## 留言板

A high-sensitivity surface plasmon resonance (SPR) sensor comprising an eccentric core ten-fold photonic quasi-crystal fiber (PQF) with a D-shaped structure and coated with indium tin oxide (ITO) is designed and analyzed numerically. The eccentric core D-shaped structure makes analysis of liquids more convenient and also strengthens the coupling between the core mode and 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 measurement of liquid refractive indexes.

目的  由于X光安检图像存在背景复杂，重叠遮挡现象严重，危险品摆放方式、形状差异较大等问题，导致检测难度较高。  方法  针对上述问题，本文在YOLOv4的基础上，结合空洞卷积对其网络结构进行改进，加入空洞空间金字塔池化(atrous space pyramid pooling, ASPP)模型，以此增大感受野，聚合多尺度上下文信息。然后通过K-means聚类方法生成更适合X光安检危险品检测的初始候选框。其中，模型训练时采用余弦退火优化学习率，进一步加速模型收敛，提高模型检测精度。  结果  实验结果表明，本文提出的ASPP-YOLOv4检测算法在SIXRay数据集上的mAP达到85.23%。  结论  能有效减少X光安检图像中危险品的误检率，提高小目标危险品的检测能力。

目的  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。  方法  该光学系统采用二次成像结构型式以满足100%冷光阑效率，采用锗和硫化锌玻璃材料组合，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 μm~9.3 μm，视场角为1.37°×1.10°，F数为2。系统采用二次成像型式将系统出瞳后置于冷屏处，满足100%冷光阑效率，并引入高次非球面优化平衡系统像差。  结果  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，具有高的成像品质。  结论  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。

目的  紫外探测技术已广泛应用于人类的生产生活各领域，研究宽谱段紫外成像仪系统具有重要意义。  方法  通过推导色差理论公式，提出了单一材料校正宽谱段紫外成像仪光学系统色差的方案，结合高灵敏度大动态紫外成像探测器的性能指标，设计了仅一种透镜材料且所有透镜全部为球面的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对系统优化及像质评价。  结果  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。  结论  该系统不含非球面等光学元件，不仅加工装调易于实现，而且降低研制成本，将为宽谱段紫外成像光谱仪的设计奠定技术基础。

With the development of underwater optical communication, 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. The scintillation index of the vortex beam with topological charge m=2 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 meters, and the scintillation indices of both the vortex beam with m=2 and the Gaussian beam increase with the increase of the propagation distance.

Helmholtz-Kohlrausch effect (H-K effect) described the influence of color purity on the perceived brightness of a color object. Quantum dots (QD) based backlights can enhance the color quality of liquid crystal display (LCD) display with improved perceived brightness due to the well-known H-K effect. However, the H-K effect of QD embedded TV (also known as QLED TV) has not been fully demonstrated. In this paper, we investigated the H-K effect of QLED TV 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 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 color, 86% for pure green color, and 74-88% for bright colorful images. Moreover, QLED TV is much preferred than the YAG-LED TV even when both QLED TV and YAG-LED TV show the same perceived brightness. The results imply the bright future of QLED TV toward health display.

The single wedge compensation test method, as a testing method for large convex aspheric surface, 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 test process. To address this, a method is developed to calibrate the system error of single optical wedge test path using computer generation hologram (CGH). This study first analysed the source of the system error in the optical path of 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 is designed for optical wedge compensators with a diameter of 150 mm. Based on the analysis results, the calibration accuracy of the CGH is 1.98 nm RMS, and after calibration the test accuracy of single wedge compensation is 3.43 nmRMS, 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 test system errors of optical paths, address the problem of 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, are 0.023 and 0.011 λ RMS, respectively.

