Showing papers on "Spatial light modulator published in 2006"

Tissue imaging system

Abstract: A tissue imaging system (200) for examining the medical condition of tissue (290) has an illumination optical system (205), which comprises a light source (220), having one or more light emitters, beam shaping optics, and polarizing optics. An optical beamsplitter (260) directs illumination light to an imaging sub-system, containing a spatial light modulator array (300). An objective lens (325) images illumination light from the spatial light modulator array to the tissue. An optical detection system (210) images the spatial light modulator to an optical detector array. A controller (360) drives the spatial light modulator to provide time variable arrangements of on-state pixels. The objective lens operates in a nominally telecentric manner relative to both the spatial light modulator and the tissue. The polarizing optics are independently and iteratively rotated to define variable polarization states relative to the tissue. The modulator pixels optically function like pinholes relative to the illumination light and the image light.

Dynamic manipulation of Bose-Einstein condensates with a spatial light modulator

Abstract: We manipulate a Bose-Einstein condensate using the optical trap created by the diffraction of a laser beam on a fast ferroelectric liquid crystal spatial light modulator. The modulator acts as a phase grating which can generate arbitrary diffraction patterns and be rapidly reconfigured at rates up to 1 kHz to create smooth, time-varying optical potentials. The flexibility of the device is demonstrated with our experimental results for splitting a Bose-Einstein condensate and independently transporting the separate parts of the atomic cloud.

Holographic femtosecond laser processing with multiplexed phase Fresnel lenses

Abstract: Holographic femtosecond laser processing with multiplexed phase Fresnel lenses for high-speed parallel fabrication of microstructures is proposed. Use of a spatial light modulator (SLM) allows independent tunability of the diffraction peaks, three-dimensional parallelism, and arbitrary, variable features. The diffraction peaks are made uniform by changing the center phase and size of each phase Fresnel lens while taking account of the intensity distribution of the irradiated laser pulse and the spatial frequency response of the SLM.

Device for holographic reconstruction of three-dimensional scenes

Abstract: A device for holographic reconstruction of three-dimensional scenes includes optical focusing means which directs sufficiently coherent light from light means to the eyes of at least one observer via a spatial light modulator that is encoded with holographic information. The device has a plurality of illumination units for illuminating the surface of the spatial light modulator (SLM); each unit comprises a focusing element (21/22/23 or 24), and a light means (LS1/LS2/LS3 or LS4) that emits sufficiently coherent light such that each of these illumination units illuminates one separate illuminated region (R1/R2/R3 or R4) of the surface, whereby the focusing element and the light means are arranged such that the light emitted by the light means (LS1 - LS4) coincides close to or at the observer eyes.

Generation of achromatic Bessel beams using a compensated spatial light modulator

Abstract: We report the creation of white-light, achromatic Bessel beams using a spatial light modulator and a prism to compensate for the dispersion. Unlike the Bessel beam created by a refractive axicon, this achromatic beam has a radial wavevector and hence an intensity cross-section which is independent of wavelength. The technique also lends itself to the generation of higher order Bessel beams with an on-axis optical vortex and associated orbital angular momentum.

Remote metrology by comparative digital holography

Abstract: A method for the remote comparison of objects with regard to their shape or response to a load is presented. The method allows interferometric sensitivity for comparing objects with different microstructure. In contrast to the well-known incoherent techniques based on inverse fringe projection this new approach uses the coherent optical wave field of the master object as a mask for the illumination of the sample object. The coherent mask is created by digital holography to allow instant access to the complete optical information of the master object at any place desired. The mask is reconstructed by a spatial light modulator (SLM). The optical reconstruction of digital holograms with SLM technology allows modification of reconstructed wavefronts with respect to improvement of image quality, the skilled introduction of additional information about the object (augmented reality), and the alignment of the master and test object.

