Spatial Sampling of the Measuring Volume by the Introduction of Dedicated Apertures in Lidar Systems

Abstract

In ordinary Laser Doppler Anemometry (IDA) light scattered from single particles from two different beams of laser light is mixed coherently on a photodetector surface. The detector current contains information on the velocity of single particles, and various temporal moments of the velocity distribution can be deducted from the readings. LIDAR systems for velocity determination based on infrared sources are usually depending on parametric amplification and will therefore solely probe the longitudinal flow velocity, whereas systems based on lasers emitting visible light are independent of a local oscillator facilitating the probing of all three velocity components in a small measuring volume.