Irradiance-tailoring integral-illumination polarization homogenizer based on anamorphic aspheric microlens arrays.

Abstract

In the realm of active polarization detection systems, the imperative for polarization illumination systems with high-uniformity and predefined-shape irradiance distribution is evident. This paper introduces a novel anamorphic aspheric (AAS) microlens array (MLA) integral polarization homogenizer, incorporating projection MLA (PMLA), condenser MLA (CMLA), polarization film (PF), and a sub-image array (SIA) mask based on Kohler illumination principles. Firstly, the optimal design of an AAS-based projection sub-lens is proposed to facilitate the creation of a short-working-distance, predefined-geometric and sharp polarization irradiance tailoring. The SIA mask is constituted by plenty of predistortion SIs, which are generated through a combination of chief ray tracing and the radial basis function (RBF) image warping method. In addition, accompanied with tolerance sensitivity analysis, detailed analysis of stray light generation factors and proposed elimination or suppression methods further ensure the engineering reliability and stability of the proposed system. A compact integral-illumination polarization homogenizer design example is realized with an overall irradiance uniformity exceeding 90% and a volume of 25 mm × 25 mm × 18.25 mm. Different predefined-geometrical-profile and high-uniformity polarization irradiance distribution can be achieved by substituting different SIA masks and PFs, without replacing MLA optical elements, which greatly saves cost. Substantial simulations and experiments corroborate the efficacy of our polarization homogenizer.