Figure 2-31. Paths of rays of light through convergent lens.

TM 9-258

(3) The laws of refraction may be applied to

point where the ray enters. As the refracted ray leaves

plot the path of any ray through any lens. A ray entering

the lens as the emergent ray, it is bent away from its

a lens will bend toward the normal of the lens at that

normal. The normal of any emergent ray is an imaginary

point (fig 2-32). The normal of an incident ray at any

line at right angles to the surface of the lens at the point

point on a lens is an imaginary line at right angles to the

where the ray emerges from the lens.

surface of the lens at the

Figure 2-32. Law of refraction applied to lens.

2-22