PhotonFanatic
Flashlight Enthusiast
Yes, the To Die For Cyan emitters.
Finding true cyan LEDs
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Yes, the To Die For Cyan emitters.
bshanahan14rulz
Flashlight Enthusiast
What is the Cyan you all are basing your ideal wavelength on? The big beefy argon lasers that peak at 488nm? Lithium or barium borate doubled solid state lasers at 473nm? Just curious, really.
Bin6 blue (around 488nm) is true cyan for me for most of the time, but bin1 cyan is perfect when my eyes are adapted to 2700k ambient light.
EDIT: After experimenting hundreds of times with different adapted states, I should say true cyan fluctuates between 485-495nm dominant.
EDIT: After experimenting hundreds of times with different adapted states, I should say true cyan fluctuates between 485-495nm dominant.
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PerryScanlon
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Funny! I noticed the same thing, and a lot of "yellow" LED's are in fact amber. Mixing amber and green in the right amount does make a nice lemon yellow, better than a red-green combo.
MikeAusC
Enlightened
If you're specifying the colour of LEDs away from 555nm, you need to understand the difference between specifying Peak Radiant Power Wavelength (as measured by an instrument) and Dominant Wavelength as perceived by the eye - the Power Curve modified by the Sensitivity Curve of the eye.
At red and blue there can be quite a difference, though not all LEDs have both figures available in the specifications.
At red and blue there can be quite a difference, though not all LEDs have both figures available in the specifications.
I always wondered why they didn't have anything between 570 and 590. Like what would 580 look like? The only pure yellow LED I've ever seen is a phosphor yellow Brookstone keychain light. And that was years ago. I often wonder why that never caught on on anything else.
Anders Hoveland
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Cree makes a 465-480nm LED, available as a 30 watt chip. And 505nm LED's are also common.
Could these two frequencies be used to fill in the cyan-indigo gap that exists in white phosphor LED's, to give a fuller spectrum?
These might complement the Phillips L-prize quite nicely.
Could these two frequencies be used to fill in the cyan-indigo gap that exists in white phosphor LED's, to give a fuller spectrum?
These might complement the Phillips L-prize quite nicely.
bshanahan14rulz
Flashlight Enthusiast
Never fear. InGaN is being pushed to higher and higher wavelengths. It's only a matter of time. Hell, some sample quantities of +500nm GaN resonators have already trickled down into hobbyists hands 
I contacted Future twice asking for full reel of bin1 cyan/bin6 blue emitters, but they never responded. However, I think I've found the last ray of hope here. The picture shows bin code J1CE, indicating its probably a bin1 cyan, also J means the lower flux bin 60+lumen, supporting saabluster's theory on the first post. These will be unsuitable(too blue) for the traffic signals, maybe that's why they are mounted on starboards. The MOQ was 48 but I still placed an order.
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FINALLY!!! Thanks a ton saabluster, it was your idea after all to go for the low flux bins. Got 48 bin1 cyan rebels (bin code J1C, i.e. 60-70 lumen, 490-495nm dominant, 2.79-3.03V, all measured at 350mA). I believe the slightly lower flux would not be noticeable in real life.
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:thumbsup: Your welcome. Glad that worked out for you.
Thanks to a color changing rainbow project, all of my J1C cyans are used up now! So buy in multiples of 48 from here. For bin2 cyan rebels, contact LEDSupply/StevesLED/TCSS etc. (They're not that rare after all)
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A new source
A new source for bin1 cyan leds has popped up: look here (and here for the 3S3P multichip version, but it has worse efficiency).
The good: Low cost alternative to the J1CE rebels. Color is indistinguishable to J1CE rebels at 700mA.
The bad: The Epiled chips are less efficient than the Lumileds ones (3.7V drop at 700mA). No polarity indication on the bare LEDs.
I ordered 7 of these but discovered 1 LED was missing just after opening the package. The seller was great, he refunded me $2.50 promptly.
Update Aug 2014: In about one and a half year, the silicone domes of these LEDs have started yellowing And they weren't even powered for more than 2 minutes in total. They were kept in anti-static foam boxes from mouser. Another drawback of cheap LEDs!
A new source for bin1 cyan leds has popped up: look here (and here for the 3S3P multichip version, but it has worse efficiency).
The good: Low cost alternative to the J1CE rebels. Color is indistinguishable to J1CE rebels at 700mA.
The bad: The Epiled chips are less efficient than the Lumileds ones (3.7V drop at 700mA). No polarity indication on the bare LEDs.
