WTB Deep Red LED Flashlight or build one for me

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Joshk
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Great info, thanks.
I’ve located some Cree 670nm on Mouser. I think that is the perfect color. Now I need a driver for my triple-emitter plan…

hank
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a very primitive three-receptor system (would you design the sensitivities of the green and red receptor so close to each other?)

People wondered for a long time why there was that odd gap* between blue receptor sensitivity and the red and green.

Surprise — that band is used both by the rods (night vision, and for motion and edge detection in brighter light)

and by the blue-green receptor (which regulates sleep, not used for vision)
http://panda.salk.edu/pdf/emergingrolesofmopn4.pdf

(This whole area is new and research is very active)

Age makes quite a difference, which the naked-eye astronomers talk about here:

And no, I didn’t know much about this ‘til I started poking around.
Every time I ‘oogle the subject there’s new information.

This page is kinda wonderful. Complexity upon complexity:
http://www.handprint.com/HP/WCL/color1.html#receptors

including some more info about the

Quote:
photopigment (melanopsin). These cells respond to light sluggishly, are less sensitive to variations in light (although they do adapt to light), and connect directly to thalamic and brainstem visual centers. They do not contribute to the visual image but regulate important light reflexes — the circadian rhythm, contraction of the iris, and melatonin suppression.

and also

  • Quote:
    Why 3 Badly Spaced Cones? …. the most interesting question is not why we have three rather than four cones, but why the three cone fundamentals are so unevenly spaced along the spectrum and unequally represented (63% L, 31% M and 6% S) in the retina. Our acuity to differences in color (hue and saturation) would substantially improve, and our visible spectrum would significantly expand, if the cone sensitivity curves were more evenly spaced and the retinal cone proportions were better balanced.
    ….
    … The answer appears in an important optical problem that arises when a large eye is made sensitive to a wide span of the spectrum: chromatic aberration…..

alpg88
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i’ve build about half a dozen lights with deep red, problem with exotic reds is that they do not illuminate as good as 620nm red, driven by the same current.

Joshk
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alpg88 wrote:
i’ve build about half a dozen lights with deep red, problem with exotic reds is that they do not illuminate as good as 620nm red, driven by the same current.

That sounds like a good thing, except that I imagine it only seems brighter because a second receptor (the green one) starts activating. I am sticking to 670.

foolioGrimz
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Does anyone have a link to color example chart comparing the different red colors?

hank
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One of these may help: do an image search, like this: http://www.google.com/search?q=red+LED+wavelengths&tbm=isch&tbo=u&source...

Color reproduction on a computer monitor (not to mention HTML encoding of colors on web pages) may be closer than you think, or not.

foolioGrimz
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Thank you, that was very helpful. I guess I wasn’t typing in the right stuff. It looks like the deep red would be better for saving night vision.

waterman74
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Richard at mtn is too busy right now to do a build. I have pmed 18 six fifty. We’ll see what he says.

Thanks

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