Abstract
When the absolute value X = ∫Xμ(μ)·dμ of incident radiation cannot be obtained from the output V = ∫Xμ(μ) · RX(μ) · dμ of a selective instrument, with nonuniform responsivity RX(μ) = Vμ(μ)/Xμ(μ), because the incident distribution Xμ(μ) is not known, recourse is had to various normalization methods. There is continuing confusion over the significance of a normalized quantity Xn = V/Rn and its relationship to the absolute value X. This problem, first discussed for the familiar spectral parameter μ = λ, is analyzed generally for different normalization methods, in terms of any radiometric quantity X, distributed as Xμ(μ) ≡ dX/dμ with respect to any radiation parameter μ. Peak normalization, most often used, gives conservative, lower-bound values. Bandwidth normalization is also discussed. It is recommended that units for all normalized quantities, such as lumens for photometric quantities, be distinctively designated, e.g., normalized watts or [NW], to emphasize that, without at least the relative incident distribution xμ(μ) = Xμ(μ)/C, they cannot be directly converted to absolute quantities.
© 1973 Optical Society of America
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