IEVref:845-25-088ID:
Language:enStatus: Standard
Term: basic law of radiometry and photometry
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Definition: general principle that, in the absence of losses, the elementary radiant flux or luminous flux, dΦ, between two elementary areas dA and dA′ defining an elementary beam is proportional to the elementary projected areas dA cos θ and dA′ cos θ ′ in the direction of the beam and inversely proportional to the squared distance, l, between the areas

Note 1 to entry: The basic law of radiometry and photometry is expressed by

dΦ=L dAcosθd A cos θ l 2 MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHX garuavP1wzZbItLDhis9wBH5garmWu51MyVXgaruWqVvNCPvMCG4uz 3bqee0evGueE0jxyaibaieYdi9WrpeeC0lXdh9vqqj=hEeea0xXdbb a9frFj0=OqFfea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXd bPYxe9vr0=vr0=vqpWqaaeaaciWacmGadaGadeaaeaGaauaaaOqaai aabsgacaWGMoGaeyypa0JaamitaiabgwSixpaalaaabaGaaeizaiaa dgeaciGGJbGaai4BaiaacohacqaH4oqCcqGHflY1caqGKbGabmyqay aafaGaci4yaiaac+gacaGGZbGafqiUdeNbauaaaeaacaWGSbWaaWba aSqabeaacaaIYaaaaaaaaaa@4E08@

where the proportionality factor for this geometrical condition is equal to the radiance or luminance, respectively, within the elementary beam.

Note 2 to entry: The basic law of radiometry and photometry is based on the geometric extent.


Publication date:2020-12
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