We have an KBA which describes some related tools and sample file made by my experienced colleague Sandrine.

https://support.zemax.com/hc/en-us/articles/1500005577782-Which-tools-to-use-when-working-on-a-Head-up-Display-

One important tool is the NSC Sag Map, you can find more information here:

NSC Sag Map User Analysis – Knowledgebase (zemax.com)

Besides, Steven has highlighted some tips:

​  https://community.zemax.com/people-pointers-9/tech-tip-tuesday-working-with-freeform-hud-elements-1838

https://community.zemax.com/people-pointers-9/tech-tip-tuesday-setting-up-hud-systems-1815

https://community.zemax.com/people-pointers-9/tech-tip-tuesday-hud-with-fea-and-the-opticstudio-star-module-1785

https://community.zemax.com/people-pointers-9/top-tip-tuesday-hud-1761

About stray light analysis, you can refer to：

Stray light analysis for Head-up-Display - Part 1 – Knowledgebase (zemax.com)

https://support.zemax.com/hc/en-us/articles/4412788138387

https://support.zemax.com/hc/en-us/articles/4412793979539

This is what Lumerical can do with HUD：

Polarization-Sensitive Plasmonic Reflectors for HUD – SPEOS Interoperability – Lumerical Support

The coating can be modelled using table coating：

We have a webinar in Chinese：

https://mp.weixin.qq.com/s/s7BK_aeabHDtB2qHOU8E6Q

​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.

How to check relative illumination at 'object' surface (verify the relative illumination theory) | Zemax Community