Abstract: Microlens array elements are widely used in advanced imaging systems such as infrared detection and photoelectric sensing due to their unique functions such as beam shaping, equalization, diffusion and microfocusing. The mass manufacturing of its components mostly uses injection molding and molding processes to accurately copy the microstructure on the surface of the mold to the surface of the component. Due to the defects such as knife lines on the surface of the mold obtained by ultra-precision and close cutting, the further improvement of the performance of the component is limited, and subsequent polishing treatment is required. In order to solve the technical problem that the current microlens array polishing technology is difficult to take into account the surface shape accuracy and surface quality, a non-contact conformal polishing method based on shear thickening principle for microlens array molds is proposed, a full-diameter polishing tool for spherical molds is designed, the distribution of surface stress and slip velocity of the mold during polishing is analyzed, and the polishing performances of the Ni-P alloy microlens array is studied. The results show that the proposed shear thickening conformal polishing has excellent polishing performances for the microlens array structure. After polishing, the defects such as knife lines on the surface of the microlens array are significantly removed, the high-frequency error is significantly reduced, and the rainbow pattern phenomenon is significantly suppressed. The surface roughness of the mold decreased from the initial 2.01 nm Sa to 1.07 nm Sa, and the shape accuracy before and after polishing changed by less than 25 nm.

Key words: microlens arrays, shear thickening polishing, conformal polishing performances, tool mark remove, shape retention