(a) (b) (c)

B. Reflection of light from optical surfaces

When light is incident on an interface between two transparent optical media—such as between air and glass or between water and glass—four things can happen to the incident light.

• It can be partly or totally reflected at the interface.
• It can be scattered in random directions at the interface.
• It can be partly transmitted via refraction at the interface and enter the second medium.
• It can be partly absorbed in either medium.

In our introductory study of geometrical optics we shall consider only smooth surfaces that give rise to specular (regular, geometric) reflections (Figure 3-4a) and ignore ragged, uneven surfaces that give rise to diffuse (irregular) reflections (Figure 3-4b).