Lea, T. K. | Search NASA

NASA NTRS1988

Infrared retroreflecting lidar calibration target

A lightweight flexible lidar calibration target has been fabricated for use at 10.6 microns. The biconical reflectance of the target was kept low to reduce the possiblity of detector saturation. The target has been designed so that the biconical reflectance is nearly independent of the target orientation over the range of angles of incidence + or - 60 deg, causing the calibration properties to be independent of target orientation. The present target is relatively inexpensive to construct.

Lea, T. K.↗

NASA NTRS1986

Correction function in the Lidar equation and the solution techniques for CO2 Lidar date reduction

For lidar systems with long laser pulses the unusual behavior of the near-range signals causes serious difficulties and large errors in reduction. The commonly used lidar equation is no longer applicable since the convolution of the laser pulse with the atmospheric parameter distributions should be taken into account. It is important to give more insight into this problem and find the solution techniques. Starting from the original equation, a general form is suggested for the single scattering lidar equation where a correction function Cr is introduced. The correction Function Cr(R) derived from the original equation indicates the departure from the normal lidar equation. Examples of Cr(R) for a coaxial CO2 lidar system are presented. The Differential Absorption Lidar (DIAL) errors caused by the differences of Cr(R) for H2O measurements are plotted against height.

Zhao, Y.↗