# Cyan LED Uses?



## maxspeeds (Feb 5, 2009)

Ok, this may be a bit premature to post, as I just received a Q2H lux I *cyan* emitter today, and have been playing with it for only a few hours. Although the color is very beautiful and unique, I've been searching in and out of CPF for a practical purpose to Cyan light. 

So far I have found that it is useful for reading through Night Vision equipment. Something about our eyes being more sensitive to the blue-green spectrum and able to discern small numbers and letters alot easier when dimly light through this color.

Outside of Night Vision equipment, are there any other practical uses? I've also read that it is useful for hunting blood trails, but that doesn't seem to be accepted 100% by everyone. 

I can tell you one thing. the light really irritates my eyes. It irritates it more than white light. It seems it is very good at killing your night vision :naughty:. And, this makes sense since it completely lacks red (the best color for retaining night vision). Maybe it is good as a personal defense weapon at night? Hopefully someon can shed some light on the *Cyan* mystery lovecpf


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## space (Feb 5, 2009)

It kills your night vision because it emmits light right in the midle of your night vision responce, thereby lowering your eyes responce.


space


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## Daravon (Feb 5, 2009)

There are many color photographic processes that use cyan light. Traditionally, a color enlarger has cyan, magenta, and yellow lights that can be varied for appropriate color balance. Color photography has pretty much gone head-over-heels digital, but anyone looking to do optical prints would definitely be interested in cyan LEDs.


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## NateTheGreat (Feb 5, 2009)

If you study calcium levels in cells, the color is good for single wavelength fluorescent calcium dyes like Oregon Green Bapta-1 or Fluo-3!


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## greenlight (Feb 5, 2009)

You're not supposed to look *AT* the light!!!

Seriously, though, at very low levels the cyan light appears brighter than you would expect.


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## Greg G (Feb 7, 2009)

A member posted recently that his cyan light cut through rain very well. That's why he liked his. :candle:


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## Canuke (Feb 7, 2009)

space said:


> It kills your night vision because it emmits light right in the midle of your night vision responce, thereby lowering your eyes responce.
> 
> 
> space



The flip side of that is that if you are night adapted, you can illuminate *huge* areas with a one-watt LED. Just be careful not to hit something close by with your eyes open


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## 2xTrinity (Feb 8, 2009)

Canuke said:


> The flip side of that is that if you are night adapted, you can illuminate *huge* areas with a one-watt LED. Just be careful not to hit something close by with your eyes open


IMO in this case you're still better off with a plain old white LED. why? Not everything you're interested happens to reflect cyan light -- for example, red dirt, and many green tree leaves don't reflect cyan very effectively. 

When you are dark-adapted, your eyes really don't perceive colors (at the low levels of illuminaion I'm talking about) but in order for you to see _anything_ the light still needs to be at the correct wavelengths to be reflecting reflecting off of the surfaces you're interested in seeing, in such a way as to be creating useful contrast. This means a broad spectrum, rather than a single color is best. With red you'll see maybe the ground but not tree leaves. With green you'll have the reverse situation. With cyan or blue you'll see some flowers and white surfaces very well, but not much else. With white light, you can see _some_ light reflecting off of just about everything.

My very favorite light for seeing outdoors at night in very low illumination is actually 4000k white. It is actually solar powered, and is designed specifically for this purpose. It is called the moon.

On days when this "moon" doesn't work well enough for my liking, I use an LF2x, with a Neutral white LED Cree 5A LED, running at 1/3rd lumen. Enough to comfortably night-hike with with dark-adapted eyes, and diffuse enough that I don't dazzle myself.


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## BVH (Feb 8, 2009)

Here's a great "use" for cyan emitters.

Well, maybe it's not a "use" for them but it sure is eye candy. This is Mac's original photo of the light I bought from him. The four Q2HC "to die for" cyan emitters are just gorgeous when driven at 1 Amp+. All the green is gone, just pure Cyan.


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## Phaserburn (Feb 8, 2009)

I have a light called the Cyanator. It's a lux3 cyan direct driven from an 18650. Draws 1.4A for around 10 mins before settling into 1-1.2A range.

