The explosive growth in sales of projection displays began only five years ago with the commercial introduction of microdisplays, small electronic imagers. The microdisplay packs the imaging capability of a television or computer monitor into an integrated circuit chip and is a disruptive technology, representing a breakthrough in performance and price when compared with alternative direct view displays. Microdisplay based projectors for conference rooms have already had a dramatic impact on the presentation market with unit volume approaching 500,000 systems and factory revenues exceeding $2 billion in 1997. But the revolution has just begun. New front projection systems with much higher light throughput will fuel the growth of systems designed for board rooms and large venues. New small, light weight, portable projectors, weighing less than 10 pounds, targeted at road warriors, will open up yet another segment of the presentations market. During the next few years, further improvements in the performance and pricing of microdisplays, coupled with higher performing lamps, optics, and electronics will enable microdisplay based projectors to penetrate the mainstream television and monitor markets. Microdisplay based rear projection displays will compete head to head with CRT based displays for big screen, high definition dominance. Higher definition and cheaper microdisplays are a key requirement for the expansion of projection display applications. First generation technology microdisplays are based on two competing technologies: The first, a transmissive imager, combines an active matrix integrated circuit backplane made with poly-silicon on quartz technology with a twisted nematic liquid crystal front plane (p-Si/TN); the second, a reflective imager, uses a crystalline silicon backplane circuit to activate microelectromechanical mirrors (Texas Instruments digital micromirror device, the DMDTM).'6 Both of the established competitive microdisplay designs are challenged when it comes to delivering a higher definition image at a lower price.24 Price reduction will flow primarily from reducing the size of the microdisplay imager. But size and cost reduction necessitate smaller pixel sizes, especially for high definition imagers, and current costs for both the p-Si/TN and DMD devices limit their use to systems with selling prices of more than $3,500.00. A number of developers are introducing a second generation of microdisplays that use CMOS active matrix backplanes in combination with reflective liquid crystal front planes (c-SiJRLCD). Such devices hold the promise of further breakthroughs in performance and price.14744 Microdisplays of about the same size and cost as the established devices hold the promise of higher definition displays for both the presentation market as well as high definition television. Smaller and cheaper cSi/RLCD high definition microdisplays promise to open up new markets for rear projection desktop monitors and PCTVs.'2 To understand the impact that the continued evolution of microdisplay technology will have on the performance and price of projection displays, the competing technologies will first be compared and evaluated in conjunction with the performance of other critical components of a projection system. Next, the market requirements for displays in each market segment will be compared. In the final section, a forecast for the growth of microdisplay based projectors will be developed

We describe a single panel SXGA projection display based on active matrix ferroelectric liquid crystal (FLC) technology. The FLC light-modulating layer is placed on top of a reflective CMOS backplane. This geometry effectively takes advantage of the fast switching sped and high resolution possible in a submicron thick layer of FLC and fine design rules available in standard CMOS fabs. The fast FLC switching speed allows both gray scale and color to be generated with time sequential addressing. Current FLC materials are well suited to operation with mainstream 5 volt CMOS processes and offer a clear path to compatibility with newer 3.3 and 2.5 V processes. These lower voltages result in lower power consumption and finer design rules allowing for higher density of on-chip electronics such as MPEG2. The reflective quarter wave plate design of the display affords a large angular acceptance resulting in flexibility of optical design as well as excellent contrast and throughput vs. viewing angle. We describe this color projection display and the high temperature FLC materials and mixtures optimized for them.

The response of a nematic liquid-crystal reflective device is computed using the Berreman codes incorporated in the NASA ViDEOS software. The results are applied to a color- sequential projection system, and show the throughput limitations imposed by the nematic response time. The temperature dependence of nematic viscosity is included, to demonstrate the increase in response speed at projector operating temperatures.

