Patent ID: 7466468

Claim:
A two dimensional spatial radiation modulator adapted to be rotated about a rotation axis to modulate at least one component of an incident radiation beam to encode said beam, said modulator comprising: a substrate and at least one annular region substantially encompassing a plurality of non-contiguous sub-regions having optical characteristics substantially different from said substrate, said annular region comprising at least two annular segments, each said segment comprising a fractional rotation period of said modulator, said sub-regions in a first annular segment being patterned to form at least one pair of radiation filters located at different radii from said rotation axis and having substantially complementary modulation functions, said pair producing in response to the beam a first encoded component with a characteristic determined by the relative intensities of radiation from the beam incident on the at least one pair of filters; said sub-regions in a second annular segment being patterned to form at least one radiation filter that produces in response to the beam a second encoded component with a characteristic determined by the total intensity of radiation from the beam incident on said at least one radiation filter.