Interferometric/feedback spatial light modulation system and method

Claim 2

A spatial light modulation system for spatially encoding a coherent readout beam with information from a noncoherent input light beam, comprising: a light modulator adapted to receive a noncoherent input light beam and a coherent readout light beam, and to spatially encode the input spatial light pattern onto the readout beam, means responsive to the readout beam for forming a feedback beam having a spatial encoding which varies in a negative fashion with respect to spatial variations in the input beam, and means for combining the feedback beam with the input beam in a negative feedback loop, thereby enhancing the responsivity of the readout beam to variations in the input beam.

Claim 3

The system of claim 1, wherein the light modulator encodes intensity variations in the input beam to phase variations in the readout beam, further comprising means for establishing a reference beam having a predetermined spatial phase relationship to an unencoded readout beam, and means for combining the reference and encoded readout beams to produce an output beam with a spatial intensity pattern corresponding to the input beam intensity pattern, and the feedback beam with a spatial intensity pattern that varies in a manner generally complementary to variations in the output beam pattern.

Claim 4

The system of claim 2, wherein the reference beam is established with a generally 90° spatial phase differential with respect to an unencoded readout beam from the modulator.

Claim 5

The system of claim 2, wherein the readout and reference beams are formed from a common beam source.

Claim 6

The system of claim 4, wherein the reference and readout beams are established by a laser, a beam splitter and a reflector means, the beam splitter being positioned to split a beam from the laser into readout and reference beams, the modulator being positioned to encode and direct the readout beam back to the beam splitter, the reflector means being positioned to reflect the reference beam back to the beam splitter with said predetermined spatial phase relationship to the readout beam, the beam splitter combining the reflected reference and encoded readout beams into said output and feedback beams.

Claim 7

The system of claim 1, wherein the light modulator and the means for forming a feedback beam are selected to produce a feedback beam having spatial intensity variations I F (x,y) which vary with the input beam spatial intensity variations I IN (x,y) substantially in accordance with: I.sub.F (x,y)=-I.sub.IN (x,y)G/(1+G), where G is the loop gain of the feedback system.

Claim 8

A spatial light modulation system for obtaining an output coherent spatial light pattern which corresponds to an input noncoherent spatial light intensity pattern, comprising: a light modulator adapted to receive a noncoherent input optical beam and a coherent readout optical beam, and to spatially encode the intensity pattern of the input beam onto the phase of the readout beam, means for establishing a coherent reference beam and the coherent readout beam such that the reference beam has as predetermined spatial phase relationship to the unencoded readout beam, means for combining the reference and readout beams to produce an output beam with a spatial intensity pattern corresponding to the input beam intensity pattern, and means for providing a coherent feedback beam in combination with the noncoherent input optical beam to the light modulator to provide a combined coherent-noncoherent input to the light modulator.

Claim 9

A spatial light modulation system for obtaining an output coherent spatial light pattern which corresponds to an input noncoherent spatial light intensity pattern, comprising: a light modulator adapted to receive a noncoherent input optical beam and a coherent readout optical beam, and to spatially encode the intensity pattern of the input beam onto the phase of the readout beam, means for establishing a coherent reference beam and the coherent readout beam such that the reference beam has as predetermined spatial phase relationship to the unencoded readout beam, means for combining the reference and readout beams to produce an output beam with a spatial intensity pattern corresponding to the input beam intensity pattern, and means for providing a coherent feedback beam in combination with the noncoherent input optical beam to the light modulator to provide a combined coherent-noncoherent input to the light modulator.

Claim 10

The system of claim 7, wherein the reference beam is established with a generally 90° spatial phase differential with respect to the unencoded readout beam.

Claim 11

The system of claim 7, wherein the readout and reference beams are formed from a common coherent beam source.

Claim 12

The system of claim 9, wherein the means for establishing the reference and readout beams, includes the common coherent beam source, a beam splitter and a reflector means, the beam splitter being positioned to split a beam from the common coherent beam source into readout and reference beams, the modulator being positioned to encode and direct the readout beam back to the beam splitter, the reflector means being positioned to reflect the reference beam back to the beam splitter with said predetermined spatial phase relationship to the readout beam, the beam splitter combining the reflected reference and encoded readout beams into said output beam.

