For thousands of years, people have been intrigued by the behavior and properties of light. While the philosophers of those eras were able to propose theories about the nature of light, the scientific study of light began in the seventeenth century with the work of Galileo, Snell, Fermat and Newton. Their theories of geometrical optics, as well as the instruments they devised, form the foundation of classical optics.
Light is a form of electromagnetic radiation that propagates as a transverse wave.
As a result, rays, rather than wavefronts, are used to model the propagation of the light. A ray is an idealized pencil of light that travels a straight line within a homogeneous medium. Analyzing the performance of an optical system is a matter of methodically tracing representative rays. This technical manual is a basic introduction to geometrical optics analysis. For more detailed information about specific optical components, systems and coatings, please refer to the introduction to each section of this website.