目的  为了对作物进行更灵敏、高效的生长监测，国内外相继设计了各类高光谱分辨率的光谱仪用来探测叶绿素荧光效率。本文对传统Offner光谱仪系统进行改进，得到了更高光谱分辨率的整体结构。  方法  选用了双反望远系统，光谱仪部分采用高刻线密度反射型凸面光栅，实现更高的光谱分辨率的光谱仪，在此基础上再添加放大透镜以满足长狭缝需求，同时得到了一种狭缝-像面在光栅同一侧的Offner结构。利用codev软件对望远系统和光谱仪部分的初始结构进行优化。  结果  结果表明，工作在670 nm~780 nm波段范围内时，光谱分辨率0.3 nm，在截止频率17 lp/mm下整体调制传递函数MTF>0.75，各视场条件下弥散斑均方根半径RMS<15 μm。  结论  可满足作物生长的叶绿素监测领域的高精度、实时性要求。

目的  在“太极计划”中，由卫星抖动引起的激光抖动噪声是影响激光干涉测量精度的主要噪声源之一，为保证测量精度，需抑制该噪声至10 nrad/√Hz@10 mHz。  方法  首先，采用由四象限光电探测器和相位计组成的角度敏感器进行角度信号测量，并利用马赫-曾德干涉仪结合比例-积分-微分控制技术，搭建了地基激光抖动噪声抑制系统。其次，分析了系统反馈控制能力以及系统对于抑制激光抖动噪声的有效性。  结果  实验结果表明：该系统可有效抑制激光抖动噪声，使得激光抖动噪声<4 nrad/√Hz@10 mHz。  结论  实验推进了“太极计划”对激光抖动噪声抑制水平的研究，为激光干涉测量奠定了物理实验基础。

2021, 14(5): 1039-1055.   doi: 10.37188/CO.2021-0003
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2021, 14(5): 1056-1068.   doi: 10.37188/CO.2021-0071
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2021, 14(5): 1069-1088.   doi: 10.37188/CO.2021-0044
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2021, 14(5): 1089-1103.   doi: 10.37188/CO.2021-0022
[摘要](128) [HTML全文](73) [PDF 7589KB](23)

2021, 14(5): 1104-1119.   doi: 10.37188/CO.2021-0033
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2021, 14(5): 1120-1132.   doi: 10.37188/CO.2021-0125
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2021, 14(5): 1133-1145.   doi: 10.37188/CO.2020-0216
[摘要](143) [HTML全文](59) [PDF 6559KB](22)

2021, 14(5): 1146-1161.   doi: 10.37188/CO.2021-0032
[摘要](374) [HTML全文](124) [PDF 5479KB](87)

2021, 14(5): 1162-1168.   doi: 10.37188/CO.2021-0001
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2021, 14(5): 1169-1176.   doi: 10.37188/CO.2021-0005
[摘要](125) [HTML全文](42) [PDF 5527KB](5)

2021, 14(5): 1177-1183.   doi: 10.37188/CO.2021-0020
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2021, 14(5): 1184-1193.   doi: 10.37188/CO.2020-0218
[摘要](210) [HTML全文](85) [PDF 5767KB](16)

2021, 14(5): 1194-1201.   doi: 10.37188/CO.2020-0220
[摘要](131) [HTML全文](42) [PDF 5647KB](22)

2021, 14(5): 1202-1211.   doi: 10.37188/CO.2020-0214
[摘要](168) [HTML全文](65) [PDF 5045KB](16)

2021, 14(5): 1212-1223.   doi: 10.37188/CO.2020-0219
[摘要](93) [HTML全文](32) [PDF 3914KB](8)

2021, 14(5): 1224-1230.   doi: 10.37188/CO.2021-0008
[摘要](127) [HTML全文](52) [PDF 3635KB](20)

2021, 14(5): 1231-1242.   doi: 10.37188/CO.2020-0129
[摘要](437) [HTML全文](130) [PDF 4279KB](24)

2021, 14(5): 1243-1250.   doi: 10.37188/CO.2021-0018
[摘要](136) [HTML全文](59) [PDF 4299KB](8)

