An improved interferometric measuring system wherein the system projects a first beam of light at a first measurement wavelength along a reference path to a reference reflector and a second beam of light at a second measurement wavelength along a measurement path to a measurement reflector, and determines...http://www.google.de/patents/US5404222?utm_source=gb-gplus-sharePatent US5404222 - Interferametric measuring system with air turbulence compensation
