使光學像差及表面性質精準最佳化之創新線型彩色共焦顯微術之發展

Development of novel line-scanned chromatic confocal microscopy for measurement accuracy optimization by considering optical aberration and surface property

阮廷阮(Nguyen Dinh Nguyen)

指導教授 ： 陳亮嘉

國立臺灣大學/工學院/機械工程學研究所/碩士(2019年)

https://doi.org/10.6342/NTU201804390

摘要

在此篇論文中，作者提出線型掃描式彩色共焦顯微術之發展方法，在照明模組及光譜儀模組的最佳化設計下，得以應用於實現高軸向解析及低標準差。
照明模組包含兩個雙凸透鏡及一圓柱鏡，可以在共焦入瞳狹縫上產生長度為10mm的聚焦直線，且其均質性及效率可達到百分之九十。
光譜儀模組是基於Czerny-Turner組態設計，包含五個基本光學元件，例如狹縫、兩個球面鏡、繞射狹縫及一感光耦合元件。其完整設計成功達到粒子光譜的解析，而其解析能力與理論值僅有百分之九的差異。
一個合適的曲線擬合模型能產生趨近於一的適合度，而本篇論文採用Lorentzian model作為峰值搜尋演算法。其具備較高的效率且具有精準生成波長與樣品輪廓間之深度編碼曲線的能力，使得樣品的三維形貌得以被準確地重建。
以上所有的創新設計得以產生優於0.3µm的軸向解析度，而其實質不確定度在系統之校正及表現實驗中為0.032µm到0.0623µm。此外，實驗量測之標準階高塊顯示實驗值與實際值之高度差異僅有0.3%。
本篇論文旨在提出一系統之表現及效率最大化且由光學校準、機械設計之方式減少光學像差及機械誤差之系統。此外，每個模組對應的機械治具皆被設計及製造以使所有部件能被容易地組裝成為緊實的探頭，不僅能應用於實驗室，還能在產業界使用。

關鍵字

自動化光學檢測 ； 彩色共焦顯微術 ； 峰值搜尋演算法 ； 光學系統設計

並列摘要

In this study, a developed line-scanned chromatic confocal is proposed and implemented to better achieve a high axial resolution and a low standard deviation through optimal designs of illumination module and spectrometer module being consistent with an 8X chromatic objective.
Illumination module including four similar double convex lenses and one-cylinder lens aims to generate a 10 mm focal line on confocal entrance slit, and its uniformity and efficiency are approximately estimated at 90%.
Spectrometer module based on Czerny-Turner configuration consisting of five basic optical components such as slit, two spherical mirrors, diffraction grating and the complementary metal oxide semiconductor (CMOS) sensor, is realistically modeled to successfully accomplish a practical spectral resolution with a nearly difference of 9% compared to the theoretical one.
A suitable curve fitting model with production of fit goodness of nearly one, Lorentzian model, is well qualified for significantly enhancing efficiency of peak finding algorithm which acts a vital role in accurately forming depth encoding curve between focal wavelength and sample’s profile. From that curve, 3D profile of sample under test is rebuilt to reveal object surface’s characteristics.
All of these improvements result in the reliably estimated axial resolution of being better than 0.3 µm, the substantial uncertainty from 0.032 µm to 0.0623 µm through doing system’s alignment and performing experiment. Also, the experimentally measured profile of a standard step height sample exposes the almost slightly height difference of approximately 0.3% against the standard one.
In order to maximize system’s performance and effectively reduce its optical aberration and mechanical errors as a result of optical alignment, mechanical design of each module is proposed. Also, the mechanical housing design is produced so that finally all modules would be easily assembled to constitute a compact probe which can be applied not only in laboratory environment but also in industry.

並列關鍵字

Automated optical inspection ； Chromatic confocal microscopy ； Peak detection algorithm ； Optical system design

參考文獻

[1] Chen, L.-C., Chang, Y.-W., and Li,H.-W., "Full-field chromatic confocal surface profilometry employing digital micro-mirror device correspondence for minimizing lateral cross talks," Opt.Eng., vol. 51, no. 8, pp. 81507-81510, 2012.

[2] T. Wilson, "Chapter 1," in Confocal Microscopy, London, Academic Press, 1990, p. 1–60.

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[4] Pawley, J. B., Masters, B. R., Handbook of biological confocal microscopy, J. Biomed. Opt, vol. 13, 2008.

[5] Tanaami, T., Otsuki, S., Tomosada, N., Kosugi, Y., Shimizu, M., and Ishida, H., "High-speed 1-frame/ms scanning confocal microscope with a microlens and Nipkow disks," Appl. Opt., vol. 41, no. 22, pp. 4704-4708, 2002.