Lighting Spectral Data

Growroom Design
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A bit of a silly illustration but it may be useful to visualize what information a PAR map / PPFD map provides:

PPFD_Laser_Example.jpg1420×774 350 KB

where the total photons output for each fixture is equivalent, how they spread-out differs. Number shown are simply for illustration purposes as number of photons.

The beam angle tells us how it will spread out. Fixture on the left has a large beam angle. Fixture on the right has a small beam angle. With that, we could potentially calculate the irradiation at any point mathematically (the square law, cosine angles, and the geometry of the light source). A map avoids the math and simplifies the effort by quantifying the information (usually by using actual measurements).

PPFD, itself, is the amount of light within a given area. Which could be a small area or a larger area depending on the definition, typically a square meter. There may be many or few measurements within that area that are then averaged together.

Sensors that measure PPFD have optics that filter the wavelengths of interest and are designed to calculate the photons over a square meter even though the sensor itself may be much smaller. This works well for light sources, such as the sun, which are a distance away from the sensor (or something high up in the ceiling). That is, the square meter being measured is evenly illuminated. For situations where the illumination within that “square” is not consistent and varies considerably, multiple measurements can be taken to get an averaged value. Which would be more accurate but less precise for any point within that square meter.

Because of this, we can look at the above illustration and see that the same number of photons are emitted and the same number of photons exist within the same area. However, as we move around within that area the number of photons at any one point may vary considerably.

Here is where the error comes into play, the sensor is small. The manufacturer calculates the PPFD as uMol/m2/s. Which means, they have to somehow account for the square meter in area.

So, if we switch the measurement to PPFD, a correction factor for a square meter would calculate a much larger value for the “laserbeam-5000” fixture than actually exists in reality when directly under the fixture. The illumination is not evenly covering the square meter. The meter “thinks” it is receiving the same number of photons everywhere within that square meter even if it is not. Likewise, if the meter is outside the area being illuminated for the “laserbeam-5000”, but still within the square meter being measured, it would read zero PPFD. Clearly not the case.

Same number of photons in the area. Error in calculating PPFD due to uneven illumination over that area.

So, if you don’t know the beam angle and the height to fixture, you can’t reliably determine PPFD simply using PPF (as measured from a single point). Averaging over the square meter, for instance, would remove that uncertainty for determining PPFD. Which, I think, is what @Baudelaire was getting at.

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That’s it.

And I’ll take it one step farther. As applied technology, a single point PAR reading, even if “averaged” or somehow normalized within a single small area with multiple measurement data points, still tells you very little about the character of the PA photon field within that area. Your “laserbeam-5000” might still deliver an average PAR over a m2 of 800 - an excellent reading if construed to be representative of all points in the light field. But we of course know this is not true. A different light with a single point PAR reading of 700, but with a PAR variance of less than 10% (665-735) across a m2 field, would be a far superior light in virtually any horticultural application.

I’m wrapping up an extensive series of PAR and spectral testing of SolStrips and SolStrip-based lighting systems. In the process I began searching for benchmarks used by the industry, and trying to find comparable testing data from the big manufacturers. What I quickly discovered is that there really isn’t any, even among the industry leaders.

Take Fluence. I consider the company and its founder Nick Klase one of those leaders. Klase’s early embrace of distributed emitter architecture, and his move, bold at the time, to use mid-power full spectrum (“white”) LED diodes as the foundation of Fluence’s light engines, shows me that the company “gets it” when it comes to applied LED horticultural technology.

Here’s what Klase said two years ago on a Fluence AMA on Reddit (before the company’s $40 million buyout by Osram last year):

NickKlase
2 points¡2 years ago
You shouldn’t have a problem with the statement (it is after all, only the truth). You absolutely should have an issue with light manufacturers that don’t publish their specifications. It’s the latter which makes it difficult for people to know how much light to give their plants.

IMO, consumers should force manufacturers to provide PAR charts. There is no easy way around this, as the human eye (and cheap light meters which measure fc/lux) are useless unless everyone used the same spectrum (which they don’t).

