Fast super-resolution microscopy by rotating, coherently scattered laser light

• Applicant: Professor Dr. Alexander Rohrbach
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2019 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 413220392

The exploration of ever smaller and thus more dynamic structures represents one of the biggest technical challenges of the presence and the future. Long known physical laws seem to set immovable metrological barriers, such as the optical resolution limit in microscopy. It has turned out that many of these barriers can be bypassed with resourceful tricks, without moving the barriers. The smaller the structures to be spatially resolved in light microscopy, the more photons and measurement time are required. However, the smaller the structures in living systems, the faster they move and the less measurement time is available.In this initiative we work on a novel optical microscopy concept, where objects are illuminated coherently and images are generated coherently as well. By exploiting defined multiple interferences under oblique illumination and angular integration of many coherent images, a spatial resolution of nearly 100nm can be achieved in principle, at a temporal resolution of typically 100 Hz and with excellent image contrast. Within the preliminary work of our group, we could achieve a spatial resolution of 150 nm through rotating coherently scattered (ROCS) laser light in TIR-dark-field mode. With this technique we could acquire thousands of images without loss in image quality (e.g. fluorophore bleaching in fluorescence microscopy) and without image reconstruction (as required e.g. in super-resolution microscopy with structured illumination).In the present research proposal, we want to reach two new goals in addition to the expected 120 nm spatial and 100 Hz temporal resolution of this technique. On the one hand, we want to distinguish specifically marked structures in the image through specific absorption and phase retardation of the scattered laser light. On the other hand, we will develop a novel kind of time-correlated microscopy shall be developed - largely independently of the first goal. Here coherent ROCS images of label-free structures with high temporal resolution will be correlated to fluorescence based images of fluorophore distributions with low temporal resolution.

• DFG Programme: Research Grants