Methods and apparatus for calculating and maintaining an optimal sample position in an interferometric microscope

Abstract

There is provided a method of calculating a temperature corrected sample position in an interferometric microscope, the method comprising projecting an autofocus beam onto the sample location to form a reflected ring of radiation, detecting an uncalibrated radius. R, of a peak of the annulus of the reflected ring which indicates an uncalibrated sample position, detecting one or more of the width of the annulus or an intensity of the annulus and calculating a calibrated radius Rnorm using at least one of the width of the annulus or the intensity of the annulus to determine the temperature dependent corrected sample position.

Dependencies are inferred from the claim text.