Patent ID: 8605289

Claim:
A method for interferometry comprising: producing an electromagnetic measurement signal; splitting the measurement signal into a scanning beam component and a reference beam component; illuminating at least one object point with at least a portion of the scanning beam component; producing an interference signal by superimposition of a component of the scanning beam component that has been reflected from the at least one object point with the reference beam component, wherein that portion of the scanning beam component in the interference signal which has been reflected from the at least one object point has an optical path-length difference x_O, which depends on the position of the object point, relative to the reference beam component, wherein the measurement signal is produced with a frequency comb spectrum with the same frequency comb intervals Δf_Signal of the individual frequency components, and/or wherein the interference signal is filtered by means of a frequency comb filter such that the filtered interference signal now has only a frequency comb spectrum with the same frequency comb intervals Δf_Signal of the individual frequency components; and wherein the method furthermore comprises: carrying out a first scanning process such that the optical path-length difference x_O or the frequency comb intervals Δf_Signal in the frequency comb spectrum is varied continuously; carrying out a second scanning process repeatedly during the first scanning process, such that the frequency comb interval Δf_Signal or the optical path-length difference x_O is varied continuously so that a change in the frequency comb interval Δf_Signal or the continuous change in the quotient c/x_O of the speed of light c and the optical path-length difference x_O resulting from the continuous variation of the path-length difference x_O corresponds in its mathematical sign at least at times to the continuous change of the frequency comb intervals Δf_Signal caused by the first scanning process and such that the frequency comb intervals Δf_Signal corresponds at least at times to an integer multiple of the quotient c/x_O; and detecting an intensity and/or of an intensity change in the interference signal for a multiplicity of frequency comb intervals Δf_Signal and/or for a multiplicity of optical path-length differences x_O.