Simulation and observation of infrared piezobirefringent images in diametrically compressed semiconductor disks

Stress-induced birefringence images of diametrically compressed semiconductor disks are examined here. The experimentally observed images are compared with computer-simulated images for (100) and (111) orientation silicon disks. For a (100) oriented sample, the stress-optic coefficient C is found to depend on the position and on the orientation of the load axis with respect to the crystal principal axes. Computed values of C for the (100) orientation silicon varied from 2.0 x 10(-12) to 3.0 x 10(-12) cm(2)/dyn for a diametrically compressed disk with the load being applied at angles of 45 degrees and 75 degrees with respect to one of the crystal principal axes. As expected from the crystal symmetry, C was observed to be a constant for the (111) oriented silicon sample having a value of 2.33 x 10(-12) cm(2)/dyn.