Car radar decetors are all so old-fashioned these days since the world is full of diverse threats. IR/Laser as well.
I want to build a modern RWR into my car and start profiling all the ELINT around me in 360 like "hey that's a volvo coming over the hill" rather than just beeps.
The sensor is just a 128x96 monochrome camera and it's fairly trivial to programmatically determine where IR lights are at in the frame. The processor just needs to scan through 12,288 pixels, find the center of a cluster of bright pixels and return coordinate. It's not a complex operation, but the devil is in the details: I suspect you would still need to overclock the hell out of it to process over 60fps. Manpads are fast with the Stinger clocking in at about mach 2. As the missile gets closer to the target, it wouldn't take much of a delay to screw things up.
So sure, if you spend the cash on a quality glass, you could do a ton with that sensor. It's probably years ahead of what was on the original Stinger, actually.
It might work, but the use-cases are extremely far apart here.
you don't need to check everything. let's say that spot is 10px wide, then you can check every 8th pixel meaning now you only need to check 16x12 px. then, maximum is gotta be in one of these 8x8 squares around shiny pixel, so you can sample middle of each to find out where it might be. then, scan that 8x8 square pixel by pixel to find maximum
this might be reason for not using absurdly good optics