Phase evaluation of speckle patterns during continuous deformation by use of phase-shifting speckle interferometry

A method far measurement of continuous displacements that uses phase-shifti ng speckle interferometry is presented. The initial random phase of the spe ckle pattern is evaluated by phase shifting before deformation. The changin g phase thereafter is evaluated from only one image at a time by a least-sq uares algorithm. The technique can be used for measuring transients and oth er dynamic events, heat expansion as well as other phenomena, for which it is difficult to accomplish phase shifting during deformation. Theory along with computer simulations and experimental results are described. (C) 2000 Optical Society of America OCIS codes: 120.6160, 120.5050, 180.5060, 090.28 80.