Patent ID: 7046369

Claim:
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 Δ L=Δp 1 ·λ 1 /(4π); 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 Δ L =(Δ p 1 −Δp 2 )·Λ/(4π) on a basis of a synthetic wavelength defined by a third relation Λ=λ 1 ·λ 2 /(λ 2 −λ 1 ), 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.