光學低同調顯微技術之系統組建與系統研究

在此次的研究中, 我們建立一套整合光學同調斷層掃瞄技術與等倍望遠鏡式掃描系統所組成的平面掃描系統。利用光學同調斷層掃瞄技術裡的低同調光源特性，確定同調的區域；並結合等倍望遠鏡式掃描系統在完成的二維平面影像上區別出同調的影像。而望遠鏡式掃描系統可藉由數學上理論的推導驗證。系統參數設定的部份，縱向解析力可利用130毫安培的順向電流驅動超級發光二極體光源，使其達到8.50微米。另外，在步進馬達精確度方面，可利用互相關的分析方法（cross correlation）進行實驗的分析。藉由分析CCD所擷取兩光點的相對位移量，在設定步進馬達每步1微米的量測實驗中，每步移動的誤差範圍為0.02微米。同理，應用於掃瞄鏡組，橫向解析力可藉由0.006伏特的電壓驅動伺服馬達使掃瞄鏡轉動，造成光進入物鏡後在物鏡的焦平面上位移5微米。在折射率的鑑別方面，藉由使用不同折射率匹配液的量測，可量測到最小折射率的鑑別度為0.07。目前，我們建構的光學同調平面掃描系統可以完成二維平面影像的掃描，但無法進一步有效的區別影像中的同調區域。

關鍵字

光學童調斷層掃瞄技術；光學童調斷層顯微技術；掃瞄系統；同調長度

並列摘要

In this study, we established an en-face scanning system by integrating an optical coherence tomography (OCT) and a telescope-based scanning system. Using the characteristic of developed OCT, a low coherent light source, together with the coherent gate and a telescope-based scanning system, two-dimension coherent image can be identified. The design of telescope-based scanning system could be also verified by mathematical matrix deduction. As for the system performance, we applied 130 mA electrical current to drive superluminant diode (SLD) such that the axial resolution could reach to 8.50 μm. In addition, in an effort to estimate the precision of stepping motor the corresponding spot image for each step is captured using CCD; therefore, the precision with each step, that is, the distance between two consecutive spots, could be obtained using two-dimensional cross-correlation process. In the precision of stepping motor experiment that setting 1 μm per step, the error can be kept 0.02 μm. Similarly, the process could be also applied to estimate the transversal resolution of the scanning system. We found that it requires 0.6 mV to drive the scanning mirror so that 5 μm displacement at the focal plane of the objective could be obtained. Furthermore, while measuring the oil with different refractive index, the result shows that the visibility of refractive index difference that can be identified is 0.07. Presently, our instrument can accomplish two-dimensional image scan but it can’t be distinguished by the coherence gate.

並列關鍵字

optical coherence tomography ； optical coherence microscopy ； scanning system ； coherence length

參考文獻

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國際替代計量

光學低同調顯微技術之系統組建與系統研究

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