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2022年  15卷  第1期

综述
铌酸锂薄膜调制器的研究进展
刘海锋, 郭宏杰, 谭满清, 李智勇
2022, 15(1): 1-13. doi: 10.37188/CO.2021-0115
摘要:
铌酸锂薄膜调制器具有体积小、带宽高、半波电压低的优点,在光纤通讯和光纤传感领域具有重要应用价值,是近年来的研究热点。本文梳理了铌酸锂薄膜调制器的波导结构、耦合结构、电极结构的研究进展,总结了LN薄膜波导的制备工艺,并深入分析了不同结构调制器的性能。基于SOI和LNOI结构,薄膜调制器实现了VπL<2 V∙cm,双锥形耦合方案实现了耦合损耗<0.5 dB/facet,行波电极结构实现了调制带宽>100 GHz。铌酸锂薄膜调制器的性能在大多数方面优于目前商用铌酸锂调制器,随着波导工艺进一步提升,将成为铌酸锂调制器的热门方案。最后对铌酸锂薄膜调制器的发展趋势和应用前景进行了展望。
原创文章
二元计算全息法产生复杂无衍射光束
杨婧羽, 任志君, 黄文俊, 许富洋
2022, 15(1): 14-21. doi: 10.37188/CO.2021-0061
摘要:
无衍射光束是一种能在自由空间稳定传输的光束。近来,一类具有复杂光学形态的无衍射光束被引入,比如马蒂厄光束、抛物光束、非对称贝塞尔光束等。为了产生具有复杂结构的无衍射光束,需要对光波进行复振幅调制,即同时调制光波的振幅和相位。但目前的商用光学调制元件只能调制光波的振幅或相位。本文基于二元计算全息法,编码二维复透过率函数分布,构建了具有复振幅调制功能的二元实振幅非负计算全息图。利用实验室自主研发的投影成像光刻系统,对银盐干板进行曝光处理,经显影、定影处理,将其加工为相应的振幅掩模板,用来产生精确的具有复杂结构的无衍射光束。以无衍射马蒂厄光束为例,采用罗曼型迂回相位编码方法,在全息图每个抽样单元内开一个矩形通光孔径,通过改变通光孔径的面积来对复值光波的振幅进行编码,通过改变通光孔径中心偏离抽样单元中心的距离,来对复值光波的相位进行编码。最终构建了两种产生马蒂厄光束的典型二元实振幅计算全息图,其像素数高达28000 pixel×28000 pixel。之后利用加工好的振幅掩模板,准确、方便、高效地产生了椭圆系数q=10,拓扑荷数m=0与m=1的第一种偶型马蒂厄光束,其他类型的马蒂厄光束可相应产生,这是一种光束形态多样、光束结构复杂的无衍射光束。实验结果证实,采用罗曼型迂回相位编码方法产生具有复杂结构的无衍射光束,有效避免了实验过程中分离的相位调制元件和振幅调制元件之间的对准误差,二元计算全息编码法是一种能用来调控产生复杂结构无衍射光束的新途径。
柔性复合薄膜成形极限曲线的视觉测定方法
陈仁虹, 梁晋, 叶美图, 任茂栋, 张继耀
2022, 15(1): 22-33. doi: 10.37188/CO.2021-0101
摘要:
针对柔性复合薄膜成形试验中极限应变难以测量的问题,提出一种基于双目立体视觉结合数字图像相关法的测量方法。首先对于薄膜材料成形过程中产生大变形或裂纹时图像难以匹配的问题,根据系列图像相邻状态变形的连续性,提出了一种图像匹配基准自适应更新的弱相关分步匹配方法;然后根据薄膜材料表面应变分布不同于钢制件的特性,提出了一种构建应变场截线来拟合薄膜材料的极限应变曲线的方法。专门组建视觉测定的软、硬件系统,通过Q235钢试件进行极限应变曲线测量并与坐标网格方法进行对比,材料极限应变精度能够提高0.02%,证明了本文方法的可行性和精确性。用7组PET/Nylon/Al foil/PP材料制备成的柔性复合薄膜试件进行实测,此方法及系统成功地完成了柔性复合薄膜材料的成形极限曲线测定。对比实验和实际测试证明,本文方法能够快速、准确地测量柔性复合薄膜材料在整个成形过程中的表面应变分布,与传统的坐标网格方法相比具有明显的优势,为测定薄膜材料的成形极限应变曲线提供了一种高可靠性、高精度的手段。
结合光源分割和线性图像深度估计的夜间图像去雾
吕建威, 钱锋, 韩昊男, 张葆
2022, 15(1): 34-44. doi: 10.37188/CO.2021-0114
摘要:
夜间有雾图像通常具有对比度低、光照不均匀、颜色偏移以及噪声较多等现象,这些退化现象使得夜间图像去雾具有极大的挑战性。针对夜间图像存在的退化问题,本文提出了一种能够在夜间图像中有效去雾并提高图像质量的方法。首先,将图像分解成光晕层和有雾层,并对有雾层进行颜色校正。其次,通过一种新提出的带有伽马变换的图像光源分割方法来分割光源,并设置分割阈值作为像素点属于光源区域的概率值。然后,将得到的概率值与最大反射先验相结合来估计光源和非光源区域的大气光值。最后,根据图像深度与亮度、饱和度以及梯度之间的关系建立线性模型,进一步估计透射率的值。实验得到的分割阈值为0.07,线性深度估计参数分别为1.0267、−0.5966、0.6735、0.004135。实验结果表明本文方法在夜间图像去雾、消除光晕、减少噪声,以及提高可视度方面取得良好的效果。
基于透镜阵列的三维姿态角度测量
杜明鑫, 闫钰锋, 张燃, 才存良, 于信, 白素平, 于洋
2022, 15(1): 45-55. doi: 10.37188/CO.2021-0129
摘要:
