what type of light..

[Rolling Thunder]

It's unfortunately so true that the market drives the product as much as it does the price (I guess that's an oxymoron of sorts ).

They mention the potential of HID improving spectrum to those levels, but I just don't see how it's possible, at least in any way cost effectively.

You are correct, we stand upon the precipice of great change in indoor lighting.

Hey there BBFan,

I trust your chilling out to some cool tunes and vibes, while indulging in your favorite hobby! LOL :bongin: :watchplant:

As you can likely imagine, I've been rolling around the above words in my head, and thinking about the article's message in general; and it succeeds at giving me great hope, even confidence that LED is the future. Unless HPS can come up with some way to more accurately reproduce the ideal grow spectrum, at all the correct peak points, then it is only a matter of time before LED supersedes HPS, within the public's perception, as the superior form of indoor lighting; for more than just the above stated reason. As the article points out, there are several reasons why LED is the future of indoor grow lighting; the recreation of a more accurate grow light spectrum being the most important of them, however.

A more accurate form of indoor lighting is the key. Are there any recent studies you know of which prove HPS is capable of reproducing a more accurate spectrum and useable form of light? If there are any, I certainly want to read them for myself. So, if anyone out there can hook us up to those published studies, that would be very cool. But assuming that LED does in fact reproduce a more accurate light spectrum, then logically it is only a matter of time before the money or huge investment capital is made available for completing the research.

Literally ten of billions, if not hundreds of billions of dollars are at stake in this game. The company that holds the patent on the first 200 watt diode with a perfect grow light spectrum, UV-B included, will corner the market. The news about the photosynthetically accurate 200 watt LED diode being only about ten years away is the smoke that tells of the raging fire which is not far behind. Someone is going to get burnt and HPS is the most likely victum of the two. HPS is already being given a run for its money by single watt diodes. It will never hold a candle to a photosynthetically accurate 200 watt diode, that's for sure.

In the mean time, even with an incomplete light spectrum, LED is already producing superior crystal covered DANK, than HPS. That was one of the interesting discoveries of the High Times LED-HPS test grows. It was speculated that the stress of an incomplete light spectrum may have caused the increased crystal production under the LED. As the big money begins to flow into advanced LED research and manufacturing, and as the growing public becomes more aware of LED's superior light spectrum, and other selling points, the paradigm shift will occur.

Manufacturing and retail competition drives down cost. That is a fact. Once the growing public gets the picture, in critical mass, then it is only a matter of time before that message gets passed along to the mass manufacturers and retail marketers of garden products and supplies, like indoor growing LEDs. That will surely lead to the reduction of retail cost(s). And I feel rather confident that the big money to be made will attract enough capital investment into the global competition for market control.

RT, A.E.
(Armchair Economist)

 

[leafminer]

HPS is already being given a run for its money by single watt diodes. It will never hold a candle to a photosynthetically accurate 200 watt diode, that's for sure.
- Not according to what I see on this site. I don't rate any of the LED grows I have seen here compared with what could be obtained under HID lamps. And HPS is already pretty much ideal for both veg and flower according to its spectral output. The only remaining issue is heat; HID is a pain for that.

 

[Rolling Thunder]

HPS is already being given a run for its money by single watt diodes. It will never hold a candle to a photosynthetically accurate 200 watt diode, that's for sure.
- Not according to what I see on this site. I don't rate any of the LED grows I have seen here compared with what could be obtained under HID lamps.

Just out of curiosity, leafminer, did you read the High Times article linked above? It reports on two High Times lab test grows they did, comparing a 90w LED against a 400w HPS and a 600w HPS. This is what it says:

"In Trial B, similar systems again pitted the UFO against a 400-watt HPS, only this time the LED side took an extra week to finish. Some concern arose over stretching, as the clone grew to touch the UFO. This resulted in a decision to increase the blue diodes in a second prototype, and it may lead to an increase in wavelength for the red diodes, according to the manufacturer. In the end, the LED side yielded 5% less than the HPS side did.

However, it was reported in Trial B that there were markedly different potencies, with the LED plant producing much more resin. Speculation exists that the shortage of wavelengths aided in this process, as abnormal stresses have been known to increase the production of resin glands. Final calculations taking into consideration the extra week of flowering time on the LED side found that in terms of grams yielded per kilowatt hour (KwH) consumed, the HPS yield was one-fourth that of the LED side.

