…that is to say, the “night vision” as seen through light amplification/near infrared devices.
I seem to recall that in the old days—well, in old movies and video games, at least—the output of such scopes was seen as red-tinted.
Is there some sort of complex, technical or optical reason for green-tinted night vision? Or is green just easier on the eyes than red, or plain black and white?
From what I’ve read, and thissite would back me up, human eyes can discern more shades of green than any other color.
Some explanations of human colour vision: 1, 2, 3, 4. In short, human eyes are most sensitive to shades of green, and the least sensitive to shades of red.
Incidentally, red light is used in submarines to preserve night vision while still providing visibility.
Unless, of course, you are colorblind/color deficient in green.
Some cars now have a couple of very dim red bulbs to illuminate the central console so you can see the controls a bit easier.
I think the first image-converter tubes used the same phosphors as old oscilloscopes: zinc sulfide. It flouresces yellowish-green.
If one was a chemist designing a new phosphor material to give out maximum light for minimum electron flux, perhaps some phosphors are more efficient than others? The green color might not be based on human eye spectral response, it might also depend on which chemicals are efficient electrical/optical converters.
Broomstick, green colorblindness is among the most common, iirc. I know of a few people who have it.
What would nightvision look like to them? Besides not being green, what disadvantages would it pose?
Maybe like… night?
Yes, I’m aware of the commonness of it, and you can add me to your list of “sufferers”
It depends, because “colorblindness” is not just one entity but several.
There are people who literally can not see “green”. To such people, green lights are typically perceived as white lights - they would be dimmer in comparison to a truly white light, but that would not be noticable except in comparison. Or, in some circumstances, the green light might be perceived as yellowish or bluish in color. So they would still percive light and images in such a system using green phosphors.
More common is color deficiency - the person perceives green, but not as well as a normal person (I’m in that category). To such a person, “green” as a color does exist, but pastels, or shades of green edgeing towards another color, might be “off”. For example, I own a winter coat that normally sighted people see as green. To me, it is brown. The green starboard lights on ships and airplanes usually appear blue to me. Emeralds are usually green, but sometimes they look blue to me. But grass is green, and so are trees and other leafy things.
(One common question I get is about traffic lights - in most cases, the green light does look green to me. When it doesn’t, it looks blue. I don’t have problems distinguishing the lights since what’s really important is that I reliably distinguish the “stop”, “caution” and “go” lights, not what color I call them or perceive them to be)
When I’ve seen representations of night vision systems I do see them as green. It may be that my color deficiency is not severe enough to have an impact in my use of such a system. Someone with true “green absence” may or may not have a problem - they may perceive the light as white or grey, but still see enough information in it that they can use it as ably as anyone else. I think the only definitive way to know is to assemble a group of folks with various color vision deficiencies and do some tests.
It is also possible that the colorblind may have an advantage over the normally sighted. Those who are colorblind, particularly the more severe forms, tend to rely on contrast, texture, and other non-color clues more than those with normal color vision. With night vision being monochrome, those used to relying a great deal on color cues may be at a disadvantage compared to those who are not so reliant on them.
How hard would color night vision be?
Pretty hard. You’d add a lot of unnecessary complexity to the device and seriously degrade its resolving power. Night vision equipment, by its design and nature, dedicates its power and resolution to increasing the perception of light, not divvying it up to colours. The lower the light, the harder it is to detect colour; that’s why when you see astronomy photos they’re in colour, but when you look at it yourself in a telescope it’s all white.
gentle, we used red lights in the Army to protect night vision too. We’d mask our flashlights with red filters. The tactic is also used by astronomers. (In the Army it also has the benefit of reducing the distance at which the enemy can see you using a flashlight.)