| 释义 |
Herschel Astron.|ˈhɜːʃəl|
1. A name proposed (and to some extent used) for the planet now called Uranus, after its discoverer, Sir William Herschel in 1781.
1819Pantologia, Herschel, the name by which several astronomers call the primary planet discovered by Dr. Herschell in March 1781. 1878Newcomb Pop. Astron. 355 Herschel proposed to call the new planet Georgium Sidus..Lalande thought the most appropriate name of the planet was that of its discoverer, and therefore proposed to call it Herschel.
2. Used attrib. or in the possessive to designate certain phenomena or principles discovered by or related to the work of Sir William or Sir John Herschel (see Herschelian a.), as Herschel('s) condition, a condition that must be satisfied by a system of lenses if spherical aberration is to be absent in the images of two neighbouring objects; Herschel effect, the partial destruction of the latent image on a photographic negative by the action of infra-red radiation; Herschel's fringes, spectral fringes observed in a prism standing on a plane mirror at the line of separation between the brighter field, due to incident light internally reflected by the prism, and the darker field, due to light externally reflected by the mirror, first observed by Sir William Herschel.
1890T. Preston Theory of Light viii. 153 (heading) Herschel's fringes. 1909Jrnl. Chem. Soc. XCVI. ii. 141 Warnerke's modification of the Herschel Effect and the Preparation of the Substance of the Latent Image. 1910J. P. C. Southall Princ. & Methods Geom. Optics xii. 394 It has..been suggested that the other requirement should be the so-called Herschel-Condition; that is, that the function ϕ1Z1 + ϕ2Z2 should vanish not only for the particular value of x1 but also for object-points on the axis very near to the point M1 to which the value x1 belongs. 1932Hardy & Perrin Princ. Optics vi. 98 The condition that n sin ½θ/n′ sin ½θ′ = a constant must be satisfied for all values of θ. This is commonly called the Herschel condition although it had not been formulated mathematically when Herschel constructed his objective. Ibid. xi. 233 This Herschel effect has a very important significance in connection with theories of the latent image but has not been found very useful as a technique for infrared photography. 1957R. S. Longhurst Geom. & Physical Optics xiv. 280 Herschel's condition is the condition that must be satisfied if the system is to form, simultaneously, a good image of a neighbouring axial object point. |