Hello,

we are working with a 1200 EFL Earth-Observation telescope, trying to simulate the Earth albedo as a straylight source in non-sequential Zemax. So, ideally, the source should be represented as a lambertian scattering plane located at infinite distance. Approximating it as a very big plane at a very long distance (namely ~100 km) would result in very few rays striking the detector in the end. We also tried to use importance sampling and didn’t work out (maybe we didn’t do it properly).

On the other hand, placing the lambertian plane close to the telescope to ensure that it is “infinite enough” from the point of view of it, would result in undesired effects from defocusing in the veiling glare tests we want to perform.

Any hints on how to simulate this source? Should importance sampling work for this?

Thanks in advance.