扭曲向列型液晶纯相位空间光调制器
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摘要
液晶空间光调制器(Liquid Crystal Spatial Light Modulator，LCSLM)是构成实时光学信息处理、光学相关和光学神经网络等系统的关键主动器件，在光学信息处理研究中发挥重要的作用并有着广泛的应用，其应用领域包括精密测量、三维显示、数字全息、激光波前整形以及光学信息加密系统。本文以此为出发点，介绍了液晶空间光调制器实现光学振幅、相位调制的原理，并利用商用投影显示液晶屏，改进设计其驱动控制电路来构成液晶空间光调制器，最后采用马赫-曾德(Mach-Zehnder)干涉仪来测量分析其相位调制特性。本文就是从以下几个方面来研究：
首先，本文从液晶材料的发现与研究现状出发，详细介绍了液晶材料的特性，讨论了液晶分子指向矢的概念，指出其空间分布的决定性因素。介绍了扭曲向列液晶盒(Twist Nematic Liquid Crystal Cell，TN-LCC)的结构及扭曲向列液晶的多种电光效应。在此基础上，利用琼斯矩阵从理论上分析了扭曲向列液晶的复振幅调制特性和输出光偏振特性。
根据商用液晶屏的电光调制曲线和其实现强度调制所利用的电压范围，我们提出在原驱动控制电路的基础上加入视频信号处理模块，以去掉原设计中为了实现强度显示目的而引入的直流偏置电压，这样使液晶屏工作在电光调制曲线中强度调制较小的一段驱动电压范围，从而实现纯相位调制。
在设计好系统驱动控制电路之后，本文通过实验测定了该空间光调制器系统的相位、强度调制特性。首先介绍了测量LCSLM相位调制特性时所用的光路图及干涉测量原理，并详细介绍了从采集到的干涉图中提取相位信息的过程。在测试过程中，根据光路的特点，对光路中的元件进行调节，使光路满足最佳干涉条件，并使液晶的相位调制最大。接着介绍测量LCSLM强度调制特性的光路图和具体过程。最后给出该空间光调制器系统相位调制和强度调制的结果。
Liquid crystal phase-only spatial light modulator plays an important role in optical information process, optical correlation and optical interconnections. It can be used in many fields, such as precision measurement, three-dimensional display, digital holography, laser wave front shaping and optical information encryption system. Hence, it is very important to research it. In this paper, firstly, the principle of phase modulation and intensity modulation is introduced. Then the driver circuit board of commercial liquid crystal display panel is modified and designed based on the reference design module. Lastly, the phase modulation characteristic of this LCSLM is investigated by the Mach-Zehnder interferometer. The main points of this thesis are as follows.
Based on the optical properties of the liquid crystal material and the structure of twist nematic liquid crystal cell, the term of molecules direction vector and the influential factors of its spatial distribution are introduced. Then the complex transmission and polarization properties of output light are analyzed by the Jones matrix.
According to the relationship between signal amplitude and transmittance, the reference driver circuit is modified and a video signal process module is added in order to get rid of the DC voltage which is beneficial for the purpose of intensity modulation. So the drive voltage range can be limited in the phase-only modulation area.
After the driver circuit board designed, a SLM system is built by liquid crystal display panel, driver circuit board, polarizer, analyzer and PC. Then the phase modulation characteristic of this LCSLM is investigated by the Mach-Zehnder interferometer and interferograms captured by CCD are treated in order to extract the phase modulation information. In addition, we should adjust the components to satisfy the interference terms perfectly. The experimental setup and method to measure intensity modulation property are also introduced. Lastly, the phase and intensity modulation property are given in charts.
