TrackerScan™

An Integrated Non-Imaging Workpiece Tracker and Beam Steerer for Laser Making Systems

Physical Sciences Inc. (PSI) has developed a mechanism that enables a laser marking system to automatically follow rapid, random movement of a workpiece. This patented device automatically drives galvanometer-mounted mirrors as fast as 200 degrees per second to compensate for workpiece motion.

PSI's workpiece follower combines the optical technique of confocal reflectometry with the electronic technique of phase-sensitive detection. Unlike many other tracking systems, it does not rely on image processing techniques, which are limited by image acquisition and processing speed. Instead, it utilizes a high-bandwidth feedback signal derived from the light of a low-power "tracking beam" scattered off the workpiece surface. The tracking beam and the marking system's laser beam are both directed onto the workpiece by a shared set of galvanometer-mounted mirrors. The feedback signal continually adjusts the mirror orientations to lock the tracking beam to a target on the workpiece. Because the marking beam shares the same mirror surfaces, it also follows the workpiece motion. Relative movements of the marking beam, which create the laser mark on the workpiece, are unaffected by the workpiece follower. The result is that the laser marking beam always registers in the correct spot on the workpiece, despite any workpiece movement.

Simplified illustration of TrackerScan&tm;

Steven J. Davis Physical Sciences Inc. 20 New England Business Center Andover, MA 01810-1077 Telephone: (978) 689-0003 Fax: (978) 689-3232 sdavis@psicorp.com