The reason for Night Vision Goggles (NVGs) being green is primarily for 2 reasons.Originally posted by Trypsin
True eyes are less sensitive to reds, green is the most sensitive color, which is why night vision is in green. Which is probably why lots of cars come with green dash lights
1. Green Phosphor for CRTs is really cheap.
2. Lower power generation - to appear the same brightness, you actually have to pump out a lot more red light than you do green. ie 1 watt of green light is as bright (visible) as 10 watts of red light. When you are designing a system to be mounted on your head - you want the lightest weight - if you are only needing 1 watt - it is easier. (this is where photometric as opposed to radiometric units 'normalise' this so that you can compare easily)
Fighter cockpit displays and HUDs are green precisely because that is where your eyes are most sensitive. They went to great expense to develop a phosphor that is exactly the same wavelength as the eye's max sensitivity.
The problem with NVGs is that being green light - they ruin your natural night vision. You are using your cones in your eyes which are the high res colour receptors. To get your natural night vision (which takes about 30 minutes to get good) you have to get the lazy rods (which are not colour sensitive, but more responsive in the red end of the spectrum) to start working - so if you are wanting your eyes to be best adapted for night vision and most sensitive, you should use red light, so as not to shut down the rods and not stimulate the cones too much.
For info - the eyes response to red and bluey- purple light is about the same.
Sorry for the ramble - have spent a lot of time on this topic and reporting to a military board of inquiry after we lost 2 choppers and 18 guys in an NVG related crash.