2021, 14(5): 1251-1258.   doi: 10.37188/CO.2020-0068
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Optical properties of periodic double-well potential are one of the frontier research fields in laser physics and quantum optics. In this work, we have employed time-periodic double-well potential for the investigation of Fano-type resonant tunneling of photon-assisted Dirac electrons in a graphene system. Using a double quantum well structure, it is found that the resonant tunneling of electrons in a thin barrier between the two quantum wells splits the bound state energy levels, and the Fano-type resonance spectrum splits into two asymmetric resonance peaks. The shape of Fano peak is regulated by changing the phase, frequency, and amplitude, that can directly modulate the electronic transport properties of Dirac in graphene. Our numerical analysis shows that the relative phase of two oscillating fields can adjust the shape of the asymmetric Fano type resonance peak. When the relative phase increases from 0 to \begin{document}${\text{π}}$\end{document}, the resonance peak valley moves from one side of the peak to the other. In addition, the asymmetric resonance peak becomes symmetric at critical phase \begin{document}${{3{\text{π}} }/{11}}$\end{document}. Furthermore, the distribution of Fano peaks can be modulated by varying the frequency and amplitude of oscillating field and the structure of the static potential well. Finally, we suggest that these interesting physical properties can be used for the modulation of Dirac electron transport properties in graphene.
2021, 14(5): 1259-1272.   doi: 10.37188/CO.2020-0204
[摘要](49) [HTML全文](25) [PDF 4132KB](6)

In order to realize the demodulation of the cavity length of the fiber-optic FP sensor, a new optical wedge-type non-scanning correlation demodulation system is proposed, and the characteristics and structure of the devices used in the system are analyzed and studied. First, by simulating the light sources with different spectral distributions and the optical wedges with different surface reflectivities, the correlation interference signals are analyzed and the optimal structure parameters of the system components are given. Then by comparing the light intensity distribution characteristics of the Powell prism and cylindrical lens on the linear array CCD, more uniform spectral distribution is achieved. Finally, the specific implementation scheme and data processing method of the demodulation system are given. The experimental results show that when the light source spectrum has a Gaussian distribution and large spectral width and the reflectivity of the wedge surface is \begin{document}$R = 0.5$\end{document}, the characteristics of the correlation interference signal are obvious and convenient for demodulation. Finally, the demodulation system achieves the demodulation effect with an error of less than 0.025% within the cavity length range of 60 μm-100 μm. This optical wedge-type non-scanning correlation demodulation method can realize the sensing demodulation of the fiber-optic FP cavity and improve the power adaptability of different types of fiber-optic FP sensors.
2021, 14(5): 1273-1287.   doi: 10.37188/CO.2021-0015
[摘要](107) [HTML全文](43) [PDF 3895KB](4)

In order to realize the separation and release of nucleated red blood cells from peripheral blood and develop a safe and effective non-invasive technique to separate nucleated red blood cells for prenatal diagnosis of fetal diseases, an automatic cell smear preparation system based on hydrogel material was established, and a laser focusing and microscopic imaging system for recognizing and releasing nucleated red blood cells was constructed. Firstly, the mechanical structure of cell smear preparation machine was designed, the upper computer control software was designed based on single chip microcomputer, and a hydrogel membrane substrate smear was prepared by optimizing the slide-pushing angle and speed. MXene, a two-dimensional material, was introduced into temperature-sensitive hydrogel gelatin, and the near-infrared light response was realized on the surface of hydrogel membrane by using the near-infrared photothermal conversion characteristics of MXene. Then, the whole cell smear experiment was carried out on the surface of the hydrogel substrate membrane. A monolayer cell smear was prepared by optimizing the parameters of blood slide. Finally, the optical path of laser focusing and microscopic imaging was established. After the nucleated red blood cells were recognized and located, the light from an 808 nm laser source passed through a collimator lens and a convergent lens and was focused on the surface of the cell smear, which released cells under photothermal effect. A monolayer cell smear was processed and prepared, and then a photothermal effect was produced under the near-infrared light of 808 nm. After the control of the laser focusing system, a fixed cell-releasing area with a spot diameter of 300 μm was finally obtained. In this paper, the automatic slide-pushing technology was applied to the preparation of a monolayer cell smear based on hydrogel membrane, and the optical path of laser focusing and microscopic imaging was established. By using the near-infrared response and a thermal response of hydrogel membrane, the recognition and fixed-point release of nucleated red blood cells were realized, and the efficiency of separation and enrichment of nucleated red blood cells was improved. This technology has a broad application prospect in the field of prenatal screening and diagnosis.
2021, 14(5): 1288-1304.   doi: 10.37188/CO.2021-0004
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Compared with the commonly used simulation algorithms such as Finite Element Method (FEM) and Finite-Difference Time-Domain (FDTD) method, the Boundary Element Method (BEM) has the advantages of high accuracy, small memory consumption, and ability to deal with complex structures. In this paper, the basic principle of three-dimensional BEM is given, the corresponding program based on C++ language is written, and the Surface Plasmon Resonance (SPR) characteristics of a graphene nano-disk structure are studied. The Scattering Cross-Section (SCS) spectral lines of a graphene nano-disk under different chemical potentials, as well as the distributions of electromagnetic fields at the resonance wavelengths are calculated. The electromagnetic response of the graphene nano-disk in the infrared band is analyzed. In addition, considering the common corrugations of graphene materials caused by defects during processing, we study the influence of the geometric parameters of a convex structure in the center of the graphene nano-disk on the resonance intensity, wavelength and field distributions. A spring oscillator model of charge movement is used to explain the simulation results.
2021, 14(5): 1039-1055.   doi: 10.37188/CO.2021-0003