In Trial C, the grower found similarities to both previous trials. While the LED yielded less than its counterpart, this test pushed the limits of the LED by pitting it against a stronger 600-watt HPS bulb. Resin production on this Cali-O strain was up after just four weeks of flowering, but in the end, the yield was around 20% less. However, the grower did note that the amount of money saved in electric costs compared against the costs of the 600-watt HPS was almost enough to offset the profits lost on yield. An interesting side note in this trial was that the plant on the LED side needed considerably less watering than the plant on the HPS side. It is possible that this is due to lower surface temperatures in the soil medium, or because the plant wasn’t driven as hard and thus drank less."

Check it out: In Trial B, "it was reported ... that there were markedly different potencies, with the LED plant producing much more resin." In Trial C, "Resin production on this Cali-O strain," under the LED, "was up after just four weeks of flowering." In both instances, the crystal production of the LED was superior to that of the two HPS bulbs. In terms of yields, "final calculations taking into consideration the extra week of flowering time on the LED side," in Trial B, "found that in terms of grams yielded per kilowatt hour (KwH) consumed, the HPS yield was one-fourth," or one quarter "that of the LED side." In Trial C, the 90w LED yielded only 20% less dried bud, which is quite remarkable, in my opinion! Now, I call that giving HPS a good run for its money! What do you call it?

Here's a no-brainer (of a question) but I'll ask it anyway: If the 90w UFO faired that well against a 600w HPS, how do you imagine a 600w LED would have performed? Imo, it would have seriously kicked some HPS a$$!!

And HPS is already pretty much ideal for both veg and flower according to its spectral output. The only remaining issue is heat; HID is a pain for that.

Again, here's what the HT article says about the benefits of LED, compared against HID:

"Let’s take a look at the basic advantages of LED lights, moving gradually into the more technical aspects.

"To start with, LED lamps use somewhere around one-fifth the power of normal high-intensity discharge (HID) lighting. One of our recent test products – the UFO LED, manufactured by HID Hut (and depicted on our February 2008 cover) – uses 90 watts while still putting out just as many lumens as a 400-watt MH bulb. Obviously, this amounts to a pretty big savings in power consumption and electricity costs.

"Additionally, LED’s give off a lot less heat than any conventional HID lamp. Gone are the days of air-cooled lighting systems and the necessity for industrial-strength exhaust fans – not to mention showing up on the thermal-imaging screens of narco-copters flying overhead. The latest LED models, such as the UFO, have built-in fans to cool the tiny bulbs, making standard growroom ventilation and air exchanges more than enough to keep room temperatures at optimal levels. Not too shabby.

"So what about the spectrum? Well, here’s where the technology side begins to come into play. It’s worth mentioning that each of these little LED’s can cost the manufacturer upwards of $10 each. When you have 90 LED’s in one lamp, things start to get extremely pricey. The key to keeping this cost down is for the manufacturer to choose LED bulbs that will be more cost-efficient for the consumer. The trick, however, is to not compromise on the best spectral wavelength for your plants. As it stands now, the best LED products in stores (and online) can cost between $550 and $650.

"Still, while $600 may seem pretty high for a single-unit lamp, the argument for it is simple: Savings in energy consumption repays the cost after only a year of use. Manufacturers understand, however, that unless the results are overwhelmingly positive, many indoor growers will remain wary. Even so, when you factor in the costs of ballasts, reflectors, bulbs and cooling equipment for conventional HID lamps, the price gap closes quickly.

"And so spectrum becomes the political name card. Because LED companies can choose diodes based on the color they emit, they can choose the best spectral frequencies for cannabis plants to thrive in. This is a lot harder for HID-bulb manufacturers, although it should be noted that there are ways for them to do so (and this will be covered in Part III of this series). In creating LED products, a compromise is often reached between optimal color wavelengths and cost; this way, the price tag doesn’t become prohibitive, and the plants will grow as well or better than they would under conventional HID lighting.

"The UFO, for example, utilizes two spectral wavelengths; one red and one blue. When the lamp was going though its prototype testing, trials found that with the red diodes at 455 nm and blues at 627 nm, some minor stretching occurred during the flowering stage. To combat this, the company tweaked the lamp, stepping up the number of blue diodes from 10 to 20 out of 90. While the company’s founder acknowledges that he would have preferred to use 660s instead of 627s, the cost of doing so would have made the product five times more expensive, and that just doesn’t work for home or hobbyist growers. It has been these types of adjustments (with more to come) that have helped LED’s become viable options for indoor growrooms.

"Looking toward the future, it may soon be possible for LED lamps to hit every possible color in the spectrum that a plant could want, and to supply it in the exact amounts that cannabis plants need. But right now, LED’s like the UFO have produced yields similar to or better than their HID counterparts in initial trials (see results in final section), and have simultaneously saved growers money on electricity while adding better security and growroom atmosphere than do standard HPS and MH bulbs."

