Design and performance estimation of an efficient collector lens using a fisheye metalens

One of the components in a microscope's Köhler illumination system is the collector lens. A collector lens is required to efficiently collect light from the source while producing highly uniform illumination. However, conventional collector lens systems require multiple optical elements, which tends to result in bulky configurations. We analyzed a collector lens design using a fisheye metalens through mathematical modeling and ray-tracing simulations. The single-wavelength design achieves 94.9% uniformity and maintains 93.8% uniformity for an LED source with a 20 nm bandwidth. This compact design demonstrates potential for practical microscopy applications while maintaining high illumination performance.