Abstract

The use of multiple wavelengths in an interferometer to measure absolute distance is well established.¹ We previously reported² on such measurements over distances up to 25 m using a CO₂ laser source. At longer distances, the systematic variations in the laser frequency, which produce fluctuations in the interferometer phase, become large enough to cause ambiguities in the algorithms used to calculate the distance in terms of synthetic wavelengths.¹

© 1989 Optical Society of America