具大尺度孔徑之非機械式可調變固體光圈

Abstract

光圈是光學成像系統中重要的元件之一，利用光圈、快門、透鏡組與其他光學元件在系統中的相對位置，能有效調整影像上的特性，例如:景深、通光量、特殊效果之拍攝等。 至今許多文獻提出許多不同型式之可調光圈，其中大多為光學液體式以及電濕潤式之調變光圈，亦有利用微機電型式製作之微機械式光圈，然而很少有研究顯示能適用於智慧型手機鏡頭之可調變光圈，因其光圈需具備使用壽命長、低成本、高速製作穩定性、卓越的可調性以及良好的光學特性。 本研究論文提出之光圈具備低成本、結構簡易、元件輕薄、壽命長、非機械式光圈，其主要原理採用PDLC之電場效應使高分子孔洞內之液晶分子受電場影響而偏轉，此時形成透明通光區域，可視為一可調變光圈。 實驗結果顯示本論文提出之光圈直徑可調範圍為2.8 mm ~ 4.4 mm (g = 20 μm)，線性調變響應可達19.57 μm/V (g = 20 μm)，且經由不同製程參數可快速客製化光圈元件，此光圈元件預期能應用於智慧型手機攝影、可調光學衰減元件、快門以及運用於其他光學系統中。

An optical aperture is one of the important elements in optical systems, specifically used to control the depth of field (DOF), luminous flux, scattering light. Utilizing optical aperture, shutter, lens and other optical components, image quality will be improved by optical elements relative location in the optical system. Many literatures have been proposed about variable aperture, few literatures have been devoted to smartphone aperture due to the micro-tunable aperture characteristics for smartphone photography, including long operating life, low cost, high reconstruction steadiness, speedy manufacture, prominent tunability and robust optical properties. In this thesis, we demonstrate a low cost, simple structure, light weight, fine tuning, non-mechanical aperture. The proposed device consists of a Norland optical adhesive 65 (NOA65) plano-convex lens, conductive and transparent polymer coating (CTPC), polymer dispersed liquid crystal (PDLC) layer and ITO conductive layer. The operation principle of the device use induced electrical field driving PDLC layer by applied voltage. In this way, the PDLC layer would be induced to transparent channel as a light transmission aperture. As an experimental result, the diameter of the aperture could be tuned from 2.8 mm to 4.4 mm and the linear relation of voltage and aperture size was nearly 19.57 μm/V. The proposed optical aperture may have potential application in smartphone photography, variable optical attenuators, light shutters and other optical systems.