美女caobi,亚洲婷婷六月

2022

Record 253 of

Title:Laser wireless power transfer and thermal regulation method driven by transient laser grating

Author(s):Yao, Dong(1,2); Gao, Bo(3); Qiang, Hongfu(1); Wang, Xueren(1); Wen, Keyao(2); Wang, Di(2)
Source: AIP Advances Volume: 12 Issue: 10 DOI: 10.1063/5.0106968 Published: October 1, 2022
Abstract:Wireless power transfer (WPT) technology uses non-conductive-wire methods to realize power transmission from the power-supply side to the load side, which is an advantageous energy supply method in long-distance, non-contact scenarios. Based on the photovoltaic (PV) effect, traditional laser WPT (LWPT) has the advantage of high transmission power. However, the cooling requirements of PV modules introduce additional structural composition and operating energy. In this paper, an LWPT (BeE-LWPT) technology based on the Seebeck effect is proposed, and a brand-new energy conversion mode is designed. Aiming at the limited hot area of the thermoelectric element periodically heated using the expanded beam laser, the improvement effect of the transient laser grating thermal regulation mechanism on BeE-LWPT is studied. Multiphysics simulations of the temperature response of the hot end of the copper plate modulated by the laser beam spot are carried out with commercial finite-element software. Compared with the traditional beam expansion method for temperature control, the proposed modulation method based on the transient laser grating has a more stable temperature response and a more uniform heating area, which means better thermal regulation effect. ? 2022 Author(s).
Accession Number: 20224212969991
Record 254 of

Title:Ultra-fast detail enhancement for a short-wave infrared image

Author(s):Chen, Yaohong(1); Zhang, Hui(1,2); Zhao, Zehao(1,2); Wang, Zhen(1); Wang, Hao(1); Kwan, Chiman(3)
Source: Applied Optics Volume: 61 Issue: 17 DOI: 10.1364/AO.455947 Published: June 10, 2022
Abstract:Image detail enhancement is critical to the performance of short-wave infrared (SWIR) imaging systems, especially to the long-range systems.However, the existing high-performance infrared (IR) image enhancement methods typically have difficulty in meeting the requirements of the imaging system with high resolution and high frame rate. In this paper,we propose an ultra-fast and simple SWIR image detail enhancement method based on the difference ofGaussian (DoG) filter and plateau equalization.Our method consists of efficient edge detail information extraction and histogram equalization. The experimental results demonstrated that the proposed method achieves outstanding enhancement performance with a frame rate around 50 fps for 1280×1024SWIRimages. ? 2022 Optica Publishing Group.
Accession Number: 20222512240988
Record 255 of

