It’s a familiar situation for all car drivers. In the autumn, when the roads are foggy, visibility drops below 50 metres. The light of the car’s headlights are scattered by the drops of fog, meaning we can’t see objects further away because the light can’t reach them.
This everyday example illustrates a key problem of light microscopy. When used in modern cell biology, the dense clusters of thousands of cells scatter the light so strongly that the cells located in the back of an object can hardly be seen. Although better known from science fiction, the concept of self-reconstructing laser beams offers a promising solution to the problem.
Together with his team of scientists, Dr. Alexander Rohrbach, Professor for Bio- and Nano-photonics at the University of Freiburg’s Department of Microsystems Engineering – IMTEK, is developing new, unconventional techniques in microscopy “whose physical concepts are at least as exciting as their technical realisation,” Rohrbach said. His doctoral student, Florian Fahrbach, whose research focuses on self-reconstructing laser beams, added, “We’ve been working on this for the last four years.
Without the support of the Freiburg Cluster of Excellence BIOSS – Centre for Biological Signalling Studies and Carl Zeiss MicroImaging GmbH, it would have been very difficult to realise the concept we’re now presenting!” Rohrbach is also pleased: “We managed to achieve a direct transfer from basic research to application in the form of a new microscope. That's definitely what most researchers want!”
In the forthcoming November issue of Nature Photonics the scientists describe their new light microscope, which relies on beams that reconstruct themselves in light-scattering media. The new method not only provides novel insights into the physics of complex light scattering, but it also enables, for example, to look about 50 percent deeper into human skin tissue than with conventional laser beams. The scientists have named their new invention MISERB (microscope with self-reconstructing beams).
The researchers from Freiburg were able to demonstrate in several experiments that specially formed laser beams are able to self-reconstruct even in the presence of various obstacles, for example a high number of light-scattering biological cells, which repeatedly destroy the laser beam’s profile. Self-reconstruction works because the scattered photons (light quanta) at the centre of the beam are constantly replaced by new photons from the side. What is so astounding is that the photons from the side all converge at the centre of the beam nearly in phase in order to build a new beam profile, undeterred by considerable lags from the scattering. The scientists therefore used a computer hologram (a device that changes the phase of light) to modify conventional laser beams into so-called Bessel beams whose phase profile has the shape of a cone. Although Bessel beams are known to be diffraction-free in free space, it has been completely unclear whether, and to what degree, they are able to regain their original beam shape also in inhomogeneous media, where light scattering is considerable.
Not only do the results of this study have the potential to generate more exciting physical experiments in the field of nonlinear optics, but the BIOSS Cluster of Excellence also has reason to hope that it will make new biological signal cascades deep inside living organisms more visible than ever before.
Melanie Hübner | alfa
Multi-year study finds 'hotspots' of ammonia over world's major agricultural areas
17.03.2017 | University of Maryland
Diabetes Drug May Improve Bone Fat-induced Defects of Fracture Healing
17.03.2017 | Deutsches Institut für Ernährungsforschung Potsdam-Rehbrücke
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
27.03.2017 | Earth Sciences
27.03.2017 | Life Sciences
27.03.2017 | Life Sciences