You either need a good PAR meter (which as you noted is expensive) or demand that manufacturers provide reliable PAR charts (which is free). Consumers have power. Stop spending money with companies who refuse to provide basic consumer data.

I realize the predicament, which is why we publish all specifications and PAR maps for our systems.

Except they don’t, anymore. They publish a single-point PAR reading. Worse, they measure it at SIX INCHES from the lamp. Anyone with the most rudimentary understanding of the inverse square law of light can see how misleading such a measurement can be.

Fluence is a serious company. They are clearly making a play for the professional horticultural lighting market. Klase, a trained lighting engineer, now heads up their research dept. They have undoubtedly done all manner of testing on their lights, including extensive PAR mapping. So I thought maybe it was just a matter of asking. After all, Klase himself said light buyers should insist on manufacturers publishing PAR map data. So I asked:

To: sales@fluence.science
Feb 11 at 1:05 PM

I’ve searched in vain on your website for PAR maps for your products. Nick Klase your CEO says at conferences that Fluence publishes all its PAR test data. I can only find the spec sheets, which do not include PAR distribution mapping (which I presume Fluence lamps excel at). Can you send me links or PDFs with your PAR maps?

From: support@fluencebioengineering.com
Feb 12 at 2:07 PM

Thank you for writing in and inquiring about Fluence solutions. When Nick claims that we publish our test data, he is referring to the PPF, wattage, PPFD across a footprint, etc. We do not publish PAR maps of individual fixtures as many people then take it upon themselves to create a deployment strategy for their unique layout. Since we tie our success to the success of our customers, we want to ensure that the deployment strategy is to our standards as each project is different. I would love to get you in touch with the correct person to discuss the specifics of your project if you could tell me a little about your project.

So I replied with the Reddit quotes from Klase’s 2017 AMA, where he explicitly states that light buyers should demand PAR maps. Fluence’s sales rep replied as follows:

From: support@fluencebioengineering.com
Feb 13 at 10:18 AM
​
In the time that the AMA was posted and now the decision to not publish individual fixture PAR maps was made… As I stated in my previous, the removal of individual PAR maps is due to the fact that many people were taking those individual maps and trying to create a deployment strategy for their facility on their own. There is much nuance to the design and this is why we take the consultative approach to learn more about your unique needs, discuss the layout of your facility, and relay that information to our design team to provide a custom view. There has also been the recent release of our second generation of fixtures and there is discussion of standard layouts to give a view of our recommendations and what they provide in terms of PPFD.

When I replied that my “deployment strategy” was a 4x4 tent with reflective walls, the discussion ended. Not enough revenue potential to merit any further response from the Fluence sales team it seems.

Don’t get me wrong - I think Fluence is best of breed among LED horti lamp manufacturers. Their lamp architecture should favor high and even distribution of PAR across the light field. I share the thesis behind that architecture with our SolStrip lamps. I want them to prove that distributed emitter architecture is the best way to design a horticultural lamp. But for some reason, they resist. They of course know what their PAR maps reveal, so I can only presume they do not show a performance advantage over their competitors.

My suspicion, having spent about 100 hours mapping our SolSheets and SolStix Racks in a 4x4 tent, is that the architecture and the diodes are really all that matters, cool space ship designs and clever marketing aside.

@Northern_Loki I would love to have you test a SolSheet X for me and the community, and add it to your published results. And I’d really love it if you PAR mapped a Spydrx in a reflective 4x4 space, so we could have a true comparison of the two. You have already done a great service to the OG community with this thread. How about comparing the flagship product of the industry’s acknowledged LED technology leader with a homemade DIY lamp using the same technology that sells for less than half the price? Hint: at six inches, a center-point measurement of the SolSheet X exceeds the published PAR of the Fluence lamp, measured with an Apogee SQ-520.

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There is a lot to consider in there. I don’t “really” want to unpack and dissect the marketing from the data. At least, not here.

Would you have some of the spectral / PPF / PPFD measurement data you’d like to share with us?

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Are you guys reading the same stuff as me - seems like a disconnect here. Fluence’s PPF numbers in the specs come from an integrated sphere and specify the total amount of light coming from the fixture. It’s not a measurement from a single point - are we talking about the same thing here?

