HIGH PRECISION LASER MONITOR FOR MANUFACTURE OF OPTICAL COATINGS AND METHOD FOR ITS USE

摘要

A high precision laser monitor (10) for manufacture of optical coatings and method for its use. A laser (14) produces a beam of light which is divided into a reference portion and a second portion. First and second gain-programmable preamplifiers (22) receive the reference signal and the detector signal, respectively, and produce respective first and second output signals. A comparator compares the first and second output signals and produce a comparison signal. The computer (26) operates to drive the comparison signal toward zero by controlling first and second gain-amplifiers control signals and produces a transmission monitoring signal by analyzing the changes in the first and second gain control signals needed to drive the comparison signal toward zero. The computer (26) uses the transmission monitoring signal to control the coating depositor to achieve the desired thickness for each layer of the coating.