scispace - formally typeset
Search or ask a question

Showing papers on "Spatial light modulator published in 1991"


Patent
30 May 1991
TL;DR: In this article, a digitized display system providing multiplexed color beams at one frequency less than the critical flicker frequency for the human eye with each color beam being provided at a higher frequency.
Abstract: A digitized display system providing multiplexed color beams at one frequency less than the critical flicker frequency for the human eye with each color beam being provided at a higher frequency. The beams are directed at a spatial light modulator. The individual light beams from the spatial light modulator is directed toward a display surface.

301 citations


Patent
18 Dec 1991
TL;DR: In this paper, a method for increasing the brightness of a scene in a color projection system is disclosed, where a portion of the total illumination time is allocated to white light to raise the overall brightness.
Abstract: A method for increasing the brightness of a scene in a color projection system is disclosed The brightness can be increased in both temporal and spatial filtering systems In a temporal system, a portion of the total illumination time is allocated to white light to raise the overall brightness In a spatial system, part (26) of the illuminated area (18) is allocated to white light The parts (20, 22, 24, 26) could be allocated as regions on a spatial lights modulator (18), or a spatial light modulator could be dedicated to that area to use white light

286 citations


Patent
26 Jun 1991
TL;DR: In this paper, a visual display system with a spatial light modulator with individually controllable elements is described, where a source of random polarity light is utilized to direct light onto the modulator.
Abstract: A visual display system having a spatial light modulator with individually controllable elements. Each element capable of producing an individual light beam directed toward a display surface. A source of random polarity light is utilized to direct light onto the modulator.

256 citations


Patent
26 Jun 1991
TL;DR: In this paper, a digitized display system providing a three dimensional image utilizing a display including a multi-frequency sensitive material and a spatial light modulator with individual controllable elements.
Abstract: A digitized display system providing a three dimensional image utilizing a display including a multi-frequency sensitive material and a spatial light modulator with individual controllable elements. The spatial light modulator can be a deformable mirror device.

224 citations


Patent
03 Jul 1991
TL;DR: In this paper, a spatial light modulator has an array of deformable mirror cells with two or more memory cells associated with each mirror cell, and the array could be subdivided into several arrays with its own decoders as desired.
Abstract: A digitized video system utilizes a spatial light modulator which has an array of deformable mirror cells with two or more memory cells associated with each mirror cell. A first decoder address one memory cell associated with most of the mirror cells of the array to display an image. A second decoder address one memory cell of each memory cell in the array to allow information to be stored therein. The array could be subdivided into several arrays with its own decoders as desired.

222 citations


Patent
30 May 1991
TL;DR: In this article, a digitized video system utilizing a spatial light modulator which includes deformable mirror devices to form an image is presented on a moving surface which intersects each point within a three dimensional space to allow the display of a 3D image.
Abstract: A digitized video system utilizing a spatial light modulator which includes deformable mirror devices to form an image. The image is projected onto a moving surface which intersects each point within a three dimensional space to allow the display of a three dimensional image. Each mirror cell is capable of projecting an individual beam. The individual beams form one portion of an image.

221 citations


Patent
31 Oct 1991
TL;DR: In this article, a system consisting of a light source, a spatial light modulator, and appropriate optics for directing the light from the source to the spatial modulator and to the object to be scanned is described.
Abstract: A system for scanning objects is disclosed. The system consists of a light source, a spatial light modulator, and appropriate optics for directing the light from the source to the spatial light modulator and to the object to be scanned. Individual elements upon the modulator are activated to reflect those pixels' width of the light to the object. A detector is mounted such as to receive reflections from the object to be processed. The system can be hand-held, mounted into a counter, or used in other applications such as edge detector scanners.

