A polarimeter is a scientific instrument used to measure optical rotation, the angle by which linearly polarized light is rotated when passed through an optically active substance.
Facts
Invented YearWikipedia dates the earliest polarimeters to the 1830s without naming a specific inventor or exact year; polarization by reflection, the underlying principle, was found by Etienne-Louis Malus in 1808. MeasuresOptical rotation, the angle through which polarized light is rotated by a chiral sample. 1 Operating PrinciplePasses monochromatic light through a polarizing plate to produce a polarized beam, directs it through the sample, and rotates a second polarizing plate (the analyzer) until it finds the angle of extinction, revealing the sample's optical rotation. 1 ResolutionModern polarimeters typically reach a measurement uncertainty of about 0.001 degrees (k=2). 1 Open Questions
Operating RangeNot stated as a numeric figure in the cited source. 1 The cited source states that fast automatic digital polarimeters give an accurate result regardless of the sample's rotation angle, but names no explicit minimum or maximum rotation-angle range. Classification
Instrument ClassMeasurement or Metrology Instrument 1 Connections
Used In
Chemistry, Disciplines Polarimeters measure the concentration and purity of optically active chemical compounds.
Source Polarimeter (Wikipedia)
Sources
1. Polarimeter (Wikipedia)
WikipediaLead section
A polarimeter is a scientific instrument used to measure optical rotation: the angle of rotation caused by passing linearly polarized light through an optically active substance.
Overview section
Polarimeters measure this by passing monochromatic light through the first of two polarising plates, creating a polarized beam.
Fully automatic section
Fast automatic digital polarimeters yield an accurate result within a few seconds, regardless of the rotation angle of the sample.
Calibration section
The measurement uncertainty of the polarimeter amounts to 0.001° (k=2).
Lede, instrument class
A polarimeter is a scientific instrument used to measure optical rotation, the angle by which linearly polarized light is rotated when passed through an optically active substance.
Used In: Chemistry, Applications section
The ratio, the purity, and the concentration of two enantiomers can be measured via polarimetry.
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