Abstract: An improved process is provided for making optical limiters having a graded axial distribution of a reverse saturable absorber compound, such as a buckminsterfullerene, in a host matrix, such as polymethyl methacrylate or polycarbonate. The process of the invention includes: (a) dissolving the reverse saturable absorber and the host matrix in a suitable solvent to form a solution having a preselected ratio of reverse saturable absorber to host matrix; (b) casting the solution onto a surface to form a film; (c) evaporating the solvent to form a free-standing film; (d) performing steps (a)-(c) for each different desired ratio of reverse saturable absorber to host matrix; (e) stacking the free-standing films in a desired order; and (f) hot-pressing the stack to form the optical limiter having a graded distribution of the reverse saturable absorber in the host matrix. If desired, the stack of films can be placed in a die for hot-pressing. The films can be pre-cut to the shape of the die.

Abstract: A structure consisting of two cover layers sandwiching a polymer and solvent layer is useful for making automatic light valves. Mechanical and optical properties are improved by a novel continuous network of bonds which transmit stresses from one cover layer, to and among the polymer chains, and then to the second cover layer. The laboratory and factory preparation methods necessitated by this layered and bonded structure are described. These automatic light valves may be used for making optical displays, processing information, and building apertures.

Abstract: A photochromic light control mirror comprises a photochromic substrate having a reflective film deposited at one side thereof. Alternatively, a mirror (i.e., a layer of glass having a reflective film deposited at one side thereof) is coated with a photochromic coating. An ultraviolet light source illuminates the photochromic material to change the reflectance of the mirror. The reflectance can be manually controlled whereby the intensity of the light source is controlled by adjusting the voltage driving the light source. Alternatively, the reflectance can be automatically controlled whereby the intensity of the light source is controlled by a photo detector which varies the voltage driving the light source in response to detected light.

Abstract: A transparent photochromic medium is placed before the film or film-equivalent of a camera or photographic imaging device such that a light exposure of the medium temporarily darkens it according to the different light values in the image. A subsequent exposure of the film is influenced by the intervening photochromic device so that the range of light is moderated, reducing over- and under-exposure of areas of the film.

Abstract: The present invention provides protection from lasers with a high nonlinear bsorption structure including a mirror which directs an incident beam to a beam splitter. A focusing lens receives and focuses the radiation to a higher intensity beam which is directed into an absorption material with a third order polarization property. Such materials will cause a two-photon absorption partial attenuation from the intensified beam when the incident radiation intensity is greater than ambient intensity. A focusing mirror receives the partially attenuated beam and reflects and refocuses the partially attenuated beam back through the absorption material, which now acts as a single photon absorption material to further attenuate the beam. The doubly attenuated beam passes through the focusing lens which recollimates the doubly attenuated beam and directs it to the beam splitter which in turn directs the beam to the receiving device.

Abstract: A method and system for compressing and amplifying light pulses using degenerate cross-phase modulation and degenerate four-wave mixing. A probe pulse and a pair of pump pulses are arranged so as to copropogate in condensed matter with the pump pulses having the same frequency as the probe pulse. The first pump pulse overlaps with the front end of the probe pulse while, the second pump pulse overlaps with the tail end of the probe pulse. The probe pulse is linearly polarized. The pump pulses are orthogonally polarized relative to the probe pulse so that they can be filtered out using a polarizer and have a greater intensity than the probe pulse. The propagation constant mismatch between the probe pulse and the pump pulses is equal to about zero.

Abstract: A method of making a photochromic polysiloxane includes the steps of forming a photochromic spironaphthooxazine monomer including an alkene terminated side and, by addition reaction, covalently bonding the alkene carbon to [SiH] moieties of a siloxane polymer. Novel spironaphthooxazine monomers and photochromic polysiloxanes are disclosed.

Abstract: An intensity sensitive optical switch is described which comprises a nonlinear thin film Kerr material deposited on a conducting surface.

