n
(astronomy, optics) An optical system in telescopes that reduces atmospheric distortion by dynamically measuring and correcting wavefront aberrations in real time, often by using a deformable mirror.
n
Obsolete spelling of alidade [(cartography, astronomy, surveying) A sighting device used for measuring angles.]
n
(cartography, astronomy, surveying) A sighting device used for measuring angles.
n
(physics, astronomy) The collimation of a telescope by means of a plane mirror
n
An instrument for making such tracings, such as a recording brontometer.
n
Short for Cassegrain reflector. [A combination of a primary concave mirror and a secondary convex mirror, often used in optical telescopes and radio antennas, the main characteristic being that the optical path folds back onto itself, relative to the optical system's primary mirror entrance aperture.]
n
(historical) An instrument or apparatus employed in the ancient Greek mysteries to imitate thunder and lightning.
n
An instrument for constructing triangles in marine surveying, etc.
n
A device for measuring time, such as a watch or clock.
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(astronomy) A small telescope attached to a larger one, used to point it in the correct general direction.
n
(obsolete, rare) An instrument for compounding the resultant of two parallel, simple, harmonic waves.
n
(astronomy) An instrument for determining the time of apparent noon. It consists of two mirrors and a plane glass in the form of a prism, so that, by the reflections of the sun's rays from their surfaces, two images are presented to the eye, moving in opposite directions, and coinciding at the instant the sun's centre is on the meridian.
n
An instrument for observing the dip of the horizon.
n
The tube that is drawn out in order to expand a telescope.
n
(surveying) A level having a short telescope, usually an inverting one, rigidly fixed to a table capable only of rotatory movement in a horizontal plane.
n
A mechanical instrument used to trace out an ellipse.
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(astronomy) A small telescope, or other sighting device, mounted on top of a main telescope to enable approximate directional positioning.
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(physics) An optical device that uses diffraction through alternate transparent and opaque rings to function as a lens
n
A Roman surveying instrument having plumb lines hanging from four arms at right angles.
n
A mechanical device that uses a combination of pendulums to generate an image based on Lissajous curves.
n
(astronomy) An apparatus for viewing the Sun without harming the eye, by means of an optical filter that attenuates most of sunlight while allowing only a small amount of the solar radiation.
n
(photography, historical) An early form of viewfinder.
n
a photoelectric device for intensifying faint astronomical images
n
(earth science) A body of rock, ice, or water shaped like a convex lens.
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A tool for finding whether a surface is level, or for creating a horizontal or vertical line of reference.
n
Alternative form of levelling staff [(surveying, archaeology) A graduated pole used in the process of establishing heights and altitudes.]
n
(historical) An instrument for measuring the refractive indices of crystal materials.
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(obsolete) An instrument used by surveyors to find right angles.
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A catadioptric telescope with a meniscus corrector.
n
An optical device for making pressure volume diagrams for high-speed engines, involving a light-tight box or camera having at one end a small convex mirror reflecting a beam of light onto the ground glass or photographic plate at the other end. The mirror is pivoted so that it can be moved so as to copy the motion of the engine piston on a smaller scale.
n
(historical) An ancient instrument for finding two mean proportionals between two given lines, required in solving the problem of the duplication of the cube.
n
(historical) An instrument with a lantern for measuring colours, used in conjunction with a telescope to note the colours of stars.
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A kind of reflecting telescope: a modified Cassegrain telescope with light reflected sideways before reaching the primary mirror again.
n
A type of reflecting telescope using a concave primary mirror and a flat diagonal secondary mirror.
n
An instrument for orientating.
v
To identify something quite precisely using a telescope.
n
A circular or semicircular tool for drawing or measuring angles.
n
Any of several designs of optical (or other) instrument that is used to measure the distance to an object
n
(surveying) A theodolite which follows the movements of a prism and can be used by a one-man crew.
n
A (usually rigid), flat, rectangular measuring or drawing device with graduations in units of measurement; a straightedge with markings.
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(astronomy) A camera mounted in a Schmidt telescope
n
(astronomy) A telescope, having a wide field of view, comprising a thin aspheric lens and a large concave mirror
n
(surveying) A graphometer.
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Any of a series of measurements of atmospheric opacity taken using a telescope that dips from a high to a low elevation
n
A combined spectroscope and polariscope.
n
(crystallography) An optical instrument used in determining the position of the planes of light-vibration in sections of crystals.
n
(obsolete, rare) A picture taken by the agency of the solar rays; a photograph.
n
An assembly for protecting a space telescope from solar heat.
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The science of accurately determining the position of points and the distances between them.
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(Britain) A graphic device used to illustrate swing in an election.
n
Any instrument used in astronomy for observing distant objects (such as a radio telescope).
n
A house with multiple attachments connected serially, decreasing in size.
n
A telescope which, unlike most telescopes used for astronomical purposes, contains an arrangement of lenses presenting an erect (non-inverted) image to the observer, suitable for observation of objects on the Earth's surface.
n
A surveying instrument, consisting of a small mounted telescope, used to measure horizontal and vertical angles.
n
Synonym of transit instrument
n
An instrument for solving plane right-angled figures by inspection.
n
A telescope devised for looking into a body of water.
n
A kind of theodolite shaped like the capital letter Y.
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