A DESENSITIZED DISPLACEMENT INTERFEROMETER APPLIED TO IMPACT RECOVERYEXPERIMENTS

A variable sensitivity displacement interferometer (VSDI) used to moni tor both normal and in-plane particle displacements in stress wave pro pagation experiments is introduced. The general system consists of two interferometers working in tandem. Normally reflected light is interf ered with each of two symmetrically diffracted light beams generated b y the specimen rear surface. In cases where the surface motion simulta neously exhibits both in-plane and normal displacements, the fringes r epresent a linear combination of the longitudinal and transverse compo nents of motion. Decoupling of the normal and in-plane displacement hi stories can be achieved through a linear combination of the two VSDI r ecords. The variable sensitivity feature of the VSDI greatly desensiti zes normal displacement measurements and is particularly well suited f or wave propagation studies, Experimental results are presented which demonstrate the application of this technique to monitoring particle m otion histories in pressure-shear recovery experiments. (C) 1996 Ameri can Institute of Physics.