| 单词 | point focus |
| 释义 | > as lemmaspoint focus point focus n. Physics a focus of a beam of light, particles, etc., which is small enough to be considered as a point. ΘΚΠ the world > matter > physics > electromagnetic radiation > light > emission of light, radiation > [noun] > meeting point focus1664 visual point1679 focal point1713 chemical focus1841 point focus1908 1908 L. Laurance Gen. & Pract. Optics xii. 329 Thus, rays in the pencil do not have a point focus, since there are two focal lines. 1966 D. G. Brandon Mod. Techniques Metallogr. 135 The incident intensity can be increased by using a point-focus X-ray source with the sample close to the source. 1992 S. P. Maran Astron. & Astrophysics Encycl. 602/1 As only the paraboloid has a point focus, all of the so-called shaped-reflector antennas incorporate elaborate feed antennas. < as lemmas |
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