So, on the basis of the above, I am compelled to say that the HPS heat production is not "the only remaining issue." The far greater issue, imo, is spectral output: "Spectrum becomes the political name card. Because LED companies can choose diodes based on the color they emit, they can choose the best spectral frequencies for cannabis plants to thrive in. This is a lot harder for HID-bulb manufacturers, although it should be noted that there are ways for them to do so (and this will be covered in Part III of this series)." And again, "Looking toward the future, it may soon be possible for LED lamps to hit every possible color in the spectrum that a plant could want, and to supply it in the exact amounts that cannabis plants need."

In another place, the HT article states that the only reason LED is not already hitting "every possible color in the spectrum that a plant could want," nor supplying "it in the exact amounts that cannabis plants need," is cost. That will not be the case in 5 to 10 years from now. The cost will definitely come down, but will LED's ever be as cheap as HID lights? Probably not, for economic reasons. LED's practically last forever, compared to HID. If they retailed for the same price as HPS, there would be far more profit in HPS manufacturing, simply from the standpoint of repeat sales, due to the HPS bulbs wearing out much faster. To compensate for that, I expect LEDs will always be more expensive than HID, though not as expensive as they are today. As the higher wattage diodes make greater inroads into the market, I expect that will drive down the price of the single watt diodes, like those currently used in the 90w UFO. - RT

 

[leafminer]

LEDs whatever High Times says, are lower in efficiency.
See hxxp://www.lunaraccents.com/educational-electrical-efficiency-LED-lighting.html
for efficiency of LEDs, varies between 20 - 45 lumens/watt.
See hxxp://www.rileyelectricalsupply.com/pdfs/25.pdf
and you can see that the efficiency of HPS is 85 lumens/watt.
No Contest!
I think I will take independent reviews and science over what HT prints, thanks! And like I said before, if you can find a single LED grow here on MP that clearly demonstrates that LEDs are more effective, tell us. I've been checking some and I never left any comments on the grows because I didn't want to come across as being negative. STRETCH was the operating word I'd say they have in common.

 

[BBFan]

And HPS is already pretty much ideal for both veg and flower according to its spectral output. The only remaining issue is heat; HID is a pain for that.

Based on PAR watts, MH is actually more efficient than HPS by about 5-10%.

IMHO LED will overtake HPS in the not too distant future simply based on the ability to fine tune spectrum. As stated in the article referenced in RT's post, the cost impact is still holding back the availabilty of spot on spectrum for the small time grower. Once those hurdles have been overcome, I think LED will surpass HID by leaps and bounds.

Let's see what Stoneybud can accomplish with his LED grow. He is a well known, respected and experienced grower on this site. For me, that is the true litmus test here (no disrespect meant to any other LED growers here).

 

[leafminer]

Actually as I have said in another thread, light is not the limiting factor to growth, anyway. Root oxygen is. But HPS is actually well-matched to the plant's requirements. There is a strong turquoise line in there as well as all the yellow-orange spectrum that drives photosynthesis. I consistently get 1 to 1.5" of growth per 16-hour day in veg with my relatively small (pair of 150's) HPS and in previous grows I've had dense, tasty bud.
When LEDs come down to the price of HID lamps I'll give them a try. That's for sure. But right now they are too expensive for a ghetto grower like me. I prefer to spend my cash on genetics.

 

[BBFan]

When LEDs come down to the price of HID lamps I'll give them a try. That's for sure. But right now they are too expensive for a ghetto grower like me. I prefer to spend my cash on genetics.

I couldn't agree more Leafminer. Like I said, let's see what Stoneybud can do with his LED grow.

BTW- what methods are you using to get more oxygen to your roots? I grow in soil and use an airstone and pump to aerate my water before giving it to my plants. What other methods can you recommend for soil?

Thanks.

And Thanks RT- another great post.

 

[Rolling Thunder]

LEDs whatever High Times says, are lower in efficiency.
See hxxp://www.lunaraccents.com/educational-electrical-efficiency-LED-lighting.html
for efficiency of LEDs, varies between 20 - 45 lumens/watt.
See hxxp://www.rileyelectricalsupply.com/pdfs/25.pdf
and you can see that the efficiency of HPS is 85 lumens/watt.
No Contest!

Not really! Try dividing that HPS spec by five, since only about 20 percent of those 85 lumens is usable light. LED produces more usable light per lumen than HPS. That is a verifiable fact, as far as I know, but since I don`t know everything, perhaps you can prove me wrong. I am open to that; i.e. being proven wrong, but so far you have been unconvincing. That does not mean I cannot be convinced. Keep trying. Perhaps after I review your linked websites a little closer, I will see the question differently.