2021, 14(5): 1056-1068.   doi: 10.37188/CO.2021-0071

2021, 14(5): 1069-1088.   doi: 10.37188/CO.2021-0044

2021, 14(5): 1089-1103.   doi: 10.37188/CO.2021-0022

2021, 14(5): 1104-1119.   doi: 10.37188/CO.2021-0033

2021, 14(5): 1120-1132.   doi: 10.37188/CO.2021-0125

2021, 14(5): 1133-1145.   doi: 10.37188/CO.2020-0216

2021, 14(5): 1146-1161.   doi: 10.37188/CO.2021-0032

2021, 14(3): 447-457.   doi: 10.37188/CO.2020-0199

2021, 14(3): 458-469.   doi: 10.37188/CO.2020-0180

2021, 14(3): 470-486.   doi: 10.37188/CO.2020-0093

2021, 14(3): 487-502.   doi: 10.37188/CO.2020-0134

Acoustic-to-seismic coupling landmine detection technology based on the unique mechanical characteristics of landmines and the acoustic-to-seismic coupling principle has broad application prospects in safe and effective detection of landmines. However, a significant amount of work must be done to study the practical landmine detection system. Among them, the acoustic coupled surface vibration signals are very weak and complicated, which has always been a challenging problem to detect such signals accurately and quickly. In this paper, the non-contact laser measurement techniques of surface vibrations based on the principle of the acoustic-to-seismic coupling landmine detection technology were reviewed, including laser Doppler interferometry, electronic speckle pattern interferometry and laser self-mixing interferometry, etc., and the application feasibility of electronic speckle-shearing pattern interferometry in acoustic-to-seismic coupling landmine detection was analyzed.

2021, 14(3): 503-515.   doi: 10.37188/CO.2020-0039

2021, 14(3): 516-527.   doi: 10.37188/CO.2020-0051

2021, 14(2): 227-244.   doi: 10.37188/CO.2020-0126

2021, 14(2): 245-263.   doi: 10.37188/CO.2020-0121

Quasi-distributed fiber sensing systems play an important role in the fields of civil engineering, energy surveying, aerospace, national defense, chemicals, etc. Interrogation technology for quasi-distributed fiber sensing systems based on microwave photonics is widely used in high-speed and high-precision signal demodulation and sensor positioning in optical fiber multiplexing systems. Compared to conventional optical wavelength interrogation, this technology greatly improves system demodulation rate and compensates for the defects of traditional sensor positioning methods. This paper introduces the recent research progress of quasi-distributed fiber sensing interrogation technology based on microwave photonics; compares and analyzes the advantages and disadvantages of several existing microwave demodulation systems from the perspective of their fiber grating quasi-distributed sensing and fiber Fabry-Perot quasi-distributed sensing systems, respectively; and provides a summary of the prospective direction of future research in quasi-distributed fiber sensing interrogation technology based on microwave photonics.

2021, 14(2): 264-274.   doi: 10.37188/CO.2020-0193

2021, 14(2): 275-288.   doi: 10.37188/CO.2020-0098

2020, 13(6): 1171-1181.   doi: 10.37188/CO.2020-0033

2020, 13(6): 1182-1193.   doi: 10.37188/CO.2020-0049

ISSN 2095-1531

CN 22-1400/O4

CODEN ZGHUC8