Showing papers on "Spatial light modulator published in 1996"

Reflective spatial light modulator with encapsulated micro-mechanical elements

Abstract: A spatial light modulator, comprised of an upper and a lower substrate. One or more electrostatically deflectable mirrors are suspended by torsion hinges from an optically transmissive upper substrate. The upper substrate is held above the lower substrate containing electronic circuitry. In operation, individual mirrors are selectively deflected and serve to spatially modulate light that is incident to, and then reflected back through, the upper substrate. An aperture layer is built into the upper substrate to enable light to reach only the flat mirror surfaces.

Spatial light modulator and directional display

Abstract: A liquid crystal spatial light modulator comprises columns and rows of picture elements (24-26). The columns are arranged as groups of columns, for instance under respective parallax generating elements in an autostereoscopic 3D display. The picture elements (24-26) are arranged as sets to form colour picture elements such that the picture elements (24-26) of each set are disposed at the apices of a polygon, such as a triangle (21), and are disposed in corresponding columns of the groups of columns.

Seamless, maskless lithography system using spatial light modulator

Abstract: The invention is a seamless, projection lithography system that eliminates the need for masks through the use of a programmable Spatial Light Modulator (SLM) with high parallel processing power. Illuminating the SLM with a radiation source (1) provides a patterning image of many pixels via a projection system (4) onto a substrate (5). The preferred SLM is a Deformable Micromirror Device (3) for reflective pixel selection using a synchronized pulse laser. An alternative SLM is a Liquid Crystal Light Valve (LCLV) (45) for pass-through pixel selection. Electronic programming enables pixel selection control for error correction of faulty pixel elements. Pixel selection control also provides for negative and positive imaging and for complementary overlapping polygon development for seamless uniform dosage. The invention provides seamless scanning motion by complementary overlap to equalize radiation dosage, to expose a pattern on a large area substrate (5). The invention is suitable for rapid prototyping, flexible manufacturing, and even mask making.

Encrypted holographic data storage based on orthogonal phase code multiplexing

Abstract: An encryption method and apparatus for holographic data storage are disclosed. In a system using orthogonal phase-code multiplexing, data is encrypted by modulating the reference beam using an encryption key K represented by a unitary operator. In practice, the encryption key K corresponds to a diffuser or other phase-modulating element placed in the reference beam path, or to shuffling the correspondence between the codes of an orthogonal phase function and the corresponding pixels of a phase spatial light modulator. Because of the lack of Bragg selectivity in the vertical direction, the phase functions used for phase-code multiplexing are preferably one dimensional. Such phase functions can be one-dimensional Walsh functions. The encryption method preserves the orthogonality of reference beams, and thus does not lead to a degradation in crosstalk performance.

Image projection system

Abstract: An image projection device having a spatial light modulator and a polarized source system for illuminating the spatial light modulator such that light of a first polarization state illuminates one region of the spatial light modulator and light of a second polarization state illuminates another region of the spatial light modulator. Preferably, the image projection device includes a first set of polarization selective light processing elements, including a first conicoid element which passes light of the first polarization state and reflects light of the second polarization state and a second set of polarization selective light processing elements including a second conicoid element which passes light of the second polarization state and reflects light of the first polarization state.

Laser printer using a fly's eye integrator

Abstract: A laser printer (10) is comprised of a laser diode array (11), a cross array illumination optics (21), a laser lenslet array (24), a spatial light modulator (40), and a fly's eye integrator (23) which illuminates the spatial light modulator with flooded uniform light. In another embodiment the angular spectrum of the light incident to the spatial light modulator is tailored to enhance the quality of modulation. The spatial light modulator (40), is illuminated uniformly by laser diode emitters (12) comprising laser diode array (11), and the spatial light modulator (40) break up the light into image elements, which are subsequently imaged to a media plane (60), to form a desired pattern of spots.

Reflective spatial light modulator array

Abstract: A reflective spatial light modulator array is described incorporating liquid crystal devices, mirrors, a semiconductor substrate, electrical circuits, and a reflector/absorber layer for blocking light. The invention overcomes the problem of shielding light from semiconductor devices, high optical throughput and contrast, pixel storage capacitance to hold the voltage across the liquid crystal device and precise control of the liquid crystal device thickness without spacers obscuring the mirrors.

Projection-display apparatus and method providing improved brightness of projected color image

Abstract: Methods and apparatus are disclose for obtaining a bright projected color image. In a representative apparatus, polarized beam splitters (one for each primary color of an image to be projected) separate p-polarized light and s-polarized light for each of the primary colors. Each separated s- and p-polarized light for each color enters a respective spatial light modulator. For each primary color, modulated light fluxes produced by the two spatial light modulators, which perform modulation of the same image, are analyzed and integrated by the polarized beam splitters. The analyzed and integrated light fluxes for each primary color are color integrated, either by projection using separate projection lenses for each color, or by a cross-dichroic prism followed by projection using a single lens.

