US 6,982,790 B1 | ||
Coherent imaging in turbid media | ||
Meir Gershenson, Panama City, Fla. (US) | ||
Assigned to The United States of America as represented by the Secretary of the Navy, Washington, D.C. (US) | ||
Filed on Jan. 27, 1998, as Appl. No. 9/14,011. | ||
Int. Cl. G01B 9/02 (2006.01) |
U.S. Cl. 356—349 | 6 Claims |
1. A system for forming an image of an object in a turbid medium, comprising:
a laser light source for producing a coherent light beam of a selected frequency;
a lens arranged to receive the coherent light beam output from the laser;
a beamsplitter arranged to receive the coherent light beam that has passed through the lens and produce a reference beam directed
along a reference optical path and a signal beam that is directed along a signal optical path to impinge upon the object in
the turbid medium and reflect back toward the beamsplitter;
means for modulating the reference beam;
a mirror arranged to reflect the reference beam back toward the beamsplitter for combination with the signal beam to produce
an output optical signal, the output optical signal having a beat frequency when the signal beam and the modulated reference
beam have equal optical path lengths;
a photodetector arranged to received the output optical signal from the beamsplitter; and
a heterodyne detector connected to the photodetector and arranged to produce a beat signal when the first and second optical
paths have matching lengths.
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