PPF

PPF is photosynthetic photon flux. PPF measures the total amount of PAR that is produced by a lighting system each second. This measurement is taken using a specialized instrument called an integrating sphere that captures and measures essentially all photons emitted by a lighting system. The unit used to express PPF is micromoles per second (μmol/s). This is probably the second most important way of measuring a horticulture lighting system, but, for whatever reason, most lighting companies don’t list this metric. It is important to note that PPF does not tell you how much of the measured light actually lands on the plants, but is an important metric if you want to calculate how efficient a lighting system is at creating PAR.

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That’s true for Fluence and a few other manufacturers, but far from all. I had originally asked how @Northern_Loki was calculating PAR in his tests, absent a sphere. He said he was using a single point measurement.

Nonetheless, an integrating sphere still doesn’t tell you about the quality of the light field, the evenness of the distribution of photons across the “grow zone”. It’s a “total horsepower” number, hence my calling it a bragger’s metric. I don’t care how big the total PPF of a light is, what I care about is that it deliver a consistent 800-900 PFFD across every square foot of my grow space.

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still reading up on this - I found the place where Fluence specs give you the “one point” PPFD reading - I can see how a map would be better…I guess they’re assuming you’ll get the same PPFD evenly across the entire canopy - this basically says set the light at the PPFD strength you want and don’t worry about coverage:

Fluence Bioengineering_High PPFD Cultivation Guide_v1.2.pdf (1.4 MB)

F.jpeg1074×458 153 KB

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Take a look at this nice description by Dr. Bruce Bugee on measuring PAR, accuracy, and the the basis of the terminology:

Mapping PPFD or PAR would be the next level of abstraction. All of these type of measurements are valid and useful.

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That’s exactly the chart that got me scratching my head about Fluence to begin with. As averages of an unstated number of measurements across the areas they footnote, they are basically unimpressive in terms of cannabis requirements. 467 PPFD at 6" (a ridiculous height) for a Spydrx? 207 for a RazrX? Those are lettuce lights.

Only the Plus line of the VyprX has meaningful numbers that get into the optimum cannabis bloom intensity range of 700-900 PPFD - and to do so, they have to cut the standard 4x4 ft testing area by 25% to 3x4 ft to get those numbers. That little tweak removes a significant number of peripheral measurements (and raises the intensity of the remaining area if reflective walls are used) that would weigh down the calculated average by far more than the 25% cut in the tested area suggests.

Even then, the different distance measurements of those lamps defy the basic physics of light. How does the VyprX Plus deliver 1003 umols/m2/s at 18", and 935, just 7% less intensity, at more than twice the distance, 48"? They must be using lasers rather than LEDs.

@Northern_Loki I think these average PAR numbers are literally abstract, derived from raw data (the PAR map) to create an abstracted number that is meaningless, because that metric may or may not reflect actual canopy-level intensity in any meaningful way, or in your spotlight example, anywhere at all in the grow space. And yet, the consistent delivery of sufficient but not overly-intense PAR across every inch of the grow space is critical to heathy, optimized growth. Hence the need for PAR maps.

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Wasn’t arguing against the usefulness of par maps. Simply a video that describes PAR and PPF, how it is measured, and how the terms end-up being interchanged at times. I, for one, have to revisit this stuff time-to-time to refresh my memory.

PAR is a term derived from the data with a specific connotation. Sure it is an abstract concept. As is PPFD or PAR maps. I refer to mapping as being more abstract, from a scientific definition, because we are now adding an additional dimension/variable onto PPF (which is the base measurement). No commentary on the usefulness in that statement, FWIW.

All these various types of measurement are valid measurements. Each with various levels of “abstraction”. For any one measurement, taken alone, such usefulness has limits. That includes PPF, PPFD, PAR maps, spectra, etc.

For instance, derive me the efficiency numbers on a fixture using the PAR map. Could you do it? With some extended effort, possibly. Would it be accurate, not a chance. Now derive it from total PPF. Much more straight forward and much more accurate. There is usefulness in having such measurements. Now, whether that energy is actually going to right place is where the mapping come into play.

