Abstract: The invention relates to a photorefractive device made of single crystal of which the chemical composition substantially is Ba.sub.1-x Sr.sub.x TiO.sub.3 (0.01<x<0.1 BST) The method for manufacturing said device comprises: growing BST single crystal by Czochralski technique; annealing said crystal in oxidizing atmosphere; machining said crystal into cuboid with polished surfaces; poling said cuboid mechanically and electrically into single-domain state. Said device may ba a piece of said single-domain crystal, or an optoelectronic assembly including at least one of said crystal as the core part. Performances of said device are similar to the one made of BaTiO.sub.3. A reflectivity as high as 52% has been reached using said device as a self-pumped phase conjugator. Compared to BaTiO.sub.

Abstract: The present invention relates to a novel spatial light modulator comprising a plurality of individual pixels that each contain separate detectors, electronic circuitry, and optical modulators. A primary application of such a spatial light modulator is to provide the requisite nonlinear relationship between a plurality of optical beams fanned in to each detector on the one hand, and a plurality of optical beams fanned out from such modulator on the other, on a pixel-by-pixel basis. In one embodiment, the spatial light modulator is configured to differentially amplify the inputs to two separate detectors within each pixel, and to transform iORIGIN OF INVENTIONThe U.S. Government has certain rights in this invention pursuant to Contract No. F49620-87-C0007, awarded by the Department of the Air Force, and to Grant No. AFOSR-89-0466, awarded by the Defense Advanced Research Projects Agency through the Department of the Air Force.

Abstract: In a raster output scanner, a system for using one original beam and one facet of a rotating polygon to generate two consecutive scan lines. The original beam is first separated into two beams in a beam splitter. The resultant beams are polarized ninety degrees apart, and directed to the modulator. The beams are a sufficient distance apart so that the A/O modulator can modulate each beam with a minimum of crosstalk. The output beams are then brought together to within one scan line separation by a beam recombiner, which is a reversed beam splitter. The beams can be brought together to this close proximity without optical interference because the beams are plarized ninety degrees apart.

Abstract: In a raster output scanner, a system for using one original beam and one facet of a rotating polygon to generate a scan line which can be turned on to have three levels of intensity. The original beam is first separated into two beams in a beam splitter. The resultant beams are polarized ninety degrees apart, and directed to the modulator. The beams are a sufficient distance apart so that the A/O modulator can modulate each beam with a minimum of crosstalk. The output beams are then brought together and combined into one beam without optical interference because the beams are polarized ninety degrees apart. The beam can have several levels of intensity and be used to create several levels of gray scale at the output.

Abstract: A method and device for driving an electro-optical light shutter array including a plurality of shutter elements each having an electro-optical effect to polarize an incident light by setting up an electric field. The device includes a plurality of individual electrodes provided on the respective shutter elements and a common electrode provided on the respective shutter elements electrically in common. A square pulse is applied to the arbitrary individual electrode while a triangular pulse is applied to the common electrode to set up an electric field of which an intensity continuously varies within one driving period. Moreover, an alternating electric field may be set up in the electro-optical light shutter array in a recovery period. In this case, a first light amount when the positive electric field is set up and a second light amount when the negative electric field is set up are detected.

Abstract: A differential amplifier for gigahertz bandwidth electrical signals using fiber optics and integrated optical devices has a differential gain which is a function of the electrical to optical and optical to electrical conversion factors. The common mode rejection ratio of the differential amplifier at 1 GHz was greater than 30 dB and the common mode rejection ratio depended on the time difference between the differential amplifier inputs. A differential amplifier fabricated in accordance with this inventive concept could be used as an integrated module in radar and communications systems.

Abstract: A method of minimizing voltage induced drift in electro-optic devices, the optical state of which is controllable by the application of an electrical potential between first and second electrodes of the device, the method comprising controlling the electrical potentials applied to the first and second electrodes such that in use the average potential difference between the first and second electrodes is substantially zero.

Abstract: A laser sensor protector is provided comprising a nonlinear dynamic device which has a flat broad band reflectance covering the entire visible range in the on-state and allows for good optical quality and high transmittance (80-90) in the off-state. The device can be constructed using electro-optic materials or nonlinear optical materials. If electro-optical materials, i.e., those for which the refractive index can be controlled by an external field, or nonlinear optical materials, i.e, those for which the refractive index can be controlled by the light intensity, are used to construct the present invention, it is possible to achieve dynamic switching, that is, the device is clear in the off-state and it is highly reflective over a broad band in the on-state.

Abstract: A device for modulating light, wherein a layer of material having a superconducting state is placed in the optical path of a light source and is switched between transparent, non-superconducting and non-transparent, superconducting states by a modulation circuit, thereby providing optical data modulation. A cooling device is provided to maintain the layer of material in its superconducting state. The light source is maintained at a constant optical output which reduces spectral dispersion.

