Results of lidar modeling based on spatial-angular filtering efficiency criteria are presented. Theiranalysis shows that the low spatial-angular filtering efficiency of traditional visible and near-infraredsystems is an important cause of low signal background-radiation ratio SBR at the photodetector input.The low SBR may be responsible for considerable measurement errors and ensuing the low accuracy ofthe retrieval of atmospheric optical parameters. As shown, the most effective protection against skybackground radiation for groundbased biaxial lidars is the modifying of their angular field according toa spatial-angular filtering efficiency criterion. Some effective approaches to achieve a high filteringefficiency for the receiving system optimization are discussed.