SEPARATION OF THE INFLUENCE OF INPLANE DISPLACEMENT IN MULTIAPERTURE SPECKLE SHEAR INTERFEROMETRY

An imaging system with its aperture fully open or with a multiaperture mask in front has been used for carrying out speckle shear interferom etry. The shearing is achieved by installing shear elements in front o f the imaging system. The multiaperture configuration has built-in in- plane displacement sensitivity, and hence shear fringes obtained from multiaperture shear interferometer always carry the in-plane displacem ent contribution. This problem does not arise when the full aperture o f the lens is used. A three-aperture speckle shear interferometric tec hnique is introduced here to separate the in-plane displacement and sl ope contributions from the shear interferogram. Detailed theoretical a nd experimental results are presented.