If a source which has a specific spectral profile is used for raytracing, how is the power, in FC or in lumen whichever, in each wavelength calculated?

If the SurfaceAbsorptance is assigned as the distribution on Property/SurfaceSource, how is absorptance of spectrum taken into account in calculating the power of each wavelength? How the numbers in

(1) weighting of each wavelength in RaytraceOption/Wavelength,

(2) flux power on Property/SurfaceSource aplet, and

(3) surface absorptance are handled?

Synopsis

Flux of Surface Source is controlled by 3 variables.

Solution

The 3 variables that control the emitted flux are:

• Flux value entered in Apply Properties / Surface Source dialog
• Wavelength weights selected in Raytrace Options / Wavelengths dialog
• Absorption values entered in Surface Property (can vary with both wavelength and angle)

If we enter a Flux of 100 Watts, and Wavelength weights of 1, .9, and .8 for the wavelengths .4, .5, and .6 um, then the emitted flux for .4 um = 100 Watts, for .5 um = 90 Watts, and for .6 um = 80 Watts. This result is the same whether the Angular Distribution of the Surface Source is selected as Surface Absorptance or not. When Surface Absorptance is selected, then the total flux determined for each wavelength is portioned out by an angle according to the Surface Property. However, changing the values for Absorptance in the Surface Property will not change the Total Flux emitted, only the angular distribution of the flux.