探討頻域光同調斷層攝影術之干涉訊號特性

Study on the Characteristics of Interference Signals in Fourier-Domain Optical Coherence Tomography

鄭至翔(Chi-Hsiang Cheng)

指導教授 ： 許怡仁

中原大學/理學院/應用物理研究所/碩士(2007年)

https://doi.org/10.6840/cycu200700658

摘要

在本研究當中，我們建立一套頻域光同調斷層攝影系統，並探討干涉訊號的特性。我們利用兩組相移法移除干涉訊號中的鏡像雜訊與自相干訊號，以增加量測的深度範圍。系統中參考端與樣品端的色散不匹配情形經過補償後，可以讓影像的解析度獲得改善並且讓訊號的旁波降低。我們發展了一套利用高斯頻譜調整干涉訊號的演算法，可以增加系統的解析度與提升影像的對比。而在傳統上，由於光同調斷層攝影系統是將光源假設為平面波的形式進行理論的推導，但實際上光源其光束是以高斯光束的行為在行進，當考慮了高斯光學的影響，干涉訊號將與以平面波推導的結果不同。我們以樣品端光束為高斯光束進行理論推導，模擬與分析樣品端反射鏡在透鏡焦平面前後不同位置時的干涉訊號，並透過我們的系統進行實驗的驗證。

關鍵字

光同調斷層攝影術 ； 解析度 ； 相移

並列摘要

In this research, we set up a Fourier-domain optical coherence tomography system to study the characteristics of interference signals. In order to remove the autocorrelation terms and mirror image of the interference signals, we used the two-frame method that allows us to increase the depth range. The dispersion mismatch between the reference and sample arms in our system was compensated to improve the resolution and reduce the sidelobes in images. We also developed an algorithm to modulate the interference signal with Gaussian spectrum. By use of this method, the axial resolution of the system can be increased and the contrast of the image can be enhanced. Furthermore, the light beams propagating in an OCT system was conventionally assumed to be in the form of plane wave. However, the actual behavior of the light beams in an OCT system is more likely to be Gaussian beams. While considering of the effects of Gaussian optics, the interference signals of OCT systems will be different to that of plane waves. We deduce the theory of OCT with considering the light beam coming from the sample arm to be a Gaussian beam. We simulated and analyzed the interference signals with different sample mirror position. The results were demonstrated by experiments with our system.

並列關鍵字

optical coherence tomography ； phase shift ； resolution

參考文獻

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[19] 邱建偉,“高斯光學對於光同調斷層攝影術之影響,”中原大學應用物理研究所碩士論文 (2006)

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