I think I will take independent reviews and science over what HT prints, thanks! And like I said before, if you can find a single LED grow here on MP that clearly demonstrates that LEDs are more effective, tell us.

There are a few that prove the point. Why do they have to be ``on MP``? Are other online growing communities somehow less objective and convincing? I see absolutely no rational reason(s) to diss (i.e. discredit) the HT lab test(s), based on assumptions. But if you know of any ``independent reviews and science`` proving your point, that HPS is demonstrably superior to LED, then by all means, let`s see them. I will read them and give you my honest opinion of them.

I've been checking some and I never left any comments on the grows because I didn't want to come across as being negative. STRETCH was the operating word I'd say they have in common.

The "stretch" effect of the LED is quite simple to explain and control. The same laws governing HPS "stretch" equally apply to LED: wattage / lumens per square foot, R/B light wavelength ratios, light angle, canopy distance, humidity, temperature, etc. The point is that the LED `stretch` factor can be controlled in a number of ways, by fine tuning or tweaking the above factors. It is a relative thing and not necessarily the mark of inferiority. If stretch was the sign of an inferior grow light, then that would mean MH is superior to HPS, which we both know is not the case. - RT

 

[Growdude]

I hear alot about LED's and am curious about them but so far the links Ive seen and grows Ive seen so far are a bit unimpressive.

The grams per watt are excellent but the final finsh weights and pure bud size were not.

Perhaps with advanced training and possible duel level growing, like what Stoney is planning will make the difference. But it will take these methods to compare grams per sq/ft with a HPS setup.

 

[Rolling Thunder]

Based on PAR watts, MH is actually more efficient than HPS by about 5-10%.

Great point, BBFan! Thanks. :aok:

Try dividing that HPS spec by five, since only about 20 percent of those 85 lumens is usable light. LED produces more usable light per lumen than HPS.

Though I've seen different figures concerning this, the above PAR rating for HPS is low-balling it some. The actual HPS PAR rating is probably closer to 30 percent; which means only 25 of the 85 lumens per watt is usable light. - RT

 

[Rolling Thunder]

I hear alot about LED's and am curious about them but so far the links Ive seen and grows Ive seen so far are a bit unimpressive.

The grams per watt are excellent but the final finsh weights and pure bud size were not.

Perhaps with advanced training and possible duel level growing, like what Stoney is planning will make the difference. But it will take these methods to compare grams per sq/ft with a HPS setup.

Just curious, Growdude, but have you seen this thread (below) yet? If not, check it out, when you've got some time, and let us know what you think of it.

=> Growing with the 180W Jumbo UFO <= LOCATED @ hXXp://forum.grasscity.com/indoor-grow-journals/464971-growing-180w-jumbo-ufo.html

RT

 

[Growdude]

Just curious, Growdude, but have you seen this thread (below) yet? If not, check it out, when you've got some time, and let us know what you think of it.

=> Growing with the 180W Jumbo UFO <= LOCATED @ hXXp://forum.grasscity.com/indoor-grow-journals/464971-growing-180w-jumbo-ufo.html

RT

10, 180 WATT LED's it better be good, im not a member so I couldnt see any of the pics.
I would like to see the finished product but @ 1800 watts it better be good.

 

[Rolling Thunder]

The actual HPS PAR rating is probably closer to 30 percent; which means only 25 of the 85 lumens per watt is usable light.

Well, I`m not the sharpest knife in the drawer, that`s for sure, as it just dawned on me about 30 minutes ago that 85 lumens per watt is way low for HPS. Why I ought to slap myself silly for that, as I know better! A 600w HPS grow bulb puts out about 150 lm per watt; and the PAR (at 30 percent) would be 45 lm per watt.

10, 180 WATT LED's it better be good, im not a member so I couldnt see any of the pics.
I would like to see the finished product but @ 1800 watts it better be good.

I agree! That Journal is going to be a very, very long one, if the grower sticks to his original plan for it; as those ten 180's will gradually grow to become 50. If I can recall, the operation is set-up for approximately 50w of LED per sq ft. What I`ve seen so far of the grow is certainly looking very good, but not at all what I envisioned 50w of LED per sq ft to be capable of, in the right hands. Not too shabby, though, that`s for sure! - RT

 

[Rolling Thunder]

A 600w HPS grow bulb puts out about 150 lm per watt; and the PAR (at 30 percent) would be 45 lm per watt.

The above statement is, of course, an approximation, or an approximate average. The PAR wattage of HPS bulbs vary from bulb to bulb. Some lower, some higher. Take the 600 watt SUNMASTER Cool Deluxe Grow Lamp, foe example. Here is the description for it posted on a hydro website, randomly selected:

"SUNMASTER Cool Deluxe Grow Lamps emit light from 5000 to 6500 Kelvin, imitating the natural look of daylight. They are an ideal light source for the seedling and vegetative stages of plant growth, while still emitting a wide spectral distribution.

