Compensating pulse-to-pulse fluctuations and increasing spectral reproducibility of phase-matched CARS measurements.

The compensation of pulse-to-pulse fluctuations and the improvement of spectral reproducibility of scanned coherent anti-Stokes Raman scattering (CARS) spectra of dispersing media are discussed. A simple reference CARS setup is presented that needs a minimum number of optical components as a result of using the same optical path for both signals. Variations in spectral profile were found to be caused by mechanical play in the translation stage, which is used to adjust the matching angle. Using retroreflection, the matching angle adjustment is made insensitive to these mechanical imperfections. The multiple interference of probe and signal beam that may occur in thin cuvette walls and its effect on the detected CARS signals are shown, and possible solutions are discussed.