The first part of the work is devoted to the problem of computer simulation of static image intensifiers and streak
image tubes. The most peculiar and sensible points of the simulation, such as image curvature surface, aberration
coefficients, spatial and temporal resolution along the work area, are illustrated on typical examples. The problem of
image curvature correction is discussed as well.
The second part of the work outlines the theoretical grounds and results of computer-aided design of a principally
new photoelectron-optical system with time-depending fields capable of essential compressing of electron bunches for
the needs of time-resolved electron diffraction (TRED) experiments. Some recent experimental results on the bunch
compressing obtained with the newly designed and manufactured photoelectron gun are presented.
Some theoretical milestones, in definite sense summarizing our studies on temporal compressing of photoelectron
bunch with time-depending electric fields, are elucidated. The recent experimental results on dynamic compression of
photoelectron bunches of picosecond duration, gained with the use of a newly designed photoelectron gun employing the
electric field ramp of about 1.5 kV/ns, are presented and compared with the results of computer simulation.
Basing on perturbation technique, discussed are some urgent problems of computational charged particle optics
including numerical evaluation of fringe fields and field perturbations caused by small deviation of the shape of
electrodes from rotational or planar symmetry as well as aberrational analysis of charged particle beams in the most
general tensor form.
It is shown that perturbation technique, being combined with other numerical approaches such as the tau-
variations method and generalized method of initial parameters variation, proves to be most promising for evaluation of
mechanical tolerances and simulation of Coulomb repulsion effects and charged particles scattering upon a fine-structure
grid.
An outline of the thermal vision systems curriculum for 5th year undergraduate students at the Branch of Department of Electro-Optical Devices, the Moscow State University of Geodesy and Cartography (MIIGAiK) attached in Central R&D Institute "Cyclone" is presented. Contents and some methodological aspects of the course "Thermal Vision Systems" teaching are described.
In the paper, theoretical and numerical studies on temporal focusing of photoelectron bunch in time-dependent fields are continued. Presented are the results of computer modeling on electron-optical system with combined time-dependent electric and static magnetic fields to ensure both spatial focusing and temporal compressing of photoelectron bunch down to sub-femtosecond level. The peculiarity of space charge effect contribution to the bunch broadening in the case of time-dependent electric field is discussed.
The generalized computer model of electro-optical systems COMOS has been used for the predicting and analyzing the performance of thermal imagers (TI). The identity of calculation and experimental target range performance tests was satisfactorily enough
The paper is devoted to the problem of temporal resolution in electron-optical streak tubes intended for ultrafast processes investigation. The temporal threshold of about 150-200 femtoseconds can be hardly overcome without a principally new approach to the design of electron-optical scheme of such tubes. One of the possibilities, namely the use of a photocathode having rather fine grid structure, is numerically analyzed on the basis of 3D field calculations.
In the paper new theoretical aspects of temporal focusing of photoelectron bunch in time-dependent fields are elucidated. The results of computer modeling on electron-optical system with combined time-dependent eletric and static magnetic fields which ensure both spatial focusing of the bunch and its temporal compressing up to the sub-femtosecond level are presented.
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.
In laser scanning devices using a projection method of measurement a narrow laser beam moves parallel to itself. If the velocity of scanning of the plane of the object under control is constant then the duration of the video signal which is formed behind the object will correspond to the object’s size lengthwise the direction of scanning. If the object is not flat the duration of the video signal will not correspond to the size of the object due to the fact that in the process of its formation there takes part the beam reflected from the surface of the object under measuring. Thus the error appears in the result of measurement. The error which depends on the object’s configuration and reflectivity may be rather significant. The formula of calculation of the error as a function of the object’s surface curvature and height of microroughness of the surface is presented in the work. There is suggested the way of compensation of the error which consists of covering synchronously to the movement of the scanning beam and by turns the halves of the sensitive areas of the bielement photodetector located symmetrically to the optical axis.
The absorption of IR-radiation 200-4000 cm-1 range of 0,65-1,9 micron thick polyimide thin-films with such functional coverings as titanium, silicon nitride, aluminium was investigated. The 1,3-1,4 micron thick polyimide structure have 85% absorption of IR-radiation of 720-1250 cm-1 range. On the base of the developed polyimide thin-film technology linear micro bolometric array detectors was fabricated and investigated. Calculated value of the linear micro bolometer array detectivity is 4×107 cm Hz1/2W-1.
It is shown that the simulation problems originated in femtosecond photoelectronic imaging in the beginning of 80s resulted in the development of a new aberration approach called 'the tau-variation technique.' The approach proves to be most fruitful for computer electron optics of non- stationary electromagnetic fields, and at the same time allows unifying the aberration theories of narrow and wide beams. The results illustrating new features of 'ELIM/DYNAMICS' Package specially oriented to the problems of femtosecond imaging are considered, and some aspects of the unsolved computer problems closely connected with femtosecond photoelectronic imaging are thereupon outlined.
