| 主权项 |
1. A measuring apparatus comprising:
an optical frequency comb source configured to emit an optical frequency comb in which a plurality of frequency components are arranged at equal frequency intervals; a beam splitter configured to split a beam emitted from the optical frequency comb source into a test beam to be irradiated onto a test surface and a reference beam to be irradiated onto a reference surface; an optical path difference changing element configured to change an optical path difference between the reference beam and the test beam; an image sensor configured to capture an interference pattern formed by interference between the test beam and the reference beam; and an analyzer configured to calculate a position of the test surface based upon a signal of the interference pattern captured while the optical path difference is being changed by the optical path difference changing element, wherein the analyzer calculates the position of the test surface by utilizing the following expression:H(x,y)=Λ2(N(x,y)+ψ(x,y)) where H(x,y) is the position of the test surface, Λ is a synthetic wavelength obtained by dividing a light speed by the frequency interval of the optical frequency comb source, N(x,y) is an interference order, and ψ(x,y) is a fraction phase corresponding to a phase difference of the signal of the interference pattern for each frequency interval, and wherein the analyzer determines the interference order by a phase connection of the fraction phase. |