Title:Large Relative Aperture Optical System Design for All Day Star Sensor

Author(s):Zhang, Kaisheng(1,2); Su, Xiuqin(1); Ye, Zhilong(3)
Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 51 Issue: 11 DOI: 10.3788/gzxb20225111.1111003 Published: November 2022
Abstract:Star sensor is a high-precision space attitude measurement instrument with high precision， good autonomy and independent existence of other systems. It takes the starry sky as the working background and stars as the benchmark to obtain the attitude information of the spacecraft by detecting stars in different positions in space. Therefore， its accuracy is the key factor affecting the overall performance of the whole system. The all day star sensor is a star sensor that can still detect stars under the strong background in the daytime and has the anti-interference ability to the strong sky background. As the most important part of the optical system， its imaging quality is very important to improve the star detection ability of the star sensor. However， with the development of aerospace technology， space science has higher and higher requirements for the attitude accuracy of spacecraft. Therefore， in order to meet the needs of all-time high-precision detection， the lens of the star sensor optical system must adopt a large relative aperture to improve the star detection ability. In order to realize the all-time high-precision detection of class 3 stars by star sensor in J-band， this paper adopts the method of passive thermal difference design， carries out matching optimization according to the thermal difference performance difference between the optical system and structural materials， and then realizes lens thermal difference elimination. An all-time star sensor optical system with a large relative aperture is designed and completed. Firstly， the irradiance and signal-to-noise ratio of class 3 stars in the J-band are analyzed to determine the main parameters of the optical system， in which the focal length is 84 mm， the F number is 1.4， and the working spectrum range is 1.1 ~ 1.4 μm. The field angle is 8.4°. Secondly， considering that the optical system of the star sensor has the characteristics of a large relative aperture， long focal length and the influence of optical system distortion on the accuracy of star point extraction， the distortion free telephoto objective is selected as the initial structure of the optical system for optimization. In the process of optical system design， common optical materials and lens barrel materials are selected. By changing the shape and thickness of each lens， the focal power and air gap between each lens are reasonably matched， so as to realize the passive compensation non-heating design. After the optimized design， the dispersion spot size of the optical system is better than 30 when the defocus is 0.02 mm under the conditions of high and low temperature （-40 ℃~ +60 ℃） and vacuum μm. The color distortion is less than 0.018 mm， and the design results meet the design requirements. The inner surface of the star sensor is blackened， the light shield is designed with non-equidistant layout， and the surface is blackened with an SB-3A domestic extinction paint with high solar absorption， which can effectively reduce the weight under the condition of ensuring the effect. The inner baffle ring of the light shield adopts a 16 ° oblique angle， which can ensure good stray light suppression ability. The stray light of the optical mechanical system is simulated and analyzed by using TracePro software. The analysis results show that the stray light generated by the target in the field of view is 3×10-5 of the intensity of the target， the stray light intensity outside the field of view decreases rapidly from the order of 10-2， and the stray light intensity outside 18° is less than 10-4 of the strong light outside the field of view. Finally， the actual ground star observation test is carried out on the principle prototype. Through the star photos and three-dimensional energy diagram taken by the principle prototype， it can be seen intuitively that the signal intensity of the class 3 star target is much greater than the background intensity. After subsequent image processing， a clearer star observation effect can be obtained. Through theoretical analysis and design and practical observation experiments， it is verified that the optical system designed in this paper can meet the requirements of all-time high-precision detection of class 3 stars in J-band， which also shows the rationality of the design of the optical system. ? 2022 Chinese Optical Society. All rights reserved.
Accession Number: 20224513074627
Record 256 of

Title:Twisted Gaussian Schell-model breathers and solitons in strongly nonlocal nonlinear media

Author(s):Zhang, Shaohua(1); Zhou, Zhenglan(1); Zhou, Yuan(2,3); Xu, Huafeng(4); Yuan, Yangsheng(5); Han, Yashuai(1); Zhou, Zhengxian(1); Yao, Baoli(2); Qu, Jun(1)
Source: Optics Express Volume: 30 Issue: 18 DOI: 10.1364/OE.466117 Published: August 29, 2022
Abstract:Based on the Snyder-Mitchell linear model and the cross-spectral density (CSD) function, the analytical propagation formula of twisted Gaussian Schell-model (TGSM) beams in strongly nonlocal nonlinear medium (SNNM) is derived. Then the propagation characteristics of TGSM beam are studied. It is found that the soliton radius is jointly determined by the initial power, coherence length, and twist factor; the degree of spatial coherence is adjusted by changing the twist factor without affecting the soliton intensity. In the case of non-soliton properties, there is a threshold of coherence length which makes partially coherent beams have the same evolution law as completely coherent beams. Furthermore, increasing the twist factor, decreasing the coherence length and initial power can improve the beam quality of the beam propagating in SNNM. ? 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.
Accession Number: 20223412609216
Record 257 of

