Difference between revisions of "Radiance"

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<div class="definition"><div class="short_definition">A radiometric term for the rate at which [[radiant energy]] in a set of directions confined  to a unit solid angle around a particular direction is transferred across unit area of a surface (real  or imaginary) projected onto this direction.</div><br/> <div class="paragraph">Unlike [[irradiance]], radiance is a property solely of a [[radiation]] field, not of the orientation of  the surface. The [[SI]] units of radiance are W m<sup>&minus;2</sup> sr<sup>&minus;1</sup>. In general, radiance depends on time, position,  and direction as well as [[frequency]] ([[monochromatic]] or [[spectral radiance]]) or [[range]] of frequencies.  Irradiance for any surface is the integral of radiance over a hemisphere of directions above or below  that surface. The photometric equivalent of radiance is [[luminance]], obtained by integrating spectral  radiance weighted by [[luminous efficiency]] over the [[visible spectrum]].</div><br/> </div>
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<div class="definition"><div class="short_definition">A radiometric term for the rate at which [[radiant energy]] in a set of directions confined  to a unit solid angle around a particular direction is transferred across unit area of a surface (real  or imaginary) projected onto this direction.</div><br/> <div class="paragraph">Unlike [[irradiance]], radiance is a property solely of a [[radiation]] field, not of the orientation of  the surface. The [[SI]] units of radiance are W m<sup>-2</sup> sr<sup>-1</sup>. In general, radiance depends on time, position,  and direction as well as [[frequency]] ([[monochromatic]] or [[spectral radiance]]) or [[range]] of frequencies.  Irradiance for any surface is the integral of radiance over a hemisphere of directions above or below  that surface. The photometric equivalent of radiance is [[luminance]], obtained by integrating spectral  radiance weighted by [[luminous efficiency]] over the [[visible spectrum]].</div><br/> </div>
 
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Latest revision as of 15:56, 20 February 2012



radiance

A radiometric term for the rate at which radiant energy in a set of directions confined to a unit solid angle around a particular direction is transferred across unit area of a surface (real or imaginary) projected onto this direction.

Unlike irradiance, radiance is a property solely of a radiation field, not of the orientation of the surface. The SI units of radiance are W m-2 sr-1. In general, radiance depends on time, position, and direction as well as frequency (monochromatic or spectral radiance) or range of frequencies. Irradiance for any surface is the integral of radiance over a hemisphere of directions above or below that surface. The photometric equivalent of radiance is luminance, obtained by integrating spectral radiance weighted by luminous efficiency over the visible spectrum.