The Importance of Learning Both the Great Potential of Optics and the Significant Practical Challenges of Meeting It

Wolfgang Osten

University Stuttgart, Germany

Remembering my university time at the Friedrich-Schiller University in Jena, Germany, I can only conclude that I had wonderful teachers. My area of study was physics, but I specialized in optics. This was mainly motivated by my fascination for holography so I made wrote my diploma thesis on Coherence Optics. One of the lectures that I was required to hear at the time was Optical Imaging. This lecture was given by Christian Hofmann, a manager from ZEISS and a visiting professor at the universities in Jena and Ilmenau.

I cannot remember any other lecture that was as unique in its speed and its depth as well. But two other peculiarities about Hofmann’s lecture shaped me in the long term and significantly influenced my attitude towards teaching optics. At any moment during his lecture, a student could interrupt him and ask questions. He would immediately stop his flow of words and his extremely fast writing on the black board and start to give another lecture off the cuff. We all then sat on our benches with open mouths, ears and eyes trying to follow his deep excursions into, for example, the wide field of electrodynamics. The other peculiarity was the way he taught us both the great potential and the challenges of designing optical systems with a high level of imaging quality. Thus, he did not start by writing Maxwell equations on the black board and deriving from them the features of light. He started by asking the question: What do we expect from an ideal optical imaging? The way he tried to answer that question became an excursion into the realm of Gaussian or paraxial optics—a purely mathematical response based on linear transformations and collineation. What we learned from it gave insight into what we can expect from optical imaging in the most ideal case and what the challenges are in designing a system that at least approximately fulfills the properties of an ideal system. This was, admittedly, a very dry start, which, however, opened up the view to what must be done in order to achieve a high level of imaging quality. The answers came later when geometrical optics, wave optics, aberration theory, photometry, and Fourier optics were extensively examined.

When I implemented a similar approach to my lectures at the Bremen and Stuttgart universities, the student response was at first ambivalent. My precursors had preferred a more classical or intuitive way of teaching. However, with time, and as the lectures progressed, the students and assistants understood the advantages of this approach and grew to appreciate not only the potential of optical imaging but also the challenges to achieving them.

In the flowchart on the next page, I have tried to visualize the interconnections of the different models for presenting and understanding the features of an optical imaging. I am convinced that there is always room to make a presentation even better. In any case, the biggest gift for me as a teacher of optics is seeing the glow in my students’ eyes and feeling their hunger to hear more when I talk about the great fascination of optics, as well as its significant challenges.

An attempt to visualize the interconnections and main peculiarities of different models for presenting classical optics.