運用數位微鏡裝置縮小點擴散函數之研究

Research on Narrowing the Point Spread Function Using DMD

劉修文(Hsiu-Wen Liu)

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(2020年)

https://doi.org/10.6342/NTU202003763

摘要

隨著科技與工業技術發展，高科技產品如半導體、IC晶片製程奈米化，產品表面輪廓、特徵尺寸的量測精度需求亦隨之提升。在工業界線上自動化量測產業中，光學量測系統已被廣泛應用。然而傳統光學量測法如共焦顯微鏡、干涉量測術受繞射極限限制，橫向解析度約200奈米。為了超越繞射極限，科學家提出各種超解析技術，在提升解析度的研究上，超解析技術是未來重要的發展趨勢。
本研究結合超像素DMD方法與干涉技術，利用超像素DMD方法分別調制兩個光場的振幅與相位，經物鏡聚焦後得兩個點擴散函數，使點擴散函數干涉。其中調制光場將使破壞性干涉發生於點擴散函數外圍，縮小點擴散函數，提升光學解析度。與多數點擴散函數相關研究不同，除了調變入射光場振幅，本研究將同時調變光場的相位，並直接設計點擴散函數，經傅立葉轉換得到對應入射光場，而光場相位的調變提高了對應入射光場分布的自由度。本研究克服近場光學工作距離小，需要高精度控制的限制，也改善了部分遠場光學具有量測時間差、需在物品表面塗層的問題，同時運用了操作容易的DMD與可見光源，提出了新的超解析技術。
模擬流程已發展完整，從點擴散函數設計、入射光場計算與入射光場調制，最後驗證模擬結果以超像素DMD方法實踐的可行性。模擬結果在縮小點擴散函數的目標上以艾瑞盤第一暗圈大小為基準可達到改善18%的效果。
實驗系統已具備實現超像素DMD方法初步實驗裝置與光學系統構想，結合模擬結果與前期超像素DMD方法的實驗經驗，未來將以架設完整實驗裝置、驗證點擴散函數縮小的研究方法與模擬流程優化為發展目標。

關鍵字

點擴散函數 ； 超解析技術 ； 繞射極限 ； 超像素 ； 數位微鏡裝置

並列摘要

With the development of industrial technology, high-tech products such as semiconductors and IC chip manufacturing processes are nano-scaled, and the requirements for measurement accuracy of product surface and feature dimensions have also increased. In the automated inline measurement industry, optical measurement systems have been widely used. However, traditional optical measurement methods such as confocal microscopy and interferometer are limited by the diffraction limit, and the lateral resolution is about 200nm. In order to surpass the diffraction limit, scientists have proposed various super-resolution technologies. In the research of improving resolution, super-resolution technology is an important development trend in the future.
The research combines the super-pixel DMD method and interference technology, and uses the super-pixel DMD method to modulate both the amplitude and phase of the two light fields. After focusing by the objective lens, two point spread functions can be obtained and interfere. Modulating the light field will cause destructive interference to occur at the periphery of the point spread function, reduce the size of the point spread function, and improve the optical resolution. Different from most researches related to point spread function, in addition to modulating the amplitude of the incident light field, the phase of the light field will be simultaneously modulated in the research. The point spread function will be directly designed, and the corresponding incident light field will be obtained through Fourier transform. The additional modulated parameter of phase distribution improves the variation of the incident light field distribution. The method overcomes the limitations of the small working distance and the need for high-precision control in near-field optics. It also prevents the disadvantages of the measurement time difference and the requirement of coating on the sample surface in some far-field optics. At the same time, it uses easy-to-operate DMD and visible light sources.
The simulation process of the method has been fully developed, from the point spread function design, the incident light field calculation and the incident light field modulation, and finally the feasibility of the simulation results to be realized by the super-pixel DMD method is verified. The simulation results of narrowing the point spread function can achieve 18% improvement based on the size of the first dark circle of Airy disk.
The experimental system has the preliminary experimental device for realizing the super-pixel DMD method and the optical system design. In the future, the optimization method of the simulation process and a complete experimental system are expected to be set up to verify the research method.

並列關鍵字

Point spread function ； super resolution ； diffraction limit ； super pixel ； DMD

參考文獻

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