"SUNMASTER Cool Deluxe Lamps surpass many other HID sources in PAR watts - the most objective measurement of total light energy available for photosynthesis.

"SUNMASTER Cool Deluxe Lamps set new standards in general plant lighting, promoting high levels of photosynthesis without compromise."

Watts: 600
Lamp Description: LM.600W.U25.CDX
Ballast Type: HPS
Initial Lumens: 50,000
PAR Watts: 195
Life Hours: 10,000
Operating Position: Universal
( SOURCE: hXXp://www.hydroponics.net/i/131479 )

Note the PAR rating of 195 watts, or 32.5% of the bulb's total wattage. I have see some rated much lower, and others much higher. Please note that this lamp is described as surpassing "many other HID sources in PAR watts;" meaning that there are many other HPS bulbs with a lower PAR rating! On the other hand, if ever you come across an HPS bulb that claims to have a PAR wattage equal to the total wattage of the bulb, don't believe it. That's just false advertizing, plain and simple!

Note as well that the 'A' in PAR is for 'available' and not 'usable' light. The 'usable' light rating is designated as PUR, and does not include 'available' light between 550-620 nm. The PUR watts rating, then, is even lower than the "PAR watts" rating.

My calculation of lumens per PAR watt is a rough approximation as well, as each light band or wavelength differs in the total number of lumens per watt. - RT

 

[Rolling Thunder]

On the other hand, if ever you come across an HPS bulb that claims to have a PAR wattage equal to the total wattage of the bulb, don't believe it. That's just false advertizing, plain and simple!

In the June 2002 High Times article entitled, '4TH ANNUAL STASH AWARDS,' ( posted @ hXXp://hightimes.com/grow/ht_admin/425 ,) we read the following write-up/ review of the Gavita HPS bulbs:

"After years of reliable use in Europe, Gavita HID lamps are now available in the US. Gavita has produced a uniquely shaped bulb with a reflector built into it. One half of the bulb"s inside is specially coated like a mirror. State-of-the-art design produces an incredible 95% rating on usable light. Advantages for the indoor horticulturist are numerous."

Now, perhaps I am reading more into this than the author of it intended, but it reads to me like Kushman is claiming that the PUR watts of a 600w Gavita is 570 watts. Is that what he's claiming? If it is, then don't believe it. I seriously doubt the Gavita HPS is even remotely close to emitting that many PUR watts, let alone a large minority of HPS bulbs!

Note as well that the 'A' in PAR is for 'available' and not 'usable' light. The 'usable' light rating is designated as PUR, and does not include 'available' light between 550-620 nm.

Nor does the PUR watts rating include any light below 400 nm or above 700 nm: "PUR is that fraction of PAR that is absorbed by zooxanthellae photopigments thereby stimulating photosynthesis. As noted above, PUR are those wavelengths falling between 400-550nm and 620-700nm." - RT

 

[Rolling Thunder]

The news about the photosynthetically accurate 200 watt LED diode being only about ten years away is the smoke that tells of the raging fire which is not far behind. Someone is going to get burnt and HPS is the most likely victum of the two. HPS is already being given a run for its money by single watt diodes. It will never hold a candle to a photosynthetically accurate 200 watt diode, that's for sure.

Here is a couple of 4 year old articles on LED R&D, which provide the earlier HT article with some much needed context; and which affords us at the same time a glimpse into how far LED research has come, within just the past few years:-

BRIGHTEST LED ARRAY RECORD
hXXp://led.linear1.org/brightest-led-array-record/

WESTAMPTON, NJ &#8211; February 8, 2005 - Lamina Ceramics today announced it has developed an ultra-high lumen LED white light engine 14 times brighter than any previously demonstrated white light LED array. The 28,000 lumen solid-state device is 5 inches square and is powered by 1,400 watts. It is more than twice as bright as the record-setting RGB (red-green-blue) light engine the company unveiled just a little more than three months ago.

&#8220;Lamina is the established provider of high lumen LED sources, and this development positions us as the only provider of ultra-high lumen LED light engines,&#8221; stated Taylor Adair, president and CEO of Lamina Ceramics. &#8220;Just over three months ago, 10,000 lumen light engines were thought to be impossible to manufacture because of heat build up. Our proprietary technology enabled us to break that barrier. Lamina&#8217;s latest LED light engine is approaching the 30,000 lumen mark.&#8221;

The new light engine &#8211; branded Aterion&#8482; White &#8211; is comprised of 1,120 LEDs with a 5,500°K color-corrected temperature (CCT) and a color rendition index (CRI) of 80. The highly energy efficient array radiates no heat in its light beam and features instant-on, instant re-strike and fully dimmable capabilities.

