamic response of three-dimensional pariculate aggregation subjected to the impact of a spherical projectile is investigated experimentally and also numerically using discrete element method. It becomes clear the effect of the repulsion of spheres and wave propagation on the scattering behavior of particulate aggregation. It is found that the scattering behavior of the particulate aggregation depends on the lateral gap between nylon spheres.

Experimental study of diesel spray photography was executed with three dimensional pseudo high-speed photography. Diesel spray was observed and proved that it developed through three steps. At the initial stage, the leading tip of the spray began to interact with entrained gas. At the middle stage, the atomization was actively promoted by the collision between the decelerating leading tip and the overtaking succeeding part. At the final stage, the leading tips having plural horn-like projections ran in parallel.

The experimental study is conducted to estimate fracture process of the cylindrical rock specimen. In this experiment, an explosive is used as the explosion source, and a pipe filled with water is arranged between the explosive and the cylindrical rock specimen. The main purpose of this fracture test is to collect the experimental data on the behaviors of the dynamic fracture of the rock. In addition, one of the aims of this test is to estimate the dynamic tensile strength of the rock in wide range of strain rate utilizing Hopkinson's effect. Therefore, during the fracture process of the rock, the free surface velocity and the fracture part near the free surface were observed by a laser vibration meter and high speed camera. The precise detonator was used to control the initiation time of the explosive by using an accuratley controlled blasting machine. The results of the fracture test for Kimachi sandstone and the validity of this test are discussed. In order to understand the relationship above fracture condition and the incident underwater shock wave into the rock specimen, the numerical simulation is carried out. The 2D hydrodynamic code based on ALE finite difference scheme is employed. In the case of the fracture test with 50 mm water pipe, the incident underwater shock wave into the cylindrical rock specimen has irregular pressure distribution near the shock front.

Two kinds of photoinduced periodic microstructures in azodye-doped polymethylmethacrylate were fabricated by interference of two coherent beams of a nonresonant femtosecond laser. One is volume holographic gratings induced by interference of two fs-laser beams with same frequency; the other is molecular polar orientation induced by dual-frequency coherent fs-laser excitation at fundamental and second harmonic frequencies. The photoinduced holographic gratings consist of two surface relief gratings and refractive index modulated gratings in the interior of the polymers. Diffraction efficiency up to 90% of the first-order Bragg for the gratings was obtained. For the photoinduced molecular polar orientation, three kinds of noncentrosymmetries of the polymer films were optically tailored using appropriate combinations of the writing beam polarizations.

To study the main features of local melting more detail in situ investigations of mechanism of this effect were carried out at incoherent light irradiation with different pulse durations and irradiation power densities. These investigations were made using special long-focus microscope and high-speed camera. The results of in situ investigation of the density and sizes of local molten regions on the silicon surface are presented. In this work it was established that for all used light pulse durations the dependences of density of local molten regions on time has a similar character. Three stages are observed: (1) very fast increase from 0 (at the moment of local molten regions nucleation) up to the maximum value; (2) the plateau; (3) decrease due to coalescence of neighboring local molten regions. These results are provided that local molten regions are predominantly created during a relatively short time interval. It also has good agreement with the model of superheating of the semiconductor surface with respect to the equilibrium melting point during the pulse light irradiation.

This paper presents the construction details of the multi-frame optical cameras and the gating pulse generating system applied to the dynamic supplying of the first generation image intensifiers. Presented cameras are equipped with digital readout and are able to acquire multi-frame images of investigated object with minimal estimated optical gate time of about 1 ns. The special method and suitable experimental arrangement are proposed in order to determine an actual optical gate time of the gated image intensifiers. Some examples of the results obtained by means of the multi-frame optical cameras, are given in the final part of the paper.

This paper presents the construction details of the X-ray frame cameras and the gating pulse generating systems applied to the dynamic supplying of open microchannel plate-based devices. Presented cameras are equipped with digital readout and are able to acquire one-frame or four-frame images of plasma originating in plasma-focus phenomena with minimal estimated X-ray gate time of about 800 ps. Some examples of the results obtained by means of the nanosecond X-ray frame cameras, are given in the final part of the paper.

