Artificial eye for scotopic vision with bioinspired all-optical photosensitivity enhancer

Significance Although biological eyes ingeniously adopt diverse optical approaches to improve their scotopic vision, enhancement of the photosensitivity in artificial imaging systems still clings to electronic methods. Here we present an all-optical strategy to significantly improve the low-light imaging capability of manmade sensors, which is inspired by the optical concept of superposition eyes and elephantnose fish eye. Besides showing an artificial eye whose scotopic vision is largely improved by a bioinspired photosensitivity enhancer, we also demonstrate a complete solution to acquire high-resolution images under low-light conditions with our device. More importantly, our purely optical approach can be used on top of other electronic technologies, which can boost the most state-of-the-art imaging sensor whose photosensitivity is gaining on the physical limitations. The ability to acquire images under low-light conditions is critical for many applications. However, to date, strategies toward improving low-light imaging primarily focus on developing electronic image sensors. Inspired by natural scotopic visual systems, we adopt an all-optical method to significantly improve the overall photosensitivity of imaging systems. Such optical approach is independent of, and can effectively circumvent the physical and material limitations of, the electronics imagers used. We demonstrate an artificial eye inspired by superposition compound eyes and the retinal structure of elephantnose fish. The bioinspired photosensitivity enhancer (BPE) that we have developed enhances the image intensity without consuming power, which is achieved by three-dimensional, omnidirectionally aligned microphotocollectors with parabolic reflective sidewalls. Our work opens up a previously unidentified direction toward achieving high photosensitivity in imaging systems.