 Optical phase filter using liquid crystal |
| OF THE PREFERRED EMBODIMENTS In FIG. 4, 4 is an optical phase filter using liquid crystals, 5 and 6... |
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| Twisted nematic liquid crystal display device |
| The present invention relates to a twisted nematic liquid crystal display device comprising a first ... |
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| Complex spatial modulator |
| What is claimed is: 1. An apparatus for effecting both amplitude and phase spatial modulation of a ... |
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| Active phase and amplitude modulator |
| These and other objects are obtained by replacing the variable resistor-reflective hybrid ... |
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| Projection display apparatus |
| The present invention is directed in view of the above respects towards a projection display ... |
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| Spatial light modulator with full complex light modulation capability |
| A method for full complex light modulation is described. Full complex light modulation allows the ... |
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| Differential amplifiers |
| It is an object of the present invention to provide a differential amplifier in which this ... |
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| Holograms in photorefractive materials |
| OF DRAWINGS Referring now more particularly to the drawing, like numerals indicate like pars and ... |
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| Liquid crystal light shutter |
| The present invention is therefore intended to eliminate the above-mentioned drawbacks and the ... |
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Self-powered optically addressed spatial light modulator
| Details |
Inventors: Moddel, Garret R.;
Assignee: The University of Colorado Foundation, Inc. (Boulder, CO)
Primary Examiner: Sikes; William L.
Assistant Examiner: Trice; Ron
Attorney, Agent or Firm: Hancock; Earl C., Sirr; Francis A.
A self-powered liquid crystal spatial light modulator is disclosed having a pair of spaced transparent glass plates, on each plate of which a transparent electrically conductive film is coated so as to be in confronting relation. A voltage/current generating, photovoltaic/photodiode, light sensitive layer is coated onto one of the conductive films. A liquid crystal layer is confined between the other conductive film and the light sensitive layer. A shorting circuit element connects the two conductive films. This shorting circuit element may be internal or external to the spatial light modulator. A pixel area of the spatial light modulator is addressed by a beam of light that illuminates the pixel area and operates to activate a corresponding area of the light sensitive layer. The voltage/current that is generated in this area of the light sensitive film causes a current to flow through the shorting circuit element, to thereby activate, switch or charge the corresponding area of the liquid crystal layer. Transmission mode and reflection mode spatial light modulators are described. |
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DETAILED DESCRIPTION This invention relates to a device that modulates a reading light wavefront that is transmitted through the device, or in an alternate embodiment is reflected by the device, in response to the device being written by a writing light source, i.
e.
this invention relates to spatial light modulators (SLMs).
In optically addressable modulators of this type the reading light may also comprise the writing light, wherein the light is partially absorbed in, and thus activates, the photosensitive layer.
The device of this invention differs from prior art devices of this general class in that no externally applied electrical power is required.
Rather, the entire multi-PEL area of the SLM is covered by an internally located photovoltaic/photodiode light sensitive layer, such that selective write activation of a pixel or PEL area within this light sensitive layer causes a localized voltage to be generated only in these selectively activated PEL areas, and thus causes only the corresponding PEL areas of an adjacent liquid crystal layer to be switched.
A wide range of applications exist for the device, including use as an image amplifier, an incoherent-to-coherent converter, an infrared-to-visible converter, etc.
.
Some applications suited to the self-powered device of the invention are self-darkening window panes, sunglasses and safety goggles.
More specifically, a SLM in accordance with the invention includes two transparent glass sheets that are each coated with a layer of transparent electrically conducting material, a voltage/current generating light sensitive layer and a liquid crystal layer are sandwiched between the two conducting layers, and an electrical conductor means providing a short circuit (i.
e.
a low impedance circuit) interconnects the two conducting layers.
The voltage/current generating light sensitive layer is preferably a hydrogenated amorphous silicon (a-Si:H) photodiode layer.
The liquid crystal layer is preferably a ferroelectric crystal (FLC) layer operating in its asymmetric and not-bistable mode
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