The light then undergoes TIR at two different faces. The incident light is linearly polarized at a 45° angle to the plane of incidence. The production of circularly polarized light by TIR can be conveniently demonstrated by a glass parallelepiped in which light undergoes TIR at two opposite faces - a setup now known as a Fresnel rhomb.Ī Fresnel rhomb is a type of glass prism that manipulates the polarization of light. By further studying light polarization, he was able to explain that the total internal reflection (TIR) of light does not depolarize incident linearly polarized light, as previously thought, but rather changes it to elliptically or circularly polarized light. The direction of propagation is in blue, and the total electric field amplitude is in yellow.įresnel’s discovery of linearly and circularly polarized radiation lent support to his hypothesis that light is a pure transverse wave (with no longitudinal component), meaning that the oscillations of the electric and magnetic fields are always perpendicular to the direction of propagation. The x – and y -components are shown in red and green, respectively. The net effect is that the sum of these two components has a spiral-like shape, hence the name “circular polarization”.Ī circularly polarized plane electromagnetic wave. Thus, when one component reaches a maximum or minimum value, the other is zero. Here, the x– and y-components of the electric field are equal in magnitude but are offset by a 90° phase delay. The following plot shows a linearly polarized wave the electric field of the wave itself is shown in yellow, whereas the x– and y-components are shown in red and green, respectively.Ī linearly polarized plane electromagnetic wave.Ĭompare this linearly polarized wave to the circularly polarized wave shown below. We can think of these components as sine or cosine functions that reach their maximum at the same position and also reach zero at the same position. In a linearly polarized plane electromagnetic wave, the two transverse components of the electric field are in phase with each other. In the early 1800s, Augustin-Jean Fresnel, known for his research and inventions in the field of optics, was the first scientist to describe light as linearly, circularly, or elliptically polarized.
Manipulating Linearly and Circularly Polarized Light With the COMSOL Multiphysics® software, engineers can model the effect of a Fresnel rhomb and similar elements on light polarization in optical systems.
A useful way to learn about light polarization, and how to manipulate it, is through a Fresnel rhomb.
Careful manipulation of light polarization can greatly improve image quality by filtering out light from unwanted sources - for example, to minimize glare.
The elongation of an ellipse is measured by its eccentricity e intersects an ellipse at 0, 1, or 2 points, respectively called an exterior line, tangent and secant.When analyzing optical designs, it is essential to consider not only light intensity but also polarization. As such, it generalizes a circle, which is the special type of ellipse in which the two focal points are the same. In mathematics, an ellipse is a plane curve surrounding two focal points, such that for all points on the curve, the sum of the two distances to the focal points is a constant. Ellipses: examples with increasing eccentricity