Those are designed specifically for close proximity. The manufacturer doesn’t say to use these at 48 inches. Their quote, “SPYDRx PLUS is designed for close-proximity, controlled environment agriculture, and multi-tier vertical farming environments.” Same with the Razr. Spec sheet details 6+ inches. The charts, presented earlier, details PPFD when measured at their recommend heights (minimums). The VyprX, conversely, is specified at 18 inches recommend height (minimum) and is not considered “close proximity”.

Now, are they being misleading/unfair in the presented data? I don’t really know. At least, until we or someone else is able to accurately perform the measurements.

The Spydr has been around for awhile now, someone must have measurements on those by now. Someone?

Edit, found this on another forum (Autoflower.net) from the user Entheogenerator for the XPlus. Don’t know if that person mapped this or if it was copied from somewhere else:

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[1]

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I’ve seen that SpydrX map also. It’s the only map of a Fluence lamp I’ve been able to locate. The numbers seem higher generally than the company’s average PPFD for those heights that you referenced earlier, but they are in line with what I would expect from the type of diodes and wattage of the SpydrX Plus. Which is to say, good intensity and excellent distribution across the light field. And which begs the question, if they are that good, why don’t they publish their PAR maps?

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I’ve found a couple of references to the last generation of fixtures, which I’ve attached.

They way they’ve reported the PPFD in a couple of limited examples is slightly different than what we’d typically see. Instead they’ve opt’ed to provide what amounts to a “heat map”. Heat doesn’t literally mean heat, it denotes an intensity type of graph.

image.png673×886 148 KB

We can note that the mapping they’ve performed for this fixture is based on having no reflective walls. With multiple fixtures in use. Each fixture targets a 4x4’ area within a much larger area. There will be some energy bleeding across successive units and energy bleeding off the edges into the open area. Semi-useful for the small operator.
The user generated map, conversely, is a single unit and does not appear to state the test environment but clearly has something reflecting some of the energy along at least one of the edges. More useful for the small operator.

Here is their VyprX Plus PPFD map:

image.png672×748 144 KB

We can also note that this is a large(r) facility with multiple units over a defined area. Not terribly useful for evaluating a single unit and miles of difference of how I’d deployed such a fixture. They have two units per 16 ft^2 in one case and two units per ~26 ft^2 in the second case each at different heights.

Why they don’t provide the PPFD maps in general (on a single unit) is subject to conjecture. I’d presume it’s partially because they are avoiding publishing data that could be used in a different context under differing environmental circumstances. They know that we’ll be measuring, hacking, and tweaking on these fixtures and then discussing it. Depending on the situation, the measurements may not precisely match what they’ve published. And, under some circumstances, I can see an abundance of discussion accusing the manufacturer of lying on their specs. And, as you know, we spread this information to each other usually for altruistic reasons.

We should be aware of this and instead understand that there are many variables involved. Doesn’t matter the manufacturer. Measurements that we or others make are subject to the effect of such variables along with the competency of our ability to measure them. We have our limitations.

Because of this, I feel that we should take measurements as being indicative of the performance. Data that generally confirms within reason what a manufacturer has published is probably a good indicator that they have also been reasonable. Data that shows clear and significant differences, that upon reflection cannot be attributed to environment, is missing essential test condition information, or user error, should be explored further and then, if confirmed, called into question with vigor.

Here is example of of what I assume they (Fluence) provide to the big players (apparently that’s not us):

image.png1299×734 337 KB

I also think they should/could be providing such information to the smaller / individual operation. When you add all of us together, “we” are probably a significant portion of their revenue. But alas, we don’t know the “reasons” and naturally we assume they are looking to hide something when they are not forthcoming with such useful information. We are left to interpret what information they do provide.

Found this example as well while looking around, example of uniformity differences between two fixtures, both spec’ed to produce 1000PFD according to the author (from [1]):

image.png524×504 74.6 KB
image.png523×504 70.4 KB

Something as simple as that could be useful.

