Patent ID: 7193765
Filing Date: 2007-03-20
Classification: G02B,H04N

Abstract:
1. An apparatus for reducing laser speckle and interference patterns in a laser projector display, when using a laser projector having a spatial light modulator (SLM) with a defined pixel rate, comprising: a continuous wave laser having a laser output defining an optical path to be split into multiple optical paths; a beam combiner positioned optically down field from the continuous wave laser for recombining the multiple optical paths; a first half wave plate placed in an optical path incident to the laser output and configured to polarize the laser output to be s-polarized with respect to the beam combiner; a first polarization-independent beam splitter optically positioned and configured to divide the laser output of the continuous wave laser into a first laser beam and a second laser beam; a phase modulator optically positioned and configured to oscillate a phase of the second laser beam with an amplitude sufficient to create a phase delay of an odd integer multiple of approximately half a wavelength of the laser output and at a frequency at least twice that of the pixel rate of the SLM; a second polarization-independent beam splitter optically positioned and configured to reflect approximately half of the first laser beam and half of a phase modulated second laser beam and to transmit approximately half of the first laser beam and half of the phase modulated second laser beam to produce third and fourth laser beams, each of the third and fourth laser beams comprising approximately half of the first laser beam and approximately half of the phase modulated second laser beam; a second half wave plate optically positioned and configured to polarize the fourth laser beam to be p-polarized with respect to the beam combiner; and the beam combiner configured to combine the s-polarized third laser beam and the p-polarized fourth laser beam into a fifth laser beam.