Optical apparatus with flipped compound prism structures

Abstract: An optical apparatus comprises a light source, an optical member and a spatial light modulator. The optical member comprises optically transmissive material and has a textured major surface receiving light from the light source. The textured surface comprises first and second pluralities of non-intersecting elongate features. The pluralities are angled with respect to each other by less than about 90° and intersect each other so as to form total internal reflection structures. The spatial light modulator has rows or columns of pixels for receiving light from the optical member at a major surface. The light source may be (i) a light guide, or (ii) a source of light providing, to the optical member, light having a peak luminance that is shifted from a normal direction to the textured major surface by more than about 30°.

Display device, lighting device and projector

Abstract: The object is to provide a display device that is capable of displaying an image with high luminance and a wide color reproduction range under simple control. The display device includes a light source device that emits first to fourth illumination lights, a spatial light modulator that modulates the illumination lights, and a controller. The controller allows the first and the second illumination lights to time-sequentially enter an identical illumination area of the spatial light modulator, and allows the third and the fourth illumination lights to individually enter the spatial light modulator so as to avoid them from being superimposed on the first and the second illumination lights.

Analysis of a collinear holographic storage system: introduction of pixel spread function

Abstract: Image formation in a collinear holographic storage system was analyzed. The wavefront from each pixel of a spatial light modulator was regarded as a plane wave in the recording medium, and its wave vector was determined by the position of the pixel. The hologram in the recording medium was treated as the summation of all gratings written by all combinations of two plane waves. The image of a data page was formed by diffraction of the reference waves by all gratings. The results of the simulation showed good agreement with experiment. We introduced the pixel spread function to describe the image formation characteristics. Analysis of the pixel spread function reveals that a radial-line pixel pattern for reference waves gave a sharper image than other reference pixel patterns. It is also shown that a random phase modulation applied to each reference pixel improved the image formation.

A polarization-independent liquid crystal spatial light modulator

Abstract: We report our recent experimental results on a new polarization-independent, liquid crystal (LC) spatial light modulator (SLM) Based on a periodic nematic director profile, the modulator acts as a switchable diffraction grating with only 0th- and ±1st-orders at efficiencies of ≥ 99%, manifests contrast ratios ~600:1 (for laser light), switching times of ~2ms, and threshold voltages of < 1V/μm Results of modulating broadband, unpolarized light from light-emitting-diodes (LEDs) indicates that contrast ratios are ~100:1 so far Note that incoherent scattering for visible light is very low, and that samples are typically completely defect-free over large areas An important feature of this diffractive polarization-independent SLM compared to its predecessors is its potential to achieve much larger diffraction angles, which enables a larger aperture (and etendue) In addition to describing the fabrication and characteristics of this SLM in general, we report on our initial progress in implementing a projection display system All of the surprising and useful results from this grating arise from its continuous nematic director, which is most properly classed as a switchable polarization grating (PG) The SLM described here offers the inherent advantages polarization-independence at the pixel-level and fairly fast switching with nematic LCs, while maintaining similar switching voltages, cell thickness, contrast ratios, and materials

Free space adaptive optical interconnect at 1.25 Gb/s, with beam steering using a ferroelectric liquid-crystal SLM

Abstract: A free space adaptive optical interconnect is reported, in which an optically modulated channel from a vertical-cavity surface-emitting laser at 1.25 Gb/s is steered using reconfigurable binary phase gratings displayed on a ferroelectric liquid crystal on silicon (LCOS) spatial light modulator (SLM), to correct for misalignment. The optical system, and addressing scheme to maintain a transparent optical path, is described. The measured optical losses total 13.6 dB, sufficient to give a bit error rate (BER) of 10/sup -12/ with current optical transmitter and receiver technology. This is, to our knowledge, the first demonstration of a high-speed data transmission through an adaptive optical interconnect using an "off-the-shelf" commercial ferroelectric display panel.

