Ray diagrams

"A-rre, they're diagrams" - Issac Newton

Some basic terminology

  • Object - The thing that's emitting light (whether reflecting or producing, doesn't make a difference)

  • Image - A visual representation of an object; where light rays bounce of/are produced from the object, and they converge at a point (that's where the image is formed)

  • Center of curvature - If a spherical mirror were part of a sphere, then the center of the sphere would be center of curvature.

Center of Curvature
  • Focus - The point where the parallel light rays converge to form the image. If the aperture (see below) is too big, then the light rays will not converge at a single point, resulting in a distorted image

  • Pole - The Point inline with focus and center of curvature, at the center of the mirror

  • Focal length - The distance between the pole and the focus

Focal length
  • Radius of curvature - The distance between the Pole and center of curvature, equal to the radius of the sphere. This distance is always 2f2f, that is, two times the focal length. This means that the focus lies exactly between the center of curvature and Pole

  • Aperture - This is the diameter of the mirror itself. This defines how big the mirror is, how much light it can gather, and how much of the complete sphere it makes up.

  • Principal Axis - An imaginary line that goes through the Pole, Focus, and Center of Curvature

Principal Axis