Abstract: A device for controlling transmittance of light therethrough includes first and second transparent substrates which are spaced from each other. The first substrate has at an end portion thereof a notch. First and second transparent electrode layers are respectively coated on inner surfaces of the first and second substrates for defining a space therebetween. The first layer is partially cut off so as to conform to a periphery of said notch. An electro-optically responsive material substantially fills up the space. The material is made so as to allow transmittance of light therethrough to change in response to voltages applied between the first and second layers. A terminal is received in said notch and said space, and is sized so as to be biased against the first substrate and the second layer so as to ensure an electrical contact between the terminal and the second layer.

Abstract: An optical article capable of modulating the reflection of polarized monochromatic electromagnetic radiation is disclosed comprised of a reflective metal layer, means acting as a support for directing the electromagnetic radiation to the reflective metal layer, an electrooptic medium that exhibits a refractive index which is a function of an applied electrical potential, and a counter electrode. At least one of the reflective metal layer and the counter electrode taking the form of laterally spaced segments. The reflective metal layer has a thickness of less than 0.5 .mu.m, and a dielectric layer having a thickness in the range of from 0.1 to 10 times the wavelength of the electromagnetic radiation and comprised of at least one metal oxide, metal fluoride, or low molecular weight aromatic compound is coated on the support. The electrooptic medium is a polymeric layer coated on the reflective metal layer exhibiting a second order polarization susceptibility greater than 10.sup.

Abstract: A light signal generating device having a plurality of electro-optical light shutter elements which are turned on and off individually in accordance with image data. The light shutter elements are connected to individual electrodes each, and also connected to a common electrode. The common electrode and a power source for supplying a voltage to the individual electrodes are connected with a grounding line. Discharge lines are disposed between the common electrode and the grounding line, and switching elements are disposed on the discharge lines so as to prevent discharge currents, which are drawn from the light shutter elements at falls of the driving voltage, from flowing into the grounding line.

Abstract: Method and apparatus for electro-optically modulating the intensity of an incident light beam including a coupling prism with a high reflective index, a semiconductor substrate in optical contact with the coupling prism and having a conductive area formed therein, an organic electro-optic film formed on the substrate and covering at least a portion of the conductive area, and a transmission line disposed above the electro-optic film and cooperating with the conductive area to form electrodes for use in applying an electric field across the electro-optic film. Light directed through the substrate by the coupling prism couples with surface plasmons at the film-to-metal interface and is selectively reflected or absorbed depending upon whether or not an electric field is applied.

Abstract: The TIR modulator has an electrode array distributed across an area of the reflecting surface of the electro-optic material. The electrode array has interdigitated electrodes extending inward from a rectangular-shaped outer electrode conducting block and outward from a diamond-shaped inner electrode conducting block. A diamond-shaped area with no electrodes is preferably symmetrically within the inner electrode conducting block of the electrode array on the reflecting surface. The uniform voltage difference between the electrodes and the varying lengths of the electrodes creates a fringe electrical field in the electro-optical material and an optical phase grating to diffract the incident light on the reflecting surface. The zero order nondiffracted light becomes the output beam. The optical phase grating will control the incident beam's optical profile at the modulator (near field) and hence the imaged spot size at a focus at the image plane (far field).

Abstract: The specification discloses a method for reducing current leakage and enhancing UV stability by using electrochemichromic solutions whose solvents include, either solely or in combination with other solvents, glutaronitrile (GNT).

Abstract: The specification discloses electrochemichromic solutions and devices based on the use of from about 5% by volume of a nonpolymeric material having a high volume resistivity and high dielectric constant to reduce leakage current without unduly increasing solution viscosity. In an alternative aspect, high quantities of such materials are used even though solution viscosity increases to the point of preventing room temperature vacuum backfilling in order to take advantage of other features of such solutions.

Abstract: A method of and a device for driving a light shutter having an electrooptical effect to polarize an incident light by applying an electric field to the light shutter. When the light shutter is made activate, an excessive electric field in addition to a half-wave electric field which is a specific one to polarize an incident light at 90.degree. in the static characteristics of the light shutter is applied to the light shutter initially, and subsequently, the half-wave electric field only is applied to the light shutter. To discharge the electric charge accumulated in the light shutter, no voltage is applied to electrodes each of which is provided on the wall of the light shutter so as to oppose each other subsequent to the application of the electric field until the next application thereof.

Abstract: An optical intensity modulator includes a compound semiconductor substrate of a first conductivity type having first and second surfaces, and a compound semiconductor active layer of the first conductivity type formed on the first surface of the compound semiconductor substrate. An incident laser beam to be intensity-modulated is applied to the compound semiconductor active layer. The modulator further includes a compound semiconductor layer of the first conductivity type formed on the compound semiconductor active layer, an opposite conductivity type compound semiconductor layer of a second conductivity type opposite to the first conductivity type, a first electrode formed on the opposite conductivity type compound semiconductor layer, and a second electrode formed on the second surface of the compound semiconductor substrate.

