Observing Nanoscale Dynamics in Living Cells by Breaking the Diffraction Barrier of Light

The diffraction limit of light has constrained the resolution of light microscopes in the far field since its discovery more than a century ago. Structures smaller than about half the wavelength of light could therefore not be resolved by (far field) light microscopes. The realization that this limit can be broken has triggered a revolution in imaging, especially in biological applications which heavily depend on light microscopy. By optically switching fluorescent molecules on and off, 25 nm spatial resolution or better, more than 10-fold better than in conventional microscopy, is now achievable! In my presentation, I will provide an overview of the different approaches that are currently developed and applied. I will focus on the physical basis of the techniques which allows identifying striking similarities of seemingly very different methods. I will present our latest achievements in the development and application of these techniques to provide examples of the current state of this exciting new field in physics.