基于液晶热光效应的非电读出热探测技术研究
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摘要
红外热成像探测器由于其应用广泛而备受关注,而非制冷型探测器与制冷型探测器相比,具有体积小、成本低和可靠性高的优势。近些年来,随着红外探测成像技术的发展,现有的非制冷探测技术遇上了技术瓶颈,其中关键是缺乏高性能材料。克服这一困难的技术途径很多,如采用全新的信号产生和读出机制、寻找不同于常规的新材料等。
本文基于胆甾相液晶热光效应,设计了一种新型光学读出方式的红外探测成像系统,其核心部件为红外敏感装置,由装在红外液晶盒内的胆甾相液晶构成。以此光学系统为平台,本文重点研究了胆甾相液晶的旋光特性、红外液晶盒中红外吸收薄膜与取向薄膜的制备工艺。在胆甾相液晶旋光特性的研究方面,通过设计搭建测量光路,研究了温度变化速率、S811的含量、测量光路中起偏器与检偏器夹角θ对胆甾相液晶旋光特性的影响,并制备出了旋光特性符合本文成像要求的胆甾相液晶样品。在红外吸收薄膜制备过程中,选取ITO为红外吸收材料,采用磁控溅射法沉积薄膜,研究了制备工艺参数对薄膜厚度、光学特性及方阻特性的影响,获得了红外吸收率为58%的ITO薄膜的最佳制备工艺参数。在取向薄膜制备过程中,选取聚酰亚胺(PI)为取向材料,重点研究了PI浓度、匀胶转速、热处理时间与温度对取向薄膜厚度的影响,制备出了固化后膜厚为63nm的取向薄膜,并对其光学特性进行了研究。
通过对本课题的研究,设计出了一种实现光学读出红外探测成像的新方法,本光学读出系统具有无需制冷,无需金属导线连接,在探测器上不会产生附加热量等优点,这为液晶材料的应用与光学读出方式的红外探测成像技术提供了新的研究思路。
Much attention has been paid to thermal irradiation detectors for their wide applications. Compared with cooled detectors, uncooled thermal imaging devices have many advantages, such as small dimension, low cost, and superior reliability. In recent years, with the infrared detect imaging technology rapidly developing, uncooled detection technology meets the technical bottlenecks, and the key problem is lacking of high-performance materials. There are many ways to solve this problem, such as using the new way for the signal generation and reading, or looking for new materials.
Based on the optical rotation property of cholesteric liquid crystals(CLCs), an optical readout infrared detect imaging system is designed. The core of the system is the infrared sensitive device composed of the infrared liquid crystal box and CLCs. In this article, the optical rotation characteristic of CLCs with temperature changing, the production process of infrared absorption thin film, and orientation thin film in the infrared liquid crystal box are studied. In order to study the optical rotation characteristic of CLCs, a measuring optical path is designed. The impact of the rate of temperature change, S811 content, and the angle between the two polarizers on the optical rotation is studied, and the samples of CLCs that meet the imaging requirements are produced. In the production process of infrared liquid crystal box, the ITO prepared by RF magnetron sputtering is selected as the infrared absorption material. The impact of the process parameters on the thickness, optical properties and electrical properties of ITO thin film are also researched. The optimal technological parameters are obtained for ITO thin film with the infrared absorption of 58%. On the other hand, the orientation material is polyimide. Our study focuses are the impacts of the concentration of polyimide solution, the speed of spinning coater, temperature and time of thermal processing on the thickness of the orientation thin film. With a lot of experiments, the samples of PI thin film are obtained that the thickness is 63nm after curing, and the optical properties of the samples are also analyzed.
In this subject, a new method for optical readout infrared detection imaging is achieved. This optical readout system does not need the cooling device and metal wires, and it does not produce additional heat on the detector, so it provides a new idea for the application of liquid crystal material and the optical readout infrared detection imaging technology.
