The Design and Evaluation of an Airborne Optical Ice Particle Counter

Abstract

An airborne instrument which provides real-time measurements of the concentrations of ice particles in excess of a certain size has been developed. The instrument utilizes a beam of polarized light and the birefringent nature of ice to detect ice particles but to exclude the counting of water drops no matter how large. Theoretical considerations are discussed which show that the direct use of the birefringence property of ice provides a much larger signal than is possible when only the light scattered from particles is detected. The design, testing and field evaluation of the prototype instrument are discussed.