Tracking the rotation of a birefringent crystal from speckle correlation

The random intensity distribution observed due to the propagation of a coherent beam light through scattering medium is known as speckle pattern. interaction speckles with birefringent crystal, here, YVO4 results in e-ray and o-ray speckles. It that experience an angular shift rotation crystal depends on angle crystal. also found rate different for speckles, independent topological charge incident medium. pattern be same beams. experimentally demonstrated can tracked very accurately from measurement.