Michael Royer, Lighting Engineer, Pacific Northwest National Laboratory: The CALiPER program looks at typical LED lamp performance attributes. As we've gone through the progression of reports, we've really seen that a lot of times we're coming to the same conclusions-- that based on basic performance, LED products, at least some of them in every category we look at, can beat the incumbent technologies. So we've decided that we need to start expanding what we're looking at, and look at things like beam quality, color quality, shadow quality, flicker and dimming, all these other performance attributes that might not be as easily quantified in a photometric report.

PAR 38s are a directional light source. They're used usually in commercial applications, sometimes in residential applications, typically for display lighting. So you'll see them in a supermarket, in a clothing store. And they're really providing the accent lighting for objects in those spaces.

We have 26 different PAR38 lamps set up, including some halogen benchmark lamps. And what we're trying to do is show the beam quality, the shadow quality, and the color quality, three distinct attributes, using different props to display each of those. When we had evaluation events, we brought people out and asked them to rate and rank each of the lamps based on those performance attributes.

There was certainly variability in the LED lamps. We found in each group, though, that there were some LED lamps that were ranked higher than the halogen benchmarks. And one of the other interesting findings was that generally for beam quality we found that single emitter lamps, lamps that have a central, single point of emission rather than multiple emitters, were generally ranked higher.

This is a single emitter LED lamp, and it was rated the highest for shadow quality and beam quality in this group. So we can see a nice, crisp shadow around the flower pattern on the wall. This is a single emitter LED lamp. You can see a nice consistent color pattern on the wall, also a nice, gradual, but sort of defined fall off of the beam as it extends out away from the center. And the observers found that pleasing.

This is a multiple emitter LED that we actually did the beam quality and shadow quality on. For this sample we can see it's an LED with multiple emitters. And so you can see around the edge of the flower shadow, it's sort of a grainy, multiple shadow effect. So it's not really a crisp, clean shadow that's coming from this product.

This is an example of what some of the observers found objectionable-- the stray light outside the beam. So we can see here the main beam pattern for this lamp. If you look up above in that projection, you can see almost a halo or a ring around the center of the beam. It almost has a little bit of a rainbow effect to it. And you might not see that if it were in a real installation. But if it's an option to eliminate this in products, the beam quality would generally be viewed more favorably.

For the color quality evaluation we had two 2,700 K LED lamps, we had three 3,000 K LED lamps, and one halogen benchmark. In each of the 2,700 K and 3,000 K groups, we had low and high CRIs. And in the addition for the 3,000 K group, we also had one in the middle. So for the 2,700 K group, we had an 82 CRI, and a 93 CRI. For the 3,000 K group we had 83, 86, and 92. And we asked observers to generally compare the color quality of these lamps, using the color sample boards that were presented.

Now this is not typical of the way you would compare CRI, which would typically stay within one color temperature group. However, we felt that comparing both provided a more realistic situation that a specifier or a lighting designer would face, of having multiple variables in play at one time. So we have additional reports on PAR38 lamps, dimming and flicker, stress testing, and long term performance.