Ouch! Never heard that one before. That's spooky.
If wars were run by people who actually use their brains, we'd all be in trouble!
It's interesting that the Sidewinder used an AM (amplitude modulation) reticle, which is a spinning optical disk that chops the incoming IR radiation into a modulated signal so that position information can be extracted using a single photo-detector.
More on reticles
We used the technique (upgrading to an FM reticle) up until the AIM-9R Sidewinder in the late 1980's. The technique was developed by the Germans in the latter stages of WW-II.
So if you're trying to come up with an alternate history that's sort of plausible, and considering that the Germans were already doing a lot of work on anti-aircraft rockets and guided missiles, it's a pretty easy leap to make.