So, dear colleagues, specifically dear young colleagues, I appreciate that I have the opportunity

to talk to you about research, entrepreneurship and the virtue of limits. Maybe the title

is a little bit strange for you, or I have to explain what you can expect. So, this talk

will be about optics, but a major topic will be about meta-thinking about research. And

the major motivation is, can we teach inventing? So, this headline was created by my former

teacher, Adolf Lohmann. You see him here on the right side at his eightieth birthday,

six, seven years ago. And this is the famous Lohmann matrix, invention matrix. So, what

you see here is the question, you have a walking stick with a knob here and it looks like this

here or it may look like this. The handle may look like this. And the other, the remaining

question is, of course, is there an option for a new pattern? I think everybody will

immediately see what the pattern would be, what would be the handle and the foot like

it is. So, that sounds a little bit simple, but simplifying is in many cases the trick

in order to understand what's going on. So, this talk is an essay, it is an attempt to

distill rules for finding important questions, for becoming inventive, I think we all want

to be inventors, and for efficient research. And I will explain these rules by optical

examples of course. Okay, this talk is a retrospective about optics after 35 years of research. I

didn't know that 35 years ago when I was a young researcher like you, but I wish I would

have known this 35 years ago. So, I thought why not tell the young people this? Because

I would have been told this 35 years ago, nobody did. Okay, the plan is that I briefly

go through my personal story and then I would talk about the virtue of limits with optical

examples and the final chapter will be research and entrepreneurship in a nutshell. So, my

personal story, very brief, is I started as a young student 1968 at the Institute for

Optics, Technical Optics at the Technical University in Berlin and the wonderful thing was, or

maybe not so wonderful, I was the only undergraduate student at the Institute because optics was

out of fashion at that time. So, you know, all these lenses with scratches and the mountings

of the lenses are with all these brass things. So, it was not very, it doesn't look like

the Max Planck Institute now, didn't look at that time, but what can we learn from this?

The laser was invented a couple of years earlier, Fourier optics came into fashion and optics

is now a blossoming kind of research. So, what we can learn is do what you really like.

Personally, I was interested in optics even when I was a young boy, I built telescopes,

so I did what I wanted and not what was useful. Then I came to the University of Erlangen

and this is a short story as well. At that time, Professor Lohmann was a professor at

the San Diego and he moved to Erlangen and Lohmann was a very famous person, most of

you will know him and as a young doctor student or post-doc, I took my heart and my hand and

sent him my dissertation and that was really a little bit courageous because this big guy

said, alas, I got an answer, a letter, he said he found some errors in my dissertation,

but he said it's a good dissertation, won't you come to Erlangen and work with me? And

that was luck. If I wouldn't have done that, I wouldn't be here, definitely. So, what we

can learn is create chances, create chances and try to work together with good people.

So go abroad, find good people. So, what happened then? The real trouble begins always when

you got what you wanted. So I was at Erlangen with the big boss Lohmann and of course I

did what all the young scientists do, I worked at different institutions, but the real problem

was what should I do? So what should the topic of my research be? We played around with optical

image processing, optical feedback, we even made a video for Spektrum der Wissenschaften,

make American, we worked with chaos, newer networks. So, what can we do? We are scientists,

we have time, we have a little money, we have the freedom to do something and of course

we should take care about this freedom and do something important, but what? And this

is a big part, major part of my talk, find out what is an important problem, find an

important problem. So we found one after we skipped the newer networks and chaos, we found

an important problem in our group, it is the perfect 3D sensor, make it, understand it,