Abstract: Image derogating optical noise due to light scattering of an object under examination, embedded in a light scattering medium, is substantially reduced by passing a modulated signal laser beam through the scattering medium, and interfering the emerging signal with a coherent modulated reference beam to produce a hologram in a photorefractive member of the object, which in turn is read out of the crystal by a third unmodulated coherent beam to retrieve a clear image of the object. A smart pixel image convertor light valve may be substituted for the photorefractive member.

Abstract: Systems and methods for steering a complex, spatially-modulated incident beam of coherent light to gain access to data locations in a holographic memory cell (HMC). One of the systems includes: (1) a reflective element, locatable proximate a first focal plane of the incident beam, (2) a rotational steering mechanism, coupled to the reflective element, that orients the reflective element according to a desired rotational angle to steer the incident beam in a desired direction and (3) a refractive element that refracts the beam reflected from the reflective element to create a second focal plane for the beam, the HMC locatable proximate the second focal plane and rotatable about an axis of a plane thereof to receive the beam at a location thereon that is a function of the desired direction and an angular position of the HMC.

Abstract: A system for converting an image into a hologram formed from diffraction gratings includes obtaining image data for each pixel in an image to be converted, putting it into digital form and using the image data to control portions of a laser beam split into a reference beam and at least one object beam. The diffraction gratings are formed by an interference pattern of a reference beam and at least one object beam intersecting on the surface of a photoresist material on a pixel-by-pixel basis. Modulation of at least one object beam and adjustment of the angle at which that beam interferes with the reference beam on the photoresist material is used to reflect image data for each pixel of the image being converted into a hologram consisting of diffraction gratings.

Abstract: Apparatus and methods are disclosed for spatially routing an optical pulse (data pulse) of an electromagnetic radiation and containing a specific address temporal profile and possibly additional data. Routing generally involves a unit of active material that is programmed using one or more input beams or pulses of the electromagnetic radiation providing address (i.e., waveform-discriminating) and directional (i.e., pulse routing) information to the active material. During programming, a spatial-spectral grating is created by optical interference on or in the active material of the input pulses encoding the address and directional information pertinent to the data pulse.

Abstract: A plurality of holograms are simultaneously angularly and spatially multiplexed within a storage medium by writing the holograms at different locations within the storage medium using reference and object beams directed thereto via cooperating reference beam and object beam scanners, respectively. The simultaneously angular and spatially multiplexed holograms are subsequently read-out by directing a reference beam through a desired location within the storage medium using the reference beam scanner. The reference beam is directed from the storage medium to a phase conjugator which conjugates the phase of the reference beam and directs the phase conjugated reference beam back to the same desired location within the storage medium so as to excite a corresponding conjugate object beam which is then directed onto a detector array.

Abstract: Holograms within an array are recorded and/or read out by use of a reference/read out beam produced by illumination of a phase mask.

Abstract: A tight packed array of amplitude controlled in-phase light emitters produces dynamic real holographic images. A partially reflecting mirror is applied to a planar array of amplitude controlled laser diode emitters which are stimulated by each other. The emitters are forced into phase with each other by partially reflecting light energy from adjacent row and column elements onto each other. Incident energy stimulates the element receiving the energy to fire in phase with the incident energy. The array may be forced in phase by directly illumination from a master laser. A single laser is used to illuminate a flat surface containing an array of transmissive apertures which act as emitters. Amplitudes are controlled by liquid crystals. Light from the emitters forms an image which changes according to amplitudes of the individual emitters. Optical focal plane reducers reduce the effective inter element spacing.

Abstract: A method and apparatus are provided for reducing speckle noise in images read out from holographic memories. An image recorded in the memory is read out using a multiple component readout beam, with each component having the same horizontal orientation but a different vertical orientation. Because the Bragg effect is pronounced only in the horizontal direction, the readout beam components all access the same stored image. Each readout beam component is set to oscillate at a slightly different frequency such that the smallest frequency difference is greater than the reciprocal of the output detector response time. The multiple oscillating readout beam components can be produced by an acoustooptic deflector driven by a wideband electrical signal. The memory readout comprises multiple reconstructions of the desired image, with each image reconstruction oscillating at a slightly different optical frequency.

