Optically and electrically controllable spatial filter in a polymer-stabilized liquid crystal film with a photoconductive layer

• Main Authors: Jia-Ming Ma, 馬佳銘
• Other Authors: Chia-Rong Lee
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/27723392972600970928

碩士 === 國立成功大學 === 光電科學與工程研究所 === 97 === This thesis is entitled “Optically- and electrically controllable spatial filter in a polymer-stabilized liquid crystal (PSLC) film with a photoconductive (PC) layer”. With the application of a dc voltage,charges with opposite electricity can accumulate on the interfaces between the cell substrates and the LCs to generate a screened field which may partially offset the applied field. Once the cell is irradiated with a pump beam, the conductivity of the PC can enlarge such that the internal surface charges can discharge to reduce the screen effect and thus the threshold voltage for Freedericksz transition can decrease. When the LCs is electrically or optically controlled to reorient,the transmission of the cell decreases because of the confinement of the polymer network induced LC to multi-domain By varying the applied dc voltage or incident pumped intensity, different spatial distributions of the different pattern of the target object can be selected for filtering by the single PSLC cell, such that various reconstructed images can be obtained. A simulation using Fourier analysis is developed, and its result are in agreement with experimental result. Additionally, the PSLC spatial filter can be used on the application of controllable edge enhancement.