Radiance is defined by where the approximation holds for small A and Ω, L is the radiance (W·m-2·sr-1), Φ is the radiant flux or power (W), θ is the angle between the surface normal and the specified direction, A is the area of the source (m2), and Ω is the solid angle (sr). The spectral radiance (radiance per unit wavelength) is written Lλ and the radiance per unit freq ...

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Radiance, Radiance - Definition

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