Measurements of absolute distances to 25 m by multiwavelength CO(2) laser interferometry.
The development of a CO(2) laser, tunable over six rotational lines, and its use in a heterodyne interferometer for absolute distance measurements are described. Measurements were made using a variety of difference frequencies enabling distances up to 25 m to be measured to an accuracy limited by refractive-index uncertainties. An evaluation of the device using comparative measurements against a commercial laser interferometer over a common path gave an ultimate accuracy of +/-5 microm.
Walsh
C J
CJ