Title:Research on Coupling Efficiency Based on Fiber Optic Rotary Joints

Author(s):Song, Wei(1,2,3); Xie, Youjin(1,2); Li, Zhiguo(1,2); Hao, Wei(1,2); Yan, Peipei(1,2); Li, Xin(1,2); Sun, Chuandong(1)
Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 51 Issue: 11 DOI: 10.3788/gzxb20225111.1106005 Published: November 2022
Abstract:As an important part of modern communication system， satellite communication undertakes important tasks such as communication， earth observation， navigation and positioning in military and civil fields. The traditional spaceborne optoelectronic load realizes the data signal and power transmission between the relative rotating bodies through the slip rings. With the continuous development of optical fiber technology and related components， laser communication with optical fiber as the transmission medium has gradually replaced the traditional signal transmission with wires. The fiber optic rotary joints have the characteristics of a wide communication frequency band， strong anti-electromagnetic interference ability， strong confidentiality ability， fast transmission rate， low loss， etc. Its performance largely determines the service life of the satellite. Low loss and high reliability are important indicators of single-channel fiber optic rotary joints. This paper takes the single-channel fiber optic rotary joints as the research object. In order to achieve its low loss and high reliability goals， it is necessary to explore the factors affecting the insertion loss. The gap between the single-mode fiber and the gradient-index lens and the position error between the two gradient-index lens collimators are all important factors that affect the insertion loss of the fiber optic rotary connector. The Gaussian beam coupling has attracted the attention of universities and research institutions from all over the world. But the previous analysis ignored the influence of the position error between the fiber and the gradient-index lens on the coupling efficiency. There is no corresponding compensation method for the above-mentioned errors， which is crucial for improving performance parameters and reducing the difficulty of processing and assembly. This paper takes the single-channel fiber optic rotary joints as the research object. In order to achieve the goals of low loss and high reliability， it is necessary to explore the factors affecting the insertion loss. The fiber optic rotary connector studied in this paper uses two gradient-index lens collimators as the main optics. Theoretically， the propagation model of Gaussian beam in the construction of gradient-index lens is established， and the optical characterization parameters of the gradient-index lens are obtained by mathematical analysis method of light transmission matrix. In order to describe the propagation of the Gaussian beam in the gradient-index lens， the （x， y， z） and （x'， y'， z'） coordinate systems are established， and the electric field vector equations are established for the lenses at the receiving end and the transmitting end. Based on this equation， the influence of lateral offsets on the coupling efficiency of the system is discussed. Using the geometrical optics analysis method， the energy distribution equation under the separation misalignment is established， and the influence of the separation misalignment on the coupling efficiency of the system is analyzed. This paper design the single-channel fiber optic rotary joints with low loss as the key parameter by ZEMAX， and the optical model of the single-channel fiber optic rotary joints is established， and the optical parameters of the gradient-index lens are preliminarily determined. For the convenience of processing and assembly， the two gradient-index lenses are designed with the same parameters. First， without changing the working distance， set the distances to 0， 0.05 mm， 0.10 mm， 0.15 mm， 0.20 mm， and 0.25 mm between the optical fiber at the transmitting end and the gradient-index lens. In order to obtain the insertion loss at different positions， the value of the fiber at the receiving end and the gradient-index lens is changed. It can be seen from the analysis that the same insertion loss as the initial value can be obtained by adjusting the position of the optical fiber. This method can reduce the influence of the error between the optical fiber and the gradient-index lens. Secondly， by changing the lateral offsets and separation misalignment of the two gradient-index lenses， the effects of lateral offsets and separation misalignment on the insertion loss of the system are obtained. It should be noted that due to the particularity of the gradient-index lens， the lateral offsets cannot be so large that the Gaussian beam cannot be coupled into the fiber. The axial distance is controlled within 0~14 mm， and the radial distance is controlled within 0~0.25 mm. It can be seen from the simulation that the lateral offsets have a great influence on the insertion loss of the system， and it is necessary to strictly ensure the accuracy in processing and assembly. In view of the above errors， the insertion loss is reduced to 0.2 dB by the displacement method， which provides a reference for the optimal design of the single-channel fiber optic rotary joints. For the separation misalignment and lateral offsets between two gradient-index lenses， a beam steering technology based on wedge prism and flat glass is proposed. This method mainly uses two wedge prisms to achieve beam steering， the flat glass adjusts the transmission optical axis and the receiving optical axis to be on the same axis as possible. The insertion loss of systems can be reduced to 0.7 dB by beam steering technology， which greatly reduces the influence of errors. The difficulty of processing and assembly is reduced， and the reliability of the system can be improved. Finally， a test system for the insertion loss of a single-channel fiber optic rotary joints was built， and the position of the optical fiber and the gradient-index lens was adjusted with a high precision fiber alignment stage， and observed through a binocular microscope. By fitting the experimental data with the simulation data， the accuracy of the system design and simulation analysis is verified. ? 2022 Chinese Optical Society. All rights reserved.
Accession Number: 20224513074685
Record 258 of