In this particular 'affair' the participants are less than human but have individual personalities they bring to their relationship with each other. High pressure metal halide lamps such as BriteArc lamps have the highest luminance and radiance of all continuously operating practical light source. Since these lamps have short arcs and are available in power ratings from about 30W to 30kW they have found applications with various optical systems. Besides the lamps, such systems include an electrical control device and an optical system. To fulfil the user's requirements for a specific application, it is not only important to choose the right lamp, but crucial to achieve a harmonious marriage between the light source, electrical control device and the optics. To run a high pressure discharge lamp an ignitor/ballast system is essential This stabilizes the lamp parameters. The chemical components inside the lamp determine the lamp voltage and the gear determines, via the current, the lamp power. These are directly related in the luminance and color temperature of the emitted light. Therefore lamp performance and effective life are dependent on the ignitor, control gear and lamp combination. Since the lamp emits radiation in all directions, collection of the light from a lamp can be improved by using reflectors to deliver the light into a lens system. Since lamps with short arc gaps approach a point source they appear ideal for optical system applications. The shape of the reflector and the focusing of the lamp determine which part of the light is collected out of the light-arc. In the case of an LCD projector, the final light output also depends on the transmission characteristics of the LCD panels. Their nonlinearity causes the color of the emitted light to be different from the lamp color. All these parameters have to be optimized to obtain the highest performance. This leads to the conclusion that a carefully matched combination of lamp, ignitor/ballast and optics should guarantee the best system performance. This paper sets out to provide some guidelines on attempting to achieve a harmonious relationship between the three partners in this particular eternal triangle.

Compact LCD projectors require a high efficiency light source that has the smallest possible spatial extent. Further, they require optical systems that preserve the etendue. Current projector illumination systems have aberrations that produce a light beam whose etendue far exceeds the intrinsic etendue of the light source itself. As a result both efficiency and uniformity fall short of what is theoretically possible. We provide a theoretical framework for understanding these aberrations and the magnitude of their effect. We also present results showing the efficiency, uniformity, and other performance gains which are possible when these aberrations are corrected. This work also describes the performance of long-life, short-arc metal halide lighting systems that are able to increase screen brightness of compact projectors several fold without any increase in system power or heat. With these systems it has been possible to design and validate lamps operating at 50 Watts, producing > 3,000 lumens and having excellent lumen maintenance throughout their 4,000 hour life. The benefits of the combination of an improved etendue-preserving optical system and a short-arc metal halide lamp will be demonstrated.

An optical engine for LCD projection display, to be used in normal lighting has been developed. This system has full color, compact size and good brightness. A metal halide lamp with 1.6 mm arc length and 270 watts was used as light source. The system has been accurately simulated by using ray tracing. In addition to the good color performance, excellent uniformity within 90 percent across the screen was achieved.

Several illumination calculation programs are available o aid in the design of electronic projectors. In this paper, two programs are compared: ASAP and TracePro. First, their capabilities are compared in a checklist. ASAP has enough features to model almost any optical system, while TracePro is a newcomer that is in the process of adding necessary features. TracePro excels at system entry and file transfer. Second, each of them is used to analyze tow electronic projector models: and early design wi a single 6.4 inch diagonal panel and a current design with three 1.3 inch polysilicon panels. Performance predictions by the two programs are similar, although ASAP traces rays much faster.

Digital processing of video signals can introduce many types of artifacts visible at the final display. One artifact, called luminance contouring, occurs when the number of bits that is output from the final digital processing stage is small enough for the luminance step corresponding to one bit to be visible at the display. While luminance contouring is rarely a problem in CRT displays, it is known to occur in digital micromirror device (DMD), plasma and liquid crystal device (LCD) displays. This paper provides a method to determine if luminance contouring is likely to occur in a given display when driven by a given bit count. Also indicated are the luminance and drive levels where luminance contouring is most likely to occur in common display types, including the DMD, twisted-nematic LCD and CRT displays.

With the new light valve technologies and availability of international broad-band communication channels high-end large screen TV projection is a highly growing contribution to the multi-media world of today. The exciting story already started 58 years ago with the invention of the EIDOPHOR diffractive oil light modulator. The long way to turn electronic cinema into a reality triggered novel applications, e.g. teleconferencing and real time surgery transmissions at universities. Several technical approaches of spatial light modulation were tried, and finally several different solutions are feasible to provide video projectors, meeting the requirements of the different display applications of today and tomorrow. The technical history is reviewed and the limitations and feasibilities of new technologies are presented in respect to existing and new applications.

