We describe a phase-shifting out-of-plane speckle interferometer operating at 1 kHz for studying dynamic events. The system is based on a Pockels cell that is synchronized to a high-speed video camera to ensure that the phase shifting occurs between frames. Phase extraction is performed by use of a standard four-frame algorithm, and temporal phase unwrapping allows sequences of several hundred absolute (rather than relative) displacement maps to be obtained fully automatically. The maximum theoretical surface velocity of 67 μm s−1 is a factor of 40 greater than can be achieved with a speckle interferometer based on a conventional video camera. We test the system using a target that is displaced with constant speed in a direction normal to its surface by means of a piezoelectric transducer. The system’s performance in a practical situation is illustrated with measurements on a thin plate undergoing out-of-plane deformation.
© 1999 Optical Society of America
[Optical Society of America ]
(120.2650) Instrumentation, measurement, and metrology : Fringe analysis
(120.5050) Instrumentation, measurement, and metrology : Phase measurement
(120.6160) Instrumentation, measurement, and metrology : Speckle interferometry
(120.7280) Instrumentation, measurement, and metrology : Vibration analysis
Jonathan M. Huntley, Guillermo H. Kaufmann, and David Kerr, "Phase-Shifted Dynamic Speckle Pattern Interferometry at 1 kHz," Appl. Opt. 38, 6556-6563 (1999)