利用3D列印製作之高分子分散型液晶光學開關

Abstract

本論文設計了兩種不同的結構做出兩種不同的光學開關，藉由施加電壓使開關有不同的通光度，並定義通光度高的亮態為開，通光度低的暗態為關。 在元件的製程方面，本研究結合了高分子分散型液晶(Polymer-dispersed liquid crystal，簡稱PDLC)與3D列印中的熔融沉積成型技術（Fused Deposition Modeling，簡稱FDM）完成該元件。PDLC在光學開關中扮演調變的角色，在未施加電壓時呈現乳白色的不透光狀態，在施加交流電壓後會使得液晶順著電場方向整齊排列，進而提升透光度。而本研究利用FDM技術3D列印出元件的結構主體，但直接列印出來的成品會有表面粗糙的問題，因此利用列印材料在高溫會融化的特性，熱壓結構表面使其平整化，在平整化表面後可以去除光線在3D列印表面的漫反射現象，進而提升透光度。 在光學開關的量測方面，本研究使用CMOS結合顯微鏡進行光開關影像的對焦與拍攝，接著利用Matlab將CMOS捕捉到的影像轉換成256種不同的色階繪製在不同電壓下灰階轉換的曲線，進而仔細觀察開關的亮暗特性。

In this paper, we design two optical switches of different structures. The transmittance of optical switch varies from different bias. We define the high transmittance state as the on-state, while the low transmittance state is the off-state. This research combined Polymer-Dispersed Liquid Crystal (PDLC) and Fused Deposition Modeling, which is one of the techniques of 3D printing, to finish the fabrication of the device. PDLC plays a role of tuning in the optical switch. Under 0 bias, PDLC appears to be opaque state of milky white. Under AC bias, liquid crystals arrange with the direction of the electric field and the transmittance arises. We use the FDM technique to 3D print the main structure of the device. However, the structure has the problem of surface roughness after printing. So we use the characteristic of the printing material, which melts under high temperature, to hot press the structure to flatten the surface. After flattening, we can remove the diffuse reflection of the 3D printing surface and rise the transmittance. In measurement part, we combine the CMOS and microscope to capture the image of the optical switch. Then use Matlab to transform the image into 256 different grayscale levels and draw the curve of different bias. So we can closely observe the transmittance characteristic of the optical switches.