首先，本文从液晶材料的发现与研究现状出发，详细介绍了液晶材料的特性，讨论了液晶分子指向矢的概念，指出其空间分布的决定性因素。介绍了扭曲向列液晶盒(Twist Nematic Liquid Crystal Cell，TN-LCC)的结构及扭曲向列液晶的多种电光效应。在此基础上，利用琼斯矩阵从理论上分析了扭曲向列液晶的复振幅调制特性和输出光偏振特性。
根据商用液晶屏的电光调制曲线和其实现强度调制所利用的电压范围，我们提出在原驱动控制电路的基础上加入视频信号处理模块，以去掉原设计中为了实现强度显示目的而引入的直流偏置电压，这样使液晶屏工作在电光调制曲线中强度调制较小的一段驱动电压范围，从而实现纯相位调制。
在设计好系统驱动控制电路之后，本文通过实验测定了该空间光调制器系统的相位、强度调制特性。首先介绍了测量LCSLM相位调制特性时所用的光路图及干涉测量原理，并详细介绍了从采集到的干涉图中提取相位信息的过程。在测试过程中，根据光路的特点，对光路中的元件进行调节，使光路满足最佳干涉条件，并使液晶的相位调制最大。接着介绍测量LCSLM强度调制特性的光路图和具体过程。最后给出该空间光调制器系统相位调制和强度调制的结果。
Liquid crystal phase-only spatial light modulator plays an important role in optical information process, optical correlation and optical interconnections. It can be used in many fields, such as precision measurement, three-dimensional display, digital holography, laser wave front shaping and optical information encryption system. Hence, it is very important to research it. In this paper, firstly, the principle of phase modulation and intensity modulation is introduced. Then the driver circuit board of commercial liquid crystal display panel is modified and designed based on the reference design module. Lastly, the phase modulation characteristic of this LCSLM is investigated by the Mach-Zehnder interferometer. The main points of this thesis are as follows.
Based on the optical properties of the liquid crystal material and the structure of twist nematic liquid crystal cell, the term of molecules direction vector and the influential factors of its spatial distribution are introduced. Then the complex transmission and polarization properties of output light are analyzed by the Jones matrix.
According to the relationship between signal amplitude and transmittance, the reference driver circuit is modified and a video signal process module is added in order to get rid of the DC voltage which is beneficial for the purpose of intensity modulation. So the drive voltage range can be limited in the phase-only modulation area.
After the driver circuit board designed, a SLM system is built by liquid crystal display panel, driver circuit board, polarizer, analyzer and PC. Then the phase modulation characteristic of this LCSLM is investigated by the Mach-Zehnder interferometer and interferograms captured by CCD are treated in order to extract the phase modulation information. In addition, we should adjust the components to satisfy the interference terms perfectly. The experimental setup and method to measure intensity modulation property are also introduced. Lastly, the phase and intensity modulation property are given in charts.
引文
[1] Gang. CH, Guofan. J, Minxian. Wu et al. Using liquid crystal spatial light modulators for realizing digital filters in an incoherent correlator. SPIE. 1998,3297: 98-105.
[2] T.H. Barnes. The application of phase-only filters to optical interconnects and pattern recognition. J. Mordern Opt. 1990,37:1849-1863.
[3] 胡文华，李修建，杨建坤等．光寻址空间光调制器控制系统的设计与实现．光学与光电技术．2007，5(2)：62-64．
[4] Thomas. H. Bares, Tomoaki Eiju, Kiyofumi Matusda et al. Phase-only modulation using a twisted nematic liquid crystal television. Applied Optics. 1989,28(22):4845-4852.
[5] 宋成禹．电寻址空间光调制技术的研究：(硕士学位论文)．长春：中国科学院长春光学精密机械与物理研究所，2002．
[6] 胡晓改，薛唯．液晶纯位相空间光调制器．激光与光电子学进展．2001，12(5)：35-42．
[7] 刘永军，宣丽，胡立发等．高精度纯相位液晶空间光调制器的研究．光学学报．2005，25(12)：1682-1686．
[8] 陈怀新，隋展，陈祯培等．液晶电视(LCTV)的光学调制特性及其应用．中国激光．2000，27(8)：741-745．
[9] C. Goreki, L. Orita, B. Trolard. Real-time pattern recognition by phase-mostly correlator using hybrid modulation properties of EPSON liquid crystal TV. Opt. Rev. 1996,3:171.
[10] D.A. Gregory. Real time pattern recognition using a modified liquid crystal televison in a coherent optical correlator. Applied Optics. 1986,25:467-469.
[11] J. L. Horner, P.D. Gianino. Phase-only matched filtering. Applied Optics. 1984,23:812.
