Calibration procedure for enhanced mirror artifact removal in full-range optical coherence tomography using passive quadrature demultiplexing

Abstract

Significance: Passive quadrature demultiplexing allows full-range optical coherence tomography (FR-OCT). However, imperfections in the wavelength- and frequency-response of the demodulation circuits can cause residual mirror artifacts, which hinder high-quality imaging on both sides of zero delay. Aim: We aim at achieving high mirror artifact extinction by calibrated postprocessing of the FR-OCT signal. Approach: We propose a mathematical framework for the origin of the residual mirror peaks as well as a protocol allowing the precise measurement and correction of the associated errors directly from mirror measurements. Results: We demonstrate high extinction of the mirror artifact over the entire imaging range, as well as an assessment of the method's robustness to time and experimental conditions. We also provide a detailed description of the practical implementation of the method to ensure optimal reproducibility. Conclusion: The proposed method is simple to implement and produces high mirror artifact extinction. This may encourage the adoption of FR-OCT in clinical and industrial systems or loosen the performance requirements on the optical demodulation circuit, as the imperfections can be handled in postprocessing.