Math behind

[Greengenes707]

All I want to know is how many photons reach the leaf. WTF do you not understand about that???

Then why did you come into this thread and wrongly say it is incorrect when it is simply your unwillingness to listen and read the info that was presented. Because this thread is 100% right and verified by multiple spectroradiometer, spheres, and goniometer...but because you cry and want something else, you break down into this little baby that can't have his way. For someone that thinks they are so intelligent and nobody has anything to offer, you sure are very misleading and incorrect about your terminology. and if you took the time to actually conform to the scientific labeling of these certain metrics, you might actually get to the info and dialogue you want. Being 'too cool for correctness"...is not helping your case. But you really don't want that....you just want to "show"everyone how cool and smart you are. But is really just turning around on you. Sorry you're in such a bad place with your self that you need to act this way. Hope your days get better.


So if you have something to present that is new and unknown...please feel free to add. Otherwise how about you take some time and learn what you have walked into before you open your premature mouth.

 

[MonkeyPickAss]

Then why did you come into this thread and wrongly say it is incorrect when it is simply your unwillingness to listen and read the info that was presented. Because this thread is 100% right and verified by multiple spectroradiometer, spheres, and goniometer...but because you cry and want something else, you break down into this little baby that can't have his way. For someone that thinks they are so intelligent and nobody has anything to offer, you sure are very misleading and incorrect about your terminology. and if you took the time to actually conform to the scientific labeling of these certain metrics, you might actually get to the info and dialogue you want. Being 'too cool for correctness"...is not helping your case. But you really don't want that....you just want to "show"everyone how cool and smart you are. But is really just turning around on you. Sorry you're in such a bad place with your self that you need to act this way. Hope your days get better.


So if you have something to present that is new and unknown...please feel free to add. Otherwise how about you take some time and learn what you have walked into before you open your premature mouth.

OR he could curse and stomp his feet more while you guys throw facts at him. That seems far more entertaining. I'm shocked you guys didn't tell this dork to fuck off 4 pages ago.

 

[wietefras]

@Greengenes707 Spot on. The "funny" thing is that his own measurements have completely matched up with alesh's calculations:

Guess you meant lux and µmol/s/m^2. Doesn't matter for the conversion, though.
Anyway, I calcuted LER = 209.2 lm/W and QER = 5.23 µmol/J (or 4.59 in the 400-700 nm range). Guess what. (3000 lm / 209.2 lm/W) * 4.59 µmol/J = wait for it = 65.82 µmol/s

What does he do to thank for this clear demonstration of "the math" matching up perfectly with his measurements? He derides alesh for being wrong.

Although alesh was also using the wrong units there, but that's caused by NoFuckingClue using the wrong units to begin with and alesh applied them consistently so it still makes sense.

Either way, QER=209.2 and LER=4.59 and the lumen/lux to PPF/PPFD conversion factor is then 45,57734. Divide 3000lux by 45,57734 and you get a PPFD of 65,82µmol/s/m2.

 

[NoFucks2Give]

lux and PPFD are both irradiance measurements.

Lux is irradiance (lm/m²)
PPFD is radiance measured in µMoles

Just post your SPD data in column B and get the QER and LER results from the sheet. Why on earth must you insist on understanding something which you clearly are not able to understand? What's the point? How does it make everyone else idiots if you cannot understand what it says?

Is it possible I am the only one that can do the math and find the error?
It is you that clearly is not able to understand that I understand.
I posted a very detailed analysis of the spreadsheet calculations. If I am the incompetent idiot you think I am than point out my mistakes.

Listen, I do not expect you or anyone else to understand the math. I do. Not many people on this planet understand how to convert from lumens to µMoles. This spreadsheet is the first time anywhere I have seen someone come this close to doing the conversions. I am very impressed with whoever created this spreadsheet. The formulas are almost impossible to find on the Internet. Why? Because almost no one understands.

So here I am trying to help you guys get it right and all you want to do is blow smoke up my ass.

