TARGET MOVEMENT COMPENSATION FOR LASER SURGICAL SYSTEM

2104380 9215034 PCTABS00015 A system and method for detecting, measuring and correcting for movements of a target (14) in a medical analytic or surgical system (10) utilizes generally the principles of confocal microscopy. A pinhole (42) and photodetector (46) combination is positioned behind optics (12) of a system for delivering an ophthalmic surgery laser beam (24), for example. As in a confocal microscope, the optics are arranged such that a beam waist (44) is formed precisely at the pinhole (42) when the target (14) is in its nominal position. When the target (14) moves from its nominal position in the depth direction, the signal from the pinhole/photodetector combination decreases. The change in the signal can be used to drive the objective lens (12) of the optics so as to move with the moving target (14). Alternatively, the signal can be used to drive the pinhole/photodetector assembly so as to again attain peak signal, in this way allowing the target's shift to be measured.