Article Contents

Green Topics

Soraa: New LED Technology With Improved Color Quality

Printer-friendly versionSend to friend

Over the past few years, the energy performance of LED lighting has improved, and the costs have dropped, but most LEDs still fall short of their incandescent counterparts in overall light quality. In applications where light quality is truly critical—such as those that use MR16 (for multifaceted reflector 16 cm) lamps for commercial directional lighting—standard LEDs may not be good enough. A new LED technology from Soraa, however, could change that, with MR16 LED replacement lamps that offer the light quality of halogens, efficacies comparable to those of standard LEDs, and a number of other unique benefits.

Almost all mass-produced LED lamps are made by depositing gallium nitride (GaN) onto a sapphire or silicon carbide substrate, but “there is a fundamental mismatch between the deposited layer and the substrate,” according to Clifton Lemon, marketing manager at Soraa. In other words, the inherent dissimilarity in those materials is a weak link that limits their performance, particularly when the LED chip becomes stressed under the high heat conditions in luminaires.

Soraa uses a unique emitter technology that gives its MR16 lamps better color quality and performance than standard LEDs.

By Brent Ehrlich

Soraa_Vivid.jpg

Soraa Vivid MR16 lamps have a color rendering index of 95 and use a single point source of light rather than multiple LEDs; this helps simplify the optics and provides better lighting control.

Photo: Soraa

Over the past few years, the energy performance of LED lighting has improved, and the costs have dropped, but most LEDs still fall short of their incandescent counterparts in overall light quality. In applications where light quality is truly critical—such as those that use MR16 (for multifaceted reflector 16 cm) lamps for commercial directional lighting—standard LEDs may not be good enough. A new LED technology from Soraa, however, could change that, with MR16 LED replacement lamps that offer the light quality of halogens, efficacies comparable to those of standard LEDs, and a number of other unique benefits.

Why is Soraa different?

Almost all mass-produced LED lamps are made by depositing gallium nitride (GaN) onto a sapphire or silicon carbide substrate, but “there is a fundamental mismatch between the deposited layer and the substrate,” according to Clifton Lemon, marketing manager at Soraa. In other words, the inherent dissimilarity in those materials is a weak link that limits their performance, particularly when the LED chip becomes stressed under the high heat conditions in luminaires.

Soraa, on the other hand, uses GaN applied to a GaN substrate, a technology developed by Shuji Nakamura, the same physicist who invented the industry standard blue LED (more on this later). “GaN on GaN allows ten times more light through, so Soraa can get greater power density and create super-bright, super-small LEDs compared to earlier technology,” Lemon contends. And because the two layers are the same material, there are fewer defects, allowing the LEDs to operate at high temperatures. “If you put too much current through most LEDs, they just fail,” claimed Lemon, “but our LEDs can work up to 120°F, so we can work in closed fixtures. No other LEDs can do that.”

Color quality

Unlike standard LEDs, Soraa’s MR16s create a full visible light spectrum (without the IR or UV). This is because a standard LED uses a blue emitter, or “pump.” We commonly see this some of this blue light in car headlights, flashlights, and some exterior lighting. Red and green phosphors are then used to transform some of the blue light to create white light, with the blue portion of the spectrum coming from the emitter. Blue LEDs are efficacious and relatively inexpensive, but they don’t have violet or much cyan (greenish-blue) and cannot provide deep reds.

Soraa uses a violet pump with red, blue, and green phosphors. Most people will not visibly notice a violet light, but according to Lemon the difference is apparent: “We can provide deep reds, which has a huge impact on the quality of light.” The company’s Vivid series has a color rendering index (CRI) of 95, comparable to that of a halogen lamp.

Quartz halogen MR16s are very popular in commercial applications, particularly retail settings, because they provide good color quality. Most MR16 LED lamps, on the other hand, have relatively poor light quality, so while they may work fine for less-demanding applications, they do not make food, people, or retail goods look particularly appealing.

According to Jim Benya of Benya Lighting Design, “There is a lot of violet in nature, and because the short wavelengths of violet [from Soraa LEDs] sneak through, it makes colors really ‘pop.’” And the light from Soraa activates brighteners that are added to many fabrics and commercial goods. In daylight and under incandescent lamps, these brighteners “absorb violet light and re-emit blue light,” according to Lemon, making products that contain them appear whiter, so the contrast between bright colors and whites can make retail clothing, restaurant food, and other interiors stand out. That’s something blue LEDs cannot do.