You will not find anything anywhere as detailed in explaining how to convert radiometric, quantum, and luminous numbers as my post analyzing the spreadsheet.

My formulas, you will not find them anywhere. They are MY formulas, this I created, and I am sharing them on this website.
Like @alesh said my formulas look fishy. That's because no one ever saw them before. He posted that comment while I was working on the spreadsheet post and he did not see where I came up with the coefficient in question. That's okay, if you follow my post I did not remember where I got the 0.00836.

Not sure where did you get the 0.00836 constant you're using. Seems fishy.

@alesh found 0.00836 fishy. But if you take this ugly ass formula in column E =B2/(($H$2*$G$2*$I$2)/(A2*10^-3)) and replace it with this elegant =B2*A2*0.00836 you will see it comes up with same number. .00836 is rounded so there will be a slight difference but negligible.

So if I can replace a formula in the spreadsheet with a number that @alesh finds "fishy" and it works, it is not possible I may know something??

So if you could just get the stick out of your ass maybe you will see what I am trying to do for you.

So I'll have to reconstruct how I came up with 0.00863. I do not remember.

It was a reduction of the conversion between irradiance and quantum flux.

Energy Quantum Flux = Number Photons / Avogadro number

= (E•λ•5.03•1015[1/(m²•s)]) / (6.02•10^17[1/µmol])
= E•λ•0.836•10^-2 [µmol/(m²•s)]
Okay! There it is. It goes back just a little further to the number of photons

The number of photons Np can be calculated by

Np= E/Ep
= E•((λ•10^-9)/h•c)
= E [W/m²]•λ•10^-9[m] / (1.988•10^-25) [J/s•m/s] = E•λ•5.03•10^15 [1/(m²•s)] (with Irradiance E [W/m²])

reciprocal of speed of light 1/1.988 = 5.03 times Avogadro number
5.03 / 6.02 = 0.835548
And that where the 5.03 comes from that gave me the 863 => 0.863 => 0.00863
So 863 is used in the conversion between the number of photons and the energy of photons
So 863 is only used in the conversion of quantum to radiometric or luminous or vice versa

 

[wietefras]

Lux is irradiance (lm/m²)
PPFD is radiance measured in µMoles

No that's where you keep messing up. PPFD is irradiance measured in µmol/s/m2

lux = lumen / m2
PPFD = PPF / m2

=B2*A2*0.00836 you will see it comes up with same number. .00636 is rounded so there will be a slight difference but negligible.

You round 0.00836 to .00636?

Is it starting to dawn on you why you keep getting incorrect results?

I prefer to see the formula rather than some made up constant though. Prevents dumb errors like you just made too.

 

[NoFucks2Give]

The "funny" thing is that his own measurements have completely matched up with alesh's calculations:

Except my 62 µMoles came from an arbitrary height. At any other height it would NOT have measured 62 µMoles.
It is 62 µMole ONLY at 19".

Do you understand? This means @alesh and his 65 point something number is likely wrong.

 

[wietefras]

Except my 62 µMoles came from an arbitrary height. At any other height it would NOT have measured 62 µMoles.
It is 62 µMole ONLY at 19".

Do you understand? This means @alesh and his 65 point something number is likely wrong.

Again, the distance doesn't matter for converting between PPFD and lux.

Divide any of your lux measurements by 45,57734 and it will (sort of) match the PPFD measurement (or multiply the PPFD to get the lux). That's what alesh was trying to explain.

His 65 figure is spot on. That's not by chance, but because his math works.

 

[Enigma]

Knna covered this topic in great detail. He has helped people all over the world understand and purchase the best components available, the only issue was shipping from Spain.

http://boards.cannabis.com/threads/building-led-lights-from-facts-no-theories.164607/

If you can follow his threads there is a treasure trove of information he has provided.

 

[NoFucks2Give]

Is it starting to dawn on you why you keep getting incorrect results?

Yep I can make typos.

 

[Stephenj37826]

I hope these pictures help clear up any confusion. This is from a lighting passport under one of our upcoming products. This should help . This is a 3000k 80cri led.

