使用雷射雕刻製作高分子分散型液晶九宮格固體光圈

Abstract

本研究使用了高分子分散型液晶(Polymer-Dispersed Liquid Crystal, PDLC)及雷射雕刻，利用PDLC之液晶分子會隨著電場轉動方向來調變元件，並運用雷射雕刻取代繁複的微影製程，成功開發了低成本、可重複使用之九宮格固體光圈。 在元件結構上，在氧化銦錫(Indium Tin Oxide, ITO)玻璃上使用雷射雕刻將電極圖樣化，並垂直堆疊，其間隙物(Spacer)厚度為16 μm，再滴入PDLC混合液並照射紫外光固化。在材料選擇上，採用液晶(E7)與高分子聚合物(NOA65)進行PDLC的混合，PDLC具有反應時間短、不須使用偏振片等優點。其混合液的比例選擇了E7與NOA65以重量百分濃度6 : 4混合，此比例具有81.48%的對比度及臨界電壓13.0 V，當未施加電壓時，有最低的穿透率，有利於光圈的遮光。 光圈元件製作完成後，利用3D列印製作外殼，以利放置於鏡頭之中，調變不同光圈大小進行拍攝，最後進行元件的特性量測與景深之量化。

This research is related to Polymer-Dispersed Liquid Crystal (PDLC) and laser engraving. Modulating PDLC with different voltage can result in various transmittance with respect to the input signal. In the meanwhile, laser engraving is a simpler fabrication process compared to the complicated optical lithography. By this way, we create the low-cost and reusable Tick-Tack-Toe-Patterned solid aperture. In terms of device structure, the electrode on the Indium Tin Oxide (ITO) glass is patterned by laser engraving, and stack up two glasses with the spacer thickness 16 μm. After fill the spacer between two glasses with the PDLC, cure it using UV light. Considering the options of the materials, the PDLC, the mixture of E7 and NOA65, has the advantages such as short reacting time, and no need for polarizer etc. The mixture weight ratio of the NOA65 and E7 is 6:4 respectively. The contrast ratio is 81.48% and threshold voltage is 13 V. When the voltage is not applied, there is the lowest transmittance, and is benefit of diaphragm blocking the light. After the diaphragm is finished, we design a black case to package the device by 3D printing, and it helps us put the device in the lens to capture the photos with different sizes of diaphragms. At last, we measure the properties of the device, and quantize the depth of field.