Interferometrische Wegmessung mit automatischer Brechzahlkompensation

Fluctuations of the refractive index of air causes nowadays the largest errors in high precise interferometric displacement measuring systems. We present in this paper a new method for compensating these influences by tuning the optical frequency of the laser. Variing laser temperature and current regulates the frequency (wavelength) of a GaAlAs-semiconductor laser in such a manner, that the wavelength in air is constant.