Optical edge detection with adjustable resolution using the planar liquid crystal Alvarez lens

In this Letter, we propose an optical edge detection method with adjustable resolution using a planar liquid crystal Alvarez lens (LCAL). A planar liquid crystal Alvarez lens was fabricated by laser direct writing. When the focal length of the liquid crystal Alvarez lens changes and linearly polarized light (LP) passes through the liquid crystal Alvarez lens, the angle between the emitted left-handed circularly polarized light and right-handed circularly polarized light can be controlled, enabling adjustable resolution edge detection. The lens can adjust an edge width from 32.5 µm to 73.7 µm without requiring any rotation or axial displacement. Moreover, it can accomplish comprehensive edge detection across a broadband spectral range. This edge detection method could offer a potential application value for compact optical devices such as high-contrast microscopes and smart cameras.