Lighting Spectral Data

[Northern_Loki]

Yes, not surprising that the spectrum matches. Fluence is one manufacturer that publishes reasonable data and specs. A bit less far red, a bit more white, perhaps more blue but this could just be positioning of the sensor since 18 inches is pretty close for a unit that’s laid out as a long bar. And, this was measured in a functioning greenhouse, so not the best measurement environment.
Perhaps the irradiance numbers would be interesting to look at closer but since the Fluence charts are relative, there’s a bit of work to line things up. Their spec doesn’t explicitly state the measurement distance but they claim elsewhere that it is around the recommend mounting height of 18 inches. Data is reasonable, otherwise. But as noted, this is not really the main point of the OP and don’t want to get dragged down promoting one lamp over another. People can make their own judgement from the graphs…

Looking down at the canopy from this light:

[Northern_Loki]

Some more information regarding YPF (yield photon flux). Two parts here, first a description and second the data that is used as weight factors.

Yield Photon Flux is a metric utilized in horticultural lighting that is based on the PAR/nm and the ability of a plant to utilize the light energy at each wavelength to drive photosynthesis. In essence, it shows how efficiently a plant is able to utilize the light across the spectrum. The generation of this metric is based partially on the original work performed by McCree, et. al.

The following curve is the relative quantum efficiency in plant photosynthesis:

Notice that according to this curve, the red spectra has higher efficiency than the blue. As such, lights with higher amount of red will tend to have higher YPF values.

If we were to capture the spectrum from a light source, in this case sunlight:

And, then overlay the values used to generate PAR (PFD) and YPF, we have the following:

The orange area consists of the values used to generate YPF. These values are the values of the original spectrum multiplied by the relative quantum efficiency (RQE) transfer function.

The dark blue area consists of the values used to generate PAR which is essentially the original spectrum with the ends chunked off.

Notice that YPF extends further into the deep blues and deep reds and that the reds contribute more to the final result.

There are some criticisms regarding YPF. The main criticisms is that the original works used to generate the RQE for plants was that the test used relatively low light levels of less than 200 umols.

For those into numerical analysis, here is the data for RQE where RQE is multiplied by the umols/nm then integrated to produce YPF.

[Muleskinner]

Here are the spectral graphs for P.L. Light Hortiled fixtures. I really like the table of how much light is in red, green, and blue as a percentage, I asked Fluence for the same breakdown and they couldn’t give it.

Spectrum_details_HORTILED_Toplight.pdf (65.3 KB)

Lumigrow also breaks it down into percentages - they have new, passively-cooled bar fixtures coming out soon, should be interesting

https://www.lumigrow.com/documents/download/specsheet-proe-77000003-lumigrow.pdf

btw Fluence did tell me their white diodes are a blend of 6000K and 3500K. Greenhouse spec is an average of 5000K plus the red 660nm diodes, Indoor is an average of 4000K plus the extra red.

[Northern_Loki]

Here is what I had measured for the Vyprx’s CIE:

So, yes, right around 5000K appears to be an accurate statement from Fluence.

I’ll calculate the percentages for the Vyprx if you’d like. Just need a definition on what would be considered the “blue” spectral range vs “green” vs “red”, etc.

[Muleskinner]

cool - you’ve got some fancy toys!! I also have this - the old Fluence spectrum from the BML days. interesting, their old spectrum matches PL LIght, Philips, Lumigrow, Heliospectra, and Illumitex very closely. I’m curious to see if the Physiospec spectrum with the predominately white diodes contines now that Osram owns the company.

I’ve always wondered if they switched to Physiospec Indoor since its orange glow kind of matches HPS - maybe they thought it’d be an easier sell to greenhouse managers? They say their research backs it up but everyone else is using more red-heavy spectrums…

[Muleskinner]

@Northern_Loki

I’ll calculate the percentages for the Vyprx if you’d like. Just need a definition on what would be considered the “blue” spectral range vs “green” vs “red”, etc.

Sure, how about using 400-500, 500-600, 600-700. Or PL Light defines green as 470-620nm.

From what I’ve read the McCree curve is not worth much, especially for what we do with cannabis. I believe it was derived from shining very dim light on tiny pieces of English Ivy in a lab?

I have vegged plants under PL’s Cannablum spectrum which is 80% red, 10% blue, 10% green and the plants stay nice and compact and vigorous, I don’t believe plants need more than 10% green.

[Northern_Loki]

Hmm, interesting.

Yeah, I’m not sure. The rational for the whole blurple thing originally was to target the phytochromes sensitive to those spectra. Then, we learned that green tends to penetrate deeper into the tissue allowing further activation of photosynthesis. And then we started to fill out the spectra with whites to get more of a “pink” spectrum. And, researchers continue to learn more with the possibility of other phytochromes that have not yet been identified or understood.
But, I haven’t come across much about “orange”, which would be a bit more yellow, specifically.