本文基于胆甾相液晶热光效应,设计了一种新型光学读出方式的红外探测成像系统,其核心部件为红外敏感装置,由装在红外液晶盒内的胆甾相液晶构成。以此光学系统为平台,本文重点研究了胆甾相液晶的旋光特性、红外液晶盒中红外吸收薄膜与取向薄膜的制备工艺。在胆甾相液晶旋光特性的研究方面,通过设计搭建测量光路,研究了温度变化速率、S811的含量、测量光路中起偏器与检偏器夹角θ对胆甾相液晶旋光特性的影响,并制备出了旋光特性符合本文成像要求的胆甾相液晶样品。在红外吸收薄膜制备过程中,选取ITO为红外吸收材料,采用磁控溅射法沉积薄膜,研究了制备工艺参数对薄膜厚度、光学特性及方阻特性的影响,获得了红外吸收率为58%的ITO薄膜的最佳制备工艺参数。在取向薄膜制备过程中,选取聚酰亚胺(PI)为取向材料,重点研究了PI浓度、匀胶转速、热处理时间与温度对取向薄膜厚度的影响,制备出了固化后膜厚为63nm的取向薄膜,并对其光学特性进行了研究。
通过对本课题的研究,设计出了一种实现光学读出红外探测成像的新方法,本光学读出系统具有无需制冷,无需金属导线连接,在探测器上不会产生附加热量等优点,这为液晶材料的应用与光学读出方式的红外探测成像技术提供了新的研究思路。
Much attention has been paid to thermal irradiation detectors for their wide applications. Compared with cooled detectors, uncooled thermal imaging devices have many advantages, such as small dimension, low cost, and superior reliability. In recent years, with the infrared detect imaging technology rapidly developing, uncooled detection technology meets the technical bottlenecks, and the key problem is lacking of high-performance materials. There are many ways to solve this problem, such as using the new way for the signal generation and reading, or looking for new materials.
Based on the optical rotation property of cholesteric liquid crystals(CLCs), an optical readout infrared detect imaging system is designed. The core of the system is the infrared sensitive device composed of the infrared liquid crystal box and CLCs. In this article, the optical rotation characteristic of CLCs with temperature changing, the production process of infrared absorption thin film, and orientation thin film in the infrared liquid crystal box are studied. In order to study the optical rotation characteristic of CLCs, a measuring optical path is designed. The impact of the rate of temperature change, S811 content, and the angle between the two polarizers on the optical rotation is studied, and the samples of CLCs that meet the imaging requirements are produced. In the production process of infrared liquid crystal box, the ITO prepared by RF magnetron sputtering is selected as the infrared absorption material. The impact of the process parameters on the thickness, optical properties and electrical properties of ITO thin film are also researched. The optimal technological parameters are obtained for ITO thin film with the infrared absorption of 58%. On the other hand, the orientation material is polyimide. Our study focuses are the impacts of the concentration of polyimide solution, the speed of spinning coater, temperature and time of thermal processing on the thickness of the orientation thin film. With a lot of experiments, the samples of PI thin film are obtained that the thickness is 63nm after curing, and the optical properties of the samples are also analyzed.
In this subject, a new method for optical readout infrared detection imaging is achieved. This optical readout system does not need the cooling device and metal wires, and it does not produce additional heat on the detector, so it provides a new idea for the application of liquid crystal material and the optical readout infrared detection imaging technology.
引文
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[2]张鹏.红外热成像系统作用距离的研究[D].南京：南京航空航天大学,2011.
[3]崔瑞青.红外成像预处理关键技术研究[D].西安：西北工业大学.2007.
[4]赵桂芳.红外焦平面阵列探测器关键技术研究[D].西安：西北工业大学,2007.
[5]任尚芬,程伟.能源效率、热电效应和纳米技术[J].评述,2007,36(9)：673-675.
[6]苗玉杰.医用红外测温仪及温度补偿技术的研究[D].秦皇岛：燕山大学,2005.
[7]郭哲颖.光学读出式室温红外成像系统[D].合肥：中国科学技术大学,2005.
[8]董凤良.基于MEMS的光学读出热成像技术的研究[D].合肥：中国科学技术大学,2007.
[9]熊志铭,张青川,陈大鹏,等.光学读出微梁阵列红外成像及性能分析[J].物理学报,2007,56(5)：2529-2535.
[10]张青川.光学读出红外成像研究进展[J].中国科学技术大学学报,2007,37(10)：1204-1208.