Two different approaches to image tube computation, numerical optimization and design being developed in GPI (Russia) and BIT (China) are presented and comparatively discussed as applied to a Russian-made streak image tube.
A new approach to solve the self-consistent problem for electron gun with arbitrary-shaped cathode is suggested. The main feature of the approach is that the most effective numerical techniques of charged particle optics, namely finite-difference and integral equation methods for field calculation on the one hand, and direct ray-tracing and aberration analysis for trajectory calculation on the other, are integrated within a versatile iterative procedure. Some testing problems are considered and analysed in details.
KEYWORDS: Laser scanners, Laser systems engineering, Control systems, Mirrors, Error analysis, Prisms, Beam controllers, 3D scanning, Scanners, Optical scanning systems
Due to inconstant velocity of movement of laser scanning beam in the plane of measuring as well as due to defocusing brought by the scanner there is possible the appearance of rather meaningful errors. Formulas and diagrams for these errors' calculations are derived.
The paper summarizes the results on developing and testing numerical algorithms and software for computer modeling of emission electron beam devices. As examples, some numerical experiments carried out with the newly developed Applied Program Package `CHARGE' are presented and discussed.
The paper is devoted to software development for simulation, optimization, and computer-aided design of photo/thermo- emission electron optical systems and units. The first part of the paper presents the applied program package (APP) 'ELIM\DYNAMICS\ intended for computer-aided design of dynamic photo-emission image tubes with electro/magnetostatic focusing and deflection (streak tubes). The developed software allows highly precise computation of basic image quality characteristics both in static and streak modes. One of the main advantages of the new program version presented is that 'through' electron beam computation from the photocathode to image receiver is available with regard to dynamic aberrations caused by scattering fields located nearby the edges of deflecting plates. In the second part, the possibility is shown to generalize some numerical techniques being effectively applied in photo-emission imaging electron optics (namely, the (tau) -variation -- and the first kind integral equations techniques) to simulation of the thermo-emission electron beam technology units. Functions of the new APP 'CHARGE' are presented, and some numerical aspects of the self-coordinated problem are discussed.
Applied program package ELIM\DYNAMICS\ is designed for simulation, optimization and computer-aided design of dynamic image tubes with electrostatic focusing and deflection. The package allows highly precise computation of basic electrical and electron-optical characteristics including spatial/temporal line spread functions, spatial and temporal resolution along the photocathode working area in static and streak modes, spatial and temporal scale distortion, as well as assembling tolerances associated with image errors due to weak disturbances of axial symmetry. One of the main advantages of the new version presented is that `through' computation of electron beam from photocathode to screen is available with regard to dynamic aberrations caused by scattering fields located nearby the edges of deflecting plates. Some examples of image tube computations made with ELIM\DYNAMICS\package are given.
A new theoretical line of attack to solve the self- coordinated problem in charge particle optics is developed basing on the aberration theory and (tau) -variation technique. The self-coordinated problem is treated as initial-value problem for the evolution integro-differential equation which directly follows from the Lorentz equation with taking into account the space charge effects. The Coulomb potential of a beam is presented in the form of integral taken over the initial parameters domain, and the induced potential (the `mirror image' potential) is presented in the convolution form with a Green function satisfying the adjacent Fredholm integral equation of the first kind. Some considerations to numerical solution of the evolution equation obtained are applied.
New nonlinear optical crystal--the octahydrate of aluminium iodate Al(IO3)3 (DOT) 8H2O were grown from multicomponent aqueous solution. Linear and nonlinear optical properties of Al(IO3)3 (DOT) 8H2O crystal have been measured and compared to those of the lithium iodate crystals. The nonlinear optical merits of other iodates have been predicted.
The results of many-years activity in elaboration of numerical techniques and software for static and dynamic image tube design are presented. The developed software is based on the first kind integral equations technique, aberration theory, and special algorithms which allow high-precise image quality computation. The software was carefully tested and used in numerous calculations for spatial and temporal parameters of image tubes operating in static and dynamic modes. Some examples of these calculations are graphically presented and discussed in details.
Studying the optimum performance of molecular lasers requires information.on active medium parameters. Those in case of laser are translational and vibrational temperatures T, T1 , T2, T3' , and lasing molecule concentration., n. Vibrational temperatures have previously been determined in series investigations of electro discharge CO—laser active medium234S. But definition of concentration n potentially associated with large errors due to lack of lower laser level's vibrational temperature T1 measurements. Other temperatures have been estimated according to approximate model. As it was theoretically shown6 , to determine the inverse medium parameters without simplification, one should measure the small signal gains for lines of (0001_1000) and (0001_0200) traditional CO2 bands, (0002_1001) second sequence band and (O1'l-ll'O) hot band. Translational and vibrational temperatures and lasing molecule concentration were defined for CO—laser using the small signal gain measurements and theoretical scheme6.
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