Abstract: The invention is embodied in a method of recording successive holograms in a recording medium, using at least a fan of M waves along at least a first axis with a separation angle between adjacent waves and directing the fan of M waves as a reference beam along a reference beam path onto the recording medium, successively modulating a wave with a succession of images to produce a succession of signal beams along a signal beam path lying at a propagation angle relative to the reference beam path so that the signal and reference beams intersect at a beam intersection lying within the medium, the beam intersection having a size corresponding to beam areas of the reference and signal beams, producing a succession of relative displacements in a direction parallel to the first axis between the recording medium and the beam intersection of the signal and reference beam paths in synchronism with the succession of signal beams, each of the displacements being less than the size of the intersection whereby to record suc

Abstract: Novel multiplexed volume holographic optical elements for the development of highly multiplexed photonic interconnection and holographic memory systems with maximum optical throughput efficiency and minimum crosstalk, based on parallel incoherent/coherent double angularly multiplexed volume holographic recording and readout principles, are disclosed. These principles further provide for arbitrarily weighted and independent interconnections, which are of potential importance in the development of densely interconnected photonic implementations of neural networks, photonic interconnection networks for telecommunications switching and digital computing applications, optical information processors, and optical memories. Utilization of the principles that are key features of this holographic element allows for the single step transfer of all or part of the information stored in a three-dimensional holographic storage device to a second such device in a single exposure step.

Abstract: In a method for mitigating cross-talk in high-efficiency, angle-multiplexed holograms stored in photorefractive media, a plurality of uniformly low-efficiency holograms are first stored within a common holographic storage medium and then simultaneously exposed to a like plurality of mutually incoherent reference beams. Each reference beam effects enhancement of its corresponding hologram so as to increase the level thereof while also minimizing cross-talk between holograms.

Abstract: A method is disclosed to holographically mark an object in a way that the mark cannot be removed, reproduced, or transferred covertly. The mark can be read from a distance so that the part can be verified as the one and only original. The mark is applied to an undulating or rough surface of the object. The method requires that a reference wave be reflected from the surface and holographically recorded. This wave is then regenerated so that it travels in the opposite direction. This regenerated wave is itself reflected from the surface to form a collimated reference wave which, together with an object wave, is used to form the holographic mark. The recorded image cannot be observed without the presence of the surface itself.

Abstract: A holographic storage system and method are provided in which a light source (12) is used to generate a coherent light beam which is split into a reference beam (18) and an object beam (20). The reference beam (18) is directed to the holographic storage medium (22) through use of a reference beam multiplexer (24). The object beam is encoded with a pattern encoder (34) and directed to the holographic storage medium (26). During read out, the object beam is reconstructed and detected by an optical detector (40).

Abstract: A method and apparatus for holographic storage with combined orthogonal phase codes and random phase codes are provided in which a reference beam (18) is encoded with a combination orthogonal phase code and random phase code by a phase encoder (28). A data pattern is imposed on an object beam (20) by pattern encoder (38). Both the reference beam (18) and the object beam (20) are directed to a particular stack site on a storage medium (32).

Abstract: A space light modulating apparatus and a stereoscopic display apparatus which are used in a rewritable hologram stereoscopic display. A solid image can be properly displayed by a phase distribution of a low spatial frequency. A plurality of flat space light modulating units, each having a predetermined area for performing a wave front conversion while setting a position near the position of a cross point (center position) of a normal line from a virtual display surface of a non-flat shape to display the phase distribution into a producing position of a solid image, are arranged along the virtual display surface such as a cylindrical surface or a spherical surface.

Abstract: A space light modulating apparatus suitable for reconstruction of an electronic 1-dimensional hologram having no movable section. A predetermined display region is divided into a plurality of stripe-like regions each having a screen width L.sub.x in the horizontal direction and a microwidth .DELTA.L.sub.y in the vertical direction. A plurality of pixels each having a dimensional ratio such that a lateral width in the horizontal direction is enough smaller than a vertical width in the vertical direction are arranged in each of the stripe-like regions. Further, a driving element for controlling the optical characteristics is provided every pixel. A dimensional ratio in the vertical and horizontal directions of the pixels arranged in each stripe region is equal to or larger than 30:1.

Abstract: This is a processing module which may be used for parallel processing. Multiple software configurable optical interconnections provide for high speed processing which preferably use computer generated holograms to communicate among multiple processing elements. Other methods and devices are disclosed.

