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2020

Record 265 of

Title:Photonic RF and Microwave Integrator Based on a Transversal Filter with Soliton Crystal Microcombs

Author(s):Xu, Xingyuan(1); Tan, Mengxi(2); Wu, Jiayang(2); Boes, Andreas(3); Corcoran, Bill(4); Nguyen, Thach G.(3); Chu, Sai T.(5); Little, Brent E.(6); Morandotti, Roberto(7,8); Mitchell, Arnan(3); Moss, David J.(2)
Source: IEEE Transactions on Circuits and Systems II: Express Briefs Volume: 67 Issue: 12 DOI: 10.1109/TCSII.2020.2995682 Published: December 2020
Abstract:We demonstrate a photonic RF integrator based on an integrated soliton crystal micro-comb source. By multicasting and progressively delaying the input RF signal using a transversal structure, the input RF signal is integrated discretely. Up to 81 wavelengths are provided by the microcomb source, which enable a large time-bandwidth product of 81. Our approach also features a high degree of reconfigurability. By simply adjusting the value of dispersion (i.e., the length of dispersive fibre), the integration time window and resolution can be reconfigured to accommodate a diverse range of applications. We employed 13 km of standard single-mode fibre to achieve a large integration time window of 6.8 ns, a time resolution as fast as 84 ps, with a broad bandwidth of 11.9 GHz. In addition, we perform signal integration of a diverse range of input RF signals including Gaussian pulses with varying time widths, dual pulses with varying time intervals and a square waveform. The experimental results show good agreement with theory. These results verify our microcomb-based integrator as a competitive approach for RF signal integration with high performance and potentially lower cost and footprint. ? 2004-2012 IEEE.
Accession Number: 20205009605821
Record 266 of

Title:Design of ultra-compact optical detection system with large field of view

Author(s):Ma, Zi-Xuan(1,2); Li, Xu-Yang(1,2); Ren, Zhi-Guang(1,3); Chu, Nan-Qing(1,2)
Source: Guangxue Jingmi Gongcheng/Optics and Precision Engineering Volume: 28 Issue: 12 DOI: 10.37188/OPE.20202812.2581 Published: December 2020
Abstract:To achieve the accurate detection of 14th-magnitude targets, a large-field-of-view optical detection system was designed. First, according to the selected CCD231-84 E2V photodetector, the initial parameters, such as system entrance pupil and focal length, were calculated. Then, based on the selected parameters, the initial structure was selected, and the form of the Maxutov telescope was selected and improved. Then, the detection performance of the design results was analyzed. Finally, a tolerance analysis and optimization of the designed system were conducted so that it could meet the needs of processing and assembly. The design and analysis results indicate that the optical detection system adopts a spherical catadioptric mirror surface, the total length of the system is 350 mm, the full field of view for a 30 μm surrounding energy distribution is >86%, and the maximum distortion is ? 2020, Science Press. All right reserved.
Accession Number: 20210409825895
Record 267 of

Title:Freeform-Surface-Based Optical Detection System with Large Relative Aperture and Large Field of View

Author(s):Ma, Zixuan(1,2); Li, Xuyang(1,2); Ren, Zhiguang(1,3); Chu, Nanqing(1,2)
Source: Guangxue Xuebao/Acta Optica Sinica Volume: 40 Issue: 17 DOI: 10.3788/AOS202040.1722002 Published: September 10, 2020
Abstract:In order to realize the requirements of the sensitivity, detection timeliness, aperture and total length of an optical detection system in the space debris detection scenario, we design a space optical detection system with a large relative aperture and large field of view. Moreover, based on the detector index and target characteristics, we determine the design parameters and realize the detection of 12.5 magnitude stars. The system uses an asymmetrical double Gaussian lens group optical structure and has the working band of 450-850 nm, field of view of 20°, F number of 1.05, and entrance pupil diameter of 150 mm. We design the front surface of a lens in the system based on an XY polynomial freeform surface. The design and analysis results show that the diffuse spot of the system is within the 2×2 detection pixels, the surrounding full field-of-view energy ratio within the 2×2 detection pixels is larger than 86%, and the maximum distortion is less than 1.4%. The optical detection system possesses a compact structure, a reasonable aperture, good detection effect, high detection sensitivity, and strong timeliness. The performance of the adopted materials meets the conditions of space use and matches up with the optical processing capability. The designed detection system can be used for the accurate detection of space debris. ? 2020, Chinese Lasers Press. All right reserved.
Accession Number: 20204709510957
Record 268 of

