SURFACE INSPECTION APPARATUS AND METHOD

摘要

A simple yet versatile noncontact optical inspection instrument and method for inspection of magnetic disk surfaces for surface defects. The instrument is also capable of discriminating between surface defects and surface contaminants. The instrument is comprised of two identical optical sensors (12) which are located on opposite sides of the disk (16). A carriage (14) supports and translates these sensors (12) along the disk radius while a spindle rotates the disk (16). Both surfaces of the disk (16) are therefore simultaneously scanned in a spiral fashion. The sensor's illumination optics produce a monochromatic focused spot of light which is normally incident upon the disk surface. The sensor uses two collection optics channels which simultaneously detect both the specular reflected light and the diffuse scattered light produced by the disk (16) surface. Both the angle and power of the specular reflected light are measured, while just the power of the diffuse scattered light is measured.