"optical depth" meaning in English

{
  "forms": [
    {
      "form": "optical depths",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "~"
      },
      "expansion": "optical depth (countable and uncountable, plural optical depths)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Physics",
          "orig": "en:Physics",
          "parents": [
            "Sciences",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "ref": "2006 August, Alexander V. Krivov, Artem G. Feofilov, Valeri V. Dikarev, “Search for the putative dust belts of Mars: The late 2007 opportunity”, in Planetary and Space Science, volume 54, numbers 9–10, →DOI, page 871:",
          "text": "The previous attempt of direct observational detection, undertaken with the Hubble Space Telescope (HST) during the Mars equatorial plane crossing in May 2001, set an upper limit on the normal optical depth to #x5C;sim 3#x5C;times 10#x7B;-8#x7D; for the Phobos ring and #x5C;sim 10#x7B;-7#x7D; for the Deimos torus.",
          "type": "quote"
        }
      ],
      "glosses": [
        "The natural logarithm of the ratio of amount of radiation that hits an object to the amount of radiation that emerges from that object on the other side."
      ],
      "id": "en-optical_depth-en-noun-rkBgXkOu",
      "links": [
        [
          "physics",
          "physics"
        ],
        [
          "natural logarithm",
          "natural logarithm"
        ],
        [
          "ratio",
          "ratio"
        ]
      ],
      "raw_glosses": [
        "(physics) The natural logarithm of the ratio of amount of radiation that hits an object to the amount of radiation that emerges from that object on the other side."
      ],
      "synonyms": [
        {
          "word": "optical thickness"
        }
      ],
      "tags": [
        "countable",
        "uncountable"
      ],
      "topics": [
        "natural-sciences",
        "physical-sciences",
        "physics"
      ]
    }
  ],
  "word": "optical depth"
}

{
  "forms": [
    {
      "form": "optical depths",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "~"
      },
      "expansion": "optical depth (countable and uncountable, plural optical depths)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms with quotations",
        "English uncountable nouns",
        "Pages with 1 entry",
        "Pages with entries",
        "en:Physics"
      ],
      "examples": [
        {
          "ref": "2006 August, Alexander V. Krivov, Artem G. Feofilov, Valeri V. Dikarev, “Search for the putative dust belts of Mars: The late 2007 opportunity”, in Planetary and Space Science, volume 54, numbers 9–10, →DOI, page 871:",
          "text": "The previous attempt of direct observational detection, undertaken with the Hubble Space Telescope (HST) during the Mars equatorial plane crossing in May 2001, set an upper limit on the normal optical depth to #x5C;sim 3#x5C;times 10#x7B;-8#x7D; for the Phobos ring and #x5C;sim 10#x7B;-7#x7D; for the Deimos torus.",
          "type": "quote"
        }
      ],
      "glosses": [
        "The natural logarithm of the ratio of amount of radiation that hits an object to the amount of radiation that emerges from that object on the other side."
      ],
      "links": [
        [
          "physics",
          "physics"
        ],
        [
          "natural logarithm",
          "natural logarithm"
        ],
        [
          "ratio",
          "ratio"
        ]
      ],
      "raw_glosses": [
        "(physics) The natural logarithm of the ratio of amount of radiation that hits an object to the amount of radiation that emerges from that object on the other side."
      ],
      "synonyms": [
        {
          "word": "optical thickness"
        }
      ],
      "tags": [
        "countable",
        "uncountable"
      ],
      "topics": [
        "natural-sciences",
        "physical-sciences",
        "physics"
      ]
    }
  ],
  "word": "optical depth"
}