| Summary: | 碩士 === 國立成功大學 === 光電科學與工程研究所 === 96 === The technique of optical interference with the low coherence interferometry (LCI) having already the extensively application in optical biomedical imaging system of optical coherence tomography (OCT). The greatest characteristic of this imaging scheme, lie in high non-invade measurement、 high system resolution、 and Real-Time Imaging speed, therefore it has the greater advantage in this respect with Fourier domain optical coherence tomography (FD-OCT) system. FD-OCT system using the method of capture spectral interferogram not only improves the imaging acquisition time, but also promote the system sensitivity. In order to promote the analysis of imaging speed and ability, the phase-shifting method has an important situation to provide the larger advantage for system demodulation and imaging speed in OCT system. For this, in this paper, we propose a new system, it is right to combine the parallel diffraction grating (Parallel Diffraction Gratings Pair) Image, model of linear group delay promote the accuracy of phase-shifting method and improve the analysis process with FD-OCT system. We utilize parallel diffraction gratings pair to separate the characteristic of the space frequency spectrum to make linear group delay under the space distinguish for the postponement time among each different wavelength with the land in time, is it with space characteristic that distance postpone that get that frequency spectrum correspond to, design every time interval of frequency band to produce the linear group delay characteristic and provide the near π phase-shifting improving the efficiency of traditional phase-shifting method , and then improve the ability and stability of optical systematic scanning.
In these, comparison of the imaging analysis between traditional λ0/4 method and group delay based method by the different condition of sample structure of single layer、multi-layers respectively. By the simulation and analysis result, this technique of group delay based phase-shifting method has better system efficiency and inaccuracy proportion to provide the accuracy of FD-OCT imaging system than traditional method.
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