Abstract

Coherent Antistokes Raman Scattering (CARS) is a very powerful approach for label-free vibrational imaging of biological and chemical compounds with high spatial resolution and acquisition speed [1]. In its most typical implementation it requires two narrowband pulses - pump (frequency ω_p) and Stokes (ω_s) - to be focused on the sample and their difference frequency to be tuned to a Raman-active molecular vibration. When this occurs, a strong anti-Stokes signal is generated, providing a chemically specific signature that can be used to uniquely identify the molecule. The most significant intrinsic limitation of CARS is the presence of a non-resonant background that does not carry any chemically specific information, and that is generated both by the molecular species under study and by the surrounding medium according to a four-wave mixing scheme.

© 2009 IEEE