【摘要】：向列相液晶具有雙折射特性與介電常數(shù)各向異性,可以通過(guò)較低的電場(chǎng)來(lái)控制其光學(xué)性能。由向列相液晶制作的液晶光柵具有重量輕、尺寸小、功耗低、壽命長(zhǎng)、成本低、驅(qū)動(dòng)電壓低等特點(diǎn),在平板顯示,空間光通信裝置,傳感器等領(lǐng)域有很大的應(yīng)用潛力。目前,液晶光柵應(yīng)用的一個(gè)缺點(diǎn)就是響應(yīng)速度慢,除此之外,在光束掃描、偏轉(zhuǎn)、控制等功能上都符合實(shí)用化的要求。本文設(shè)計(jì)了一種OCB液晶光柵結(jié)構(gòu),光柵由兩片ITO玻璃基板組成,一塊基板上用光刻技術(shù)制做出叉指電極,另一塊基板為連續(xù)電極,通過(guò)在兩塊基板之間施加電壓,使液晶分子發(fā)生周期性的排列,入射光透過(guò)液晶層后產(chǎn)生相位差發(fā)生衍射現(xiàn)象,形成液晶光柵。OCB(光學(xué)補(bǔ)償彎曲)模式是利用液晶分子在初始偏壓下維持在彎曲狀態(tài),當(dāng)加上驅(qū)動(dòng)電壓時(shí)可以快速的由彎曲變?yōu)榇怪睜顟B(tài),且能抑制液晶分子偏轉(zhuǎn)時(shí)產(chǎn)生的回流效應(yīng),與從平行狀態(tài)變?yōu)榇怪睜顟B(tài)相比,響應(yīng)時(shí)間顯著降低。文中用混合平行取向PI和垂直取向PI方式得到使液晶與基板成5～6度預(yù)傾角的條件,制作出低預(yù)傾角OCB液晶光柵樣品和平行液晶光柵樣品,研究了對(duì)響應(yīng)時(shí)間影響較大的因素液晶粘滯系數(shù),盒厚和低預(yù)傾角下的偏壓。對(duì)不同條件下的OCB液晶光柵和平行液晶光柵進(jìn)行研究,發(fā)現(xiàn)液晶的粘滯系數(shù)越小,響應(yīng)時(shí)間越短,盒厚越薄,響應(yīng)時(shí)間越短,初始偏壓越高,響應(yīng)速度越快。在相同條件下,OCB液晶光柵響應(yīng)速度明顯高于平行液晶光柵,響應(yīng)時(shí)間僅為平行光柵的三分之一。測(cè)量了不同盒厚條件下OCB液晶光柵和平行液晶光柵0級(jí),1級(jí)以及2級(jí)的衍射效率,隨著電壓的升高0級(jí)衍射效率下降,1級(jí)和2級(jí)衍射效率都是先上升后略有下降。OCB模式液晶光柵1級(jí)和2級(jí)的最高衍射效率都高于平行模式液晶光柵,其12μ m樣品1級(jí)最高衍射效率可以達(dá)到33%,隨著盒厚的降低,響應(yīng)速度提高,衍射效率下降,尚需進(jìn)一步優(yōu)化以得到高衍射效率的快速響應(yīng)樣本。
[Abstract]:Nematic liquid crystals have birefringence and anisotropy of dielectric constant, which can be controlled by low electric field. Liquid crystal gratings fabricated by nematic liquid crystal have the advantages of light weight, small size, low power consumption, long life, low cost and low driving voltage. It has great application potential in the fields of flat panel display, space optical communication device, sensor and so on. At present, one of the disadvantages of liquid crystal grating application is its slow response speed. In addition, it meets the practical requirements in beam scanning, deflection, control and other functions. In this paper, a structure of OCB liquid crystal grating is designed. The grating is composed of two ITO glass substrates. The cross finger electrode is fabricated by lithography on one substrate, and the other substrate is a continuous electrode, by applying voltage between the two substrates. The liquid crystal molecules are arranged periodically and the phase difference is diffracted when the incident light passes through the liquid crystal layer. The. OCB (optical compensation mode of liquid crystal grating is used to maintain the liquid crystal molecule in the bending state under the initial bias voltage. When the driving voltage is added, it can quickly change from bending to vertical state, and can restrain the reflux effect of liquid crystal molecule deflection. Compared with the parallel state to the vertical state, the response time is significantly reduced. In this paper, the conditions of predip angle between liquid crystal and substrate are obtained by mixing parallel orientation PI and vertically oriented PI. The low predip angle OCB grating sample and the parallel liquid crystal grating sample are fabricated. The factors affecting the response time, such as the viscosity coefficient of liquid crystal, the cell thickness and the bias voltage at low predip angle, are studied. The OCB and parallel liquid crystal gratings under different conditions are studied. It is found that the smaller the viscosity coefficient, the shorter the response time, the thinner the cell thickness, the shorter the response time, the higher the initial bias voltage and the faster the response speed. Under the same conditions, the response speed of the OCB liquid crystal grating is obviously higher than that of the parallel liquid crystal grating, and the response time is only 1/3 of that of the parallel liquid crystal grating. The diffraction efficiency of OCB liquid crystal grating and parallel liquid crystal grating of 0, 1 and 2 order are measured under different cell thickness. The diffraction efficiency of 0 order decreases with the increase of voltage. The first and second order diffraction efficiency of the OCB liquid crystal grating is higher than that of the parallel mode liquid crystal grating, and the maximum diffraction efficiency of the first order of the 12 渭 m sample can reach 330.The diffraction efficiency of the first order and the second order of the OCB mode liquid crystal grating are both higher than that of the parallel mode liquid crystal grating. With the decrease of the cell thickness, the response speed increases and the diffraction efficiency decreases. Further optimization is needed to obtain the fast response samples with high diffraction efficiency.
【學(xué)位授予單位】：大連海事大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：TH74

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相關(guān)期刊論文 前1條

1 任洪文,黃錫珉,王宗凱,馬凱;聚合物分散液晶(PDLC)光柵的制備及其光衍射特性[J];光散射學(xué)報(bào);1997年Z1期

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本文編號(hào)：2370217