The projection display industry is now a multi-billion dollar market comprising an expanding variety of technologies and applications. Growth is being driven by a combination of high volume consumer products and high value business demand. After many years of marginal, but steady performance improvements, essentially all types of projectors have crossed the threshold of acceptability and are now facing accelerated continuing growth. Overall worldwide unit sales of all types of projection displays for all applications will nearly double from 1.6 million units in 1996 to 2.8 million units in 2002. By value at the end user price, the global projector market will grow modestly from 6.3 billion dollars in 1996 to 7.7 billion dollars in 2002. Consumer television will represent the largest share of unit consumption over this time period; in 1996, this application represents 72 percent of the total unit volume. The second major application category for projection displays is the business or presentation projector, representing only 14 percent of the unit shipment total in 1996, but 50 percent of the value.

The influence of the Eidophor projection system has been felt for over fifty years, providing users with extreme brightness and unique capabilities in a wide variety of applications. The Eidophor, manufactured by Gretag AG, Switzerland, is an oil layer light valve system invented in 1943 and is still unsurpassed in brightness by any other technology. Although the technology is over 50 years old, there are still many viable uses for the system, particularly in North America. This paper will review the history, technology, applications and outlook for the Eidophor projection system. The applications include permanent locations such as sports arenas and television studios as well as a continuing impact in the large screen display rental community.

The educational, business and military community has indicated a need for information dealing with the performance of projection equipment. Systems which present pictorial and alphanumeric video information to groups are well known. Many technologies are available, each with characteristic performance for brightness, resolution and color rendition. The end-user is primarily interested in the perceptual quality rather than what technology is used. The fixed and variable resolution standards address this need by providing a specification to describe parameters and performance characteristics that allow one to compare fixed or variable resolution systems in a meaningful way. Results should be available with a minimum number of measurements and expressed in common terms. These standards deal only with test methods and specifying terms for basic characteristics of front and rear projectors. This standard also could be applied to fixed resolution systems such as overhead projectors with LCD based data displays.

The rapid development of solid-state lasers in al three primary colors has opened up the possibility of new electronic displays. Many of the limitations of light-valve displays are eliminated if laser-light sources are used. Other light-valve options can only be realized using laser sources. This paper will describe some of the more advanced options for the laser and show how these can be used to obtain high-performance electronic displays.

An LC-projector usually contains 3 monochrome TFT-LCDs with a 3-channel dichroic system or a single TFT-LCD with a micro color filter. The liquid crystal operation mode adopted in a TFT-LCD is TN. The optical throughput of an LC-projector is reduced by a pair of polarizers, an aperture ratio of a TFT- LCD and a color filter in a single-LCD projector. In order to eliminate absorption loss by a color filter, a single LCD projection system which consists of a monochrome LCD with a microlens array and a color splitting system using tilted dichroic mirrors or another optical element such as a holographic optical element or a blazed grating has been developed. And LC rear projection TVs have started to challenge CRT-based rear projection TVs. In addition to this system, new technologies to improve optical throughput have been developed to the practical stage such as an active- matrix-addressed PDLC and a reflective type LCD on a Si-LSI chip. Merits and technical issues of newly developed systems and conventional systems including a-Si TFT-LCDs and p-Si TFT-LCDs are discussed mainly in terms of optical throughput.

Compact LCD projectors require a high efficiency light source that has the smallest possible spatial extent. The objective of the lamp design must be to preserve the system etendue to ensure excellent screen illuminance. We present the results of the development of projection lighting systems that produce 1,500 to 3,000 lumens, have luminous efficacious of >= 1m/W and source sizes of <EQ 1.2 mm. Results of statistically designed experiments on the lamp design parameters and design parameters of the lamp/ballast systems essential for rapid start, restart, and long life will be discussed. These design studies result in compact efficient systems. 3D luminance results - both model and experiment - will be discussed. The result of our studies is a better understanding of the factors impacting long life, high efficiency, metal halide lamps with very small source sizes. We have identified a series of designs for lamp/ballast systems that give the user an option of performance sets. We will describe recent work on the design and characterization of a long life 50 Watt, 1.2 m arc gap metal halide lighting system that produces 3,200 lumens. A theoretical characterization of the optical efficiency of an arbitrary projection optical system through discussion of the arc efficiency and the system etendue will be presented.