Abstract: A carrier light beam transmitted through a light valve is modulated to convey information along a communications system. The modulation factor, baud rate and efficiency of the light valve can be increased by directing a modulated light beam a number of times through the valve.

Abstract: There is disclosed a light energy management system for use in conjunction with, in one embodiment, the exposure unit of a xerographic reproduction system. The light management system serves to funnel the unmodulated light for proper impact on a modulating device and to maintain the dark effect of the device when in the unmodulated mode. Light baffles are used for this purpose, some of which are formed as a series of angular steps designed to eliminate unwanted light along the longitudinal axis of the modulated light path. The angular step, in one embodiment, takes the shape of a semi-circular bee thorax. The modulated light path includes a light focus lens and a pair of mirrors for sending the modulated light pulses to the reproduction process surface.

Abstract: A self-referencing target imaging system 10 capable of long range imaging at visible wavelengths is disclosed herein. The imaging system 10 of the present invention includes a transmitter 20 for illuminating a target 30 with a series of electromagnetic pulses P. The present invention further includes an apparatus 35, 40 and 45 for redirecting first R1 and second R2 reflections of each illuminating pulse P from first 32 and second 34 portions of the target 30, respectively. A frequency modulator 50 driven by a generator 55 shifts the frequency of each first reflection R1 to produce a reference reflection R1' corresponding to each illuminating pulse P. The present invention further includes an arrangement of reflective elements 60 and 65 for respectively combining the reference R1' and the second R2 reflections of each illuminating pulse P to generate a series of combined reflections. A detector 70 generates an imaging signal in response to the series of respectively combined reflections.

Abstract: A spatial light modulating element including an electrooptic and photoconductive single crystal plate, a light-transmitting insulating layer provided on at least one of opposite surfaces of the electrooptic and photoconductive single crystal plate, and a pair of electrodes provided for applying an electric field to the insulating layer and the single crystal plate. The insulating layer is formed from a uniaxial single oxide crystal which is crystallographically oriented such that the insulating layer exhibits neither birefringence, nor an electrooptic effect in a direction of the electric field. The insulating layer may be a LiNbO.sub.3, LiTaO.sub.3 or TiO.sub.2 (rutile) single crystal plate cut normal to the (001)-axis.

Abstract: An optical unit having an electrooptical element whose optical properties are changed as a function of a voltage applied thereto to modulate an incident light in response to the applied voltage. The optical unit includes a shielding member for electrically shielding at least a portion thereof which includes the electrooptical element from an external electric field. The shielding member protects the electrooptical element from an influence of an external electric field on an electrooptical effect of the electrooptical element. The shielding member may be an electrically conductive member, such as a metallic casing accommodating the electrooptical element, or an electrically conductive layer covering a housing accommodating the element.

Abstract: An optical light beam position control system utilizes Kerr cells and Lummer-Gehrcke plates to produce sets of optical phased linear arrays for beam positioning and beam monitoring. The system controls a light beam in the vertical and horizontal axes by the means of two optical phased linear array generators with associated monitoring and positioning optics.

Abstract: An electro-optic light modulator of the type including a body of an electro-optic material having opposed surfaces and a pair of planar conductive electrodes on at least one of the surfaces of the body. Polarity-reversing drive circuitry applies a voltage across the electrodes, the polarity of the voltage being reversed at a frequency of about 1 Hz or less with polarity reversal occurring either when the light modulator is turned off or when there is an insignificiant voltage drop across the electrodes. This low frequency of the reversal of the polarity of the voltage substantially eliminates drift of the voltage-transmissivity of the modulator, lowers leakage, and reduces damage to the electrodes during a given period of time of operation.

Abstract: An electro-optic cell linear array, such cells being commonly referred to as PLZT cells or Kerr cells, for use in an electro-optic imager wherein the electrode lines are placed at from 15.degree. to 75.degree. relative to the centerline of the array. The advantages of such a configuration are that the electrode lines are not imaged and that adjacent cells have overlapping areas of exposure.

Abstract: 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.

Abstract: An infra red radiation modulator comprises a p type silicon substrate 1 having spaced n type and p type doped regions 2, 3 having respective doping concentrations of approximately 10.sup.20 and 10.sup.16 /cm.sup.3. A signal source 11 provides a bias voltage between the doped regions 2,3 via electrodes 4 for modifying the concentration of free carriers in the substrate between the doped regions and therefore the response of the modulator to incident infra red radiation. By appropriate control of the bias voltage the modulator can be caused to modulate, chop, filter or spectrally scan the incident radiation.