17-929

photon irradiance (at a point of a surface) [Ep]

1. quotient of the photon flux, dΦp, incident on an element of the surface containing the point, by the area, dA, of that element

2. equivalent definition: integral, taken over the hemisphere visible from the given point, of the expression LpcosθdΩ, where Lp is the photon radiance at the given point in the various directions of the incident elementary beams of solid angle, dΩ, and θ is the angle between any of these beams and the normal to the surface at the given point

        

Unit: s-1·m-2

Theme by Danetsoft and Danang Probo Sayekti inspired by Maksimer