三维姿态角的精确测量在航空、航天、国防等领域应用广泛,为方便准确地实现三维姿态角的测量,本文设计了一种基于透镜阵列的测量系统,并建立了微小三维姿态角测量分析模型。系统中,准直平行光束通过4个排列成金字塔形的阵列透镜,在CCD上形成规则分布的阵列光斑。通过分析CCD成像光斑间的距离、透镜阵列上相邻孔径之间的距离以及透镜阵列与CCD之间的倾斜角,可以得到光束相对于接收系统俯仰角和偏摆角,利用阵列光斑连线相对水平或垂直面的夹角,可同时得到绕Z轴的滚转角。通过与高精度自准直仪测量结果进行比较,证明所提方法的测量精度可以达到RMS≤0.1″,表明该方法能够实现三维姿态角的测量。
基于等效矢量模型的双光楔逆解算法研究
冯建鑫, 王强, 王雅雷, 胥彪
2022, 15(1): 56-64. doi: 10.37188/CO.2021-0117
摘要:
为了进一步提高双光楔结构中反解算法的计算精度、减少计算时间,本文将正演迭代法与光楔等效矢量模型相结合,提出等效矢量迭代法。首先,根据光楔对光线的偏转作用建立光楔等效矢量模型。接着,利用矢量叠加的方法求解双光楔出射光线的矢量坐标。然后,将等效矢量模型代入双光楔两步逆解算法中进行计算,求解双光楔旋转角度的近似值。最后,利用正演迭代、逐步逼近的思想,提出等效矢量迭代逆解算法,并计算得到双光楔的旋转角度。实验结果表明:该算法的计算精度达到10 μm级别,计算时间在0.1 ms以内。该算法能有效提高计算精度、降低计算时间,在高精度光束指向领域具有广泛的应用前景。
基于一种透镜材料的宽谱段紫外成像仪光学设计
李寒霜, 李博, 李昊晨, 林冠宇
2022, 15(1): 65-71. doi: 10.37188/CO.2021-0127
摘要:
紫外探测技术已广泛应用于人类生产生活的各个方面,宽谱段紫外成像仪系统的研究具有重要意义。本文通过推导色差理论公式,提出了单一透镜材料的宽谱段紫外成像仪光学系统色差校正方案。结合高灵敏度大动态紫外成像探测器的性能指标要求,设计了仅一种透镜材料且所有透镜均为球面的210~400 nm宽谱段紫外成像仪光学系统,并运用光学设计软件CODE V进行系统优化及像质评价。结果表明:在奈奎斯特频率40 lp/mm下,全视场全波段系统的调制传递函数优于0.6,系统点列图RMS<7.8 μm,具有良好的成像质量。该系统不含非球面等光学元件,不仅易于加工装调,而且降低了研制成本,该方法将为宽谱段紫外成像光谱仪的设计奠定技术基础。
制冷型长波红外光学系统设计
单秋莎, 谢梅林, 刘朝晖, 陈荣利, 段晶, 刘凯, 姜凯, 周亮, 闫佩佩
2022, 15(1): 72-78. doi: 10.37188/CO.2021-0116
摘要:
针对640×512长波红外制冷型探测器,设计了一种制冷型长波红外光学系统,用于对目标的红外跟踪探测。该光学系统采用二次成像结构以达到100%冷光阑效率,采用锗和硫化锌玻璃材料相结合,实现了像差校正和消色差设计,通过引入高次非球面,很好地校正了系统的高级像差,简化了系统结构。光学系统由6个镜片构成,焦距为400 mm,工作波段为7.7~9.3 μm,视场角为1.37°×1.10°,F数为2。设计结果表明:在空间频率33 lp/mm处,轴外视场MTF>0.24,接近衍射极限,具有较高的成像品质。在−35~+55 ℃工作温度范围内,通过内置调焦镜调焦来保证高温、低温环境下的成像质量,可用于宽温度范围内的红外跟踪探测。
Longitudinal chromatic aberration compensation method for dual-wavelength retinal imaging adaptive optics systems
ZHU Qin-yu, HAN Guo-qing, PENG Jian-tao, RAO Qi-long, SHEN Yi-li, CHEN Mei-rui, SUN Hui-juan, MAO Hong-min, XU Guo-ding, CAO Zhao-liang, XUAN Li
2022, 15(1): 79-89. doi: 10.37188/CO.EN.2021-0009
摘要:
Dual-wavelength retinal imaging adaptive optics systems are suitable for high contrast and resolution imaging of retinal capillaries. The compensation of the Longitudinal Chromatic Aberrations (LCAs) in dual-wavelength adaptive systems is researched. The LCA is measured, the measured wavefronts are analyzed, and the arbitrary wavefront LCA compensation method is given. An adaptive correction experiment is carried out and the experimental results indicate that the root mean square error of the wavefront is reduced to 0.16 λ (λ=589 nm) and the retinal capillary resolution is improved to 6 μm. This work may be used for the clinical applications of retinal imaging.
