Wideband monitoring of optical coatings with deposition error correction

The manufacture of complex multilayers requires the maker to have a satisfactory monitoring system. The monitoring system can control accuracy not only in optical thicknesses of nonquarterwave layers but can also compensate deposition errors in real-time in order to secure a stable monitoring and eventually to achieve the desired optical performance. In this paper, a computer controlled apparatus for monitoring of wideband optical coatings is described. A method, based on performance measurements during the monitoring of a layer in situ, has been developed to determine the actual refractive index and thickness of the layer in vacuo. The method can be used as a means of detecting deposition errors.