steradian


Also found in: Thesaurus, Medical, Financial, Acronyms, Encyclopedia, Wikipedia.
Related to steradian: candela
click for a larger image
steradian
If A = r2 then solid angle Ω = 1 sr.

ste·ra·di·an

 (stĭ-rā′dē-ən)
n. Abbr. sr
A unit of measure equal to the solid angle subtended at the center of a sphere by an area on the surface of the sphere that is equal to the radius squared. The total solid angle of a sphere is 4π steradians.

steradian

(stəˈreɪdɪən)
n
(Units) an SI unit of solid angle; the angle that, having its vertex in the centre of a sphere, cuts off an area of the surface of the sphere equal to the square of the length of the radius. Symbol: sr
[C19: from stereo- + radian]
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.steradian - the unit of solid angle adopted under the Systeme International d'Unites
angular unit - a unit of measurement for angles
sphere - a three-dimensional closed surface such that every point on the surface is equidistant from the center
Translations
stéradian
References in periodicals archive ?
Defense Meteorological Satellite Program's (DMSP's) Operational Linescan System (OLS) light at night data in nanowatts per centimeter squared per steradian (B).
The optical output of this highly efficient emitter is 720 milliwatts (mW) at a current of 1 amp, with a radiant intensity of 1,000 milliwatts per steradian (mW/sr).
A] to constant measure h, then define kg Hyperfine 9,192,631,770/s second splitting of cesium Luminous 683 candela steradian candela efficacy [s.
If a light source emits one candela of luminous intensity uniformly across a solid angle of one steradian, the total luminous flux emitted into that angle is one lumen.
For the former design case, [13,14] proposed a minimum-sidelobe-based method to design the transmit beampattern in steradian space.
The helix antenna provides AR of nearly unity over the whole 47 steradian solid angle except at and around nulls, and to the best knowledge of authors this antenna provides maximum solid angle polarization beamwidth (for AR [less than or equal to] 3 dB) in the class of omnidirectional resonant antennas in elevation plane at any azimuth angle.
Provided that the surface of the flat sensor is held perpendicular to a line from the source to the sensor, measurements with a flat sensor can also be used to estimate fluence rate provided three conditions are met: (1) there is a single UV source; (2) reflections from room surfaces, particularly those that are not within the 2[pi] steradian viewing angle of the flat sensor, are not significant; and (3) the sensor is not too close to the source.
12] hertz and that has a radiant intensity in that direction of 1/683 watt per steradian.