Classical Optics

Optics is study of light and its behaviour. Classical optics is collection of those facts of optics, which were in existence before wave model of light was adopted in 19th century. According to classical optics, light was considered having particle nature. Thus, all the properties which were typical to particles was considered to be of light; like straight line travel, rebounding from the objects it hits, and always travelling through that path which offered minimum resistance.

This theory was widely accepted in 19th century, also called Newtonian era as Newton was alive in that period. However, most of the phenomenon was explained through particle nature, but there were some, which could not be explained without taking into account, wave nature of light. Due to this reason wave, nature of light was also accepted. Now light is considered to have both dual: particle as well as wave nature.

Classical optics divides the study of light into two categories: Ray optics and physical optics. Ray optics describes the propagation of light through rays whereas physical optics employs paraxial approximation to describe the propagation of light. The rules for propagation of light in optical system are based on ray optics.

Classical optics has profound application in many fields including medical imagining. Many medical image techniques rely on the principles of classical optics for the detection as they take into consideration particle nature of light. The most common application of classical optics is use of microscopes as in this ray nature of light is taken into consideration for detection of specific objects.