[12] 陈怀新，隋展，陈祯培等．采用液晶空间光调制进行激光光束的空间整形．光学学报．2001，9：1107-1111．
[13] 陈怀新，魏宏刚，陈祯培等．采用液晶空间光调制器的可控性阵列菲涅尔波带片．光子学报．2001，30(5)：562-566．
[14] 王滨，余飞鸿．利用液晶光阀实现二值化联合变换相关器的研究．光学学报．1997，17(3)：325．
[15] P.S. Erbach, D.A. Gregory, J.B. Hanmmock. Phase-only joint-transform correlator analysis and experimental results. Applied Optics. 1996,35(17):3091.
[16] 黄献烈，赖虹凯．位相调制的实时联合变换相关器．光学学报．1997，17(4)：456．
[17] 康辉，苏恒．利用液晶光阀实现实时图像微分．中国激光．1994，21(8)：657．
[18] 高教波，张戊寅，张盛等．实时图像边缘增强空间光调制器．应用光学．1995，16(1)：30-34．
[19] N. Konforti, E. Marom, S.T. Wu. Phase-only modulation with twisted nematic liquid crystal spatial light modulation. Optics Letters. 1998,13(3):251-254.
[20] Kanghua Lu, Bahaa E. Theory and design of the liquid crystal TV as an optical spatial phase modulator. 1990,29(3):240-246.
[21] D.B. Taber, J.A. Davis. Optically controlled Fabry-Perot interferometer using a liquid crystal light valve. Applied Optics. 1990,29:2623-2631.
[22] J.L. Pezzaniti, R.A. Chipman. Phase-only modulation of a twisted nematic liquid -crystal TV by use of the eigenpolariztion states. Optics letters. 1993,18(18):1567-1569.
[23] Jeffrey A. Davis, Ignacio Moreno, Philbert Tsai. Polarization eigenstates for twisted nematic liquid crystal displays. Applied Optics. 1998,37(5):937-945.
[24] Ignacio Moreno, Jeffrey A. Davis. Transmission and phase measurement for polarization eigenvectors in twisted-nematic liquid crystal spatial light modulators. Opt. Eng. 1998,37(11): 3048-3052.
[25] J.A. Davis, Philbert Tsai. Transmission variation in liquid crystal light modulators caused by interference and diffraction effects. Opt. Eng. 1999,38(6):1015-1057.
[26] Makoto Yamauchi. Utilization of elliptically polarized light for phase-only modulation by twisted nematic liquid crystal spatial light modulations. SPIE. 2001,4296: 116-125.
[27] Makoto Yamauchi. Origin and characteristic of ambiguous properties in measuring physical parameters of twisted nematic liquid crystal spatial light modulators. Opt. Eng. 2002,41(5):1134-1140.
[28] Makoto Yamauchi. Jones-matrix models for twisted-nematic liquid-crystal devices. Applied Optics. 2005, 44(21): 4484-4493.
[29] 胡晓改．液晶纯位相空间光调制器：(博士学位论文)．北京：北京理工大学研究生院，2001．
[30] 刘国林．液晶型纯位相空间光调制器的研究：(硕士学位论文)．北京：北京理工研究生院，2000．
[31] T.L. Kelly, J. Munch. Wavelength dependence of twisted nematic liquid crystal phase modulators. Opt. Comm. 1998,156:252-258.
[32] 徐鹏．液晶空间光调制器光调制特性测量及其在光学图像处理中的应用研究：(硕士学位论文)．山东：山东大学研究生院，2005．
[33] 赵晓凤，李大海，陈祯培．利用径向剪切干涉法测量液晶空间光调制器的位相调制特性．四川大学学报．2002，39(4)：183-196．
[34] 任秀云，蔡春伟，国承山．横向剪切干涉法共路测量LCSLM的位相调制特性．光子学报．2007，36(5)：126-132．
[35] 李育林，傅晓理著．液晶空间光凋制器及其应用．国防工业出版社．1996．
[36] 叶必卿．液晶空间光调制器特性研究及在全息测量中的应用：(博士学位论文)．浙江：浙江大学研究生院，2006．
[37] 杨虹．TFT-LCD驱动技术的研究：(博士学位论文)．长春：中国科学院长春光学精密机械与物理研究所，2000．
[38] 张英华．头戴显示器驱动和控制电路的研究：(硕士学位论文)．重庆：重庆大学研究生院，2005．
[39] T. Yamaguchi, K. Hamano. Inteferometric method of measuring complex piezoelectric constants of crystals in a frequency range up to about 50kHz. Jpn. J. Appl. Phys. 1979, 18:927-932.
