A fiber coupled and stabilized microscope for analytical CARS micro-spectroscopy

Abstract

This contribution presents an alternative setup for analytical micro-spectroscopy by means of coherent anti-Stokes Raman scattering (CARS). Instead of using separate detectors for forward- and epi-scattered photons, this setup enhances the comparability of the signals by coupling them into a multimodal optical fiber and employing a fiber optical switch for selection of the signal source at a single detector. To facilitate measurements at different spectral positions, which might be hampered by laser power fluctuations, a feedback loop is introduced into the pump beam to ensure stable and pre-defined laser power levels. The scheme of the microscope and the control software is presented. Its potential is evaluated by recording spectral data of model analytes as well as images of human skin.