On optimization of optical parameters of biaxial monostatic CW lidar for atmospheric sensing in the daytime

In a wide range of actively developing lidar technologies, the class of biaxial continuous-wave lidars, sometimes called imaging lidars, is moving forward as one of the promising alternatives to traditional pulsed lidars. It combines the triangulation principle applied to CW lidars with spatially-resolved measurements and modern photonic technologies using diode lasers and image processing based on matrix or linear-array detectors. To ensure undistorted reception and further processing of echo-signals and images as well as reliable restoration of the range profiles of the atmospheric parameters under conditions of intense background radiation of the daytime sky, it is especially important to take into account the specific originality of imaging lidars, which distinguishes this class of instruments from traditional systems. These are the specific features of their spatial selectivity formation based on a reasonable choice of both lidar instrument and array detector parameters, the exposure conditions and physical properties of the background radiation with proper consideration of the propagation medium, etc. The performed analysis of the imaging lidar focuses attention on the distorting effect of the uneven power of external background coming to single micro-cells of the 1D- or 2D-arrays. In a number of atmospheric-optical situations and with wide variations of optical and design parameters of lidar, there may be noticeable limitations in the measurement accuracy of echo-signals caused by incorrect consideration of the inhomogeneous background load of detector cells and subsequent distortion of results of the atmospheric range profiles retrieval. The approach proposed is aimed at paying attention and overcoming some of these limitations.