In a message dated 4/21/02 9:18:37 PM US Mountain Standard Time,
SRL311guy@aol.com writes:
> In the
> response of the human eye, blue is the last color to fade (to be seen) in
> dimming light, while red is a color that doesn't cause a pupillary response
> and disturb night vision.
To further that explanation:
Blue light has a significantly shorter wavelength than red or yellow light.
Because of this it will actually focus ahead of the retina, and blue things
will be slightly out of focus if there is any other illumination at all.
Traditional shooting glasses, and cheap TV sunglasses use a yellow lens to
eliminate much of the blue light and thus eliminate 'glare'.
This is especially true at night when the eye is opened up as far as it
will go to admit as much light as possible (Think photography 101 - the
larger the f stop, the smaller the depth of field). Blue lights at night
seem more visible because of 'glare' rather than illumination.
Find a store front that has blue neon, or blue illuminated letters, at
night and you will find that you have a hard time focusing on it. And, that
if you do manage, when you turn around and look across the parking lot,
everything else will be out of focus for a while.
As to the legality of them, HVSS108 (federal) specifically reserves red
lights displayed to the front and blue lights displayed in any direction to
police and emergency vehicles only, making blue dot taillights, under car
neon, and the 'wAy KeWl RiCeRbOy' blue headlights illegal. Enforcement is up
to local authorities.
Mark, not
Laurie :-)
70 SPL311
AzROC
Chandler, AZ
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