Figure 1

The morpho-chemical imaging system based on a combination of a forward-looking Raman probe and OCT probe. The Raman setup is built around a 785 nm single mode excitation source that is fiber-coupled to the Raman probe, which is mounted in parallel to the imaging OCT probe and focuses the excitation light onto the sample. The generated Raman signal is collected and guided to the spectrometer. The swept source OCT system is built around an akinetic swept-source laser, with a central wavelength of 1304 nm, a bandwidth of ~ 90 nm and a sweep frequency of ~ 173 kHz, which is connected through an 80:20 fiber optical coupler (FC) and a circulator (C) to the piezo-tube based scanning OCT probe. The setup includes the interferometric optical setup in Mach–Zehnder configuration with a dual balanced detector (DBD), polarization paddles for polarization management (PP) and driving electronics for the endoscope and a PC. The sample is observed by a brightfield camera and the region of interest can be selected by the user. Both systems are connected by an Arduino board, which is used to switch between Start-Stop the stage translation and data acquisition. M: Mirror, Coll: Collimator.