Research Of Single-detector Polarization-sensitive Optical Coherence Tomography

Polarization-sensitive optical coherence tomography (PS-OCT) is a non-invasive, high-resolution medical functional imaging technology. It measures the change of birefringence in biological tissues caused by pathological changes, thus can diagnose the early diseases. PS-OCT is a powerful tool for research of tissue with high birefringence, and is effective in diagnosing diseases which is able to strongly change the birefringence of tissue.Till now, the research of PS-OCT focuses mainly on the dual-detector PS-OCT, while the single-detector PS-OCT is hardly touched. We proposed our single-detector PS-OCT in this dissertation, which detects the interference light oscillation caused by polarization changes of light traveling in biological tissue and describes the birefringence of tissue with the oscillation. Compared with dual-detector PS-OCT, our system simplifies the data processing, decreases the data quantum and lowers the expense.The main researches of this dissertation are shown as the following:1. A birefringent biological tissue model is built and the Stokes vector distribution of polarized light traveling in biological tissue is simulated with it. According to the simulation result and polarized light interference theory, the principle of single-detector PS-OCT detecting tissue birefringence is presented.2. Design a single-detector PS-OCT, and build the signal-to-noise ratio (SNR) model according to it. The influence of four different optical system structures on SNR is simulated. Compare the highest SNR of optical system with each structure. The analysis is taking as the key to choose suitable optical system structure in single-detector PS-OCT.3. Build up a biological tissue model, according to which simulations are done to find out the relationship of A-scan signal FFT and different tissue character. Since the FFT indicates the gray scale distribution in PS-OCT image, which describing the tissue character, the result ensures the possibility of single-detector PS-OCT detecting biological tissue character, such as thickness, refractive index and birefringence.4. Taking fresh bovine cartilage as sample, achieve the 2D imaging with single-detector PS-OCT. The gray scale image shows the stripes indicating the tissue birefringence. The birefringence of bovine cartilage calculated in our experiment has only small difference with the known value which is bearable, validating the feasibility of our system.5. Construct a dual-detector PS-OCT, and get phase image of biological tissue with it. The comparison of dual- and single-detector PS-OCT image verifies the feasibility and reliabiliby of our single-detector PS-OCT.