Lens n. (pl. lenses) (Opt.) A piece of glass, or other transparent substance, ground with two opposite regular surfaces, either both curved, or one curved and the other plane, and commonly used, either singly or combined, in optical instruments, for changing the direction of rays of light, and thus magnifying objects, or otherwise modifying vision. In practice, the curved surfaces are usually spherical, though rarely cylindrical, or of some other figure. Lenses Note: Of spherical lenses, there are six varieties, as shown in section in the figures herewith given: viz., a plano-concave; b double-concave; c plano-convex; d double-convex; e converging concavo-convex, or converging meniscus; f diverging concavo-convex, or diverging meniscus.
Crossed lens (Opt.), a double-convex lens with one radius equal to six times the other.
Fresnel lens (Opt.), a compound lens formed by placing around a central convex lens rings of glass so curved as to have the same focus; used, especially in lighthouses, for concentrating light in a particular direction; so called from the inventor.
Multiplying lens or Multiplying glass (Opt.), a lens one side of which is plane and the other convex, but made up of a number of plane faces inclined to one another, each of which presents a separate image of the object viewed through it, so that the object is, as it were, multiplied.
... the doctor swiveled out another eyepiece for his own use and turned a knob on the side of the machine. From the lens next to his arm an almost invisible needle slid out and entered his flesh. Bolden could see it come into the field of view. It didn't hurt. Slowly it approached the dark branching filament, never ... — Bolden's Pets • F. L. Wallace Read full book for free!
... curious scene in our salon the day after the news had come of the great victory of Lens. Clement Darpent had been brought in by my brother, who wished him to hear some English songs which my sister and I had been practicing. He had been trying to learn English, and perhaps understood it better than he could speak ... — Stray Pearls • Charlotte M. Yonge Read full book for free!
... poser. I had certainly seen through those spectacles as clearly as if they had been plain window-glass; and they had certainly given an inverted reflection of the candle-flame like that thrown from the surface of a concave lens. Now they obviously could not be both flat and concave; but yet they had the properties peculiar to both flatness and concavity. And there was a further difficulty. If I could see objects unaltered ... — The Mystery of 31 New Inn • R. Austin Freeman Read full book for free!
... was better done at Lens,' said my fellow-traveller. 'Do you know Lens? They are all miners there, you know—very curious people. I suppose they were glad to come up from under the ground and look at us. Some of the women, too, were pretty—really very pretty. It was all very well arranged. There is a good ... — France and the Republic - A Record of Things Seen and Learned in the French Provinces - During the 'Centennial' Year 1889 • William Henry Hurlbert Read full book for free!
... gaze, And see as in the camera's gloom, The island with its belt of bays, Its chieftained heights all capped with broom, Which as the living lens it fills, Now seems a giant charmed to sleep— Now a broad shield embossed with hills Upon the ... — Poems • Denis Florence MacCarthy Read full book for free!
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