04634880 is referenced by 30 patents and cites 2 patents.

A confocal optical imaging system includes a laser for producing a linearly polarized beam which is transmitted through the optical elements of the system, focused on a small spot on the target, and reflected back through the optical elements to a photodetector where the reflectance from the spot is determined. The optical elements include a pinhole plate for restricting the size of the transmitted and reflected beams which plate, along with other of the optical elements, can produce unwanted reflections adding optical noise to the reflected beam from the target. A retardation plate between the pinhole plate and the target alters the polarization of the transmitted beam relative to the reflected beam so that a polarizer will discriminate between the true reflected beam signal and the unwanted reflections to thereby improve the signal-to-noise ratio at the photodetector.

Title
Confocal optical imaging system with improved signal-to-noise ratio
Application Number
725082
Publication Number
4634880
Application Date
February 19, 1986
Publication Date
January 6, 1987
Inventor
Ian R Smith
Los Gatos
CA, US
Simon D Bennett
Los Gatos
CA, US
James T Lindow
Saratoga
CA, US
Agent
Robert S Kelly
Assignee
SiScan Systems
CA, US
IPC
G01N 21/88
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