Three-color optical range finding

In the known three-wavelength distance-measuring systems two optical wavelengths are used and a microwave is added for air-humidity influence consideration. In our research, which proceeds from results obtained at the National Research Laboratory of Metrology (Japan), the possibility of constructing a three-optical-wavelength ranging system is discussed. We investigate different versions by using a CO(2) laser as the source of the third wavelength. Analysis shows that the three-wavelength system with two lasers (YAG:Nd(3+) laser, which yields first- and second-harmonic radiation, and a CO(2) laser) seems to be optimum. A possible schematic structure of the three-wavelength YAG-CO(2) laser system is given.