Dioptrics

Overview
Dioptrics is the study of the refraction of light, especially by lenses. Telescopes that create their image with an objective that is a convex lens (refractors) are said to be "dioptric" telescopes.

An early study of dioptrics was conducted by Ptolemy in relationship to the human eye as well as refraction in media such as water. Understanding of the principles of dioptrics was further expanded by Alhazen, considered as the father of modern optics.