Psychology -> The Way in Which Light is Detected and Focused on the Retina
• Diagram of the eye.
• Pupillary opening
The way in which light is detected and focused on the retina.
Light is the physical energy source for vision. However, the receptor cells in the eye cannot detect the total electromagnetic radiation spectrum. The narrow band which the receptors respond to is called the visible light spectrum, ranging from 300 nanometres (violet) to 740 nanometres (red).
Light waves from the visible light spectrum enter the eye through the cornea which is a thin, protective covering over the eye. The cornea bends the incoming light onto the lens. The iris is the coloured part of the eye which contracts or expands governing the size of the pupil. The light waves travel through the pupil and reach the lens. The lens further bends the light waves on to the back of the eye called the retina. The retina is neural tissue and contains two types of photoreceptors called rods and cones. There are more rod photoreceptors than cone photoreceptors in the human retina.