Researchers find retinal rods able to detect photon number distribution
(Phys.org)—The eye, whether in humans or other animals, is truly one of nature's most sophisticated advancements, able to convert light into signals the brain can interpret as imagery, all in real time. Most of the actual work is done at the back of the eye where rods and cones, two types of photoreceptors are located. Cones are primarily responsible for the eye's sensitivity to color, while rods, which are far more numerous (some 120 million exit in one human eye), are more sensitive to light in general. To find out just how sensitive rods are, researchers in Singapore have been studying single rod photoreceptors taken from an African Clawed Frog, and have found, as they describe in their paper published in Physical Review Letters, that such rods are able to discern and count single photons and are also able to determine the coherence of very weak pulses of light.