The radiant intensity should not be confused with the optical intensity as used in optical physics. 1-Day Acuvue Define Radiant Chic Contact Lenses are an advanced lens that complements rather than masks the iris to improve the look of the eyes. The radiance can be considered as radiant intensity per unit emitting area. In contrast to the radiance, the emitting area does not matter for the radiant intensity. Because the radian is based on the pure idea of 'the radius being laid along the circumference', it often gives simple and natural results when used in mathematics. The radiant intensity is relevant, for example, for calculating how much optical intensity impinges a photodetector placed in some distance from the light source. In case of isotropic radiation (i.e., with constant radiant intensity), the total radiant flux is simply 4 π sr times the radiant intensity. Generally, the radiant intensity depends on the observation direction, and the total radiant flux is obtained by integration over all directions. The total radiant flux of a source with uniform omnidirectional emission (i.e., and intensity not depending on the direction) is Φ = 4 π I.Ī related radiometric quantity is the spectral intensity, which is defined as the radiant intensity per unit optical frequency or wavelength interval. The corresponding photometric quantity is the luminous intensity in units of candela (cd) = lm/sr.Īt a distance d from a source with radiant intensity I, an area element with its normal direction at an angle θ against the direction to the source receives an irradiance E = I cos θ / d 2. In the SI system, radiant intensities are specified in units of W/sr (watts per steradian). The term is mostly applied with the approximation of a point source, i.e., in distances which are large to the extent of the source.
It can also be applied to transmitted, reflected or received radiation. The radiant intensity I e,Ω (or just I) of a light source is defined as the emitted radiant flux per unit solid angle. Radiant intensity is radiant flux per unit solid angle.
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How to cite the article suggest additional literature Encyclopedia > letter R > radiant intensity Radiant Intensityĭefinition: radiant flux per unit solid angleĬategories: general optics, light detection and characterization, optical metrology