Non-contact thickness determn. - by moving focusing lens for laser beam

摘要

A non-contact method of determining the thickness of transparent materials is based on focusing a laser beam on the material by moving an adjustable lens. The reflected beam is deflected towards a focus detector, and a displacement measurement determines the position of the upper and lower material surfaces at which they coincide with the laser beam focus. ADVANTAGE - This can be used to determine the thickness even of a specimen which is only accessible from one side.