pybsm.radiance.functional.at_focal_plane_irradiance

pybsm.radiance.functional.at_focal_plane_irradiance(*, D: float, f: float, L: ndarray) → ndarray

Converts pupil plane radiance to focal plane irradiance for an extended source.

This is a variation on part of IBSM Equation 3-34. There is one modification: the IBSM conversion factor pi/(4(f/#)^2) is replaced with pi/(1+ 4(f/#)^2), which is valid over a wider range of f-numbers (source: John Schott,”Remote Sensing: The Image Chain Approach,” Oxford University Press, 1997). If the telescope is obscured, E is further reduced by 1-eta**2, where eta is the relative linear obscuration.

Parameters:

• D (float) – effective aperture diameter (m)

• f (float) – focal length (m)

• L (float) – total radiance (W/m^2 sr) or spectral radiance (W/m^2 sr m)

Returns:

E:

total irradiance (W/m^2) or spectral irradiance (W/m^2 m) at the focal plane

Raises:

ZeroDivisionError:

if D is 0