UBC Theses and Dissertations
Design and application of combined multiphoton microscopy and optical coherence tomography system Zhou, Yifeng
Optical coherence tomography (OCT) is a non-invasive optical tomographic technique based on the principle of interferometry. It can capture micrometer-resolution, three-dimensional images of tissues over millimeter field-of-view at a fast speed. Multiphoton microscopy (MPM) is an emerging imaging modality based on the excitation of nonlinear signals from fluorescent molecules and the induction of second harmonic generation (SHG). It is capable of en-face high-resolution imaging with sub-micron resolution. Although OCT and MPM are essential imaging tools for disease diagnosis, each one of them has shortages, such as the low resolution of OCT and the low depth penetration of MPM. The purpose of this study is to design a multimodal imaging system by combining MPM and OCT into a single platform so that the two modalities can complement and overcome the shortages of each other. The design consists of two parts: hardware and software. For hardware, the two modalities are integrated into a single platform, sharing the laser source, the controlling scanners and the sample arm. In addition, the OCT has a reference arm for interference and a custom-built spectrometer for signal detection, whereas the MPM uses two photomultiplier tubes (PMT) for photon detection. For software, two user interfaces are specially designed to control beam scanning and data acquisition of the MPM and OCT respectively. The performance of this mutlimodal system is demonstrated by imaging biological samples. The results indicate that our system is capable of multiscale imaging of multilayered tissues with clear structures. One of the important applications of the multimodal system is measuring the refractive index (RI) and thickness of biological tissues. This capability is demonstrated on fish cornea. The results show our system is capable of imaging as well as quantitative characterization of RI and thickness of multilayered biological tissues. This system can potentially be a powerful tool for disease detection and surgery treatment.
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