Title:Transparent and hydrophobic hexylene-bridged polymethylsiloxane/sio2 composite coating with tunable refractive index and its application for broadband antireflection

Author(s):Zhang, Ce(1); Xu, Yao(2)
Source: Thin Solid Films Volume: 701 Issue: DOI: 10.1016/j.tsf.2020.137944 Published: 1 May 2020
Abstract:Regulating refractive index over a wide range plays a key role in the design and fabrication of broadband antireflective coating in many optical energy-related fields. In this paper, hydrophobic refractive-tunable coating was fabricated from an effective solution mixing method starting from a synthesis solution of silica (SiO2) nanoparticles which was developed for dispersing nanoparticles into dense hexylene-bridged polymethylsiloxane polymer. In the mixing process, the microstructure and chemical structure of hexylene-bridged polymethylsiloxane/SiO2 were analyzed by fourier transform-infrared spectrometer and transmission electron microscope. Specially, the relationship between the microstructure and optical properties was also well investigated. Silica nanoparticles were dispersed homogeneously in polymer matrix modulating the refractive index of composite coating ranging from 1.16 to 1.47. When the composite coating with refractive index of 1.36 was used as the bottom layer and hexamethyldisilazane modified SiO2 coating with refractive index of 1.16 was used as the top layer. Thus-obtained double-layer broadband antireflective coating was fabricated with excellent broadband antireflective performance. In addition, the double-layer broadband silica antireflective coating showed good environmental stability. This work provides an alternative way to prepare a broadband antireflective coating for some applications in energy harvesting and optical devices. ? 2020 Elsevier B.V.
Accession Number: 20201308337246
Record 269 of

Title:Development of the Control System of High Speed Synchronous Rotating Mirror for Space Laser Ranging

Author(s):Haitao, Wang(1,4); Yu, Cao(1,2,3,4,5); Xiong, Gao(1,4); Xin, Zhang(1,4); Junfeng, Han(1,3,4); Meilin, Xie(1,4); Peng, Liu(1,3,4); Feng, Jing(1,3,4)
Source: 2020 IEEE 3rd International Conference on Electronics Technology, ICET 2020 Volume: Issue: DOI: 10.1109/ICET49382.2020.9119699 Published: May 2020
Abstract:With the development of space technology and aerospace industry, space distance measurement has become an important research content in space field. The traditional radar ranging is easily interfered by space high-energy particles and electromagnetic waves in space, and the measurement accuracy is low, which cannot meet the requirements of high-precision measurement. The air in the space is thin and the temperature changes violently, so it is impossible to carry out acoustic ranging with super measurement accuracy. Laser ranging technology is an automatic non-contact measurement method, which is not sensitive to electromagnetic interference, has strong anti-interference ability and high measurement accuracy. Compared with the general optical ranging technology, it has the advantages of convenient operation, simple system and allday working. Compared with radar ranging, laser ranging has strong anti-interference ability and high precision. In this paper, a high-speed synchronous rotating mirror system is developed to meet the requirements of the splitting of the transmitting and receiving optical paths in laser ranging. It is installed in the optical path of the large-scale laser ranging system, driving the mirror body to rotate stably and at high speed, realizing the splitting of the optical path and generating the pulse signal synchronous with the mirror body position to send to the laser, which is used for the timing of launching the synchronous laser machine. Finally, through the experimental test, when the speed reaches 3000 rpm, the peak speed error is less than 1rmpPP, the mirror shake amount is 15.56 , and the equipment vibration is 8.9 μ m, which meets the needs of the scheme[10]. ? 2020 IEEE.
Accession Number: 20202808913733
Record 270 of

Title:Research on measurement optical axis eccentricity and fitting method of aspheric mirror

