A reverse problem of determining layer thicknesses of optical coatings from monochromatic control data
Optical coatings are widely used in modern optics, and the quality of its production is a direct result of optical monitoring - predicting the time of deposition termination from the optical measurements. An inverse problem for determining layer thicknesses from online monitoring data is considered. Solving such a problem will allow to eliminate of systematic errors in deposition and thus improve the quality of coatings produced. In this paper the problem is solved by minimizing the merit function, then this method is compared to the one employed earlier which utilizes the extremum positions to find layer thicknesses. To compare the effectiveness of various methods we simulated the input data, allowing measurement errors and non-stability of deposition. We then eployed the algorithms described on this data and concluded that the best results are achieved by the method of minimizing merit function with signal's numerical derivatives and thus method can be expected to be effective when applied in practice.