Title:Design of high precision and compact focusing mechanism for aerial photoelectric remote sensor

Author(s):Zhang, Hongwei(1,2,3); Chen, Weining(3); Qu, Rui(3); Ding, Yalin(1); Wu, Li(4)
Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 51 Issue: 10 DOI: 10.3788/IRLA20211122 Published: October 2022
Abstract:Aiming at the defocusing problem of aerial photoelectric remote sensors in different working environments, a moving lens group is used to adjust the focus to ensure its imaging quality. The focusing mechanism adopts the anti-backlash screw nut pair as the transmission mechanism, adopts 6 precision bearings and elastic preload components as guide mechanism and adopts a pair of eddy current sensors and a diamond-shaped detected part as the displacement sensor to ensure the focusing accuracy to the greatest extent under the limited envelope size. The precision analysis of the focusing mechanism was carried out. And a test platform was built to carry out the transmission positioning accuracy experiment and the shaking accuracy experiment. The experimental results show that the transmission positioning accuracy of the focusing mechanism is within ±6 μm, and the shaking accuracy is within ±4″, which meets the design requirements of focusing accuracy proposed by the optical system. ? 2022 Chinese Society of Astronautics. All rights reserved.
Accession Number: 20224613118013
Record 259 of

Title:Analogous Optical Activity in Free Space Using a Single Pancharatnam–Berry Phase Element

Author(s):Liu, Sheng(1); Qi, Shuxia(1); Li, Peng(1); Wei, Bingyan(1); Chen, Peng(2); Hu, Wei(2); Zhang, Yi(1); Gan, Xuetao(1); Zhang, Peng(3); Lu, Yanqing(2); Chen, Zhigang(4,5); Zhao, Jianlin(1)
Source: Laser and Photonics Reviews Volume: 16 Issue: 1 DOI: 10.1002/lpor.202100291 Published: January 2022
Abstract:It is commonly believed that optical activity (OA) is manifested mainly in chiral media, but rare in non-chiral structures. Here, an analog of OA in free space is experimentally demonstrated by using a single liquid-crystal Pancharatnam–Berry phase element (PBPE), for which the mechanism is highly consistent with that of the traditional OA. The specifically designed PBPE supports the direction-dependent polarization rotation of a Bessel beam with controllable "rotatory power." Such a polarization rotation can be revoked by another PBPE with the same structure. Unlike in a chiral medium, this scheme shows simultaneous realization of equivalent leverotation and dextorotation merely by switching the optical element orientation, promising for applications non-magnetic optical devices such as optical isolators. ? 2021 Wiley-VCH GmbH
Accession Number: 20214611158180
Record 260 of

