Showing papers on "Spatial light modulator published in 1999"

Encoding amplitude information onto phase-only filters

Abstract: We report a new, to our knowledge, technique for encoding amplitude information onto a phase-only filter with a single liquid-crystal spatial light modulator. In our approach we spatially modulate the phase that is encoded onto the filter and, consequently, spatially modify the diffraction efficiency of the filter. Light that is not diffracted into the first order is sent into the zero order, effectively allowing for amplitude modulation of either the first-order or the zero-order diffracted light. This technique has several applications in both optical pattern recognition and image processing, including amplitude modulation and inverse filters. Experimental results are included for the new technique.

Spatial light modulator having improved contrast ratio

Abstract: A spatial light modulator (70) comprised of an array of micromirrors (72) each having support post (74) The support post (74) defines support post edges (76) in the upper surface of the mirrors (72) These support post edges (76) are all oriented at 45 degree angles with respect to an incident beam of light from a light source (80) to minimize diffraction of light from the edges (76) into the darkfield optics when the mirrors are oriented in the off-state The present invention achieves an increased contrast ratio of about 20% over conventional designs

An optical sectioning programmable array microscope implemented with a digital micromirror device.

Abstract: The defining feature of a programmable array microscope (PAM) is the presence of a spatial light modulator in the image plane. A spatial light modulator used singly or as a matched pair for both illumination and detection can be used to generate an optical section. Under most conditions, the basic optical properties of an optically sectioning PAM are similar to those of rotating Nipkow discs. The method of pattern generation, however, is fundamentally different and allows arbitrary illumination patterns to be generated under programmable control, and sectioning strategies to be changed rapidly in response to specific experimental conditions. We report the features of a PAM incorporating a digital micromirror device, including the axial sectioning response to fluorescent thin films and the imaging of biological specimens. Three axial sectioning strategies were compared: line scans, dot lattice scans and pseudo-random sequence scans. The three strategies varied widely in light throughput, sectioning strength and robustness when used on real biological samples. The axial response to thin fluorescent films demonstrated a consistent decrease in the full width at half maximum (FWHM), accompanied by an increase in offset, as the unit cells defining the patterns grew smaller. Experimental axial response curves represent the sum of the response from a given point of illumination and cross-talk from neighbouring points. Cross-talk is minimized in the plane of best focus and when measured together with the single point response produces a decrease in FWHM. In patterns having constant throughput, there appears to be tradeoff between the FWHM and the size of the offset. The PAM was compared to a confocal laser scanning microscope using biological samples. The PAM demonstrated higher signal levels and dynamic range despite a shorter acquisition time. It also revealed more structures in x-z sections and less intensity drop-off with scanning depth.

High Efficiency Electrically-Addressable Phase-Only Spatial Light Modulator

Abstract: To realize a high efficiency electrically addressable phase-only modulator, we have coupled a liquid crystal display (LCD) to an optically addressed parallel-aligned nematic liquid crystal spatial light modulator (PAL-SLM) with a set of lenses. Phase modulation exceeding 3ϖ at 532 nm wavelength was obtained. We obtained linear transfer characteristics for phase modulation at various desired phase levels after calibration and adjustment of the transfer characteristics of the PAL-SLM and the LCD. Diffraction efficiency of 40% for binary phase grating and of 90% for 8-level blazed phase grating, which were very close to the simulation values, were observed. The power loss of the readout light was caused when passed through a half mirror, therefore, we examined a setup using an oblique readout light at the modulator. Very high diffraction efficiency was obtained from the setup by optimizing the polarization direction and optical path for this light, and the orientation of liquid crystals. Since the modulator can perform at better than 90% diffraction efficiency and at nearly 100% reflectivity, various high efficiency systems utilizing such modulators are expected.

