Showing papers on "Spatial light modulator published in 2004"

Holographic generation of microtrap arrays for single atoms by use of a programmable phase modulator

Abstract: We have generated multiple micrometer-sized optical dipole traps for neutral atoms using holographic techniques with a programmable liquid-crystal spatial light modulator. The setup allows storing of a single atom per trap and addressing and manipulation of individual trapping sites.

Assembly of 3-dimensional structures using programmable holographic optical tweezers.

Abstract: The micromanipulation of objects into 3-dimensional geometries within holographic optical tweezers is carried out using modified Gerchberg-Saxton (GS) and direct binary search (DBS) algorithms to produce the hologram designs The algorithms calculate sequences of phase holograms, which are implemented using a spatial light modulator, to reconfigure the geometries of optical traps in many planes simultaneously The GS algorithm is able to calculate holograms quickly from the initial, intermediate and final trap positions In contrast, the DBS algorithm is slower and therefore used to pre-calculate the holograms, which are then displayed in sequence Assembly of objects in a variety of 3-D configurations is semi-automated, once the traps in their initial positions are loaded

Phase-only liquid crystal spatial light modulator for wavefront correction with high precision

Abstract: We introduce a novel parallel-aligned liquid-crystal (LC) spatial light modulator (SLM) that has been designed to operate in a phase-only mode for wave-front correction. We measured and analyzed theoretically the electro-optic characteristics of the LC SLM and obtained a peak-to-valley value of 0.07049lambda(lambda= 0.6328microm) after correction. A Strehl ratio of 0.989 indicates the approximate upper limit of an aberrated wave front that the LC SLM can correct when it is used in an adaptive optical system.

Phase calibration of spatially nonuniform spatial light modulators

Abstract: A new 512 x 512 pixel phase-only spatial light modulator (SLM) has been found to deviate from being flat by several wavelengths. Also, the retardation of the SLM relative to voltage varies across the device by as much as 0.25 wavelength. The birefringence of each pixel as a function of address voltage is measured from the intensity of the SLM between crossed polarizers. To these responses are added a reference spatial phase measured by phase shifting interferometry for a single address voltage. Fits to the measured data facilitate the compensation of the SLM to a root-mean-square wave-front error of 0.06 wavelength. The application of these corrections to flatten the full aperture of the SLM sharpens the focal plane spot and reduces the distortion of computer-designed diffraction patterns.

Micromirrors and off-diagonal hinge structures for micromirror arrays in projection displays

Abstract: A spatial light modulator (200) is disclosed, along with methods for making such a modulator, that comprises an array of micromirrors (201) each having a hinge (240) and a micromirror plate (210) held via the hinge on a substrate (202), the micromirror plate being disposed in a plane separate from the hinge and having a diagonal (211) extending across the micromirror plate, the micromirror plate being attached to the hinge such that the micromirror plate can rotate along a rotation axis (214) that is parallel to, but off-set from the diagonal of the micromirror plate. Also disclosed is a projection system that comprises such a spatial light modulator, as well as a light source, condensing optics, wherein light from the light source is focused onto the array of micromirrors, projection optics for projecting light selectively reflected from the array of micromirrors onto a target, and a controller for selectively actuating the micromirrors in the array.

Mixed vortex states of light as information carriers

Abstract: An original method for encoding of information into the spatial structure of mixed vortex states of light is proposed. It is based on the creation of pseudo-nondiffracting vortex patterns representing a controllable superposition of optical vortices with different topological charges. Weight coefficients of the superposition serve as carriers of information. The different topological charges of the vortices are used as 'markers' enabling vortex spatial separation and information decoding. The proposed concept of information encoding is verified experimentally by means of a spatial light modulator.

Independent phase and amplitude control of a laser beam by use of a single-phase-only spatial light modulator.

Abstract: A phase-only spatial light modulator is used in conjunction with a spatial filter to provide independent control of the phase and amplitude of a laser beam. Continuous amplitude modulation of the beam is achieved with a resolution relevant to beam shaping of high-energy laser beams. Amplitude beam correction in a closed loop is demonstrated.

Micromirrors with mechanisms for enhancing coupling of the micromirrors with electrostatic fields

Abstract: A micromirror device is disclosed, along with a method of making such a micromirror device that comprises a mirror plate, a hinge and an extension plate. The extension plate is formed on the mirror plate and between the mirror plate and the electrode associated with the mirror plate for rotating the mirror plate. The extension plate can be metallic or dielectric. Also disclosed is a method of making such a micromirror device. In particular, the extension plate is formed after the formation of the mirror plate. Moreover, also disclosed is a projection system that comprises a spatial light modulator having an array of such micromirrors, as well as a light source, condensing optics, wherein light from the light source is focused onto the array of micromirrors, projection optics for projecting light selectively reflected from the array of micromirrors onto a target, and a controller for selectively actuating the micromirrors in the array.

