A polarimeter is an optical instrument used to measure the angle that plane-polarized light passes through a given sample.
Parts
The typical polarimeter consists of a viewer, a sample holder, a polarizer (glass, crystal or other polarizing device), an analyzer and a light source.
How It Works
Light passes through the polarizer, causing light to polarize along a plane. This polarized light passes through the test sample, and an analyzer or sensor determines the amount of change in the polarized light's orientation.
Use
The angle at which light passes through a pure substance is specific. Polarimeters calculate the purities of substances and are used in industries such as pharmaceuticals or food science, where the exact concentration of a substance must be known.
Manufacturers
Today, several companies, such as Rudolph, Anton Paar and Jaasco manufacture digital polarimeters for laboratory use. Modern polarimeters also often include wavelength and temperature controls.
Fun Fact
Polarization by reflection was discovered in 1808 by Etienne Malus, and the first polarimeter was invented by French optician Leon Laurent in 1882.
Tags: passes through, light passes, light passes through, polarized light