Mirrors on a chip

Abstract: The design, development, and performance of the digital micromirror device (DMD), a spatial light modulator for projection displays, are examined. The DMD covers each memory cell of a CMOS static RAM with a movable micromirror. Electrostatic forces contingent on the data in the cell tilt the mirror either on or off, modulating the light incident on its surface. Light reflected from any on-mirrors passes through a projection lens and creates images on a large screen. Light from the remaining off-mirrors is reflected away from the projection lens and trapped. The standard-resolution version of the DMD corresponds to the National Television System Committee (NTSC) or Phase Alternation Line (PAL) standard. It is a chip about 2.3 cm/sup 2/ covered by 442368 movable mirrors, each 16 mu m on a side. >

Reflective liquid crystal modulator based printing system

Abstract: An apparatus and method of printing two-dimensional swaths of area onto a photosensitive media uses at least one reflective liquid crystal spatial light modulator. In the apparatus and method, illumination optics receive light from a light source and image the light at a polarization beamsplitter element. The polarization beamsplitter element images one polarization state of light at the spatial light modulator to create an essentially telecentric illumination at the spatial light modulator.

Holographic recording using a digital micromirror device

Abstract: We describe the use of a digital micromirror device (Texas Instruments, Inc. ' s DMDTM) as a spatial light modulator forholographic applications. Questions of the interferometric effects of the moving mirror structure and the appropriateness ofpulse-width modulation for grayscale imaging are addressed. Compensation for the particular attributes of DMD imaginghas allowed the creation of full-color holographic stereograms of high image quality.Keywords: holography, spatial light modulator (SLM), digital micromirror device (DMD) 1. INTRODUCTION Spatial light modulators (SLMs) are key components of holographic stereogram printer systems. They are used to display the sequence of two-dimensional stereoscopic perspective views that are being holographically recorded. Because allinformation about the object scene is transduced by the SLM, it is a very important factor in the determination of the finalholographic image quality. Some SLMs typically used for holography include: positive transparency film (35

Packaged integrated processor and spatial light modulator

Abstract: An integrated circuit die may have a processor and a spatial light modulator formed in the same die. An opening may be provided in an interposer to allow light to reach the spatial light modulator. A plurality of bump bonds may space the interposer from the die region including the processor. Thus, a display may be formed in an integrated fashion with a processor.

Rapid prototyping apparatus and method of rapid prototyping

Abstract: The invention relates to a rapid prototyping apparatus for the manufacturing of three dimensional objects by additive treatment of cross sections comprising a wholly or partially light-sensitive material (2), said apparatus comprising at least one light source for illumination of a cross section of the light-sensitive material (2) by at least one spatial light modulator of individually controllable light modulators, wherein at least one light source is optically coupled with a plurality of light guides (8) arranged with respect to the spatial light modulator arrangement in such a manner that each light guide (8) illuminates a sub-area of the cross section According to the invention, it is possible to obtain a significant simplification of an RP design system, just as the apparatus designed are essentially capable of creating prototypes of any size, according to the invention

Nonmechanical Optical Manipulation of Microparticle Using Spatial Light Modulator

Abstract: A spatial light modulator (SLM) is introduced to an optical manipulation system. The real-time reconfigurable feature of the SLM makes it possible to perform an optical manipulation of microparticles without mechanical movements of optical parts. A liquid crystal SLM incorporated in the system forms a Fresnel zone plate (FZP). The beam spot generated by the FZP is imaged on a sample solution by reduction optics. A microparticle in the sample solution is trapped by the beam and manipulated by changing the addressing position of the FZP onto the SLM from a computer. The nonmechanical optical manipulation of microparticles is demonstrated for the first time.

Compositions and methods involving direct write optical lithography

Abstract: An improved optical photolithography system and method provides predetermined light patterns generated by a direct write system without the use of photomasks. The Direct Write System provides predetermined light patterns projected on the surface of a substrate (e.g., a wafer) by using a computer controlled means for dynamically generating the predetermined light pattern, e.g., a spatial light modulator. Image patterns are stored in a computer and through electronic control of the spatial light modulator directly illuminate the wafer to define a portion of the polymer array, rather than being defined by a pattern on a photomask. Thus, in the Direct Write System each pixel is illuminated with an optical beam of suitable intensity and the imaging (printing) of an individual feature is determined by computer control of the spatial light modulator at each photolithographic step without the use of a photomask. The Direct Write System including a spatial light modulator is particularly useful in the synthesis of DNA arrays and provides an efficient means for polymer array synthesis by using spatial light modulators to generate a predetermined light pattern that defines the image patterns of a polymer array to be deprotected.

