Improving the Accuracy of Interferometer Testing with Absolute Surface Calibration And Power Spectral Density Analysis

Abstract

A novel absolute surface calibration method for interferometer testing based on power spectral density analysis has been proposed. The method involves obtaining the loss of signal at different frequencies as a function of various rotation angles by signal analysis to choose the rotation angle for calibration. A model is developed to evaluate the calibration method by creating random surface shapes based on the PSD. Using this algorithm, the precision of the absolute testing method during the testing process exceeds 0.28%. Error propagation during the experimental process, such as testing optic clamping, positional deviation, and environmental disturbances, are calibrated. Ultimately, the absolute detection test results are verified using high-precision flat mirrors. The experimental result indicates an RMS (Root Mean Square) of 4.275nm, 4.263nm, and 4.265nm in different rotation angle, and the calibrated result shows an RMS of 4.880nm. The similarity in the distribution of surface map validates the feasibility of the calibration method.

Keywords: Interferometer testing, Absolute measurement, Surface error metrology, Power Spectral Density