It-is-blinding!


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## Canuke (Feb 8, 2009)

2xTrinity said:


> When you are dark-adapted, your eyes really don't perceive colors (at the low levels of illuminaion I'm talking about) but in order for you to see _anything_ the light still needs to be at the correct wavelengths to be reflecting reflecting off of the surfaces you're interested in seeing, in such a way as to be creating useful contrast. This means a broad spectrum, rather than a single color is best. With red you'll see maybe the ground but not tree leaves.



Dark-adapted night vision doesn't perceive red at all, whether it's there to be reflected or not. Only the green-to-violet band is used. So, white is less effective in this context to the extent that it puts out red light.

Also, since our vision is monochrome anyway when night-adapted, the contrast that results from using a narrower-band emitter might work more to our advantage than the more even shades of grey we'd see with a wider-band emitter, since contrast becomes more important as an information source in monochrome vision.

That being said, it depends on the application; for general seeing purposes, cool white and pure cyan work equally well for night-adapted eyes. Warm white LED's and incandescents, which put more energy into the red band, less so.


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## Canuke (Feb 8, 2009)

Phaserburn said:


> I have a light called the Cyanator. It's a lux3 cyan direct driven from an 18650. Draws 1.4A for around 10 mins before settling into 1-1.2A range.
> 
> It-is-blinding!



I have an old Mr. Bulk "Eye-Cryin' Cyan" with a Lux 5 emitter, that still holds its own for output even with modern Seoul and Cree lights. It is a true cyan, sitting right on the border of where I start to call a light blue instead of green.

Current Lux III's of the same color nowadays, however, are binned as Q6JB *blue* emitters. I have several of these. The ones now sold as "cyan" (xxxC), including the Q2H I have in a modded Fenix, are all green (albeit "traffic-light" green) to my eye.

Funny thing, speaking of traffic lights, the green seems to be migrating towards the blue end of late; several of the new green LED's I saw in Canada last Christmas were really starting to look cyan instead of green, and I just noticed some similar cyan lights just down the road from here in Toluca Lake.


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## BVH (Feb 8, 2009)

The last 10" traffic light green LED module I looked at in the Traffic Signal maint shop for City of Burbank used two distinct colors of leds in it's grid. Relatively speaking, there was a green and a blue-green emitter arranged symmetrically in the circle. Very obvious up-close but when 20' away they blended into an overall blue/green light as compared to the original LED modules Burbank used which look green by comparison.


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## GarageBoy (Feb 8, 2009)

High visibility marker light?


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## Sub_Umbra (Feb 9, 2009)

maxspeeds said:


> ...So far I have found that it is useful for reading through Night Vision equipment. Something about our eyes being more sensitive to the blue-green spectrum and able to discern small numbers and letters alot easier when dimly light through this color...


Go back and re-read the posts that gave you that impression. The *exact opposite is true* and it's very well documented.

For the most part, NV gear can't see cyan *at all,* unless *it's pointed directly at* the sensor -- and the operators happen to be paying attention *at that moment.*


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## LukeA (Feb 9, 2009)

Greg G said:


> A member posted recently that his cyan light cut through rain very well. That's why he liked his. :candle:



That's because the back scatter looked dim because the eye is so insensitive to cyan.


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## greenlight (Feb 9, 2009)

LukeA said:


> That's because the back scatter looked dim because the eye is so insensitive to cyan.


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## Sub_Umbra (Feb 9, 2009)

LukeA said:


> That's because the back scatter looked dim because the eye is so insensitive to cyan.


The human eye is actually *pretty HOT* in the cyan range for scotopic vision:




The 490-495nm representation on the scotopic curve above is *near optimal* for shape recognition.

http://hyperphysics.phy-astr.gsu.edu/Hbase/vision/bright.html


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## LukeA (Feb 9, 2009)

Sub_Umbra said:


> The human eye is actually pretty HOT in the cyan range for scotopic vision:
> 
> The 490-495nm representation on the scotopic curve above is near optimal for shape recognition.



Your point being? Using a flashlight of middling brightness within 200 feet or so results in illuminances high enough to push the eye into photopic vision, making the cyan much less useful than white (or green, or yellow, or orange).