Abstract: The invention relates to a spatial light modulator device comprising a photo-refractive crystal addressed by means of a write light beam and a read light beam. The crystal is placed in the cavity of an interferometer system having a transmittivity-optical path length characteristic of steep slope so as to give rise to a dynamic range of maximum transmittivity variation for minimum variation in the refractive index or optical path length of the photo-refractive crystal. The device is applicable to conoscopic holography systems of large dynamic range and to pattern recognition in real time.

Abstract: A color image display apparatus includes: an image recording medium comprising a recording layer capable of selectively forming a light-scattering state and a transparent state, and a color filter having a pattern of plural color segments operatively associated with the recording layer, a light source, a viewing position, and display means for selectively sending to the viewing position a colored optical image composed of scattered light having passed through the recording layer. The display means may include direction means for directing light from the light source to be incident to the recording layer in a direction not normal to the recording layer.

Abstract: Method and apparatus for limiting optical radiation to an optical sensor are disclosed for protecting the sensor against damage from high intensity optical radiation. A fixed electric field is established between a pair of spaced electrodes by connection of the electrodes to a DC voltage source. Small solid particles oscillate back and forth in the electric field between the electrodes. Incident optical radiation is focused at a focal plane at the oscillating solid particles, and energy transmitted through the oscillating particles is focused at the optical sensor. The transmittance of the particle-containing space is substantially constant for incident optical radiation intensity up to a threshold level below which the sensor is undamaged by the radiation.

Abstract: This invention relates to a device for the protection of eyes, electro-optical sensors and sensitive materials against high energy light beams, in which the incidence of a high energy light beam on the element to be protected is detected by a warning sensor. The warning sensor triggers a light source to provide a light beam which, with minimal delay, causes a diminution in the transmissivity of a protective element interposed in the beam path of the high intensity light beam. Due to the extremely rapid response time of these components, the protective response of the invention adapts almost immediately to changes in the intensity of an incident high energy light beam, thereby providing necessary protection and a prompt return to normal transmissivity upon termination of the potentially damaging radiation.

Abstract: A photochromic material adapted for coating light transmissive materials. The photochromic material contains photosensitive silver halide crystals having dimensions in the range of approximately 50 Angstroms to 800 Angstroms. The silver halide crystals are surface doped with copper ions and another sensitizer selected from mild reducing agents, thioethers, or sulfur-bearing ions and are treated with an agent to accelerate the forward reaction and control the reverse reaction. The accelerants are ions selected from the group consisting of cobalt, chromium, manganese, magnesium, and rare earth metals such as cerium, samarium and europium. The agent for controlling the reverse reaction is one that confers electrical conductivity on the material and while to this end glycerol containing a high concentration of metal ions, methane sulfonic acid and benzyltrimethyl ammonium chloride are useful, the preferred agent is phosphoric acid.

Abstract: A configuration or system of lenses for use in an arc welding environment variably filters light so that the dramatic contrasts of light present in the welding area are reduced for better remote viewing. A photochromic lens forms a negative image of the welding area. The negative image of the photochromic lens serves as a variable density optical filter to reduce the brightness of the image incident upon the photochromic lens. A first lens initially gathers and focusses the light upon the photochromic lens. Subsequent lenses further prepare the image for camera reception by eliminating ultraviolet (UV) light, by eliminating light at spectral lines, and/or by enhancing the depth of field of the image.

Abstract: An optical device that is optically neutral to normal light but absorbs highly collimated light is formed as a mosaic of optical cells. Each cell has at least two refracting surfaces and a non linear material at a focus internal to those surfaces. In one form, the cell comprises two pairs of lenses with a layer of non-linear light absorbent material interposed between the lenses of each pair. The lens elements can be one-power telescopes. A first lens element focuses highly collimated light at its entrance aperture on the non-linear layer. The intensity of the focused light causes the non-linear layer to become opaque or reflective and thereby reduce, or substantially block, the transmission of highly collimated light. The second pair of lenses inverts the re-collimated light exiting the first lens pair.

