Improving the detection of cancerous cells during surgery is the goal of the European research project CARMEN. The research institutes Laser Zentrum Hannover e.V. (LZH) from Germany and Multitel asbl from Belgium are work with companies from both countries, JenLab GmbH, DELTATEC, and LaserSpec, to develop a novel, compact and multimodal imaging system. It is hoped that this will allow the examination of tissue samples directly during surgery.
Laser-based microscopes usually use only one imaging method, such as confocal microscopy, multi-photon microscopy or Anti-Stokes Raman Spectroscopy (CARS). Combining different imaging techniques in a single device makes it possible to obtain faster, more and more reliable information about tissues and possible diseases. However, the various excitation lasers needed would make a complete system very complex, bulky and expensive.
The partners in the CARMEN project want to develop an innovative laser system that generates several excitation wavelengths and different pulse durations. This would allow them to combine CARS with multi-photon and super-resolution STED (Stimulated Emission Depletion) microscopy in one compact device. Such a system would make it possible to examine tissue samples directly after the surgery or even during it. This would help to recognise tumuor margins more accurately, for example. Combining three methods allows the superimposition of several levels of information and thus a more precise picture of the cells can be obtained, making it easier to distinguish cancerous cells from healthy cells.
In cooperation with the Belgian research institute Multitel, the scientists at LZH are working on a novel fibre-based ultrashort pulse source for the novel laser system. The source will synchronously pump two optical parametric oscillators from the Belgian company LaserSpec. The entire laser system will have multiple beam outputs with tuneable wavelengths and be able to generate pulses simultaneously in both the femtosecond and picosecond ranges. This would be the basis for combining the three imaging methods in a multimodal system, which will be designed by JenLab. DELTATEC will develop an extremely fast electronic system, which will control the multimodal system. The electronic system also links the laser system with the scanner technology of the microscope.
Due to glass fibres’ favourable thermal properties, air-cooling will be sufficient for this novel fibre laser-pumped ultra-short pulse laser. This would make the imaging system cheaper, more energy-efficient and smaller than comparable microscopes with titanium-sapphire lasers, for example. The range of applications could also be expanded enormously: the system could track drugs and nanoparticles in tissues and cells, or could be used for microscopic testing of the effectiveness of cosmetic products.
