Flow Cytometry

Cytometry means to detect specific properties of single cells out of a large volume of cells. The cells can be detected and sorted according to special criteria like the presence of blood cells, cell core material or similar. A common method is Flow Cytometry were cells are marked with  bioactive molecules combined with dyes to be excited by a certain wavelength. The cells were suspended in a liquid stream which is narrowed to let only single cells pass. A laser beam hits the cells marked with dyes and sorting is possible depending on the fluorescence signal. To perform a really multiparameter analysis a lot of different dyes are necessary. Hence, the appropriate number of different laser wavelength has to be available. The required laser performance is usually lower than for applications in spectroscopy. Therefore, mostly laser diodes are used to illuminate the cells. However, due to the lack of suitable laser diodes in the green yellow range of the spectrum also diode-pumped solid-state laser are applied. Lasers for Cytometry have to show:

-     A large spectrum of available wavelengths

-     High power stability

-     Low noise

-     Long lifetime