A polarimeter is a scientific instrument used to measure the optical rotation of a substance, which is the degree to which its plane-polarized light is rotated by passing through a sample. This property is a characteristic of chiral compounds, which have different optical rotations in different enantiomers. Polarimeters are commonly used in chemistry, pharmacy, and food science to determine the purity and identity of various substances.
The basic components of a polarimeter include a light source, a polarizer to produce plane-polarized light, a sample cell or tube to hold the substance being analyzed, an analyzing polarizer to measure the rotation of the polarized light, and a detector to measure the intensity of the light after it has passed through the sample. Some polarimeters also have temperature control and automatic data collection capabilities.
Polarimeters can be used to measure the optical rotation of various types of substances, including sugars, amino acids, and drugs. They are especially useful for determining the purity and concentration of pharmaceuticals and other high-value chemicals, as even small impurities can significantly affect the optical rotation. Polarimeters are also used in the food industry to measure the sugar content of fruits and vegetables, and in the research and development of new materials with chiral properties.