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Welcome to the Bio- and Nano-Photonics research group

Head of the Laboratory


       Prof. Dr. Alexander Rohrbach

Email: rohrbach(at)imtek.de

University of Freiburg
Department of Microsystems Engineering - IMTEK
Laboratory for Bio- and Nano-Photonics
Georges-Köhler-Allee 102
79110 Freiburg
TEL. ++49 761 203 7536
TEL. ++49 761 203 7548 (secretary)


Research goals

Living cells are fascinating microsystems. Therefore we develop novel techniques for laser optical microscopy and optical force based applications, to investigate the biophysics of living cells and of bio-mimetic systems based on their nano-mechanics and thermal fluctuations.


Our research group


Please click on the picture to see our group taking off due to non-conservative forces
(or click here and here for alternative group pictures)


Click on the picture to view a movie of a live macrophage cell in contact with highly dynamic 100nm corona virus dummies: ROCS microscopy images at 10ms integration time (left) and edge enhancement (right).


Who said working in a lab isn't fun? Click on the video to see us doing our business!


Selected Publications

L. Friedrich, A. Rohrbach
Surface imaging beyond the diffraction limit with optically trapped spheres
Nature Nanotechnology 2015, issue 10, pages 1064–1069

M. Koch, A. Rohrbach
Object adapted optical trapping and shape tracking of energy switching helical bacteria
Nature Photonics 2012, issue 6, pages 680 - 686

F. Fahrbach, A. Rohrbach
Propagation stability of self-reconstructing Bessel beams enables contrast-enhanced imaging in thick media
Nature Communications 2012, issue 3, page 632

F. Fahrbach, P. Simon, A. Rohrbach
Microscopy with self-reconstructing beams
Nature Photonics 2010 , issue 4, pages 780 - 785

H. Kress, E. H. K. Stelzer, D. Holzer, F. Buss, G. Griffiths, A. Rohrbach
Filopodia act as phagocytic tentacles and pull with discrete steps and a load-dependent velocity
PNAS 2007, issue 104, pages 11633 - 11638

A. Rohrbach
Stiffness of optical traps: Quantitative agreement between experiment and electromagnetic theory
PRL 2005, issue 95, pages 168102



Yatish starts as a new PhD student in our lab.

A new research project ("The influence of particulate matter properties on the biophysical entry mechanisms into lung cells") will be funded for the next 3 years by the Deutsche Forschungsgemeinschaft (DFG grant RO 3615/17-1)

We are part of the DFG Sonderforschungsbereich SFB 1425 - Heterocellular Nature of Cardiac Lesions: Identities, Interactions, Implications! Alexander Rohrbach and Eva Rog-Zielinska will run project P11 ("Nano-Structural Basis for Mechanical Fibroblast-Cardiomyocyte Cross-Talk"). More info here: https://www.sfb1425.uni-freiburg.de/

New textbook "Wavefront Shaping for Biomedical Imaging" is published by Cambridge University Press and comprises a chapter about lightsheet microscopy by Alexander Rohrbach.

Alexander Rohrbach explains applications of optical tweezers in German television (3sat science documentary). >>> Link to 3sat media library, contribution starts at 6:42 min.

Rebecca Michiels successfully defended her PhD thesis. Congratulations!

New publication by Tobias Meinert in Biomedical Optics Express: "Light-sheet microscopy with adaptive Bessel beams" (>>> download pdf)

In honour of the recently awarded Nobel prize in physics, Alexander Rohrbach will give a talk about optical tweezers and ultrashort laser pulses, entitled "Manipulationen mit Licht: Von Laserfoki und Optischen Pinzetten". The talk takes place in the lecture hall of the physics department (13.12.2018; 17:15 o'clock) and is organized by the jDPG (junge DPG) Freiburg.

M.Sc. Niclas Trube, whose Master thesis was partly supervised by A. Rohrbach, has been awarded the Young Scientists Award at the Human Modeling Symposium 2018. Congratulations!