Electronic color switching in field sequential video displays

Abstract: A sequential color display system using three spatial light modulators and dichroic filters to sequentially provide a primary color light beam to a projection spatial light modulator. A set of dichroic filters separates a white light beam into primary colored light beams. Each primary colored light beam is modulated by a spatial light modulator to selectively allow it to travel to a second set of dichroic filters. The second set of dichroic filters recombines the primary color light beams—only one of which is typically active at any given time—to form a sequential color light beam. A projection spatial light modulator selectively modulates the sequential color light beam to form a sequential color image projected onto an image plane.

17.3: Calibration of a Scanned Linear Grating Light Valve Projection System

Abstract: The Grating Light Valve (GLV ) technology has been used in an innovative system architecture to create a high resolution projected image by optically scanning a linear array of GLV pixels. We will discuss optical and electrical techniques used to optimize the performance of this unique architecture in terms of overall image quality, uniformity and repeatability. Introduction to the GLV Technology The Grating Light Valve technology is a means for creating a high-performance spatial light modulator on the surface of a silicon chip. It is based on simple optical principles that leverage the wavelike behavior of light, using diffractive interference as the basis for discriminating between on and off pixel states. A GLV array is fabricated using conventional CMOS materials and equipment, adopting techniques from the emerging field of Micro-Electromechanical Systems (MEMS). Pixels are comprised of a series of identical mechanical structures, fabricated using very few masks and processing steps. The end result is a unique combination of high performance, reliability, and low cost at production volumes.

Spectral Imaging in a Programmable Array Microscope by Hadamard Transform Fluorescence Spectroscopy

Abstract: We report the use of a thin-film transistor (TFT) twisted nematic liquid crystal spatial light modulator (SLM) for Hadamard transform two-dimensional spectral imaging in a fluorescence microscope. The liquid crystal SLM placed in the primary image plane of the microscope generates a set of spatial encoding masks defined by a cyclic S-matrix. The light passing through the mask is relayed by anamorphic optics to the entrance of an imaging spectrograph and detected with a charge-coupled device (CCD) camera. The SLM allows for the convenient generation of arbitrary masks without moving parts. The Hadamard transform approach transmits up to 50% of the light from the image field for multichannel detection, but is subject to transmission losses in the SLM. The system allows the convenient acquisition of two-dimensional spectral images. We characterized and tested many of the parameters controlling both spatial and spectral resolution, and demonstrated the system in the analysis of both naturally fluorescing and stained biological samples.

Image display system

Abstract: An image display system, e.g. for projection type displays, has an electrically addressed spatial light modulator or EASLM ( 1 ) and an optically addressed spatial light modulator or OASLM ( 5 ). An image formed on the EASLM ( 1 ) is transferred to a part of the OASLM ( 5 ) by an image transfer means ( 3 ) and the image produced by the OASLM ( 5 ) is formed from a plurality of successive images formed by the EASLM.

Heated ferroelectric liquid crystal spatial light modulator with improved contrast, improved grayscale resolution, and decreased pixel sticking when operated in a non-DC balanced mode

Abstract: A heated ferroelectric liquid crystal-based spatial light modulator (SLM) that minimizes pixel sticking when operated in a non-DC-balanced mode with spiking and method for using same. The SLM comprises a transparent electrode, a pixellated electrode, ferroelectric liquid crystal material, and a heater. The ferroelectric liquid crystal material is sandwiched between the transparent electrode and the pixellated electrode. The heater is capable of heating the ferroelectric material to at least 40° C. and preferably to between 50 and 60° C. The invention may also provide a temperature sensor for detecting the temperature of the SLM and a temperature control circuit that is electrically connected to both the temperature sensor and the heater. The temperature sensor may be a diode located proximate to the pixellated electrode or a photo-diode located remote from the spatial light modulator. The heater may be integrated into and encapsulated by a substrate supporting the pixellated electrode or it may be supported on a second major surface of the substrate. The method according to the invention includes providing a SLM, preheating the SLM, and operating the SLM in a non-DC-balanced mode with spiking while monitoring and maintaining the a temperature of the SLM above 50° C.

