Hughes Aircraft Company

Hughes Electronics Corporation

United States of America as Represented by the Secretary of the Air Force

The United States of America as Represented by the Secretary of

Uzi Efron

Paul O Braatz

Bernard H Soffer

Jan Grinberg

Michael J Little

Yuri Owechko

David M Pepper

Thomas R O'Meara

Murray S Welkowsky

Chiung-Sheng Wu

Roger H Brown

Clarence P Hoberg

Chungte W Chen

Emanuel Marom

Tsung-Yuan Hsu

Prahalad K Vasudev

Shin-Tson Wu

Joel N Schulman

Richard C Lind

Arthur N Chester

William R Byles

Norman W Goodwin

Wilbur P Brown, Jr

Robert N Schwartz

Larry Raymond Dalton

Wayne P Schoenmakers

Glenn D Robertson, Jr

Raymond Balcerak

Eli Wiener-Avnear

A head-mounted display device (10) offers light weight, a low center of gravity, and low moments of inertia about the azimuthal and elevational axes of head movement. The display device (10) employs an angulated beam splitter mirror (16) disposed between a user's (22) eye (20) and an inner combiner surface (18a) of a visor (28). A projector (36) is carried laterally of the user's eye with a low center of gravity and a position close to the horizontal axis of elevational movement of the head. This projector (36) includes an image source (12) and an compact light-weight relay optics module (14) along with a projection fold mirror (30) disposed at eye level and laterally of the beam splitter mirror (16) to project image light to the beam splitter mirror (16). The beam splitter mirror (16) reflects the light onto the inner surface (18a) of the combiner (18) for reflection back through the beam splitter mirror (16) and to the user's eye (20). Alternative embodiments provide for color correction, or for monochrome image projection at even lighter weight. An alternative embodiment provides for both color correction and a weight nearly as light as the monochrome version by use of diffractive lenses in the relay optics module.

Low-cost light-weight head-mounted virtual-image projection display with

An erasable optical memory is provided by an erasable bistable photoactive chromophore that is covalently bonded to a polymer microsphere. An azobenzene chromophore that is bonded to the microsphere by an oxygen or NH replacement of chlorine, or a CH double bond to N, is preferred. An array of such microspheres is encoded by applying radiation at a resonant wavelength to induce a conformational change in the chromophores for selected microspheres, and the encoded pattern is read out by detecting changes in either absorption or fluorescence.

Erasable optical memory and method

An infrared (IR) radiation transducer integrates an IR detector array with a liquid crystal (LC) readout. The IR detector is preferably a pixelized bolometer array, but other detectors such as pyroelectric materials are possible. To modulate the LC in response to detected IR radiation, a modulating section is provided that includes a charge injection structure which injects electrical charge in response to the detected IR radiation, and a charge transfer structure that transfers the injected charge to the LC readout section. During its active phase the charge transfer layer is depleted of majority charge carriers, and the charge injection and transfer mechanism operates in a manner analogous to a bipolar transistor. A visible readout is obtained by directing readout light through the LC, where it is modulated in accordance with the detected IR image. The transducers are small and light weight enough to be incorporated into a pair of goggles, for which no separate cooling is required.

Infrared transducer and goggles incorporating the same

A combined optical imaging/display device employs a liquid crystal light valve (LCLV) with a charge coupled device (CCD) input, and a photosensitive CCD or charge injection device (CID) array for receiving an input image and developing a corresponding signal pattern. The signal pattern is applied as an input to the CCD after amplifying it and manipulating it as desired. The CCD and photosensitive array are provided on a common substrate; their cells may be arranged in alternating rows or in separate arrays. The invention is applicable to active vision enhancement goggles.

Optical imaging/display CCD light valve and method

An eye protection device 10 comprising a liquid crystal light valve 20 for providing an image of a scene. The light valve images the field of view under observation in a spectral range which matches the human eye. It will automatically reject a laser threat by simply absorbing the energy therefrom in the photoconductive layer thereof. Thus, the invention 10 provides a broad spectrum, zero response time, angle and polarization independent, sensitive eye protection device having a fast recovery time, high extinction coefficient and a high damage threshold. Hence, the invention is expected to be of significant utility to personnel operating in hostile environments.

Liquid crystal light valve goggles for eye protection

A cascaded adaptive optics system for correction of aberrations in a light beam. The system includes a plurality of spatial light modulators (SLMs) in a cascaded arrangement to provide an adaptive optics system characterized by wide range, rapid response, and high resolution. The spatial light modulators may be identical or have characteristics that are complementary in providing a combined output that advantageously corrects for aberrations. A conventional adaptive optics system such as a deformable mirror may be used as one or more of the SLMKs. Liquid crystal light valves (LCLVs) may be advantageously used as one or more of the SLMs in the invention. A single LCLV may be cascaded with itself in a multiple-pass configuration by means of suitable reflectors.

Cascaded adaptive optics system

Apparatus for compensating for inherent distortions in a modified liquid crystal light valve used in an integrated wavefront sensing and wavefront control system for laser optics. A main wavefront sensing and control system utilizes a liquid crystal light valve selected for response speed but having inherent surface non-linearities. A beam from an auxiliary laser is intermittently applied, while the main laser is blocked, to both the fast response LCLV of the main system and to a slower response LCLV of an associated correction system. The second LCLV system corrects for the non-linearities in the surface of the first LCLV and then maintains the stored correction signal for a decay interval which corresponds to several response times of the main LCLV, thus permitting the main LCLV system to perform fast correction of atmospheric aberrations in the laser beam wavefront unaffected by inherent surface non-linearities.

