Hughes Aircraft Company

Hughes Electronics Corporation

The United States of America As Represented by the Secretary of

Chiung-Sheng Wu

Jan Grinberg

Paul O Braatz

Uzi Efron

Shin-Tson Wu

Tsung-Yuan Hsu

Murray S Welkowsky

Anson Y Au

Khoon-Cheng Lim

Keyvan Sayyah

Larry Raymond Dalton

Raymond Balcerak

Eli Wiener-Avnear

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 imaging system that can tolerate high intensity optical beams without a reduction in the system's field-of-view, comprises an imager, a fiber array positioned at the image plane of the imager, a sensor array positioned at the output end of the fiber array, a panel display positioned in proximity of the fiber array and an image processor for electronically processing the information from the sensor array.

Laser-hardened eye protection goggles

The angular and/or spectral bandwidth of a holographic lens assembly can be widened to accomodate highly diverging and/or wide spectral bandwidth illumination sources, respectively. Each lens in the lens assembly is comprised of a plurality of angularly customized holograms (an angularly customized hologram set). Each of the individual holograms in an angularly customized hologram set has an acceptance angle range that is centered on a discrete peak acceptance angle. The separation between the holograms' peak acceptance angles is chosen so that the acceptance angle ranges of the individual holograms overlap. The resulting cumulative acceptance angle range of each angularly customized hologram set provides a holographic lens assembly that has a wider angular bandwidth than prior holographic lenses. The spectral bandwidth of the lens assembly can be similarly widened by adding a spectrally customized hologram set to the lens assembly in which the spectral waveband of each of the individual spectrally customized holograms partially overlap. Specific applications to various types of displays are disclosed, as well as preferred fabrication techniques for the holographic lenses.

Holographic lenses with wide angular and spectral bandwidths for use in

A liquid crystal light valve is provided with an array of photoconductive pedestals surrounded by a dielectric matrix material. Metal mirror pads are formed on top of each pedestal to form a high resolution metal matrix mirror, with each pedestal/mirror combination servicing one image pixel. The dielectric matrix forms a potential barrier between the individual photoconductive pedestals which prevents lateral charge migration between pedestals. The metal matrix mirror also shields the underlying photoconductive pedestal from photoactivation by the readout beam. The dielectric matrix material has a lower dielectric constant than the photoconductive pedestals, allowing the impedance of the photoconductive pedestals to match the impedance of the liquid crystal layer with a much thinner layer of photoconductive material than in prior LCLVs using a continuous photoconductive layer. The thinner photoconductive layer results in higher electric fields which improve the LCLV's response time, photodegradation rate, spatial resolution and spectral response.

LCLV having photoconductive pedestals each having a cross-sectional area

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 liquid crystal (LC) display method and apparatus applies respective active LC bias voltages to both a master LC cell, and a phase compensation LC cell for the master cell. The bias voltages are selected to reduce the response time of the master cell, and to establish a common multicolor dark state for that cell. With a proper selection of the bias voltages, the products of the liquid crystal thickness and birefringence for each cell are substantially equal and mutually cancel. A bias voltage is first established for one cell, and the bias voltage for the other cell is then scanned to locate the point of mutual cancellation. A range of different bias voltages are possible, and a suitable bias is selected to balance response time against the required operating voltage range. A multicolor display system using only a single light valve can be realized.

Liquid crystal display method and apparatus with tuneable phase

A light valve (10) includes a layer of a liquid crystal (16), a MOS substrate structure (18) with a dielectric layer (24) and a semiconductor layer (26), and an optically isolating mirror (14) between the liquid crystal layer (16) and the substrate structure (18). An external AC biasing voltage is applied across the MOS substrate (18) and the liquid crystal layer (16). The liquid crystal layer (16) is sufficiently thick that it operates in the surface birefringent mode with a high contrast ratio and a short response time to changes in the write-in light beam, when a sufficiently high biasing voltage V.sub.p is applied.

MOS light valve with nematic liquid crystal operating in the surface mode

An infrared (IR) simulator is disclosed in which an array of pixels is defined on an insulative substrate by resistor bridges which contact the substrate at spaced locations and are separated from the substrate, and thereby thermally insulated therefrom, between the contact locations. Semiconductor drive circuits on the substrate enable desired current flows through the resistor bridges in response to input control signals, thereby establishing the appropriate IR radiation from each of the pixels. The drive circuits and also at least some of the electrical lead lines are preferably located under the resistor bridges. A thermal reflector below each bridge shields the drive circuit and reflects radiation to enhance the IR output. The drive circuits employ sample and hold circuits which produce a substantially flicker-free operation, with the resistor bridges being impedance matched with their respective drive circuits. The resistor bridges may be formed by coating insulative base bridges with a resistive layer having the desired properties, and overcoating the resistive layers with a thermally emissive material. The array is preferably formed on a silicon-on-sapphire (SOS) wafer. Arrays of electromagnetic radiation bridge detectors may also be formed, with the bridges having either resistor, thermocouple or Schottky junction constructions.

Growing community of inventors

Los Angeles, CA, United States of America

Chiung-Sheng Wu