A high efficiency, narrow spectral linewidth lasing pixel device that implements a low-voltage spatially patterned variable loss element placed inside an optically pumped high-gain laser cavity is experimentally studied. The output properties of this system make it potentially useful for digital projection displays. Coupling and grey-scale control of an intracavity pixelated laser projected system is studied experimentally and by numerical simulation. Results indicate that pixel independence can be maintained in high Fresnel number resonators.

Two kinds of LCD light valves are presently used in LCD projectors: HT poly valves, with an aperture higher than 50 percent, but with limited size due to a specific high cost of the technology, and amorphous silicon valves with a much more attractive dollar per square inch figure, but with much higher sizes due to a limited resolution capability. We have broken this a-Si:H valve resolution limit by developing high performance short channel length BCE TFTs, high aperture pixels with black matrix underneath the TFT array and ITO pixels on the top, placed spacers to optimize uniformity and shield the TFT against light, high tilt polyimide/liquid crystal combination, and integrated drivers made of the same amorphous silicon TFTs. We will present our solutions, which can be implemented in any a-Si:H production line, with emphasis on those related to the integration of drivers. Driver integration with a-Si:H TFTs can be achieved without any compromise on performance nor on reliability, and we will report on actual life times above 10 khrs for valves operating under high thermal stress. As a result we have opened the door to a new and broad a-Si:H valve family providing optimized performance and cost figures for sizes between 1 and 6 inches in diagonal.

The optical design of projection zoom lens by using special surfaces, such as aspherical surface and grin lens are presented in this paper. The techniques to approach the special design from all-spherical design are described. The results show that the use of grin lens and glass modeling asphere can effectively reduce the element number and the image quality is kept meanwhile.

Surface plasmon tunable filter (SPTF) is a new technology under development at Jet Propulsion Lab. when applying to LCD projects, SPTF can simplify the system structure, and enhance the efficiency. A scrolling SPTF which consists three SPTFs can generate scrolling red, green and blue colors, is able to enhance the efficiency of a single panel LCD projector up to the same level as a three panel LCD projector. A scrolling SPTF which consists six SPTFs and can generate two set of scrolling RGB colors, will enable a single panel LCD projector to be 100 percent more efficiency than the current three panel LCD projector.

Several methods providing phase-only spatial light modulation will be compared based on the rate of photon efficiency that can be theoretically achieved. Three basic phase modulation schemes are considered in the paper: tilt- type, grating-type and piston-type. The comparison also includes ways of converting phase modulation into observable intensity variations.

Advances in communications technology are now supporting images that match the visual capabilities of the user. Specifically, images in the range of 3,000 X 2,000, 4,000 X 3,000 and 5,000 X 4,000 pixels will be available. These roughly correspond to single pages at 300 dpi usable windows displays at 300 dpi and windows graphics stations with no 'jaggies' at 600 dpi. Supporting video drivers for these displays are not available. The images can be supported by multiplexing individual ow cost image generators through high resolution light valves. This is Multiple Image Amplifier Technology. Basic needs, advantages and components are outlined.

We have developed the direct-drive image light amplifier (D- ILA), a reflective mode liquid crystal device for multimedia projection systems. Utilizing a single crystal silicon based reflective LCD with a homeotropic liquid crystal alignment, the D-ILA device produces bright, high resolution and high- contrast images from a small diagonal display area.

A new projection system using three IBM 1.3 inch diagonal reflective light valve panels will be described. The 1280 X 1024 pixel reflective panels achieve a high aperture ratio of greater than 90 percent, and have a very fast response time to support high quality video images. The light engine uses plate dichroic mirrors to split the white light into red green and blue channels, an X-cube color combiner is used to recombine the images into a single projection lens. A polarizing beam splitting cube is used for each channel to direct polarized light onto the panels and to act as analyzers for the polarized output. The system, which uses a 500 watt Xenon lamp, will produce more than 3 times the ANSI lumens of most CRT projectors. This lamp is also dimmable allowing the user to match brightness levels in multiple screen applications, while maintaining color temperature. Key performance characteristics will be discussed and a light budget of system losses will be presented.

