Beam steering device
First Claim
1. An optical device comprising an array of elements, a beam of light being incident upon said array of elements, each element having a reflective back electrode and a single transparent front electrode common to the array, the back and front electrodes being disposed respectively behind and in front of a liquid crystal layer, the back electrodes being spaced apart to define said array, a waveplate disposed to provide polarisation independence and a reflective layer disposed behind the back electrodes to reflect light incident in the spaces between the back electrodes substantially in phase with the light reflected from the back electrodes, said array of elements to steer said beam of light.
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Accused Products
Abstract
A beam steering device uses a liquid crystal with an array of back electrodes. Voltages are applied to the array to cause a desired phase distribution across the array, the distribution being selected to steer a beam incident upon the array into a desired direction. Reflective elements are disposed to reflect light incident in the spaces between the electrodes to reduce losses and to smooth the transitions in phase between adjacent electrodes.
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Citations
23 Claims
- 1. An optical device comprising an array of elements, a beam of light being incident upon said array of elements, each element having a reflective back electrode and a single transparent front electrode common to the array, the back and front electrodes being disposed respectively behind and in front of a liquid crystal layer, the back electrodes being spaced apart to define said array, a waveplate disposed to provide polarisation independence and a reflective layer disposed behind the back electrodes to reflect light incident in the spaces between the back electrodes substantially in phase with the light reflected from the back electrodes, said array of elements to steer said beam of light.
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16. A method of operating on a beam of light, the method comprising:
causing said beam of light to be incident upon a reflective liquid crystal device;
selecting a desired spatial phase modulation characteristic for said liquid crystal device thereby to provide a deflection of said beam of light to steer said beam of light from a first direction to a desired second direction; and
providing a spatial distribution of phase levels across said liquid crystal device to at least approximate to said desired characteristic;
wherein the step of providing a spatial distribution of phase levels comprises driving said liquid crystal at sequential spaced driving locations by providing electrodes at said discrete driving locations, and applying voltages to sequential electrodes to produce rising discrete phase levels due to the liquid crystal; and
smoothing transitions in phase between said spaced driving locations by providing further locations between said spaced driving locations, and reflecting said light through said liquid crystal in said further locations by providing spaces between the electrodes at said further locations and providing reflective elements in the spaces and behind the electrodes;
wherein said electrodes are reflective and disposed at a distance behind said electrodes such that light reflected thereby leaves said liquid crystal device substantially in phase with light reflected by said electrodes whereby said liquid crystal device is reflective.- View Dependent Claims (17, 21)
- 18. An optical device comprising an array of elements, a beam of light being incident upon said array of elements, each element having a reflective back electrode and a single transparent front electrode common to the array, the back and front electrodes being disposed respectively behind and in front of a liquid crystal layer, the back electrodes being spaced apart to define said array, and a reflective layer disposed behind the back electrodes to reflect light incident in the spaces between the back electrodes substantially in phase with the light reflected from the back electrodes, the device having a further planarising layer disposed over said back electrodes, said array of elements to steer said beam of light.
- 19. An optical device comprising an array of elements, a beam of light being incident upon said array of elements, each element having a reflective back electrode and a single transparent front electrode common to the array, the back and front electrodes being disposed respectively behind and in front of a liquid crystal layer, the back electrodes being spaced apart to define said array, and a reflective layer disposed behind the back electrodes to reflect light incident in the spaces between the back electrodes substantially in phase with the light reflected from the back electrodes, the device having a further planarising layer disposed level with said back electrodes, said array of elements to steer said beam of light.
Specification