# Remote Phosphor Tech - Are these efficacy values possiblel?



## slebans (Mar 4, 2013)

For cut sheet remote phosphor panels -in terms of efficacy- I always thought that Intematix lead the field. Today, while browsing I ran across this PR announcement:
http://www.led-professional.com/pro...nces-high-performance-flexible-phosphor-sheet

PhosphorTech's efficacy values are much higher than a comparable Intematix product -in fact the two SKUs I checked have 30% higher efficacy values. I compared the 5000K(70CRI) and the 3000K(80CRI) SKUs.
http://www.intematix.com/uploads/files/chromalit_datasheet.pdf
and
http://www.phosphortech.com/data_sheets/RadiantFlex Online Datasheet.pdf

The RadiantFlex cut sheet only shows roughly 1600 hours of lumen maintenance testing so it is relatively a very new product.

I have no direct experience with these remote phosphor cut sheets/panels. Can anyone answer two questions?
1) Am I comparing apples to apples?

2) Are these higher efficacy values possible under actual operating conditions?

You could achieve very high efficacy values combining these panels with a number of 575mA or 600mA Cree XT-E Royal Blue Leds.

Thanks for any info.


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## jtr1962 (Mar 5, 2013)

It seems the Intematix and PhosphorTech have similar CRI and CCTs, so you are comparing apples to apples. And the higher efficacy values of the PhosphorTech are certainly possible. If anything, I remember being surprised at the low numbers for the Intematix products, thinking they should be 20% or 25% higher. Part of the reason is Intematix makes their remote phosphor products thicker, and it looks like they try to diffuse the light source. This could easily account for the difference. Also, it looks like the PhosphorTech product has a bit less output above 700 nm. This would increase efficiency with virtually no impact on CRI.

If you use royal blue XT-Es as the source, driven at 350 mA with a good heat sink, you could get upwards of 175 lm/W @ 5000K using the PhosphorTech product. At the 550 mA or 600 mA you mentioned, you would probably still be over 150 lm/W.


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## slebans (Mar 5, 2013)

jtr1962 said:


> If you use royal blue XT-Es as the source, driven at 350 mA with a good heat sink, you could get upwards of 175 lm/W @ 5000K using the PhosphorTech product. At the 550 mA or 600 mA you mentioned, you would probably still be over 150 lm/W.



Sorry -I mistakenly typed mA for mW. I was referring to the 575mW or 600mW Royal Blue XT-E Leds, binned at 85C.
Without allowing for losses due to power supply, optical/luminaire, mismatches on Dominant Wavelength Range and phosphor panel thermal issues:

600 mW radiant flux at 1 watt of input power = 60% WPE
1 watt / .6 = 1.66
1.66 input watts = 1 watt optical ouput
At 5217K(74CRI) - lumens per watt of RAD = 300
300 lumens per watt / 1.66 watts = 180 lumens per watt

At 3084K(80CRI) - lumens per watt of RAD = 273
273 lumens per watt / 1.66 watts = 164 lumens per watt

I am very impressed with the possibility of 164 l/w at 3084K(before losses detailed above).


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## jtr1962 (Mar 5, 2013)

Is anyone selling 575 or 600 mW XT-Es? The highest I've seen is 550 mW. Incidentally, if you can keep Tj close to 25°C, then the 600 mW parts would be putting out about 7% more, or about 640 mW. Vf rises slightly, increasing input power a bit, but WPE would go up a few percent, maybe to 63%. That gives ~190 lm/W before the losses you mentioned. You could probably easily get an overall fixture efficiency in excess of 150 m/W if you pick a good power supply plus good optical design. What's nice is thermal management should be fairly easy. The LED heat sink only needs to dissipate about 40% of the input power from the power supply. The rest is dissipated in the phosphor panels, or comes out as light.

Doing the math for a 100 watt replacement (1700 lumens) and 5217K, assuming no need for additional optics, I'm getting 1700/(300*0.6) = 9.44 watts input power to the LEDs. Assuming a 90% efficient 120 VAC to DC converter, you need 10.49 watts from the AC line (162 lm/W overall efficiency). You have 1.04 watts losses in the power supply, and another 3.78 watts of heat to be dissipated from the LEDs. That's only 4.82 watts of waste heat to be dissipated in the base of the bulb. The remote phosphor panels will also dissipate some heat, but probably less than a watt. The same calculations for the 3084K version gives 5.31 watts of waste heat total and overall efficiency of 147 lm/W.


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## slebans (Mar 5, 2013)

jtr1962 said:


> Is anyone selling 575 or 600 mW XT-Es? The highest I've seen is 550 mW.



I checked yesterday before I started this thread - and all of the regular North American suppliers show a listing for the 600mW SKUs:
XTEARY-00-0000-000000Q01
XTeARY-00-0000-000000Q04(better match for PhosphorTech panels)

None of them show the part as in stock - 4-6 weeks to ship. I honestly do not know if the 600mW XT-Es exist in the wild.


