利用940nm超穎透鏡的瞳孔偵測

Abstract

為了運用光的物理性質，傳統透鏡往往需要多種透鏡組合而成，因此受限於鏡片厚重的困擾，而超穎透鏡則可以解決此困境。 它是利用電腦進行計算及模擬，結合半導體製程技術，製作出一種具有次波長尺寸的微型結構，其本身非常微小，在現有的材料上進行表面的加工，透過產生特定線寬的奈米柱排列，以改變入射光的物理性質，進而達成聚焦的效果來偵測瞳孔。 在我本篇論文中，運用製程技術將非晶矽作為超穎透鏡的材料製作於玻璃基板上。首先我使用電子束光刻(正光阻)將圖案呈現在材料上，畫出所需奈米結構的圖案，緊接著蒸鍍一層鎳金屬作為蝕刻的遮擋層，再經過lift-off的步驟去除光阻與其上方金屬，並保留圖案，最後再使用，感應耦合式的電漿離子蝕刻出非晶矽的奈米柱。 我將製作於透明基板上的超穎透鏡結合現有的光學感測元件，將瞳孔的影像透過超穎透鏡聚焦於光學感光元件上，並利用公開平台上的瞳孔偵測軟體，進行瞳孔偵測，為超穎透鏡應用於瞳孔偵測取得了階段性的成功，未來期待能將成果運用於更多領域上。

To regulate the physical properties of light, traditional lenses often require a combination of multiple lenses, resulting in bulkiness. However, metalens can overcome the limitations of conventional lenses. They are created using computational capabilities and software for optical simulations, and finally fabricated with semiconductor processing techniques. These metalens are composed of sub-wavelength-sized microstructures. By fabricating specific patterns of nanostructures on the surface of existing materials, they can manipulate the physical properties of light, and achieve focusing effects, such as for pupil detection. In this thesis, semiconductor fabrication techniques are employed to create metalenses consisting of amorphous silicon on a transparent glass substrate. First, I employed electron-beam lithography (positive resist) to define the necessary nanostructures on the material. Then, a thin layer of metal (nickel) was deposited as an etching protection layer, After the lift-off process, the resist and the metal will be removed, leaving only the pattern standing. Finally, inductively coupled plasma reactive ion etching (ICP-RIE) was used to etch. I fabricated metalens on transparent substrate and integrated it with existing optical sensing components, focusing the pupil's image onto the optical sensor through the metalens. Using open-source pupil detection software, I successfully detected the pupil, achieving a milestone in applying metalenses for pupil detection. In the future, I look forward to extending these results to other fields and applications.