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## greenlight (Feb 9, 2009)

The original question is not what cyan is _*not good for*_, but what are its uses. 

I find it particularly pleasing, and I appreciate seeing it used in light shows. It appears very bright and is useful for effects with scattered beams like mirrored balls or other effects.

Not everything HAS to be white. Some people like to mix the colors up, and cyan is a good choice. 

I have an Inova X1.v1 that's waiting to be modded with a cyan LED. I'm looking forward to seeing that. I expect that it will appear really bright, and no one has ever seen that before, so it's a good conversation starter.


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## Sub_Umbra (Feb 9, 2009)

LukeA said:


> Your point being? Using a flashlight of middling brightness within 200 feet or so results in illuminances high enough to push the eye into photopic vision, making the cyan much less useful than white (or green, or yellow, or orange).


You're not connecting the dots. Cyan *IS* different than white light but if one *insists* on blundering around with it like most do with their white lights no advantage will be gained. The most common mistake most make with monochromatic lights is treating them as though they were white. Most are dissapointed, _as they should be._ Cyan has some unique properties that one will completely overlook if one tries to use it like the light that they're most used to -- _*the floody, bright, white light from the sun.*_

You may poo-poo the uses that others have actually mentioned for these lights for but that doesn't mean much to me. What is *your* experience base? How many cyan lights do you own? How much have you experimented with them? On your experience with what output levels and beam types are you basing your statements? By a quick, rough count I know that I have at least ten cyan lights. (ARC, CMG, Rigel, Pak-Lite, LRI and a ~one degree beam custom throw king made by IssacHayes. They have a broad range of both power and beam shape. I have one cyan light that gets turned on more than all of my other lights of all colors (including the white ones) *COMBINED.*

It should also be mentioned that the use of monochromatic light is very much a learned experience that can take years to hone and develop. Yes, there really is such a thing as a *"trained eye."* I've spent years and years working jobs where I had to rely on only monochromatic lights for most of my most difficult tasks. Years and years with red (at sea) -- years and years with blue (in technical theatre). I've only been using cyan for five years but my years of working with the reds and the blues have helped me a great deal in getting a handle on cyan.



LukeA said:


> Your point being?...



Here are some of the points that never occurred to you. First, use a tight beam -- the tighter the better. The tighter the beam the less light will be blown back at you. NOTE: when I say tight, I mean *really tight* -- not some tightish *yet spilly* beam that so many here at cpf claim to love. I'm not saying that there's anything wrong with that kind of beam, *only that it will not work in this application.* Be advised. Second, don't handle the light like an idiot. Care must be taken at all times to avoid any splash as much as possible. This will require both _thought_ and _practice._ I kid you not.

An archtypicial example of the above technique is used on ships all over the world *every night* -- with one enhancement -- separating the light operator from the observer. With the darkness adapted observer on the bow a hideously bright multi-bazillion CP spotlight is operated from another location. It must be controlled very carefully. The sea is a great example because one is often trying to put eyes on something small and far away but unlike on land -- there is very little to reflect the light back into the observer's eyes and ruin his dark adaptation. Having done this many, many times I can tell you that this is real. Though it sounds counter-intuitive, the observer's dark adapted vision may be preserved even while using a multi million CP beam. The key would be that one has to know what he is doing.

Although ship's spotlights usually have whitish beams, it makes a good example because it is very easy to grasp. These techniques also work very well with cyan for those with experience in that color range. The same techniques work the same way on land but they require more operator skill -- whether the observer is also the operator or not. Again, the real catch is that, like so many other things in life, _one must know what he's doing_.

It should also be remembered that many LEDs and flashlights in this color range have been selling and selling for years and years. It would be irrational to assume that all of those lights that *so many* continue to pay good money for really have no usefullness at all -- that all of those people who have bought _and continue to buy_ them are just stupid because some others think that this class of lights are useless. It doesn't work that way in the real world. Just because these lights are definitely not for everyone, that does not mean that they are useless. Personally, while I have no use for a jet engine, at least I will concede that they may useful to others whose _'experience base'_ may differ from mine.


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