LIDAR (Light Radar) is one approach to measuring the distance to soft targets, such as airborne particulates. The soft target is illuminated by a laser, some light is reflected and collected by a telescope. The time delay between transmission of the illumination pulse and receipt of the backscattered light reveals the range to the target. By illuminating the target at multiple wavelengths (Differential Absorption LIDAR, "DIAL") it is possible to determine not only how far away it is, but also to infer its chemical and physical properties as well as the properties of the atmosphere along the line-of-sight. PSI is developing DIAL systems based on mid-IR quantum cascade lasers to characterize liquids on surfaces, atmospheric chemical vapor plumes, and aerosol clouds.

LIDAR Publications		Laser Sources and Applications Research Area Chemical Sciences Research Area Photonics Enterprise Sensors and Materials Enterprise MWGS-1: Multi-Wavelength Gas Sensor