Method and apparatus for reducing laser speckle
First Claim
1. An apparatus for reducing laser speckle, comprising:
- a light guide having an entrance face and an exit face;
a first mirror at the entrance face of the light guide, the first mirror having a aperture formed therein for admitting a predetermined input laser beam into the light guide; and
a second, partially-reflective mirror at the exit face of the light guide, wherein the second mirror is capable of passing some of the laser beam incident thereon and reflecting some of the laser beam incident thereon back into the light guide toward the first mirror.
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Accused Products
Abstract
An apparatus and method for reducing speckle of a laser beam is disclosed. The apparatus includes a light guide, a highly reflective mirror at the input face of the light guide and a partially reflective mirror at the exit face of the light guide. A coherent laser beam is introduced into the light guide through a clear aperture in the highly reflective mirror. Within the light guide, the laser beam gets separated into plural, successive beamlets having different phase shifts, different polarization states and/or path length differences equal to or greater than the coherence length of the laser beam. The beamlets exit the light guide through the partially reflective mirror to provide output laser light with reduced speckle. The light guide can be either a solid light pipe of transmissive material or a hollow tunnel with reflective interior sidewalls.
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Citations
28 Claims
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1. An apparatus for reducing laser speckle, comprising:
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a light guide having an entrance face and an exit face; a first mirror at the entrance face of the light guide, the first mirror having a aperture formed therein for admitting a predetermined input laser beam into the light guide; and a second, partially-reflective mirror at the exit face of the light guide, wherein the second mirror is capable of passing some of the laser beam incident thereon and reflecting some of the laser beam incident thereon back into the light guide toward the first mirror. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A method for reducing laser speckle, comprising:
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providing a light guide having an entrance face and an exit face; providing a first mirror at the entrance face of the light guide, the first mirror having a clear aperture formed therein; providing a second, partially-reflective mirror at the exit face of the light guide, wherein the distance between the first and second mirrors is at least one-half the coherence length of a predetermined input laser beam, the second mirror capable of passing some of the laser beam incident thereon and reflecting some of the laser beam incident thereon back into the light guide toward the first mirror; and directing the predetermined input laser beam into the clear aperture, whereby output laser light with reduced speckle exits from the partially-reflective mirror. - View Dependent Claims (23, 24, 25, 26, 27, 28)
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Specification