| 释义 |
afocal, a. Optics.|eɪˈfəʊkəl|
[f. a- 14 + focal a.]
Designating a lens or lens system with a focal power of zero, so that rays entering parallel emerge parallel; neither converging nor diverging.
1932Emsley & Swaine Ophthalmic Lenses (ed. 2) xvii. 294 The two surfaces of this central portion of the glass are practically concentric..so that the glass itself is afocal (no power). 1950K. N. Ogle Binocular Vision xi. 122 The afocal type lens is a little Galilean telescope in that it consists of positive and negative surfaces, analogous to the objective and eye lenses. 1969Focal Encycl. Photogr. (rev. desk ed.) 1488/1 Afocal attachments of variable magnification also exist and produce an effect similar to that of a zoom lens. 1973Physics Bull. July 440/3 Afocal systems such as telescopes, binoculars and periscopic sights. |
