Interesting. They estimate 8 bits per hour, and are only doing bidirectional. I bet it's more like 16 bits per hour for exfil only, and with a much better range with an infrared sensor (which, interestingly, can be created by carefully scraping off the microlenses from an ordinary CCD, I recently learned).
That's a much shorter wavelength part of the spectrum than thermal imagers operate in, even though it's also infrared. CCDs pick up the kind of infrared that IR remote controls use.
