COMPUTER SIMULATIONS OF ERRORS OF INDIRECT SPECTRAL INSPECTION OF THE LAYER THICKNESS OF MULTILAYER OPTICAL COATINGS
Results of studying the errors of indirect inspection by means of computer simulations are reported. The inspection method is based on measuring spectra of reflection from additional reference substrates in a wide spectral range. Special software (Deposition Control Simulator) is developed, which allows one to estimate the influence of the inspection system parameters (noise of the photodetector array, operating spectral range of the spectrometer and errors of its calibration in terms of wavelengths, drift of the radiation source intensity, and errors in the refractive index of deposited materials) on the random and systematic errors of deposited layer thickness measurements. The direct and inverse problems of multilayer coatings are solved by using the OptiReOpt library. Curves of the random and systematic errors of measurements of the deposited layer thickness as functions of the layer thickness are presented for various values of the system parameters. Recommendations are given on using the indirect inspection method for the purpose of reducing the layer thickness measurement error.