A short bio

I came to Jena in 1986 at age 21 to study physics because it was the place where you could specialize in astronomy. A few months later, I landed a job as an undergraduate assistant and was introduced to an optical lab to help a PhD student to shoot an Ar laser beam to a photorefractive crystal. To make a long story short : I stayed until my postdoc years. In Friedrich-Schiller- Universität Jena, we were introduced to physics by professors like Max Schubert and Ernst Schmutzer , and did some steps into optics with the help of Falk Lederer (though almost exclusively fiber optics) and Christian Hofmann (sent from Carl Zeiss Jena to teach technical optics). I finished my Diploma in 1991 and PhD in 1995, both in the field of photorefractive crystals, and under the guidance of Richard Kowarschik and Lutz Wenke. Looking back, it was a wonderful topic for graduate studies wich never made it into any product. I had some nice solutions that were looking for a problem to solve. But I learned some essential skills, not only in the lab. 1998 I felt I needed a change and arranged to get a call from Call Zeiss. After German reunification and some horrible years, Zeiss had finally made it into one company, saw better times on the horizon and began to hire young people. My department was making some of the very first optical engines for conference room projectors. Everything was different : Whereas in university, optics was to screw some lens holders on an optical table and look how the laser beam got deflected. Now, you would design some optics with a special software, put some barrel or the like around it, produce drawings, have them released and get the result in a Kanban box a few weeks later. There were increadible people: some could look at a projected image and tell me which element of the lens was decentered (by the way, this was a topic for AI in optics). The late 90s were an exciting time where the projector business grew faster than the knowledge of illumination optics. In these years, the term „etendue“ became finally widespread. Only much later I learned that the fundamentals had been known in various places for a long time, but there was no common use of them. 2001 I had to move to Berlin because my wife was starting her own business there. My Zeiss boss suggested to approach OSRAM as they were producing projection lamps. So I continued working for the same customers and could make use of my former experience. The cultural difference was surprising: In Zeiss, there where teams executing projects, but in OSRAM was a „one man one lamp“ culture : for your lamp, you did everyting from optical design, ordering components, setting up life tests (including cleaning the burning racks), transfer to manufacturing and presenting the lamp to customers (mostly in Taiwan). I managed to introduce LightTools and new reflector design principles based on projector optics. These were quickly copied by competitors and are still on the market. Later, I became head of an LED Specialty Optics group with members in Germany and China. We tackled many fields where traditional lamps were to be replaced by specialty LEDs: Airfield lighting, surgcal lights, medical fiber light sources, gobo projection, stage lighting. The idea was the following: former lamp customers would start buying LEDs, and instead of just observing we would develop LED modules and try to sell them or even make products. Of course, some customers did not like the new competitor. In 2013, a new door opened and I decided to follow a technical career instead of a management path. I became a Pricipal Key Expert for Optical Design and concentrated on design, teaching, publishing, and leading the company internal optical design community which then consisted of more than 100 colleagues. At the same time, OSRAM went public which caused some organizational and cultural changes. In 2018, it was time to move on and my wife and me went to Switzerland. In FISBA, working culture was rather similar to Carl Zeiss, but other aspects were not. Switzerland was (and continues to be) an tremenduous experience. A strange language, different habits (but at a second glance really nice people) and an enormeous recreational value. We first lived in Winterthur where my youngest son finished high school („Papa: im Schwyzerdütsch gibt es zwei Zeitformen: Präsens und gsi“). Later we moved to the shore of Lake Constance and my wife became again a freelancing doctor. In 2025, my time at FISBA came to an end and I decided to pursue a long time dream and start my own optical consulting business. Now we are both freelancing which means some risk but a lot of opportunities. Here we are and the future looks bright. Publishing : Somehow I managed to publish during all the industry years and to serve the community in various functions. You can find my record here (be patient, it takes a moment to load). And now I even became a topical editor of Applied Optics . What a honor! The most useful journal for me.

Dr. Henning Rehn