This article presents a concept of reconstruction of 3-D objects using non-invasive and touch loss techniques. The principle of this method is to display parallel interference optical fringes on an object and then to record the object under two angles of view. According to an appropriated treatment one reconstructs the 3-D object even when the object has no symmetrical plan. The 3-D surface data is available immediately in digital form for computer- visualization and for analysis software tools. The optical set-up for recording the 3-D object, the 3-D data extraction and treatment, as well as the reconstruction of the 3-D object are reported and commented on. This application is dedicated for reconstructive/cosmetic surgery, CAD, animation and research purposes.

The success of a 3-D television system requires that the observer fuses the corresponding left and right images comfortably, and that the depth resolution in the image satisfies the requirements of the specific task for which the system is employed. An investigation into the performance of 3-D TV systems has revealed that both the extent of the comfortable stereo- region and the minimum detectable depth-interval are related to, and may therefore be controlled by, the system geometrical and optical parameters. It is shown that the expressions defining such relationships form a useful basis in the design of a stereoscopic television system for a given application.

In this paper, we propose a new autostereoscopic display system employing an eye-position tracking technique. In this display system, the observable area of stereoscopic images becomes wide and an autostereoscopic display is realized by combining the tracking technique with computer graphic images. The wide 70-inch lenticular screen and HDTV LCD-projector generate more impressive 3-D images than conventional system.

New electro-optical schemes for display and projection system applications on the basis of cholesteric liquid crystals (CLC) are discussed. Reflective properties of CLC can be utilized to achieve controlled spectral selectivity through control of spectral distribution of polarizational states of the illumination. Low reflectant CLC-mirrors can be combined to form a resonator with higher reflectance. A chiral mirror is discussed with huge rotation of the polarization of reflected light. Fan-shaped distribution of color by polarizations turns out to be possible.

The most important size limiting parameters of an EL-display are the RC-time constants of the row and column lines, the power consumption arising mainly from the column electrode resistance, and the current capacity of the drivers. In this work the size limits have been analyzed by using circuit simulation methods. With the present standard brightness and resolution, a 1500.1000 20" - 25" display was found to be possible with the non-split structure. Still larger sizes can be manufactured by splitting the columns or rows. A display with both columns and rows split can still be made on a single substrate. With this structure over 40 inch diagonal EL-displays can be made.

Novel optoelectronic spatial light modulators with binary reflection phase gratings down to 1 micrometers are presented. The microlithographically produced gratings can be arbitrarily structured so that very fine gratings are achievable, e.g., linear, circular, or holographic gratings. Their phase modulation is controlled by a liquid crystal layer. Theoretical and experimental investigations have been done which show that a good modulation of the diffraction orders can be obtained. Applications of the modulators are the generation of 2-D and 3-D images and the realization of switchable holographic optical elements.

A light valve has been developed that is suitable for high performance video projection display applications. This device uses a chalcogenide photoconductor in a resistive mode switching configuration. Resolutions of greater than 1000 lines and video rate response times have been shown. Optical isolation of greater than 10⁷ and contrast ratios of 75:1 have been achieved. This paper also addresses the application of the light valve to a projector.

Flight instrument design has begun to include a new electronic technology for the display head: active matrix liquid crystal display (AMLCD). This is a significant design transition and applies across the board to complete cockpit modernization programs, individual instrument replacement projects, and new systems. AMLCD-based instruments are expected to have a substantially higher mean time between failure compared to both electromechanical and CRT- based instruments. Thus, the new technology will pay for itself. Furthermore, AMLCDs are truly sunlight-readable whereas CRT displays are not; it is mission critical that a pilot be able to see an instrument with the sun shining directly in the eye or onto the display. AMLCDs can also provide larger display areas enabling formats which increase situational awareness. As this is a new technology for the military, an industrial base for militarized AMLCDs must be created based on present research capabilities. The requirements for AMLCDs in DOD programs have been analyzed. Projects to build infrastructure and capacity are described. Applications include not only cockpits, but also digital map/GPS integrated displays for tank commanders and field laptop computers. We have the opportunity with this new technology to establish a common critical item product function specification for sunlight-readable, color and grayscale capable, flat panel displays for military applications. the Wright Laboratory is leading the development of such functional specification for U.S. military aircraft.

