Optical path difference

{
  "id": "MLC-T-CHM-008275",
  "term": "Optical path difference",
  "field": "Chemistry",
  "definition": "The difference in optical path length between two electromagnetic radiation waves that have traveled through different media or along different geometric paths. It is calculated by subtracting the product of the refractive index and geometric path length for one wave from that of the other. This difference determines the phase relationship between the waves and is measured in units of length, such as meters.",
  "synonyms": [
    "optical retardation"
  ],
  "subject": "Analytical Chemistry",
  "see_also": [
    "path-length",
    "electromagnetic radiation"
  ],
  "references": [
    "PAC, 2021, 93, 647. 'Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)' on page 758 (https://doi.org/10.1515/pac-2019-0203)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/optical-path-difference/"
}