Turbulent Lidar: I−Design

Abstract

Two designs of a laser radar system based on the backscatter amplification effect (BSA) are suggested. The system is a micropulse aerosol lidar with two receiving channels, one of which records an increase in the lidar returns at the laser beam axis as the atmospheric turbulence intensifies. The second channel does not respond to the BSA and is required for calibration. The BSA effect manifests itself in a narrow spatial region around the laser beam axis; so, the receiver aperture should be small enough and comparable with the Fresnel zone. The creation of the turbulent lidar became possible with the advent of compact diode-pumped micropulsed lasers with high pulse repetition rates. The lidar is intended for continuous long-term unattended operation. It is eye-safe. Two designs of the turbulent lidar based on an afocal Mersenne telescope (mirror collimator) are suggested. BSA-2 and BSA-3 turbulent lidars are described. An algorithm is suggested for retrieval of the structure parameter of optical turbulence C_n² from lidar data based on the Vorob’ev’s approximation for a statistically homogeneous turbulent medium.