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A general problem in optical metrology is to measure a deformation field when this field is added to a translation or a rotational motion. Methods like Speckle Photography (SP) do handle large rigid body motions but the results might be of too poor accuracy to resolve the deformation field. Interferometric methods on the other hand might measure the deformation field but the bulk motion makes the fringes disappear. By combining Digital Speckle Photography, DSP, (also called digital correlation) with Speckle Interferometry, SI, (also called ESPI, DSPI, TV holography, pulsed TV holography) or with shearography (TV shearography) such measuring situations can be mastered.

Leendertz dual beam symmetric illuminationnormal observation arrangement is widely employed for real time evaluation of in-plane displacement components as well as surface shape. Instead of observing along the optical axis, we have examined the Leendertz arrangement by observing the scattered light along the direction of illumination beams, and imaged as two separate images onto a photo sensor of a CCD camera. In this paper, we will show that the interference between the speckle fields generated from one of the illuminating beams with the specular reflection speckle fields from the second illuminating beam, is responsible for fringe formation along the directions of observation. The interferometer is a combination of two channels; each of which senses independently and simultaneously the information pertaining to either the in-plane displacement component of a deformation vector, or surface relief variation of a three dimensional object. A summary of possible information that can be extracted from the present arrangement is also highlighted. Experimental results using a four-frame phase shifting technique are illustrated.

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