Focal performance analysis of closed-boundary cylindrical microlenses made of uniaxial crystal

Abstract

In this paper, we investigate the focal performance of closed-boundary cylindrical microlenses (CBCMs) made of anisotropic uniaxial crystal based on rigorous electromagnetic theory and the boundary element method (BEM). For both TE and TM polarizations, focal performances of the anisotropic CBCMs with different f-numbers are studied in detail. The influence of illumination type on focal performances of CBCMs are also considered. Several focal performance quantities, such as the real focal position, the focal spot size, the diffraction efficiency and the normalized transmitted power, are presented. Numerical results indicate that the focal performance of anisotropic CBCMs made of uniaxial crystal differs greatly in the case of different polarizations. Especially, there exists a large focal shift, which is due to the birefringence effect of a uniaxial crystal. In contrast, for conventional isotropic CBCMs, the focal characteristics for different polarizations are similar. Meanwhile, our analysis indicates that the focal performances of CBCMs with small f-number are sensitive to illumination type. It is expected that the CBCMs made of uniaxial crystal should be used as a micropolarization optical filter in micro-optical systems and also offer useful help in application of CBCMs with small f-number.