Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/2605
標題: 多光束液晶繞射光學元件之研究
Study of Multi-beam Liquid Crystal Diffractive Optical Element
作者: 蔡智原
TSAI, CHIH-YUAH
關鍵字: multiple-beam;多光束;polarization-selective;optical pickup head;holographic optical element;diffractive optical element;liquid crystal;偏極光選擇性;光學讀寫頭;全像光學元件;繞射光學元件;液晶
出版社: 機械工程學系
摘要: 
本論文主要研究以液晶為介質材料,來製作全像型多光束光學讀寫頭中產生多道等光強讀取光束之多光束液晶繞射光學元件。我們採用Dammann所提出之二階相位型光柵設計方法來設計產生七道等光強光束,並且將此等光強光束光柵圖形蝕刻在鍍有ITO膜的玻璃基板上,當做多光束液晶繞射光學元件之一端電極。而在製作多光束液晶繞射光學元件時,我們分別使用間隙物及鍍製光阻層的方式來控制液晶之厚度,以達到最佳之繞射效率。
實驗結果證明使用間隙物與光阻層的方法均可以成功製作出多光束液晶繞射光學元件,而使用間隙物所製作之液晶元件在外加電壓的調配下,可以得到七道幾乎等光強的繞射光束。另外我們也實驗證明出液晶元件確實具有偏極化光選擇效果,並且液晶元件之響應速度也足夠用來應用於光學讀寫頭系統中,實現了多光束液晶繞射光學元件的目標。

This study investigates the feasibility of designing the multiple-beam liquid crystal diffractive optical element (LCDOE) for the use of the holographic multiple-beam optical pickup head. We adopted the design method of the binary phase grating proposed by Dammann for generating seven diffraction orders with equal intensity. The pattern of the multiple beam grating was etched on the ITO glass substrate to act as the electrodes for the LCDOE. In producing the LCDOE, we used not only the spacer but also coating a photoresist layer for controlling the liquid crystal thickness and getting the optimum diffraction efficiency.
The experimental results show that both methods of using spacer and photoresist are applicable for the device fabrication. The multiple-beam LCDOE that was produced by using spacer can effectively generating seven beams with equal intensity under applying a voltage. Besides, the polarization-selective effect for different polarization states was verified. The response time of this device is short enough for the application of an optical pickup head and the multiple-beam LCDOE is successfully realized.
URI: http://hdl.handle.net/11455/2605
Appears in Collections:機械工程學系所

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