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is_this_the_place t1_j6lds00 wrote

Reply to comment by Spiritual_Jaguar4685 in ELI5 why do your eyes adjust so fast to bright light but so slowly to darkness? by melig1991

Some headlamps have red and green lights — why also green??

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Veerand t1_j6mr05x wrote

I don't think I have seen one with green and red, only white (regular) and red.

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Spiritual_Jaguar4685 t1_j6msx3h wrote

Not an expert here. I believe certain colors of other lights can also preserve night vision. Low intensity green light does it to I believe.

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dan5280 t1_j6o5uo7 wrote

Most military night vision goggles have a green filter on them so you can use a green light and not have your goggles shut down. Particularly helpful in the cockpit if you're flying with goggles on and need to look at a map or something inside

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rcm718 t1_j6oazxi wrote

But why use a green light instead of red?

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dan5280 t1_j6obmno wrote

I'm not entirely sure, but I do know from experience that red light will blow out your goggles (like if Joe infantryman in the back wants to try and read his map in flight). I assume it's something to do with wavelengths but I'm no scientist.

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rcm718 t1_j6ogt3d wrote

I mean, I am a scientist and I don't know. ¯_(ツ)_/¯ But like you said, maybe it has to do with the goggles being sensitive to infrared and red is close enough in wavelength to infrared that it can overload the gogs.

As long as we're speculating - here's a substantially unsubstantiated web page about it. It says green light at low levels also doesn't mess up night vision. And green can be used at lower brightness, has better contrast and color discrimination, and is better for common tasks like reading maps.

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