WTB: Infrared lenses (Germanium, Silicon, ZnSe, GaAs)

[Spirit532]

If you have any spare longwave infrared lenses you wouldn't mind parting with to help a thermal imaging nerd, please let me know.

Ideally I'm looking for the biggest(around 70-200mm) and smallest(around 8-15mm) adapters to go on top of a regular lens, since I have a FLIR T440bx that has a built-in lens and adapter mount(not a fully removable lens), but I am open to anything longwave in general, as it's possible to convert a complete lens to an adapter, thanks to infrared optics staying very primitive.

My plan is to use a telephoto lens on a PTZ mount to do >100MP panoramas, and the wide for closeup work and art videos.

Obviously, any offer is welcome.