Turquoise LED, advantage?

What's the point of turquoise LED's? Just got an Arc AAA with turquoise LED and I'm curious what the intended use for it is. Thanks!

I know that my favorite color on the original photon lights have always been Turquoise. It has a brighter, and a wider beam than the white ones.
These days, LRI calls them "night vision green".

I believe that it is suppose to help protect your night vision.

I don't know of any other advantage to it other than that.

Flashlightman

Well, compared to a white AAA this thing is barely visible. Battery might be cold (just came in from shipping), and it may need a fresh one, so I'll try again when it warms up).

I also have an ARC AAA in turq. It is hidiously bright. I am also very partial to other green and green/blue lights.

Let me see if I can lay this out. Someone will correct my mistakes.

There really is no true-white LED. What we call white LEDs are really blue LEDs that have been doped with a phosphor coating to make them emit a whitish light. This conversion means that the 'white' LED will not be as bright as the blue LED it was made from -- although it WILL use the same amount of energy. Typically green LEDs are ~70% brighter than white LEDS for this reason.

Point One: Colored LEDs are brighter than white LEDs using the same amount of energy.

Also, the human eye is more sensitive to various shades of green than any other color.

Point Two:
Regardless of power consumption, a green light will always seem brighter than a white light driven to the same output because the human eye is more sensitive to green light.

So one of the answers to your question is that it's a double whammy. The greenish LED is both brighter than the white LED and it may be used to greater effect by your eyes.

Having said that, green is no good for color differentiation but it cannot be surpassed for shape recognition.

These factors add up to some weird sums. For example, everyone knows that the Infinity Ultra is twice as bright as the old Infinity. That is true when comparing white vs white -- but my favorite Infinity is the one with a green LED. The green Infinity is much closer to the brightness of the white Infinity Ultra -- but the old Infinity gets 40 hours on one cell. /ubbthreads/images/graemlins/grin.gif

I usually EDC a NightCutter Sport with the five green LED head. I use green light for almost every task that does not require color recognition. Bright light and longer run-times. It has kind of grown on me.

I've also read that animals are not spooked by green light.
While green lights won't preserve your dark adapted vision, they are popular with the military because night-vision equipment is designed to filter out blue-green.

DB - the turq AAA should be way brighter than the white but will probably have a trashyer (?) beam. Scotch satin tape will smooth it very well, but obviously won't stay attached during hard use.

The turq photon has become my keyring carry and the AAA turq my around the house light. Altho it doesn't preserve the night vision as well as the red, it does seem to be better than white altho much brighter.

I also picked up a Peak 1led 2xN cyan that is brighter than the AAA but considerably larger.

I swapped to a different battery and it is pretty bright. I don't have my white AAA to compare, but it's infinitely brighter than the closeout, single LED AAA from Peak (not the hi-power version currently being sold), so I guess I see what you mean about it being bright. Very trashy beam, though. Why are colored beams such low quality compared to white?

The AAA is noticably brighter with a lithium batt than with an alkaline.

I'm also a fan of turquoise, for the reasons stated above. It's among the brightest, brighter than the white LEDs, when it comes to those little 5mm LEDs (don't know if that still holds true for Luxeons). In addition, it's the "closest" to white, to my eyes, so turquoise is easier on the eyes than the other bright colors (blue and green).

Had a MadMax Turq once. I got rid of it as the REFLECTED light was so bright it hurt MY eyes!!!

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DharmaBum said:
...Very trashy beam, though. Why are colored beams such low quality compared to white?

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I'm not too keen on the actual mechanics of all of this but in my 'reality map' it seems that perhaps the phosphor coating diffuses the light somewhat on the white ones, whereas you're getting the straight product 'right off the die' with the colored ones, I dunno. This would be a good question for Mr Museum.

There also seems to be a great variation in the holes/artifacts of colored LEDS. I'm not as twitchy about rings/artifacts as some are but MOST of my lights use colored LEDs and I notice a HUGE variation -- even on the same color and model light from the same company.

On another tack...from the scotopic/photopic sensitivity charts it always looks like ~green should be brighter than ~turq -- but I find the turq lights to be really bright. Aside from the really bright ARC turq, I also have a prized CMG Infinity in blue/green that smokes all three (or four?) of my old green Infinities. I really don't understand this at all...

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Why are colored beams such low quality compared to white?


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The phosphor covering the blue LED die smooths out the beam.

