LEDsmagazine.com MAY/JUNE 2017 15
interview | SAPPHIRE ILLUMINEER
On Mar. 1, 2017 in Anaheim, CA, LEDs Magazine announced the winners in the 2017 Sapphire Awards program with a Gala taking place coincident with
the Strategies in Light trade show. The Gala
closed with the announcement of the Sapphire
Illumineer of the Year — Alexander Wilm, a
senior key expert for solid-state lighting (SSL)
at Osram Opto Semiconductors (http://bit.
ly/2mm5dER). We had a chance to talk with
Wilm about the Sapphire Award, and explore
his insight into the advancement of LED technology for general lighting applications. Wilm
also discussed exciting applications in the
automotive and horticultural areas.
LEDs Magazine: Can you tell us what you
were thinking going into the Gala, and perhaps
a little of your feelings after winning?
Alexander Wilm: I was excited, of course!
It’s a great honor just to be nominated as one of
the finalists. The impressive location, the people, the mood, and the glamour. I also appreciated the wonderful opportunity to meet up
with the influencers of the lighting industry.
Being named Illumineer of the Year was a great
honor — one that would not have been possible
without the support and contributions from
the entire team who was responsible for our
achievements. This award belongs to all of us.
LEDs: How did you come to pursue your
work in color consistency, especially targeting general lighting applications? We know
you have worked in many other application
areas. But give us some background on how
the 10° binning program was started and how
it has evolved.
Wilm: When we started our work in general
lighting applications in 2008, the color render-
ing and color consistency were still significant
challenges for the new light source in the gen-
eral lighting market. We did a lot of intensive
studies, especially on color rendering and color
perception, to prove that the new light source
could compete with the established ones.
During these experiments, we realized for the
first time that if two light sources with different spectra in two different boxes are tuned in
to exactly the same color coordinates, there can still be perceived
color differences. When this happened the first time, we checked
the measurement equipment
and then used a different spectrometer, luminance cameras,
and other test subjects, but the
result was always the same: The
color coordinates were identical but the white
After discussing our findings with scientists and experts from universities, we quickly
learned that this is normal and a characteristic of our eyes. But this was only the beginning
as scientific experiments and the necessary
accuracy vary greatly from the standards in
general lighting. This changed with the higher
requirements on light quality and color consistency. From the Full ANSI Box to 5 SDCM
[standard deviation of color matching, also
called MacAdam ellipses] down to 3 SDCM
and even 1 SDCM, the tighter color binning led
to exactly the same experience like we faced
during our initial experiments: Even though
color differences might not be detected by
measurements, in some cases you may see differences when you least expect them.
Then the solution was obvious: Just apply
the latest 10° color space to the LED binning
and measure the color coordinates under conditions that are matching the real observation
conditions. This was far more effective than
the established 2° color space.
LEDs: How widely is the issue with the 2°
space recognized in the SSL industry? We
hear lighting designers discuss color unifor-
mity and consistency at conferences on a reg-
ular basis. But most never mention that there
is perhaps a fundamental problem with the
component binning process.
Wilm: The issue with the 2°
and the 10° color space is still
quite new for the SSL industry. It
may be very well known by uni-
versities, but there is not much
implementation in the lighting
world outside of research. Maybe
a comparison to the discussion
about CRI can be used as a sim-
ilar example. With higher expectations of
light quality, a better understanding of and
the need for new metrics is higher. There have
been several proposals like FCI [feeling of con-
trast index], GAI [gamut area index], and CQS
[color quality scale] in the past to address the
issue, but only since the publication of the
TM- 30-15 are more and more people under-
standing that 1) color rendering is only one
axis of a more dimensional color quality prob-
lem, and 2) an additional axis with the color
gamut helps to describe and understand the
effect of light spectra. Here, a thorough pub-
lication of information is necessary to inform
the SSL industry of changes that may help to
solve some challenges, as many in the industry
are not aware that there are real solutions for
the problem. The 10° binning is facing similar
challenges: The market experiences problems
for which the scientists have already devel-
oped solutions, but we have to inform the
industry and apply it to the general lighting
market in order to solve the problems.
LEDs: What has been the reception to 10°
binning from customers? Are lighting manufacturers deploying products at this point?
Alexander Wilm discusses LED
evolution for SSL applications
MAURY WRIGHT interviews ALEXANDER WILM of Osram Opto Semiconductors about Wilm being named
the LEDs Magazine Sapphire Awards Illumineer of the Year for his work on improving the color
consistency in LEDs for general lighting applications, and work in other exciting SSL areas.