The noise and mode-locking phenomena of a hybrid soliton pulse source (HSPS) utilizing Gaussian apodized fiber Bragg grating is described. The HSPS is modeled by a time-domain solution of the coupled-mode equations including spontaneous emission noise. Relative intensity noise (RIN) is calculated using numerical solutions of these equations. It is found that with and without noise near transform limited pulse are only generated over a limited frequency range even if system is properly mode-locked over a wide frequency range around the fundamental mode-locking frequency. If transform limited pulses are not obtained at the fundamental frequency, there is no noise peak in the RIN spectrum at this frequency.

This paper considers a 9-frame photorecorder that has been developed on the basis of an IR camera of ionization type with the use of an image converter. The photorecorder operates in the spectral range of 1 - 10 μm at a frame rate of 10 - 200 kHz and frame duration of I-50 μs. It has the temperature detection threshold of 400°C and spatial resolution of > 10⁴ elem./frame. The photorecorder will find the use in recording the structure of thermal fields in fast processes (gas dynamics, ballistics, pulsed welding, and thermal treatment of surfaces).

Electronic flash lamps are being developed at the Lawrence Livermore National Laboratory (LLNL). These lamps are intended to replace the traditional explosively driven Argon-gas filled light sources (Argon candles) that are currently used to provide illumination for high speed rotating mirror-framing cameras. At Livermore, we are developing an electronic flash lamp system that can match or exceed the light output of a traditional Argon candle. These systems utilize a Plasma Arc Lamp developed by PRISM Science Inc of Woburn, MA, USA. In the past, high-speed photography requiring explosively driven light sources were a one-time-only even that destroyed fixtures and optical alignment. The electronic flash lamp system, utilizing the Plasma ArC Lamp, will replace the explosively driven lighting systems and provide the capability to dry run experimental setups and repeat tests without damage to the experimental set-up. The electronic flash lamp system eliminates the problem of collateral damage to the experiment and does not add to the overall amount of explosives needed for single test. Since the Pulsed-Power driver is remotely located, only the flash lamp itself is destroyed when the explosive shot is fired. The flexible geometry of this light source also enables the user to create complex light patterns as well as photograph very large areas with a single lighting system. This electronic flash lamp system will provide an extremely bright, stable, and repeatable light source for rotating-mirror framing cameras operating at one million frames per second, using both black & white or color films. The design of the Pulsed-Power driver and the flash lamp, along with experimental data and results will be discussed.

A transformer is described, which is build of cables or lines. It can handle ns pulses and can transform voltages or currents in multiples of one. Furthermore it is possible to construct pulse shapes.

A new kind of spectral analytical system has been developed for taking time-resolved spectrum of transient emission. In this system, a special translator converts the time-distribution spectrum into the space-distribution spectrum, and the time-dependent spectrum is recorded by a 2-D CCD device, accompanied with a MCP intensifier. The time resolution of 20 ns and the recording time of 120 ns have been achieved in the experiment for Ar emission shocked to 12000 K.

By the injecting nozzles' position of the pressurized head tank attached to the water bathtub, water jet flow can be injected to the rectangular water bathtub or diffuser shape water bathtub. The fluid velocity can be set to two kinds of speeds in these bathtubs. The purpose of present study is to visualize flow pattern inside water bathtub. The water bathtub having uniform water flow can be utilized as a very small pool in which everybody can enjoy swimming or can practice physical exercise for health. The utility values for water bathtub can be found in many fields. In this study, we use small transparent rectangular water bathtub made of acrylic resin and materials for the observation of flow pattern inside in it. The method how to make uniform flow inside water bathtub is by injecting water from many jet nozzles attached to the pressurized water tank situated in the front side of water bathtub. Then the downstream water is rejected from overflow bank attached to the rear side of water bathtub. The experiment to visualize flow inside bathtubs is carried out by using liquid and powder as tracers. Much technical knowledge is obtained by the present study.