Abstract: The present invention is a laser protection window for protection from uncontrolled laser illumination. This laser protection window includes a holographic optical element forming a reflection hologram at the wavelength of the expected laser threat. A set of channel plates opaque to the expected laser threat wavelength are disposed at right angles to the holographic optical element in order to block laser illumination arriving outside the cone of protection of the holographic optical element. These channel plates may be vertically disposed to provide protection against mostly horizontally disposed laser threats. In alternative embodiments, the channel plates include both horizontally and vertically disposed plates or plates disposed in polygonal cross section to cover the entire area of the laser protection window.

Abstract: A phase modulating device for spatially modulating a phase of an incident light beam is of a binary type having a plurality of rectangular protrusions on a cross section thereof. A distribution is provided to a diffraction efficiency at each point of the phase modulating device by varying a width of each protrusion.

Abstract: This is a programmable processing system which comprises: one or more computer networks each of the networks has at least one population of processor nodes; at least one population of storage nodes; and at least one switch to provide transfer of information between the processor nodes and the storage nodes. Each processor node has at least one processing module comprising spatial light modulators; processors; and at least one hologram. Other methods and devices are disclosed.

Abstract: Holographic images are constructed in a recording material in accordance with a temporal interleaving technique in which a first set of images is constructed for a predetermined first imaging time with a predetermined first time gap being defined between each of the images. Thereafter, in accordance with a subsequent predetermined sequence a subsequent set of images is constructed into the same predetermined location. The image sets have at least one member in common. In one aspect all of the images are constructed into the same predetermined defined region of the holographic recording material (an angle hologram). In another aspect the predetermined defined region into which each of the images is constructed is separate from all other regions of the holographic recording material (a spatial hologram).

Abstract: The present invention concerns a holographic process including a stage consisting in producing the hologram of a point P thank to an optical device including a crystal (131) and two polarizers (132,135) placed respectively before and after the crystal (131), characterized by the fact that it includes in addition the stages consisting in: 1) separating the answers of the optical system corresponding to two different polarizations and 2) combining both these answers in order to obtain a signal which depends only on the distance between the point P ant the optical device. The invention concerns also a device which allows the implementation or this process.

Abstract: A holographic storage media (10) is fabricated from a thin layer of photopolymer recording media. The photopolymer recording media is disposed between a substrate (48) and a capping layer (56). The media (10) is divided into a plurality of storage regions (54), which are formed within wells (52) to isolate each of the regions (54). During a record operation, a pumping operation is first performed to remove oxygen molecules from the media by bombarding the select region that is to have an interference pattern recorded therein with photons for a predetermined duration of time. Once the oxygen molecules have been depleted, then a data beam is generated with data superimposed thereon and a reference beam generated for interference with the data beam in the storage region (54). This results in the recording of an interference pattern.

Abstract: A hologram manufacturing apparatus and a hologram manufacturing method for manufacturing a hologram optical device by a split exposure method are disclosed. The manufacturing apparatus comprises light shield means having a spatial light modulator having a light transparent area and a light non-transparent area thereof controlled corresponding to an input signal, and drive means for driving the spatial light modulator by supplying the signal to the spatial light modulator. The light shield means is arranged closely to a photosensitive material.

Abstract: An optical apparatus for controlling a wave front of a coherent light including at least a coherent light source, an electrically addressable liquid crystal device having a plurality of pixels receiving the light from said light source, and a signal generator for recording a complex amplitude distribution or hologram on the liquid crystal device.

Abstract: A pattern recognition apparatus and a method for operating same. The apparatus includes a volume holographic medium (4) having a plurality of Fourier-space volume holograms representing pattern templates stored within. The apparatus further includes a spatial light modulator (1) and a phase encoder (2). The phase encoder has an output optically coupled to the medium by a first Fourier transform lens (3). The spatial light modulator spatially modulates a spatially uniform laser beam (7) in accordance with an unknown pattern. The two-dimensional phase encoder causes the spatially modulated laser beam to be spatially distributed prior to application to the medium. The apparatus also includes a detector (6, 11) having an input optically coupled by a second Fourier transform lens (5) means to an angular spectrum of plane waves generated by the medium in response to the output of the spatial modulator, phase encoder, and first Fourier lens.

