4. Light sensors

4.1 The eye

The eye, and more specifically the human eye, is a natural imaging system. It consists of an optical part, the cornea and lens, and a photosensitive part, the retina. The latter lines the back of the eye, and has two types of photoreceptor: cones, responsible for daytime vision, and rods, responsible for night vision. These light-sensitive cells capture the light passing through the vitreous body, releasing neurotransmitters which are in turn converted into electrical signals by the underlying...