[40] A. Nesci, R. Dandliker, H. P. Herzig.Quantitative amplitude and phase measurement by use of a heterodyne scanning near-field optical microscope. Opt. Lett. 2001, 26:208-210.
[41] M. Takeda, H. Ina, S. Kobayashi. Fourier-transform method of fringe-pattern analysis for computer-based topography and interferometry. J. Opt. Soc. Am. 1982, 72:156-160.
[42] C. Roddier,F. Roddier. Interferogram analysis using Fourier transform techniques. Applied Optics. 1987,26:1668-1673.
[43] K. A. Goldberg, J. Bokor. Fourier-transform method of phase-shift determination. Applied Optics.2001,40:2886-2894.
[44] C.S Guo,Z.Y Rong,J. L He. Determination of global phase shifts between interferograms using energy minimum algorithm. Applied Optics. 2003, 42(32):6514-651.
[2] T.H. Barnes. The application of phase-only filters to optical interconnects and pattern recognition. J. Mordern Opt. 1990,37:1849-1863.
[3] 胡文华，李修建，杨建坤等．光寻址空间光调制器控制系统的设计与实现．光学与光电技术．2007，5(2)：62-64．
[4] Thomas. H. Bares, Tomoaki Eiju, Kiyofumi Matusda et al. Phase-only modulation using a twisted nematic liquid crystal television. Applied Optics. 1989,28(22):4845-4852.
[5] 宋成禹．电寻址空间光调制技术的研究：(硕士学位论文)．长春：中国科学院长春光学精密机械与物理研究所，2002．
[6] 胡晓改，薛唯．液晶纯位相空间光调制器．激光与光电子学进展．2001，12(5)：35-42．
[7] 刘永军，宣丽，胡立发等．高精度纯相位液晶空间光调制器的研究．光学学报．2005，25(12)：1682-1686．
[8] 陈怀新，隋展，陈祯培等．液晶电视(LCTV)的光学调制特性及其应用．中国激光．2000，27(8)：741-745．
[9] C. Goreki, L. Orita, B. Trolard. Real-time pattern recognition by phase-mostly correlator using hybrid modulation properties of EPSON liquid crystal TV. Opt. Rev. 1996,3:171.
[10] D.A. Gregory. Real time pattern recognition using a modified liquid crystal televison in a coherent optical correlator. Applied Optics. 1986,25:467-469.
[11] J. L. Horner, P.D. Gianino. Phase-only matched filtering. Applied Optics. 1984,23:812.
[12] 陈怀新，隋展，陈祯培等．采用液晶空间光调制进行激光光束的空间整形．光学学报．2001，9：1107-1111．
[13] 陈怀新，魏宏刚，陈祯培等．采用液晶空间光调制器的可控性阵列菲涅尔波带片．光子学报．2001，30(5)：562-566．
[14] 王滨，余飞鸿．利用液晶光阀实现二值化联合变换相关器的研究．光学学报．1997，17(3)：325．
[15] P.S. Erbach, D.A. Gregory, J.B. Hanmmock. Phase-only joint-transform correlator analysis and experimental results. Applied Optics. 1996,35(17):3091.
[16] 黄献烈，赖虹凯．位相调制的实时联合变换相关器．光学学报．1997，17(4)：456．
[17] 康辉，苏恒．利用液晶光阀实现实时图像微分．中国激光．1994，21(8)：657．
[18] 高教波，张戊寅，张盛等．实时图像边缘增强空间光调制器．应用光学．1995，16(1)：30-34．
[19] N. Konforti, E. Marom, S.T. Wu. Phase-only modulation with twisted nematic liquid crystal spatial light modulation. Optics Letters. 1998,13(3):251-254.
[20] Kanghua Lu, Bahaa E. Theory and design of the liquid crystal TV as an optical spatial phase modulator. 1990,29(3):240-246.
