Spatially multiplexed swept source optical coherence tomography

A spatially-multiplexed swept-source optical coherence tomography (SM-SS-OCT) system for rapid acquisition of B-scans of tissue microstructure is described, we believe, for the first time. SM-SS-OCT instrumentation is similar to that of traditional Swept Source OCT (SS-OCT), which uses a widely tunable (~100 nm) laser source to obtain high-resolution images of biological tissue. However, SM-SS- OCT may be considered an improvement over SS-OCT in terms of efficient usage of the wide spectral bandwidth afforded by the frequency-tunable lasers in SS-OCT systems. Commercially available swept-source lasers regularly achieve extremely narrow line widths (~150 KHz), allowing for SS-OCT A-scan depths on the order of meters. Since imaging tissue to such depths is infeasible, the meters-long depth ranging capability of SS-OCT may be utilized for spatially multiplexing many A-scans, each to lesser depth. We achieve this spatial multiplexing by rapidly scanning all lateral positions of the tissue repetitively while simultaneously scanning the laser wavelength continuously, and using appropriate signal processing to reconstruct a B-scan image from acquired data. Our fiber-based design lends itself towards use in endoscopic applications, and our results suggest that SM-SS-OCT can provide rapid acquisition of B-scans, with potential for depth-resolved visualization of transient processes in biological tissue.