探索微米透鏡超解析顯微術之機制

Investigating the Mechanism of Superresolution of Dielectric Microspheres

李品儀(Pin-Yi Li)

指導教授 ： 朱士維

共同指導教授 ： 張之威(Chih-Wei Chang)

國立臺灣大學/理學院/應用物理研究所/碩士(2017年)

https://doi.org/10.6342/NTU201702093

摘要

超解析顯微技術(superresolution)常用來打破繞射極限，但缺點是掃描影像速度過慢、螢光分子壽命太短，以及繁複的樣品製備流程。近期有研究發現介電微米小球可以將波長尺度之下的資訊傳遞至遠場，也就是白光下就會有超解析現象，而我們也實驗證實用微米小球可以達到比λ/6.4更好的空間解析度。不過，介電微球產生超解析現象的機制仍有爭議，而其中兩種可能的解釋為回音壁模態(whispering gallery mode)和衰減波(evanescent wave)。

我們的實驗結果排除了這兩種機制造成超解析現象的可能性，並提出耦合同調超解析是提升解析度的主因。我們的實驗證據進一步指出，結合耦合同調超解析和微米小球的情況下，不論在金屬或非金屬的樣品上都可以顯著提升解析度。

關鍵字

漸逝波 ； 微米小球 ； 繞射極限

並列摘要

Superresolution techniques are widely-used approaches to overcome diffraction limit. However, those techniques encounter difficulties, such as sluggish scanning speeds, limited lifetime of fluorescent dyes, or sophisticated fabrication processes. Recently, it has been shown that dielectric microspheres can bring the sub-wavelength information to far-field, achieving superresolution by a white-light source. Indeed, we have also demonstrated that it can reach spatial resolution better than λ/6.4 using the microspheres.
However, the underlying mechanism of microsphere superresolution is still under debate. Two possible mechanisms are whispering gallery modes and evanescent waves. In this thesis, we experimentally exclude the two mechanisms be likely explanations. Instead, we propose and demonstrate coupling-induced coherent superresolution to be the mechanism for enhancement of resolution. We further show evidence that by combining the coupling-induced coherent superresolution and microsphere can drastically increase the resolution when imaging metallic and nonmetallic samples.

並列關鍵字

evanescent wave, microsphere ； superresolution ； superlens ； diffraction limit

參考文獻

[1] W. Coene, G. Janssen, M. O. de Beeck, and D. Van Dyck, “Phase retrieval through focus variation for ultra-resolution in field-emission transmission electron microscopy,” Phys. Rev. Lett., vol. 69, no. 26, p. 3743, 1992.

[2] A. Niemietz and L. Reimer, “Digital image processing of multiple detector signals in scanning electron microscopy,” Ultramicroscopy, vol. 16, no. 2, pp. 161–173, 1985.

[3] G. Binnig, C. F. Quate, and C. Gerber, “Atomic force microscope,” Phys. Rev. Lett., vol. 56, no. 9, p. 930, 1986.

[4] A. Ghatak, Optics. Boston: McGraw-Hill Higher Education, 2010.

[6] E. Betzig, J. Trautman, and others, “Near-field optics- Microscopy, spectroscopy, and surface modification beyond the diffraction limit,” Science (80-. )., vol. 257, no. 5067, pp. 189–195, 1992.