Hi William,

Are you sure the total power is 7.3533 lumens in Zemax? I have 1000 times more when I run that model (“E+03”). In this case, you have a factor 2, which perhaps points to the detector not being cleared. That model file has the option “Retrace Source Rays Upon File Open”, so it may be that you trace without clearing the detectors and that double the power on the detector (it is added to the original ray tracing result).

Ways to test would be too uncheck the option, or run on another model. Or perhaps insert a clearing command. I think example 10 would be the one to look at. I am no python expert, but it looks that when I compare to your code, you should have a

NSCRayTrace.ClearDetectors(0)

in line 162 just after your call

NSCRayTrace = TheSystem.Tools.OpenNSCRayTrace()

Thanks for the response!

Yes, its definitly 1000x, I copy-pasted too hastily.

I will check for the detector clearing, but with my other test (which I cant share) I’d had 0.90W (api) vs 0.99 W (zemax), so its not an un-ambiguous doubling.

My mistake in this case, I was using polarization/ray splitting in one case and not the other.