Multi-Mode Fresnel Lens Using Polymer-Stabilized Liquid Crystal

透鏡為一般光學系統中不可或缺的元件，然而一般傳統的光學透鏡，其結構體積過大，在往微小化發展上有了限制，因此本研究根據液晶之雙折射性質(birefringence)與其受電場影響而重新轉向之光電特性，在融合高分子穩固液晶技術(polymer dispersion)與電極之設計，設計出單一元件具多種模式之液晶菲涅耳透鏡(Fresnel lens)，因其體積僅來自於玻璃材料之厚度，因此元件可達成微小化及多種焦距之特性。 藉由純量繞射理論之模擬探討其相關繞射效率，同時以手機之定焦鏡頭組為模擬架構，利用光學設計軟體模擬探討不同模式下其成像之變化，實作部份則以新式之電極設計及單體RM257作為聚合之材料來達成三模式液晶菲涅耳透鏡。實驗中證明在不同模式下，屏幕上之繞射圖形皆會有明顯之變化；此外，輸入影像在不同模式之下也會產生不同之成像效果，藉由液晶調變之特性，元件亦可利用電壓調整其聚焦之特性。於本研究中我們成功地結合了不同菲涅耳電極圖形於一繞射光學元件中，達成多模式之可調變液晶透鏡。The lens is an indispensable component for a general optical system, but its large structure would have some restrictions on the development of reducing the device dimension. This study is based on two characteristics of liquid crystal (LC), which are the birefringence and the electro-optical activity of alignment by the electric field. We demonstrate the LC Fresnel lens with multi-modes by using the technologies of polymer stabilized liquid crystal (PSLC) and electrode pattern design. Moreover, owing to the dependence of glass thickness for the device size, the device of the whole module can be microminiaturized and the focal variation achieved. With the simulations by scalar diffraction theory, the diffraction efficiency of the device has been discussed. Then, we adopted the lens module of a cell phone with the fixed focal length as the simulation model and discussed the image changes from different diffraction modes with the aid of the optical design software. In fabrication, we demonstrated the monolithic liquid crystal Fresnel lens with triplex diffraction modes using the techniques of mixing LC and UV-curable monomer (RM257) as the device material and designing novel electrodes. The experiments show that the diffraction patterns projected on the screen can be switched under different diffraction modes. Besides, the input image will also produce different image formations corresponding to different diffraction modes. The focusing of the LC lens is tunable by adjusting the applied voltage. In this research, we successfully combine different types of Fresnel electrode pattern in a diffractive optical element and make the multi-mode LC lens possible.摘要.......................................................I Abstract..................................................II 致謝.....................................................III 目錄......................................................IV 圖目錄....................................................VI 表目錄....................................................IX 第一章 緒論................................................1 1.1背景與研究目的..........................................1 1.2文獻探討................................................2 1.3論文架構................................................6 第二章 相關原理............................................7 2.1 液晶光學原理...........................................7 2.1.1 液晶簡介.............................................7 2.1.2 液晶之分類...........................................7 2.1.3 液晶之光學特性......................................11 2.2 繞射理論..............................................17 2.3 菲涅耳透鏡原理........................................21 2.3.1 菲涅耳半波帶........................................21 2.3.2 菲涅耳波帶片........................................23 2.3.3 二元式菲涅耳透鏡....................................25 2.4 液晶透鏡原理..........................................27 第三章 多模式液晶菲涅耳透鏡之設計與分析...................31 3.1 多模式液晶菲涅耳透鏡之設計............................31 3.2 電場分析..............................................45 第四章 多模式液晶菲涅耳透鏡之製作.........................49 4.1 黃光微影製程..........................................49 4.2 液晶定向製程..........................................50 4.3 液晶封裝..............................................51 4.4 PSLC製程..............................................53 第五章 實驗與分析.........................................55 5.1樣品說明...............................................55 5.2 實驗架設..............................................57 5.2.1 光學系統實驗架構....................................57 5.2.2 三模式液晶透鏡......................................58 5.2.3 成像量測架構........................................64 第六章 結論與未來展望.....................................66 6.1 結論..................................................66 6.2 未來展望..............................................67 參考文獻..................................................68 中英對照表................................................7