An optical system is designed and fabricated on the basis of the target scattering characteristics and the edge tracking concept. This system is the optical head of a frequency modualated continous wave CO2 laser radar in which only a single mode CO2 laser is used. Using a collimator tube, the tested minimum light speckle on the focus plane is 50 μm in diameter. The acceptable error signals are engendered when a slender laser beam of 0.12 mrad angular divergence is directed on the diffuse target edge. The backscattered signals from building at 7.8 km are obtained with a fairly good SNR when the laser output is about 5W.