In October 2004, Lamina&#8217;s Aterion RGB shattered the existing lumen-output record by a factor of 10. Hailed by researchers and lighting designers as a technology breakthrough, the 860 watt Aterion RGB generates a total 13,300 lumens in any of more than 16 million vibrant, saturated colors, including white.

&#8220;Following just on the heels of breaking what many thought was a technology barrier, Lamina has made another significant breakthrough with high lumen output LED sources, noted Robert V. (Bob) Steele, Ph.D., the foremost market researcher in the field of high brightness (HB) LEDs and Director of Optoelectronics at Strategies Unlimited. &#8220;These ultra-bright sources should have a significant impact on development of solid state lighting for many applications, including general illumination.&#8221;

Until the company&#8217;s October unveiling of the Aterion RGB light engine, development of ultra-high lumen LED arrays had been hindered by the inability of the LED packaging to wick away the heat and keep the LEDs cool, causing them to fail.

Lamina Ceramics&#8217; proprietary multi-layer ceramic-on-metal packaging has solved that problem. Designated as low temperature co-fired ceramic-on-metal (LTCC-M), it is a breakthrough technological development providing an unmatched combination of thermal performance and interconnectivity between individual light-emitting diodes, resulting in lower mechanical stress, greatly lengthened LED life and reliability.

&#8220;Because of its new thermal management technology, Lamina is able to densely cluster hundreds of LEDs, resulting in a solid state light source that is many times brighter than anything previously reported,&#8221; explained Professor Ian Ferguson, PhD., School of Electrical and Computer Engineering, Georgia Institute of Technology. &#8220;For solid state lighting to penetrate deeper into the general illumination market &#8211; and if designers are to be fully able to exploit its many unique features &#8211; LED light sources must be brighter and must retrofit into existing fixtures. Lamina is demonstrating that with proper thermal management, extremely bright, cost effective LED light sources can be manufactured.&#8221;

LTCC-M technology emerged from years of research and development in the Sarnoff laboratories, the same labs that developed world-changing inventions such as color television, and key technologies used in cell phones, laptops, watches, today&#8217;s high definition television (HDTV) and satellite TV technology, to name a few.

Lamina, a venture-backed corporation, is the exclusive licensee of Sarnoff&#8217;s 12 years of research into LTCC-M. Lamina has continued Sarnoff&#8217;s spirit of innovation through the ongoing development and optimization of LED arrays.



2. SCIENTISTS DEVELOP NOVEL MULTI-COLOUR LIGHT-EMITTING DIODE:-
hXXp://led.linear1.org/scientists-develop-novel-multi-color-light-emitting-diodes/

LOS ALAMOS, N.M., May 17, 2005 &#8211; A team of University of California scientists at Los Alamos National Laboratory have developed the first completely inorganic, multi-color light-emitting diodes (LEDs) based on colloidal quantum dots encapsulated in a gallium nitride (GaN) semiconductor. The work represents a new &#8220;hybrid&#8221; approach to the development of solid-state lighting. Solid-state lighting offers the advantages of reduced operating expenses, lower energy consumption and more reliable performance.

In research published in the current issue of the scientific journal Nano Letters, the team reports on the first successful demonstration of electroluminescence from an all-inorganic, nanocrystal-based architecture where semiconductor nanocrystals are incorporated into a p-n junction formed from semiconducting GaN injection layers. The new LEDs utilize a novel type of color-selectable nanoemitters, colloidal quantum dots, and makes use of emerging GaN manufacturing technologies.

According to Klimov, who leads the nanocrystal-LED research effort, &#8220;numerous technologies could benefit from energy efficient, color-selectable solid-state lighting sources ranging from automotive and aircraft instrument displays to traffic signals and computer displays. Semiconductor nanocrystals, known also as quantum dots, are attractive nanoscale light emitters that combine size-controlled emission colors and high emission efficiencies with chemical flexibility and excellent photostability. The use of nanocrystals in light-emitting technologies has, however, always been hindered by the difficulty of making direct electrical connections to the nanocrystals. By putting the quantum dots between GaN injection layers, we&#8217;ve gotten around this difficulty.&#8221;

The secret to making the electrical connection to the quantum dots is the use of a technique developed at Los Alamos by Mark Hoffbauer and his team that utilizes a beam of energetic, neutral nitrogen atoms for growing GaN films. The technique, called ENABLE (for Energetic Neutral Atom Beam Lithography/Epitaxy), allows for the low-temperature encapsulation of nanocrystals in semiconducting GaN without adversely affecting their luminescence properties. By encapsulating one nanocrystal layer or two layers of nanocrystals of different sizes, the researchers have demonstrated that their LEDs can emit light of either a single color or two different colors. The two color-operation regime is an important step toward creating devices that produce white light.

