The test stand shown here is used for high-resolution Raman spectroscopy. This is particularly advantageous when many molecules overlap in a certain spectral range or the temperature needs to be determined with high accuracy. The modular design of the test stand allows the flexible alignment of different flow apparatus relative to the sample volume, which enables the investigation of a variety of processes.
A continuous wave laser is used to excite the Raman scattering in the sample volume. This is guided through a telescope into the multipass cell, where it is reflected several times between two parabolic mirrors in order to amplify the laser power. This also amplifies the inherently weak Raman scattering. The excited Raman and Rayleigh scattering is focussed onto the slit of the spectrometer via the achromat (L1), two objectives (L2 and L3) and a notch filter. The notch filter suppresses the excitation wavelength of the laser and thus the Rayleigh scattering. In the spectrometer, the incident light is split according to its wavelength and detected spectrally separated via the CCD chip of the camera. For a detailed description of the test stand, please refer to publications (1) and (2).