Claim 13

An intensity-to-intensity spatial light modulation system, comprising: an amplitude-to-phase spatial light modulator, means for directing a noncoherent, spatially intensity modulated input beam as an input to the modulator, means for forming a coherent readout beam, means for directing the readout beam onto the modulator, the readout beam being reflected from the modulator with a spatial phase modulation corresponding to the input beam's spatial intensity modulation, means for forming a reference beam having a predetermined spatial phase relationship with respect to an unencoded readout beam, means for combining the reference and encoded readout beams to produce an output beam with a spatial intensity pattern determined by the phase-interference pattern between the reference and readout beams, and a feedback beam with a spatial intensity pattern that varies in a manner generally complementary to variations in the output beam pattern, and means for combining the feedback beam with the input beam in a negative feedback loop, thereby enhancing the responsivity of the output beam to variations in the input beam.

Claim 14

An intensity-to-intensity spatial light modulation system, comprising: an amplitude-to-phase spatial light modulator, means for directing a noncoherent, spatially intensity modulated input beam as an input to the modulator, means for forming a coherent readout beam, means for directing the readout beam onto the modulator, the readout beam being reflected from the modulator with a spatial phase modulation corresponding to the input beam's spatial intensity modulation, means for forming a reference beam having a predetermined spatial phase relationship with respect to an unencoded readout beam, means for combining the reference and encoded readout beams to produce an output beam with a spatial intensity pattern determined by the phase-interference pattern between the reference and readout beams, and a feedback beam with a spatial intensity pattern that varies in a manner generally complementary to variations in the output beam pattern, and means for combining the feedback beam with the input beam in a negative feedback loop, thereby enhancing the responsivity of the output beam to variations in the input beam.

Claim 15

The system of claim 11, wherein the reference and readout beams are established by a laser, a beam splitter and a reflector means, the beam splitter being positioned to split a beam from the laser into readout and reference beams, the modulator being positioned to encode and direct the readout beam back to the beam splitter, the reflector means being positioned to reflect the reference beam back to the beam splitter with said predetermined spatial phase relationship to the readout beam, the beam splitter combining the reflected reference and encoded readout beams into said output and feedback beams.

Claim 16

The system of claim 12, wherein the round trip distance for the reference beam between the beam splitter and reflector means differs from the round trip distance for the readout beam between the beam splitter and modulator by approximately 1/4 the laser beam wavelength, thereby establishing a generally 90° spatial phase differential between the reference beam and an unencoded readout beam the polarity of the phase differential being selected so that the spatial intensity of the output beam varies in positive proportion to that of the input beam.

Claim 17

The system of claim 11, wherein the light modulator and the means for forming a feedback beam are selected to produce a feedback beam having spatial intensity variations I F (x,y) which vary with the input beam spatial intensity variations I IN (x,y) substantially in accordance with: I.sub.F (x,y)=-I.sub.IN (x,y)G/(1+G), where G is the loop gain of the feedback system.

Claim 20

The method of claim 15, wherein spatial intensity variations in the input beam are encoded to phase variations in the readout beam, and further comprising the steps of establishing a reference beam having a predetermined spatial phase relationship to an unencoded readout beam, and combining the reference and encoded readout beams to produce an output beam with a spatial intensity pattern corresponding to the input beam intensity pattern and the feedback beam with a spatial intensity pattern that varies in a manner generally complementary to variations in the output beam pattern.

Claim 21

The method of claim 16, wherein the reference beam is established with a generally 90° spatial phase differential with respect to an unencoded readout beam.

Claim 22

The method of claim 15, wherein the feedback beam is formed with spatial intensity variations I F (x,y) which vary with the input beam spatial intensity variations I IN (x,y) substantially in accordance with: I.sub.F (x,y)=-I.sub.IN (x,y) G/(1+G), where G is the feedback loop gain.

Claim 25

The method of claim 19, wherein the reference beam is established with a generally 90° spatial phase differential with respect to an unencoded readout beam, and the output beam is transmitted through a field stop to modify the contrast ratio.