Projector and optical device

Abstract: To provide a projector or the like, which use a solid-state light-emitting element as light source and which provides a bright, stable, and uniform projection image, the present invention includes: a light source to emit light; a spatial light modulator to modulate the light from the light source in accordance with an image signal; and a projector lens to project the light modulated by the spatial light modulator. The spatial light modulator is a tilt mirror device including a movable mirror element that reflects the light from the light source in the direction of the projector lens or in the direction other than that of the projector lens. The invention may further include a light-intensity measuring section provided in an imaging position of the light source or in the vicinity of the imaging position to measure the light intensity of the light reflected in the direction other than that of the projector lens; and a light-source controller to control the light source in accordance with the signal from the light-intensity measuring section.

Light enhancing structures with a plurality of arrays of elongate features

Abstract: Various embodiments comprise light recycling films comprising an array of parallel ridges and grooves that form prisms that selectively reflect or transmit light. In some embodiments, the light recycling film may be used in displays that include spatial light modulators comprising a plurality of pixels. The light recycling film can limit the field-of-view of the display and enhance the luminance within that field-of-view. Various embodiments comprising multiple arrays of ridges and/or grooves can enhance uniformity of illumination of the pixels in the spatial light modulator and reduce Moire effects.

Atom guiding along high order Laguerre–Gaussian light beams formed by spatial light modulation

Abstract: A spatial light modulator (SLM) has been used to create high quality Laguerre–Gaussian (LG) light beams, which have been used to study the guiding of cold rubidium atoms. The SLM allows real-time variation of the hollow guiding beam and permits direct comparison of the guided atom fluxes for different LG modes with minimal adjustment of the other optical components. It is demonstrated that, by increasing the azimuthal index l of the Laguerre–Gaussian beam, the radiation pressure pushing the trapped atoms may be reduced while maintaining the same guided flux. This is the first comparative study of hollow beam atom guiding, and further demonstrates the versatility of the SLM for studies in atom optics.

Micro-mirror based display device having an improved light source

Abstract: A display device includes one or more light emitting diodes (LEDs) configured to emit light and a spatial light modulator comprising one or more tiltable micro mirrors each configured to receive the light emitted from the one or more LEDs and reflect the emitted light in two or more directions.

Efficient implementation of a spatial light modulator as a diffractive optical microlens array in a digital Shack-Hartmann wavefront sensor.

Abstract: A traditional Shack-Hartmann wavefront sensor (SHWS) uses a physical microlens array to sample the incoming wavefront into a number of segments and to measure the phase profile over the cross section of a given light beam. We customized a digital SHWS by encoding a spatial light modulator (SLM) with a diffractive optical lens (DOL) pattern to function as a diffractive optical microlens array. This SHWS can offer great flexibility for various applications. Through fast-Fourier-transform (FFT) analysis and experimental investigation, we studied three sampling methods to generate the digitized DOL pattern, and we compared the results. By analyzing the diffraction efficiency of the DOL and the microstructure of the SLM, we proposed three important strategies for the proper implementation of DOLs and DOL arrays with a SLM. Experiments demonstrated that these design rules were necessary and sufficient for generating an efficient DOL and DOL array with a SLM.

Homogenized Fourier transform holographic data storage using phase spatial light modulators and methods for recovery of data from the phase image.

Abstract: We present a method for homogenizing the Fourier spectrum for holographic digital data storage by use of a phase spatial light modulator (SLM), and methods for the recovery of data from a phase image are implemented and discussed. Binary digital data are displayed on a phase SLM operating in 0 and π phase modes to optimally remove the intense dc peak so as to obtain a homogenized Fourier spectrum. Methods based on holographic interferometry have been developed and employed for recovery of the original amplitude data page from the phase-data page. A new edge-detection-based method also has been demonstrated and analyzed for reconstruction of the original data. Experimental results are presented to confirm the feasibility of these novel techniques.

