Optical EngineeringHigh-speed laser speckle photography. Part 2: rotating mirror camera control system and applications
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A rotating mirror camera and pulsed ruby laser have been combined to record laser speckle photographs at framing rates in the range of 105 to 106 frames/s. The laser is repetitively Q-switched by means of a Pockels cell, which is controlled by photodetectors inside the camera. This allows well-correlated , double-exposu re speckle photographs to be recorded on two separate runs of the camera. The photographs are analyzed by an automated image processing system to give whole-field displacement data with submicron accuracy. The illustrations show the dynamic displacement field in polymethyl methacrylate due to solid particle impact. The camera/laser system has potential applications for other stress analysis techniques, such as photoelasticity, the method of caustics, and moiré interferometry.