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## videoman (Jun 19, 2013)

*Remote Phosphor panels*

Anyone know where I can get remote phosphor panels in 1-3 mm thickness that I can cut to size and experiment with ? like sheets of 1 sq. ft,.
I am looking to use blue leds behind them for 3200K results.


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## slebans (Jun 19, 2013)

*Re: Remote Phosphor panels*

Here is a thread on this subject:
http://www.candlepowerforums.com/vb...phor-Tech-Are-these-efficacy-values-possiblel


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## bshanahan14rulz (Jun 19, 2013)

Sorry for the bump. Just wanted to remind you folks that LEDs aren't the only source of high power output @445-450nm. There are some discrete, hand-picked diodes that put out 2000mW, and have much smaller emitting area than an XT-E, for those who need to keep the lux up. 

Did any of you actually purchase this material?


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## videoman (Jun 19, 2013)

What kind of light output losses, approx. in percentage , can I expect to see by using the remote phosphor.? Say I have 6 blue XT-E's delivering 1000 lumens, how much will that lumen figure drop by the use of the 3000-3200K phosphor ? approx.


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## SemiMan (Jun 20, 2013)

videoman said:


> What kind of light output losses, approx. in percentage , can I expect to see by using the remote phosphor.? Say I have 6 blue XT-E's delivering 1000 lumens, how much will that lumen figure drop by the use of the 3000-3200K phosphor ? approx.




When you are talking about remote phosphor and blue LEDs, lumens is a meaningless term. What you are interested in is milliwatts (or watts) of radiant power. Royal Blue LEDs are not rated in lumens, but in milliwatts.

The remote phosphor specification will include a conversion ratio at a given wavelength.

Semiman


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## foxtrot824 (Jun 20, 2013)

One other very important thing to keep in mind when considering remote phosphor is that they mixing chamber design is very important. A poorly designed chamber will result in very significant losses of output. I can not disclose our designs since I work for a company that produces RP lights but I can say look closely at any tear down of the Philips RP bulbs and you'll see it generally looks like a light funnel from the blue source to the RP.


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## SemiMan (Jun 20, 2013)

The interior must be highly diffuse and highly reflective so that every ray that has a chance to pass through the phosphor does.

Semiman


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## DIWdiver (Jun 20, 2013)

Diffuse AND reflective? Isn't that a contradiction in terms? 

I would have thought that simply reflective would be better than diffuse.


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## videoman (Jun 20, 2013)

Would using 8 XT-E's at their max rated output have the potential to achieve say 2400 lumens, using RP material ? 
I am having difficulty referencing milliwatts of radiant power to actual visible lumens. 
I need a light that outputs in the 2000 to 2500 lumen range. High CRI is what I'm after.


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## bshanahan14rulz (Jun 21, 2013)

DIWdiver said:


> Diffuse AND reflective? Isn't that a contradiction in terms?
> 
> I would have thought that simply reflective would be better than diffuse.



I think it's kind of like the difference between soft white and frosted bulbs. reflective meaning not absorptive, as opposed to specular reflections like mirrors do.

Perhaps the idea is to not have any "hotspots" of pump light hitting the phosphor, since heat can have a negative effect on downconversion in most phosphors. Like, to keep the average irradiance lowest at all points on the phosphor, it would be best to diffuse 100% of the pump light across 100% of the area of the phosphor. This would maximize conversion while keeping heat at the phosphor to a minimum at that output level.

I do have some questions in this regard, though. Are there some phosphors that are more resiliant to heat than others, or is this mainly a function of the material in which it is embedded? And so far, all phosphor uses seem to be having the pump pass through one side, and the usable light coming out the other. What if for my application I wanted to pump the material from the front AND capture and use the light emitted from that same side? It would be a bit bluer than if I had the ability to pump through the entire thickness of the material?


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## Harold_B (Jun 21, 2013)

DIWdiver said:


> Diffuse AND reflective? Isn't that a contradiction in terms?
> 
> I would have thought that simply reflective would be better than diffuse.



Diffuse and reflective is not a contradiction in terms at all. PET is a common material used in mixing chambers and is highly reflective and diffuse. White optics also makes a material and a coating for this purpose. Often people assume that a smooth specular surface is more reflective than a diffuse surface but all that really means is that the reflection is more directional. Sorry to be redundant, I just type slow.....


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## foxtrot824 (Jun 21, 2013)

videoman said:


> Would using 8 XT-E's at their max rated output have the potential to achieve say 2400 lumens, using RP material ?
> I am having difficulty referencing milliwatts of radiant power to actual visible lumens.
> I need a light that outputs in the 2000 to 2500 lumen range. High CRI is what I'm after.



If CRI is your goal there are other solutions that will meet you needs unless you're set on remote phosphor. Besides the many LEDs that have a CRI of >90 Cree makes an LMH2 module that mixes "white" and red LEDs to hit 90+ CRI at about 100LPW.


