| 释义 |
Collins Concise English Dictionary © HarperCollins Publishers:: dioptre, US diopter /daɪˈɒptə/ n - a unit for measuring the refractive power of a lens: the reciprocal of the focal length of the lens expressed in metres
Etymology: 16th Century: from Latin dioptra optical instrument, from Greek, from dia- through + opsesthai to seediˈoptral adj di•op•ter (dī op′tər),USA pronunciation n. - Opticsa unit of measure of the refractive power of a lens, having the dimension of the reciprocal of length and a unit equal to the reciprocal of one meter. Abbr.: D
- Antiquityan instrument, invented by Hipparchus, to measure the apparent diameter of the sun or moon or to estimate the size or elevation of distant objects.
Also,[esp. Brit.,] di•op′tre. - Greek: instrument for measuring height or levels, equivalent. to di- di-3 + op- (for ópsesthai to see) + -tra noun, nominal suffix of means
- Latin dioptra
- 1585–95
|