Remember those giant shoulder-mounted video cameras from the late 70s, or early 80’s? This is the magic that made them work. When that brownish screen on the right is struck by photons, it emits electrons, which are picked up on the other end of the tube, and then translated into a video signal. Nowadays, we’d just use a CCD, but in the olden days, CCDs were crazy expensive, and had terrible resolution.
via Flickr http://flic.kr/p/eeXLvS