Optimization design and performance analysis of quaternion spatial pseudo-depolarizer

In this study, to improve the uniformity of transmission light intensity of depolarizer, we present an optimal design of the quaternion space pseudo-depolarizer consisting of four wedge crystals. By designing the optical axis and wedge angle of each crystals, the square distribution of the output spot is realized. The mathematical expression of the degree of depolarization is obtained using the light wave superposition method. Theoretical analysis shows that the new type of depolarizer can optimize the intensity distribution of the emergent light field when the depolarizer wedge angle is sufficiently large, and it can realize the perfect depolarization of monochromatic linear polarized light. A samples of the quartz crystal material are developed and tested using lasers of 405 nm and 670 nm wavelengths. The degree of depolarization is observed to be 99% for any azimuth angle, whereas the angle of field of view is −10°–10°.