Distance measuring interferometric instrument - has molecular laser for measuring distances of several hundred metres

摘要

A molecular laser (1) is used in conjunction with an optical adaptation unit (2) and a semi-transparent mirror (4), which divides the light beam (3) into a first beam (5) in a reference direction and a second beam (7) in a measuring direction. A reflector (6) is placed at a known distance for reflecting the first beam (9) and another reflector (8) placed at the distance to be measured reflects the second beam (11). A detector (12) measures the phase difference between the two reflected beams (9, 11) and actuates a device (25) which drives the reflector (6) to null out the difference between the two reflected beams (9, 11). A calculator (14) is used to determine the distance to be measured from the signal output of the reflector actuating device (25).