Abstract: A peristrophic multiplexing system directs a signal light beam and reference light beam onto a selected recording spot in the recording medium. The light beams collectively define a plane of interaction. Either the recording medium or the signal/reference beam are rotated relative to the other through a succession of peristrophic multiplexing angles. Those angles cause relative rotation about an axis that is not perpendicular to the plane of selectivity. The rotation occurs contemporaneously with the modulating of the hologram on the medium.

Abstract: The current limits of resolution of multi-element optical systems are exceeded by reducing the number of elements while introducing at the critical aperture a blazed transmission grating having grating rings of low bending power defined by multiple plateaus. By illuminating the optical train with monochromatic light that constitutes a multiplicity of distributed sources having a substantial temporal coherence but spatial incoherence and by varying the slopes and widths of the grating rings, local phase delays are introduced that adjust aberrations in the optical system, providing an aligned composite wavefront. The system and method may be used for presenting an image, as for a wafer stepper, or for viewing an image, as in a microscope.

Abstract: Multiple volume holograms are recorded by changing the incidence angle of the reference beam at one wavelength. The stored holograms are reconstructed at another wavelength by using the reference beam oriented at the proper incidence angle. The proper holographic data are retrieved by pre-formatting or post-formatting the holographic data to be recorded or reconstructed. This usage of using different wavelengths for recording and reconstruction are independent of the scanning mechanisms for the reference beam. Utilization of holographic memories for storage and retrieval of data, and correlations can make use of this invention.

Abstract: A technique for all-optical Code Division Multiple Access (CDMA) system based on optical holography is disclosed. In this technique the energy of an incoming information light signal is spread over a spatial domain by a two-dimensional spatial encoder which includes a mask having regions of first and second transmission characteristics corresponding to the unique code assigned to a particular source. Subsequent decoding, which is accomplished by an optical matched filter through the use of a hologram, spatially despreads the energy of the information light signal and produces a focused light beam which serves as input to a code division detector.

Abstract: A neural network has inputs formed by square array of optical modulators M.sub.ij and outputs by optical detectors D.sub.ij coupled to threshold comparators. A holographic plate includes a spatial modulator whose elements are controlled by a controller to form an array of optical beams from a coherent optical source. Each optical beam optically interconnects a modulator M.sub.ij with a respective detector D.sub.ij. The weight values of the neural network are provided by the intensities of the optical beams. This obviates the need for an optical weighting mask between an array of light emitting diodes and a detector array allowing a higher density of lower power consumption components and reprogrammability of the network.

Abstract: Novel apparatuses for readout of multiplexed volume holographic optical elements, based on parallel incoherent/coherent double angularly multiplexed holographic recording and readout principles, provide for hologram readout with high optical throughput efficiency and minimal crosstalk. Such holographic element readout apparatuses have applications in photonic interconnections for neural networks, telecommunications switching and digital computing; optical information processors and optical memories; and optical display systems. Embodiments are included that allow incoherent superposition of reconstructed images and simplified parallel readout of the volume holographic optical elements. The apparatuses can read out holographic elements that are either optically or computer generated and that are based on continuous-volume or stratified-volume holographic media.

Abstract: A flexible rejection filter removes coherent radiation from an incoming beam of light. The filter includes a beamsplitter for dividing the transmitted portion into first and second beams. A photorefractive crystal in the paths of the first and second beams couples coherent radiation from the first beam to the second beam. A focal plane detector follows the crystal in the path of the first beam for sensing the incoherent radiation in the first beam, while a beam dump follows the crystal in the path of the second beam for absorbing the coherent radiation of the second beam. Other filter configurations can utilize contradirectional energy coupling or resonator structures in conjunction with photorefractive media.

Abstract: Light from a laser (10) is divided by a beam splitter (12) to provide signal (15) and reference (14) channels. The signal channel light is expanded (11) to illuminate an acousto-optic (AO) device (13). This leads to a spatial distribution of Doppler shifted frequencies. This spatial distribution then illuminates a spatial light modulator (SLM) (19) such that a number of parallel and discrete optical channels (112) emerge. In a local area network (LAN) the optical signal channels are coupled into a single mode optical fibre (22) and then heterodont to the reference laser light from a further optical fibre (23) in an optical coupler (25). In a receiver the modulated light is detected (32) and the detected signal connected to the transducer of an AO device (35). The AO device (35) is illuminated by a receiver laser light (36) and the emerging modulated light is incident on a focal plane detector array (39) where each detector (310) then receives light corresponding to each of the transmitted channels (311).

