Sparkle phenomenon

Propagation of a laser beam of sufficiently high power density along a path contaminated by suspended particulate matter creates an impressive visible effect due to the burning of the particles. This effect, appropriately named sparkle, may seriously hamper attempts to utilize the beam path for receiving the low level object return signal required in the operation of certain closed loop control systems. This paper analyzes the sparkle phenomenon by examining the particle energy capture and loss mechanism and developing an event temperature history. Specifically, the observed event duration is explained in terms of the boiling point front velocity through the particle, and expressions for the particle motion in the beam are developed.