Umol/Watt - "Impossible" Readings

So far in my brief time back here on RIU I've had several comments on figures I've posted for umol/watt output on the LEDs used in our products.

One thing I have always prided myself on is transparency. So I decided to make a post today, get my integrating sphere out of the cabinet, and give you guys some data as if you were here beside me recording it for yourself. To keep things simple I'll be performing a test using a single blue, red and green LED. These LEDs are randomly chosen from a parts box that is over 5 years old.

I am using a Light Scout light meter on the "Electric" reading setting, even though the "Sunlight" setting gives 15-20% higher umol figures. The power supply is an adjustable DC unit with digital read out so you can see the exact volts and amps for each test.

Prepping the LEDs for Testing:

Setting Up the Integrating Sphere:
The sphere was custom engineered and 3D printed here at our offices. It can be used with a Light Scout or Li-Cor light meter. The LEDs are held in place by pegs so they cannot move during testing. The sensor is held in place via the same method. Testing is performed with the lid closed.

Time To Run Some Tests:
Each test is run for 5 seconds so as to not over-heat the LED. You will see the amperage (0.7 or 700mA) and voltage of each LED being tested.

630nm RED:

525nm GREEN:

470nm BLUE:

So here is the data from today's random test on some really old LEDs I found in a box:

630nm Red: 87umol (54.04umol/watt)
2.3V x 0.7A = 1.61W

525nm Green: 49umol (21.21umol/watt)
3.3V x 0.7A = 2.31W

470nm Blue: 58umol (23.67umol/watt)
3.5V x 0.7A = 2.45W

Now all I've done here is record data and perform some basic math with that data. I'm not sure what about this data makes some say it is impossible, or why some seem to think it defies the laws of physics, but at the end of the day all I do is analyze recorded data and base decisions on those findings. I've also now supplied this data to all members on RIU, which to my knowledge no other LED company has done. Hopefully this data will help some of you figure out the umol/joule argument I keep hearing about that seems to lack any practical application to photosynthesis.

HydroGrowLED said:

So here is the data from today's random test on some really old LEDs I found in a box:

630nm Red: 87umol (54.04umol/watt)
2.3V x 0.7A = 1.61W

525nm Green: 49umol (21.21umol/watt)
3.3V x 0.7A = 2.31W

470nm Blue: 58umol (23.67umol/watt)
3.5V x 0.7A = 2.45W

Now all I've done here is record data and perform some basic math with that data. I'm not sure what about this data makes some say it is impossible, or why some seem to think it defies the laws of physics, but at the end of the day all I do is analyze recorded data and base decisions on those findings. I've also now supplied this data to all members on RIU, which to my knowledge no other LED company has done. Hopefully this data will help some of you figure out the umol/joule argument I keep hearing about that seems to lack any practical application to photosynthesis.

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You made me spill my coffee from laughing so much, too early in the morning for me to see this sort of comedy

WTF? Look be honest anyone can isolate a LED chip in a bowel with a lid project the light to a very small area at a close distance and come up with a number they, I or anyone else wanna see... Selling some smoke and mirrors test wasting peoples time ani't gonna garner much respect..

TEKNIK said:

You made me spill my coffee from laughing so much, too early in the morning for me to see this sort of comedy

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Thank you for showing us all your true colors. You've been one of the most vocal members who stated this data is impossible, and yet rather than providing any sort of evidence or theory in an attempt to disprove this real-life data, you have chosen ignorance and denial. At the end of the day you're only hurting your own reputation here by choosing to ignore science.

I encourage you to create a post that supports any of the comments you've made regarding the impossibility of this test data or your umol/joule argument with real-life testing as I have. It's far too easy to talk crap on a forum, but backing up what you say is something only I seem to be doing here. So if we are keeping score, that's HGL: 1, TEKNIK: 0

HydroGrowLED said:

Thank you for showing us all your true colors. You've been one of the most vocal members who stated this data is impossible, and yet rather than providing any sort of evidence or theory in an attempt to disprove this real-life data, you have chosen ignorance and denial. At the end of the day you're only hurting your own reputation here by choosing to ignore science.

I encourage you to create a post that supports any of the comments you've made regarding the impossibility of this test data or your umol/joule argument with real-life testing as I have. It's far too easy to talk crap on a forum, but backing up what you say is something only I seem to be doing here. So if we are keeping score, that's HGL: 1, TEKNIK: 0

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Are you high as fuck or something?

TEKNIK said:

Are you high as fuck or something?

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Thank you for letting us know you lack the capabilities to perform any testing that refutes this testing or supports your own arguments. Thank you for showing everyone that all you're here to do is be a troll who claims to be correct, but can't back any of it up when called to. I will know better than to respond to or address any of your comments on any of my threads from here on out as a result if your inability to back up your own words or conduct yourself in a professional and scientific manner. Take care Teknik.

HydroGrowLED said:

Thank you for letting us know you lack the capabilities to perform any testing that refutes this testing or supports your own arguments. Thank you for showing everyone that all you're here to do is be a troll who claims to be correct, but can't back any of it up when called to. I will know better than to respond to or address any of your comments on any of my threads from here on out as a result if your inability to back up your own words or conduct yourself in a professional and scientific manner. Take care Teknik.

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I am not trolling you in any way, I am genuinely concerned about your mental health right now.

hahahahhahahahahahhahahhahhahahaha

TEKNIK said:

I am not trolling you in any way, I am genuinely concerned about your mental health right now.