Title:Study on Multispectral Polarization Characteristics of Biological Tissues

Author(s):Qiao, Wen-Long(1,2); Zhou, Liang(1); Liu, Zhao-Hui(1); Gong, Yong-Hui(3); Jiang, Le(1); Lü, Yuan-Yuan(1,2); Zhao, He-Tong(1,2)
Source: Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis Volume: 42 Issue: 4 DOI: 10.3964/j.issn.1000-0593(2022)04-1070-06 Published: April 2022
Abstract:Biological tissues are very complicated with strong scattering characteristics. The light-source of detecting physiological parameters of tissues is critical. Combined with the advantages of polarization imaging, this paper studies the multispectral polarization characteristics of biological tissues. We established uniform monolayer biological tissue samples based on the distribution of different particle sizes and simulated the scattering model with single-particle by combining Rayleigh and Mie scattering theory. Rayleigh theory has good forward and backward scattering symmetry; Mie theory has strong forward scattering characteristics. The two scattering models are closely related to the size parameter, a dimensionless quantity, depending on the incident wavelength and the size of scattered particles. Mie theory is generally used as the research model in biological tissues. We used a Monte Carlo method to simulate the transmission characteristics of polarized light in the tissue model. The wavelength range is 400~1 000 nm. In this paper, we have simulated four typical polarization states, (horizontally polarized light, vertically polarized light, 450 linearly polarized light and right-rotated circularly polarized light). The experiment system used a white LED lamp as a light source. It used filters to obtain different wavelength beams, a color camera was used to record the image of the target, two groups of linear polarizers and right-rotated circular polarizers were used as polarizers and analyzers to test horizontally polarized light, and right-rotated circular polarized light with wavelengths of 450, 525, 550, 590, 610, 650 and 690 nm, respectively, and the target is our palm. Both simulation and experimental results show that with the increase of wavelength, the degree of polarization (DOP) of linearly polarized light after backscattering from skin tissue shows an overall upward trend, while that of circularly polarized light is on the decline. However, the overall DOP of circularly polarized light is higher than that of linearly polarized light, which indicates that circularly polarized light has better polarization retention than linearly polarized light in biological tissues and is more suitable for detecting physiological information. Our study has confirmed the multispectral characteristics of circularly polarized light and linearly polarized light transmitted in tissues, which provided theoretical support for obtaining multispectral polarization physiological parameters. ? 2022, Peking University Press. All right reserved.
Accession Number: 20221511947488
Record 261 of

Title:Visible-Infrared Person Re-Identification via Partially Interactive Collaboration

Author(s):Zheng, Xiangtao(1); Chen, Xiumei(2,3); Lu, Xiaoqiang(4)
Source: IEEE Transactions on Image Processing Volume: 31 Issue: DOI: 10.1109/TIP.2022.3217697 Published: 2022
Abstract:Visible-infrared person re-identification (VI-ReID) task aims to retrieve the same person between visible and infrared images. VI-ReID is challenging as the images captured by different spectra present large cross-modality discrepancy. Many methods adopt a two-stream network and design additional constraint conditions to extract shared features for different modalities. However, the interaction between the feature extraction processes of different modalities is rarely considered. In this paper, a partially interactive collaboration method is proposed to exploit the complementary information of different modalities to reduce the modality gap for VI-ReID. Specifically, the proposed method is achieved in a partially interactive-shared architecture: collaborative shallow layers and shared deep layers. The collaborative shallow layers consider the interaction between modality-specific features of different modalities, encouraging the feature extraction processes of different modalities constrain each other to enhance feature representations. The shared deep layers further embed the modality-specific features to a common space to endow them the same identity discriminability. To ensure the interactive collaborative learning implement effectively, the conventional loss and collaborative loss are utilized jointly to train the whole network. Extensive experiments on two publicly available VI-ReID datasets verify the superiority of the proposed PIC method. Specifically, the proposed method achieves a rank-1 accuracy of 83.6% and 57.5% on RegDB and SYSU-MM01 datasets, respectively. ? 1992-2012 IEEE.
Accession Number: 20224613110632
Record 262 of

Title:Design and Preparation of Large Aperture High Reflective Films Composed Entirely of Dielectric Materials for Multi-band Application

