Hell hurried to the institute and took his first stab at a new principle of microscopy. It quickly became clear to him that the resolution would drop to at least 30 nanometers – one tenth of the previous limit. “At the time, the very idea was a sensation,” Hell says, recalling the most exciting moment in his professional career. “But it was also clear to me that, in principle, there was no lower limit.” He was in a fever of excitement for the rest of the weekend. “I sat alone for a day and a half with this strange feeling: I probably know something that no one else knows, and that could be hugely important.” He thought it through again, wrote it down and carried out a few rough computer simulations.
On Monday morning he was finally able to tell his colleagues and his boss. “He just looked at me, and I could see no reaction in his face whatsoever,” Hell recalls. The Finns, he says from experience, tend to be very restrained, not given to saying a lot. “Then I said, ‘It works, it works!’ And he replied dryly: ‘On paper.’” He was right, of course. In the beginning, it only worked on paper.
On a sunny day almost 16 years later, Stefan Hell sits in his spacious office at the Max Planck Institute for Biophysical Chemistry in Göttingen. He is one of the institute’s Directors, and heads the department of NanoBiophotonics. The phone rings. NATURE, one of the world’s leading trade journals, wants to run an article on Hell and his microscope and needs the latest images. And an industry colleague urgently needs to discuss the details of a joint grant application to the German Ministry of Education and Research (BMBF). Stefan Hell is in demand.
In his mid-forties now, dressed in black jeans and a white shirt, he looks relaxed as he sits at his desk. What few hairs were left have bowed to the razor, and his full lips curve easily into a smile as keen eyes look out through rimless spectacles set on a friendly face. He has arrived.
Stefan Hell’s novel microscope has since slowly matured. In his laboratories, it produces fascinating images of cells and neurons and showed, for the first time, how individual messenger vesicles bind with nerve terminals. The first versions are available for purchase and are already providing valuable services, helping biologists and medical researchers who are searching for the molecular causes of disease or studying how drugs work. The device might well be called a nanoscope, given its current resolution of around 15 nanometers – a feat that few would have considered possible.