SCHOLAR
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| SCHOLAR
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Glossary
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| birefringence |
 | The property of some materials to split an incident beam into two beams polarised at right angles to each other. |
| Brewster's Law |
|
A beam of light travelling in a medium of refractive index n
1 will be 100% polarised by reflection from a medium of refractive index n
2 if the angle of incidence ip
obeys the relationship 
|
| dichroism |
| The property of some materials to absorb light waves oscillating in one plane, but transmit light waves oscillating in the perpendicular plane. |
| liquid crystal displays |
| A display unit in which electronically-controlled liquid crystals are enclosed between crossed polarisers. If no signal is supplied to the unit, it transmits light. When a signal is applied, the liquid crystal molecules take up a different alignment and the cell does not transmit light, hence appearing black. |
| Malus' law |
|
If a polarised beam of light, intensity I
0, is incident on a sheet of Polaroid, with an angle  between the plane of polarisation and the transmission axis, the transmitted beam has intensity I
0cos2
 . |
| optical activity |
| The effect of some materials of rotating the plane of polarisation of a beam of light. |
| photoelasticity |
| The effect of a material becoming birefringent when placed under a mechanical stress. |
| polarisation |
| The alignment of all the oscillations of a transverse wave in one direction. |
| polarised light |
| Light in which all the electric field oscillations are in the same direction. |
| saccharimetry |
| A technique which uses the optical activity of a sugar solution to measure its concentration. |
| transmission axis |
| The transmission axis of a sheet of Polaroid is the direction in which transmitted light is polarised. |
| unpolarised light |
| Light in which the electric field oscillations occur in random directions. |
©Heriot-Watt University 2001