Abstract: An optical switching device employs a rare earth bis-phthalocyanine having good third-order nonlinear susceptibilities. In a preferred optical switch, the rare earth bis-phthalocyanine is employed as a nonlinear optical material body that fills the space between two partially reflecting mirrors. When light incident on the switch is below a given intensity level, light passes through the switch and the switch is in an open state. When light is above a given intensity level, light is trapped in the nonlinear optical material and the switch is in a closed state.

Abstract: Disclosed is an organic nonlinear optical material comprising a compound having a conjugate main chain in the molecule and having donor groups D and acceptor groups A added onto the conjugate main chain in the sequence of . . . , D, D, A, A, D, D, . . . , in which the distance between adjacent D's and the distance between adjacent A's are shorter than the distance between adjacent D and A with respect to the distance between the atoms on the main chain to which the respective groups are bonded.In this organic nonlinear optical material, since electron wave functions are modified, enhanced quadratic and cubic nonlinear optical effects can be attained. Accordingly, the organic nonlinear optical material can be advantageously utilized for an electro-optical element and an optical-to-optical element.

Abstract: A method of manufacturing an optical disk on which light-emitting regions for absorbing a laser beam and emitting light of a wavelength different from that of the laser beam and reflection regions for reflecting a laser beam irradiated thereon are alternately arranged, comprises the steps of forming a reflection layer on a transparent substrate, forming a plurality of through holes in the reflection layer, and filling a light-emitting layer consisting of a fluorescent member in the through holes, thereby a high density optical disk can be manufactured.

Abstract: Optically sensitive materials (18) such as sensors or the human eye are passively protected against overexposure to high intensity light (20) in the visible region using a reverse saturable absorber (14) comprising one of a class of organic compounds known as buckminsterfullerene, such as C.sub.60. As the intensity of incident light increases, the intensity of transmitted light also increases up to a saturation level, but above the saturation level, the transmitted light intensity remains substantially constant even with increasing intensity of incident light. C.sub.60 has an unexpectedly low threshold for optical limiting action, is thermally stable, and is easily manufacturable into devices.

Abstract: A light-modulated photoconductor, exhibiting a variable permittivity, provides the basis for various instrumentation devices and methods. In one embodiment, the light-modulated photocondcutor is used as a dielectric between conductive plates to provide a light-modulated capacitor (photocapacitor). One of the conductive plates may be transparent to facilitate application of the modulating light to the photoconductor. The light-modulated capacitor may be used for numerous applications, such as instrumentation used to, e.g., measure the work function of surfaces during processing or as a non-contact voltmeter. In another embodiment, the light-modulated photoconductor is used as a mirror or lens wherein the index of refraction is optically modulated. Such light modulated lens or mirror assembly may be used as a beam steering device, e.g., a solid state infra-red (IR) beam steering device.

Abstract: A light valve comprising a first transparent electrically insulating layer, a first transparent electrically conductive layer, an electro-optic imaging medium layer, a dielectric mirror, a light blocking layer comprising an organic dye or organic pigment, a photoconductor layer comprising selenium, a second transparent electrically conductive layer and a second transparent layer. This light valve may be utilized in systems which include an imaging light source and a read-out light source.

Abstract: The invention is a camouflage system for the exterior of a military vehicle. The system includes a set of photoreactive lenses on the vehicle, the lenses having an irregular topography and a thin anti-reflection film on the faces of the lenses. The system reduces or eliminates contrast between illuminated and shadowed panels of the vehicle so that the vehicle more thoroughly blends into the background against which the vehicle is viewed.

