Wave platesformula

Fresnel Light (pronounced "fre-nel") - a focusable spotlight used in film, television, and theater lighting, which can be adjusted via a knob on the back of the light from "spot" for a narrowly focused beam, to "flood" for a wider beam.  This type of focusable lighting instrument is called a Fresnel because it features a Fresnel Lens, a glass lens with concentric ripples that is visible on the front of the light, casting soft, even illumination across the light's beam.

Wave platesWuthering Waves

The QWP has the interesting property that it transforms L+45P light to RCP light. This is shown in the following Stokes vector calculation:

Source: Digital Lighting & Rendering by Jeremy Birn, definition and 3D images adapted from the book by permission.  This page © 2001 by Jeremy Birn.

where φ is the total phase shift between the orthogonal components of the beam. Two forms of the Mueller matrices that are very important in polarization are the quarter-wave plate (QWP) (φ = π/2) and the half-wave plate (HWP) (φ = π):

Half-wave plate

The Fresnel Lens is named for its inventor, the French physicist Augustin-Jean Fresnel (1788-1827), who designed the Fresnel Lens to efficiently project beams of light from lighthouses.  Fresnel is also known for observing the Fresnel Effect, a phenomenon simulated today by Fresnel Shaders in computer graphics.

Wave plates have the property that along the x-axis (called the fast axis) the x component of the field experiences a phase shift of +φ/2 and, similarly, along the y-axis (called the slow axis) the y component experiences a phase shift of -φ/2. The configuration for the wave plate is seen in the figure.