Hi] 3,898,583  Aug. 5, 1975
 LASER STABILIZATION TECHNIQUE
 Inventor: David R. Shuey, Webster, N Y.
 Assignee: Xerox Corporation, Stamford, Conn.
 Filed: Dec. 28, 1973  Appl. No.: 429,246
Related U.S. Application Data
 Continuation-in-part of Ser. No. 239,144, March 29, 1972,abandoned.
 U.S. CI 331/94.5 S; 250/205; 331/109;
331/203; 307/297; 328/167; 330/4.3
 Int. CI HO Is 3/09
 Field of Search 331/94.5, 109,203;
250/205; 307/297; 328/167; 330/4.3
 References Cited
UNITED STATES PATENTS 3,778.791 12/1973 Lewicki et al 331/94.5 X
The output power level of a laser is stabilized at a predetermined set point by a feedback control circuit. The light emitted from one end of a laser is detected and converted into an electrical current by a photodetector. This current is then amplified and converted into a proportional voltage by a buffer amplifier and the resultant voltage is compared to a reference voltage to provide an error signal. The error signal is integrated and fed back to correctively adjust the driving current for the laser, thereby compensating for any tendency of the power level of the light beam emitted from the other end of the laser to drift from a predetermined set point.
7 Claims, 7 Drawing Figures