In this paper, works on optimization oflight sources for small format projection systems are reported such as DMD, TRLCD, and ITT systems. Results using short arc Xenon lamps versus modest gap width HID and relatively long gap width RID lamps are compared with several designs of the Compound Orthogonal Parabolic Reflector (COPR®), reflector systems, and with relatively deep elliptical reflectors. It can be shown that the diameter ofthe COPR® reflector is independent of the resulting focal spot size, but the gap width is a function ofthe spot size. For intensity or total light for a given iamp, the COPR® is 60% better than the elliptical reflector. If aperture size is not important, than the comparison is moot. A new concept of imaging ray tracing versus classical point and ray emission method are compared specifically for the evaluation of relative intensity of "light" through a given aperture dimension. It can be demonstrated that the imaging method is much more efficient to provide first order results for optical designers. A hyperboloid ray concentrator is introduced as a method to relax the small aperture requirement for small format imaging systems. Cost trade-off will be provided on typical, currently available lamps.

We present a model based on the coupled mode theory and use this model to analyze the diffraction properties of volume holographic diffusers, such as the diffraction efficiency and wavelength sensitivity. Volume holograms of both transmission type and reflection type are analyzed. Besides typical behaviors of Bragg diffraction, we notice several interesting phenomena. For transmission gratings with small diffraction angles, our results predict that the diffraction efficiency exhibits a blue-shift for its maximum value and a dip at the recording wavelength. Also presented is the enhancement of wavelength tolerance for a thin holographic medium, which can serve as a wideband diffuser over the entire visible range. For a thick medium, the wavelength- multiplexed volume holograms recorded with three primary colors, red, green, and blue, are studied, which provide an effective and feasible means of diffusion for color displays.

Rear projection screens of light valve systems will be significantly different from existing screens used in consumer CRT rear projection sets. Artifacts such as speckle and more stringent requirements for resolution will direct the development of light valve screens. In this paper, we will give a mathematical analysis of the origin of speckle and will describe systems that were developed to measure the speckle contrast and the resolution of the screen in the presence of speckle. We will describe new screen designs that reduce the speckle contrast to an acceptable level while maintaining specifications for gain and resolution.

The optical efficiency of a single-LCD projector can be improved by 'spatio-chromatic illumination' method. It consists of an angular separation of the three primary colors combined with a focusing of each color in the corresponding pixel by a microlens array. To perform the spatio-chromatic illumination we present two innovative systems based on volume holographic components. The dispersion property of these components realizes the angular separation of the primary colors, the focusing being performed either by classical or holographic microlens. A complete luminous efficiency analysis of spatio-chromatic illumination with volume holographic elements is reported. The luminous flux analysis will take into account etendue limitation considerations. Experimental results will be given for a prototype of single-LCD projector using a volume holographic grating.

We report on recent progress in the development of anew liquid crystal color shutter technology that provides high throughput and saturated color. These devices, when combined with high frame rate displays or imagers, convert monochrome to color using the sequential color technique. The current focus is on designs that are compatible with low cost nematic liquid crystal switches.

Displays based on diffraction effects can provide very high lumen output at high contrast ratio, due to the absence of polarizers, low losses, large-area light valves, and bright light sources. The electron-beam addressed oil-film diffracting light valve employed by the Eidophor is an expensive technology. Recent developments in diffraction form liquid-crystal devices, micromechanical gratings, and elastomeric deformation, could result in a low-cost high- efficiency projector. Therefore, it is of interest to examine the performance limitations of diffractive systems in general, and in relation to other systems. The throughput efficiency of a projector is related to the light source collimation required to transmit light through the limiting apertures of the system. A diffractive device expands the optical divergence, and consequently sacrifices system optical throughput. If the source collimation is increased by the availability of short-arc lamps, or laser diodes, the diffractive throughput penalty is reduced or eliminated. The performance of micromechanical and liquid-crystal diffractive structures is analyzed using a realistic arc lamp model. Theoretical limitations on projector throughput and contrast ratio are derived for diffractive systems, and compared with polarization dependent liquid crystal systems.

