1 长春理工大学光电工程学院,吉林 长春 130022
2 长春理工大学电子信息工程学院,吉林 长春 130022
火炮整体性能评价体系中,身管缠角是至关重要的指标之一,现有缠角测量方法存在系统复杂、测量精度不高的问题,本文提出一种基于全景成像的膛线自动跟踪身管缠角测量方法。利用全景成像技术获取身管内膛全景图像,在极坐标系下推导内膛全景环形图像增强映射函数;通过建立环形模板匹配模型跟踪沿身管方向预设的阴阳膛线的边缘,完成膛线旋转角的粗定位;根据周期阴阳膛线图像对比度设计目标函数,优化目标函数完成膛线旋转角的精定位,结合身管轴向距离解算身管缠角。真实身管缠角测量实验结果表明,所提方法测量精度优于1′,能够满足实际缠角测量中的应用需求。
缠角测量 全景成像 火炮身管 膛线跟踪 光学学报
2023, 43(22): 2212002
Author Affiliations
Abstract
1 Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
2 Department of Physics and Engineering Physics, Tulane University, New Orleans, USA
Two-dimensional (2D) semiconductors have captured broad interest as light emitters, due to their unique excitonic effects. These layer-blocks can be integrated through van der Waals assembly,i.e., fabricating homo- or heterojunctions, which show novel emission properties caused by interface engineering. In this review, we will first give an overview of the basic strategies that have been employed in interface engineering, including changing components, adjusting interlayer gap, and tuning twist angle. By modifying the interfacial factors, novel emission properties of emerging excitons are unveiled and discussed. Generally, well-tailored interfacial energy transfer and charge transfer within a 2D heterostructure cause static modulation of the brightness of intralayer excitons. As a special case, dynamically correlated dual-color emission in weakly-coupled bilayers will be introduced, which originates from intermittent interlayer charge transfer. For homobilayers and type Ⅱ heterobilayers, interlayer excitons with electrons and holes residing in neighboring layers are another important topic in this review. Moreover, the overlap of two crystal lattices forms moiré patterns with a relatively large period, taking effect on intralayer and interlayer excitons. Particularly, theoretical and experimental progresses on spatially modulated moiré excitons with ultra-sharp linewidth and quantum emission properties will be highlighted. Moiré quantum emitter provides uniform and integratable arrays of single photon emitters that are previously inaccessible, which is essential in quantum many-body simulation and quantum information processing. Benefiting from the optically addressable spin and valley indices, 2D heterostructures have become an indispensable platform for investigating exciton physics, designing and integrating novel concept emitters.Two-dimensional (2D) semiconductors have captured broad interest as light emitters, due to their unique excitonic effects. These layer-blocks can be integrated through van der Waals assembly,i.e., fabricating homo- or heterojunctions, which show novel emission properties caused by interface engineering. In this review, we will first give an overview of the basic strategies that have been employed in interface engineering, including changing components, adjusting interlayer gap, and tuning twist angle. By modifying the interfacial factors, novel emission properties of emerging excitons are unveiled and discussed. Generally, well-tailored interfacial energy transfer and charge transfer within a 2D heterostructure cause static modulation of the brightness of intralayer excitons. As a special case, dynamically correlated dual-color emission in weakly-coupled bilayers will be introduced, which originates from intermittent interlayer charge transfer. For homobilayers and type Ⅱ heterobilayers, interlayer excitons with electrons and holes residing in neighboring layers are another important topic in this review. Moreover, the overlap of two crystal lattices forms moiré patterns with a relatively large period, taking effect on intralayer and interlayer excitons. Particularly, theoretical and experimental progresses on spatially modulated moiré excitons with ultra-sharp linewidth and quantum emission properties will be highlighted. Moiré quantum emitter provides uniform and integratable arrays of single photon emitters that are previously inaccessible, which is essential in quantum many-body simulation and quantum information processing. Benefiting from the optically addressable spin and valley indices, 2D heterostructures have become an indispensable platform for investigating exciton physics, designing and integrating novel concept emitters.