Overview and applications of Grating-Light-Valve-based optical write engines for high-speed digital imaging

Abstract: The Grating Light Valve (GLV) is a diffractive MOEMS spatial light modulator capable of very high-speed modulation of light combined with fine gray-scale attenuation. GLV-based products are field-proven in a variety of applications. In this paper, we describe the GLV device, its structure, theory of operation, and optical performance. The versatility and speed of the GLV device are described. We explain how the GLV device is integrated into an optical write engine to create a complete digital imaging system. In addition to the MOEMS die and drive electronics, the light engine also comprises illumination optics, Fourier filter, and imaging optics. We present current applications of the GLV device for high-resolution displays, and computer-to-plate printing, as well as future plans for digital imaging applications opened up by the unique properties of this diffractive MOEMS technology.

Projection system and method

Abstract: An image projection system and method are presented to project an image on at least one of first and second projection planes. The system comprises a light source system (102) including one or more light source assemblies operable to generate light of one or more predetermined wavelength range; a spatial light modulator (SLM) system (104) including one or more SLM units operable to spatially modulate input light in accordance with an image to be directly projected or viewed; and two optical assemblies (106) associated with two spatially separated light propagation channels, respectively, to direct light to, respectively, the first and second projection planes with desired image magnification (108A, 108B). The system is configured to selectively direct the input light propagating towards the SLM system or light modulated by the SLM system to propagate along at least one of the two channels associated with the first and second projection planes, respectively.

Integrated modulator illumination

Abstract: A spatial light modulator includes an array of elements to modulate light in accordance with image data. The modulator has a display panel having first and second surfaces arranged adjacent to the array of elements such that the second surface is directly adjacent the array of elements to allow a viewer to view an image produced by modulation of light The modulator may also include a light source to provide light to the display panel and illumination dots on the first surface of the display panel to reflect light from the source to the array of elements.

Transmissive spatial light modulator and method of manufacturing the same

Abstract: A transmissive spatial light modulator having a light-transmission area, comprises: a transparent substrate; a pixel drive circuit provided on the transparent substrate to form an area other than the light-transmission area; and a transmissive light modulation section including a micro-electromechanical element, the transmissive light modulation section being controlled by the pixel drive circuit and being provided above the pixel drive circuit.

Beamsplitting structures and methods in optical systems

Abstract: Various embodiments involving structures and methods for illumination can be employed, for example, in projectors, head-mounted displays, helmet-mounted displays, back projection TVs, flat panel displays as well as other optical systems. Certain embodiments may include prism elements for illuminating, for example, a spatial light modulator. Light may be coupled to the prism in some cases using fiber optics or lightpipes. The optical system may also include a diffuser having scatter features arranged to scatter light appropriately to produce a desired luminance profile. Other embodiments are possible as well.

Size selective trapping with optical "cogwheel" tweezers.

Abstract: We experimentally investigate the size-selective trapping behavior of Laguerre-Gaussian beams ("doughnut-beams") and "cogwheel"-shaped beams which are collinear superpositions of two doughnut beams of equal opposite helical index. Experimentally they are created by diffraction of a Gaussian laser beam at a high resolution refractive spatial light modulator (SLM). In the focus of an optical microscope such a beam looks similar to a "cogwheel", i.e. the light intensity is periodically modulated around the circumference of a sphere with a precisely adjustable diameter. In an optical tweezers setup these modes can be used to trap particles or cells, provided their sizes exceed the ring diameter by a fixed amount. This promises a convenient method of constructing an optical tweezers system in microscopy which acts as a passive sorter for particles of differing sizes.

3D electronic holography display system using a 100-megapixel spatial light modulator

Abstract: The display of 3D images containing all the depth cues required by the human vision system can be achieved using a reconfigurable Computer Generated Hologram (CGH) with high pixel count Giga-pixel scale displays or spatial light modulators are required in order to form directly viewable 3-D images of 05m in size A new Spatial Light Modulator (SLM) solution, Active Tiling (AT)1, has been developed by the authors to replay giga-pixel scale CGHs at video refresh rates This has overcome a key bottleneck preventing commercial development of electro-holography to date At the heart of an AT system is a set of replication optics which produces multiple images of an electrically addressed Spatial Light Modulator (SLM) on an optically addressed spatial light modulator (OASLM) Solutions employed within electronic holography will be discussed A holographic 3D display system using a 4 channel Active Tiling modulator with a new replay optics system has demonstrated directly viewable 3-D images and animations from 100 Mega-pixel CGH data This provided viewing of both horizontal parallax only (HPO) and full parallax 3-D images up to 140mm in size