End-to-end modeling of the photometric performance of LCD projection system using Monte Carlo geometrical ray tracing methods is an accurate and precise tool for predicting and improving the performance of these deices before, during and after product development. However, an accurate simulation first requires considering which physical properties contribute most to the system's photometric performance. Second, these properties must be characterized by physical measurements and translated into the tangible modeling parameters of a ray tracing program. Third, the implications of using a Monte Carlo ray tracing algorithm, and in general any other optical transformation algorithm, on radiometric accuracy must be well understood. These considerations as well as a generalized approach to the characterization and simulation of an LCD projector are described. A commercially available ray tracing program, the Advanced Systems Analysis Program, is used to demonstrate this approach. The irradiance uniformity, CIE color performance and screen brightness of an arc source LCD projector system are computed as an example.

Although many images are handled in the medical filed, image monitoring deices and filing methods vary due to differences in resolution and pixel depth. If a system enabling such images to be filed synthetically without losing its quality were to exist, and if retrieval of such images were made easily, such a system could be applied in various ways. In order to determine whether a super high definition (SHD) image system running at a series of 2048 resolution X 2048 line X 60 frame/sec was capable of such purposes, we established a filing system for medical images on this system. All images of various types produced form one case of cardiovascular disease were digitized and registered into this filing system. Images consisted of plain chest x-ray, electrocardiogram, ultrasound cardiogram, cardiac scintigram, coronary angiogram, left ventriculogram and so on. All images were animated and totaled a number of 243. We prepared a graphic user interface for image retrieval based on the medical events and modalities. Twenty one cardiac specialists evaluated quality of the SHD images to be somewhat poor compared to the original pictures but sufficient for making diagnoses, and effective as a tool for teaching and case study group purposes because of its operability of the retrieval system. The system capability of simultaneously displaying several animated images was especially deemed effective in grasping comprehension of diagnosis. efficient input methods, and creating a capacity of filing all produced images are future issue.

The basic performance of a projection system using a diffraction-based liquid crystal spatial light modulator is studied. First, the relationship between the modulation pattern of light at the SLM and its diffraction pattern is analyzed using the scalar diffraction theory, and anew method for improving the contrast of the projected image is proposed on the basis of this analysis. Then, the optical efficiency and image contrast are estimated by numerical calculations, in which monochromatic illumination incident on the SLM at a certain angle range is assumed. Both an efficiency of 0.65 and a contrast of 200 are obtained at the same time by optimizing the modulation pattern and apertures in the projection optics. The possibility of realizing a projector delivering bright images with a high contrast is suggested.

The grating light valve (GLV) technology is a micromechanical phase grating. By providing controlled diffraction of incident light, a GLV device will produce bright or dark pixels in a display system. With pulse width modulation, a GLV device will produce precise gray-scale or color variations. Built using micro electromechanical system technology, and designed to be manufactured using mainstream IC fabrication technology, the GLV device can be made both small and inexpensively. A variety of display systems can be built using GLV technology each benefiting form the high contrast ratio, fill ratio, and brightness of this technology. In addition, GLV technology can provide high resolution, low power consumption, and digital gray-scale and color reproduction.

The structure and principle of operation of a ferroelectric liquid crystal - over - CMOS silicon display are described. Several addressing schemes for creating full color images are introduced and assessed. Preliminary results using 176 X 176 pixel and 512 X 512 pixel DRAM displays are presented.

Projectors based on polymer-eNCAPsulated liquid crystals can provide bright displays suitable for use in conference rooms with normal lighting. Contrast is generated by light scattering among the droplets, rather than by light absorption with crossed polarizers. We have demonstrated a full-color, compact projector showing 1200 ANSI lumens with 200 watts of lamp power - a light efficiency of 6 lumens/watt. This projector is based on low-voltage NCAP material, highly reflective CMOS die, and matched illumination and projection optics. We will review each of these areas and discuss the integrated system performance.

