Spectral focusing dual-comb coherent anti-Stokes Raman spectroscopic imaging

Coherent Raman microscopy provides label-free imaging by interrogating the intrinsic vibration of molecules. Here, we present a concept in a 100 MHz dual-comb scheme to facilitate high-speed and broadband coherent anti-Stokes Raman spectroscopic imaging based on down-converted, automatically varying delay-time in spectral focusing excitation. A rapid measurement of vibrational microspectroscopy on submicrosecond scale over a spectral span ∼700 cm−1 with a refresh rate of 1.2 kHz provides access to well-resolved molecular signatures within the fingerprint region. We demonstrate hyperspectral images of a mixture of spatially inhomogeneous distributions of chemical substances.