Because they are more aerodynamic .
Need those high speed, low drag photons.
It also depends what hemisphere you are in. Like toilets…
And the conversion from radiant flux to lumens would be the integral of the product radiant flux vs wavelength and a “luminosity function”. Not easily calculated but simple in concept.
again, we do know it is in datasheets
I had the datasheets up for both while typing that, it doesn’t. You can search for it yourself here .
Alpg88. Could you explain the difference between:
- radiant flux and luminous flux
- CSL_M1.TG and CSL_M1.F1 “chemistry”
- XPE2 white and XPE2 green “chemistry”
- Lumens/W vs radiometric efficiency
Thanks
appologies for taking so long to reply, you are looking for radiant flux that is measured in mw. and you are correct that info is not in osram datasheet., nor cree posts that info now, xpe datasheet had it but xpe2 does not.
as far as energy emitted green vs red vs white, i will have to find a data for that someplace else, cuz even xpe datasheet only shows radiant flux for royal blue, far red and photo red,
however one thing is clear even without data. white led is a blue led with phosphorous, so even if blue and green make the same amount of radiant flux, white will always have phosphorous loses, and less energy would be emitted (same concept as led lumens vs otf lumens), we know that green and blue are chemically similar, indium gallium nitride, (thou I’m sure exact composition is different from brand to brand and is a closely guarded secret) my guess colors are different due to different ratio of the elements
radiant flux was used for color leds and measured in watts, it is amount of energy emitted, luminous flux are lumens,
white leds, all of them are really blue leds with phosphorous that turns blue into white. as far as chemistry this article will explain better
http://donklipstein.com/ledc.html
radiomertic is radiant flux. lumens are photometric with reference to eye sensitivity.
I don’t know where to start here… there are so many discrepancies in your logic; at least as you’ve presented them in this thread. My best estimation is that you’ve been learning as you go along, but are reluctant to admit your previous errors.
I asked those questions to highlight key areas where it is clear you have misunderstandings, or at the very least don’t communicate what you mean clearly, and/or don’t understand what others are saying/asking.
This back and forth all started because you adamantly claimed that the human eye color sensitivity has zero bearing on the lux and/or lumen measurement. This is decidedly false since a lux measurement is a product of radiant flux (per area) and the photopic human sensitivity curve (aka luminosity function.) You then doubled down on this when stating that a lux meter is an objective instrument independent of the human eye’s sensitivities, however, as kennybobby represented in post 56 from the manufacturers datasheet, the Extech Lux meter (like others) does in fact mimic the human eye’s sensitivity.
I asked in the second bullet point what the difference was between the Osram white and green emitter ‘chemistry’, and then about the differences of Cree’s colors in the next line. The truth is I don’t have any chemical formulas, but that level of specificity wasn’t what I was getting at. You have the right idea about the differences in Cree colors, as they are all ‘native’ monochromatic chips, and differences lie in the semiconductor’s elemental ratios and it’s dopants. The fact that seems to not be understood here is these Osram green emitters are actually phosphor converted (PC), just like the white. The two Osrams likely share an identical blue ‘pump’, and even a good portion of the phosphor chemistry is the same, it just lacks the amber and red additions.
There are two key points here is that myself and others where trying to illustrate by arguing the previous paragraph’s topic: 1) without radiant flux values for the Osram white and green, we cannot say which is more radiometrically efficient and 2) in the case of the PC green emitters, there is absolutely-no-friggin-way (technical term) that they are more radiometrically efficient that their base blue chip alone. Really, this is all looping back around to support the first argument in that more lumens does not necessarily mean more radiometric efficiency .
Your very last line in your last post is what really throws me for a loop here.
Is this your way of admitting you were wrong?
And for the record, I want to be fair to you. You aren’t wrong in the simplest form in that , assuming the same LESA (light emitting surface area) and optics and focus, more lumens will equal proportionately more lux. You also aren’t wrong that on a lumens/watt basis, green typically is more efficient than any other color. It’s the details underneath that need to be straightened out.
wrong about what? isn’t the above statement correct?
actually i was wrong about osram green leds, i had no idea they used phosphorous as well, i guess i’m not up to speed with latest led development as i thought i was,
The statement isn’t wrong, but it’s exactly why several of us have said that the green exceeds white in both metrics (lumens and lux) that are weighted that way.
That’s probably why you were assuming the green version is simply better at generating light (in mW) as AFAIK for Cree the narrow-spectrum LEDs don’t have a phosphor for both green and blue. Osram is broad spectrum green which is probably due to being phosphor converted (and why measuring in lumens might actually be giving a more realistic idea of actual perceived brightness vs some others).
Yes. It is correct. But it directly contradicts what you’ve claimed adamantly in the past.
For example:
And then…
and once more for good measure…
But before we go…
I think it’d be in good manners to apologize to certain folks here that you’ve insulted now that you realize the relevance of what they were saying and that it was true.
ok, i do apologize if i insulted anyone, however i do not see anyone actually prove me wrong with factual data. so lets get to the bottom of this and put this argument to rest,
i do agree i was wrong about osram led, as in the way they are build, which is different from cree, i had no idea, so my apologies for that too
however the question still remains, so how do we get radiant flux data? we could ask osram, but we may have to wait too long, we could measure it if we had proper equipment, but i do not think we do, i sure do not, so how do we get that data? do we really need to measure, or just compare? would heat emitted by the osram led, represent watts emitted? if so, then we could use a thermometer right in front of the led and see how green and white are different, i have no problem doing such experiment, if it were to tell us anything,
I don’t think you insulted anyone, I know I’m just here to talk about lighting tech and maybe have some info for someone curious about something to find (as I have done with lots of old threads here too) so rattling on about the tiniest details is fun! 
Since we know that human eyes are more sensitive to the spectral composition of the green light version than that of the white light one, the LEDs operate in essentially the same way (with just differences in phosphor formulation), and there is no evidence that the green version is actual more efficient in mW electrical input>mW radiant flux the assumption that it comes down to human eye sensitivity seems pretty reasonable to me. Unfortunately I think only specialized tech could give us the radiant flux info to really know decisively one way or another.
You measure radiant flux with a spectrometer. A handful of members have them, of course some better than others. Djozz already tested this led (1mm^2 version) and compared it to white. He didn’t report radiometric power totals, but did share the spectrum and photometric data. If someone is so determined, the data can be back calculated.
Correction to what I said before in that the base emitter seems to be of ~20nm - 425 vs 445 - shorter wavelength. This could in itself explain the slightly higher Vf.
I’m not going to further chase you down on ‘proving you wrong’ since you adequately did that yourself in the respective areas any of us were contending you in.
do we know how much more our eyes (or measuring equipment) is more sensitive to green vs white? i mean if we adjust instruments to reflect our eye sensitivity, we must know the difference. and it’s value
there maybe another way to see the actual difference without it being tied to our eyes. decades ago i used to print my own photos in a dark room, used to develop my own film, photo paper is sensitive to light, it develops darker or lighter depending on how much light it was exposed to and how long. so if we expose a b\w photo paper to green and white led driven by the same current, over same amount of time, if the dark spots are different. that would give us an idea how those two leds are different, as far as radiant output, wouldn’t it? at least in theory, we only need to see a difference. not actual value.