Given the rapidly rising complexity of advanced-development aircraft and the diminishing experience pool of crewstation designers, a requirement exists for the implementation of crewstation development tools. These tools must support real-time simulation, advanced displays, and empirical data collection. Northrop's Advanced Crewstation Integration Cockpit (ACIC) introduces full and rapid reconfigurability to a comprehensive aero-dynamic, threat, sensor and weapons system simulation presented to the pilot on conventional or advanced design displays. All controls and displays are reprogrammable, relocatable, and reconfigurable in their size, type of action, and graphical attributes. Development capability for expert systems, sensor fusion, and data collection requirements are provided for. This stand-alone system, operating in real time, is an industry first, unique in its ability to perform high utility simulation at low cost. Customized, unique performance metrics are both generated and supported by the ACIC.

With the development of helmet mounted displays (HMD) and night vision systems (NVS) for use in military and civil aviation roles, new methods of helmet development need to be explored. The helmet must be designed to provide the user with the most lightweight, form fitting system, while meeting other system performance requirements. This can be achieved through a complete analysis of the system requirements. One such technique for systems analysis, a quality function deployment (QFD) matrix, is explored for this purpose. The advanced helmet development process for developing aircrew helmets includes the utilization of several emerging technologies such as laser scanning, computer aided design (CAD), computer generated patterns from 3-D surfaces, laser cutting of patterns and components, and rapid prototyping (stereolithography). Advanced anthropometry methods for helmet development are also available for use. Besides the application of advanced technologies to be used in the development of helmet assemblies, methods of mass reduction are also discussed. The use of these advanced technologies will minimize errors in the development cycle of the helmet and molds, and should enhance system performance while reducing development time and cost.

An in-flight icing incident involving a BAe advanced turboprop (ATP) aircraft led to severe vibration of the airframe and a loss of aerodynamic control. During the period of vibration the pilot reported a specific pattern of image break up on the electronic flight instrument system (EFIS). Three experiments to investigate this visual effect are reported.

Virtual image displays are likely to become more prominent in the aircraft cockpit, the most common examples being the head-up display (HUD) and, more recently, the helmet-mounted display (HMD). There is however, a possibility that when using such a display the eyes may be inappropriately accommodated (focused). A series of experiments have been conducted in which accommodation responses were measured to a virtual-image display presented either in darkness or superimposed on a `real' scene. The results suggested that a number of people may focus inappropriately on displays of this sort, and that the problem is more pronounced if the user has to mentally process the virtual image. The consequences of such misaccommodation are potentially very serious, including misperceptions of the size and distance of objects in the `real' world, and a loss of contrast sensitivity perhaps resulting in low contrast targets being missed.

In modern warfare scenarios military helicopters have to be able to operate in NoE envelopes under all meteorological conditions. Under daytime good weather conditions this poses no problem for well-trained aircrews. In nighttime or bad weather conditions however the use of electronic sensors like IIT or TI is necessary. The aircrew use these devices for obstacle detection and avoidance and flight attitude perception. Flight below tree top level is only feasible when both of these tasks can be accomplished safely throughout the whole flight. For this reason the pilots must fly visual at all times. Relying on instruments for flight attitude control when flying between the trees would surely result in the striking of obstacles. These facts and the necessity for the aircrew to view greater azimuth angles than fixed wing pilots imply differing equipment and symbology packages for the two aircraft species. As a matter of fact only helmet mounted displays are really useful for helicopter flight control symbology. The following are results of experience from a number of trials with symbology in helicopters in low level flight down to 10 feet at night with IITs.