Holographic display devices

Abstract: This invention relates to electronic devices incorporating a holographic projector. A holographic projection module for a consumer electronic device, the holographic projection module comprising: at least one substantially monochromatic light source (12); a spatial light modulator (24) (SLM) to phase modulate light (22) from said light source to provide a phase hologram for generating a two-dimensional displayed image (14); projection optics to project said phase modulated light to form said two-dimensional displayed image; wherein said projection optics comprise an optical system (26) configured to demagnify a conventional, non-holographic image, to increase the divergence of said light forming said displayed image,- and a digital signal processor (100) to generate data for a plurality of temporal holographic sub frames from a desired image for display, for modulating said SLM, such that temporal averaging amongst the subframes reduces the perceived level of noise, in said displayed image when images corresponding to the subframes are displayed successively and sufficiently fast that they are integrated together in the eye of a human observer.

Generation of hollow beams by using a binary spatial light modulator.

Abstract: We demonstrate the generation of hollow laser beams by using a binary spatial light modulator and compare the results with those for a continuous modulator The binary phase modulator produces beams that have continuous, azimuthally varying phase profiles and can be dynamically changed with kilohertz refresh rates The intensity and phase profiles are recorded through the focus of an imaging lens and are compared with scalar diffraction theory We highlight properties of the beams relevant to optical dipole traps

Dynamic compensation of chromatic aberration in a programmable diffractive lens

Abstract: A proposal to dynamically compensate chromatic aberration of a programmable phase Fresnel lens displayed on a liquid crystal device and working under broadband illumination is presented. It is based on time multiplexing a set of lenses, designed with a common focal length for different wavelengths, and a tunable spectral filter that makes each sublens work almost monochromatically. Both the tunable filter and the sublens displayed by the spatial light modulator are synchronized. The whole set of sublenses are displayed within the integration time of the sensor. As a result the central order focalization has a unique location at the focal plane and it is common for all selected wavelengths. Transversal chromatic aberration of the polychromatic point spread function is reduced by properly adjusting the pupil size of each sublens. Longitudinal chromatic aberration is compensated by making depth of focus curves coincident for the selected wavelengths. Experimental results are in very good agreement with theory.

Polarization encoding and multiplexing of two-dimensional signals: application to image encryption

Abstract: We discuss an optical system that encodes an input signal to a polarization state, using a spatial light modulator (SLM). Using two SLMs the optical system multiplexes two 2D signals in the polarization domain, and we demonstrate the multiplexing of two binary images. The encryption and decryption of two binary images using an xor operation is also presented.

Quasi-automatic phase-control technique for chirp compensation of pulses with over-one-octave bandwidth-generation of few- to mono-cycle optical pulses

Abstract: This paper introduces our self-recognition type of the computer-controlled spectral phase compensator (SRCSC), which consists of a greatly accurate phase manipulator with a spatial light modulator (SLM), a highly sensitive phase characterizer using a modified spectral phase interferometry for direct electric field reconstruction (M-SPIDER), and a computer for phase analysis and SLM control operating in the immediate feedback (FB) mode. The application of the SRCSC to adaptive compensation of various kinds of complicated spectral phases such as nonlinear chirped pulses with a weak intensity, induced-phase modulated pulses, photonic-crystal-fiber (PCF) output pulses, and nonlinear chirped pulses exceeding a 500-rad phase variation over-one-octave bandwidth demonstrated that the SRCSC is significantly useful for compensation of arbitrary nonlinear chirp and hence enables us to generate quasi-monocycle transform-limited (TL) pulses with a 2.8-fs duration. To the best of our knowledge, this 1.5-cycle pulse is the shortest single pulse with a clean temporal profile in the visible to near-infrared region.

Light enhancing structures with three or more arrays of elongate features

Abstract: Various embodiments comprise light recycling films comprising an array of parallel ridges and grooves that form prisms that selectively reflect or transmit light. In some embodiments, the light recycling film may be used in displays that include spatial light modulators comprising a plurality of pixels. The light recycling film can limit the field-of-view of the display and enhance the luminance within that field-of-view. Various embodiments comprising multiple arrays of ridges and/or grooves can enhance uniformity of illumination of the pixels in the spatial light modulator and reduce Moire effects.

