| 释义 |
Fresnel|freɪˈnɛl|
[The name of A. J. Fresnel (1788–1827), French physicist and engineer.]
1. Used attrib. and in the possessive to designate apparatus, phenomena, and concepts relating to his work in optics, as Fresnel biprism = biprism; Fresnel diffraction, diffraction in which the diffraction pattern is a non-linear function of the variation in phase across the diffracting aperture or object; Fresnel's formulæ, two formulæ giving the proportion of linearly polarized light reflected from a plane surface in terms of the angles of incidence and refraction (see quot. 19571); Fresnel lens, a lens consisting of a number of concentric annular sections, each of different curvature and so designed that a parallel beam relatively free from spherical aberration can be produced; Fresnel's integrals, the integrals ∫x0 cos ½πt2dt and ∫x0 sin ½πt2dt, used in the theory of Fresnel diffraction; Fresnel('s) mirror or mirrors, two plane mirrors set together at an angle of just less than 180 degrees; Fresnel's rhomb, a glass parallelepiped of such a shape that light can be passed through it to undergo two total internal reflections and emerge parallel to its initial direction.
[1830D. Brewster in Phil. Trans. R. Soc. CXX. 73, I am persuaded that the formulæ of Fresnel are accurate expressions of the phenomena under every variation of incidence and refractive power. Ibid. 77 M. Fresnel's general formula has been adapted to this species of rays.] 1835Rep. Brit. Assoc. 1834 333 M. Poisson applied Fresnel's integral to the case of diffraction by an opaque circular disc. Ibid. 370 The parallelopiped thus constructed, and which is known under the name of Fresnel's rhomb, is of essential service in experiments on circular and elliptic polarization. 1848A. Stevenson Acc. Skerryvore Lighthouse ii. 257 The divergence..may be described as the angle which the flame subtends at the principal focus of the lens, the maximum of which, produced at the vertex of Fresnel's great lens.., is about 5° 9′. 1849G. G. Stokes in Camb. & Dublin Math. Jrnl. IV. 9 There are three particular angles of incidence..for which special results are deducible from Fresnel's formulæ. 1854Fresnel's rhomb [see rhomb 2 b]. 1874tr. Lommel's Nature of Light (1875) xv. 207 (caption) Fresnel's mirror. a1884Knight Dict. Mech. Suppl. 356/2 Fresnel lens, a lens consisting of a central portion of spherical section and surrounding rings, so adapted as to direct the rays practically parallel. 1890,1904Fresnel's biprism [see biprism]. 1905R. W. Wood Physical Optics vii. 195 (heading) Fresnel diffraction phenomena. 1937Jenkins & White Fund. Optics viii. 173 Since Fresnel diffraction is the easiest to observe, it was historically the first type to be investigated. 1937G. S. Monk Light x. 129 A much better device for obtaining the interference between two sections of a wave front..is the Fresnel biprism. 1957Encycl. Brit. XIV. 61/1 If i is the angle of incidence and r that of refraction, the fraction [of light] reflected is sin2(i - r)/sin2(i + r) or tan2(i - r)/tan2(i + r), according to the direction of polarization. These expressions are usually called Fresnel's sine and tangent formulae. 1957Oxf. Compan. Theatre (ed. 2) 476/1 The Fresnel lens spotlight or step-lens spotlight seems to have had more development and use in the U.S.A. than in England. 1959Born & Wolf Princ. Optics i. 50 One may also invert the procedure and produce, by means of Fresnel's rhomb, linearly polarized light from elliptically polarized light. 1966McGraw-Hill Encycl. Sci. & Technol. VII. 185 Another way of splitting the light from the source is the Fresnel double mirror.
2. (With lower-case initial letter.) A name occas. used by spectroscopists for a unit of frequency equal to 1012 Hz (1012 cycles per second).
1939W. R. Brode Chem. Spectroscopy viii. 191 The choice of the fresnel as a unit for recording visible and ultraviolet data is very satisfactory in that the units are not unwieldy. 1951Nature 3 Mar. 367/2 Frequencies expressed in sec.-1 involve large powers of ten (∼ 1015), while the fresnel (= 1012sec.-1) has never become popular. 1960Brode & Corning in W. G. Berl Physical Methods in Chem. Anal. (ed. 2) I. 194 The limits of the visible spectrum in frequency are from 750 to 400 fresnel units. |