Ambient Radiation Sensors
“Unlike X-ray machines or radar instruments, the sensor doesn’t have to generate a signal to detect objects it spots them based on how brightly they reflect the natural radiation that is all around us every day.”
“It’s basically just a really bad tunnel diode,” he explained. “I thought, heck, we can make a bad diode! We made lots of them back when we were figuring out how to make good ones.”
First millimeter-wave detection systems, and now this. There’s some interesting research in remote sensing going on, and there are sure to be some cool security applications.