雷射掃描式差動共軛焦顯微鏡之新穎設計與進階控制

A Novel Design and Advanced Control for Laser Scanning Differential Confocal Microscopy

劉韋志(Wei-Chih Liu)

指導教授 ： 傅立成

國立臺灣大學/電機資訊學院/電機工程學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201602058

摘要

在現今的工程領域中，雷射共軛焦顯微鏡是一種非常多用途的檢測工具。此種儀器能夠用來精確地獲得次微米級的結構或重建生物細胞的三維輪廓。然而，此種儀器仍然存在許多限制。尤其在垂直掃描速度方面，一直是學者們所關注的重大議題。此種限制使得人們無法快速且有效地獲得三維影像。因此，在本論文提出一種新型雷射掃描式差動共軛焦顯微鏡、並結合進階控制器來增進垂直掃描速度及精度。此種設計將使用兩種修改方法去確保所設計之系統的掃描速度及精確度能同時達到所預設之目標。
首先，為了減少掃描時間，本論文提出一種修正式的掃描方法、並應用於一自組式差動共軛焦顯微鏡。使用此種形式共軛焦顯微鏡的優點，可以大幅減少不必要的垂直掃描層數，因此，成像的掃描時間將被大大地減少。其次，由於壓電定位平台具有高精確及快速響應的優點，因此使用壓電裝置作為本研究之掃描致動器。然而，壓電的物理特性例如: 遲滯現象以及蠕變現象，將使掃描裝置產生不必要的非線性追蹤誤差，因此本論文使用適應性滑動模式控制方法來處理此上述所面臨之問題。此外由於垂直掃描器需追蹤一連續步階軌跡，所以本研究採用內部模型原理，設計出適用於此掃描軌跡特性的進階控制器，使系統的追蹤誤差值能夠最小化。所設計之新型掃描系統將可以大幅度地改善目前雷射共軛焦顯微鏡於垂直方向速度與精確度無法兼顧的問題。最後藉由一連串的實驗結果驗證，所開發之新型雷射掃描式差動共軛焦顯微鏡具有優異的掃描能力與影像可靠度。

關鍵字

雷射掃描式差動共軛焦顯微鏡 ； 壓電平台 ； 內部模型原理 ； 滑動模式控制 ； 適應性控制

並列摘要

Laser confocal microscopy (LCM) is a versatile instrument in the modern engineering fields. Such powerful tool can be used to accurately measure micro-fabricated structures or to reconstruct 3-D profile of the biological cell. However, there still exists vertical speed limitation in this inspection instrument such that people can’t quickly obtain a high-precision 3-D topography. In this work, a novel laser scanning differential confocal microscopy (LSDCM) combining with an advanced controller is proposed to simultaneously guarantee the vertical scan speed and scanning accuracy with two types of modifications.
First, in order to reduce the vertical scan time, a modified differential confocal microscopy is applied. With this type of microscopy, the small step multi-layer Z-axis scan could be removed, and thus the scanning time can be largely reduced. Second, the piezoelectric stage is employed as the scanning actuator due to its excellent accuracy and high bandwidth. Some inevitable problems such as hysteresis and creep in piezoelectric scanner can be effectively addressed by the adaptive sliding mode control (ASMC). In addition, since the reference signal of Z-axis stage is known a priori, the internal model principle (IMP) is integrated into the ASMC in order to ensure the tracking error is minimum. With the two aforementioned modifications, this measuring system can well tackle the issues of vertical scanning speed and high accuracy in the LCM field. The satisfactory experimental results show the performance and reliability of this proposed system.

並列關鍵字

Laser scanning difference confocal microscopy ； Piezoelectric scanner ； Internal model principle ； Sliding mode control ； Adaptive control

參考文獻

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