Intensity and phase measurements of nondiffracting beams generated with a magneto-optic spatial light modulator.

Abstract: Nondiffracting beams are of interest for optical metrology applications because the size of the beam does not change as the beam propagates. However, accuracy can be increased if the diameter of the beam is smaller. One technique for accomplishing this is to use the dark axial intensity profile associated with a higher-order nondiffracting Bessel function beam. We generate these higher-order Bessel function beams with a programmable spatial light modulator. We study the intensity patterns and the phase dependence of these nondiffracting beams. In addition, we examine interference effects caused by recording these patterns onto a binary spatial light modulator.

Nondiffracting interference patterns generated with programmable spatial light modulators

Abstract: Nondiffracting beams are of interest for optical metrology applications because the size and shape of the beams do not change as the beams propagate. We have created a generating pattern consisting of a linear combination of two nondiffracting patterns. This pattern forms a nondiffracting interference pattern that appears as a circular array of nondiffracting spots. More complicated multiplexed arrays are also constructed that simultaneously yield two different nondiffracting patterns. We generate these Bessel function arrays with a programmable spatial light modulator. Such arrays would be useful for angular alignment and for optical interconnection applications.

Spatial light modulator with superstructure light shield

Abstract: A high contrast spatial light modulator (40) formed of micro-mechanical pixels (10). The supporting superstructure comprising the posts (12) and hinges (16) of the pixels (10) are shielded by an umbrella-like elevated light shield (42) extending over the hinge and posts. These light shields (42) are generally square in shape, and have edges arranged at approximately 45° with respect to the incident light to minimize diffraction of light therefrom into projection optics. The upper surfaces of the shields may be anodized to achieve a non-reflective, black surface when viewed through darkfield optics. The shields (42) are fabricated using conventional semiconductor processes, which are a natural extension of the baseline process.

Color spatial light modulator and color printer using the same

Abstract: A color spatial light modulator has red, green, and blue micromirror arrays juxtaposed in parallel. Each micromirror array has a number of micromirrors each formed with a filter for reflecting specific color light. As data "1" is written to a memory cell of an SRAM, the micromirror tilts by +θ and enters a valid reflection state in which spot light is utilized. As data "0" is written, the micromirror tilts by -θ and enters an invalid reflection state in which spot light is not utilized. A data write control circuit converts image data into mirror drive data and writes it to SRAM. Three-color parallel line light beams generated by the three-color micromirror arrays are projected by a projector lent onto color paper. A three-color image is printed line sequentially on the color paper.

Multisource infrared spectrometer

Abstract: A spectrometer having a source of broad band infrared energy, a relay mirror that focuses the infrared energy at an intercepting mirror, a first object mirror that collimates the infrared energy from the intercepting mirror, a spatial light modulator that receives the collimated infrared energy and reflects it back to the first object mirror, the spatial light modulator including deformable mirror elements, and a controller that deforms the mirror elements according to a predetermined pattern. Deformable mirror elements obtain needed spectra while reducing the mechanical complexity of the spectrometer.

Bit-splitting for pulse width modulated spatial light modulator

Abstract: A method of implementing pulse-width modulation in a display system (10, 20) that uses a spatial light modulator (SLM) (15) Each frame of data is divided into bit-planes, each bit-plane having one bit of data for each pixel of the SLM and representing a bit weight of the intensity value to be displayed by the pixels. Each bit-plane has a display time corresponding to a portion of the frame period, with bit-planes of more significant bits having longer portions. Then, the display times for one or more of the more significant bits are segmented so that the data for those bits can be displayed in segments rather than for a continuous time. (FIG. 3A). The segments are distributed throughout the frame period to reduce visual artifacts. (FIG. 3B).

Large arrays of spatial light modulators hybridized to silicon integrated circuits.

Abstract: Large, high-frame-rate spatial light modulators are key components required for the realization of real-time optical processors. We report a 128 × 128 array of GaAs-based optical modulators that we hybridized to a Si integrated circuit by using In bump bonds to form a spatial light modulator. These optical modulators are composed of a series of quantum wells within an asymmetric Fabry–Perot cavity to control the optical properties. The resulting 128 × 128 element array operates in an intensity-only reflection mode at greater than 100,000 frames per second. This array interfaces to a 486-based personal computer through a standard industry standard architecture bus.