I ordered 7 of these but discovered 1 LED was missing just after opening the package. The seller was great, he refunded me $2.50 promptly.
Update Aug 2014: In about one and a half year, the silicone domes of these LEDs have started yellowing
And they weren't even powered for more than 2 minutes in total. They were kept in anti-static foam boxes from mouser. Another drawback of cheap LEDs!
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Re: A new source
Here is another source I found. I wrote to them and asked for the maker so i could look at a datasheet but they didn't reply. I will probably be ordering some though I don't have any 488nm to compare with.
http://www.aquastyleonline.com/products/Cyan-LED-3W.html
Here is another source I found. I wrote to them and asked for the maker so i could look at a datasheet but they didn't reply. I will probably be ordering some though I don't have any 488nm to compare with.
http://www.aquastyleonline.com/products/Cyan-LED-3W.html
Re: A new source
I already talked to them as the spectrum looked quite interesting, here's what they replied:
Hi,
thanks inquiry!!
the cyan led is more on green side.
but sorry we have not the datasheet on it because it is a customized product.
we can send you a sample to play with, you can just pay the shipping $6 (POST SERVICE 10-12days delivery)
best regards
***
I already talked to them as the spectrum looked quite interesting, here's what they replied:
Hi,
thanks inquiry!!
the cyan led is more on green side.
but sorry we have not the datasheet on it because it is a customized product.
we can send you a sample to play with, you can just pay the shipping $6 (POST SERVICE 10-12days delivery)
best regards
***
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Re: A new source
No, they didn't. The spectrum indicates (if its true at all) its a phosphor converted green (i.e. like the Osram's OSTAR for projectors)
My search for true cyan (485-490nm dominant) emitters is still on, till then I'll overdrive J1CE rebels on sinkpad with low duty PWM.
Update (July 2014): 490-495nm cyan Chinese LEDs in XP-E footprint are available on ebay now, for very little price. I've tested some more of them, one was not even properly reflowed.
(I was betting these to be 485-490nm dominant, which sadly they aren't. I'll might try my luck at Aliexpress.)
UPDATE(Nov 2014): Aliexpress sellers are selling blue LEDs covered with green phosphor, as 1-3W 'ice blue' 480-490nm LEDs. They are not true cyan, a pale skyblue with much lower saturation due to the wideband green emission from the phosphor.
No, they didn't. The spectrum indicates (if its true at all) its a phosphor converted green (i.e. like the Osram's OSTAR for projectors)
My search for true cyan (485-490nm dominant) emitters is still on, till then I'll overdrive J1CE rebels on sinkpad with low duty PWM.
Update (July 2014): 490-495nm cyan Chinese LEDs in XP-E footprint are available on ebay now, for very little price. I've tested some more of them, one was not even properly reflowed.
(I was betting these to be 485-490nm dominant, which sadly they aren't. I'll might try my luck at Aliexpress.)
UPDATE(Nov 2014): Aliexpress sellers are selling blue LEDs covered with green phosphor, as 1-3W 'ice blue' 480-490nm LEDs. They are not true cyan, a pale skyblue with much lower saturation due to the wideband green emission from the phosphor.
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Re: A new source
Since the discussion of amber and yellow came up, I figured this would be a good place to mention a trick I've discovered to make 590nm (LED or LPS) look like a pure yellow.
Stare at red light, especially at the lightest part (which looks yellowish because it stimulates the green eye cones as well). Eventually, the whole thing looks more and more orange, and long enough, it will itself look almost amber.
Now, look at amber; it looks like a nice lemon yellow (slightly greenish, instead of reddish). Similar to phosphor yellow, but more saturated, like the monochrome amber. At a distance, it's very odd, because it looks not much different from white, yet, again, it's fully saturated. As it gets closer, it looks like a funny "pine oil" golden color, then when it's close, like lemon yellow.
If you look at blue-green, like 505-515 traffic signal LED's, it looks almost like cyan.
(The colors begin slowly normalizing themselves).
Since the discussion of amber and yellow came up, I figured this would be a good place to mention a trick I've discovered to make 590nm (LED or LPS) look like a pure yellow.
Stare at red light, especially at the lightest part (which looks yellowish because it stimulates the green eye cones as well). Eventually, the whole thing looks more and more orange, and long enough, it will itself look almost amber.
