Re: More on lights.

terryc wrote:
On Fri, 26 Dec 2008 09:01:17 +0000, Keiron wrote:

I read the recent "bright lights" posting which got me in to a bit of research which in turn revealed that red lights are better for vision at night as they highlight obstacles with much less depth perception issues and, whilst highly visible to those around are much less blinding.

This is one of those areas of research that are interesting, but for
bicycle riders in the realm of sillness.

Think about it?
White light includes red light. Why throw away 7/8ths of the light?

The human eye has rod & cone cells. The rod cells are much more numerous and 100x more sensitive to light, but they do not distinguish color. The rod cell response peaks in the blue-green wavelengths, and is virtually non-existent in reds. Rods give us our night vision, but cone cells give us color and detail perception.

Some DIY bike light makers have deliberately used blue-green LED's claiming a many-fold increase in actual perceived brightness. Sounds good in theory. Red light can be used to preserve night vision because night vision is insensitive to it. Red bike lights for illumination of the road would seem to be a poor idea. Off-road, they'd make foliage look very dark, another disadvantage.

You don't have to "throw away" light with modern LED lamps. LEDs are quantum devices which naturally emit at a narrow wavelength. White LEds are typically made by either blending light from multiple monochrome LEDs or by exiting a blend of phosphors with a monochrome LED.

A monochrome blue-green LED certainly seems more efficient overall when factoring the spectral sensitivity of the eye.
.

Relevant Pages

  • Re: More on lights.
    ... White light includes red light. ... night vision, but cone cells give us color and detail perception. ... LEds are typically made by either blending light from multiple ... LEDs are available in a variety of wavelengths. ...
    (rec.bicycles.tech)
  • Re: More on lights.
    ... White light includes red light. ... Rods give us our night vision, ... us color and detail perception. ... LEDs or by exiting a blend of phosphors with a monochrome LED. ...
    (rec.bicycles.tech)
  • Re: More on lights.
    ... non-existent in reds. ... Rods give us our night vision, ... LEDs or by exiting a blend of phosphors with a monochrome LED. ... LEDs are available in a variety of wavelengths. ...
    (rec.bicycles.tech)
  • Re: More on lights.
    ... White light includes red light. ... Rods give us our night vision, ... us color and detail perception. ... One practical matter though is that there's a lot more interest in high power white LEDs than blue-green ones, so white LEDs in high wattage have become more available since the time of this article. ...
    (rec.bicycles.tech)
  • Re: Stocked up with 100w bulbs yet?!
    ... the persistence of vision makes the light look brighter ... It is a way of saving on electrical power. ... LEDs can be powered such that they emit continuous light (like if you power ...
    (uk.legal)
Loading