Determination of 3-D stress by optical tensor field tomography

A novel method for measuring arbitrary three-dimensional states of mechanical stress in photoelastic models is presented. The theory of tensor field tomography is described and an iterative reconstruction algorithm is given, which processes the projection data received by illuminating the model for several orientations. The method generally works well for limited amount of stress, which is demonstrated by simulations. An experimental setup is presented for measuring the required projection data. It is a combination of an extended Mach-Zehnder interferometer and a polariscope.