| 单词 | aperture number |
| 释义 | > as lemmasaperture number 4. Optics. The space through which light passes in any optical instrument (though there is no material opening). Also attributive. aperture number, aperture ratio (see quot. 1953). ΘΚΠ the world > physical sensation > sight and vision > optical instruments > [noun] > instrument for looking through > parts of sight-hole1559 aperture1665 diaphragm1665 reticule1728 reticle1731 wire1737 web1746 screena1764 eye cap1822 spider-line1829 cobweb1837 slit1863 1665 Philos. Trans. (Royal Soc.) 1 19 I saw..with one Aperture of my glass more than 40 or 50. 1728 E. Chambers Cycl. (at cited word) The focal Distances of the Eye-Glasses are to be proportional to the Apertures. 1879 J. N. Lockyer Elem. Lessons Astron. (new ed.) vi. 218 The aperture of the object-glass, that is to say, its diameter. 1879 H. Grubb in Proc. Royal Dubl. Soc. 181 That roundness and relief that is admired so much in photographs taken with large aperture lenses. 1889 W. A. Watts in Year-bk. Photogr. 1889 91 The desirability of ascertaining the aperture ratio (f/n) of each stop employed is universally admitted. 1953 S. W. Amos & D. C. Birkinshaw Television Engin. I. 166 The aperture number or aperture ratio, which is defined as the ratio of the focal length of the system to the diameter of the entrance pupil. < as lemmas |
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