ZEMAX
is a fully featured illumination analysis package.
You
can define as many sources, objects, scattering properties
and detectors as you like, and set the units to whatever
you prefer to use. ZEMAX uses both radiometric units (watts)
and photometric units (lumens, lux, phot, footcandles etc):
Any
faceted object can be a detector. There are also dedicated
detector objects which display coherent and incoherent irradiance
(power per unit area) or intensity (power per unit solid
angle). Here is one detector from the top screenshot showing
Watts/cm^2:
and
here is the same data presented as radiant intensity (Watts/steradian)