van der Waals assembly interface interaction interlayer gap twist angle intralayer and interlayer excitons moiré excitons Journal of Semiconductors
2023, 44(1): 011001
1 汕头大学理学院, 广东 汕头515063
2 东莞理工学院电子工程与智能化学院, 广东 东莞523808
全光纤干涉仪具有结构简单、制作方便且灵敏度高的特点, 近年来已广泛应用于各种传感领域。提出了一种基于多模光纤错位熔接于两单模光纤之间的全光纤干涉仪, 并将其应用于矢量扭转测量。实验证明, 若以强度解调, 传感器在顺时针及逆时针扭转时的灵敏度分别为 -0.225 dB/(°·m)和0.148 dB/(°·m); 若以波长解调, 传感器在顺时针及逆时针扭转时的灵敏度则为-0.259 nm/(°·m)和0.222 nm/(°·m)。不管采用哪种解调方法, 传感器在0~180o 范围内的线性拟合度都大于97%。提出的全光纤扭转传感器结构简单且性能良好, 可以用于建筑形貌及结构健康监控等工程应用。提出的全光纤干涉仪在未来还可用于其他领域的传感测量, 如温度、曲率等。
全光纤干涉仪 光纤传感器 单模-多模-单模光纤结构 扭转传感器 灵敏度 all-fiber interferometer fiber-optic sensor single-multi-single mode fiber structure twist sensor sensitivity
1 太原科技大学 应用科学学院, 太原 030024
2 中国科学院 合肥物质科学研究院 安徽光学精密机械研究所 大气光学重点实验室, 合肥 230031
为了得到一种新型椭圆扭曲多高斯-谢尔模(TMGSM)光束, 采用Mercer模式展开的方法进行了理论分析和验证, 证明了多高斯-谢尔模关联结构可携带扭曲相位, 详细研究了其在梯度折射率光纤中传输时的光强和相干度演化。结果表明, 椭圆TMGSM光束在梯度折射率光纤中传输时, 光强和相干度分布随着传输距离的增加发生周期性旋转, 并在0.5L(L为周期)的整数倍处偏转π/2, 其旋转角速度呈非线性变化且与扭曲因子的大小有关; 增大多高斯模数, 焦平面处光强分布的平顶区域增大, 相干度分布轮廓变小。此研究结果在光纤通信、聚焦成像、光学捕获等方面具有潜在的应用前景。
激光光学 扭曲相位 Mercer模式展开理论 多高斯关联 梯度折射率光纤 laser optics twist phase Mercer model expansion theory multi-Gaussian correlation gradient index fibers
强激光与粒子束
2021, 33(11): 111010
本文推导径向偏振部分相干扭曲光束(RPPCTB)在各向异性大气湍流中传输因子和空间扩展的解析表达式,主要分析扭曲因子等光束参数及各向异性因子等大气湍流参数对光束传输特性的影响,通过相应的数值模拟计算分析初始相干长度、束腰宽度、波长、扭曲因子、各向异性因子、湍流内尺度、湍流外尺度和广义指数参数对光束传输质量的影响。仿真结果表明,通过减小光束的初始相干长度,增加束腰宽度和波长,可以提高光束的传输质量,而增大光束的扭曲因子,光束有更小的传输因子,这表明通过合理地调控光束的扭曲相位,可以有效提高光束的抗湍流能力。
相干光学 径向偏振部分相干扭曲光束 扭曲因子 传输因子 各向异性大气湍流 激光与光电子学进展
2021, 58(21): 2103001
广西师范大学物理科学与技术学院,广西 桂林 541004
