Vibration retrieval from time sequences of digital on-line Fresnel holograms

Abstract : This paper proposes an on-line configuration for full-field vibration retrieval at high frame rate. The spatial bandwidth of the recording is optimized by imposing the distance of the Shannon condition at the considered frame rate of the sensor. A negative zoom is designed to adapt the correct optical magnification to fulfill the recording requirements. The illumination of the object is made efficient by the use of a diffractive optical element which provides a concentrated large light spot at the surface of the object. Experimental results demonstrate the suitability of the proposed approach by providing vibration retrieval at 100kHz frame rate.