The die of a colored LED is bare, so light emitted is emitted from a few surfaces, reflected off some surfaces, and shadowed by the bond wires. It's a complex emitting surface, and is prone to producing rings and splotches.

The phosphor in a white LED is a (relatively) smooth surface, so is much more uniform in emitting light. In white 5mm LEDs and low dome luxeons, the phosphor is more of a glob, covering a large part of the die and reflector cup, and is a larger, more circular surface producing light, so it tends to be a wider smoother beam, and more uniform. A high-dome luxeon has a square phosphor deposit, so it is still smooth, but optics will tend to produce a square beam pattern.

In contrast, for a 5mm colored LED, you get direct light from the surface of the die, plus some reflection in a ring from whatever light reflects from the reflector cup, which explains the ring/dark ring/spot that you see with a lot of colored 5mm LEDs. The die has a rectangular emitting surface, often with the corners chopped off where the bond wires connect.

With a colored luxeon and an optic, you see the grid pattern of the Luxeon die projected forward - there is a dark ladder-like shadow cast because the die of a Luxeon has a grid of opaque conductors over top of the emitting junction, shadowing some of the light produced. In a white Luxeon, that ladder pattern is nearly eliminated because the phosphor is a uniform surface and mostly makes up for the non-uniform pattern of the die underneath.

Both my blue multi-LED lights, an Inova X5T and a 7 LED Peak McKinley, have beams that are very visible shooting off into darkness; moreso than my green LED X5T and my green 5 LED Nightcutter Sportlight. I prefer the blue ones for that reason alone. Also, the little single 123 cell McKinley (high power) smokes the X5T.

I am a pilot, and use the turquoise photon freedom on my night flights. Supposedly, the turquoise is the brightest photon.

The turquoise color is easy on your eyes, and still allows you to see "red" on sectional and IFR enroute charts. Red LEDs obscure red printing on the charts.

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Also, the human eye is more sensitive to various shades of green than any other color.

[/ QUOTE ] Then why do electronic signs on roadways and appearing on newer transit vehicles seem to be going with amber/orange? I figured that must be the most sensitive color. I guess amber is related to green, but then red is used a lot too.

I beliene that the Turquoise LED, is more efficient than
a white one with the same amount of lux

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EricB said:
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Also, the human eye is more sensitive to various shades of green than any other color.

[/ QUOTE ] Then why do electronic signs on roadways and appearing on newer transit vehicles seem to be going with amber/orange? I figured that must be the most sensitive color. I guess amber is related to green, but then red is used a lot too.

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I don't know. The selection of colors for highway signs is a very complex process. There are more GREEN freeway signs than any other color. As I said, I don't claim to understand it. The charts I've seen ALL show that the human eye is more sensitive to green light. That is the reason the displays on night-vision equipment are green -- it's easiest to see.


While there is nothing particularly definitive about the above graph, it IS representative of a very large body of thought on this subject which may be corroborated many places.

Look Here

Or Here

Or Here

I have never seen anything that would indicate that the amber/orange part of the spectrum is easiest to utilize by the human eye. Everything that I see on this subject indicates that the eye is most sensitive to GREEN -- perhaps a yellowish green -- but a GREEN, nonetheless.

This is why I'm so confused about turq. From the published data, the brightest light should be a yellowish green and yet I keep seeing these turqs that seem to be the brightest in the real world. And turq is way over on the blue side of green.

/strokes chin, scratches head

I tried matching the spot from a green X1 with a white X1, and the result was cyan. This looked cool and was really bright.
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Free E.T.

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I don't know. The selection of colors for highway signs is a very complex process. There are more GREEN freeway signs than any other color.

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Well, the green signs are reflected light, while the amber electronic ones are directly emitted. Perhaps green is the most visible reflected or something? (And the roadway signs are an almost bluish green)

Amber penetrates fog and rain best. Thats why fog lights used to be amber until the marketing people changed them to white and they aren't really used for 'fog' anymore.

Oh, and Sub, I agree. Green is definitly brighter than cyan in LEDs. People just like cyan better for some reason. But it has nothing to do with being brighter than green. My green Keymate is amazingly bright for a 5mm LED. Green definitely looks good to me. /ubbthreads/images/graemlins/icon3.gif

I still want to make a green 5w 'tactical' light... /ubbthreads/images/graemlins/cool.gif

Mark