提出了一种基于预扭制保偏光纤(PMF)Sagnac环形镜结构的光纤扭转传感器,该传感器可以同时实现扭转方向的判别和扭转角度的测量。此结构的传感部分由熔接在两段2 mm长的多模光纤(MMF)中间2 cm长预扭制的熊猫型PMF构成,通过透射光谱中谐振波谷波长或功率变化的测量,实现扭转方向判别和扭转角度的测量。实验结果表明,该传感器具有较高的灵敏度。逆时针扭转时,谐振波谷波长随着扭转角度的增大发生蓝移,波长灵敏度最大为-455 pm·rad-1·m,功率灵敏度为-1.35 dB·rad-1·m;顺时针扭转时,谐振波谷波长随着扭转角度的增大发生红移,波长灵敏度最大为182 pm·rad-1·m,功率灵敏度为2.20 dB·rad-1·m。该传感器具有结构和制作简单、成本低廉等优点,在扭转或者旋转测量领域具有潜在的应用前景。
光纤光学 光纤传感器 保偏光纤 Sagnac环 扭转测量 激光与光电子学进展
2021, 58(17): 1706007
1 中国科学院 长春光学精密机械与物理研究所,吉林 长春 130033
2 中国科学院大学,北京 100049
液晶偏振光栅是一种基于几何相位原理的新型光栅器件,可以通过调控液晶光轴的空间分布来实现对入射光相位、偏振态等的调制。传统的液晶偏振光栅在正入射及波段范围较小时可以达到很高的衍射效率,但其在宽波段范围内难以保持很高的衍射效率,大角度入射时衍射效率下降明显。多层扭曲结构的提出使这些问题可以得到解决,但引入了新的问题,如何精准控制扭曲角及厚度的大小。基于此问题,本文提出了一种新型的基于琼斯矩阵的液晶偏振光栅的扭曲角及厚度的测量方法,使用差值拟合的方法消除了由于整个波段折射率变化引起的误差,可以准确得到液晶片的扭曲角和厚度。分析了扭曲液晶片和扭曲液晶偏振光栅的异同,基于扭曲液晶片的测量结果可以得到相同条件下制备的液晶偏振光栅的扭曲角及厚度。实验结果表明:对厚度的测量误差小于2%,对扭曲角的测量误差小于±0.5°。该方法能够快速和方便地实现对扭曲角及厚度的精准测量,有很高的测量准确性及稳定性,并分析了手性剂的浓度和扭曲角之间的关系,对扭曲液晶偏振光栅的制备方法提供了理论依据。
液晶 偏振光栅 扭曲角 厚度 琼斯矩阵 liquid crystals polarization grating twist angle thickness Jones matrix
1 南京航空航天大学 自动化学院,江苏 南京 211106
2 北京航天时代光电科技有限公司,北京 100091
光纤环在磁场中产生磁致非互异性误差,成为制约高精度干涉型光纤陀螺(以下简称高精度光纤陀螺)应用的主要因素之一,而误差与磁场强度、光纤扭转率有关。由于光纤扭转导致的光纤环磁场灵敏度达到10 (°)·h−1·Gs−1以上,即使采用坡莫合金对磁场屏蔽,屏蔽效能仅能达到30 dB左右,难以满足高精度光纤陀螺的应用需求。文中通过等效电路模型和有限元仿真分析了屏蔽材料连接缝隙对屏蔽效能的影响,通过公式计算了扭转率对磁场灵敏度的影响。根据分析,提出了将屏蔽材料由螺钉连接改为激光焊接并对光纤进行退扭的改进方法。通过光纤退扭,光纤环磁场灵敏度降低了89.3%;通过对连接缝隙激光焊接,屏蔽效能由 31 dB 提高到 64 dB以上,磁场灵敏度由 0.026 5 (°)·h−1·Gs−1 降低到了 0.000 4 (°)·h−1·Gs−1以下,且变温环境下陀螺零偏稳定性提高了7.5%以上。改进措施能够提高光纤环在磁场和温度环境下的精度,满足高精度光纤陀螺性能要求。
高精度光纤陀螺 磁场 连接缝隙 激光焊接 退扭 high-precision IFOG magnetic field connection gap laser welding de-twist 红外与激光工程
2021, 50(4): 20200239