Introduction to Optical Metrology

5.4    PHOTOELASTICITY

Light is a very tiny part of the electromagnetic spectrum. The electromagnetic waves are transverse waves; electric and magnetic field vectors are orthogonal and vibrate perpendicular to the direction of propagation in free space or in an isotropic medium. In fact, electric field vector, magnetic field vector, and propagation vector form an orthogonal triplet. The photo effects, like seeing or the recording on a photographic emulsion, are attributed to the electric field vector and hence while dealing with light, we are only concerned with electric field vector ($\overrightarrow{E}$ vector).

Let us consider a plane wave propagating along the z-direction and the electric vector confined to the y–z plane. The tip of the electric vector describes ...