Methods involving direct write optical lithography

Abstract: An improved optical photolithography system and method provides predetemined light patterns generated by a direct write system without the use of photomasks. The Direct Write System provides predetermined light patterns projected on the surface of a substrate (e.g., a wafer) by using a computer controlled component for dynamically generating the predetermined light pattern, e.g., a spatial light modulator. Image patterns are store in computer and through electronic control of the spatial light modulator directly illuminate the wafer to define a portion of the polymer array, rather than being defined by a pattern on a photomask. Thus, in the Direct Write System each pixel is illuminated with an optical beam of suitable intensity and the imaging (printing) of an individual feature is determined by computer control of the spatial light modulator at each photolithographic step without the use of a photomask. The Direct Write System including a spatial light modulator is particularly useful in the synthesis of DNA arrays and provides an efficient element for polymer array synthesis by using spatial light modulators to generate a predetermined light pattern that defines the image patterns of a polymer array to be deprotected.

Method for creating three-dimensional objects by cross-sectional lithography

Abstract: An improved method for creating a three-dimensional object by generating a cross-sectional pattern of energy of an object to be formed at a selected surface of a medium capable of altering its physical state in response to the energy projected or transmitted onto the selected layer. By impinging radiation, particle bombardment, or chemical reaction by a method controlled by a spatial light modulator, successive adjacent cross-sections of the object are rapidly formed and integrated together to provide a step-wise laminar build-up of the desired object creating a three dimensional manifestation from bitmap images of a series of cross-sections of a computer generated model.

Spatial light modulator and spatial light modulating method

Abstract: When a signal image is transmitted from a transmission liquid crystal device (4) to an optically-addressed parallel-aligned liquid crystal spatial light modulator (6) by means of a write light beam, signal components resulting from the pixel structure of the transmission liquid crystal device (4) can be eliminated by giving the following conditions: 1/2P

Microfabrication by use of a spatial light modulator in the ultraviolet: experimental results.

Abstract: We report the development of a new microstereophotolithography technique for creation of three-dimensional microcomponents by use of a planar, layer-by-layer process of exposure, in which a spatial light modulator is used as a dynamic lithographic mask. The system operates in the UV to take advantage of the wide supply of commercially available photopolymers designed for conventional stereolithography. With this novel procedure it is possible to build components with feature sizes as small as a few micrometers. The experimental setup is briefly described, and the first microcomponent fabricated by this system is shown.

Design and fabrication of 10×10 micro-spatial light modulator array for phase and amplitude modulation

Abstract: In this paper, a 10×10 micro-spatial light modulator (micro-SLM) array for phase and amplitude modulation of incident light is designed and fabricated using surface micromachining technology. Hidden spring structure is used in order to maximize the fill-factor and minimize diffraction effect. A designed micro-SLM is composed of a mirror plate, upper electrodes, five support posts, and bottom electrodes. The spring structures are composed of four double crab leg springs for phase modulation (piston mode operation) and two torsional springs for amplitude modulation (tilt mode operation). The micro-SLM is actuated by electrostatic force generated between upper electrode and bottom electrode. In case of phase modulation, the maximum deflection length of mirror plate is designed to be 4 μm and in case of amplitude modulation, micro-SLM is designed to be capable of tilting ±5.4° to reflect incident light. The designed micro-SLM array is successfully fabricated with surface micromachining technology using thick photoresist as a sacrificial layer and aluminum as a structural material. Mirror plate and spring structure are fabricated without initial bending problem. The resulting fill-factor is about 91.7%. Static and dynamic characteristics of the fabricated micro-SLM in the case of amplitude modulation are measured with optical measurement system. In the fields of adaptive optics and pattern recognition system, SLM is used to modulate the phase and amplitude of incident light in order to correct aberration in an optical system through active control of mirror array.

