Fringe Formation in a dual beam symmetric illumination - observation TV holography system: An analysis

摘要

Leendertz dual beam symmetric illumination - normal 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-jplane 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.