[Muleskinner]

The University of Utah guys also have some good info, including breakdowns on standard LED white bulbs, natural sunlight, HID bulbs, etc

Univ.Utah_Growlight_spectral_characteristics.pdf (1.3 MB)

Univ.UtahFULL.pdf (1.0 MB)

aren’t you in Massachusetts @Northern_Loki - is it a cannabis greenhouse with the Fluence lights or something else? Sounds cool.

[Northern_Loki]

@Muleskinner

how about using 400-500, 500-600, 600-700

Sure, I’ll try to calculate these later today and will report back.

@Muleskinner

From what I’ve read the McCree curve is not worth much, especially for what we do with cannabis. I believe it was derived from shining very dim light on tiny pieces of English Ivy in a lab?

Yes, my understanding was that the intensities were very low relative to what we are dealing with. Don’t know the plant. So, the McCree curve may not be the most accurate description of the real world. But, I do believe it does apply in a general sense. Bruce Bugbee has shown that the effect is remarkably consistent across plant species. We just have the intensity question to wonder about and there might be better information out there today (as there’s been a bunch of research on photo-inhibition and damage caused by high intensity lighting). Must be something somewhere…

[Muleskinner]

Professor Bugbee is teaming up with Fluence to redefine the McCree curve, hopefully in a few years they’ll have dialed in the exact best spectrum for cannabis. Supposedly Osram made the 660nm and 460nm diodes specifically for horticulture

Redefining the McCree Curve at Utah State University

[Northern_Loki]

@Muleskinner

The University of Utah guys also have some good info

Good stuff, will look at this.

@Muleskinner

is it a cannabis greenhouse

No. A privately owned “greenhouse” for a variety of crop. Not large but large enough to run several types of crop sufficient for the family. Then, add in a couple of geeks and we are experimenting and learning

[Muleskinner]

sounds great! I think no one’s done more research since the 70’s because the greenhouse industry uses supplemental lighting, not sole-source. With supplemental the sky is going to dictate the exact spectrum.

I think early LED’s had only blue & red and the plants did poorly. Now we know you have to add green and maybe we’ll find out they need UV too. It looks like that new Spydr fixture has a UV lamp in the center.

[Northern_Loki]

@Muleskinner

With supplemental the sky is going to dictate the exact spectrum.

Interesting that you should say that, was just capturing that spectra throughout the day today. Greenhouse + supplemental. You can see the supplemental early in the day which is then quickly swamped by the natural light…

[Northern_Loki]

Here is what I have so far for the Vyprx Greenhouse spectra for the PAR range of 400-700nm:

I do like the poster paper from the University of Utah you’ve presented, I’ll calculate the ranges they use in that paper as well…

[Muleskinner]

very cool! so those numbers include a bit of sunlight too or is that negligible?

yes, I’m grateful for the published research, I think some of these companies are doing their own research but it’s kept private.

[Hoodini]

@Northern_Loki are you in the states? Id like you sign up for your hands on.classes
I also have some new ultra low voltage solar grow lights im putting together that I would love for you to.test. . . For science

[Northern_Loki]

@Muleskinner

so those numbers include a bit of sunlight too or is that negligible?

Yeah, I had to measure that particular fixture while it was in use (or, I should say I didn’t want to pull the fixture from the ceiling). So, there could be a some external light leaking into the measurement. But, it was later in the day and the measurement optic was 18 inches away from the lamp, so I’d presume that any external light would be near the noise floor and contributing little to the measurement.

[Northern_Loki]

@Hoodini

Id like you sign up for your hands on.classes

What’s that? You are looking for some glasses? Sorry, don’t sell glasses

@Hoodini

I also have some new ultra low voltage solar grow lights im putting together that I would love for you to.test

Sure, it would be my pleasure.

By the way, if anyone wants the raw data for personal use, I have the data in Excel format. Would probably be good to have better eyes than I on the actual formulas, too.

[Hoodini]

@Northern_Loki

Would probably be good to have better eyes than I on the actual formulas, too.

I’ll let you borrow mine as soon as I find those “glasses” and awesome I should have it all built and ready for testing in about a month. . .ill even send you the wall adapter (phone charger) for it so you will be able to operated it without the battery pack

[Northern_Loki]

The numbers for the Vyprx greenhouse using Bugbee’s spectra distributions:

I’ll calculate the other fixtures and place that into the OP, as well.

If anyone has the paper, “A biological spectral weighting function for ozone depletion research with higher plants” Caldwell, 2003, I could try calculating the weighted UV as does Bugbee in their paper. If that’s of use…

p.s. and, even though I’m showing two decimal places, there is most certainly several % points of error in there since measuring photons, even with a spectrometer, is a rather crude exercise in estimation. But, in bulk, it provides good estimates of absolute radiation in general and very good estimates relative.