Research Groups

UV Radiation

Group Leader: Axel Kreuter

Current UV-Index in Austria:

Latest measured UV-Index in Innsbruck:


We are interested in various aspects of solar radiation with emphasis on the UV spectral range. We develop new spectroradiometric instruments and analysis techniques and measure solar radiation spectra and aerosol optical depth in Innsbruck and during dedicated campaigns. We also operate the Austrian UV measurement network.

see also: UV-Index

Biomedical Laser Applications

Group Leaders: Monika Ritsch-Marte, Stefan Bernet


Optical Micromanipulation



Optical micromanipulation stands for contact-free handling of microscopic particles with laser light. With "Optical Tweezers" one can handle microscopic particles such as micro-organisms, micro-beads, living cells, cell organelles, or DNA-strands.

Our group has developed methods to shape optical trapping patterns with computer-holography methods. Moreover, we strive at pushing the limits of trapping towards increasingly large particles, including fast swimming organisms such as flagellates or Euglena species.

SLM-aided optical imaging:

We use miniaturized liquid crystal displays (LCDs) with individually addressable micrometer-sized pixels, so-called Spatial Light Modulators (SLMs), to advance optical microscopy.

SLMs can emulate contrast mechanisms (e.g. brightfield, darkfield or phase contrast), create multiplexed images (combining different imaging settings in one recorded image), and steer or pattern the illumination in the microscope.

Chemical imaging with Coherent anti-Stokes Raman Scattering (CARS)

If the frequency difference of two laser beams matches a Raman-active vibration of targeted molecules, a blue-shifted anti-Stokes signal is generated. This effect can be exploited for spectroscopy. Due to its coherent nature, CARS can lead to much higher signal strengths than e.g. Raman spectroscopy.

The combination of CARS with microscopic imaging leads to CARS microscopy, which enables fast recording of chemical maps on micrometer scale.

From a practical point of view, CARS microscopy resembles fluorescence microscopy, but without the need for fluorescent dyes.

We have developed a non-scanning CARS microscope where an extended area in the sample plane is simultaneously illuminated by pump and Stokes beams under phase matching conditions.

More information: