Spectrometer-based Optical Coherence Tomography Systems with Extended Functionality

Optical coherence tomography (OCT) has evolved over the last two decades to become a major optical imaging modality in the biomedical optics field. By performing high-resolution, multi-dimensional imaging of translucent structures, it enables real-time tissue imaging in-vivo and in-situ with resolutions in the micrometre range.

This Thesis focuses on extending the functionality of spectral-domain OCT (SD-OCT) systems operating at 800 nm. On a secondary level, it also aims to address some of the performance issues involving SD-OCT, such as the ambiguity on the sign of the optical path difference and the finite axial range of the OCT system due to the sampling resolution limit of the spectrometer. Addressing these issues has been achieved through the modification of the spectrometer, exploring an effect first reported by William Fox Talbot in the mid-19th century, Talbot Bands, which effectively allows a degree of control over the SD-OCT visibility profile shape and position.

This extended functionality manifests itself by the addition of a confocal channel (applied to retinal imaging, hence creating a scanning laser ophthalmoscope, SLO), also by controlling the shape and position of the visibility profile with a novel spectrometer design employing Talbot Bands, which improves the power efficiency by coupling the two arms of the interferometer within the spectrometer itself.

Further functionality has been added to OCT technology by carrying out research on the interferometer at the core of the OCT system. A new single-detector, polarisation-sensitive OCT (PS-OCT) configuration, immune to disturbances caused by the collecting fibre was devised. This ultimately leads to a design of a plug-in PS-OCT module capable of enabling polarimetric measurements in any existing OCT system.