Method for adaptive correction of the phase non-uniformity of a liquid

A single-Schottky liquid crystal is disclosed in which a series of Schottky contacts are made on one side of a photoconductor substrate by a metal matrix mirror, with a doped semiconductor back contact electrode on the other side of the substrate. The light valve offers several operational advantages over MOS devices, and is easier to fabricate than double-Schottky light valves. It can be operated either in an AC mode or, by doping the liquid crystal ions, in a DC mode.

Single-Schottky diode liquid crystal light valve and method

A liquid crystal light valve is provided with a microgrid of grooves in the photoconductor surface to divide the photoconductor into high resolution pixels. The liquid crystals fill the grooves to seal them and contribute to a potential barrier at the grooves that prevents lateral charge migration between pixels. In a metal oxide semiconductor (MOS) embodiment an oxide layer extends over the pixels and partially overhangs the grooves. A metal matrix mirror is formed over the insulative layer, and extends into a portion of the grooves to shield the underlying silicon from photoactivation while maintaining an electrical isolation between pixels.

Liquid crystal light valve with grooved microgrid and method of forming

An optical light valve system 10 for providing an amplified phase conjugated replica S.sub.1 * of a potentially low intensity phase aberrated optical signal beam S.sub.1 is disclosed herein. The optical light valve system 10 of the present invention includes a reference beam source 17 for providing a coherent reference beam R having first and second components of first and second polarization states, respectively. Further included is a signal beam source 15 for providing a coherent signal beam S of the first polarization state. An improved optical light valve 20 phase conjugates the second component of the reference beam in response to the aberrated beam S.sub.1 *.

Optical light valve system for providing phase conjugated beam of

A double Schottky diode light valve (5) includes a liquid crystal (80) for locally modulating a beam (120) by polarization rotation to produce a modulated beam (121), and a photoconductor (40) located adjacent the liquid crystal (80) for receiving and absorbing a second beam (110). The photoconductor (40) controls the polarization responsively to the optical content of the second beam (110). The photoconductor (46) includes a semiconductor substrate and a pair of Schottky diodes (60/40, 30/40) disposed on opposing sides of the substrate. The absorption of the second beam (110) by the substrate (40) produces photogenerated carriers. The pair of Schottky diodes (60/40, 30/40) maintain the substrate (40) substantially depleted of such carriers and also reflects the modulated beam back through the liquid crystal.

Double-Schottky diode liquid crystal light valve

A double Schottky diode light valve (5) includes a liquid crystal (80) for locally modulating a beam (120) by polarization rotation to produce a modulated beam (121), and a photoconductor (40) located adjacent the liquid crystal (80) for receiving and absorbing a second beam (110). The photoconductor (40) controls the polarization responsively to the optical content of the second beam (110). The photoconductor (46) includes a semiconductor substrate and a pair of Schottky diodes (60/40, 30/40) disposed on opposing sides of the substrate. The absorption of the second beam (110) by the substrate (40) produces photogenerated majority carriers. The pair of Schottky diodes (60/40, 30/40) maintain the substrate (40) substantially depleted of such carriers and also reflects the modulated beam back through the liquid crystal.

Double-schottky diode liquid crystal light valve

A near bandgap radiation modulation spatial light modulator (NBRM SLM) using multiple quantum wells (MQWs) is disclosed. Generally, the MQW NBRM SLM of the present invention comprises a MQW optical modulator and driver means for driving the MQW optical modulator. The MQW NBRM SLMs of the present invention can be configured in a plurality of configurations. The driver and MQW optical modulator may be configured in hybrid or monolithic configurations. The MQW optical modulator can be operated in either transverse or longitudinal electric field modes. The MQW NBRM SLM structures can be operated using either electroabsorption or electrorefraction effects, and in transmissive or reflective modes. The structures are operable with different addressing and write-in mechanisms, including photoactivation and electronic addressing. Alternate embodiments have special features such as cascaded heterojunction MQWs and pixelized submicron metal mirror. The disclosed invention provides an improved, high speed, high resolution, semiconductor driver-compatible, spatial light modulator using multiple quantum wells.

Near bandgap radiation modulation spatial light modulators

An LCLV is formed with a sapphire substrate base, a highly doped, thin silicon epitaxial layer forming an ohmic back contact on a smooth surface of the sapphire substrate, and a lightly doped, high resistivity silicon epitaxial layer in the range of about 20-60 microns thick on the back contact. The use of a sapphire substrate provides a better surface quality and higher resolution than previously available with the semiconductor substrates. Lattice defects in the thin back contact are reduced by the formation of a buried amorphous layer adjacent the sapphire substrate, and subsequent recrystallization thereof using the unamorphized portions of the back contact as recrystallization seeds. The application of the invention to both MOS and Schottky diode LCLVs is discussed.

Silicon-on-sapphire liquid crystal light valve and method

A pulsed readout technique is described for liquid crystal light valves which eliminates the problem of readout beam leakage through the light valve mirror. The readout beam is pulsed on only when the light valve's semiconductor layer is out of a depletion state. This can occur during an accumulation state or, in certain applications, during a specially inserted quiescent period in the light valve voltage cycle. The invention is applicable to light valves with various types of modulating inputs, and can be used with either dielectric or metal matrix mirrors.

Growing community of inventors

Los Angeles, CA, United States of America

Uzi Efron