SCHOTT solutions no. 2/2016 > Focus / Interview

Prof. Dr.-Ing. Tran Quoc Khanh
Photo: SCHOTT/K. Schaefer; Arndt Benedikt; Fotolia

”The future of the LED lies in Smart Lighting”


An interview with lighting expert, Prof. Dr.-Ing. Tran Quoc Khanh


Dr. Haike Frank

Prof. Khanh studied mechanical engineering and earned his doctorate degree in the field of optical spectroscopy. He then worked in the industry for 16 years before he took over the chair of lighting technology at the Technical University in Darmstadt in 2006. Among others, his current projects focus on how light and colors are perceived.

Why is light so important to us ­human beings?
Light has two direct effects on people. A ­visual effect because light and colors are what allow us to perceive our environment. Light also influences our biorhythms and our ability to concentrate and thus directly affects what we can achieve in our lives and our performances at work. Then, there is the indirect effect where we use light to increase yields in agriculture.

What is the perfect light?
Essentially sunlight with the full color spectrum ranging from infrared to ultraviolet. For over 135 years we have been using electric light that was generally not optimal because it was impossible to produce the entire color spectrum. Now only LEDs make this possible, as they can be used flexibly to create any lighting mood.

How have LEDs developed?
Thanks to the work of Nobel Prize winner Professor Shuji Nakamura, white LED light has been around since 1994. Research and industry have been working on increasing the energy efficiency of LEDs for 20 years. Light and color quality have improved quite significantly since 2012. These new LEDs are what make it possible for us to use LEDs for lighting in museums, on factory floors and in airplanes. Most recently, the focus has increasingly been on their service lives and efficiency.

How can LEDs be put to the best possible use?
LEDs are very temperature and current sensitive, and they also age. That means that each LED has variations in light color. Sensors must therefore be used to measure the colors of the LEDs and match them with each other. Since LEDs cover the entire color spectrum, and as semiconductors are very fast, they produce the perfect light and allow for it to be controlled precisely and ­intelligently.

How do you expect LEDs to be used in the future?
When it comes to increasing their efficiency, the optimum is close to being reached. Therefore, LEDs will be increasingly used in Smart Lighting. Here, I am referring to intelligent control of light, from switching it on and off to dimming and even changing its colors with the help of sensors. Light will serve as an important element in concepts for Smart Homes, Smart Offices and Smart Cities.

Please give us an example.
Let’s take the car. With the advent of autonomous driving, the cabin will increasingly become a place for us to engage in personal activities such as working or relaxing. Sensors that measure the environment combined with those that measure our physical and mental conditions will allow for optimal lighting scenes to be programmed to suit the current moods we are in. We will also see a similar development in the office of the ­future. —
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