"Artificial eye for scotopic vision with bioinspired all-optical photosensitivity enhancer" by Hewei Liu, Yinggang Huang, and Hongrui Jiang
From the abstract: "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."
The main idea is to condense the light into a smaller area by means of "thousands of microphotocollectors (μ-PCs). The miniaturized, low-cost, and zero-power-consumption device presented here can be implemented independently in imaging systems, or combined with other image enhancement technologies." A 2x-3x improvement in light sensitivity has been reported:
