Hello David,

thanks a lot, this definitely nails the problem I had. Anyway I found the operator DMVA which is used to constrain the clear aperture/Mechanical semidiameter to a certain value. That means taht when called it gives information about the clear aperture diameter that is the footprint diameter.

Are there some warnings in using it?

Thanks

Gabriele

Hi Gabriele,

That is a really good solution as well. Since DMVA is a native operand, it’ll probably be quite fast. However, note the following issue:

In this example, I’m looking at the lens in Surface 3. DMVA will report 30.0 because the off-axis field is decentred (the beam footprint diameter is float by STOP size = 20.0). However using X/Y max minus X/Y min would give you the true footprint of your beam, the marginal ray calculations suggested by @Mark.Nicholson would also give you the true footprint of your beam.

I hope that makes sense, take care,

David

Hey Gabrielle,

Is the surface you are worried about in a caustic (a highly aberrated space) such that the marginal ray is not the limiting ray? 

If so, you could get the REAX of several rays and then use MAXX to get the largest of them.

• Mark

Hello

thanks  David to warning me about the problem concerning off axis systems. 

Also thanks Mark for suggesting the alternative REAX. Since I have not heavy aberrated Optics  I think the use of DMVA could make the job but I keep present your suggestion.

Best regards stay safe