A simple, robust and cost-effective method to achieve dispersion matching in swept source OCT

Optical path length and dispersion matching in both measurement and reference arms of an OCT system is critical for achieving bandwidth-limited axial resolution. To minimize or eliminate dispersion mismatch, most, if not all, fiber-based OCT realisations employ a reference arm configuration that is as closely identical to the measurement arm as possible. This typically includes a collimator, dispersion compensating material (or sometimes a set of lenses), as well as a mirror (or retro-reflector) mounted on a translation stage. However, this solution makes the total instrument cost higher and the setup bulkier than necessary and it also renders the reference arm mechanically unstable. Here, a simple yet robust, low-cost reference arm setup is presented and its ability to compensate for measurement arm dispersion is demonstrated. We use a single-mode fiber cleaved and polished perpendicular to the fiber axis to construct the reference arm. The length and material of the fibre is determined by considering the optical path length and dispersion of the measurement arm. Experimental images demonstrate the operation of the novel reference arm in our Swept-source Optical Coherence Tomography.