--- RampantNM@aol.com wrote:
> I'm confused, although some would say that's not hard to do. When
> I wear
> red tinted sun glasses, it seems to filter out the red, so
> landscapes appear
> greener. I thought a red lense would filter the red light.
Hmmm... A red filter should exclude all colors but red.
If you put on red sunglasses, you should see only the red
component of the light. If you're putting on red glasses
and seeing green, that's a medical condition I'm not
competent to comment on! :-)
There are dichroic lenses which not only pass one primary
color, but reflect the others. These are used alot in
optical color splitters, like the mirror/prism arrays in
television cameras to split the image up for the red, blue
and green sensitive CCDs. So, for instance, a red dichroic
filter would pass red and reflect blue and green. The
*reflection* from such a filter would consist of the blue
and green components of the spectrum, and would of course
look much greener than the original image.
> Do they filter the
> white light out of our current incandesent bulbs? Isn't "white"
> light a combination of all the colors?
Yes, it is. So you can't "filter out" white light except
with an opaque (or to partially filter it, a neutral
density or "pure gray") filter. The red lens on a tail
lamp allows the red component of the white light to pass
and absorbs the other colors, converting them to heat.
David Breneman david_breneman@yahoo.com
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