Bistatic imaging lidar technique for upper atmospheric studies

The bistatic imaging lidar technique is fundamentally different from traditional monostatic lidar techniques. The vertical density of an atmospheric layer, such as the mesospheric sodium layer, is measured by imaging an illuminated spot within the layer. The spot is illuminated with a laser and imaged with a telescope in a bistatic configuration. Profiles through the image contain information about the vertical structure of the layer as well as the laser beam cross section. These profiles can be interpreted as the output of a linear filter having the density profile of the layer as input and an impulse response which is related to the laser beam cross section and imaging geometry. The theoretical vertical resolution can be quantified in terms of laser beamwidth and separation distance between the laser and telescope. Theoretical analysis of the technique and experimental data verifying the feasibility and basic performance of the technique are presented.