US 6,982,821 B2
Optical beam position active sensing using satellite beams
David L. Hecht, Palo Alto, Calif. (US)
Assigned to Palo Alto Research Center Incorporated, Palo Alto, Calif. (US)
Filed on May 22, 2003, as Appl. No. 10/443,725.
Prior Publication US 2004/0233510 A1, Nov. 25, 2004
Int. Cl. G02F 1/33 (2006.01)
U.S. Cl. 359—305 49 Claims
OG exemplary drawing
 
1. A beam position sensing system comprising:
a beam source configured to generate a directed beam;
a satellite beam generator aligned to receive the directed beam and to transmit a main beam and generate a pair of symmetric satellite beams having time-varying deflection angles from the main beam;
a first detector arrangement positioned to detect a first satellite beam of the pair of satellite beams and generate a first detector signal; and
a second detector arrangement positioned to detect a second satellite beam of the pair of satellite beams and generate a second detector signal,
wherein the first detector signal and the second detector signal are used to determine an absolute position of the main beam.