Now, inside we've got motion detectors,
INFRARED sensors...
The Big Bang Theory Season 3, Episode 13
What's up with the INFRARED cameras?
The Big Bang Theory Season 4, Episode 18
Run an INFRARED repeater,
photocell here, emitter here, easy-peasy.
The Big Bang Theory Season 1, Episode 2
The optics are great.
It's got INFRARED technology.
The Big Bang Theory Season 6, Episode 21