Why is red light used for night vision? Why not yellow or other colours of light?
In: Technology
Red light is used to help prevent loss of night vision because there are less red receptors in the human eye. Only the red receptors lose their sensitivity, leaving the green and blue receptors unaffected and retaining their dark sensitivity.
However, it has since been found that the levels of light affect night vision more than colour. That’s why aircraft cockpits don’t use red light in the dark as it makes little difference in practice.
Night vision takes about 10 minutes to develop and the best way of keeping it working is to cover one eye while working in light, uncovering it when back in the dark again.
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