Method and apparatus of aligning color modulation data to color wheel filter segments

Abstract: A method and apparatus (10) of aligning color modulation data to color wheel filter segments (13) in a field sequential color spatial light modulator display system. A color wheel (12) having a plurality of colored segments (13) joined at spokes (14) is rotated before a narrow light beam (20). The colored light (22) is observed until light of a mixed color is detected, this light of mixed color corresponding to light of equal portions from the two segments adjacent the spoke. The time between a wheel marker (42) is detected and when the predetermined mixed color is observed is measured. Optical sensors (50) can be utilized to sense a mixed color, such as magenta derived from the combination of a red/blue transition, but also can be done manually by briefly illuminating the wheel to visually ascertain this predetermined color. By calibrating the display system to know precisely where the spokes (14) are, referenced in time to when a wheel marker (42) is detected, colored modulation data for each colored segment is only fed to the SLM (26) during the time the corresponding color filter is in the light path.

Characterization of a liquid crystal television as a programmable spatial light modulator

Abstract: The properties of a liquid crystal television to be used as a spatial modulator of the polarization of a laser beam are studied. It is found that the model most commonly used for the display description does not adequately reproduce the transmission through crossed polarizers. A new model is proposed that takes into account additional birefringence effects resulting from border effects near the television windows. With this correction, the anomalous behavior of the television is explained and the throughput for different configurations is properly predicted.

Divided reset for addressing spatial light modulator

Abstract: A method of implementing pulse-width modulation in a display system ( 10, 20 ) that uses a spatial light modulator (SLM) ( 15 ). Each frame of data is divided into bit-planes, each bit-plane having one bit of data for each display element of the SLM and representing a bit weight of the intensity value to be displayed by the display elements. Each bit-plane has a display time corresponding to a portion of the frame period, with bit-planes of more significant bits having longer portions. The SLM is divided into reset groups connected to different reset lines ( 34 ), so that one reset group can be loaded and its display time begun while the next reset group is loaded. (FIG. 3 ). Short bit-planes are possible because the display time need not include the time to load the entire array, and for any reset group, its reset can be delayed while other reset groups are loaded.

Particle detection method and apparatus

Abstract: An apparatus and method for detecting particles on a surface of a semiconductor wafer having repetitive patterns includes a laser for illuminating an area on the front surface at grazing angle of incidence with a beam of polarized light. A lens collects light scattered from the area and forms a Fourier diffraction pattern of the area illuminated. A Fourier mask blocks out light collected by the lens at locations in the Fourier diffraction pattern where the intensity is above a predetermined level indicative of background information and leaves in light at locations where the intensity is below the threshold level indicative of possible particle information. The Fourier mask includes an optically addressable spatial light modulator and a polarization discriminator. A camera detects scattered light collected from the area by the lens and not blocked out by the Fourier mask.

Optical encryption interface

Abstract: An analog optical encryption system based on phase scrambling of two-dimensional optical images and holographic transformation for achieving large encryption keys and high encryption speed. An enciphering interface uses a spatial light modulator for converting a digital data stream into a two dimensional optical image. The optical image is further transformed into a hologram with a random phase distribution. The hologram is converted into digital form for transmission over a shared information channel. A respective deciphering interface at a receiver reverses the encrypting process by using a phase conjugate reconstruction of the phase scrambled hologram.

Compact architecture for holographic systems

Abstract: The holographic memory system we describe here integrates the various system components very closely to the crystal by using a smart pixel array and making use of phase-conjugate read-out to eliminate the need for imaging optics. This significantly reduces the alignment requirements and the number of required components. Our angularly multiplexed integrated read/write memory system is shown. An optoelectronic integrated circuit (OEIC) performing the functions of a spatial light modulator and a detector array is attached to the face of a 900-geometry photorefractive crystal perpendicular to the axis of the signal beam, while liquid crystal beam steerers are attached to the two adjacent faces that intersect the reference beam (the beam steerer behind the crystal is not visible in the figure). These beam steerers address the angularly multiplexed memory. Holograms are recorded by signal beam interference.

Illumination optics for spatial light modulator

Abstract: Variations on the Koehler illumination system, used for providing light to be reflected from, or transmitted by, an SLM. An anamorphic illumination system (10) uses multiple light sources (11) and a cylindrical lens (14) to provide an elongated and compressed beam to the SLM (16). A cascaded illumination system (30) uses multiple light sources (31) and multiple TIR prisms (33) to provide an extended light beam or one that is more intense, to the SLM (36).