The development of the multicolor LEDs is the result of a collaboration between two Laboratory research groups: Klimov&#8217;s quantum-dot team and Hoffbauer&#8217;s team developing advanced nanoscale processing technologies. Laboratory researchers critical to the project&#8217;s success also include Alexander Mueller, Melissa Petruska, Marc Achermann, Donald Werder, and Elshan Akhadov. Daniel Koleske of Sandia National Laboratories provided the GaN substrates used for the LED structures.

The Los Alamos Laboratory-Directed Research and Development (LDRD) program provided funding for the Los Alamos work as an Exploratory Research (ER) project. The research fits into a broader area of expertise that Los Alamos National Laboratory maintains in the field of nanotechnology in general, and quantum dot research in particular. (END OF THE TWO ARTICLES)

So, then, just four short years ago, "Lamina&#8217;s latest LED light engine" was "approaching the 30,000 lumen mark.&#8221; Now they have a 200 watt diode with an output of 200,000 lumens! And high efficiency white light LEDs are now in the market, and being used in some LED grow lights. Viewed from the standpoint of that progress over a mere 4-5 year period, it is not hard for me to envision a high efficiency 200w full spectrum diode being literally just around the corner, in a manner of speaking, precisely as implied by Kushman in his HT article (as linked above)! - RT

 

[Rolling Thunder]

As most experienced growers realize, sooner or later, stretch is partly the result of less than ideal lighting conditions; or inadequte lumen intensity. Lumen intensity, as you all know, is directly related to the beam angle of the light. Sunlight at the equator, for example, has a smaller beam angle and is more intense there than it is in the Northern hemisphere.

Now, it appears that most LED grow lights today are presently built with a standard beam angle of 120 degrees. This is the primary cause of their inability or failure to deeply penetrate the canopy. Reducing that angle to 60 degrees would practically double the lumen intensity, within that light-beam, and greatly enhance penetration of the garden canopy; though that would mean having to cover a smaller grow area, due to a smaller beam angle.

At any rate, here is some more very useful information concerning how to calculate lumens output using the mcd data and LED beam angle:-

Are LEDs inherently directional?
hXXp://led.linear1.org/are-leds-inherently-directional/

No. One way for a manufacturer to boost the luminous intensity spec (usually given in candelas or millicandelas) is to focus the beam more tightly. The same light flux, focused into a tighter beam, will give a higher luminous intensity spec. So indicator LEDs with 10 degree beam width are popular now, in part because they have higher specs compared to the same LED packaged to have a 30 or 70 degree beam width. It&#8217;s more common to see illumination-grade LEDs rated in lumens, which doesn&#8217;t take into account the focusing of the beam.

Arrays built from narrowly focused LEDs will be narrowly focused; arrays built from other beam distributions will exhibit the beam distribution of their component LEDs. Narrow-beam LEDs and arrays can lose apparent impact when viewed slightly off-axis.

How do I convert between candelas and lumens?
hXXp://led.linear1.org/how-do-i-convert-between-candelas-and-lumens/

You can&#8217;t directly convert since they measure different things. The most useful explanation I&#8217;ve found is that lumens measure light output at the source, while candelas measure the light that falls on a surface. As the area of the surface increases, the number of candelas will decrease even as the number of lumens remains constant. Light bulbs and LEDs sold for illumination tend to carry ratings in lumens. Indicator LEDs tend to be rated in candelas.

You can also use this table to get an approximate conversion from candelas to lumens. Find your LED beam width in degrees, and divide the candelas number in your specs by the cd/lm factor listed for that beam angle to get lumens.

beam angle cd/lm
5 167.22
10 41.82
15 18.60
20 10.48
25 6.71
30 4.67
35 3.44
40 2.64
45 2.09


Which measurement shall I use: Candela or Lumens?
hXXp://patmullins.com/ledlightmyths.html

Beware the conversions that simply multiply candela by 12.57 They don't account for angle.

Obtain the Solid Angle of the LED

w = p(Q/2)2
w = p (25)2 (assumes the LED half angle is 25°)
w = p (.43633)2 convert degrees to radians (deg × p ÷ 180)
0.598

Calculate Lumens

f = Iv × w
f = 2.00 × .598 (assumes LED brightness is 2000mcd)
f = 1.196 Lumens

Most signaling or display LEDs are measured in candelas, however, with LEDs showing up in the illumination market, the Lumen is now often required as a unit of measurement for light output.

