Pl. lenses; also 8 lens, lens’s, and in Latin form lentes. [a. L. lens lentil, from the similarity in form.]
1. A piece of glass, or other transparent substance, with two curved surfaces, or one plane and one curved surface, serving to cause regular convergence or divergence of the rays of light passing through it.
Now sometimes applied to analogous contrivances for producing similar effects on radiations other than those of light, as in acoustic lens, electric lens.
1693. E. Halley in Phil. Trans., No. 205. 960. Finding the focus of any sort of lens.
1704. Newton, Opticks, I. (1721), 8. A Glass spherically Convex on both sides (usually called a Lens). Ibid., 57. According to the difference of the Lenses, I used various distances.
1719. Desaguliers, in Phil. Trans., XXX. 1017. Telescopes made up of Convex Lentes.
1726. trans. Gregory’s Astron., I. 347. By the help of Speculums or Lens.
1781. Cowper, Charity, 385. He claps his lens, if haply they may see, Close to the part where vision ought to be.
1831. Brewster, Optics, v. § 51. 45. Images are formed by lenses in the very same manner as they are formed by mirrors.
c. 1865. J. Wylde, in Circ. Sci., I. 65/1. The Coddington lens is an equally valuable little microscope.
1881. Routledge, Science, xii. 279. The property of a lens to form an image depends upon its power of refracting the rays of light.
b. spec. A lens or combination of lenses used in photography.
1841. Fox Talbot, in Proc. Roy. Soc., IV. 313. The object lens.
1889. C. D. Warner, in Harper’s Mag., Jan., 258/1. So thoroughly has this region been set forth by the pen and the pencil and the lens that I am relieved of the necessity of describing it.
2. Anat. a. = crystalline lens (see CRYSTALLINE a. 6). b. One of the facets of a compound eye.
a. 1719. Quincy, Lex. Physico-Med. (1722), s.v.
1806. Med. Jrnl., XV. 106. Indistinct vision … can only be remedied by the depression of the lens.
1840. G. Ellis, Anat., 96. It is this ariery … that is to be avoided when the needle is used to depress the lens.
1870. Rolleston, Anim. Life, Introd. 54. Except in Owls and aquatic Birds, the lens is flat.
b. 1868. Duncan, Insect World, Introd. 2. Eyes [of insects] composed of many lenses.
3. attrib. and Comb., as (sense 1, 1 b) lens-shutter, -tube; lens-like, -shaped adjs.; (sense 2) lens-capsule, -matter, -sector; lens-eye = 2 b; lens-form = LENTIFORM.
1874. G. Lawson, Dis. Eye, 128. The *lens-capsule may be so tough that the point of the needle will puncture but not lacerate it.
1839–47. Todd, Cycl. Anat., III. 769/1. The *lens-eyes of insecta.
1787. Fam. Plants, I. 16. Seeds solitary, *lens-form.
1836–9. Todd, Cycl. Anat., II. 960/1. It [i.e., the facet] is convex on its external and internal surface, or *lens-like.
1874. G. Lawson, Dis. Eye, 157. In cases where there is some *lens matter enclosed between the anterior and posterior layers of the capsule.
1879. Rep. St. George’s Hosp., IX. 484. A zone of central opacity in each lens, with the normal *lens-sectors strongly marked therein.
1839. Lindley, Introd. Bot. (ed. 3), 447. *Lens-shaped…; resembling a double convex lens; as the seeds of Amaranthus.
1887. W. Phillips, Brit. Discomycetes, 365. The conical points expand into lens-shaped … discs.
1891. Anthony’s Photogr. Bull., IV. 158. Your *lens shutter, note book and other trifles are bestowed in your pockets. Ibid. (1890), III. 198. The hood is … arranged to slide out and in on the *lens tube.
Hence Lensed a., provided with a lens or lenses. Lensless a., having no lens or lenses.
1859. Sala, Tw. round Clock (1861), 274. If you eye him narrowly through the many-lensed lorgnette.
1892. Illustr. Lond. News, 1 Oct., 431/3. An eye lensed like a microscope, though also lensed like yours and mine.
1899. Cagney, trans. Jaksch’s Clin. Diagn., i. (ed. 4), 80. The lensless spectroscope consists of two tubes.
