Heterodyne Laser Microscope for Enhanced Detection and Sizing of Defects in Moving Objects
Original Publication Date: 1987-Jun-01
Included in the Prior Art Database: 2005-Feb-01
A heterodyne laser microscope which is applicable to the surface profiling/defect detection of a moving object by heterodyning the incident light with the scattered light is described. A heterodyne laser microscope (HLM) is shown in the figure which is operable for imaging defects in a moving object, such as a rotating magnetic disk, for example. A continuous single-frequency and single- mode GaAs diode laser 1 is mounted on a radial arm (not shown) so that the focused laser spot 3 can be moved to any radial position on the rotating disk 2. Since the disk is of good smoothness and optical finish generally, the re-emitted light from the disk is mainly in the specular direction, i.e., in the normal direction, since the incident beam is normal.