Abstract

In precision distance measurement, one of the error sources is the changes of the refractive index of air along the optical path. Two methods are given for estimating the refractive index of air, based on the difference in optical paths between two lasers transmitting at different wavelengths. A long-arm two-color fringe-counting interferometer is developed by using a stabilized 633-nm He-Ne laser and a diode-pumped 1064-nm YAG laser.

© 1991 Optical Society of America