分光鏡式同步相移干涉術之研究

Research of Simultaneous Phase-Shifting Interferometry by Using Beam Splitters

柯坤呈(Kuen-Chen Ke)

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(2014年)

https://doi.org/10.6342/NTU.2014.10865

摘要

本研究設計一套即時同步相移干涉儀，藉由DPSS之532nm綠光雷射作為光源模組，再搭配線性偏極板、立體分光鏡、片狀分光鏡、偏極分光鏡等等光學元件作為分光模組，利用單一取像同時擷取四個不同相移量之干涉影像，並以相位移干涉技術為基礎架構出雷射干涉表面重建儀。
首先先將光源通過一線型偏光鏡制成一線偏極光，此線偏極光經過平板分光鏡後，以非偏極分光方式分成參考光與測物光，在參考臂與物件臂距離相等以及條件相當下，再將光源進行合光，合光之後在經過個別立體分光鏡後再經反光面竟將光源傳送至立體偏極分光鏡中進行分光，使其於感光耦合元件進行成像，其中個別感光耦合元件將分別擷取個別波段之干涉條紋。
由於本系統之設計將會使光源在經由立體分光鏡的一次合光以及經由立體偏極分光鏡所形成之二次合光後，再經由個別光學元件之鍍膜而產生相移偏差量，於個別感光耦合元件產生四個子干涉場，四個子干涉場分別將代表不同之相移量，並非傳統之90度之相差偏移，達到即時與同步擷取光源之優勢，其量測之標準差為11nm。

關鍵字

相移干涉術 ； 環境干擾 ； 即時同步相移干涉術 ； 同步取像

並列摘要

A development of simultaneous phase shifting interferometry(SPSI) is developed for nano-scale microscopic 3-D surface measurement and reconstruction. Conventional phase shifting interferometry is encountered by its undesired measurement instability caused by potential environment vibration. However, there are two problems in previous version. First part is the version we developed before is not the incident light in system is too close to Brewster’s angle which is let p wave intensity become to zero. Second part is the system is not easy to adjust because the light path is complex and taking too much time to adjust.
In order to follow the strengths and overcome the weaknesses , we propose a kind of simultaneous phase shifting interferometry using beam splitters and right angle prism. The reflective angle at beam splitter abgle is 45。. This strength can avoid to be close to Brewster’s angle. The structure we build is simple and easy to achieve good aligment. Right angle prism is configured along in the reference arm for creating an adequate optical phase difference (OPD) between the object and reference arms, so four step phase-shifting is achievable. In our experimental setup, the phase reconstruction based on four-step phase shifting principle is designed with four unique phase differences but not equal phase shifting. The phase shifting is depending the coating layer in beam spliter . To verify measurement accuracy and repeatability, the developed system was employed to measure mirror surface profiles. The experiment result shows that the method is proven to be capable of performing one-shot interferometric measurement and minimizing influences from environmental disturbances with measurement repeatability down to 17 nm or less.

並列關鍵字

phase shifting interferometry ； one-shot measurement ； optical inspection ； Nano-scale measurement

參考文獻

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