Starlight scopes were in use during the Vietnam war; the M3 Sniper System was a backpack-carried power-source and processing source (in the sense that it did all the heavy lifting, not in that it provided any kind of computerized synthetic vision) for an IR scope fitted to the M1 Carbine. It was a bulky system but the rifle's effective range was about the same as the scope's night-vision capabilities so it was actually fairly decent.
I could foresee a county SWAT team out in the sticks finding them very useful post-apocalypse.
http://www.imfdb.org/wiki/Talk:M1_Carbine