A 200 inches large-area laser projection display is presented. the laser light processor is mainly composed of a white laser for light source, acousto-optic modulators and the laser beam scanner composed of a galvanometer and a polygon scan mirror. The white light source is a Krypton- Argon laser with main wavelengths 647nm, 515nm, 488nm, respectively. Collimated and focused laser beams are modulated at acousto-optic modulators according to the video signals. Dichroic mirrors are used for separating the white laser beam to red, green, blue light beams and recombining the modulated red, green, blue light beams to one light beam. Recombined laser beam is vertically scanned by a galvanometer running at 60Hz rate and horizontally scanned by the 24 facet polygon scan mirror rotating at the speed of 39,375rpm. Between the polygon scan mirror and the galvanometer, relay lenses are inserted for which horizontally scanned beam is focused onto the galvanometer mirror facet. The size of 4m X 3m image with high resolution is obtained at the throw distance of 7m using 4W white light.

Single-domain nematic liquid crystal (LC) devices based on either the polarization-rotation or the birefringent effect or both have been investigated for reflective spatial light modulators (SLMs) which use a polarized beam splitter to separate the input light beam from its orthogonal output beam. We have evaluated each LC mode in terms of its contrast ratio, brightness, operating voltage, and its tolerance in cell-gap non-uniformity. We have studied the hybrid-aligned, the 0 degree, 45 degrees, and 63.6 degrees twist nematic LC modes which can be operated in either normally-white (NW) or normally-black (NB). We have also investigated the mixed twist nematic (MTN) and self- compensated twist nematic for NW and tilted homeotropic mode for NB. 2D simulations have also been carried out for one of the NB modes implemented inactive-matrix-driven reflective SLMs to elucidate the effect of fringe-field which tends to reduce mainly the brightness for the NB modes and contrast ratio for the NW modes. The locations of the disclination lines depend on the driving method and display pattern. To improve the brightness, we have also studied polarization- independent LC phase gratings using patterned alignment for reflective SLMs. The basic equations for the diffracted and non-diffracted intensities for both the reverse-twist and orthogonal-twist two-domain LC phase gratings have been derived. The device parameters, the operating voltage, and the optical diffraction efficiency are given for various cases with a twist angle equal to or less than 90 degrees.

Previously, the author has described a new 3D imaging technology entitled 'real depth' with several different configurations and methods of implantation. Included were several methods to 'float' images in free space. Viewers can pass their hands through the image or appear to hold it in their hands. Most implementations provide an angle of view of approximately 45 degrees. The technology produces images at different depths from any display, such as CRT and LCD, for television, computer, projection, and other formats. Unlike stereoscopic 3D imaging, no glasses, headgear or other viewing aids are used. In addition to providing traditional depth cues, such as perspective and background images occlusion, the technology also provides both horizontal and vertical binocular parallax producing visual accommodation and convergence which coincide. Consequently, viewing these images do not produce headaches, fatigue, or eyestrain, regardless of how long they are viewed. A method was also proposed to provide a floating image display system with a wide angle of view. Implementation of this design proved problematic, producing various image distortions. In this paper the author discloses new methods to produce aerial images with a wide angel of view and improved image quality.

A 3D volumetric display utilizes the moving screen projection technique with a fast switching spatial light modulator is presented. This technique displays volumetric 3D images by successive projection of whole frames of 2D images, through an optical-mechanical image delivery system, onto a revolving translucent screen. The series of projected 2D images distributed in the space forms a volumetric image because of the after-image effect of human eyes. A ferroelectric liquid crystal spatial light modulator is used as the image source, which enables 256 X 256 X 128 monochrome voxels in the display space. A rotating- reflectors mechanism is used to perform the moving projection function. Methods of processing 3D data and sequencing frame data are developed to integrate the SLM system and the optical-mechanical mechanism.

