Hi José,

Thanks for posting your question on the Community forums!

Regarding a grid-based NURBS surface, I do not believe we have a native surface which takes in a non-uniform spread of points other than those you’ve listed (Radial/Toroidal NURBS). The closest surface we have to a similar functionality is the TrueFreeForm surface, which is a superposition of different surface types (such as Standard, Even Asphere, Zernike Standard Sag), in addition to supporting a grid-based deformation of the surface.

This grid-based deformation is optimizable, as different points can act as variables. So, you can get localized surface optimization while leaving the rest of the surface unaffected. It does rely on this grid-like structure, though, so you’re not really having a non-uniform sampling of points. You can find more information on this surface in the article Using the TrueFreeForm surface​ for grid based freeform optimization. Note that this surface type is only available to Premium edition Subscription licenses.

Regarding your crashing with the Radial NURBS surface, this is certainly unexpected. I attempted to optimize a lens system with the Radial NURBS surface and did not experience any crashing, though it may be a case where you have a certain setup or complex model giving you issues. Do you begin the optimization with a starting point of some kind (some initial definition of the sag)? Or do you begin with a planar NURBS surface and let OpticStudio find a path forward for the sag (that is, all Zn terms begin as zero)?

It might help if we could take a look at the file itself, though I understand if it needs to be modified for any IP reasons. You can also feel free to submit a case to us through your Zemax Account on Zemax.com.

Let us know how these thoughts work out for you!