Heterodyne CARS measurement of inhalational anesthetic molecules using adaptively phase-modulated femtosecond pulses

Coherent anti-Stokes Raman scattering (CARS) microscopy has been used as label-free imaging due to characteristic frequencies of chemical bonds. However, previous CARS measurement had several drawbacks. First, the conventional CARS microscopy requires two or three laser beams adjusted both spatially and temporally under a microscope. This multi-beam scheme makes these experiments difficult for daily use. Second, simultaneous measurement of multiple vibrational modes is required as an overall view of a specific molecular signature. Finally, the non-resonant background contribution distorts the measured spectral profile. Data processing of background extraction is not straightforward for retrieving the actual Raman spectrum.