Development Of Phase-sensitive Spectral Domain Optical Coherence Tomography

Optical coherence tomography (OCT) is a non-invasive imaging modality with micrometer resolution. By employing phase-sensitive measurement, picometer-to-nanometer-scale phase sensitivity can be achieved in OCT, allowing for various applications such as cellular imaging, material inspection, and Doppler flow measurements. In this dissertation, the work is mainly focused on the development of phase-sensitive spectral domain optical coherence tomography. The main contents are as follows:1. Spectral domain OCT system has been studied, and the interferometer, sample arm, and spectrometer have been altered for phase-sensitive detection. The theory of phase-sensitive spectral domain OCT has been investigated, depth domain phase based approach and spectral domain phase based approach have been compared.2. Multi-spectral averaged phase-sensitive OCT has been presented. Uncertainties of recovered phases in spectral domain are investigated in theory and experiment. Multiple spectral phases from different spectral channels are fully exploited to determine the final optical path difference. High-sensitive quantitative phase detection is realized by the proposed method.3. A joint spectral and depth domain phase-sensitive OCT has been proposed. By theoretical derivation and simulation, the sensitivity advantage of phase information in depth domain over phase information in spectral domain is investigated. The phase retrieval is realized in the depth domain to maintain a high sensitivity, while the phase information obtained in the spectral domain is exploited to extend the dynamic range of optical path difference. The performance of the proposed method is illustrated by phase measurement of a coverslip, a resolution target and an onion skin.