Combined multiphoton microscopy and optical coherence tomography using a 12-fs broadband source

Abstract

A $12-fs$ broadband $(100-nm)$ source is used to combine multiphoton microscopy (MPM) and optical coherence tomography (OCT) in a single platform. An ultrafast Ti:sapphire laser simultaneously provides short pulses necessary for efficient MPM excitation and the broad bandwidth required for high-resolution OCT. Using $0.3-μm$ microspheres and a $63×$, 0.95 numerical aperture objective, we demonstrate that MPM and OCT channels are coregistered with lateral resolution of approximately $0.5μm$ and axial resolution of approximately $1.5μm$. Preliminary studies of a 3-D organotypic epithelial tissue model show that multiphoton images of fluorescence and second harmonic signals are derived from cellular and extracellular matrix structures, respectively, while OCT images are generated from scattering interfaces due to tissue variations in refractive index. The combined MPM/OCT microscope is capable of providing simultaneous functional and structural information from cells and extracellular matrix and is potentially a powerful tool for studying biological processes in thick tissues.