Optical parametric oscillator-based light source for coherent Raman scattering microscopy: practical overview.

We present the assets and constraints of using optical parametric oscillators (OPOs) to perform point scanning nonlinear microscopy and spectroscopy with special emphasis on coherent Raman spectroscopy. The different possible configurations starting with one OPO and two OPOs are described in detail and with comments that are intended to be practically useful for the user. Explicit examples on test samples such as nonlinear organic crystal, polystyrene beads, and fresh mouse tissues are given. Special emphasis is given to background-free coherent Raman anti-Stokes scattering (CARS) imaging, including CARS hyperspectral imaging in a fully automated mode with commercial OPOs.