Abstract: Enhanced energy transfers are achieved between optical beams by operating at wavelengths in the near-bandgap region of a photorefractive material, and employing an electrorefractive effect previously proposed only for single beams. An electric field is applied across a photorefractive medium of sufficient intensity to induce an electrorefractive coupling and consequent energy transfer between the beams. Gain enhancements are possible by orienting the photorefractive medium to obtain an electro-optic as well as an electrorefractive effect, and by a moving grating technique. The direction of energy transfer between the beams is controlled by the electric field direction, and can be reversed by reversing the field. Operation in the infrared region is made possible with semi-insulating materials. Applications include optical switches, amplifiers and phase conjugators.

Abstract: A real-time, pre-detection optical dynamic range compression system uses a photorefractive crystal, such as BaTiO.sub.3 or LiNbO.sub.3, in which light induced scattering from crystal inhomogeneities of the optical input occurs as a nonlinear function of the input intensity. The greater the intensity, the faster random interference gratings are created to scatter the incident light. The unscattered portion of the optical signal is therefore reduced in dynamic range over time. The amount or range of dynamic range compression may be controlled by adjusting the time of application of the unscattered crystal output to the photodetector with regard to the time of application of the optical input to the crystal.

Abstract: A transient optical element is created by providing a body of a third order non-linear material and then passing a pulse of light through the body of non-linear material. The pulse of light has a cross-sectional area corresponding to the cross-sectional area of the transient optical element to be created and power sufficient to induce an index of refraction change over the portion of the body of non-linear material through which it passes. The portion of the body of non-linear material having the induced index of refraction change constitutes the transient optical element with the duration of the transient optical element depending on the response time of the non-linear material and the duration of pulse of light. Typical optical elements that can be so created include prisms, lenses, gratings, mirrors, beamsplitters and wave guides. By forming a plurality of optical elements within the third order non-linear material rather than simply a single optical element, a transient optical circuit can be created.

Abstract: Apparatus for selectively limiting the response of an auxiliary liquid crystal light valve which is used in a dual liquid crystal light valve laser optics system for correcting inherent liquid crystal light valve distortion by isolating an atmospheric reference beam from the main laser beam in the auxiliary correction system. Two types of isolation are provided: dual bandwith and dual polarization. In the former, the response bandwidth of the auxiliary liquid crystal light valve is shifted to prevent overlap with the bandwidth of an atmospheric reference wavefront. In the dual polarization form of isolation, provision is made for rotating the polarization of only one of the two interacting beams.

Abstract: An optical device structure having enhanced resistance to damage by invasive laser radiation is described which comprises a thin layer of optical switching material, such as VO.sub.2, deposited onto a lattice matched substrate. A method for fabricating the structure is also described.

Abstract: An integrated adaptive optics apparatus for processing wavefront errors. In a preferred embodiment, a modified liquid crystal light valve (LCLV) is used as an integrated wavefront sensing and wavefront control system. A remote reference aberrated wavefront 10, passed through the liquid crystal layer and reflected, is then fed-back in part to the rear surface of the liquid crystal light valve 12, after combination with a local reference plane wave 16. The resulting interference pattern is incident on the photosensitive layer 26 of the LCLV, causes commensurate index changes in the liquid crystal layer, and adapts the LCLV for performing aberration correction. In an alternative embodiment, a second laser beam 11 may be predistorted by passing it through the adapted liquid crystal layer in order to compensate in advance for atmospheric path disturbances. The present invention provides an adaptive optics correction system having high spatial resolution.

Abstract: For limiting the maximum radiation intensity of a radiation source, in particular a laser, a transparent breakdown cell (4, 10, 17) with defined breakdown threshold value is placed within the ray path of the radiation source (2, 8, 15).

Abstract: A lens (12) converges a light beam (16) into a light absorbing body (14) having a material which exhibits reverse saturable optical absorption distributed therein with a non-uniform concentration. The concentration is maximum at the focal point (20) of the converged light beam (16), and decreases toward the lens (12) with a distribution selected in correspondence with the optical gain of the converged light beam (16) to limit the local fluence of the light beam (16) propagating through the absorbing body (14), and the output energy of the light beam (16), to predetermined maximum values. The non-uniform concentration further produces a self-protecting effect by causing the region of maximum fluence of the converged light beam (16) to shift toward the lens (12), thereby protecting the region of highest optical gain and highest molecular concentration, as the input energy of the light beam (16) increases.

