We have covered enough concepts in this chapter to describe the basic operation of the human eye, which is clearly an important component in any VR system. Here it will be considered as part of an optical system of lenses and images. The physiological and perceptual parts of human vision are deferred until Chapter 5.
Figure 4.24 shows a cross section of the human eye facing left. Parallel light rays are shown entering from the left; compare to Figure 4.11, which showed a similar situation for an engineered convex lens. Although the eye operation is similar to the engineered setting, several important differences arise at this stage. The focal plane is replaced by a spherically curved surface called the retina. The retina contains photoreceptors that convert the light into neural pulses; this is covered in Sections 5.1 and 5.2. The interior of the eyeball is actually liquid, as opposed to air. The refractive indices of materials along the path from the outside air to the retina are shown in Figure 4.25.