n
A technique using digital signal processing and two loudspeakers directly in front of the listener in order to improve reproduction of stereophonic and surround sound.
n
A type of binary telescope or long-distance binoculars, typically used for amateur astronomy or artillery sighting.
n
An instrument that uses a shaped prism or mirrors to cause an apparent image of external objects to appear as if projected upon a plane surface, so that the outlines may be conveniently traced.
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(obsolete) A reflecting optical glass or instrument; a mirror.
n
An instrument for exhibiting certain chromatic effects of light by means of rapidly rotating disks of various colours.
n
A magnifying glass used to count the density of threads in a textile
n
A simplified focusing mechanism for amateur telescopes, having a smooth spring-loaded shaft which holds the focus tube against four opposing bearing surfaces, and controls its movement.
n
An achromatic telescope in which the coloured dispersion produced by a single object lens of crown glass is corrected by a smaller concave lens, or combination of lenses, of high dispersive power, placed at a distance in the narrower part of the converging cone of rays, usually near the middle of the tube.
n
The dioptre adjustment mechanism of a pair of binoculars or of a camera viewfinder.
n
A form of kaleidoscope having counter-rotating perforated disks
n
Alternative form of fisheye lens [(photography) A wide-angle lens having an extremely wide field of view (approaching or exceeding 180 degrees) and producing images that are circular or distorted by curvature at the edges.]
n
A glass tube for selecting a microscopic object in a fluid.
n
(photography, historical) A device that assists in focusing an object in or before a camera; usually a lens of small magnifying power.
n
A device which allows one to adjust the focus of an instrument such as a telescope.
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A small mirror with a handle.
n
That part of an optical system where real or virtual images are formed
n
A device for projecting the colorful patterns produced by a kaleidoscope.
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A device invented by Thomas Rose that produces the optical illusion of transforming images by means of two concentric wheels moving in opposite directions.
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A type of converging lens that can efficiently focus X-ray radiation.
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(photography) A camera lens that is bundled with a camera body, usually at a discount price.
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Synonym of flicker wheel (“kind of stage lighting”)
n
The apparent enlargement of an object in an image.
n
(optics) A doublet lens (typically composed of a solid lens and a liquid-filled lens) made by microfabrication
n
A reticle used on high-accuracy rifles as a range finder
n
A portable stand with one leg, used to support a camera or telescope.
n
(historical) A device for displaying noctovision.
n
(optics) A disk of high-quality quartz glass having at least one side ground and polished with a deviation in flatness less than 50 nanometers all over, and a surface quality of 5 microfinish or less; used, in an interferometer, to measure the flatness of other surfaces.
n
An instrument, used both for recreational and scientific purposes, which provides a magnified view of distant objects by collecting and focusing light by means of mirrors and/or optical lenses.
n
A form of viewing device that allows the viewer to see things at a different height level and usually with minimal visibility.
n
(historical) An instrument for viewing an enlarged image of engraved prints or maps http://www.monticello.org/site/research-and-collections/perspective-glass.
n
(obsolete) An arrangement of hinged mirrors for the production of multiple images of an object.
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(dated) A glass through which objects appear multiplied, but diminished in size.
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A lens that has multiple facets and forms multiple images
n
(historical) A kind of projector or magic lantern that did not require slides.
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a microscope whose objective is composed of two mirrors, one convex and the other concave; it is free of chromatic aberration
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A telescope which produces a magnified image by reflecting light through a series of mirrors housed in a tube, using a large curved mirror to gather the light and one or more additional mirrors to transmit the light to an eyepiece.
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A telescope which produces a magnified image by refracting light through a series of lenses housed in a tube, with a light-gathering objective lens at one end and an eyepiece at the other.
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An instrument for forest inventory, consisting of a sight hole and marked scales, primarily used to find the height, basal area and diameter of a tree anywhere along the bole.
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A telescopic sight for a rifle.
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(military) A night vision device used to assist snipers in locating their targets in the dark.
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(historical) An apparatus for projecting upon a screen, by means of sunlight, an enlarged view of any object; essentially the same as the combination of lenses used in the magic lantern, taken in conjunction with a heliostat.
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(microscopy) A condensing lens in which the light is confined to an annular pencil by means of a small, round diaphragm (the "spot"), and used in darkfield illumination.
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A compact high-power monocular telescope optimized for detailed observation of distant objects such as wildlife or the strike of a bullet on a target.
n
A small portable telescope.
n
A monocular optical instrument that magnifies distant objects, especially in astronomy.
adj
Capable of seeing distant objects; far-seeing.
n
A device used e.g. on a rifle in aiming a projectile, through which the person aiming looks at the intended target.
n
A toy made of a card with an image on each side; when twirled, the images combine.
n
A simple lens formed by placing a few drops of water in a small brass cell with blackened sides and a glass bottom.
n
A telescope in which the medium between the objective and the eyepiece is water instead of air, used in some experiments involving aberration.
adj
(microscopy) In which a whole two-dimensional image is acquired simultaneously using a wide-area detector array.
n
Alternative form of zoetrope [An optical toy, in which figures made to revolve on the inside of a cylinder, and viewed through slits in its circumference, appear like a single figure passing through a series of natural motions as if animated or mechanically moved.]
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