Coherence and polarization of electromagnetic beams modulated by random phase screens and their changes on propagation in free space

Abstract: The spectral degree of coherence and of polarization of some model electromagnetic beams modulated by a polarization-dependent phase-modulating device, such as a liquid-crystal spatial light modulator, acting as a random phase screen are examined on the basis of the recent theory formulated in terms of the 2 x 2 cross-spectral density matrix of the beam. The phase-modulating device is assumed to have strong polarization dependence that modulates only one of the orthogonal components of the electric vector, and the phase of the phase-modulating device is assumed to be a random function of position imitating a random phase screen and is assumed to obey Gaussian statistics with zero mean. The propagation of the modulated beam is also examined to show how the spectral degrees of coherence and of polarization of the beam change on propagation, even in free space. The results are illustrated by numerical examples.

Display including a solid state light device and method using same

Abstract: A display (800) includes a solid state light device (810) and a spatial light modulator (830) in optical communication with the solid state light device. The solid state light device includes an array of solid state radiation sources (812) to generate radiation, where each solid state radiation source includes a controllable radiation output. The solid state light device further includes an array of optical concentrators (814), where each optical concentrator receives radiation from a corresponding one of the array of solid state radiation sources. The solid state light device further includes a plurality of optical fibers (816), where each of the plurality of optical fibers includes an input end (818) that receives concentrated radiation from a corresponding optical concentrator. The spatial light modulator includes a plurality of controllable elements operable to modulate light from the solid state light device.

Defining the trapping limits of holographical optical tweezers

Abstract: We report on the limitations of using a spatial light modulator (SLM) within optical tweezers to produce both lateral and axial displacements. We find that lateral displacements of optical traps are limited by the optical efficiency of the SLM, whereas the axial displacements are limited by the abberations of the objective lens. In addition, we show the SLM can be used for correcting abberations arising from trapping deep within the sample. The maximum possible lateral and axial displacements were 50 μm and 40 μm, respectively.

High fill ratio reflective spatial light modulator with hidden hinge

Abstract: A micro mirror array having a hidden hinge that is useful, for example, in a reflective spatial light modulator. In one embodiment, the micro mirror array includes spacer support walls, a hinge, a mirror plate and a reflective surface on the upper surface of the mirror plate, the reflective surface concealing the hinge and the mirror plate. The micro mirror array fabricated from a single material.

Method to detect a defective element

Abstract: The present invention relates to a method to detect at least one defective pixel in a spatial light modulator comprising numerous pixel elements. The spatial light modulator is imaged to a detector. A relayed image of a first chess-board pattern of pixels in said spatial light modulator is detected by said detector. A relayed image of a second chess-board pattern of pixels in said spatial light modulator is detected, which is inverted to the first chessboard pattern, by said detector. The relayed images of said first and second chessboard patterns are analyzed to detect differences between said detected images and theoretical images thereof.

Laser illuminated projection displays

Abstract: A projection video display includes a light source including an OPS-laser delivering laser radiation in multiple transverse modes (a multiple-transverse-mode OPS-laser). The display includes a spatial light modulator for spatially modulating the radiation from the multiple-transverse-mode OPS-laser in accordance with a portion of an image to be displayed. Projection optics project the spatially modulated light on a screen on which the image is to be displayed. In one example the OPS-laser is a diode-laser array pumped OPS-laser and is one of three lasers, one delivering red light, one delivering blue light, and the other delivering green light. The lasers are time modulated such that the spatial light modulator receives light from each of the lasers separately. The OPS laser is directly time modulated by periodically turning the diode-laser array on and off.

Dynamic array of dark optical traps

Abstract: A dynamic array of dark optical traps is generated for simultaneous trapping and arbitrary manipulation of multiple low-index microstructures. The dynamic intensity patterns forming the dark optical trap arrays are generated using a nearly loss-less phase-to-intensity conversion of a phase-encoded coherent light source. Two-dimensional input phase distributions corresponding to the trapping patterns are encoded using a computer-programmable spatial light modulator, enabling each trap to be shaped and moved arbitrarily within the plane of observation. We demonstrate the generation of multiple dark optical traps for simultaneous manipulation of hollow “air-filled” glass microspheres suspended in an aqueous medium.

Diffractive optical tweezers in the Fresnel regime.

Abstract: We demonstrate a flexible setup for holographic steering of laser tweezers in microscopy using a high resolution spatial light modulator (SLM). In contrast to other methods, hologram read-out is done in the off-axis Fresnel regime rather than in the typically used on-axis Fourier regime. The diffractive structure is calculated as a Fresnel hologram, such that after reflection at the SLM only the desired first diffraction order is guided to the input of an optical microscope, where it generates a tailored optical tweezers field. We demonstrate some advantageous features of this setup, i.e. undesired diffraction orders are suppressed, the optical traps can be easily steered in real-time by just "mouse-dragging" a hologram window at the SLM display, and a number of independently steerable optical traps can be generated simultaneously in a three-dimensional arrangement by displaying a corresponding number of adjacent hologram windows at the SLM screen.