Abstract: An apparatus 10 for exposing a curved grating pattern of monochromatic light on a photoresist coated semiconductor wafer 12 includes an argon gas laser 14 that outputs a monochromatic light beam 16. This monochromatic light beam 16 is filtered and collimated to produce a monochromatic light beam with a planar wavefront 24. A portion of this planar wavefront passes through a cylindrical lens array 26 and a first baffle slit 30, producing multiple cylindrical wavefront 34 that is incident upon a hypotenuse face 38 of a right angle prism 40. Another portion of the planar wavefront passes through a second baffle slit 32, producing a smaller planar wavefront 36 that is also incident upon the hypotenuse face 38 of the right angle prism 40. A destructive interference between a reflected multiple cylindrical wavefront 92 and a direct planar wavefront 90 inside the prism 40 produces a curved grating pattern of monochromatic light on an adjacent prism face 42.

Abstract: This is a board to transport and convert optical outgoing free-space signals from a spatial light modulator which comprises: at least one detector to process the outgoing free-space signal; at least one signal transmitter to process the outgoing free-space signal; and at least one outgoing optical signal carrier to carry a converted outgoing signal. Other methods and devices are disclosed.

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: 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: A three-dimensional optical recording medium is made of a photo-induced refractive index-changing material or two-photons absorbing material, which is based on photo-dissociation or photopolymerization. An optical information recording apparatus comprises a device for loading a three dimensional recording medium; a device for generating a high coherent optical pulse or a train of partially-coherent optical waves; a device for splitting the optical pulse into two pulse components and causing the two pulse components to propagate in the recording medium from opposite directions to meet at a predetermined three-dimensional position; a device for converging a light beam in the recording medium into a parallel beam; and a device for discretely scanning the meeting position of the pulse components to ensure three-dimensional recording in accordance with information to be recorded.

Abstract: A method for converting a 2-D image into a hologram is set forth. An optical scanner system which measures the primary color intensity of a selected pixel and forms an indication thereof is disclosed. The location of the pixel is output as XY coordinate data. The location and color data is stored in memory, and the memory is thereafter retrieved. A pixel is located on a blank, and a laser beam split into four equal segments is focused along four separate pathways to the pixel location. Interference fringes formed at the point of convergence on the blank enables transfer of a single pixel, and multiple pixels are transferred so that the entire image is reproduced.

Abstract: A photosensitive element 46 absorbs at least a portion of an incident write beam 40, causing a spatially varying electric field to be applied across a layer of a ferroelectric liquid crystal (FLC) 48, thereby forming a pattern of local polarizations corresponding to the spatially varying electric field. In one embodiment, a signal beam is modulated with a phase variation characteristic of a particular aberrator. The signal beam is then combined with a substantially plane wave reference beam to form interference fringes. These interference fringes are directed as a write beam onto photosensitive layer 46, forming a hologram in FLC layer 48 which can be read optically. An incident beam of light can be diffracted by a hologram formed in the FLC layer, thereby modulating the incident beam of light with the phase variations comprising the hologram.

Abstract: A variable weight optical interconnector is disclosed to include a projecting device and an interconnection weighting device remote from the projecting device. The projecting device projects a distribution of interconnecting light beams when illuminated by a spatially-modulated light pattern. The weighting device includes a photosensitive screen provided in optical alignment with the projecting device to independently control the intensity of each projected interconnecting beam to thereby assign an interconnection weight to each such beam. Further in accordance with the present invention, a highly-interconnected optical neural network having learning capability is disclosed as including a spatial light modulator, a detecting device, an interconnector according to the present invention, and a device responsive to detection signals generated by the detecting device to modify the interconnection weights assigned by the photosensitive screen of the interconnector.

Abstract: A near-real-time holographic display for operations at a remote work site where a three dimensional database is collected with a laser range scanner. The database is then divided into discrete two dimensional segments or depth planes. A holographic recording material is then sequentially exposed to multiple depth planes through a stack of three spatial light modulators in a multiplane exposure process. This procedure is repeated for all depth planes in the database. The holographic recording material is then rapidly developed for viewing of the remote work site in a holographic image that simulates natural vision.

