Digital holographic measurement system for high-speed three-dimensional deformation measurements

Abstract

We present a measurement system based on digital holography and two light sources, which is suitable for high speed three-dimensional deformation measurements. Circular in-plane sensitivity is achieved using a diffractive optical element (DOE) for illumination in combination with two laser sources creating two holograms on one camera frame. Both holograms are separated using two different spatial carrier frequencies. As the two lasers are illuminating the object under a different angle it is possible to calculate in-plane and out-of-plane deformation out of two camera frames and the resulting four holograms. The system may be applied e.g. for high speed deformation measurements or the measurement of residual stress. Besides first measurement results obtained with the holographic device and a comparison to results of an already existing measurement system based on digital speckle pattern interferometry (DSPI) are presented.