1010.95 umol and 69165 lux. This is all from a single measurement.

 

[NoFucks2Give]

Because this thread is 100% right and verified by multiple spectroradiometer, spheres, and goniometer

I've asked for this verification information and I got nothing.
I would appreciate it if you would point to where this thread is verified.

why did you come into this thread and wrongly say it is incorrect

I came to this thread saying something appeared incorrect. I do not know if it is correct or if it is not. That is why I am here.

I did not reverse engineer the spreadsheet because I had nothing better to do. I sincerely want to know that it does work.
I have asked very specific questions regarding the formulas used and I get nothing. Well other than a hard time.

So if you would point to where this thread is verified, then I can be on my way.

 

[Rahz]

Except my 62 µMoles came from an arbitrary height. At any other height it would NOT have measured 62 µMoles.
It is 62 µMole ONLY at 19".

Do you understand? This means @alesh and his 65 point something number is likely wrong.

What it means is that there is a height that will yield a correct result (by happenstance), but it's not a constant... and you need to know what the expected result should be to measure it at a particular distance. If you had moved the sensor a bit closer you would have measured 65 but it would still be an intensity measurement and not an absolute value. There is no height for a spot reading on a flat surface that will measure the luminosity of a lamp, nor is a spot reading necessary when the manufacturer has provided LPW figures (from an integrating sphere). An integrating sphere collects most of the light so it doesn't need to be a particular size/height.

There isn't a formula for converting a spot measurement to luminosity because cobs don't provide a 360 degree radiation pattern.

 

[wietefras]

What it means is that there is a height that will yield a correct result (by happenstance), but it's not a constant...

In this case it's a comparison of lux and PPFD. So it's not "by happenstance", but an accurate application of conversion factor.

The original post is:

For the Vero Decor 1750K 97 CRI, 63 lm/W
I measured 3000 lm and 65 µMoles at 700 mA at a distance of 19".
So my conversion factor would be 0.021 (62/3000). 3000 x 0.021 = 62.

Note that he incorrectly claims to have measured lumen and "µMoles" when in fact he measured lux and PPFD (µmol/s/m2). Also his calculation of the conversion factor is completely off due to a huge rounding error. Caused by using a multiplication factor instead of a division factor.

Guess that's why he keeps confusing 62 and 65 though.

Then alesh applied his math and replied:

Guess you meant lux and µmol/s/m^2. Doesn't matter for the conversion, though.
Anyway, I calcuted LER = 209.2 lm/W and QER = 5.23 µmol/J (or 4.59 in the 400-700 nm range). Guess what. (3000 lm / 209.2 lm/W) * 4.59 µmol/J = wait for it = 65.82 µmol/s
...
You're also confusing luminous flux with illuminance, PPF with PPFD.

So even though alesh just keeps the lumen and translated the "µMoles" into PPF, he also states these are incorrect. It doesn't matter anyway. If it was lumen and PPF the calculation would be accurate too. Just as well as now when in fact it's lux vs PPFD.

Either way,
- the measured conversion factor is 3000lx / 65µmol/s/m2 = 46lm/µmol/s
- alesh calculated LER=209.2 lm/W and QER=4.59µmol/J with a resulting conversion factor of 209.2lm/W / 4.59µmol/J = 45,58 lm/µmol/s.

That difference is well within the accuracy margins and could already be caused by rounding issues in the measurement itself.

 

[NoFucks2Give]

hope these pictures help clear up any confusion

Sorry, all I was looking for was the height of your PPFD measurements. It's not there.

The Action Spectra only confuses me more.

The action and absorption curves below came from an authoritative graduate level textbook, Plant Physiology and Development 6th Edition. There is an explanation of it here: http://6e.plantphys.net/topic07.01.html
http://6e.plantphys.net/topic07.01.html
Also McCree on took measurements at 25nm increments, from 350-750. Your plot looks like it has 8 points between 460 and 500. Whereas McCree only had one measurement point (at 475) between 460 and 500. Just an observation.