167 citations


Journal ArticleDOI
TL;DR: A new two-dimensional optical architecture based on polarization switching by N spatial light modulators that provides 2(N) time delays to a phased-array antenna of p x p radiating elements is proposed and experimentally demonstrated.
Abstract: We propose and experimentally demonstrate a new two-dimensional optical architecture based on polarization switching by N spatial light modulators that provides 2N time delays to a phased-array antenna of p × p radiating elements. Moreover the 0 to 2π phase of the microwave signals is optically controlled by a liquid-crystal spatial light modulator that operates in the birefringent mode. The microwave signal originates from the coherent detection of a dual-frequency laser beam obtained with an acousto-optic frequency shifter. Preliminary experimental results obtained at a microwave frequency f = 1.85 GHz are presented.

100 citations


Journal ArticleDOI
TL;DR: In this article, a real-time construction and reconstruction of Fresnel holograms is demonstrated using an optically addressable ferroelectric liquid-crystal spatial light modulator with a resolution up to 175 line pairs/mm.
Abstract: Real‐time construction and reconstruction of Fresnel holograms is demonstrated using an optically‐addressable ferroelectric liquid‐crystal spatial light modulator with a resolution up to 175 line pairs/mm. A bright holographic image is read out due to the optical separation between the write and read sides by a dielectric mirror.

94 citations


Patent
12 Dec 1991
TL;DR: In this article, a processless phototool generator uses a pulsed excimer laser to image a deformable mirror spatial light modulator onto a thin ablateable coating on a quartz substrate.
Abstract: A processless phototool generator uses a pulsed excimer laser to image a deformable mirror spatial light modulator onto a thin ablateable coating on a quartz substrate. The light pulse ablates and clears the coating from selected areas according to the data pattern in the deformable mirror array. Exposure uniformity is enhanced by a two dimensional overwriting method. The high image reduction ratio enables high power densities on the substrate without exceeding the permissible power density on the deformable mirror array. Since the recording is processless (i.e. no development required) the generated image can be verified immediately after writing. The last feature is of particular importance in phase-shift masks.

79 citations


Patent
28 Jun 1991
TL;DR: In this article, a structure for optical interconnection is disclosed along with methods of manufacture and operation, which consists of optical fibers connected to an array of microlenses, either through integrated waveguides or not, that direct light onto a mirror formed in a substrate, which reflects light to a spatial light modulator.
Abstract: A structure for optical interconnection is disclosed along with methods of manufacture and operation. In one embodiment, the structure consists of optical fibers connected to an array of microlenses, either through integrated waveguides or not, that direct light onto a mirror formed in a substrate, which reflects light to a spatial light modulator. The spatial light modulator in turn reflects the light back to another mirror, which reflects the light through another microlens array, through integrated waveguides or not, and out another optical fiber. The structure is manufactured by forming the mirrors out of the substrate, forming waveguides if desired, forming troughs for the fibers and the microlenses, attaching external pieces such as the fibers, the lenses, and the spatial light modulator package, and packaging the device to maintain alignment.

Proceedings ArticleDOI
TL;DR: In this article, the authors describe three fundamental methods for attaining full complex modulation. And the mathematics for two of these methods are presented, and signal decomposition in their terms is outlined.
Abstract: Although the action of a spatial light modulator (SLM) is usually restricted to certain locations on the operating curve of the complex plane, NASA is planning to use architectures that allow two continuously variable SLMs to function jointly so as to access the full interior of a closed curve in the complex plane. This paper describes three fundamental methods for attaining full complex modulation. The mathematics for two of these methods is presented, and signal decomposition in their terms is outlined.

Journal ArticleDOI
TL;DR: The theoretical results based on this model match the experimental measurements and allow us to optimize the operation of the LCLV as an intensity or phase-only spatial light modulator.
Abstract: The complex amplitude reflectance of the liquid crystal light valve (LCLV) is determined as a function of the writing intensity and applied voltage using an approximate model. The input and output polarizers are assumed to have arbitrary directions. The theoretical results based on this model match our experimental measurements. This theory allows us to optimize the operation of the LCLV as an intensity or phase-only spatial light modulator. When the polarizers are orthogonal and the input polarizer is at -34 degrees with the front liquid crystal director, the intensity reflectance reaches 100% (compared to 81% for the conventional configuration). Phase-only modulation is realizable by use of appropriate applied voltage bias and configuration of polarizers.

