Instruments

Polarimeter

Citation Formats

General Reference

Science Atlas. "Polarimeter." Accessed August 30, 2026. https://science.interactiveatlas.org/instruments/polarimeter.

APA Style

Science Atlas. (n.d.). Polarimeter. Retrieved August 30, 2026, from https://science.interactiveatlas.org/instruments/polarimeter

BibTeX

@misc{scienceatlas-polarimeter,
  author = {Science Atlas},
  title = {Polarimeter},
  year = {2026},
  url = {https://science.interactiveatlas.org/instruments/polarimeter},
  note = {Accessed August 30, 2026}
}

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 Year

1830 1

Wikipedia 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.

Measures

Optical rotation, the angle through which polarized light is rotated by a chiral sample. 1

Operating Principle

Passes 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

Resolution

Modern polarimeters typically reach a measurement uncertainty of about 0.001 degrees (k=2). 1

Open Questions

Operating Range

Not 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.

Cross-Tradition Connections