REAL-TIME DOUBLE-EXPOSURE HOLOGRAPHIC PHASE-SHIFTING INTERFEROMETER USING A PHOTOREFRACTIVE CRYSTAL

We present a double exposure interferometer using a Bi12GeO20 crystal as the holographic medium. Once the system is calibrated, the simultan eous acquisition of two phase shifted interferograms allows the real-t ime quantitative measurement of displacements of a scattering object. Experiments are conducted first with a chopped CW argon laser at 514 n m and second with 694 nm nanosecond pulses fi om a ruby laser, At 514 nm the accuracy is lambda/29; it reduces to lambda/15 at 694 nm. (C) 1 997 Published by Elsevier Science B.V.