The 3D volumetric display system allows true 3D visualization of computer generated images. The three color beam from the system's lasers are guided by the acousto- optic deflectors to a display medium. The display medium allows the laser beam to create discrete visible dots of light, called 'voxels', at any point within its imaging volume. Arrays of voxels are used to create images that are perceived by an observer from a perspective relative to his position. The volumetric display system is comprised of three major subsystems: (1) a laser optics system; (2) a computer-based controller; and (3) a helical display assembly. The laser optics system creates, modulates and projects laser beams onto the display medium. The computer- based controller processes instructions and other data and generates the electronics modulation and deflection signals that control the laser scanner and convert the beam into imaging pulses. The helical display is a volumetric medium that used simple optical and mechanical principles to transform the scanner laser pulses into visible 3D images.

An improved generation of our 'FELIX 3D Display' is presented. This system is compact, light, modular and easy to transport. The created volumetric images consist of many voxels, which are generated in a half-sphere display volume. In that way a spatial object can be displayed occupying a physical space with height, width and depth. The new FELIX generation uses a screen rotating with 20 revolutions per second. This target screen is mounted by an easy to change mechanism making it possible to use appropriate screens for the specific purpose of the display. An acousto-optic deflection unit with an integrated small diode pumped laser draws the images on the spinning screen. Images can consist of up to 10,000 voxels at a refresh rate of 20 Hz. Currently two different hardware systems are investigated. The first one is based on a standard PCMCIA digital/analog converter card as an interface and is controlled by a notebook. The developed software is provided with a graphical user interface enabling several animation features. The second, new prototype is designed to display images created by standard CAD applications. It includes the development of a new high speed hardware interface suitable for state-of-the- art fast and high resolution scanning devices, which require high data rates. A true 3D volume display as described will complement the broad range of 3D visualization tools, such as volume rendering packages, stereoscopic and virtual reality techniques, which have become widely available in recent years. Potential applications for the FELIX 3D display include imaging in the field so fair traffic control, medical imaging, computer aided design, science as well as entertainment.

This paper describes a fast algorithm of the face detection for an autostereoscopic display system allowing the viewing zone to follow the observer's head. This two phases face detection algorithm may real time detect the observer's eye- position such that the observers do not need to wear any artificial instruments to enable a most natural tracing 3D display system. The two phases face detection algorithm correlates the input image and an eigenface first, then send this correlated result through two thresholdings, and a filter to generate a possible face region. Then, the combination of the possible face region and the correlated result generates the face position information. Clustered background and eye-glasses wearing is allowed. This algorithm is also relatively robust on scaling and viewing angle variations.

Floating Images, Inc. is developing a new type of volumetric monitor capable of producing a high-density set of points in 3D space. Since the points of light actually exist in space, the resulting image can be viewed with continuous parallax, both vertically and horizontally, with no headache or eyestrain. These 'real' points in space are always viewed with a perfect match between accommodation and convergence. All scanned points appear to the viewer simultaneously, making this display especially suitable for CAD, medical imaging, air-traffic control, and various military applications. This system has the potential to display imagery so accurately that a ruler could be placed within the aerial image to provide precise measurement in any direction. A special virtual imaging arrangement allows the user to superimpose 3D images on a solid object, making the object look transparent. This is particularly useful for minimally invasive surgery in which the internal structure of a patient is visible to a surgeon in 3D. Surgical procedures can be carried out through the smallest possible hole while the surgeon watches the procedure from outside the body as if the patient were transparent. Unlike other attempts to produce volumetric imaging, this system uses no massive rotating screen or any screen at all, eliminating down time due to breakage and possible danger due to potential mechanical failure. Additionally, it is also capable of displaying very large images.

