Influence of reference mirror tilting on the performances of a Michelson-type interference-microscope objective

Abstract

Asymmetric spectroscopic prism of a Michelson white-light interference- microscope objective introduces additional dispersion. The tilt of a reference mirror influences the dispersion and measurement accuracy of a white-light interference-based 3D reconstruction system. In this paper, we first numerically analyzed the performances of a Michelson-type interference-microscope objective by measuring a step structure at different tilt angles of the reference mirror. It showed that the height measurement errors were within the range of ±15nm when the tilt angles were 0°, 0.13°, 0.26°, 0.39° and 0.52 ° , respectively. Finally, a self-designed 5 × interference-microscope objective was used in the white-light 3D measurement system to experimentally demonstrate the influence of reference mirror tilting on the measurement. Both experimental and simulated results are in good agreement, showing that the tilt angle of the reference mirror in a 5× Michelson interference-microscope objective should be less than 0.39° while maintaining a measurement error less than ±15nm. We believe our results can provide a theoretical study for the assembly of reference mirror in a Michelson interference-microscope objective.