Fd-the Oct To The Complex Conjugate Imaging Study

Optical coherence tomography (OCT) based on low coherence interferometer combining with confocal scanning microscopy and heterodyne detection technology, provides cross-sectional images of the internal microstructure of living tissue with micrometer resolution and millimeter imaging depth. OCT has been an attractive tool for high-resolution and non-invasive biomedical imagingDuring the past few years, Fourier-domain optical coherence tomography (FD-OCT) has become an attractive alternative to conventional time-domain optical coherence tomography(TD-OCT) because it has been demonstrated, both theoretically and experimentally, that FD-OCT has the potential to provide better sensitivity and dynamic range than TD-OCT. However, a major drawback of FD-OCT that limits its practical use is the complex-conjugate ambiguity, which is inherent to real Fourier transforms, and only one half of the imaging depth range is useful in practice. Resolving the complex-conjugate ambiguity would double the imaging depth range and provide additional flexibility by allowing arbitrary positioning of the zero plane.Resolving the complex-conjugate ambiguity is the main work of this thesis. Researching the theory and approaches of resolving the complex-conjugate ambiguity, using sine wave phase modulation and harmonic demodulation combining B-M-mode removes the artifact based on SD-OCT system in our lab. Five chapters are included in this thesis:Chapter 1: The background, main work and approaches of carrying out this thesis.Chapter 2: The fundamental theoretics of Fourier domain optical coherence tomography (FD-OCT).Demonstrate the fundamental theoretics of OCT,the status of research, development trend and applications. The fundamental theoretics,system,and features of FD-OCT are outlined. Analyze the cause of the artifact.Chapter 3: Approaches of resolving the complex-conjugate ambiguity. Study difference resolving methods and complex-conjugate rejection ratios.Chapter 4: Experiment result and data analysis, which is the key chapter in this thesis. Using sine wave phase modulation combining B-M-mode construct complex interferogram and get the complex-conjugate ambiguity removed. Analyze the difference between our approach and sine wave phase modulation. Harmonic reference is outlined. Get the parameters of the experiment, particularize the flow of signal process,analyse the error and the complex-conjugate rejection ratio.Chapter 5: Conclusion and expectation. In this chapter, the conclusions of the thesis are made, and further improvement in the future are also proposed...