FM-CW radar range measurement at 10-µm wavelength

Wide range distance measurement over 50 km based on highly sensitive detection of the two-photon absorption photocurrent from a Si-APD

“…Optical frequency combs are also applied to precision distance measurement [5]. In addition to these systems, there is a technique using frequency-modulated continuous wave (FMCW) signals [6]. As a fault location system for a long distance optical fiber, optical time domain reflectometry (OTDR) [7] based on the time-of-flight method is widely used.…”

Long range anemometry using a CO2 laser

“…There is considerable current interest [1][2][3][4] in the use of CO2 laser systems for remote measurements of wind velocity. The system discussed here, known as a "co-axial" or "monostatic" system, appears to have the greatest potential for continuous measurements at ranges between 10 m and 1 km.…”