Title

Optical coherence tomography instrumentation and application

Date of Completion

January 2006

Keywords

Engineering, Biomedical

Degree

Ph.D.

Abstract

Optical Coherence Tomography (OCT) is an optical imaging modality in coherent domain that is suitable for biomedical sub-surface imaging. This dissertation will present my work focused on the OCT instrumentation and aimed at its biomedical applications. The OCT infrastructure and its intrinsic principle will be discussed. The unmatched advantage of OCT, i.e. the high sensitivity and resolution imaging capability and the unavoidable limitation, i.e. the shallow imaging depth are just the natural consequence from the enfolded principle. ^ When polarization devices is added into the OCT, it becomes a Polarization-Sensitive Optical Coherence Tomography (PS-OCT) system. A free space PS-OCT system developed in the lab will be presented. To further improve the power of PS-OCT imaging, a new LP (Linear Polarization) and CP (Circular polarization) dual-configuration PS-OCT system (LPCP-OCT) was also designed and constructed. The dental imaging results showed that PS-OCT has great potential for dental applications. ^ When the phase or frequency parameter is measured and imaged from the OCT raw data, it becomes an Optical Doppler Tomography system. Optical Doppler Tomography (ODT) estimates the Doppler frequency shift, which is very sensitive to the sub-surface micro blood flow. An Adaptive Notch Filter (ANF) technique is developed for ODT with the concept of frequency tracking. This filter has excellent performance in term of noise robustness, estimation accuracy, and computational speed compared with other six common ODT algorithms. ^ At last, a novel hybrid radiation-plus-OCT catheter for cardiovascular imaging will be presented. The key issues for this intravascular imaging system will be discussed. A 4-channel fast peak-holding circuitry has been implemented for photon counting with a Position-Sensitive PMT. The preliminary imaging data from a rabbit model will be demonstrated.^