Wavelength selection for long range laser vibration sensing

The possibility of using remote laser vibration measurement for target identification and other purposes continues to attract interest and research in several countries. In the past, the only available laser technology capable of providing, in a compact transmitter package, the required single-frequency laser power for long range laser vibration sensing against unenhanced targets, was CO, laser technology. Recent developments in laser transmitter technology have opened up the possibility of using solid state lasers operating in the eyesafe region (wavelength > 1.4 mu m) as the transmitter in future long range laser vibration sensors. This paper discusses some of the factors which must be considered in selecting a laser transmitter source for such systems. These factors include vibration measurement sensitivity at the required operating ranges, atmospheric extinction, pointing and tracking requirements, atmospheric turbulence, and eye safety. We conclude that selection of the operating wavelength and transmitter technology must be tailored to each individual application, and should not be presumed to be a foregone conclusion.