We have an KBA which describes some related tools and sample file made by my experienced colleague Sandrine.
One important tool is the NSC Sag Map, you can find more information here:
Besides, Steven has highlighted some tips:
About stray light analysis, you can refer to：
This is what Lumerical can do with HUD：
The coating can be modelled using table coating：
We have a webinar in Chinese：
Sometimes the system is designed reversely. In this case, the relative illumination and distortion are inverse. If you want to check the relative illumination at the “object surface”, you can refer to this article.