Calibration of single optical wedge compensation test system error by computer generation hologram
CAI Zhi-hua, WANG Xiao-kun, HU Hai-xiang, CHENG Qiang, WANG Ruo-qiu, ZHANG Hai-dong
2022, 15(1): 90-100. doi: 10.37188/CO.EN.2021-0004
摘要:
As a testing method for large convex aspheric surface, the single optical wedge compensation test has good applicability, robustness and flexibility. However, various errors are coupled with one another during the test process and these errors are difficult to decouple. This affects the accuracy and reliability of the tests. To address this, a method is developed to calibrate the system error of single optical wedge test paths using a Computer Generation Hologram (CGH). We first analysed the source of system error in the optical path of a single optical wedge compensation test as well as the feasibility of using CGH for the calibration of an optical wedge compensation test system. In combination with engineering examples, a CGH was designed for optical wedge compensators with a diameter of 150 mm. Based on the analysis results, the calibration accuracy of the CGH was 1.98 nm RMS, and after calibration the test accuracy of single wedge compensation was 3.43 nm RMS, thereby meeting the high-precision test requirements of large convex aspheric mirrors. This shows that CGH can accurately calibrate the pose of single optical wedge compensators and the test system errors of optical paths. Thus we address the problems affecting error decoupling in test optical paths, and improve the accuracy and reliability of the single optical wedge compensation method. Meanwhile, using CGH calibration, the system errors of the test optical paths, Tap#2 and Tap#3, were 0.023 and 0.011 λ RMS, respectively.
High-sensitivity surface plasmon resonance sensor based on the ten-fold eccentric core quasi-D-shaped photonic quasi-crystal fiber coated with indium tin oxide
LIU Qiang, JIANG Yu, HU Chun-jie, LU Wen-shu, SUN Yu-dan, LIU Chao, LV Jing-wei, ZHAO Jin, TAI Sheng-nan, YI Zao, CHU Paul K
2022, 15(1): 101-110. doi: 10.37188/CO.EN.2021-0006
摘要:
A high-sensitivity Surface Plasmon Resonance (SPR) sensor comprising of an eccentric core ten-fold Photonic Quasi-crystal Fiber (PQF) with a D-shaped structure and partially coated with Indium Tin Oxide (ITO) is designed and numerically analyzed. The eccentric core D-shaped structure makes the analysis of liquids more convenient and also strengthens the coupling between the core mode and Surface Plasmon  Polariton (SPP) mode to improve the sensing sensitivity. The characteristics of the sensor are investigated by the Finite Element Method (FEM). The wavelength sensitivity increases with increasing Refractive Indexes (RIs) and the maximum wavelength sensitivity and resolution are 60000 nm/RIU and 1.67×10−6 RIU, respectively. The sensor delivers excellent performance and has large potential applications in the measurement of liquid refractive indexes.