Light distribution apparatus and methods for illuminating optical systems

Abstract: Various embodiments involving structures and methods for illumination can be employed, for example, in projectors, head-mounted displays, helmet-mounted displays, back projection TVs, flat panel displays as well as other optical systems Certain embodiments may include prism elements for illuminating, for example, a spatial light modulator Light may be coupled to the prism in some cases using fiber optics or lightpipes The optical system may also include a diffuser having scatter features arranged to scatter light appropriately to produce a desired luminance profile Other embodiments are possible as well

Versatile maskless lithography system with multiple resolutions

Abstract: A versatile maskless patterning system with capability for selecting rapidly among a plurality of projection lenses mounted on a turret. This provides the ability to rapidly select multiple choices for resolution and enables optimization of the combination of the imaging resolution and exposure throughput, making possible cost-effective fabrication of microelectronics packaging products. A preferred embodiment uses a digital micromirror device array spatial light modulator as a virtual mask. Another preferred embodiment use multiple closely spaced digital micromirror device array spatial light modulators to enhance throughput.

Optical combiner designs and head mounted displays

Abstract: Various embodiments involving structures and methods for illumination can be employed, for example, in projectors, head-mounted displays, helmet-mounted displays, heads-up displays, back projection TVs, flat panel displays as well as other optical systems. Certain embodiments may include prism elements for illuminating, for example, a spatial light modulator. Light may be coupled to the prism in some cases using fiber optics or lightpipes. The optical system may also include a diffuser having scatter features arranged to scatter light appropriately to produce a desired luminance profile. Ellipsoid- and parapoloid-shaped combiners may be employed in embodiments of displays such as for example head mounted displays, helmet mounted displays, and heads-up display. Other embodiments are possible as well.

Performance evaluation of a liquid-crystal-on-silicon spatial light modulator

Abstract: D optical phased array antennas formed by a liquid crystal on silicon (LCOS) spatial light modulator are described for free-space laser communication and high-resolution wavefront control. The device consists of an 2-D array of 10243768 phase modulator elements, each with controlled voltage, and can induce a phase shift from 0 to 2p for wavelengths up to the near IR. When the device is used as a wavefront corrector, 18.7 waves peak-valley (at 632.8 nm) of aberration in the op- tical system is corrected to a residual of 1/9 wave peak-valley, or 1/30 wave rms. The Strehl ratio improved from 0.006 to 0.83 after correction. An additional linear phase ramp was added to the correction phase ramp to simultaneously correct and steer the laser beam. Continuous steering over 64 mrad in the X-Y plane with a steering accuracy higher than 10 mrad has been obtained. The 1-D beam-steering efficiency is 80% at the maximum steering angle of 4 mrad. These results suggest that an LCOS device can be used to achieve very high-resolution wavefront control at very high efficiency. © 2004 Society of Photo-Optical Instrumentation Engineers.

High contrast spatial light modulator and method

Abstract: The upper portion of the high contrast SLM is fully covered by arrays of micro-mirrors with a flat optically reflective layer (102) on the upper surfaces and a pair of embedded torsion hinges (106) under the cavities in the lower portion of mirror plate (103). Torsion hinges (106) in the mirror plate (103) are fabricated to be part of the mirror plate (103) and are kept a minimum distance under the reflective surface to allow only a gap for a predetermined angular rotation. By minimizing the distances between a hinge rotating axes (106) to the upper reflective surfaces (102), the SLM effectively eliminates the horizontal displacement of each minor during an angular transition. According to the present invention, the gaps between adjacent mirrors in the array of SLM can be reduced to less than 0.2 microns to achieve the highest active reflection area fill-ratio of a micro-mirror array at the present time.

Color recapture for display systems

Abstract: A sequential color display system using a white light source to create a full color image projected onto an image plane. A dynamic filter, typically a series of moving dichroic filters, generates a series of primary colored light beams that are swept across the surface of a spatial light modulator. Typically all three primary colors are produced simultaneously by the dynamic filter. The illuminated portion of the dynamic filter is imaged onto the modulator and controller provides appropriate image data for each portion of the modulator in synchronization with the sweep of the primary color bands across the modulator surface. The primary color bands are modulated by the spatial light modulator and the modulated light is focused by lens onto the image plane. The viewer integrates the light arriving at each portion of the image plane over a frame period to provide the perception of a full-color image.