I believe McCree's Action and Quantum Yield were relative numbers and not absolute. Your plot make it appear as through there is actually substantial action activity taking place between 500 and 650nm. This is not true. The relative numbers are after absorption. Absorption between 500 and 650 is quite low so action is also quite low. Your plot is showing the percentage of action from only of the photons absorbed, not total photons that reached the leaf. The Plant Physiology action curve is absolute. Where no action can take place if photons are not absorbed. Most photons in the green spectra are reflected. That's why, the same as a green piece of paper, a leaf appears green to humans. If a leaf were to receive only wavelengths that are absorbed the leaf will appear black as is the case with red and blue. If the levels of red and blue are adjusted for leaf absorbance the leaf will appear black.

You seem to be avoiding answering about the height of the fixture at the specified PPFD.


Notice the small region where action is above absorbance just before 600. The small gap between absorbance and action around 580-600 is the big ass peak on your plot. Looks deceptive.

 

[NoFucks2Give]

That difference is well within the accuracy margins and could already be caused by rounding issues in the measurement itself.

Okay that looks very good. And now it makes more sense to me what is being done.

I still have one question though. Bridgelux specifies 63 lm/W. How does that relate to 209.2 lm/W?

 

[Stephenj37826]

Sorry, all I was looking for was the height of your PPFD measurements. It's not there.

The Action Spectra only confuses me more.

The action and absorption curves below came from an authoritative graduate level textbook, Plant Physiology and Development 6th Edition. There is an explanation of it here: http://6e.plantphys.net/topic07.01.html
Also McCree on took measurements at 25nm increments, from 350-750. Your plot looks like it has 8 points between 460 and 500. Whereas McCree only had one measurement point (at 475) between 460 and 500. Just an observation.

I believe McCree's Action and Quantum Yield were relative numbers and not absolute. Your plot make it appear as through there is actually substantial action activity taking place between 500 and 650nm. This is not true. The relative numbers are after absorption. Absorption between 500 and 650 is quite low so action is also quite low. Your plot is showing the percentage of action from only of the photons absorbed, not total photons that reached the leaf. The Plant Physiology action curve is absolute. Where no action can take place if photons are not absorbed. Most photons in the green spectra are reflected. That's why, the same as a green piece of paper, a leaf appears green to humans. If a leaf were to receive only wavelengths that are absorbed the leaf will appear black as is the case with red and blue. If the levels of red and blue are adjusted for leaf absorbance the leaf will appear black.

You seem to be avoiding answering about the height of the fixture at the specified PPFD.


Notice the small region where action is above absorbance just before 600. The small gap between absorbance and action around 580-600 is the big ass peak on your plot. Looks deceptive.


View attachment 3959102

The Mcree curve is only for reference. I can put anything behind the spectrum. I only posted the pictures to show you the relationship between PPFD and LUX..... Those should be interchangeable no matter the height. That was a 135 watt fixture at around 12". No matter how far away I measure the PPFD to LUX has a constant ratio.

 

[wietefras]

Okay that looks very good. And now it makes more sense to me what is being done.

I still have one question though. Bridgelux specifies 63 lm/W. How does that relate to 209.2 lm/W?

Good.

The LER is the calculated lm/W which you would get at 100% efficiency for that SPD. We can use this to get the efficiency percentage from the actual lm/W figure. For instance, 63lm/W would only be 63 / 209.2 = 30% efficient.

 

[churchhaze]

209.2lm/W is what the luminous efficacy would be for a 100% efficient light source of that given SPD.

 

[wietefras]

@churchaze, LOL

 

[nfhiggs]

Most photons in the green spectra are reflected

This is a common misconception. Our eyes are strongly biased towards green light - so it only takes a small amount of reflected green photons (versus other colors) to make an object appear green. In vivo leaf studies tell a much different story than simple absorbance charts of chlorophyll dissolved in a solution.
See this paper
spectral reflectivity profile of a high nitrogen marijuana leaf