Illumination system for hard copy apparatus

Abstract: An illumination system (10,30,100,130,150,180,200) for hard copy applications including an elongated array (32) of light emitting elements (34) in combination with a light mixing element (42,46) for mixing the light from the individual elements in the lateral or cross-process direction. A curved array (32) or linear array (102) of light emitting elements with an aspheric lens (108) may be utilized, with a cylindrical lens (36,106) compressing the beam of light in the vertical or process direction. The light mixing elements (42,46) are preferably comprised of holographic diffusers. Sufficient mixing of the light from the array is achieved in the cross-process direction whereby a reduction in light output of one light emitting element does not generate a significant localized reduction in intensity at the elongated spatial light modulator. Preferably, the spatial light modulator is a digital micromirror device (DMD), but may also comprise of other devices including those of the transmissive type, including liquid crystal devices.

Digitally tunable wavelength filter and laser

Abstract: A novel nonmechanical, digitally tunable, polarization insensitive and optically transparent wavelength filter using holograms electro-optically written on a ferroelectric liquid crystal (FLC) spatial light modulator (SLM) has been constructed and operated to tune to discrete wavelengths spaced by 1.3 nm. The filter has been incorporated in a ring laser which is tunable over a range of 38.5 nm across the erbium window, giving output powers of 10 mW. Both wavelength filter and tunable laser are suitable for wavelength division multiplexing (WDM) applications.

Spatial light modulator with improved peak white performance

Abstract: A spatial light modulator based imaging system (30) with improved peak white performance characteristics. The apparent dynamic range of the spatial light modulator (74) is increased by adding light to pixels neighboring a saturated pixel. An apparent bloom effect is created with the pixels neighboring the saturated pixel appearing brighter, to give sunlight reflecting from the surface of a lake, for instance, more sparkle or highlights. Charts or equations are utilized to determine the degree to which pixel brightness is increased for neighboring pixels. The closer a pixel to a saturated pixel, and the greater the saturation of a particular pixel, the greater increase in brightness for neighboring pixels.

Liquid crystal projector using a spatial light modulator and two rotating color filters

Abstract: A liquid crystal display apparatus which includes: a light-addressed liquid crystal light valve including a photoconductive layer and a liquid crystal layer between a pair of light transmitting substrates, each of the light transmitting substrates having an electrode for applying a voltage across the photoconductive layer and the liquid crystal layer; a writing unit for writing an image of a display medium in the light-addressed liquid crystal light valve with writing light from the display medium through a writing lens; a projecting unit for projecting the image written in the light-addressed liquid crystal light valve by irradiating reading light from a projection light source to the light-addressed liquid crystal light valve; and a controlling unit for controlling at least one of operational characteristics of the light-addressed liquid crystal light valve and a luminance of the writing light in accordance with a luminance of the display medium, is disclosed.

Light amplitude modulation with neutral density filters

Abstract: A system and method for increasing the number of bits available for use in a video display system that includes at least one spatial light modulator. The system uses a wheel (30) of three colors, or a color wheel that is clear, including at least one segment (34) which has a lower intensity region, referred to as a neutral density filter. Alternately, the filter could be a liquid crystal controller to control either light amplitude or color. By using a lower intensity region, the amount of time available to process the least significant bit of the data sample is lengthened, thereby eliminating the constraint on the number of bits available for display.

Experimental comparison of binary joint transform correlators used for fingerprint identification

Abstract: We compare the experimental performance of 12 variations of the binary joint transform correlator (BJTC) when used for fingerprint identification. Three hardware architectures were used: a single spatial light modulator (SLM) BJTC, a BJTC using two input SLMs, and a chirpencoded BJTC using two input SLMs. These correlators were implemented on the same hardware setup with minor modifications. With each hardware configuration, four binarization techniques were implemented: global threshold, Fourier plane windowing, frame subtraction, and frame subtraction followed by windowing. A set of 10 experiments was used to characterize the output peak intensity, peak-to-noise ratio, and discrimination ratio. The same set of experiments was run on each of the 12 correlator variants.

Optoelectronic parallel computing system with reconfigurable optical interconnection

Abstract: System architectures for optoelectronic parallel computing system are reviewed and a massively parallel processing system with a reconfigurable optical interconnection among electronic general purpose processing elements (PE’s) is described as an example. If PE is so compact, more than 4,000 PE’s can be integrated into one chip for directly coupling with array type optical devices in parallel. The optical interconnection is constructed using a surface emitting laser diode array and a phase modulation type spatial light modulator on which optimized computer generated holograms are written. In this paper, the design concept of optoelectronic parallel computing systems and PE’s, configurations of experimental system, and algorithms for parallel optoelectronic computing system are shown.