Journal ArticleDOI
TL;DR: Correlation experiments for the images used in the proposed setup indicate that nonlinear compression of the joint power spectrum may be necessary to produce good correlation performance and a peak-to-sidelobe ratio of larger than unity.
Abstract: Correlation experiments for the images used in the proposed setup indicate that nonlinear compression of the joint power spectrum may be necessary to produce good correlation performance and a peak-to-sidelobe ratio of larger than unity.

Patent
19 Jul 1991
TL;DR: A light writing type projection display for inputting two-dimensional information such as images or data patterns into a spatial light modulator, and displaying the information on a screen by using a display light beam was proposed in this article.
Abstract: A light writing type projection display for inputting two-dimensional information such as images or data patterns into a spatial light modulator by using a write light beam, and displaying the information on a screen by using a display light beam. The projection display comprises a light write type spatial light modulator, and either a cathode ray tube or a liquid crystal television set. The modulator includes an antireflection film, a glass substrate, a transparent electrode, a liquid crystal composition, a dielectric mirror, a light absorption layer, a photoconductive layer, a transparent electrode and a fiber optic plate which are laminated in the recited sequence. The liquid crystal composition includes one of a nematic liquid crystals, cholesteric liquid crystals, and smectic liquid crystals combined with a resin matrix. The resin matrix has a refractive index equal to or approximately equal to the ordinary or extraordinary refractive index of the liquid crystals, or equal to or approximately equal to the refractive index of the randomly oriented liquid crystals. The liquid crystals are enclosed and scattered in the resin matrix, or the resin matrix is enclosed and scattered in the liquid crystals. The projected light beam is thrown on a screen by using a display beam light source and the projection optical system. Compared with the conventional displays, the display is superior in brightness, contrast ratio, spatial uniformity of the display image and response time. Analog motion images can be displayed by using a schlieren optical system.

Patent
18 Dec 1991
TL;DR: In this paper, an optical system is described for combining separate deformable mirror device images into a single image, which is particularly useful for presenting spatial light modulator images to the printing drum of a xerographic process for letter quality documents.
Abstract: An optical system is described for combining separate deformable mirror device images into a single image. The resulting image is a single continuous image comprising left and right halves corresponding to the original individual images. The system is particularly useful for presenting spatial light modulator images to the printing drum of a xerographic process for letter quality documents. The combined image width allows a substantially greater printing width than was previously possible.

Patent
29 Jul 1991
TL;DR: In this paper, a photo-refractive 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 transmittivities variation for minimum variation in the refractive index or optical path length.
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.

01 Jan 1991
TL;DR: In this paper, the development of a ferroelectric liquid-crystal-over-singlecrystal silicon spatial light modulator (SLM) was described, with an array of 176 X 176 pixels over a clear aperture of 5.28 mm.
Abstract: The development of a ferroelectric liquid-crystal-over-single-crystal-silicon spatial light modulator is described. The reflective SLM has an array of 176 X 176 pixels over a clear aperture of 5.28 mm X 5.28 mm. Prototype devices driven from a specially designed high speed frame store have been operated at frame rates of approximately equals 1 kHz.

Patent
06 Aug 1991
TL;DR: In this article, a spatial light modulator is used to address encode the beam by modulating the beam in the space domain and the resulting data and address modulated beam possesses the property of orthogonality.
Abstract: In a fiber optic communication system, an acoustooptic modulator operates to provide a coherent light beam that is data encoded in the beam's time domain, for example by intensity modulation of the beam. A spatial light modulator then operates to address encode the beam by modulating the beam in the space domain. The resulting data and address modulated beam possesses the property of orthogonality. This beam is now transmitted to the input of a multimode optical fiber. The speckle pattern that exits the output of the optical fiber also exhibits orthogonality. This output beam is presented to a beam splitter in order to produce two spatially modulated speckle light patterns therefrom. These two beams are then focused onto photorefractive means whereat a hologram is produced. This hologram operates to address decode the beam output of the optical fiber. Detector means now operates to detect the data by receiving the beam as it is diffracted by the hologram. Ring and star interconnect networks are described.

