Grey-scale representation using binary spatial light modulators in coherent optical processor

Claim 1

In a coherent optical processor comprising means for producing a coherent input beam of light, spatial modulation means for receiving the input beam and for spatially modulating the input beam at a plurality of spatially separate image pixels to produce a modulated beam having the image pixels spatially encoded thereon, and a transform lens for receiving the modulated beam, the improvement wherein the spatial modulation means comprises: means for dividing the input beam into N sub-beams directed along N respective sub-beam paths; N binary spatial light modulators, each binary spatial light modulator comprising an array of sub-pixels and being positioned in one or the sub-beam paths so as to receive the sub-beam and convert it into a modulated sub-beam, each sub-pixel either blocking or passing a portion of the sub-beam, one sub-pixel of each of the N binary spatial light modulators corresponding to each image pixel; means for combining the modulated sub-beams to produce the modulated beam and for directing the modulated beam onto the transform lens, the sub-beams being combined such that for each image pixel, light that has passed through the N corresponding sub-pixels is spatially combined; the optical path length from input beam to modulated beam being the same along each sub-beam path; and weighting means for modifying the intensity of the light following the N sub-beam paths by selected weighting values, the weighting values forming a series in which each of N-1 weighting values differs from the preceding weighting value by a factor of 4.

Claim 11

A method of spatially modulating an input beam at a plurality of spatially separate image pixels to produce a modulated beam having the image pixels spatially encoded thereon, the method comprising: dividing the input beam into N sub-beams directed along N respective sub-beam paths; passing each sub-beam through a binary spatial light modulator, each binary spatial light modulator comprising an array of sub-pixels and being positioned in one of the sub-beam paths so as to receive the sub-beam and convert into a modulated sub-beam, each sub-pixel either blocking or passing a portion of the sub-beam, one sub-pixel of each of the N binary spatial light modulators corresponding to each image pixel; combining the modulated sub-beams to produce the modulated beam such that for each image pixel, light that has passed through the N corresponding sub-pixels is spatially combined; the optical path length from input beam to modulated beam being the same along each sub-beam path; and causing the light following the N sub-beam paths to have its intensity modified by selected weighting values, the weighting values forming a series in which each of N-1 weighting values differs from the preceding weighting value by a factor of 4.

Claim 12

A method of spatially modulating an input beam at a plurality of spatially separate image pixels to produce a modulated beam having the image pixels spatially encoded thereon, the method comprising: dividing the input beam into N sub-beams directed along N respective sub-beam paths; passing each sub-beam through a binary spatial light modulator, each binary spatial light modulator comprising an array of sub-pixels and being positioned in one of the sub-beam paths so as to receive the sub-beam and convert into a modulated sub-beam, each sub-pixel either blocking or passing a portion of the sub-beam, one sub-pixel of each of the N binary spatial light modulators corresponding to each image pixel; combining the modulated sub-beams to produce the modulated beam such that for each image pixel, light that has passed through the N corresponding sub-pixels is spatially combined; the optical path length from input beam to modulated beam being the same along each sub-beam path; and causing the light following the N sub-beam paths to have its intensity modified by selected weighting values, the weighting values forming a series in which each of N-1 weighting values differs from the preceding weighting value by a factor of 4.