Thin-film nanotube carbon structuresexhibitgood emission properties. Thusthey are employed, as a base, for creating matrix field emitter arrays, flat displays and electrovacuum's devices. To design these devices one needs, however, to take into account emission current, electrostatic field, and intensity distribution over nanotube surface. An error in the emission current calculation is defmed by the error in calculating the electrostatic potential. We have numerically calculated the electrostatic field and the potential distribution by a three-dimensional model of the nanotube structure with the use of the fmite elements method and a special technique. The enor of the method was estimated to be 9% by solving the model problems. An anode cunent of 0.1 mA was generated for thin-film nanotube structures with a height of 10 nm and a diameter of 3 nm at potentials at the cathode of 0 V and at the anode of I kV for a cathode -anode spacing of 20 mkm. The calculated intensity on the emitter tip was 4000 ky/cm. Keywords: field emitter arrays, carbon nanotube, singular points, three-dimensional model Experimental investigation has demonstrated thin carbon films containing tube-like nanoclasters (tubellenes) to be a good field emission material1 . Presently, they are used as a base to develop field emission anays for displays and devices of vacuum microelectronic. Designing the devices involving these field emiUer arrays necessitates calculation electric field strength and emission current from the carbon film. The complex structure of the tubellene film surface prevents the application of analytical methods for the calculation. An error with calculating the emission current is defmed by the enor in calculation of electrostatic potential. The error of a few percents made while calculating the strength can result in a very large error in the field emission current estimation. In this paper we propose a numerical calculation of electric field and potential distribution over the emitter surface with the use of a three-dimensional model of nanotube clusters and the finite element method. Due to the singular field behavior near the emitter tip an accurate calculation of the field strength is hindered. A special technique has been developed to overcome this difficulty.

A forward model of an LC projector is studied to predict its colorimetric attribution. To identify color characteristics of the projector, 729 colors were measured in a dark room. The forward model was built using three methods: (1) a 3 X 11 multiple-polynomial regression matrix, (2) 3D look- up table (LUT) with cubic interpolation, and (3) a 1D LUT with linear interpolation. In addition, 216 colors were also measured to evaluate the prediction accuracy of the forward model. All methods can be used to obtain acceptable predictions of colorimetric attributions on the lC projector. When the 3 X 11 multiple-polynomial regression matrix was used, the average and maximum prediction differences were 2.18 and 6.68 (Delta) E_uv respectively. For the 3D LUT method, those values were 3.3 and 16.4 (Delta) E_uv, respectively. The results of the 1D LUT are comparable with those of the 3D LUT if the sampling points per channel of these two approaches are the same. If the sampling points per channel are dense enough, for example 16 points per channel, the performance of the 1D LUT is better than that of the 3 X 11 multiple-polynomial regression matrix.

Optical thin film color splitting and combining components for 3 panel projection display were designed using TiO₂ and SiO₂ as high and low refractive index materials, respectively, and fabricated by reactive electron-beam deposition at a substrate temperature of 300 degrees C. The resulting coating performances on the brightness and color performance were analyzed by chroma meter. The correlations between these results and their spectral curves measured by spectrophotometer were discussed.

Two types of 3D displays producing a volume image in a large hall are considered. The image is consisting of a set of horizontal or vertical scene slices. It is suggested for a slice scanning in vertical direction or along the depth to use a little light deflectors mounted in an observer glasses. That decreases significantly the requirements to 3D monitor elements. Two deflectors for this private optic frame scanning are considered: one based on a scanning galvanometer and other is a rotating disk on the bases of Fresnel prisms. The output images of these deflectors do not depend on a glasses orientation in the horizontal surface and therefore the observers may move free in the hall. This is an advantage of the suggested method as compared with the stereo methods.

A patent has been awarded for a new CRT design that eliminates the internal shadow mask, and promises a bright, rugged, high-resolution/large-format, multiscan/multi-sync display with potentially low manufacturing costs. The design incorporates a light-valve within the CRT. Modulation of the electron gun and the function of the shadow mask are replaced by two chemical reactions typical of phosphors: decays stimulation and quenching. These reactions are controlled through illumination of the phosphors by non- visible light projected through the light-valve. The image is generated in traditional raster form, but with a single, non-modulated electron gun; control of each pixel is made through modulation of the light-valve. The design decrease manufacturing alignment requirements and eliminates the need to focus the electron gun. Advantages include: high-G resistance due to elimination of the shadow mask; brighter displays because the electron beam is not occluded or absorbed by the shadow mask; elimination of decay rate as a parameter in phosphor choice and frame rate; and digital interfacing to image sources. Applications include: large- format displays without the physical constraints of the shadow mask and by elimination of distortion control requirements of the electron beam at the image edges; variable frame rates by modulating the decay rate of the phosphors through quenching; and stereoscopic displays without crosstalk through control of left-right phosphor decay rates.