Thank you for the trouble you have gone to Harry, my thoughts went back to when we used to have
red night lighting below decks to prepare the eyes for night vision. Never really thought about the reason or theory, so asked Uncle Google who came back with this amongst others:
Blue versus red light for preserving night vision
I read on this forum an earlier post from a strong proponent of blue light for preserving night vision. As a pilot, I've been using red cockpit lighting for decades, and I know the FAA expended a lot of effort in biomedical research -- finally concluding red light was best.
So why the disagreement? I did some research and found the following three reasons for favoring red light over blue:
1) Producing dim blue light from an incandescent bulb that is dimmed by running at reduced voltage produces no blue light (in accordance with Planck's law), so in pre-LED days it was practically difficult to produce dim blue light without running an incandescent lamp at higher voltage (higher color temperature) and using a dense blue filter to make it dim.
2) The center of the human fovea, the part of the eye that you use to read printed materials and finely detailed charts, is blind to dim blue light:
https://www.osapublishing.org/josa/abst ... 57-11-1289
The rods can take over for blue-blindness in brighter light.
3) The rods, which we depend on to see dimly lit objects, are much less sensitive to red than to green or blue light. So at equal intensities dim red ambient light has much less of an effect on degrading night vision than does blue light. (Note the qualification: "at equal intensities." You don't need as much blue light to see in the dark.)
In the past, pilots had analog instruments and spent a great deal of time reading printed procedures and studying paper charts using ambient light. They needed to use the blue-blind parts of their eyes. Today, modern aircraft and boats frequently have "glass" cockpits with electronic displays with direct lighting where resolving fine details on paper are less frequently needed. Here, blue light is less of a hindrance, and producing dim blue ambient light with LEDs is easily accomplished. And since the blue cones are more sensitive than red cones, so you need less blue light than you need red to see nearby objects. If you don't need to read finely detailed charts, analog instruments and printed matter, you may be better off with blue light.
All of this assumes normal color vision. In the case of pilots, they are tested for color vision and are usually restricted no night flying if they have any color blindness. The FAA research completely disregards the night vision effects for color blind pilots.
The above comes from -
https://www.cruisersforum.com/forums/f1 ... 09780.html - which being a Forum has other comments below it.
Appears you are on the right track.