Light is an electro-magnetic wave, produced by vibrating electrical charges. It consists of coupled electric and magnetic fields that oscillate on a plane perpendicular to the direction of propagation. In general, the electric field can be thought as oscillating along two orthogonal directions on this plane, known as polarization. Light is defined as "linearly polarized", if its oscillation is restricted to only one of these orthogonal directions.

Polarized light has several important applications. One example is polarized sunglasses, which suppress light oscillating along the horizontal axis. Light reflected from a surface, like for example the sea or a road, can be intense, resulting in an uncomfortable glare. Since reflection from a surface is particularly strong for horizontally-polarized light, sunglasses that block the horizontal polarization and let the vertical polarization through can be quite effective for clearer, safer vision and more comfortable eyes. A similar principle is used when taking photographs with polarization filters: by adjusting the filter direction, we can suppress scattered light, darkening the sky and therefore increasing the contrast.

David Brewster was a Scottish physicist, who did many important contributions to our understanding of light and light polarization in particular. A pioneer in photography, Brewster invented several optical tools, including an improved stereoscope (a sort of portable 3D-viewing device), the binocular camera and the kaleidoscope. In recognition for his outstanding work, the physics building at Heriot-Watt is dedicated to David Brewster.

Want to learn more?

The study of optical polarization, and light in general, form a core part of all physics degree programmes at Heriot-Watt (2nd year course B28PO Photonics and Optics, 3rd year course B29EM Electromagnetism and 4th year course B20ES Electromagnetism and Laser Physics). Additionally, during summer internships and final year projects there are many opportunities to get to grips with cutting edge research exploiting electromagnetic waves (especially in the form of laser radiation) than span many different regions of the spectrum, from microwaves through visible light and on to X-rays.