Patent
02 Aug 1991
TL;DR: In this article, an image projector in which a spatial modulation of light is carried out on the two orthogonal components of polarization of light in order to increase the luminous efficiency of the projector is described.
Abstract: Disclosed is an image projector in which a spatial modulation of light is carried out on the two orthogonal components of polarization of light in order to increase the luminous efficiency of the projector. The image projector of the invention includes a light source, a projection screen, a splitter of polarizations splitting the light into two polarized beams having complementary polarizations, two mirrors reflecting the two polarized beams, firstly so as to give them opposite directions and superimpose them on one and the same axis on which a spatial light modulator is positioned and, secondly, to make them pass again through the polarization splitter by which they are superimposed on one and the same axis with one and the same direction and oriented towards the projection screen and/or the light source as a function of their modulation by the spatial modulator.

Journal ArticleDOI
R. Mark Boysel1
TL;DR: In this article, the authors describe the design, fabrication, and performance of the frame-addressed spatial light modulator (FASLM), a frame-updated 128 x 128 deformable mirror device (DMD) spatial modulator(SLM) consisting of a 128 × 128 array of mirror elements addressed by an underlying virtual phase CCD array.
Abstract: We describe the design, fabrication, and performance of the frame-addressed spatial light modulator (FASLM), a frame-updated 128 x 128 deformable mirror device (DMD) spatial light modulator(SLM). This new DMD consists of a 128 x 128 array of mirror elements addressed by an underlying virtual phase CCD array. Each mirror element consists of four cantilever beam mirrors attached to a central pillar, allowing contiguous placement of the elements. The FASLM operates at higher speed (up to 4-kHz frame rate with 100% pixel addressing) and with a higher optical duty cycle (96%) than previous DMD SLMs.

Journal ArticleDOI
TL;DR: The operating characteristics of a 64 x 64 array electrically addressed spatial light modulator that uses a dynamic memory on a very-large-scale-integration chip and a ferroelectric liquid-crystal modulator are discussed.
Abstract: The operating characteristics of a 64 × 64 array electrically addressed spatial light modulator that uses a dynamic memory on a very-large-scale-integration chip and a ferroelectric liquid-crystal modulator are discussed.

Patent
13 Sep 1991
TL;DR: In this paper, an information recording apparatus includes an acoustooptic deflector, which receives a laser beam from a recording light source and an amplitude modulation signal, and diffracts the laser beam in two directions.
Abstract: An information recording apparatus includes an acoustooptic deflector (14), receives a laser beam from a recording light source (1) and an amplitude modulation signal, and diffracts the laser beam in two directions, thereby generating a carrier wave diffracted beam and a lower sideband diffracted beam The carrier wave diffracted beam is provided with information by a spatial light modulator (4) and modulated, and is incident, as a signal beam, on a moving recording medium (5) The lower sideband diffracted beam is incident, as a reference beam, on the same incident region as that of the signal beam The two beams interfere with each other, and multiplexed recording of a hologram is performed on the recording medium (5)

Patent
18 Nov 1991
TL;DR: In this article, a spatial light modulator of the so-called deformable mirror device (DMD) type has an array of individual mirror elements (20) arranged in lines.
Abstract: A spatial light modulator of the so-called deformable mirror device (DMD) type has an array of individual mirror elements (20) arranged in lines. The elements are individually driven to change their orientations. Portions (30) of the mirror elements are non-reflecting such as to divide the mirror elements into substantially equal portions forming a greater number of lines of narrower width, with a view to reducing the subjectively visible line structuring.

