繞射光學元件之多重聚焦光點的研究

本研究根據繞射光學元件的分光原理與多焦點聚焦特性，以石英為基片利用半導體製程技術製作出相位式繞射光柵，設計製作繞射光柵分光後在平面上形成多焦點的雷射光鉗系統。這系統由高功率雷射、繞射光柵、聚焦透鏡、3?m微顆粒乘載平台等元件所組成。首先，我們以Fraunhofer繞射原理與干涉理論推導繞射光柵所需之參數，再以OSLO軟體模擬聚焦透鏡光路，來優化微粒子抓取時之最小光斑，繞射光斑具有等距離的特性，因此可以有規律的抓取微顆粒(細胞)。以光學軟體OSLO對參數進行系統元件最佳化設計與研究後，再由本校共同實驗室半導體製程(ICP蝕刻機等)進一步製作出相位式繞射光柵。本研究更以電子顯微鏡，檢查光柵之最小填充係數與是否有缺失，做為製程參數改善依據。最後將所製作之繞射光學元件架設於光鉗系統以驗證本架構微粒子(細胞)抓取特性。本光學系統在四點繞射光斑(直徑10?m與15?m)驗證階段，理論和模擬值吻合，光斑間距也與理論值一致。量測後單點繞射光斑之功率約為總輸入功率之10%(遠大於周圍其他光斑)，因此產生的光鉗能量可以一次抓取多個微小顆粒，有別於傳統的來回掃描的方式，本系統更具效率與使用的方便性。

關鍵字

繞射光學元件；分光；多焦點；半導體製程；電子顯微鏡；相位式繞射光柵；聚焦透鏡

並列摘要

This project is base on wave-dividing and multi-focusing diffractive optical elements, it bases on quartz substrate to make phase-diffraction grating with semiconductor processing. Designing unitary laser wavelength of diffractive optical elements wave-dividing and multi-focusing can emerge the arbitrary planar optical system; this system is composed of phase-diffraction grating and near field lenses optical elements. First, wave-dividing element use Fraunhofer diffractive optical and interference theory to calculate the diffractive parameter, using OSLO can get least spot size of optimal design of near field lenses multi-focusing can focus to arbitrary planar of these two optical elements It can get least and equidistant diffractive spot size. Using ICP make the phase-diffraction grating when OSLO has simulated the multi-focusing. Electron microscopy can follow up the default of diffractive optical elements. We set up a optical system to test and verify the optical function that we designed. The diffraction spot diameter is come up to about 10um and 15um and four points around the diffraction spot of the power is much larger than the other spot, so do not worry about the laser to interfere small particles, so this study can enhance the optical tweezers system, the efficiency of small particles in the crawl.

並列關鍵字

diffractive optical elements ； wave-dividing ； multi-focusing ； semiconductor processing ； Electron microscopy ； phase-diffraction grating ； near field lenses

參考文獻

[1]黃鈞正、吳崇安、邱爾德， “光學嵌住之技術簡介” 物理雙月刊，22卷，五期，pp.477-484，(2000)。

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