Use of shutter to control the illumination period in a ferroelectric liquid crystal-based spatial light modulator display device

Abstract: A ferroelectric liquid crystal-based display device comprising a light source, a reflective spatial light modulator, a light output, a beam splitter, and a shutter. The beam splitter is located and aligned relative to the light source, the light output, and the spatial light modulator such that light generated by the light source is reflected or transmitted towards the spatial light modulator, and then light reflected by the spatial light modulator is reflected or transmitted towards the light output. The shutter has both and OPEN and a CLOSED state, and may include ferroelectric liquid crystal material. The shutter may be located and aligned relative to the lights source and the beam splitter such that when OPEN it transmits the light generated by the light source towards the beam splitter, and when CLOSED it prevents transmission of the light generated by the light source towards the beam splitter. Alternatively, the shutter may be located and aligned relative to the light output and the beam splitter such that when OPEN it transmits the light reflected by the spatial light modulator towards the light output, and when CLOSED it prevents transmission of the light reflected by the spatial light modulator towards the light output. A color separator and a first, second and third reflective spatial light modulators may be used in place of the above-described spatial light modulator. The color separator is located and aligned such that a first, second, and third wavelength band from the light generated by the light source, after being transmitted or reflected by the beam splitter, is transmitted or reflected towards the first, second, and third reflective spatial light modulators, respectively. Each of the first, second, and third reflective spatial light modulators include ferroelectric liquid crystal material.

Programmable axial apodizing and hyperresolving amplitude filters with a liquid-crystal spatial light modulator.

Abstract: Amplitude-transmitting filters for apodizing and hyperresolving applications can be easily implemented by use of a two-dimensional programmable liquid-crystal spatial light modulator operating in a transmission-only mode. Experimental results are in excellent agreement with theoretical predictions. This approach can permit the analysis of various filter designs and can allow the filters to be changed rapidly to modify the response of an optical system.

Projector for digital cinema

Abstract: A digital cinema projection system ( 200 ) for projecting images onto a display screen. The projection system ( 200 ) comprises a lamp console ( 102 ) and a projector ( 202 ). The projector ( 202 ) receives digital image data, processes the digital image data to create an image data stream that is compatible with the chosen spatial light modulator, and uses the processed image data to modulate a beam of light from the lamp console ( 102 ). A primary projection lens ( 204 ) and lens adapter mounted on a rotatable turret ( 206 ) focus the modulated light onto a display screen. Alternatively, an integrated anamorphic projection lens is used to eliminate the need for a separate lens adapter.

Display architectures using an electronically controlled optical retarder stack

Abstract: A system architecture for a display system with electronically controlled optical retarder stacks. The system uses only one spatial light modulator and a color filter to determine what the color of the image created by the modulator will be when projected onto a display surface. In one embodiment, the color filter passes one of red, green or blue light at any give time. The color filter can be placed between the light source and the modulator optics, between the modulator optics and the modulator, between the modulator and the projection optics, or made part of the projection optics itself. The retarder stack for transforming at least partially polarized input light can include a first retarder and a second retarder. The first retarder has a first retardance and a first orientation and the second retarder has a second retardance and a second orientation, both orientations with respect to the partially polarized light. The first retardance, first orientation, second retardance, and second orientation can be arranged to yield the desired polarization transformed light which includes a first spectrum and a second spectrum. The polarization of the first spectrum and the polarization of the second spectrum can be made orthogonal to each other. The polarizations can be linear or elliptical. If the polarization transformed light is linear, the directions of polarizations are different and in one case can be made perpendicular. If the polarization of the polarization transformed light is elliptical, then the polarizations are different and in on case can be made orthogonal in the general sense of orthogonality of polarization states.

Virtual image observation optical device

Abstract: PROBLEM TO BE SOLVED: To reduce noise in image data caused by stray light by setting an angle formed by respective surface normal vectors at a point where a luminous flux division element and a reflection element are crossed within a specified angle range while making a side where a light beam is reflected on the respective surfaces of the respective elements in the positive direction of vector. SOLUTION: A light source optical system is equipped with a 1st half mirror 21 being the luminous flux division element for deflecting light from a light source device for illumination 10 and guiding it to a reflection type spatial optical modulation element 20, and the reflection element 23 for guiding the light from a 2nd half mirror 22 being the luminous flux division element for deflecting the light from the light source optical system to the pupil 131 in observation space 130. An angle α formed by the 1st half mirror 21 and the reflection type spatial light modulator 20 is set to 45 deg. and the angle β formed by the surface normal vector drawn to the 2nd half mirror 22 and the surface normal vector drawn to the reflection element 23 is set to >=136 deg. and >=179 deg.. Thus, the noise in the image data caused by the stray light is reduced.