Patent
13 Nov 1991
TL;DR: In this paper, a spatial light modulator comprises a plate of non-ferroelectric PLZT ceramic, which is formed by depositing a reflecting coating in the desired array on one side of the plate.
Abstract: A spatial light modulator comprises a plate of non-ferroelectric PLZT ceramic. An array of pixels is formed by depositing a reflecting coating in the desired array on one side of the plate. A longitudinal electric field is applied so that the light entering the plate from the side opposite the reflecting coating experiences a polarization-independent refractive index change when the electric field is applied as it propagates parallel to the electric field. The required voltages may be decreased when a partially reflecting coating is deposited on the side opposite the reflecting coating. Grooves in the plate effectively isolate the pixels from electrical and mechanical crosstalk.

Journal ArticleDOI
TL;DR: A real-time holographic technique employing an optically addressed spatial light modulator was used to correct an incoherently illuminated image that had made a single pass through an aberrator.
Abstract: A real-time holographic technique employing an optically addressed spatial light modulator was used to correct an incoherently illuminated image that had made a single pass through an aberrator. Aberrations that change slowly compared with the integration time of the spatial light modulator are fully corrected.

Journal ArticleDOI
TL;DR: An optical implementation of a single-layer, second-order neural network is presented and the machine successfully associates eight randomly chosen pattern-target pairs and can learn the parity association.
Abstract: An optical implementation of a single-layer, second-order neural network is presented. The quadratic products are obtained by passing the optical beam twice through the input ferroelectric liquid-crystal (FLC) spatial light modulator (SLM), with the interconnection weights being implemented by a further two-dimensional 128 × 128 FLC SLM. The machine successfully associates eight randomly chosen pattern–target pairs (dimensions 16 and 4, respectively) and can learn the parity association. Translation invariance is also demonstrated. Results from a computer model indicate that input SLM contrast ratios of 4:1 and electronic noise of 10% of the maximum output can be tolerated.

Patent
04 Jan 1991
TL;DR: In this article, a matrix-addressable field emitter array was used to supply a controlled electron emission to a two-dimensional signal processor element that may be either a processor of electrical or optical signals.
Abstract: The disclosed optical signal processor includes a matrix-addressable field emitter array for supplying a controlled electron emission to a two-dimensional signal processor element that may be either a processor of electrical or two-dimensional optical signals.

Journal ArticleDOI
TL;DR: In this article, a joint transform correlator that uses a phase-only spatial light modulator to input joint transform plane intensity data into the second Fourier transform system is presented, which produces signals that differ from, but are related to, the mathematical correlation between the test and reference input images.
Abstract: A theoretical analysis of a joint transform correlator that uses a phase-only spatial light modulator to input joint transform plane intensity data into the second Fourier transform system is presented. It is shown that this correlator produces signals that differ from, but are related to, the mathematical correlation between the test and reference input images. An undesirable characteristic of the correlator is that the form of the output signals depends on both the intensity-to-phase transfer characteristic of the phase modulator and the intensities of the input images. However, apodization of the joint transform intensity distribution by the reciprocal of the intensity distribution of the reference image Fourier transform can overcome this problem, and results in a correlator with narrow matching output peaks and high discrimination, in which the autocorrelation peak can be eliminated. Theoretical results are demonstrated by computer simulation.

Patent
23 Aug 1991
TL;DR: In this article, first and second speckle patterns representing the object before and after its deformation are written by double writing into a ferroelectric liquid crystal spatial light modulator (FLC-SLM).
Abstract: An object is typically illuminated by laser light, and reflected light carrying a speckle pattern is amplified by an image intensifier. First and second speckle patterns representing the object before and after its deformation, respectively are written by double writing into a ferroelectric liquid crystal spatial light modulator (FLC-SLM). The double-written image is read out from the FLC-SLM, and converted by a Fourier transform optical system into an output optical image, i.e., Young's fringe. The output optical image is detected by a photoelectric converter, and analyzed by an image processing device to determine a deformation of the object.