View Full Version : Glasses for Colour Challenged Pilots?

8th Feb 2013, 15:46
If the glasses just produced for colour blind people (Red, Green) actually work will they be able to get PPL and Commercial licenses? After all you can get/keep your license if you have to wear prescription glasses.

green granite
8th Feb 2013, 16:08
They only enhance red/green colours, which begs the question why they should diminish yellow, a person red/green blind shouldn't be able to perceive yellow.

8th Feb 2013, 16:33
I am daltonic. Can't see the Ishihara tests at all, failed the lantern test miserably. However I can distinguish red and green in every day life, in fact part of my job, at one time, was designing colour for furniture!

It was, perhaps, almost the ultimate stupidity that the people who instituted the colours for aviation chose the actual wavelengths that are not visible to daltonics like me. (And I do know that they were descended from those for maritime navigation which were probably in use before colour blindness was properly understood.)

In my case changing the wavelength slightly of eother the blue or green would probably allow me regular colour perception but I don't understand how the glasses are supposed to work for people with full red green colour spectrum deficiency. If your cones can't see the red/green wavelenths how could the glasses allow them to do so.

If I was to wear green glasses I would be able to do the Lantern test because I would see the greens and whites but not the reds so I could call the colours for the difference however wearing the glasses out at night wouldn't be useful because I wouldn't see the red nav lights at all!

These glasses are claimed to allow us to see red and green 'vividly.' If they do how could we be refused a license. (Won't help me, I'm 68, but it might help my daughter's children if necessary. (None of my sons are colour blind, it's passed down the female side. My maternal grandfather was colour blind but not my mother.)

Loose rivets
8th Feb 2013, 19:56
If your cones can't see the red/green wavelenths how could the glasses allow them to do so.

I don't know, but when a photon enters glass, all sorts of things happen.

For example: Glass can be used in electronics as a delay-line. Indeed, old tellies used to have a glass block on the board for just that purpose. So, what's happening with these lenses?

My understanding is, the photons that leave the glass are not the ones that enter its surface.

UV filters, and glass in general, doesn't allow the creation of high energy photons, but some light is obviously 're-created' in the glass' structure.

It could be some bright spark has made a substance that replaces the incoming photon with one of a slightly different frequency. This wouldn't be a filter as such, but an energy modifier. I can't see how it would be able to increase the energy of a photon, but then, some recent advances have left me breathless. So who knows?

Loose rivets
10th Feb 2013, 07:28
Contributor "UV" in Yahoo answers puts it better than me.

(Shown as a physicist, optometrist.. .and educator)

Now to answer your question... [Engineer] is almost right... but.. glass's molecules, and electron orbits are structured is such a way, that when a photon hits an electron, and boosts it up to a higher level... that electron jumps back down, and emits another photon that has the SAME property as the original photon that hit it in the first place... that is, same energy, same angle.... So that it appears that the light passed through unobstructed.

The time that electron took to jump up (absorbing the photon), and fall back down (emitting the photon)... is the 'delay' time of light travelling through glass.... you see.. when the photon jumps from one electron (in one molecule) to the next electron (in another molecule)... it's travelling at 'c'.... the fact that light 'slows' down in glass (and other media).. is due to this 'delay' time.. of the electron absorbing and re-emitting the photon.