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## videoman (Jun 21, 2013)

I would really like to experiment with the remote phosphor as it would also act as a diffuser that won't be harsh on the subject's eyes and would eliminate the optics and reflectors altogether. I have a certain design requirement that the phosphor material must be 3/4 inch distance from the XT-E emitter and planing to use 6 leds at 1 amp each. A wide even beam would be also welcome for my application. Figuring I'll get around 1600 lumens from it, if my calculations are correct. My main concern is the placement of the leds as to evenly light the phosphor. An internal reflective material such as chrome spray paint is something I will look into to get all the light on the phosphor. Any thoughts ?


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## RoGuE_StreaK (Jun 22, 2013)

Without being ridiculous, what if you got one of the Philips RP lights and "just" cut in into thirds? If that works, get a couple of them. They're expensive from what I've seen (dunno about USA, but they are ~$80 here), but seems RP sheets are quite expensive anyway, at least you know these ones work as intended and all the hard work's already done?


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## 2xTrinity (Jun 22, 2013)

> _Diffuse AND reflective? Isn't that a contradiction in terms? _


Not at all. Best example I can think of of this technology is integrating spheres, which are used to accurately measure the number of lumens coming from a light source:

http://en.wikipedia.org/wiki/Integrating_sphere

Idea of an integrating sphere is to completely diffuse all the light that is pumped in without a significant amoutn being lost to absorption. The entire surface of the sphere will then be completely uniform and the brightness of light going out the exit port will only depend on the total number of lumens going in, not the beam distribution going in. 


The white coating in remote phosphor bulbs is the same idea.



bshanahan14rulz said:


> I think it's kind of like the difference between soft white and frosted bulbs. reflective meaning not absorptive, as opposed to specular reflections like mirrors do.
> 
> Perhaps the idea is to not have any "hotspots" of pump light hitting the phosphor, since heat can have a negative effect on downconversion in most phosphors. Like, to keep the average irradiance lowest at all points on the phosphor, it would be best to diffuse 100% of the pump light across 100% of the area of the phosphor. This would maximize conversion while keeping heat at the phosphor to a minimum at that output level.
> 
> *I do have some questions in this regard, though. Are there some phosphors that are more resiliant to heat than others, or is this mainly a function of the material in which it is embedded?*


The actual phosphor material itself is a powder suspended in plastic. Tolerance to heat has to do with the material it's encapsulated in. The Intematix produts from what I understand are polycarbonate and are not meant for operating at high temperatures, or high temperature gradients (can cause cracking) The phosphors that are adhered directly to the surfaces of LEDs are embedded in silicone, which is soft and can tolerate high temperatures (150C+) and significant temperature gradients. 



> And so far, all phosphor uses seem to be having the pump pass through one side, and the usable light coming out the other. *What if for my application I wanted to pump the material from the front AND capture and use the light emitted from that same side?* It would be a bit bluer than if I had the ability to pump through the entire thickness of the material?



As a thought experiment lets say you were to shine a blue laser beam, or collimated blue LED beam onto a phopshor panel. A few undesireable things will happen:

1) Unless you AR coat the phosphor plate, you will have a substantial specular reflection. This will be a source of loss. It will also be a source of glare -- an obnoxious (or in the case of a laser, potentially dangerous) blue beam of light will be visible from outside your device

2) A significant amount of the blue light (more than half) will pass through the phosphor unabsorbed. 

3) the yellow light emitted by the phosphor will be emitted approximately equally forwards and backwards. Without some kind of reflector behind the panel, half the light emitted by the phosphor will go out the back. 



To fix 2 and 3 you could try to put a reflector behind the phosphor. A mirror-like surface is not good though because even on a double pass, you'd get a significant amount of blue light that would pass through and not be absorbed (adding to the obnoxious glare problem). The ratio of blue light absorbed to yellow light emitted would also be totally out of whack unless you basically engineered your own phosphor panel from scratch with the intention of using it in a front-lit, rather than back-lit application. 


In the case of back-lighting with a sealed mixing chamber, surface reflection is not a problem -- light that is reflected from the panel, or emitted backwards from the panel will get dumped back into the mixing chamber and will bounce off the walls multiple times being recycled over and over again until the light eventually makes it out. If you were to run a raytrace simulation, many of the rays that eventually make it out of the lamp undergo several "round trips" through the mixing chamber and phosphor before eventually getting out. 

The thickness and absorption properties of the intematix panel is designed with these "round trips" in mind.

Because light often undergoes many many reflections inside the mixing chamber, it's important that the material be highly reflective. The magnesium oxide white coating in integrating sphere and remote phosphor lamps absorbs a fraction of 1% of the light on each reflection. Aluminum or chrome paint (as suggested in this thread) absorbs somewhere on the order of 10%+ percent which adds up to a huge amount of loss. Hobby applications for remote phosphor is not very easy unfortunately.


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