On the other hand, the size of the emitting volume is irrelevant.įor uniform omnidirectional emission, the luminous intensity is independent of the distance from the light source – in contrast to the irradiance, which scales with the inverse square of the distance from the light source. by a lamp housing containing a reflector, the luminous intensity can become correspondingly higher for the same luminous flux. The luminous flux per unit solid angle (per steradian), as measured in a given direction relative to a light source. If the light emission is restricted to a smaller solid angle, e.g. In the simplest case, where the luminous intensity is independent of the direction (uniform omnidirectional emission), the luminous intensity is the luminous flux divided by sr. Cases With Uniform Omnidirectional Emission Note that the visual brightness of a light source is determined by its luminance, and not by its luminous intensity because it also depends on the size of the source. One candela approximately corresponds to the luminous intensity of an ordinary candle. The SI units of the luminous intensity are the candela = lumen per steradian (cd = lm/sr). The analogous quantity in radiometry (not consider the spectral response of the human eye) is the radiant intensity. 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. Photometry deals with the measurement of visible light as perceived by human eyes. The luminous intensity takes into account the spectral response of the human eye – typically for photopic vision, i.e., assuming sufficiently high light intensity ( luminance) for color vision. In photometry, luminous intensity is a measure of the wavelength-weighted power emitted by a light source in a particular direction per unit solid angle, based on the luminosity function. It is defined as the luminous flux per unit solid angle. The luminous intensity is a quantity in photometry for characterizing a light source. How to cite the article suggest additional literature Encyclopedia > letter L > Luminous intensity Luminous Intensityĭefinition: luminous flux per unit solid angleĬategory: light detection and characterization
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