Stimulated Raman scattering spectroscopic optical coherence tomography*

Stimulated Raman scattering (SRS) enables fast, high-resolution imaging of chemical constituents important to biological structures and functional processes in a label-free manner. While this technology has shown remarkable potential, acquisition of SRS signals remains largely limited to point scanning at a few Raman bands. To overcome this limitation, we take advantage of the fact that SRS is a coherent process and can thus be integrated into a single platform with spectroscopic optical coherence tomography (SOCT). SOCT is an extension of OCT that leverages the broadband nature of low-coherent light sources, along with advanced digital signal processing methods, to simultaneously obtain three-dimensional spatial and spectral information, but SOCT has very limited endogenous molecular targets. Thus, the combined approach, termed SRS-SOCT, overcomes limitations of both individual methods and achieves fast, volumetric, and highly sensitive label-free molecular imaging. Here we will present a theoretical framework for SRS-SOCT, discuss its advantages and limitations, and show experimental results from excised tissues.