American researchers have created an artificial eye that can see in the dark by taking cues from nature.
Hongrui Jiang, Professor of Electrical and Computer and Biomedical Engineering at the University of Wisconsin–Madison, said his lens is inspired the Elephant-nosed Fish of west and central Africa, whose retinas are composed of thousands of tiny crystal cups instead of the smooth surfaces common to most animals. These miniature vessels collect and intensify red light, which helps the fish discern its predators.
“We were thinking: ‘Why don’t we apply this idea? Can we enhance the intensity to concentrate the light?’” said Jiang.
The team emulated the fish’s crystal cups by engineering thousands of miniscule parabolic mirrors, each as tall as a grain of pollen. They then shaped arrays of the light-collecting structures across the surface of a uniform hemispherical dome. This arrangement, inspired by the superposition compound eyes of lobsters, concentrates incoming light to individual spots, further increasing intensity.
“We showed fourfold improvement in sensitivity,” he said. “That makes the difference between a totally dark image you can’t see and an actually meaningful image.”
Jiang said most attempts to improve night vision tweak the “retinas” of artificial eyes — such as changing the materials or electronics of a digital camera’s sensor — so they respond more strongly to incoming packets of light.
However, rather than interfering with efforts to boost sensitivity at the back end, Jiang’s group set out to increase intensity of incoming light through the front end, the optics that focus the light on the sensor.
Potential applications include not just photography but bomb-diffusing robots, laparoscopic surgeons and planet-seeking telescopes, all of which need to resolve fine details through almost utter darkness
"These days, we rely more and more on visual information. Any technology that can improve or enhance image-taking has great potential,” he said.
Professor Hongrui Jiang. Photo: Stephanie Precourt