Attachments:
SPYDRx-PLUS_PPFD-ROOM-MAP-1711.pdf (252.5 KB)
VYPRx-PLUS_PPFD-ROOM-MAP-lo.pdf (170.0 KB)

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more grist for the mill - changing subjects back to spectral data - Valoya, a commercial lighting company in Finland, came out with a cannabis-specific spectrum last fall. They say they tested 60 different spectra and settled on this one - it has more colored diodes but it’s basically the same as Fluence Greenhouse - 25% blue, 35% green, 40% red - with a touch of 1% UV:

vcnna.jpeg997×217 23.7 KB

This is also close to natural sunlight - 4600K and a CRI of 95, indicating a close match to sunlight. Their Cannabis spectrum has more blue than the other 4 they offer for horticulture - most interesting! they also say 1% UV helps reduce PM…

vreg.jpeg924×385 65.9 KB

Is a consensus emerging that cannabis needs more blue than other crops? Illumitex and Lumigrow are both starting to offer this type of spectrum after selling red-dominant fixtures for years. My experiment has ended with P.L. Light - their full-spectrum light (30% blue, 30% green, 40% red) worked better for me than their 80% red light. I think red-heavy lights are better in greenhouses and don’t work well as sole-source lights. It may turn out that flowering cannabis prefers a light with a large amount of blue.

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the other examples - Lumigrow:

https://www.lumigrow.com/toplight/

lumi.jpeg881×295 36.4 KB

new Illumitex fixtures:

https://illumitex.com/products/harvestedge/

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It seems the closer you can get to a full spectrum the better. I’m back to using my Solstrip rack comprising of 4 x 2700K, 3 x 3500K and 2 x 5000K. It’s the best performing rig i have ever had. It produced the best yield (going by plant size) yet and some of the most potent buds i have ever smoked.

My 6 x 3500K bar is a very decent all round unit but it’s just not in the same league as a full range rack i’m afraid.
A wide spectrum AND distribution gets the best results :thumbsup:

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sounds like you got a better result with more blue - without blue diodes you’ll need to use 5000K or 6000K white diodes to get close to 24% blue.

There’s been so much talk & hype over the years, and so few actual studies of different spectra on real cannabis plants. Horticulture lighting companies weren’t designing fixtures for sole-source indoor use until cannabis came along - all the other commercial crops use greenhouses & supplemental lighting.

It makes sense that cannabis would prefer a balance of colors similar to the sun - evolution would produce that. And the sun is actually about 4800K. Looks like Valoya took their daylight spectrum - “NS1” and slightly increased blue & red for the canna spectrum. Fluence is selling 4000K (Indoor) and 5000K (Greenhouse) lights w/ a boost to red. The notion that cannabis-bloom lights must look reddish or “warm” may be about to die!

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Spectral balance (and the corresponding results) is an interesting topic.

One key characteristic in many of the studies I’ve looked at are the parameters that they are using as benchmarks. The “what are we looking for” question.

Many of the studies that I’ve seen so far tend towards parameters such as dry mass, elongation, etc. Or, for specialty studies such as UV, they might focus on the quality of “fruit” or anthrocyanin quantity, etc. Perhaps one parameter is to the detriment of another (that is not being measured). E.g. terpenes,etc. And, most papers only focus on a subset of the parameters while keeping all of the other possible variables constant. In fact, you’ve pointed that out with the McCree action spectra (the test consisted of only low intensity irradiation), for instance.

Rightfully so, really. Otherwise the studies would never end. The piecing of those snippets together, applying it towards specific genus, and finding that balance is fascinating. Who knows, maybe the perfect balance between all of the possible parameters truly is broadband. As evolution intended.

Sunlight (as measured in OP):

400-500nm Blue : 25.49%
500-600nm Green : 35.45%
600-700nm Red : 39.05%

– or expanded –

287-320nm UVB : 0.06%
320-399nm UVA : 3.06%
400-475nm Violet-Blue : 11.54%
476-550nm Cyan-Green : 16.07%
551-700nm Green-Yellow-Red : 37.17%
701-850nm Far Red-NearIR : 32.09%

Quite similar ratios to the valoya spectra.

