ABSTRACT
Metrology is the science and technology of making measurements and drawing significant conclusions from a set of data. Optical metrology uses light-based techniques for measurement. Optical metrology mostly utilizes wave nature of light. At the same time, while dealing with many topics involving measurements, some concepts borrowed from other descriptions of light are frequently used. It is known that the direction of light beam propagation can be changed by reflection as well as by refraction. Both of these phenomena have been studied in great detail, and laws of reflection and refraction have been formulated based on the observations. The law of reflection can be stated in two parts. It includes the angle of reflection is equal to the angle of incidence and the incident ray, the normal to the reflecting surface at the point of incidence, and the reflected ray lie in a plane.
