Research On Key Techniques Of Swept Source Optical Coherence Tomography System

Optical coherence tomography(OCT)technology based on the theory of low coherence interference,it has the advantages of non-invasive,no radiation and high resolution and so on.The OCT technology includes time domain OCT(TD-OCT),spectral domain OCT(SD-OCT)and swept source OCT(SS-OCT).The SS-OCT technology not only has the ability of quick imaging but also the advantage of point probe.So it's research meaning is higher than the others OCT technology,especially in the filed of high scattering biological tissue imaging.SS-OCT technology has became the mainly OCT technology for OCT research team.After full research,it has been found that swept source's wavelength of most SS-OCT system are 1000 nm or 1310 nm,not 1550 nm.So the key technology of SS-OCT with wavelength of 1550 nm has been studied in this thesis.Specific research works includes :1.A theory model of SS-OCT system based on the low coherence interference theory and fourier transform principle has been built.The system's parameters has been analyzed such as noise-signal ratio,sensitivity,resolution,imaging depth and imaging speed.Furthermore,the factors of each system's performances has been analyzed.So the design parameters of SS-OCT system has been got,besides,a theoretical foundation for the next research has been made.2.Design imaging software is a key link to the SS-OCT system.The method of data-processing and image reconstruction has been analyzed,on this basis,the algorithm of spectral calibration,spectral shaping,FFT transform,gray mapping and image reconstruction has been designed.In addition,the software from data-processing to image reconstruction has been programmed based on the development environment of VC++6.0.3.In order to get symmetrical interference spectrum in wave-number space,the spectrum need to be calibrated.In this thesis,three kinds of calibration method have been introduced: pre-calibration method based on system,real-time calibration method based on auxiliary interferometer and automatic calibration method based on the K-trigger of swept source.Advantages and disadvantages of these methods has been analyzed which will be helpful to the further research.4.A SS-OCT system has been built with wavelength of 1550 nm consists of three parts.Light path includes swept source,interferometer,sample arm and reference arm and so on.Hardware includes detector and data acquisition card.The axial resolution of this system is 15.1 ?m and the imaging depth is 7.69 mm in theory.Images of different samples has been got,and the performance of the system has been tested.Practically,the axial resolution of this system is 27 ?m and the imaging depth is 4.5mm...