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
1) To choose or take as one's own; make one's own by selection or assent.
The act of adopting. The state of being adopted.
Of or involving adoption. Acquired or related by adoption.
Fr.: lumière catoptrique
Light that is reflected from a curved surface mirror.
Fr.: système catoprtique
An optical system in which the light is reflected only.
The area of → optics which treats of the laws and properties of light reflected from reflective surfaces.
Fr.: optique cohérente
A branch of optics that uses coherent radiation to produce holographic three-dimensional images of objects.
A unit of optical measurement that expresses the refractive power of a lens or prism. In a lens or lens system, it is the reciprocal of the focal length in meters.
L. dioptra, from Gk. di-, variant of dia- "passing through, thoroughly, completely" + op- (for opsesthai "to see") + -tra noun suffix of means.
Dioptr loanword from Fr.
An instrument used in antiquity to measure the apparent diameter of the Sun and the Moon. It was a rod with a scale, a sighting hole at one end, and a disk that could be moved along the rod to exactly obscure the Sun or Moon. The Sun was observed directly with the naked eye at sunrise or sunset in order to prevent eye damage. Aristarchus (c.310-230 B.C.), Archimedes (c. 290-212 B.C.), Hipparchus (died after 127 B.C.), and Ptolemy (c.100-170 A.D.) used the dioptra. The instrument could also serve for measurement of angles, land levelling, surveying, and construction of aqueducts and tunnels.
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
To make a choice; choose (usually followed by for).
From Fr. opter "to choose," from L. optare "to choose, desire, wish for," from L. optare "to desire, choose," from PIE root *op- "to choose, prefer."
Optidan, from L. optare, as above.
Of, relating to, or constituting a verbal mood that is expressive of wish or desire.
Optâné, optmand, from opt present stem of optidan, → opt, + adj. suffixes -âné, -mand. -yi.
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.