Finding true cyan LEDs

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saabluster

saabluster

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I just had a theory that I thought I pass by the crew here. I honestly haven't put much time into it to figure out whether or not I am off my rocker here or not but here goes. It's been a bit slow around here anyways.:D

I know many of you have been looking for true cyan emitters and they seem incredibly rare to say the least. I ordered some "cyan" rebels a while back and they were straight green. I was ticked off they can get away selling those as cyan. One thing that occurred to me was how the farther you move away from green the lower the lumen output of the LEDs generally are. The "cyan" LEDs I bought were the highest flux bin I could buy. In thinking about it I wonder if that would mean it is more likely to be at the green end of things. Maybe if I ordered low flux bin cyans I would be more likely to get a true cyan. Since none of the places I have seen allow you to buy based on the binning of the wavelength maybe this is a way to know without knowing. What ya think?
 
I'm not sure if your theory would work. Did the seller specify the dominate wavelength? At least with low powered LEDs, I notice the cyan ones tend to shift more green unless driven at full current.

I see SuperbrightLEDs has a cyan Cree X lamp rated 505nm. Their prices may not be the best, but they are a possible source for power cyan.
 
The "cyan" that is sold by nearly everyone is targeted at US traffic light "green", which is nominally 505nm. This used to be quite difficult to make "bright",but there is a lot of demand, so it gets development attention.

IIRC, there is a slightly bluer color used in Japan in traffic lights, or at least used to be? Perhaps Nichia has a product like that.

Sometimes, you can ask Future to find a specific color bin for you. We are all used to paying attention to white LED color space, but there is also a similar binning for color LEDs. It used to be easier to obtain these "non central" color spreads, but with improved process control, the production has gotten much tighter. Now you might have to buy a reel or more.

IMHO, there are some big holes in the standard LED color offerings at around 490nm and between "green" and "amber". (sort of like yellow)

There are a few companies that make LEDs in that range. Osram might have a version as they have a lot of options. Otherwise, it takes lots of searching.
 
JohnR66 said:
I'm not sure if your theory would work. Did the seller specify the dominate wavelength?
Click to expand...
I speak of Future Elec. I tried looking for cyan and I don't see where they have the cyan grouped into bins for wavelength. On Cutters site you can get the greens for instance binned very tightly. If only Cree still made cyan LEDs.

HarryN said:
The "cyan" that is sold by nearly everyone is targeted at US traffic light "green", which is nominally 505nm. This used to be quite difficult to make "bright",but there is a lot of demand, so it gets development attention.

IIRC, there is a slightly bluer color used in Japan in traffic lights, or at least used to be? Perhaps Nichia has a product like that.

Sometimes, you can ask Future to find a specific color bin for you. We are all used to paying attention to white LED color space, but there is also a similar binning for color LEDs. It used to be easier to obtain these "non central" color spreads, but with improved process control, the production has gotten much tighter. Now you might have to buy a reel or more.

IMHO, there are some big holes in the standard LED color offerings at around 490nm and between "green" and "amber". (sort of like yellow)

There are a few companies that make LEDs in that range. Osram might have a version as they have a lot of options. Otherwise, it takes lots of searching.
Click to expand...
505 is still in the green spectrum though. I also don't have the buying power to order full reels to get the bin I want. I'll look at Osrams offerings. Thanks.
 
What specific wavelength are you looking for?

'Cyan' to my eyes pretty much describes any cheap Cree 'blue' emitter. I've had some Lux IIIs even worse. Perhaps looking for blue bins with the longest possible wavelength would work.
 
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Just a quick search on cyan leds shows they are the most visible to the eye? Is that why they are desired?

Just curious, if you search XREBLU-L1-R250-00K01CT-ND on digikey, does it look promising?
 
netprince said:
Just a quick search on cyan leds shows they are the most visible to the eye? Is that why they are desired?

Just curious, if you search XREBLU-L1-R250-00K01CT-ND on digikey, does it look promising?
Click to expand...

These will be too blue to me. Certainly not royal blue, but not really cyan either. Sounds like he needs something in the 490-500nm range if the "traffic light" green is too far into green. This odd tint may be tough to find. Better to mix two LEDs if application allows.
 
Mixing blue and green LEDs will result in dull saturation and other color problems. I have fully mixable RGB PARs, and trust me, running up the blue and green yields a muddy 'cyan' at best.

The LEDs linked above are 485nm, and this is close to the ideal where most tech sheets put true cyan. However, there's a lot of subjectivity involved as to what is actually preferred here. In any case, using a specific emitter with desired spectral peak is a much better than mixing.
 
blasterman said:
Mixing blue and green LEDs will result in dull saturation and other color problems. I have fully mixable RGB PARs, and trust me, running up the blue and green yields a muddy 'cyan' at best.

The LEDs linked above are 485nm, and this is close to the ideal where most tech sheets put true cyan. However, there's a lot of subjectivity involved as to what is actually preferred here. In any case, using a specific emitter with desired spectral peak is a much better than mixing.
Click to expand...
Agreed. Mixing two colors does not make them combine into a spectral output in the middle. It's not the same. Well I put through an order but for the XP-E version with the same code as they were actually in stock. I will let everyone know what comes of it when they arrive.
 
Seems that Luxeon had some nice Lux V cyan's several years ago. Just did some googling for Cyan pics, and mostly nil, either pics not showing up, or dead Photobucket. Here is a post with various colored LED Arc's, with some cyan shown. I suspect these are Luxeon's. Whoops, looks like some 5mm colors too.

Bill
 
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What would you guys recommend as a good host for one of these? I was thinking a jetbeam rrt0 would be nice, but its a little bit spendy. Easy to swap the emitter though...

I ordered two emitters also, looking forward to trying out cyan...
 
I found this to be an interesting read related to the subject...

http://www.visualexpert.com/Resources/nightvision.html

As illumination declines, the visual system starts conserving light in three ways. First, inhibitory responses weaken, and eventually stop. Second, inhibition is replaced by convergence, where the receptor outputs sum together to increase sensitivity but further reduce resolution. Third, there is more available photopigment as light declines. When light strikes a molecule in a photoreceptor, it "bleaches" the molecule, causing electrical activation that leads to a visual sensation. While in the bleached state, it is unresponsive to light. The more photopigment in a bleached state, the less available to respond to light and the lower the sensitivity. In dim light, very little of the photopigment is bleached, so the eye has greater light sensitivity. All of this occurs before and continues after the switch from cones to rods.

One effect of switching to rods, however, is the "Purkinje shift." During photopic cones vision, viewers are most sensitive to light that appears greenish-yellow. In scotopic vision, they are most sensitive to light which would appear greenish-blue during the day. (Of course, viewers can't actually see color in scotopic vision. It is incorrect to say that "people are most sensitive to blue light at night.") One main result of switching to rods is loss of most sensitivity to long wavelength colors (red).
Click to expand...
 
Well I now have the emitter and it is more blue than cyan. At very low currents it is almost a perfect cyan but turns more blue as the current increases. The search continues.
 
Hi

Wayne at the shoppe had some lux5 cyan emitters not long ago.

Cutter has some Cyan Cree XR on sale right now under special sale.

Dave
 
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