操作於近紅外光II-b波段之全自動化、廣域、高解析光學同調斷層顯微術研究與開發

Abstract

在此研究論文中，我們成功開發了一套操作於近紅外光II-b波段之掃頻式光學同調斷層顯微術(SS-OCM)系統，為一高解析、全自動化且廣域之成像技術。本套系統中，使用中心波長為1.69微米、頻寬為170 奈米，縱向掃描頻率為90 kHz的長波長掃頻光源可以在散射介質中提供更深的成像深度，且其靈敏度可達96.3 dB；透過結合光學同調斷層掃描和共軛焦顯微鏡，本套系統的橫向解析度可達到〜11.7微米，軸向解析度（半高全寬）可達到〜17.4 微米。此外，利用馬賽克鑲嵌式的掃描成像方式可以擴大系統成像範圍，以補償了由於樣本端中的高數值孔徑（NA）而導致的有限視野。而在此全自動SS-OCM系統中，包括物鏡切換，參考端中的平移台和樣本端中的三維電控平移台，都可以通過客製化圖形使用者介面(GUI)進行控制。我們的客製化GUI不僅可以自動化控制系統中的電控零件，還能及時成像和立即查看拼接完成後的馬賽克式OCM影像。為驗證本套SS-OCM的成像效能，我們針對膠帶，人類的手指和口腔粘膜進行了三維成像。在上述之OCM影像結果中，可以清楚地觀察到膠帶中的分層結構、人類手指中的指甲接縫、表皮、真皮以及人類口腔粘膜中的上皮、固有層等，而這些結果成功地證明了本套高解析度SS-OCM在生物醫學影像中的成像效能。此外，為了達到廣域的成像特性，我們利用馬賽克成像模式針對固化的鼠腦切片和新鮮的鼠腦進行成像及將其重建，不論是客製化GUI中即時查看拼接完成後的馬賽克OCM影像功能，或離線馬賽克影像拼接的演算法都證明了廣域SS-OCM的可行性。在未來的研究中，我們將致力於使廣域SS-OCM系統在進行馬賽克拼接演算法時更加自動化，且在即時查看拼接完成後的馬賽克OCM影像功能，和離線馬賽克影像拼接的演算法中將圖像融合應用於拼接圖像之間的邊界，在不降低解析度的情況下使其邊界平滑化，以達到更完善的高解析、全自動、廣域之SS-OCM系統。

In this thesis work, we have developed swept-source optical coherence microscopy (SS-OCM) system operating near-infrared II-b window with high-resolution, fully-automatic, and wide-field imaging characteristics. A long-wavelength swept source with a central wavelength at 1.69 μm, an optical bandwidth of 170 nm, and an A-scan rate of 90 kHz can provide a deeper imaging depth in the scattering medium with a detection sensitivity of 96.3 dB. With the combination of optical coherence tomography and confocal microscopy, this system can achieve ~11.7 μm in lateral and ~17.4 μm in axial resolution (full-width at half maximum, FWHM), respectively. In addition, a mosaicking scanning protocol and algorithm were utilized to enlarge the imaging range, compensating for the limited field of view (FOV) due to the high numerical aperture (NA) objective used in the sample arm. In this fully-automatic SS-OCM system, all the components, including objective switching, translation stage in the reference arm, and the three-dimensional motorized stage in the sample arm, can be controlled by the customized graphic user interface (GUI). The customized GUI not only can control those electric components but also can achieve real-time imaging and review the mosaic stitched data right after the data acquisition finished. To validate the well-developed SS-OCM’s imaging capability, we imaged a roll of Scotch tape, human finger, and human oral mucosa. In the OCM images, the layered structure in the Scotch tape, the nail junction, epidermis, dermis in the human finger, and the epithelium, lamina propria, etc., in the human oral mucosa can be observed clearly. These results successfully demonstrated the capability of the high-resolution SS-OCM in biomedical imaging. Besides, to perform the wide-field characteristic, we imaged a fixed mouse brain slide and a fresh mouse brain ex vivo using the mosaic data acquisition mode. Either the mosaic stitched data review in the customized GUI or the off-line stitching algorithm demonstrated the feasibility of the wide-field SS-OCM. In the future, we will devote to making the wide-field SS-OCM system more automatic with the mosaic stitching algorithm and apply the image fusion to the boundaries between mosaic images both in the data reviewing tool and the off-line stitching algorithm.