High-sensitivity coherent anti-Stokes Raman scattering microscopy with two tightly synchronized picosecond lasers

We demonstrate a significant improvement in signal-to-noise ratio in coherent anti-Stokes Raman scattering (CARS) spectroscopy/microscopy, using two highly synchronized picosecond Ti:sapphire lasers. A temporal jitter between the pulse trains from the two independent commercial lasers is reduced from a few picoseconds to similar to21 fs. maintained over several hours. The tight synchronization brings the fluctuation of the CARS signal down to the shot-noise limit. leading to enhanced CARS vibrational images of living cells and polymer beads. (C) 2002 Optical Society of America.