Endoscopic long range fourier domain optical coherence tomography (LR-FD-OCT)

An endoscopic swept-source Fourier Domain optical coherence tomographic system (FDOCT system) for imaging of tissue structure comprising:

• a Fourier Domain mode locked (FDML), high speed, narrow line-width, wavelength swept source;
• an OCT interferometer having a sample arm, a reference arm, a detection arm, and a source arm coupled to the swept source;
• an endoscopic probe coupled to the sample arm;
• and
• a data processing circuit coupled to the detection arm,
• where the swept source comprises a long single mode optic fiber functioning as a cavity, a high optical gain lasing module, and a tunable narrow bandwidth bandpass filter for wavelength selection combined to form a unidirectional ring laser cavity, driven synchronously with the optical round-trip time of a propagating light wave in the cavity, and operating, where the tunable filter operates in a multi-band mode by simultaneously filtering two or more wavelengths at different spectral bands so that the swept source has an output comprised of multi wavelengths within different spectral bands and further comprising at least two wavelength-division multiplexing (WDM) couplers in optical circuit in the detection arm of the OCT interferometer, where the WDM couplers pass-band match the spectral bands of the filter and where the OCT interferometer divides the spectral bands into separate channels for detection.