| 释义 |
varifocal, a.|vɛərɪˈfəʊkəl|
[f. vari- + focal a.]
a. Having a focal length that can be varied.
1945Jrnl. Soc. Motion Picture Engineers XLV. 466 A new positive Vari-Focal view-finder for motion picture cameras. 1962Jrnl. Optical Soc. Amer. LII. 353/2 The two-lens varifocal system consists of a single movable component placed behind a fixed component. 1967Appl. Optics VI. 1085 (heading) Stereoscopic display using rapid varifocal mirror oscillations. 1979Ibid. XVIII. 5/1 We have used a varifocal lens to compensate for changes in refractive index of lens elements with wavelengths from 190 nm to 600 nm.
b. Ophthalm. = omnifocal adj. s.v. omni-. Also ellipt.
1975L. S. Sasieni Princ. & Pract. Optical Dispensing & Fitting (ed. 3) xii. 373 Varifocal lenses have two areas of specified powers, for distance and reading, and an intemediate region in which the power gradually changes, from one to the other. 1982Ophthalmic & Physiol. Optics II. 75 (heading) Theoretical aspects of concentric varifocal lenses. Ibid., Substantial amounts of unwanted astigmatism in the transition zone are intrinsic to the design and to other forms of concentric varifocal. |