Though, the point of many exercises and industry studies is to seek out and encourage specific desirable characteristics while reducing the undesirable characteristics. The shift between blue and red ratios being one mechanism to manipulate the plant morphology, etc. Toying with these things are interesting particularly for a lightly studied high DLI plant.

When I have a chance, I’ll upload some of the studies that I’ve seen in the past from googling around. They are informative and most relate back plant physiology in one way or another, as understood.

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As a grower, I’ve always used more blue in my bloom room than most, because I liked the quality of the weed that resulted. Even back in the bad old days of HPS I’d throw in a 400w metal halide for last half of bloom to harden up the buds and spike the THC-V. At least that’s what was surmised at the time, the deep blue and UV spectrum induced THC-V production that was critical to the soaring, clear “sativa high” we were chasing.

With LED, we can bring a lot of blue to the table because LEDs are naturally high-blue in spectrum. A simple uncoated LED is around 6500K - those icy white christmas lights we all hate. We use phosphor coatings to convert the super-blue to lower CCT spectral blends. That naturally makes higher CCT diodes more efficient, because there’s less loss from the phosphor coatings that saturate the output of 2700-3500K diodes. So part of what growers see (and what LED manufacturers like Fluence are starting to key in on) is that more blue equals more efficiency equals more raw PAR per watt.

Mo’ PAR equals mo’ bud, with mo’ THC, at the end of the day. Until you are hitting above 1000 PPFD at every point across your canopy, more PAR, where ever you find it, should be the goal. Our SolStrip 5000K strips have the highest PAR of any of the CCTs we offer, but almost no one buys them for bloom spaces. I think they should, but what do I know.

As for Fluence and PAR maps: I don’t think there’s any grand conspiracy afoot, I just think that Fluence’s lamp may be a bit underpowered for what they are, and that as a young startup that just got swallowed by a billion-dollar global corp, they are making the logical business decision to cater to the commercial market and leave the single-light jockeys in the dust. It was inevitable when they sold for $40 million that their new owners would push the $100K sale over the $1.5K sale. 4x4 PAR maps in reflective spaces don’t apply in a greenhouse/ warehouse environment. Fine, as long as we understand that the reverse is true also - multi-light “heat maps” are irrelevant to one and two lamp spaces as well.

The way I see it, a multi-lamp warehouse fitted with 100 Gavita DEs hung at 6 feet is basically one huge Quantum board - distributed points of light that overlap each other and create an evenly distributed, multi-source light field. At that scale, I don’t see the great advantage of mid-power LED diodes over HID. You can argue efficiency, but the latest DE’s are within 10-20% of the efficiency of premium white LEDs, at a third to half the cost. In an commercial op with a 1 year ROI on equipment that’s a hard sell.

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In the original OG days there were always people preaching all-Metal Halide for flowering. They said the quality of flower was better than any yield increase from HPS and more lumens. Have to think the spectrum that makes the happiest plants will naturally produce the best yield and terpenes.

The rumor mill used to say you’d get leafy buds with MH or too much blue, but when I flowered with MH I didn’t see that. Going to find out soon, I’m starting a 4X4 tent under these 25-30% blue lights.

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I tried HPS and MH for flowering in the past but not at the same time. The MH reduced stretch and produced nice nuggets but it wasted more energy adding unwanted extra heat.

I think you’ll be pleasantly surprised but as someone we know recently pointed out you have to run the room a few degrees hotter with led’s to get leaf temps high enough. I’d also add root temps to that, mine were a bit too low when room temp was at my previous ideal of 24C. I now aim for around 27C (80F) and the plants seem to love it.

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Yessir to that. The spectrum was better with MH but the efficiency was much worse than HPS, and thus the waste heat greater, so for many the trade-off wasn’t worth it. With LEDs, we have the option to incorporate more blue without losing efficiency; in fact, we gain it.

I read the studies and listen to Dr. Bugbee’s lectures and end of the day, I think the answer to the perennial question of what is the best spectrum is, “See the sky? That.”

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