Something that occured to me recently...
There's a lot of mods to add night vision or thermal vision to power armor, but no lore to support power armor actually having either function (to my knowledge). Night vision is only known to exist in a select few pieces of gear (NCR Ranger headgear, Ghost people cowls, certain scopes) and thermal vision, to my knowledge, does not exist.
Then it occured to me that rather than simply being ignorant to it's existence, thermal vision may truly -not- exist within Fallout. Why? This makes sense because the US-Chinese conflict eventually boiled down to stealth dragoon armor vs. power armor, and if power armor were simply equipped with thermal vision, the chinese advantage would be absolutely meaningless.
So am I wrong? Is there any recorded incident of thermal vision existing within Fallout? Or could it very well be that thermal vision was never researched in the Fallout universe, and even night vision had limited support?