Fr.: optique active
A technique for improving the → resolving power of a telescope by controlling the shape of the main mirror at a relatively slow rate. The → image quality is optimized automatically through constant adjustments by in-built corrective → actuators operating at fairly low temporal frequency ~0.05 Hz or less. → adaptive optics.
Fr.: optique adaptative
A technique for improving the → image quality of a telescope against → atmospheric turbulence in which image distortions are compensated by high-speed changes in the shape of a small, thin mirror. → wavefront; → wavefront distortion; → wavefront correction; → Strehl ratio; → tip-tilt mirror, → Shack-Hartmann wavefront sensor, → active optics.
ADaptive Optics Near Infrared System (ADONIS)
Fr.: ADaptive Optics Near Infrared System (ADONIS)
An → adaptive optics instrument used on the → European Southern Observatory (ESO) 3.6-m telescope at La Silla. It was an upgraded version of COME-ON-PLUS, the → Very Large Telescope (VLT) adaptive optics prototype. It had 52 → actuators and performed corrections of the mirror 200 times per second. The reference → wavefront was sensed in the → visible. The observation was done in the → near-infrared (1-5 μm).
adaptive optics system
râžmân-e nurik-e niyâveši
Fr.: système d'optique adaptative
Fr.: optique cohérente
A branch of optics that uses coherent radiation to produce holographic three-dimensional images of objects.
extreme adaptive optics
nurik-e niyâveši-ye ostom
Fr.: optique adaptative extrême
An → adaptive optics system with high-contrast imaging and spectroscopic capabilities. Extreme adaptive optics systems enable the detection of faint objects (e.g., → exoplanets) close to bright sources that would otherwise overwhelm them. This is accomplished both by increasing the peak intensity of point-source images and by removing light scattered by the atmosphere and the telescope optics into the → seeing disk.
Fr.: optique géométrique
A branch of physics that deals with reflection and refraction of rays of light without reference to the wave or physical nature of light.
Large Synoptic Survey Telescope (LSST)
teleskop-e bozorg-e hanvini barâye bardid
Fr.: Grand Télescope d'étude synoptique
A new kind of optical telescope with a 6.7-m diameter → primary mirror, currently under construction in Chile. It will have a large → field of view almost 10 square degrees of sky, or 40 times the size of the full moon. The LSST will move quickly between images to rapidly → survey the sky. From its mountain top site in the Andes (Cerro Pachon, a 2,682-m high mountain in Coquimbo Region), the LSST will take more than 800 panoramic images each night with its 3.2 billion-pixel camera, recording the entire visible sky twice each week. Each patch of sky it images will be visited 1000 times during the survey, each of its 30-second observations will be able to detect objects 10 million times fainter than visible with the human eye. The LSST's combination of telescope, mirror, camera, → data processing, and survey will capture changes in billions of faint objects. Hence, the data it provides will be used to create an animated, three-dimensional cosmic map with unprecedented depth and detail. This map will serve many purposes, from locating the → dark matter and characterizing the properties of the → dark energy, to tracking transient objects, to studying our own Milky Way Galaxy in depth. It will even be used to detect and track → potentially hazardous asteroids that might impact the Earth.
off-axis optical system
râžmân-e nurik-e ap-âsé
Fr.: système optique hors axe
1) nuri, nurik; 2) didgâni
1) Of or pertaining to the eye or sight.
From M.Fr. optique, from M.L. opticus "of sight or seeing," from Gk. optikos "of or having to do with sight," from optos "seen, visible," from op-, root of opsesthai "be going to see," related to ops "eye," from PIE *okw- "eye/see."
1) Nuri, nurik, from nur, → light + -i, -ik
adj. suffix → -ic.
Fr.: axe optique
The direction in a doubly refracting crystal in which light is propagated without double refraction.
1) nuri, nurik; 2) didgâni
1) Of, pertaining to, or applying optics or the principles of optics.
Fr.: aberration optique
Fr.: activité optique
The property possessed by some substances and their solutions of rotating the plane of vibration of → polarized light. When a beam of → linearly polarized light is sent through an optically active substance, such as crystalline quartz and sugar solution, the direction of vibration of the emerging linearly polarized light is found to be different from the original direction. Those which rotate the → plane of polarization to the right, for an observer looking in the incoming beam, are called → dextrorotatory or right handed; those which rotate it to the left, → levorotatory or left handed. Optical activity may be due to an asymmetry of molecules of a substance (solutions of cane sugar) or it may be a property of a crystal as a whole (crystalline quartz).
Fr.: analyse optique
The mathematical evaluation of an optical system to determine its basic optical properties and image quality characteristics.
Fr.: autocorrélateur optique
An instrument used to test lenses by utilizing the → optical transfer function. It consists of a HeNe laser, a beamsplitter and two mirrors.
âse-ye nuri (#)
Fr.: axe optique
Line passing through the optical center and the center of curvature a spherical mirror or lens.
miz-e nurik, ~ nuršenâxti
Fr.: banc optique
A track or table on which sources, lenses, mirrors, and other optical components can be mounted and moved. It is used in optics experiments.
→ optical; bench, M.E., from O.E. benc "long seat;" cf. Da. bænk, M.Du. banc, O.H.G. banch.
Miz "table," originally "preparations for entertaining a guest; guest;" Mid.Pers. mêzd "offering, meal;" nurik, nuršenâxti, → optical.
markaz-e nuri (#)
Fr.: centre optique
Of a thin lens, a point situated at the geometrical center of the lens, through which an incident ray passes without being deviated.
Fr.: composante optique