One of the most difficult problems of large-screen projection displays is overloading of a panel to be projected with illuminating light. The problem can be solved by using, on the way from a panel to be projected to a screen, an optical amplifier with high enough amplification. The prospects of using laser amplifiers in projection displays are discussed. Among all laser amplifiers the most suitable for application as optical amplifiers in projection systems are now pulsed metal vapor laser and metal halide laser amplifiers. They have rather high gain enabling amplification in the range from 10² to 10⁴ and high average output power sufficient to illuminate a large screen. The main characteristics of these amplifiers are described. The results of experimental investigations of projection systems with copper, copper bromide, gold and some other metal vapor amplifiers are reported. In all cases good quality amplified images were obtained. Average power at the output of amplifiers was under typical conditions of operation comparable with the output power of a laser with the same amplifying element. Measurement of contrast of amplified images showed that under normal conditions of operation it is close to the contrast of the input picture even at strong saturation of the amplifying medium. The influence of the amplifier saturation is briefly discussed. The results of experiments with TV projection systems using two types of liquid crystal spatial light modulators are presented and prospects of large-screen projection displays development are discussed.

A novel laser projection display utilizing an optically addressed spatial light modulator (OASLM) is presented. The OASLM is based on the photochromic protein, bacteriorhodopsin, immobilized in a thin gelatin film. The photochromism of this material facilitates the light-induced switching of the optical absorption properties of the film. In this manner, the film can dynamically be switched between a purple- and yellow-colored state within 50 microsecond(s) . Furthermore, this material is capable of more than 10⁸ read-erase cycles without showing any sign of fatigue. This monochrome system is very suitable for radar displays, due to the high contrast of the projected images. Other possible applications include public information displays in airports and railway stations. The advantages of this projection system can be summarized as; (1) flicker-free graphics due to the temporal response of the OASLM causing no eye fatigue, (2) due to the molecular nature of the photochromic process, the spatial resolution is only limited by the scanners and projection lens, (3) as a result of the dynamic process in the OASLM, the system can be used at different ambient light levels by simply altering the intensity of the write laser and the read projection lamp simultaneously, (4) highly efficient use of the power from the projection lamp because it is actively pumping the photochromic process.

Floating Images, Inc. has developed the software and hardware for anew, patent pending, 'floating 3D, off-the- screen-experience' display technology. This technology has the potential to become the next standard for home and arcade video games, computers, corporate presentations, Internet/Intranet viewing, and television. Current '3D Graphics' technologies are actually flat on screen. Floating Images technology actually produce images at different depths from any display, such as CRT and LCD, for television, computer, projection, and other formats. In addition, unlike stereoscopic 3D imaging, no glasses, headgear, or other viewing aids are used. And, unlike current autostereoscopic imaging technologies, there is virtually no restriction on where viewers can sit to view the images, with no 'bad' or 'dead' zones, flipping, or pseudoscopy. In addition to providing traditional depth cues such as perspective and background image occlusion, the new technology also provides both horizontal and vertical binocular parallax and accommodation which coincides with convergence. Since accommodation coincides with convergence, viewing these images doesn't produce headaches, fatigue, or eye-strain, regardless of how long they are viewed. The imagery must either be formatted for the Floating Images platform when written, or existing software can be reformatted without much difficult. The optical hardware system can be made to accommodate virtually any projection system to produce Floating Images for the Boardroom, video arcade, stage shows, or the classroom.

Last year, we reported a novel phenomenon of voltage-induced color-selective absorption with surface plasmons. When a white light is incident on a metal/EO material interface, in certain condition, surface plasmon waves can be excited; those photons in surface plasmon resonance wavelength range would be totally absorbed and these photons out of the surface plasmon resonance wavelength range would be almost totally reflected. This surface plasmon resonance depends on the dielectric constants of both the metal and the EO material. If a voltage is added on the EO material to change its dielectric constant,the surface plasmon resonance spectrum can be shifted from one wavelength to the other, and this is a tunable notch filter. If coupled surface plasmon waves are used, a tunable bandpass filter can be built. A prototype mode has been built using liquid crystal as the EO material. Experiment results, which has excellent agreement with theory, has shown that the wavelength tunable range can cover almost all of the visible when 30-v voltage is applied. Theoretical calculation has shown that this tunable filter can also work in IR range up to at least 10 micrometers .