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i was just going to say either you have got more neck than a giraffe or you have some type of brain tumor.

teknik i bet your green with envy over his test equipment?

grotbags said:

teknik i bet your green with envy over his test equipment?

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It seems that hydrogrow has some sort of state of the art insane equipment, I really don't know what to say here so I guess I will not comment further as I have to get some work done today and this thread makes me laugh too much.

That sensor takes a small μmol/s reading and converts it into a larger μmol·s/m2 reading.

That means if you had perfectly even light distribution over (1)m2 the sensors readings are going to stand and be true anywhere in that (1)m2. But.. if you shined a laser in that same (1)m2 and took a measurement with that sensor underneath the laser, that sensor will still say that the corners of the (1)m2 are getting tons of light, and will also say that on average that (1)m2 is producing more μmol than what it really is. So.... If you don't have uniformity the sensor is going to be inaccurate at describing a true quantity of μmol/m2. A sphere is intended to distribute the light uniformly, but they use sensors on the side and not directly in front of it. With your tool taking a small μmol·s/m2 and then multiplying that to produce an average of how many μmol there would then be in 1m2 is messing with your calculation.

The sphere isn't light proof so that's kind of a big deal.

The sensor placement is not correct.

The sensor is averaging a point reading to m2, so without a multiplier you'd at least want your sphere inner surface area to be 1m2.

If you were able to achieve 100% or close to uniform diffusion in the sphere, and either use a multiplier or adjust sphere surface area to 1m2, change sensor location, and block out the light then that sphere would probably give you some data that could be more useful in describing μmol/j than what you're currently capable of.

EDIT:
I don't know what the spectral response curve of that sensor is either..

Maximum theoretical μmol/j effeciencies:
WV ÷ 119.3

440nm = 3.688μmol/j
680nm = 5.699μmol/j

Its not possible to exceed these values due to the laws of thermodynamics.
μmol/j is the same thing as μmol/s ÷ watts

The lightscout meter is garbage.

https://www.rollitup.org/t/lightscout-quantum-par-meters.948811/

The main problem i have with this is that one watt of pure light contains around 3.8 to 6 umols of photons depending on wave length. To say youre light is 54ppf/w would mean either your setup is wrong or somehow youve found a free energy generating epistar lying around at yours that make 10 watts of light out a 1.6w diode.

The issue is DISTANCE and No Standardization among LED Companies for testing. So it would seem the 3m integrated sphere and the photogoniometer should probably both be provided on all horticultural lighting products. Sphere only is kinda acceptable on lamps as the specific reflector used will make a huge impact. In that case the reflector manufacturer should be providing the photogoniometer report by all means.

You have guys like this making umole / watt ratings which I have no idea where he came up with this method. Maybe useful for comparing against his own tests but by no means a "Standard"


This is what most are looking for

ChiefRunningPhist said:

That means if you had perfectly even light distribution over (1)m2 the sensors readings are going to stand and be true anywhere in that (1)m2. But.. if you shined a laser in that same (1)m2 and took a measurement with that sensor underneath the laser, that sensor will still say that the corners of the (1)m2 are getting tons of light, and will also say that on average that (1)m2 is producing more μmol than what it really is. So.... If you don't have uniformity the sensor is going to be inaccurate at describing a true quantity of μmol/m2.

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Before I begin I want to say thank you for providing a detailed and educational response to this thread as you seem to be one of the only members here with sufficient knowledge on the subject to form such a reply. You're helping me to understand where the separation is between your methodology of determining grow light efficiency and the data I use to build lights. I'm beginning to understand now the response to the figures I've posted, as they were never indicative of a meter squared area or taking readings at a meter from the source. They were simply relative data sets for comparison purposes only.


No point-source light distributes light evenly over an area. Light will always have the highest reading at direct center beneath a point-source fixture. Intensity will always lessen as you move away from center. Since we are talking about point-source lights here, even distribution is not a question of If, it's simply not possible. The edges of any point-source fixture will never match the intensity directly beneath the LEDs.

ChiefRunningPhist said:

The sphere isn't light proof so that's kind of a big deal.

The sensor placement is not correct.

The sensor is averaging a point reading to m2, so without a multiplier you'd at least want your sphere inner surface area to be 1m2.

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Light proof or not, zero is zero. The video shows 0 umol before the LED is turned on.

This integrating sphere (8" diameter, 0.13m2) was created specifically for building precise, quantum-balanced spectral ratios to know relative umol output from one wavelength to the next. It is not representative of a 1 meter squared area, nor was it built to calculate a umol/joule/square meter/second reading. Yes the numbers would be drastically different in a 1m2 sphere. At a distance of 1 meter at direct center in an open atmosphere environment, you'd probably get a reading of 1-6 umol from these LEDs (perhaps I'll do this tomorrow for fun). But I do understand now why you and others have stated an "impossible" response to my numbers, and am grateful for you taking the time to better explain how to create umol/joule data (a new concept I've been trying to understand). My data of umol per watt is only applicable to the specific integrating sphere being used and is a measurement without multipliers to compensate for a 1m2 area. Data which was only ever used to calculate spectral ratios.

Just to be certain I'm understanding you correctly (with sensor placement aside) - to get the umol/joule number you're after we would perform this same test in a 1m2 (11.125" radius) integrating sphere. Correct? Now the next question I have is whether you'd like to assist in designing one?

Here you go, just send a fixture to the lab used for these tests and if it comes back with respectable #'s all of the LED fanboys will have no choice but to eat crow

https://chilledgrowlights.com/independent-lab-reports