液晶透鏡應用於2D/3D可切換且焦距可調變之內視鏡系統

Abstract

傳統的3D立體內視鏡是由兩組鏡頭與兩組感光元件構成，因此3D內視鏡相較於一般內視鏡的體積更大。我們開發出利用六角形液晶透鏡陣列元件搭配一組感光元件，構成基於積成影像的立體影像擷取系統。本研究的主要貢獻在於我們提出利用凸面環狀的電極產生拋物面狀分佈的電場，藉此縮短液晶透鏡的焦距長度至2.5公分以內，進而使內視鏡能夠拍攝近距離的物體；此外也能夠使液晶透鏡具有較好的相位變化分佈，以及較低的驅動電壓。雖然六角形液晶透鏡能夠提供2D/3D切換的功能，但是在2D模式下無法調整焦距，因此我們提出多功能液晶透鏡元件(MFLC-lens)應用於2D/3D立體內視鏡中，在2D模式或3D模式下都可以調整焦距，不需要透過任何機械式移動結構。為了達成液晶透鏡調整焦距的功能，我們提出一種新的雙層電極結構，並且在電極之間塗佈透明高電阻值材料。為了提升拍攝影像品質，我們使用數種不同偏振態元件，包括線性偏振片、圓偏振片和四分之一波板(Quarter Wave-plate)。進一步，我們利用澤爾尼克多項式(Zernike polynomials)模擬光波前變化，找出透鏡的像差並且加以修正。

Conventional 3D endoscopes consist of two lenses and two sensors, which enlarged the size of the instrument and have limitations imposed by stereo systems. We have successfully developed a hexagonal LC-lens array for capturing 3D images by using a single sensor using integral imaging. The significant finding from this study is that we propose convex-ring electrode to produces parabolic-like electric field distribution, thus lowering the focal length to less than 2.5 cm. which enables the endoscope to capture closer objects for medical applications, also better phase distribution and lower applying voltage. Because, the hexagonal LC lens is only switchable 2D/3D and not tunable in 2D mode we proposed a multi-functional liquid-crystal lens (MFLC-lens) for 2D and 3D switchable function. Importantly, this MFLC-lens can further modulate the focal length without mechanical movement in both 2D and 3D modes. To achieve multiple focal length lens functions, a novel structure with dual-layer electrode coated by a high resistive transparent film was developed. To enhance the quality of the taken image several polarized imaging techniques were investigated using linearly polarized, circularly polarized and quarter wave plate. Moreover, we simulated the wave-front employing Zernike polynomials to figure out the aberration in order to eliminate it.