Multimodal laser-scanning nonlinear optical microscope with a rapid broadband Fourier-transform coherent Raman modality

Abstract

Nonlinear optical microscopy allows for rapid high-resolution microscopy with image contrast generated from the intrinsic properties of the sample. Established modalities, such as multiphoton excited fluorescence and second/third-harmonic generation, can be combined with other nonlinear techniques, such as coherent Raman spectroscopy, which typically allow chemical imaging of a single resonant vibrational mode of a sample. Here, we utilize a single ultrafast laser source to obtain broadband coherent Raman spectra on a microscope, together with other nonlinear microscopy approaches on the same instrument. We demonstrate that the coherent Raman modality allows broadband measurement (>1000 cm-1), with high spectral resolution (<5 cm-1), with a rapid spectral acquisition rate (3-12 kHz). This enables Raman hyperspectral imaging of kilo-pixel images at >11 frames per second.