A `slow scan' CCD camera has been adapted for luminance and radiance measurement of displays used in night vision goggle (NVG) compatible aircraft. A video lightmeter offers several advantages compared to conventional test methods including high speed image capture and color coding of the digital image data. The color coding feature facilitates evaluation of the test display uniformity. Numerical values for luminance and infrared radiance are also extracted from the image data.

A high resolution (near 1000 l.p.i.) ferroelectric liquid crystal display operating at video rate has been demonstrated. The display uses a novel mode of matrix addressing which together with an improved drive scheme gives high speed and contrast. Details of the construction, optical properties, and drive electronics of the device are described. This new technology offers high pixel aperture ratios and wide angle of view; its suitability for both helmet mounted and direct view applications are discussed.

Fabrication of a wide field of view Head Up Display has required a trade off between performance and ease of manufacture. First generation holographic HUDs employed two distinct approaches: (1) Single element powered holographic combiner with a complex relay lens system. (2) Multiple element unpowered holographic combiners with a medium complexity combiner. The manufacturing difficulties of the first approach limit the achievable accuracy whereas the second approach, although easier to make, has obscuration and transmission problems. This paper describes an advanced HUD design using computer generated holographic construction techniques to fabricate a HUD which meets the extreme performance requirements of the latest aircraft but which remains a reasonable production item.

The Helmet-Mounted Display (HMD) concept is now widely used to meet the ever increasing mission requirements of modern helicopters especially for the very demanding tasks of night navigation, piloting, and use of armaments. However, a careful review of the system and ergonomic issues has to be undertaken in order to define a product that will be accepted by the aircrew and efficient in the battle field environment. Special attention must be paid in the specifications and implementation of the image sensors used to display the external scene in front of the eyes of the aircrew members. A technical approach, including various designs and the most significant performances, is described.

From a physiological point of view, HMDs presenting an image on each eye are known to offer some advantages comparatively to monocular presentation. Besides the obvious fact that a binocular display provides more `natural' visual perception, it also prevents rivalry and improves several components of the visual function, such as perceptual threshold, contrast sensitivity, and visual acuity. Binocular vision is also a crucial element in depth perception, though its main characteristic, stereopsis, is not yet really used. However, these advantages must be paid by an increased technical complexity and added weight on the head, raising safety related concerns, but also comfort and operational (performance) issues, which imply several tradeoffs. An R&D program funded by the French MOD currently aims to build a night attack HMD for experimental flight tests. Human factor basic requirements were to achieve a head supported mass below 2 kg with minimum encumbrance and to project imagery and symbology on the helmet visor with a large Field of View. The optical and mechanical design was first optimized to allow a head/system resultant CG within the safety limits for ejection. Considering experimental results, a tradeoff is made favoring head mobility rather than seeking stability. Two miniature CRTs are used to display imagery coming either from IR, I² or TV sources, while symbology is projected monocularly. Consideration of operational needs also implies several tradeoffs at this level.

EUROCOPTER has been under contract to the French and German ministries of defence for five years to develop the TIGER, a second generation anti-tank helicopter. A piloting thermal imager has been installed on a steerable platform in the helicopter nose in order to achieve the possibility of flying round the clock. In addition to this sensor, which is sensitive at a wavelength of 10 micrometers , the German side has proposed using an Integrated Helmet System in the PAH 2. This helmet, manufactured by GEC-Marconi Avionics, incorporates two cathode ray tubes (CRT) and two image intensifier tubes which allow the pilot to use an additional sensor in the visible and near infrared spectrum. The electronic part will be built by Teldix. EUROCOPTER DEUTSCHLAND has received the first demonstrator of this helmet for testing in the EUROCOPTER Visionics Laboratory. Later, the C-prototype will be integrated into a BK 117 helicopter (AVT Avionik Versuchstrager). This new helmet has a field of view of 40 degree(s), and exit pupil of 15 mm and improved possibilities of adjusting the optical part. Laboratory tests have been carried out to test important parameters like optical resolution under low light level conditions, field of view, eye relief or exit pupil. The CRT channels have been tested for resolution, distortion, vignetting and homogeneity. The requirements and the properties of the helmet, test procedures and the results of these tests are presented in the paper.