Implementation and characterization of a flexure-beam micromechanical spatial light modulator

Abstract: The phase-only spatial light modulator (SLM) is a highly efficient component for the filter plane of a real-time autocorrelator.'3 Texas Instruments has developed several SLMs using micromechanical mirror elements.4 The basic structure of the flexure-beam micromechanical element that we implement in this research is shown in Fig. 1 .Themirror element consists of a square reflecting plate attached at four points to L-shaped flexure hinges. The hinges are attached to four posts that provide the main mechanical support and electrical contact for the element. Each post also mechanically supports four hinges that attach to four different mirrors. The pixel is attracted downward by electrostatic force when it is addressed. The vertical motion of the mirror changes the length of the optical path at the pixel and hence the phase information. There are two approaches to building such a micromirror device: (1) addressing at the mirror through the post and hinge, or (2) addressing at the bottom electrode of the spacer. The advantage of using the first approach is the reduction of capacitance feedthrough caused by a nearby underlayer that carries signals. This approach has a smaller active optical area, because a larger post is needed to provide an electrical signal on one hinge while isolating the signal from the three others. Our chip uses the first approach. The next two sections briefly describe the chip architecture and process flow with a cross section of the flexure-beam micromirror device. The fourth section illustrates the modeling effort for this device. The fifth section then summarizes the characterization and performance of the device.

Hologram reconstruction by use of optical wavelet transform.

Abstract: High-speed in-line holography is used to visualize the trajectories of glass fibers being drawn out in a turbulent flame. To improve the signal-to-noise ratio, the images are not observed by a conventional reconstruction setup, but the holographic plate is placed directly on the input plane of a wavelet-transform optical system. This processing system is based on a VanderLugt correlator with inclusion of an electrically addressed spatial light modulator. The shape of the matched filters is deduced by successive rotation and dilatation operations of wavelet functions in the Fourier domain. We estimate the three-dimensional location of a fiber element and its orientation by searching for the daughter wavelet that yields the maximum intensity on the output plane of the correlator, which also contains the reconstructed image. The results are compared with those obtained by conventional optical reconstruction. The signal-to-noise ratios of the images observed on the output plane are improved. Moreover, it is shown that the axis coordinate accuracy is improved to Δz = ±50 µm, instead of ±0.5 mm for holographic reconstruction.

Match filters for a real time fingerprint sensor and verification system

Abstract: A real time fingerprint verification system includes a recording device and a verification device each having a fingerprint scanner for generating a flat, dimensionally undistorted, high contrast, fingerprint image, and an intensity sensitive, spatial light modulator (SLM) for receiving and transforming the flat fingerprint image into a planar, coherent light image. In the recording device, the planar coherent light image beam of the fingerprint from the SLM is Fourier transformed, and input into a microscope objective lens system which expands the Fourier transformed beam image sufficiently to allow mechanical blocking of its central portion or order, whereupon it is directed to interact as an object beam with a reference beam from the particular coherent light source to record a holographic matched filter. In the verification device, the planar coherent light image beam of the fingerprint is Fourier transformed and input into a microscope objective lens system to allow similar mechanical blocking of its central portion or order whereupon it is directed to interrogates a previously recorded holographic matched filter of a fingerprint image as an object beam for determining a match or not between the respective recorded and interrogating images. The spatial light modulator (SLM) in both the respective recording and verification devices enables phase correlation (optical path length determination) of one device to another device. X-Y alignment and rotational orinentation of the respective real time image and holographic matched filter image is accomplished by jittering (orbiting and angularly oscillating) either the interrogating object beam, real time, relative to the matched filter or visa versa.