Patent ID: 7046369
Filing Date: 2006-05-16
Classification: G01B

Abstract:
1. An interferometric measuring method for measuring one of a shape of an object surface and a distance to an object surface, comprising: generating a light; frequency-modulating the light; conducting a first portion of the light to the object surface; conducting a second portion of the light to a reference surface; bringing a first reflected light from the object surface and a second reflected light from the reference surface to interference; conducting the first reflected light and the second reflected light to a photodetector; and evaluating a phase of a photodector signal in at least two different instants with wavelengths that correspond on a basis of the frequency modulation determining a first phase difference at a first instant corresponding to a first wavelength; undertaking a measurement in accordance with a first relation determining a second phase difference at a second instant corresponding to a second wavelength; and taking a measurement on the object surface in accordance with a second relation on a basis of a synthetic wavelength defined by a third relation wherein Δp 1 represents the first phase difference, Δp 2 represents the second phase difference, λ 1 represents the first wavelength, λ 2 represents the second wavelength, Λ represents the synthetic wavelength, and ΔL represents a change in distance to the object surface.