Small and bright

Soraa can also improve light quality because it uses a single point source of light and only one set of optics. With most standard MR16 LED lamps, “You have to use a lot of point sources,” Benya said, because most LED MR16s contain four or more individual LEDs. “Each one is a little spotlight with a little lens on it, but you no longer have a point source; you have a cluster of point sources.” With multiple sources, it is more difficult to control the beam, and the light from these LEDs hits the same object slightly differently, producing an uneven effect.

Soraa’s LEDs also put out a lot of light in a small area. The company has versions with equivalent light output of up to 65W halogens in its Vivid line, with 75W equivalent products available in its Premium line (80 CRI). The Vivid products are around 41 to 44 lumens per watt (lpw), which is good for a high-CRI MR16 and not far behind standard blue LED versions. (Note that all LEDs lose approximately 2 lpw for every 1-point increase in CRI above 80.)

Lab-tested lumens per watt are not everything when it comes to efficacy, however. Benya asserts that the real-world performance of Soraa is higher than that of even high-efficacy multiple LED MR16s due to better optical efficiency (measure of the amount of light that passes through or is reflected by the optics). “You need optics to take the light from the lens, and you have to put in lenses and reflectors to concentrate the light where you want it.” He posits that a high-CRI MR16 that uses blue LEDs and remote phosphors may have an efficacy of 60 lpw but an optical efficiency of only 20%, so overall you only get 12 lpw in beam efficiency; whereas Soraa is 50 lpw with an optical efficiency of 50%, so you have a total package that is 25 lpw in beam lumens.

What about cost?

Soraa claims its LEDs are comparable in cost to other high-CRI lamps like Xicato, but it is difficult to compare apples to apples since Xicato is a modular system that requires compatible luminaires and electronics, whereas Soraa is a replacement lamp that inserts into a standard 12-volt MR16 socket.

Depending on the system, Soraa LEDs could have an advantage since they contain a built-in driver, so you could potentially replace halogens in inexpensive MR16 track lighting, making the cost of the overall system very competitive. Benya says that in the lifespan of one Soraa lamp (which has a claimed 25,000-hour lifespan), you would burn through six standard halogens; since you would also consume just one-third of the energy, the payback is about two years.

Bulbs and bases

Soraa is currently available in MR16s with a standard 12-volt GU5.3 base or a driverless 120-volt version with a GU10 base. Color temperatures range from a warm 2700K up to a cool 5000K; outputs vary from 400 to 480 lumens; and beam spreads go from 10 to 36 degrees. Some are available with the company’s Snap system, where lenses and filters are attached and removed magnetically so you can customize the shape and color temperature of the beam. This could be helpful for retail stores that change displays but do not want to replace entire luminaires.

Soraa LEDs are not perfect. The amount of violet from current products, for instance, could be too much for some applications, and Soraa only offers MR16s. The GaN-on-GaN technology has only been commercially available since 2012, though, and the second-generation Vivid line, introduced in 2013, has already improved on the technology.

Soraa told EBN that it will be offering a screw-in PAR16 later this year as well as a PAR30 and an AR111, and the company expects the products to improve further and become even more efficacious, even surpassing LEDs that use blue pumps. This combination of light quality and efficacy has been largely missing from the LED industry; perhaps Soraa can help reinforce the importance of light quality before LEDs garner a reputation similar to that of CFLs.

 

Comments (1)

1 Soraa LED Technology posted by Donna J Leban on 10/07/2013 at 12:05 pm

When reviewing new LED technology, its also important to note the weight of the lamp and results of testing in various fixtures. Early LED MR16's were too heavy to be used in many low voltage track systems, and the enclosures often would not fit in existing track heads and trims. While the GU5.3 2-pin base may be equivalent, many MR16 lamps use additional mechanisms to keep the lamp in place. Combined with additional weight, there is a risk that the LED lamp could fall out more easily. A GU10 base, at least, requires a twist turn that will better lock in a heavier lamp. Also, I would like to see testing of the Soraa lamps in the all-to-common 3" halogen trims, where little air circulation around the lamp is possible. Most LED MR16 lamps will not function in these fixtures. Most will not start with the most common 75 watt electronic transformer. Magnetic and remote transformers are only available in much higher cost housings. While I am enthused to see better color quality and performance, these other hurdles will affect the potential for retrofit of halgoen MR16's.

Post new comment

Welcome !
*
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.
  • Glossary terms will be automatically marked with links to their descriptions. If there are certain phrases or sections of text that should be excluded from glossary marking and linking, use the special markup, [no-glossary] ... [/no-glossary]. Additionally, these HTML elements will not be scanned: a, abbr, acronym, code, pre.

More information about formatting options

September 30, 2013