[21] D.B. Taber, J.A. Davis. Optically controlled Fabry-Perot interferometer using a liquid crystal light valve. Applied Optics. 1990,29:2623-2631.
[22] J.L. Pezzaniti, R.A. Chipman. Phase-only modulation of a twisted nematic liquid -crystal TV by use of the eigenpolariztion states. Optics letters. 1993,18(18):1567-1569.
[23] Jeffrey A. Davis, Ignacio Moreno, Philbert Tsai. Polarization eigenstates for twisted nematic liquid crystal displays. Applied Optics. 1998,37(5):937-945.
[24] Ignacio Moreno, Jeffrey A. Davis. Transmission and phase measurement for polarization eigenvectors in twisted-nematic liquid crystal spatial light modulators. Opt. Eng. 1998,37(11): 3048-3052.
[25] J.A. Davis, Philbert Tsai. Transmission variation in liquid crystal light modulators caused by interference and diffraction effects. Opt. Eng. 1999,38(6):1015-1057.
[26] Makoto Yamauchi. Utilization of elliptically polarized light for phase-only modulation by twisted nematic liquid crystal spatial light modulations. SPIE. 2001,4296: 116-125.
[27] Makoto Yamauchi. Origin and characteristic of ambiguous properties in measuring physical parameters of twisted nematic liquid crystal spatial light modulators. Opt. Eng. 2002,41(5):1134-1140.
[28] Makoto Yamauchi. Jones-matrix models for twisted-nematic liquid-crystal devices. Applied Optics. 2005, 44(21): 4484-4493.
[29] 胡晓改．液晶纯位相空间光调制器：(博士学位论文)．北京：北京理工大学研究生院，2001．
[30] 刘国林．液晶型纯位相空间光调制器的研究：(硕士学位论文)．北京：北京理工研究生院，2000．
[31] T.L. Kelly, J. Munch. Wavelength dependence of twisted nematic liquid crystal phase modulators. Opt. Comm. 1998,156:252-258.
[32] 徐鹏．液晶空间光调制器光调制特性测量及其在光学图像处理中的应用研究：(硕士学位论文)．山东：山东大学研究生院，2005．
[33] 赵晓凤，李大海，陈祯培．利用径向剪切干涉法测量液晶空间光调制器的位相调制特性．四川大学学报．2002，39(4)：183-196．
[34] 任秀云，蔡春伟，国承山．横向剪切干涉法共路测量LCSLM的位相调制特性．光子学报．2007，36(5)：126-132．
[35] 李育林，傅晓理著．液晶空间光凋制器及其应用．国防工业出版社．1996．
[36] 叶必卿．液晶空间光调制器特性研究及在全息测量中的应用：(博士学位论文)．浙江：浙江大学研究生院，2006．
[37] 杨虹．TFT-LCD驱动技术的研究：(博士学位论文)．长春：中国科学院长春光学精密机械与物理研究所，2000．
[38] 张英华．头戴显示器驱动和控制电路的研究：(硕士学位论文)．重庆：重庆大学研究生院，2005．
[39] T. Yamaguchi, K. Hamano. Inteferometric method of measuring complex piezoelectric constants of crystals in a frequency range up to about 50kHz. Jpn. J. Appl. Phys. 1979, 18:927-932.
[40] A. Nesci, R. Dandliker, H. P. Herzig.Quantitative amplitude and phase measurement by use of a heterodyne scanning near-field optical microscope. Opt. Lett. 2001, 26:208-210.
[41] M. Takeda, H. Ina, S. Kobayashi. Fourier-transform method of fringe-pattern analysis for computer-based topography and interferometry. J. Opt. Soc. Am. 1982, 72:156-160.
[42] C. Roddier,F. Roddier. Interferogram analysis using Fourier transform techniques. Applied Optics. 1987,26:1668-1673.
[43] K. A. Goldberg, J. Bokor. Fourier-transform method of phase-shift determination. Applied Optics.2001,40:2886-2894.
[44] C.S Guo,Z.Y Rong,J. L He. Determination of global phase shifts between interferograms using energy minimum algorithm. Applied Optics. 2003, 42(32):6514-651.