Abstract: Optically nonlinear aromatic carboxylic acid cocrystals are provided of the formula: ##STR1## wherein each R is CN or NO.sub.2, n is 1-4, m is 1-3 and X and Y are individually (C.sub.1 -C.sub.3)alkyl, (C.sub.1 -C.sub.3)-alkanolyl, (C.sub.1 -C.sub.3)alkoxycarbonyl, ar(C.sub.1 -C.sub.5)alkyl, aryl, (C.sub.1 -C.sub.3)alkoxy, hydroxy, halo or mixtures thereof.

Abstract: A photochromic material adapted for coating light transmissive materials. The photochromic material contains photosensitive silver halide crystals having dimensions in the range of approximately 50 Angstroms to 800 Angstroms. The silver halide crystals are surface doped with copper ions and another sensitizer selected from mild reducing agents or sulfur-bearing ions. The crystals are dispersed in a protective polymer that does not irreversibly bind halogen.

Abstract: An electrochromic resin composition comprising (A) 100 parts by weight of a network comprising a crosslinked polymer containing 4,4'-diaminodiphenylmethane units in a form in which the amino groups in the formula are quaternized, and (B) 5 to 150 parts by weight of an electrolytic material uniformly dispersed in the network (A). The crosslinked polymer containing the units with the amino groups therein being in the quaternized state is useful as an electrochromic or photochromic material.

Abstract: Non-linear optical materials, i.e., those optical materials whose indices refraction depend on input radiation intensity, are few and of low non-linearities; this invention uses various metallic patterns on a transparent substrate, with non-linear elements between parts of the patterns, to function as an artificial dielectric. These elements may take the form of metal-oxide-metal tunnel diodes, Schottky diodes, p-n junction diodes, superlattice structures, and non-linear capacitors.

Abstract: A single material (not a multi-element structure) spatial light modulator (50) may be written to (30), as well as read out from (80), using light (20). The device has tailorable rise and hold times dependent on the composition and concentration of the molecular species used as the active components. The spatial resolution of this device is limited only by light diffraction as in volume holograms. The device may function as a two-dimensional mask (transmission or reflection) or as a three-dimensional volume holographic medium. This device, based on optically-induced electron transfer, is able to perform incoherent to coherent image conversion or wavelength conversion over a wide spectral range (ultraviolet, visible, or near-infrared regions).

Abstract: Devices for and method of generating coherent second harmonic light radiation. The devices comprise a laser source of coherent light radiation at a fixed fundamental frequency, an acentrically crystalline, achiral, straight-chain N-nitrophenyl carbamyl compound, means for directing the output radiation of the laser onto the acentrically crystalline, achiral, straight-chain N-nitrophenyl carbamyl compound, and output means for utilizing the second harmonic frequency. N-nitrophenyl carbamyl compounds, and acentric crystals thereof that are capable of being used in the aforementioned devices and method, are also described herein.

Abstract: A light-emitting apparatus comprised of a light-emitting element having a P-N junction light-emitting section in which the decrease in the intensity of the light from the light-emitting element can be maintained at a more or less constant level regardless of changes in the temperature of the light-emitting section.

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: A variable interval electromagnetic pulse train generator having a semiconductor substrate on which is mounted on one surface thereof a plurality of spaced apart electrodes and on another surface thereof an electrode base plate. A voltage source is connected to each of the plurality of spaced apart electrodes while the space between electrodes have optical pulses directed thereon. By controlling the voltage applied to the electrodes and the optical pulses directed between electrodes the pulse train generator is capable of emitting a series of variable, spaced apart electromagnetic pulses.