Time-independent dispersion compensation in rapid-scanning optical coherence tomography

We demonstrate a new method for simultaneous compensation of time-dependent and time-independent second- and third-order dispersion mismatches in an optical coherence tomography (OCT) system. There have been several methods for dispersion compensation in scanning interferometry by translating or tilting the diffraction grating in a rapid-scanning optical delay line (RSODL). Although these methods can provide a time-independent or time-dependent compensation of the second- or third-order dispersion, they cannot compensate the dispersion mismatch at both orders at the same time. However, the effects of both orders of dispersion mismatch caused by different lengths of fibers in the sample and reference arms in a fiber-based OCT system are significant and cannot be neglected. In this paper, we propose a new method for simultaneous compensation of time-dependent and time-independent second- and third-order dispersions by placing and adjusting a prism between the grating and the lens of the RSODL. The resulting dispersion can be calculated from the phase response of the RSODL with ray tracing analysis. The dependence of each order of dispersion on the configuration of the system is discussed with numerical analysis. The effects of the dispersion compensation are demonstrated with experiments.