Also contains definitions of: radiant energy fluence rate, spherical irradiance
https://doi.org/10.1351/goldbook.FT07376
Total @R05046@, \(P\), incident from all directions onto a small sphere divided by the cross-sectional area of that sphere. SI unit is \(\text{W m}^{-2}\).
Notes:
- Mathematical definition: \(E_{\text{o}} = \frac{\text{d}P}{\text{d}S} = \frac{\text{d}H_{\text{o}}}{\text{d}t}\). If the @R05046@ is constant over the area \(S\), \(E_{\text{o}} = \frac{P}{S}\). Equivalent definition: \(E_{\text{o}} = \int_{4\pi}L\text{d}\varOmega\), with \(\varOmega\) the solid @A00346@ of each beam passing through the given point on the surface and \(L\) the @R05037@ of the beam at that point.
- Fluence rate is identical to spherical irradiance and reduces to @I03254@, \(E\), for a parallel and perpendicularly incident beam not scattered or reflected by the target or its surroundings.