Now, look at amber; it looks like a nice lemon yellow (slightly greenish, instead of reddish). Similar to phosphor yellow, but more saturated, like the monochrome amber. At a distance, it's very odd, because it looks not much different from white, yet, again, it's fully saturated. As it gets closer, it looks like a funny "pine oil" golden color, then when it's close, like lemon yellow.
If you look at blue-green, like 505-515 traffic signal LED's, it looks almost like cyan.
(The colors begin slowly normalizing themselves).
JoakimFlorence
Newly Enlightened
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Re: A new source
At exactly 490 nanometers, the color is right on the edge between blue and green. For any other color LED the wavelength could be plus or minus 15 nanometers and it wouldn't matter that much, but at 490 nanometers there is a sudden cut off. Anything below 490 is blue (a sky blue tint) and above 490 the color has is a very greenish-cyan tint. For this reason, I feel that "true cyan" is a very elusive color. To make matters more complicated, LEDs give off a more trailing amount of longer wavelengths from their peak wavelength than they do of shorter wavelengths. It is commonly said that color LEDs only give off a single wavelength, but this is not entirely true. The wavelength emission from an LED is very narrow, but it is not truly a single wavelength value. So even if an LED had a peak wavelength emission of 490 nanometers, chances are the color is going to be more green-tinted than 490 nanometers.
If you want to get an idea of what 490 nanometers actually looks like, look at the faint blue-green terbium spectral line from a fluorescent lamp. Either use a prism or a diffraction grating and hold it up to the light. You can also use an ordinary CD, just stare into the reflection at the right angle. You will notice that even the spectral phosphor line is not entirely a single discrete wavelength (though it is very narrow). On one edge of the line a faint light blue turquoise will seem to predominate, while on the other side it looks more greenish cyan. This spectral line is right on the border between blue and green.
If you ever get the opportunity, look at the 488 nanometer line from an argon laser. It is a sky blue color, with just a little cyan hint, but definitely and distinctively blue.
You can find cyan bin LEDs being sold on ebay, marked as 490 nm, but many people who buy them will be disappointed. They're not truly a real cyan color, not quite. Although I suppose the definition of "real cyan" can be a little subjective. I mean they're definitely not on the bluish-side of cyan. I suspect these LEDs may actually be putting out an emission closer in the territory of 490-495 nm.
To make matters more confusing, 505 nanometer "traffic signal" LEDs are commonly called "cyan" although they certainly aren't. They are, however, more cyan than 520 nm, which is a forest green color. I suppose it's all relative, to some degree.
At exactly 490 nanometers, the color is right on the edge between blue and green. For any other color LED the wavelength could be plus or minus 15 nanometers and it wouldn't matter that much, but at 490 nanometers there is a sudden cut off. Anything below 490 is blue (a sky blue tint) and above 490 the color has is a very greenish-cyan tint. For this reason, I feel that "true cyan" is a very elusive color. To make matters more complicated, LEDs give off a more trailing amount of longer wavelengths from their peak wavelength than they do of shorter wavelengths. It is commonly said that color LEDs only give off a single wavelength, but this is not entirely true. The wavelength emission from an LED is very narrow, but it is not truly a single wavelength value. So even if an LED had a peak wavelength emission of 490 nanometers, chances are the color is going to be more green-tinted than 490 nanometers.
If you want to get an idea of what 490 nanometers actually looks like, look at the faint blue-green terbium spectral line from a fluorescent lamp. Either use a prism or a diffraction grating and hold it up to the light. You can also use an ordinary CD, just stare into the reflection at the right angle. You will notice that even the spectral phosphor line is not entirely a single discrete wavelength (though it is very narrow). On one edge of the line a faint light blue turquoise will seem to predominate, while on the other side it looks more greenish cyan. This spectral line is right on the border between blue and green.
If you ever get the opportunity, look at the 488 nanometer line from an argon laser. It is a sky blue color, with just a little cyan hint, but definitely and distinctively blue.
You can find cyan bin LEDs being sold on ebay, marked as 490 nm, but many people who buy them will be disappointed. They're not truly a real cyan color, not quite. Although I suppose the definition of "real cyan" can be a little subjective. I mean they're definitely not on the bluish-side of cyan. I suspect these LEDs may actually be putting out an emission closer in the territory of 490-495 nm.
To make matters more confusing, 505 nanometer "traffic signal" LEDs are commonly called "cyan" although they certainly aren't. They are, however, more cyan than 520 nm, which is a forest green color. I suppose it's all relative, to some degree.
