DESPECKLING LASER-IMAGE-PROJECTION SYSTEM
An optical device for projecting an image is disclosed. In one embodiment, the optical device includes a configurable optical diffuser adapted to produce a diffuse optical beam having a temporally varying pattern of angular divergence. The optical device further includes a plurality of lenslet pairs to shape the diffuse optical beam and a spatial light modulator to spatially modulate the shaped optical beam to project an image.
1 . An optical device for projecting an image, the optical device comprising:
a configurable optical diffuser adapted to produce a diffuse optical beam having a temporally varying pattern of angular divergence;
a fly's eye (FE) integrator adapted to shape the diffuse optical beam; and
a spatial light modulator (SLM) adapted to spatially modulate a shaped optical beam produced by the FE integrator to project the image.
2 . The invention of claim 1 , wherein:
the FE integrator comprises a plurality of lenslet pairs arranged side by side with each other; and
the plurality of lenslet pairs include different lenslet pairs that produce, on the SLM, a superposition of corresponding illuminated regions that is substantially independent of temporal variations introduced by the configurable optical diffuser.
3 . The invention of claim 2 , wherein the focal lengths of the lenslets in a lenslet pair are substantially matched.
4 . The invention of claim 1 , wherein the FE integrator comprises one or more lenslet pairs in which opposing faces are parts of a single optical piece.
5 . The invention of claim 1 , further comprising a pair of crossed cylindrical lenses to produce an optical beam applied to the configurable optical diffuser.
6 . The invention of claim 5 , wherein the crossed cylindrical lenses of said pair have different focal lengths.
7 . The invention of claim 1 , wherein the configurable optical diffuser comprises a transmissive liquid-crystal structure adapted to display a dynamically changing light-scattering pattern.
8 . The invention of claim 1 , wherein the configurable optical diffuser is a transmissive plate adapted for movement with respect to the FE integrator.
9 . The invention of claim 1 , further comprising a polarization beam splitter (PBS) to couple light from the FE integrator to the spatial light modulator.
10 . The invention of claim 1 , further comprising an illumination source including one or more lasers adapted to generate light applied to the configurable optical diffuser.
11 . The invention of claim 10 , wherein the one or more lasers include a first laser adapted to generate light having different angular divergence along at least two different axes orthogonal to the emission axis of the first laser.
12 . The invention of claim 1 , wherein the configurable optical diffuser is to receive light from a time-division multiplexed source.
13 . The invention of claim 1 , further comprising a color combiner adapted to direct multicolored light toward the configurable optical diffuser.
14 . An optical device for projecting an image, the optical device comprising:
a pair of crossed cylindrical lenses to provide collimated coherent light;
a moveable diffuser to receive the collimated coherent light to produce a diffuse optical beam having a temporally varying pattern of angular divergence; and
a plurality of lenslet pairs arranged side by side with each other and adapted to shape the diffuse optical beam.
15 . The invention of claim 14 , further comprising a spatial light modulator adapted to receive at least a portion of a shaped optical beam produced the by plurality of lenslet pairs.
16 . The invention of claim 15 , further comprising a polarization beam splitter adapted to direct at least a portion of the shaped optical beam toward the spatial light modulator.
17 . The invention of claim 14 , further comprising a light source including at least one coherent light emitter to be optically coupled to the pair of crossed cylindrical lenses.
18 . The inventions of claim 14 , wherein the plurality of lenslet pairs is configured as a fly's eye integrator structure.
19 . The invention of claim 14 , further comprising a light combiner adapted to direct light to the pair of crossed cylindrical lenses.
20 . The invention of claim 14 , wherein the plurality of lenslet pairs include at least one pair in which both lenslets have a cylindrical shape.