Helmet mounted displays optimized for night flying are now available from several manufacturers as are HMDs optimized for day applications. In general day and night operations require HMDs with different attributes. However, many mission scenarios require the HMD to be used in both day and night conditions in the course of a single mission and therefore require the HMD to provide a 24 hour capability. This paper describes designs solution for 24 hour HMDs for both fixed wing and rotary wing applications, using current state of the art technology.

Helmet Mounted Display for daytime missions should have large field of display, as well as undisturbed see-through vision. These requirements naturally lead to the use of the helmet visor as a display combiner. Previous projects were based upon non-spherical, mostly parabolic, tilted combiners. These optical projecting systems suffer from relatively large keystone distortion. This work presents a new optical concept for compensating the distortion, using a spherical surface as an optical combiner coupled to a complementary aberrative relay system.

Photoluminescent (PL) spectra of SnO₂, In₂O₃, Y₂O₃, Yb₂O₃, CaO oxides and their mixtures, doped with rare-earth ions have been studied. The possibility of their use for electroluminescent (EL) displays was considered. It is shown, that under Ar laser excitation of the luminescence one can get display color range from green to red. PL spectra of oxides with Eu³⁺ are characterized by the substantially greater set of emission lines than for the oxides with Ce³⁺. It indicates that the degeneracy of ⁷F_1,2 levels in Eu³⁺ luminescence centers is removed. Raman spectra studies have been allowed to identify the impurity ion Eu³⁺ symmetry in oxide matrices. It corresponds to the C_3v group. The ion Ce³⁺ symmetry under substitution In³⁺, Sn²⁺, Y³⁺ for Ce³⁺ in the oxide lattice is substantially higher than C_3v, therefore, the PL spectrum contains only two lines in the visible range, and their energy position slightly depends on the oxide matrix type.

Spatial light modulators (also called light valves) are useful in projection and display applications. Much research is being conducted today worldwide to improve capabilities in both applications. This review article enumerates some ongoing developments, while providing a background on spatial light modulators.

The field hysteresis of the cholesteric-nematic transition (CNT) in mixtures with small (up to 2 weight%) maintenance of optically active material is being researched. It is shown that the relative magnitude of the loop of the hysteresis and (delta) U depends on the ratio d/P, (gamma) equals (root)K₂₂/K₃₃ and surface free energy. In the case of fixed magnitude of the surface free energy the ratio of constants of the elasticity and of the liquid crystal material gives a substantial magnitude of the constructive parameters of the display d/P_o, which gives us a maximum of the (delta) U. The influence of the temperature dependence of the constants of the elasticity and step of the induced spiral on the temperature dependence (delta) U takes place.

The advances in the technology of high performance polygonal scanners, both for laser beam typesetting and the projection of computer generated images, meet the requirements for laser beam projection of high definition television (HDTV) onto large screens; screen widths in the order of 30 meters (approx. 100 feet). This paper illustrates the interrelationship between the scanned image quality resolution for laser beam projected TV and HDTV, and the scanner design and manufacturing tolerances -- spatial and temporal. It provides a guideline for systems' designers to calculate and trade-off the specification tolerances for a polygonal scanning subsystem.

Matrix addressed liquid crystal (LC) light valves are exerting an ever increasing presence in both direct-view and projection mode display sectors. In transmissive mode the periodic structure of the matrix, when used in conjunction with a backlighting source capable of temporal and spatial modulation, offers the capability to obtain autostereopsis in a useful and economic fashion. This novel combination of complex and proprietary illumination mechanisms with matrix addressed LC valves has been researched and practically validated by the author and various useful configurations defined. From this it has been established that stereoscopic displays can be obtained without either compromise to display surface resolution or requiring the viewer to employ complementary optical devices. The work performed to date has further confirmed that such display constructs may be usefully applied to direct view, projection mode, and helmet mounted systems to the net benefit of operator performance.