A simple method for converting from Candela to Lumens is shown to the left. If you know the LED millicandela and its full beam angle, you can use this calculator to quickly convert to lumens.

Candela [Millicandela (mcd)] to Lumen Conversion Wizard
hXXp://led.linear1.org/lumen.wiz

This calculator allows you to do an approximate conversion between millicandelas (or candelas) and lumens for an LED where you know the beam angle. The reason it's approximate is because the specs don't usually include information about how the luminous intensity (in candelas) was measured. This calculator is perhaps most useful in comparing the light output of LEDs with different beam angles.

To briefly explain the math the wizard does, it simply applies the conversion 1 candela = 1 lumen/steradian. To do this, it converts the beam angle you supply into a solid angle in units of steradians.

The likely thing for a manufacturer to do is to list their luminous intensity spec in the most favorable way possible. So it can be the case that this wizard provides inaccurate values--this happens because the assumption in the wizard is that the luminous intensity value you supply represents an average value across the beam angle you supply. It's too tempting for the suppliers to list a maximum value instead, since there is not a standard for measuring this. Beware especially of wide-angle LEDs, which will probably be distorted the most by this calculation. - RT

 

[cadlakmike1]

Hey rolling thunder, I've just got done reading through this thread and i must say that you have posted a lot of interesting reading. LED's have come a long way in recent times. I don't know what the price's are now as compared to the last I looked at them a year ago, but if they have come down(a lot) I'm sure we will see more and more use of them. I'm sure a lot of people will gravitate towards them just because of the lack of heat. I will say this, I have seen a few LED grows in person, and I have never been impressed, but this was a while ago. From what I could see, the potential was there at the tops of the plants, but due to the lack of canopy penetration there was a lot of plant not getting enough light, which ended up being a very inefficient use of the space the grower had. A 600w hps was able to penetrate much better, making it a better use for his space. Like it had been mentioned earlier, altering growing techniques will make a difference. I have been saying for a while that I want to see a very short but wide SCROG grow done unter multiple LED's, I really think that LED's will work well in this situation because the canopy penetration is not an issue.

Anyways, the real reason I popped into this thread, I really think you should start a new thread about LED's and transfer all of this information there to make it easier to find using the search function. I'm not sure if Blancolighter still comes around(i'm not on this site as much as I used to be), he had started a thread titled "The truth about Led's" or something similar to that. I do believe he was advocating Led's. Maybe you could talk to him about adding all of this to his thread(Although I haven't seen his thread in a long time, because there are so many people on this site against LED's, it may have deteriorated and might not be worth pasting all of this in. I really don't know, but it's worth talking to him and checking it out). Tons of useful information here, I'd hate for someone trying to find info on LED's to miss it if they're just searching thread titles and this is titled "What type of light...".

 

[Rolling Thunder]

Anyways, the real reason I popped into this thread, I really think you should start a new thread about LED's and transfer all of this information there to make it easier to find using the search function. I'm not sure if Blancolighter still comes around(i'm not on this site as much as I used to be), he had started a thread titled "The truth about Led's" or something similar to that. I do believe he was advocating Led's. Maybe you could talk to him about adding all of this to his thread(Although I haven't seen his thread in a long time, because there are so many people on this site against LED's, it may have deteriorated and might not be worth pasting all of this in. I really don't know, but it's worth talking to him and checking it out). Tons of useful information here, I'd hate for someone trying to find info on LED's to miss it if they're just searching thread titles and this is titled "What type of light...".

Thanks mike, for the positive feedback. I just checked out Blanco's LED TRUTH thread and it's a three pager with a five-star rating. This one, on the other hand, has'nt even received a single star, so I'm not really sure the members are impressed with it. But I like your idea about transferring the LED material(s) here, in this thread, over to Blanco's, if he's up to. I'll PM him later when I've got some spare time. - RT

 

[Calbear]

I'm using this thread as it seems to be the most recent. I am building 1st garden, on the cheap.Staying w/in the law for now ( total 6 female, plus 12 more veg). Using indoors for veg only, will trans outdoors for flowers, 6 at a time. I have shop light fixtures, 48" t-12, on adjustable chains. Does anyone know if the Virilux Full Spct(6,280K, 94.5 CRI) is as good for veg as the Agrosum tube, with less K and CRI, but, maybe better spectrum? I know I should invest in T-5....maybe next year. And, I can get at least 2 outdoor flower yields this way as it is.
Guess I could shorten all this by just asking: What is the best 4' T-10 or T-12 bulb available?...and, one last question: should I wait for more testing on LED's?...Or, has anyone found one that is better per $$ than T-5??