Two-Laser Optical Distance-Measuring Instrument that Corrects for the Atmospheric Index of Refraction

Abstract

The Wave Propagation Laboratory of the Environmental Research Laboratories of the National Oceanic and Atmospheric Administration has been engaged in the development of dual-wavelength, optical distance-measuring instruments. Recently a new generation of this type of high-accuracy instrument has been completed. Preliminary testing of the new instrument indicates that the original goal of the project, accuracy of better than one part in a million over distances of 5–10 km using averaging times of less than 1 min, is being met. This paper describes the instrument and preliminary test results.