optical path difference

units: m, cm
synonym: optical retardation
initialism: OPD
https://doi.org/10.1351/goldbook.08653
Path-length difference between the arms of a two-beam interferometer.
Notes:
  1. The term optical retardation is derived from 'phase retardation', which refers to the change in the phase of the electromagnetic radiation in the interferometer.
  2. SI unit: m. Common unit: cm.
Source:
PAC, 2021, 93, 647. (Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)) on page 758 [Terms] [Paper]
Citation: 'optical path difference' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.08653 RIS BibTex EndNote
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