Experimental investigation on propagation characteristics of vortex beams in underwater turbulence with different salinity
LU Teng-fei, LIU Yong-xin, WU Zhi-jun
2022, 15(1): 111-118. doi: 10.37188/CO.EN.2021-0001
摘要:
It is very important to study the propagation characteristics of light beams in ocean turbulence. In order to get closer to the actual situation, we build a device which can control both the salinity and the intensity of underwater turbulence to study the propagation characteristics of vortex beams and a Gaussian beam in underwater turbulence. The results show that compared with the underwater turbulence without sea salt, the light spot will be more diffuse and the light intensity will be weaker in the underwater turbulence with sea salt. When the topological charge m is 2, the scintillation index of the vortex beam in the underwater turbulence with salinity of 4.35‰ is larger than that in the underwater turbulence with salinity of 2.42‰, no matter it is strong turbulence or weak turbulence. When the vortex beam with m=2 propagates to the same distance, the scintillation index increases with the increment of the salinity and the intensity of underwater turbulence. Under different salinity conditions, the radial scintillation index of the vortex beam with m=2 decreases firstly and then increases with the increase of the radial distance. In addition, we set up another experimental device which can transmit a longer distance. The scintillation index of the vortex beam with m=2 is much higher than that of the Gaussian beam in the underwater turbulence within 20 m propagation distance, and the scintillation indices of both the vortex beam with m=2 and the Gaussian beam increase with the increase of the propagation distance.
Fabrication of an ultra-narrow band-pass filter with 60 pm bandwidth in green light band
WANG Kai-xuan, CHEN Gang, LIU Ding-quan, MA Chong, ZHANG Qiu-yu
2022, 15(1): 119-131. doi: 10.37188/CO.2021-0092
摘要:
Owing to the strong penetrating ability in the atmosphere, 532 nm-wavelength green laser has wide applications including free-space optical communications and laser three-dimensional mapping. A spectral filter, with a half-power bandwidth of less than 100 pm, is an important optical element to suppress the interference of background light. Therefore, an ultra-narrow band-pass filter based on optical interference film is designed and fabricated in this paper. The high and low refractive index film are made of tantalum pentoxide (Ta2O5) and silicon dioxide (SiO2), respectively. The designed optical thin films are deposited on a fused quartz substrate by double-ion-beam sputtering deposition method. The transmission spectra of the filters are measured by a tunable laser and a power meter. The half-power bandwidths of the filters are (60±2) pm, and the transmittance reaches 62.6%.
Illustrating the Helmholtz-Kohlrausch effect of quantum dots enhanced LCD through a comparative study
JI Hong-lei, CHENG Shang-jun, LI Peng-fei, ZHANG Yan, GE Zi-yi, ZHONG Hai-zheng
2022, 15(1): 132-143. doi: 10.37188/CO.2021-0058
摘要:
Helmholtz-Kohlrausch effect (H-K effect) describes the influence of color purity on the perceived brightness of a colored object. Quantum dots (QD) based backlights can enhance the color quality of Liquid Crystal Display (LCD) with improved perceived brightness due to the well-known H-K effect. However, the H-K effect of QD embedded TVs (also known as QLED TV) has not been fully demonstrated. In this paper, we investigated the H-K effect of QLED TVs through a comparative study between QLED backlights and YAG-LED backlights. By comparing the viewers’ experimental results with the Kaiser and Nayatani model, we demonstrate that a QLED TV shows significant H-K effect. To achieve the same perceived brightness with YAG-LED TV, the physical brightness of QLED TV was greatly decreased to 75% for pure red, 86% for pure green, and 74%-88% for bright colorful images. Moreover, QLED TVs are strongly preferred over YAG-LED TVs even when both QLED TV and YAG-LED TV show the same perceived brightness. The results imply the bright future of QLED TVs toward healthly displays.
Enhancing the fluorescence emission by flexible metal-dielectric-metal structures
CAO Wen-jing, SUN Li-ze-tong, GUO Fu-zhou, SONG Jian-tong, LIU Xiao, CHEN Zhi-hui, YANG Yi-biao, SUN Fei
2022, 15(1): 144-160. doi: 10.37188/CO.2021-0084
摘要:
The technology of enhancing fluorescence emission can increase the sensitivity of fluorescence detection and the brightness of Light Emitting Diodes (LEDs), and is of great significance in improving the performance of light-emitting devices. Since the metal structure has a good effect in enhancing the local field and fluorescence emission, and the flexible dielectric material has flexible bendability characteristics, on the basis of above, we propose a flexible structure composed of Metal-Dielectric-Metal (MDM) to enhance the fluorescence emission. The influence of the structure on the directional emission enhancement of quantum dots is systematically studied by using the finite difference time domain method. Theoretical calculations show that the local undulations and arcs of the flexible MDM structure can promote fluorescence enhancement and increase the quantum efficiency of the quantum dots located at the center of the structure by about 7 times. They can alao change the refractive index and thickness of the dielectric to achieve the tunability of the target wavelength. At the same time, the experimental results shows that the flexible MDM structure does have a positive effect on the fluorescence enhancement. This discovery is valuable for future display technologies and flexible light-emitting devices. It is of certain guiding significance for the development and application of high-efficiency flexible devices.