New publication by Dominic Ruh in Optica: "Superior contrast and resolution by image formation in rotating coherent scattering (ROCS) microscopy" (>>> download pdf)

Tetiana Udod starts as a new PhD student in our lab.

Dr. Tobias Meinert has been awarded the Wolfgang-Gentner-award for young scientists, thanks to outstanding achievements in his PhD thesis. Congratulations!

New publication by Hamideh Kermani in ACS Photonics: "Orientation-control of two plasmonically-coupled nanoparticles in an optical trap" ( >>> download pdf)

New publication by Felix Jünger in Cytoskeleton: "Strong cytoskeleton activity on millisecond timescales during particle binding and uptake revealed by ROCS microscopy" ( >>> download pdf)

New publication by Anjan Bhat Kashekodi in Biomedical Optics Express: "Miniature scanning light-sheet illumination implemented in a conventional microscope" ( >>> download pdf)

New publication by Julian Roth in Biophysical Journal: "Dynamics of a Protein Chain Motor Driving Helical Bacteria under Stress" ( >>> download pdf)

New publication by Matthias Koch in Biophysical Journal: "Label-free Imaging and Bending Analysis of Microtubules by ROCS Microscopy and Optical Trapping" ( >>> download pdf)

Tobias Meinert successfully defended his PhD thesis. Congratulations!

Matthias Allkemper starts as a new PhD student in our lab.

New publication by Cristian Gohn-Kreuz in Optica "Light-needles in scattering media using self-reconstructing beams and the STED-principle" ( >>> download pdf)

New publication by Mathias Koch in Nature Scientific Reports "Single microtubules and small networks become significantly stiffer on short time-scales upon mechanical stimulation" ( >>> download pdf)

A. Rohrbach rejects call from other university and accepts stay offer from the University of Freiburg

New publication by Tobias Meinert in Nature Scientific Reports "Separation of ballistic and diffusive fluorescence photons in confocal Light-Sheet Microscopy of Arabidopsis roots" ( >>> download pdf)

New publication by Felix Jünger in Nature Scientific Reports "Fast, label-free super-resolution live-cell imaging using rotating coherent scattering (ROCS) microscopy" ( >>> download pdf

New publication by Cristian Gohn-Kreuz in Optics Express "Light-sheet generation in inhomogeneous media using self-reconstructing beams and the STED-principle" ( >>> download pdf)

New publication by Benjamin Tränkle in Soft Matter "Interaction dynamics of two diffusing particles: contact times and influence of nearby surfaces" ( >>> download pdf)

New publication by Marc Blattmann in Nano Letters "Plasmonic Coupling Dynamics of Silver Nanoparticles in an Optical Trap" ( >>> download pdf)

Luis Köbele starts as a new PhD student in our lab.

New publication by Lars Friedrich in Nature Nanotechnology "Surface imaging beyond the diffraction limit with optically trapped spheres" ( >>> download pdf)

New publication by Felix Jünger in Biophysical Journal "Measuring local viscosities near membranes of living cells with photonic force microscopy" ( >>> download pdf)



Keywords / Schlüsselwörter


Optics, Photonics, Biophysics, optical traps, optical tweezers, particle tracking, microscopy, light-sheet, self-reconstructing beams, Bessel beams, light propagation, BPM, scattering, superresolution, TIRF, fluorescence, STED, hydrodynamic coupling, fluctuation, diffusion, molecular motors, mechanics of the cytoskeleton, visco-elastic theory, phagocytes, filopodia, bacteria, cell wall, vesicles


Optik, Photonik, Biophysik, optische Fallen, optische Pinzetten, Partikeltracking, Mikroskopie, Lichtscheibe, selbstrekonstruierende Strahlen, Bessel-Strahlen, Lichtpropagation, BPM, Streuung, Superauflösung, TIRF, Fluoreszenz, STED, hydrodynamische Kopplung, Fluktuation, Diffusion, molekulare Motoren, Zytoskelett-Mechanik, Visko-elastische Theorie, Fresszellen, Filopodien, Bakterien, Zellwand, Vesikel




Bio- and Nanophotonics
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