The Rayleigh-Sommerfeld diffraction theory is used to derive expressions for (1) the spectral irradiance on the surface of a hemisphere covering the aperture and (2) the spectral radiant intensity. For a uniform, noncoherent source-aperture, both calculations predict a cosθ angular variation, as is known to be the case of Lambertian sources. A cosine-fourth dependence of the spectral irradiance on a plane parallel to the aperture plane is also indicated.
Volume 94, 2020
Continuous Article Publishing mode
Click here for Editorial Note on CAP Mode