In the current study, characteristics of the laser-induced plasma were investigated in a gas filled chamber or in a gas jet by using a relatively low intensity laser (I ≤ 5 x 10¹² W/cm²). Temporal evolutions of the produced plasma were measured using the shadow visualization and the shock wave propagation as well as the electron density profiles in the plasma channel was measured using the Mach-Zehnder interferometry. Experimental results such as the structure of the produced plasma, shock propagation speed (V_s), electron density profiles (n_e), and the electron temperature (T_e) are discussed in this study. Since the diagnostic laser pulse occurs over short time intervals compared to the hydrodynamic time scales of expanding plasma or a gas jet, all the transient motion occurring during the measurement is assumed to be essentially frozen. Therefore, temporally well-resolved quantitative measurements were possible in this study.

Experimental results on classical long spark development optically studied in July-August, 2002 at the High Voltage Research Center (HVRC), Istra, Russia have been presented. Main goal of these studies was to test universal streak and framing cameras K004M and K008 developed by the BIFO Company, Russia for the University of Florida, USA to be used at the International Center for Lightning Research and Testing (ICLRT) at Camp Blanding, Florida. Both cameras were tested at the conditions (solid angles, spatial and time resolution, sensitivity etc.) being like as much as possible to those expected in actual triggered-lightning experiments at Camp Blanding. Basic results on testing have been found to give hope well enough for the triggered-lightning research. Additionally to the testing, some features of long spark development in different stages have been studied using up to three devices operated synchronously. In combination with two cameras pointed out above, an old analog image converter streak camera of FER14-type (designed in 1980 by the VNIIOFI, Moscow as requested by the All-Union Electrotechnical Institute, Istra) instrumented with a novel CCD readout system SU04-type (designed by the BIFO Company) was being used. This combined system FER14+SU04 has been found to operate well enough too. Some experimental results with pictures presented expand available data and current knowledge on electrical discharge in large air gaps.

Different laser beam distributions such as the beam with uniform profile. Gaussian, super-Gaussian and flattened Gaussian beams is discussed. Under the same power and radius, the expressions of intensity distributions and beam fill factors (the ratio of maximum intensity to average intensity) varying with beam orders for these beams have been derived, the propagations of laser beams with different profiles through an aperture lens are analyzed and compared. In the heat conduction equation, laser beam with different spatial profiles as a surface heat source is included. Numerical calculations are performed to give the different thermal effects on a thin 30CrMnSiA metal slab induced by these beams.

The purpose of this discussion is to familiarize readers with an overview of high-speed imaging technology as a means of analyzing objects in motion that occur too fast for the eye to see or conventional photography or video to capture. This information is intended to provide a brief historical narrative from the inception of high-speed imaging in the USA and the acceptance of digital video technology to augment or replace high-speed motion picture cameras. It is not intended a definitive work on the subject. For those interested in greater detail, such as application techniques, formulae, very high-speed and ultra speed technology etc. I recommend the latest text on the subject: High Speed Photography and Photonics first published in 1997 by Focal Press in the UK and copyrighted by the Association for High Speed Photography in the United Kingdom.

In the present work the photoinduced phenomena in chalcogenide glasses thin films, that have direct relation to the optcial record, storage and its copying was considered. The main properties of selected chalcogenide photoresist films are presented. The parameters of photoresistive layers for two regimes of laser irradiation (continuous and pulse) are given. The reflective diffraction gratings with high efficiency were obtained in the result of holographic recording, subsequent chemical treatment, and metallization of the photoresist surface. A considerable increase in the light sensitivity was achieved due to the optimization of the photoresist composition, the recording and etching conditions. The possibilities of additional increase of photoresist sensitivity are discussed.

We have developed a framing tube with 80-mm photocathode for capturing two frames in less than 100-ns onto a 50-mm phosphor screen. A proven electron optics trajectory code was used to design the tube for imaging fidelity over wide dynamic range. This code's full accounting of space charge effects is essential for its ability to simulate accurately the distributed photoelectronic trajectories from the entire large photocathode area. Our approach and guideline for designing the electron optics are described. Results of trajectory simulation and test measurement are reported. Substantial correlations between the code expectation and the measured results are observed on relative resolution and distortion of the frame images. This tube has been integrated into an active framing camera system for field application.

We report a new method of fluorescence lifetime imaging that uses the ultra-fast optical temporal gate properties of parametric image amplification. Images with different lifetimes in the picosecond range are resolved with reliable and reproducible results. All these results are in good agreement with the lifetimes measured with a streak camera.