以低同調干涉術(LCI)為基礎的光學斷層掃描術(OCT)已被廣泛的應用於生物醫學影像擷取中。光學斷層掃描術最大的特色,在於其系統的非侵入式量測、高解析度及即時取樣速度，而頻域光學斷層系統在(FD-OCT)此方面有較大的優勢。頻域光學斷層系統利用干涉頻譜的量測方式，不僅提升光學斷層系統的取像速度，也改善其系統的靈敏度。為了提升頻域光學斷層系統的取像分析能力及速度，相位偏移的演算理論占有不可或缺的地位，對於在樣品測量分析有較優勢的系統解析以及分析速度。在此，我們提出一套新的系統，結合平行繞射光柵對(Parallel Diffraction Gratings Pair)模組的影像擷取系統來提升相位偏移演算理論的正確性，並且有利於提升頻域光學斷層系統的分析。我們利用平行繞射光柵對模組的空間頻譜分離特性，在空間以及時域上區分出各個不同波長間的延遲時間，利用不同頻譜所對應到的空間距離延遲之特性，加以設計各頻段的時間間距，製造出線性群速延遲(linear group delay)的特性，產生更接近於π相位偏移值來改善傳統的相位偏移演算理論(Phase-Shifting algorithm)，進而提升頻域光學掃描系統的即時取像能力及穩定度。
本論文研究並比較傳統的相位偏移演算理論以及平行光柵對模組的群速延遲相位偏移演算理論在頻域光學斷層系統的取像分析，分別在單層與多層樣品架構，經由樣品模擬分析之後，此群速延遲相位偏移演算理論系統之效能及誤差度確實較優於傳統的相位偏移演算理論系統，較有利於提升頻域光學斷層系統影像解析的正確度。

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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