University of California

William N Partlo

William G Oldham

A train of coherent laser output pulses with reduced speckle is generated by providing laser pulses having a first polarization and a coherence length, splitting each pulse in the input laser pulses to provide a first pulse train including a first series of output pulses of the first polarization in output pulses and a second pulse train, and rotating polarization and delaying the second pulse train. The second pulse train is then split to provide a second series of output pulses having a different polarization than the first series of output pulses and a third series of output pulses having a delay length greater than the laser coherence length thereby providing a train of coherent laser output pulses including the first series of output pulses interleaved with the second series of output pulses and the third series of output pulses. The train of coherent laser output pulses can again be split and delayed with polarization rotation to generate a second train of coherent laser output pulses. To further reduce speckle in the generated train of coherent laser output pulses, the optics for delaying and rotating the polarization can be so arranged that each pulse in the train exits the system in a slightly different position and at a slight different angle whereby the speckle pattern produced by the interaction of the beam with scatterers is uncorrelated.

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Berkeley, CA, United States of America

William N Partlo