Author(s):Shi, Yun-Yun(1); Xu, Jun-Qi(1); Liu, Zheng(2); Zhang, Kai-Feng(3); Su, Jun-Hong(1); Yuan, Song-Song(1); Liu, Qi(1)
Source: Surface Technology Volume: 51 Issue: 4 DOI: 10.16490/j.cnki.issn.1001-3660.2022.04.035 Published: 2022
Abstract:This paper aims to select TiO2 and SiO2 high and low refractive index materials, design and prepare 500~650 nm, 780~830 nm, 1 050~1 080 nm three-band compatible dielectric high reflective films. The spectral properties, stress characteristics and laser damage resistance of high reflective films composed entirely of dielectric materials for multi-band application are studied, and the large aperture film samples with good stress state are obtained. The process parameters of monolayer films were studied, with the monitoring wavelength 560 nm, based on the electric field intensity distribution, and film structure was optimized to be G/(HL)8H(2L)4 (1.4H1.4L)8H2L(1.9H1.9L)81.9 H/A. Low refractive index layers were added between different film stacks to suppress the nominal problem, and the reflectance spectral was smoothed, wide-band large-size multilayer high reflective film with good performance was successfully prepared on a large aperture substrate of ф220 mm by ion beam assisted electron beam evaporation technology. Its reflectance spectral was in the visible light range of 500~650 nm, with the average reflectivity of 99.5%, the peak reflectivity of 99.9%, the minimum reflectivity was 95.1%; within the scope of 780~830 nm, the peak reflectivity was 99.9%, and the average reflectivity was 99.8%, and the minimum reflectivity was 99.6%; in the 1 050~1 080 nm band, its average reflectivity could reach 99.8%, and the peak reflectivity reached 99.9%, and the minimum reflectivity reached 99.7%; reflectance spectral of large aperture film sample at different positions were high consistent. The laser-induced damage threshold of film was 7.1 J/cm2, and the residual stress was –293.59 MPa. The film thickness uniformity of large aperture film sample is good, and the film is compact without wrinkle, crack and falling off phenomena, with higher fastness and excellent laser protection performance. ? 2022, Chongqing Wujiu Periodicals Press. All rights reserved.
Accession Number: 20223112528981
Record 263 of

Title:Design of the scintillator imaging lens for the neutron imaging system at the 100 kJ-level laser facility

Author(s):Li, Qiukai(1,2,3); Chen, Zhongjing(3); Xu, Tao(3); Yan, Yadong(1); Wang, Feng(3); He, Junhua(1)
Source: Review of Scientific Instruments Volume: 93 Issue: 4 DOI: 10.1063/5.0086782 Published: April 1, 2022
Abstract:Deuterium-tritium neutron yield has reached up to about 1013 at the 100 kJ-level laser facility, which makes measurement of neutron emission images possible with the neutron imaging system. There are two methods to collect neutron images from the scintillator array, optical fiber taper and the lens system. Here, we report a design of the lens system for the neutron imaging system at the 100 kJ-level laser facility. The lens system, which consists of a nine-element collecting lens, with a spatial resolution of 20 μm and a light-collection efficiency of 5.9% has been designed. ? 2022 Author(s).
Accession Number: 20221712030731
Record 264 of

Title:Design and analysis of radial supports for a large aperture prism

Author(s):Wen, Wansha(1,2,3); Ruan, Ping(1,3); Lv, Tao(1,2,3)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12166 Issue: DOI: 10.1117/12.2616346 Published: 2022
Abstract:WFOS (Wide-field Optical Spectrograph) will be seriously affected by atmospheric dispersion on imaging quality in its operating wavelength range1 (0.31-1.0 micron). ADC (Atmospheric Dispersion Corrector)2 can compensate atmospheric dispersion for light deflection of different wavelengths. The main optical elements of a LADC3 (Linear Atmospheric Dispersion Corrector) are two large aperture transmission prisms whose optical axes are placed horizontally. The prisms are placed opposite to 180° and separated by a certain distance in the direction of the optical axis to generate the amount of dispersion compensation. the large-diameter wedge prisms not only make a linear motion in the optical axis direction but also operate rotary motion separately. Because of the non-rotational symmetry and large mass of the wedge prism, gravity has a serious effect on the surface deformation of the prism. In addition, the prisms have to withstand ±20°C temperature change when they work. a support system is proposed and a comparative analysis is operated to estimate performance of support forms with different number of supports. Different circumferential support positions three, four, six, and eight schemes are analyzed and compared. in addition, the influence of different supports layouts based on the six supports scheme are analyzed. The 3D models are established and finite element analyses are conducted to evaluate the support performance via the surface RMS values which show that the design can meet the current design requirements for the support scheme. ? COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.
Accession Number: 20220911734760

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