Ray Optics 3: Ray tracing

Lenses are named according to their surfaces and according to their effect on rays of light parallel to the optical axis. Converging lenses bring parallel rays of light together to a common point (focus.) Diverging lenses do the opposite by spreading out parallel rays of light.

A convex lens is converging and a concave lens is diverging. Some lenses only have one curved surface and the other surface is flat. A plano-convex lens is converging and a plano-concave lens is diverging. A concavo-convex lens can be diverging or converging depending on the relative curvatures of the concave and convex sides.

Ray Tracing Terms,
optical axis
focal point, focal length (f)
object plane (P)
image plane (P’)
object distance (s)
image distance (s’)

Image Properties:
real images
virtual images
inverted images
erect images
magnification

Special Rays of Ray Tracing:
1. Ray coming into the lens parallel to the optical axis
2. Ray striking the lens at the optical axis
3. Ray coming to the lens from a focal point
4. (for diverging lenses) Ray coming to the lens as if it was going to go through the focal point on the other side of the lens.