Spatial Light Modulator

Abstract: An interferometric spatial light modulator comprises of two cavities. One is the optical resonant cavity having a partially reflective film and a movable reflective membrane as two walls, and the other is the electromechanical actuation cavity having the movable reflective membrane and a bottom metal layer as electrodes. The spatial light modulator is built on silicon substrate and is actively addressed. A microdisplay apparatus of such spatial light modulators and a projection display system using such microdisplay are also disclosed.

System and method for varying exposure time for different parts of a field of view while acquiring an image

Abstract: A system and method for exposing different parts of a single field of view for various and differing lengths of time while capturing an image is provided. For astrophotography, unwanted light pollution or over-saturation bleeding from nearby or obtrusive stars may be greatly reduced or eliminated while still capturing the image of the nearby brighter star in the same field of view. Also, a system and method for real-time contrast control while capturing an image to optimize signal-to-noise ratio for various parts of the captured image, is provided. An embodiment of the present invention provides such techniques by using spatial light modulator devices, such as a digital micro-mirror device, to controllably mask different portions of light from an image that expose film or a charge-coupled device. A system and method for a way to use a spatial light modulator device as an active and controllable mask for photolithography, is provided.

Active, LCoS based laser interferometer for microelements studies.

Abstract: The modification of classical Twyman-Green interferometer by implementation of Liquid Crystal on Silicon (LCoS) spatial light modulator as the reference mirror allows introducing arbitrary phase in the reference wavefront. This special capability is applied to facilitate the measurements of shape and deformation of active microelements and extend the range of such measurement. This can be realized by introducing linear or circular spatial carrier frequency into interferogram or by compensating object wavefront deformation. Moreover LCoS display can be used as an accurate phase shifter if the proper calibration is introduced. The analysis of sources of measurement errors introduced by LCoS display is presented and the ways of their elimination are discussed. The possible application of LCoS based laser interferometer for initial microelement shape determination and transient deformation monitoring as well as active reference phase modification are shown and experimentally confirmed during silicon micromembranes studies.

Programmable fabrication of spatial structures in a gas jet by laser machining with a spatial light modulator

Abstract: Programmable fabrication of longitudinal spatial structures in a gas jet was achieved by using laser machining with a liquid-crystal spatial light modulator as the pattern mask. By this technique single-shot fabrication of arbitrary gas and/or plasma structures is demonstrated, which establishes the crucial step toward raising the designs and applications of high-field plasma devices to the level of adaptive feedback optimization.

Cold atom guidance using a binary spatial light modulator.

Abstract: We have guided cold (85)Rb atoms in a blue-detuned, high-order hollow laser beam generated by a binary spatial light modulator. The binary holograms written to the modulator produce smooth hollow laser beams with steep intensity walls that can be updated with a 1.6 kHz refresh rate. We analyze the guiding laser beams numerically and experimentally, and show that the atoms are exposed to an average intensity that is ~2% of the maximum intensity of the guide at a laser detuning of 1 GHz and 2 mW of optical power.

Programmable Photonic Microwave Filters With Arbitrary Ultra-Wideband Phase Response

Abstract: We present a coherent optical signal-processing approach for synthesis of programmable microwave phase filters over an ultra-wideband. Our scheme relies on a programmable optical phase filter implemented in a pulse-shaping geometry incorporating a spatial light modulator and hyperfine (~600-MHz spectral resolution) optical spectral disperser. The user-defined optical phase filter is directly transferred to the electrical domain through heterodyne conversion, and the overall system response is characterized via vector network analyzer measurements. We illustrate our approach by synthesizing linear, quadratic, and cubic spectral phase functions over a 20-GHz band. To our best knowledge, this is the first realization of programmable arbitrary microwave phase filters over such a bandwidth