Abstract: An optical logic operation apparatus includes an optical induction refractive index crystal having first and second planes parallel to each other and a device for inputting a coherent probe light from the first plane of the crystal. At least one of the first light output from the first plane of the crystal and the second light output from the second plane of the crystal is taken out so that one of the first and second lights is amplified by the two-wave coupling of the probe light reflected by the second plane and the probe light inputted from the first plane and the other light is attenuated likewise by the two-wave coupling. The inputted image is projected onto the crystal by use of light incoherent to the probe light. With the incidence of the incoherent light, a gain distribution corresponding to the inputted image is generated in the crystal so as to modulate the first and second lights spatially.

Abstract: In processes of holography using bacteriorhodopsin-based recording media, it is essential to design the signal-to-noise ratio to be as favorable as possible. This is achieved by recording the hologram using circularly polarized light and reconstructing the hologram by using linearly polarized light, specific beam components being selected as a function of polarization in the beam path of the reconstructed hologram. The process is suitable both for purely holographic applications and also for other processes which include one or more intermediate or partial steps involving holography.

Abstract: A system for the display of images comprising:a spatial modulator of light receiving a first light beam and retransmitting a modulated beam;an energy transfer device receiving the modulated beam and a second light beam and transferring the energy from the second light beam towards the modulated beam.

Abstract: A radially symmetric iterative discrete on-axis hologram has a high diffraction efficiency for a correspondingly small f-number. The radially symmetric hologram has a plurality of concentric constant radial phase fringes. Each fringe has a predetermined plurality of radial phase rings and each fringe corresponds to a predetermined plurality of radial phase transition points and a radial phase value between the radial phase transition points. The radially symmetric iterative discrete on-axis hologram also has radial phase fringes with a predetermined number of phase levels, at least two adjacent fringes have a phase level difference which is greater than one and less than the predetermined number minus one. The radially symmetric iterative discrete on-axis hologram is fabricated by determining a plurality of concentric fringes of constant phase with a plurality of radial phase transition points and radial phase values between the radial phase transition points for each concentric fringe.

Abstract: A three dimensional display system includes a laser for generating a laser light signal. The signal is expanded and collimated using a traditional lens system and is directed to an acousto-optic modulator wherein it is modulated to generate a three dimensional image such as a holographic image. The modulation signal for the modulator is provided by a data processing system. The data processing system applies signals to the modulator that encode a diffraction pattern. The diffraction pattern is realized by the modulator upon application of the signals and the three dimensional image is produced by the modulated light signals. The image is demagnified by a demagnifier, and subsequently, imaged by a viewing lens. A horizontal scanner continuously multiplexes segments of the holographic image and compensates for the motion of segments across the modulator. A vertical scanner is provided to properly vertically position horizontal lines of the holographic image.

Abstract: A mirror and system for wavefront control includes a piezoelectrically active pellicle with a conductive front mirror surface, and an electron gun for depositing charge on the rear surface of the pellicle. The pellicle is formed of facing plies of polyvinylidene fluoride having opposite poling, so that efficient bimorph actuation is achieved while maintaining substantially constant pellicle thickness and stable x-y planar position coordinates. A phase corrector plate provides a fixed flatness correction for irregularities of the mirror surface, and an initial charge distribution is applied to achieve a reference mirror contour. Potentials above and below a front surface reference potential, and different frame rates, are achieved by controlling the electron energy to selectively charge by primary or secondary charging processes. A feedback system may establish the initial reference contour, and thereafter effect real time wavefront adjustment of a beam reflected from the front mirror surface.

Abstract: A programmable optical interconnection apparatus and method in which a plurality of spatial light modulators (SLM) form a plurality of spatially modulated beams from a data signal. A hologram is responsive to the spatially modulated beams for generating at least two destructively interfering coherent beams at a first optical detector to thereby disconnect the data signal therefrom, and for simultaneously generating at least two constructively interfering coherent beams at a second optical detector to thereby connect the data signal beam thereto. The hologram is preferably a computer generated thin hologram which does not rely on Bragg diffraction. A low cost, high density, high efficiency programmable optical interconnect is thereby provided.