Study of Spatial Filters Based on Liquid Crystal Devices and Their Applications

液晶空間濾波元件之研究與應用

林宗賢(Tsung-Hsien Lin) ； 傅永貴(Andy Ying-Guey Fuh)

《光學工程》 97期 (2007/03) Pp. 1-8

https://doi.org/10.30011/OE.200703.0001

摘要

利用調制或擷取影像的空間頻率來提升影像品質已成為現代重要的研究及應用課題。本論文主要探討利用各種液晶元件來做為空間濾波器，包括利用聚合物－液晶混合薄膜及參雜偶氮染料液晶薄膜做出可電控及可偏振調制的空間濾波元件。此外，更使用參雜偶氮染料之平面結構膽固醇液晶薄膜達成可同時分離高低頻之半反穿空間濾波器。如搭配多層不同的液晶薄膜，更可只提取某影像的特定頻率成份。因篇幅的關係，本文將重點放在膽固醇液晶之半反穿空間濾波器的研究。

關鍵字

液晶元件 ； 空間濾波器 ； 傅氏光學

並列摘要

The manipulation of spatial frequencies of two dimensional images in the Fourier optical processing is well studied and applied for uses in many areas, such as edge enhancement, character recognition, image correlation and more recently medical image processing. This dissertation demonstrates the feasibility of using liquid crystal films as real-time and controllable spatial filters. We use polymer-dispersed liquid crystal films and dye-doped liquid crystal films as electrically switchable and polarization controllable spatial filters in the Fourier optical signal process. Otherwise, we exploit the photoisomerization effect in azo-dye-doped cholesteric liquid crystal films as a transflective spatial filter. High-and low-pass images in the Fourier optical signal process can be simultaneously observed via reflected and transmitted signals, respectively.

並列關鍵字

Liquid Crystal Device ； Spatial Filter ； Fourier Optics