interferometric measurement of ebenenabstu00e4nden with subnanometer accuracy

摘要

The invention relates to a method for the interferometric determination of the change in the optical separation between two planes in a sample, on transferring from a first to a second measurement point on the sample, whereby the sample is illuminated with light of a large bandwidth and the sample is embodied to be at least partly transparent to the light and the planes to be partly reflecting. The method comprises the steps: spectral splitting of the interference in the light beams reflected from the planes at both measurement points, determination of the modulation frequencies and phase positions of the spectrograms and generation of the differences for said results, drawing an inference of a first value for the optical separation change of the planes from the difference of the modulation frequencies alone and calculation of a second more accurate value for the optical separation change from the first value, by taking into account the phase difference.