Field tests of a two-laser (4416 A and 6328 A) optical distance-measuring instrument correcting for the atmospheric index of refraction

Abstract

The most recent version of a microwave-modulated two-laser distance-measuring instrument has completed several months of field tests. This instrument was operated almost continuously for about a month over a 5.9-km base line just north of Boulder, Colorado. During the tests the optical path lengths for red and blue varied over 3 cm for the base line, and the corrected distance typically has a σ of <3 mm. The preliminary results of these tests clearly show that this type of instrument can correct a distance measurement taken in 10 sec to better than five parts in 10 million.