We present a novel fast bistable nematic cell with intrinsic grey scale. The geometry of a single pixel is the usual sandwich one, with tow conductive flat plates that contain a film of nematic material with positive dielectric anisotropy. An electric field is applied perpendicularly to the boundary plates. This novel deice works by controlling the creation and the erasure of surface defects on a suitable surface when the applied electric field is strong enough to achieve the anchoring breaking condition: (xi) equals L, where (xi) is the coherence length of the electric field and L is the anchoring extrapolation length. Note that these surface defects should disappear onto a usual monostable substrate, due to topological constraints. Particular surface conditions are required to stabilize them. The surface defects depolarize the incident light and, as their density can be modulated, a grey scale can be achieved. Up to now, the maximum measured optical contrast is 200:1. The typical writing and erasing voltages are in the order of 50 Volts for a pulse length of 50 microsecond(s) ec on a sample of 5 micrometers thickness.

The market of television displays is an area of outstanding economical importance due to its annual production volume of more than 100 million TV tubes. 15 Million TV sets were produced in Western Europe in 1993 alone. On the other hand the materials used in the tubes and the energy consumption for production and during operation are issues of great ecological importance. It is therefore of social and political interest to achieve simpler and ecologically compatible solutions through new technologies and innovative technical concepts. Displays with a diagonal of one meter or more for TV and computer monitor applications operating in accordance with HDTV or higher formats require technology that is either not available or too costly. Conventional television tubes would not only have to be very large, the high internal pressure would entail an extraordinary mechanical stability of the tube, resulting in a notable increase in weight. Flat LC-displays present another alternative. Today as in the near future, only high performance colour LCDs with relatively small physical dimensions will be produced due to the complex technology involved. Furthermore, there are technical inadequacies when it comes to brightness and contrast in daylight or under oblique viewing angles. There are no solutions in the offing for these problems. A third possibility is the enlarged projection of pictures produced either by LCDs or similar techniques. In this case daylight projection can also pose problems due to the lack in definition and brightness. The most promising technique for a high brightness, high definition and large area displays are based on the direct projection with laser beams. Presently not satisfying solutions are available for 2 basic parts of this technique: the low-cost laser sources needed for a colour TV projection and the simple deflection system delivering the required number of pixels. There is a world-wide effort concerning the development of suitable light sources. We propose the development of a deflection system based on a novel simple electro-optical deflector fabricated in LiNbO3.

Newly developed high sensitivity and high resolution photoactivated liquid crystal light valves enjoy an enormous advantage with regard to supporting multi-megapixel display formats. Using multiple optical drivers, for example six polysilicon 800 X 600 pixel AMTFT devices, allows for the provision of very high brightness 2400 X 1200 pixel images. The use of linearly scanned, multiple ELD devices, take the format into the six million to eight million pixels capability that is truly needed to satisfy the capabilities of the human visual system. Our work details applications in CAD/CAM, simulation, digital cinema and the workstations of the future.

Electronic projection display technology for high-brightness applications had its origins in the Gretag Eidophor, an oil film-based projection system developed in the early 1940s. A number of solid state technologies have challenged the Eidophor, including CRT-addressed LCD light valves and active-matrix-addressed LCD panels. More recently, in response to various limitations of the LCD technologies, high-brightness systems have been developed based on Digital Light Processing technology. At the heart of the DLP projection display is the Digital Micromirror Device, a semiconductor-based array of fast, reflective digital light switches that precisely control a light source using a binary pulsewidth modulation technique. This paper describes the design, operation, performance, and advantages of DLP- based projection systems for high-brightness, high- resolution applications. It also presents the current status of high-brightness products that will soon be on the market.