[11]Zhao Yang, Mao Mirryao, Roberto Horowitz, et al. Optomechanical uncooled infrared imaging system:Design, microfabrication, and performance [J]. Journal of Microelectr-omechanical Systems,2002,11 (2):136-146.
[12]Ishizuya T, Suzaki J, Akagawa K, et al. Optically readable biomaterial infrared detector [J]. Journal of Institute of Information and Television Engineers,2001,55(2):304-309.
[13]史永基.热色液晶红外传感器和摄像仪[J].测控技术,1999,18(3)：25-26.
[14]Shi Yongji. Liquid crystal infrared optics and applications [J]. SPIE,1990,1230:58-60.
[15]付学利.基于免疫算法的自适应小波变换在红外图像去噪中的研究[D].天津：河北工业大学,2009.
[16]田裕鹏.红外检测与诊断技术[M].北京：化学工业出版社,2006：1-13.
[17]张杰.红外热成像测温技术及其应用研究[D].成都：电子科技大学,2011.
[18]高思峰.飞行器红外特性分析与红外热成像系统作用距离的预估算方法[D].南京：南京航空航天大学,2007.
[19]韩军,刘钧.工程光学[M].西安：西安电子科技大学出版社,2007：403-404.
[20]Pascal Hubert, Pontus J gemalm, Claudio Oldano, et al. Optic models for short-pitch and chiral smectic liquid crystals [J]. Physical Review E,1998,58(3):3264-3272.
[21]李昌立,孙晶,蔡红星,等.胆甾相液晶的光学特性[J].液晶与显示,2002,17(3)：193-198.
[22]Ya Zhang, Changlong Cai, Xiao-ling Niu, et al. Study of infrared imaging system based on liquid-crystal thermo-optic effect [J]. Solid State Phenomena,2012,181-182:106-109.
[23]Changlong Cai, Ya Zhang, Xiao-ling Niu, et al. Research on non-electric readout infrared thermal imaging detection technology based on the liquid crystal [J]. Solid State Phenomena,2012,181-182:293-296.
[24]范志新.液晶器件工艺基础[M].北京：北京邮电大学出版社,2000：181-188.
[25]杜新语.增亮膜用双端丙烯酸酯类液晶化合物的合成与表征[D].济南：山东轻工业学院,2009.
[26]Nobuya Tamura, Seiji Takata. Thermal emissivity of semitransparent and opaque films of cholesteric liquid crystal [J]. Applied optics,1978,17(19):3051-3053.
[27]Wulf.A. Fluctuations in the low-temperature phase of a model cholesteric liquid crystal [J]. Physical review,1973,8(4):2017-2020.
[28]刘厚通.液晶旋光效应的研究[D].曲阜：曲阜师范大学,2005.
[29]唐韶坤,张磊,郑文杰,等.胆甾型液晶用于体温的精密测量[J].高分子材料科学与工程,2008,24(5)：128-130.
[30]Ryotaro Ozaki, Toshikazu Shinpo, Hiroshi Moritake. Improvement of orientation of planar cholesteric liquid crystal by rapid thermal processing [J]. Applied physics letters, 2008,92(16):3304-3306.
[31]白俊霞,郝伟,李霞.光折变液晶材料5CB的光谱分析[J].山西大同大学学报,2008,24(3)：19-20.
[32]马卫红,蔡长龙.磁控溅射制备ITO薄膜光电性能的研究[J].真空,2011,48(6)：18-20.
[33]马卫红,翟于嘉,蔡长龙.磁控溅射法制备镍热敏薄膜的工艺研究[J].西安工业大学学报,2011,31(5)：409-412.
[34]宋淑梅.多层结构透明导电氧化物薄膜的制备及特性研究[D].济南：山东大学,2010.
[35]王树林.ITO薄膜的制备及性能研究[D].武汉：武汉理工大学,2004.
[36]汪钢.磁控溅射法制备ITO薄膜的结构及光电性能研究[D].哈尔滨：哈尔滨理工大学,2009.
[37]周强.有机衬底上沉积禁带宽度可调的CdO透明导电薄膜[D].杭州：浙江大学,2006.
[38]黄东.基于氧化物薄膜的低阈值电压压敏电阻[D].杭州：浙江大学,2008.
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