dark-groundadj.

Brit.

/ˈdɑːkɡraʊnd/, U.S.

/ˈdɑrkˌɡraʊnd/

Origin: Formed within English, by compounding. Etymons: dark adj., ground n.

Etymology: < dark adj. + ground n.

Microscopy.

Designating a technique of optical microscopy in which the objective lens receives only scattered radiation from the sample (which appears as bright against a dark background), and direct radiation is blocked; of or relating to this type of microscopy; esp. in dark-ground illumination. Cf. dark-field adj.

ΚΠ

1856 Q. Jrnl. Microsc. Sci. 4 206 With many microscopes is furnished, for the purpose of a dark-ground illumination, what is called a ‘spotted lens’; by this means the object itself appears beautifully illuminated, while the entire field by which it is surrounded is perfectly dark.

1965 W. J. Garnett Freshwater Microsc. (ed. 2) iii. 55 It is important with all dark-ground work to use a strong source of light.

1990 Proc. Royal Microsc. Soc. 25 322/1 The best effects are given by a high power dark ground condenser with an inner aperture in excess of NA 1.0, necessary for total reflection.

2001 Microbiol. Austral. 22 A45/1 Specialised tests, like dark ground illumination for syphilis, require laboratory skills and equipment that are often unavailable.

This entry has been updated (OED Third Edition, December 2021).

单词	dark-ground
释义	dark-groundadj. Brit. /ˈdɑːkɡraʊnd/, U.S. /ˈdɑrkˌɡraʊnd/ Origin: Formed within English, by compounding. Etymons: dark adj., ground n. Etymology: < dark adj. + ground n. Microscopy. Designating a technique of optical microscopy in which the objective lens receives only scattered radiation from the sample (which appears as bright against a dark background), and direct radiation is blocked; of or relating to this type of microscopy; esp. in dark-ground illumination. Cf. dark-field adj. ΚΠ 1856 Q. Jrnl. Microsc. Sci. 4 206 With many microscopes is furnished, for the purpose of a dark-ground illumination, what is called a ‘spotted lens’; by this means the object itself appears beautifully illuminated, while the entire field by which it is surrounded is perfectly dark. 1965 W. J. Garnett Freshwater Microsc. (ed. 2) iii. 55 It is important with all dark-ground work to use a strong source of light. 1990 Proc. Royal Microsc. Soc. 25 322/1 The best effects are given by a high power dark ground condenser with an inner aperture in excess of NA 1.0, necessary for total reflection. 2001 Microbiol. Austral. 22 A45/1 Specialised tests, like dark ground illumination for syphilis, require laboratory skills and equipment that are often unavailable. This entry has been updated (OED Third Edition, December 2021). < adj.1856
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