System and apparatuses providing laser illumination with reduced or zero speckle

摘要

A system is provided having a multiplexed laser source which combines the outputs of multiple lasers into multiplexed illumination which is then externally modulated to provide output illumination having reduced or zero speckle. Each of the laser sources are turned ON and OFF (gated) in a timed sequence to provide multiplexed illumination having a time-averaged speckle contrast that is lesser than the speckle contrast of the output of any one of the lasers. The output of one or more lasers may also be wavelength multiplexed, where the lasers operate at different wavelengths, and/or polarization multiplexed. An external modulator receives and modulates the multiplexed output in phase and/or modal power distribution to further reduce the speckle in the output of the system. The multiplexed laser source and external modulator can be used as separate apparatuses for reducing speckle in laser illumination.

主权项

1. A system providing laser illumination having reduced or zero speckle comprising:
a plurality of laser sources each providing laser illumination; optics for combining the laser illumination into output illumination; and means for time-multiplexing the operation of the laser sources to provide said output illumination have reduced or zero speckle, wherein said optics comprises one or more optical elements for combining the laser illumination of two different ones of said laser sources each along a first path for inclusion in said output illumination, one or more optical feedback devices in which each of said one or more optical feedback devices optically feeds back light from at least one of said one or more optical elements along a second path different from said first path of the optical element in a direction back to the optical element, in which said optical feedback device is movable to induce one of time-dependent modulation of the temporal modal structure, coherent collapse mode, coherent collapse mode, or swept-frequency mode, in said laser illumination of said two different ones of said laser sources which were combined by said optical element.