METHOD AND APPARATUS FOR SURFACE ROUGHNESS MEASUREMENT USING LASER DIFFRACTION PATTERN

A non-contact visual system for analyzing surface roughness directs onto the surface of a workpiece a laser beam which is reflected from the surface with a diffraction pattern. The image of the reflected diffraction pattern is captured on a mirror and reflected onto a display screen, and this displayed image is converted into analog signals which, in turn, are converted into digital data. The intensity of the captured image is determined from the digital data, and the data on the determined intensity of the captured image are compared with data on intensity from calibrated standards of surface roughness. From this comparison, the surface roughness of the workpiece is determined. The preferred technique uses a rasterizing graphics adapter for converting the output of a video camera into the digital signals and only pixels above a predetermined brightness value are utilized.