Author(s):Fu, Xi Hong(1); Li, Shuo(1); Xue, Li(1); Kang, Shi-Fa(1); Zheng, Xiang-Ke(1); Ma, Na-Na(1); Dang, Qian(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11439 Issue: DOI: 10.1117/12.2550273 Published: 2020
Abstract:A method to measurement of optical axis eccentricity and fitting about the aspheric mirror with the high-precision three-coordinate measuring machine(CMM) is presented. By establishing 2d/3d measurement coordinate system, The axis of fitting of the cylinder is selected according to the machining and assembly reference of aspheric mirror, Generating a number of concentric circles automatic measurement strategies, And make the points on each equal circumference, The probe head of the CMM is sampled on the surface of the measured aspheric mirror according to the measured strategy path to obtain the point coordinates of the distance of the reference axis, the measured surface is fitted to obtain the eccentricity of the aspheric mirror optical axis. Hyperboloid concave mirror to make use of the proposed method in the practical testing, the results show the actual processing of eccentricity is 0.0190mm, the standard deviation of 3.6×10-4mm, to meet the requirements of the design of eccentricity is less than or equal to 0.02mm.And testing the high precision centering lathe cutting machine frame fixed axis aspheric reflector components, the data indicators meet the requirements of assembly process. The accuracy of this method is high, and the traditional measuring method is easy to be affected by the precision of the tooling and easy to scratch the mirror. With large work surface, large caliber, back light weight loss (special-shaped structure) of aspheric mirrors optical axis eccentricity detection, not only suitable for different aperture aspheric mirrors the processing quality of qualified determination, but also in the machining, high precision of aspheric mirrors system with adjustable guiding role and effectively promote R-C spherical reflector optical system assembly accuracy and efficiency. ? COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.
Accession Number: 20201508381379
Record 271 of

Title:Research on technology of measuring and correcting the optical axis deviation of high-order aspheric lens

Author(s):Xihong, Fu(1); Shifa, Kang(1); Yu, Lei(1); Hua, Li(1); Peng, Wang(1); Nana, Ma(1); Qian, Dang(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11568 Issue: DOI: 10.1117/12.2574922 Published: 2020
Abstract:On the basis of optical theory, the mathematical model of axisymmetric high-order aspherical curve and the curve characteristic parameters related to the locus of aspherical surface are summarized. The non-contact precise measurement and correction of the central deviation of axisymmetric high-order aspherical lens based on autocollimated centering principle and spectral confocal displacement sensing technology are introduced. The methods of measuring the center deviation of aspheric lens with concave and convex surfaces are given.The aspheric measuring device of Trioptics double optical path center deviation measuring instrument is used to measure the axisymmetric high-order aspheric lens,Through several measurements and modifications, the final results meet the requirements of the whole optical system for the optical axis deviation of the axisymmetric high-order aspheric lens.The technology of measuring and correcting the center deviation of high-order aspheric lens with axial symmetry introduced in the paper has high non-contact measuring accuracy, which can guide the adjustment amount and position direction of the coincidence of the axis of symmetry and the axis of mechanical rotation of aspheric lens. It can be widely used in the process of on-line processing, testing and systematic adjustment of aspheric lens and aspheric mirror with different apertures.While ensuring the accuracy of aspheric surface, it can improve the quality of finish grinding process, save a lot of time for polishing process, and play a guiding role in its processing and manufacturing process and high-precision system installation, so as to greatly improve the processing efficiency of axisymmetric high-order aspheric surface and the final optical system installation and adjustment accuracy. ? 2020 SPIE. All rights reserved.
Accession Number: 20204909580442
Record 272 of

Title:Design and fabrication of dual-scale broadband antireflective structures on metal surfaces by using nanosecond and femtosecond lasers

Author(s):Lou, Rui(1,2,3); Zhang, Guodong(4); Li, Guangying(1); Li, Xuelong(4); Liu, Qing(5); Cheng, Guanghua(4)
Source: Micromachines Volume: 11 Issue: 1 DOI: 10.3390/mi11010020 Published: January 1, 2020
Abstract:Antireflective surfaces, with their great potential applications, have attracted tremendous attention and have been the subject of extensive research in recent years. However, due to the significant optical impedance mismatch between a metal surface and free space, it is still a challenging issue to realize ultralow reflectance on a metal surface. To address this issue, we propose a two-step strategy for constructing antireflective structures on a Ti-6Al-4V (TC4) surface using nanosecond and femtosecond pulsed lasers in combination. By controlling the parameters of the nanosecond laser, microgrooves are first scratched on the TC4 surface to reduce the interface reflection. Then, the femtosecond laser is focused onto the sample surface with orthogonal scanning to induce deep air holes and nanoscale structures, which eectively enhances the broadband absorption. The antireflection mechanism of the dual-scale structures is discussed regarding morphological characterization and hemispherical reflectance measurements. Finally, the modified sample surface covered with micro-nano hybrid structures is characterized by an average reflectance of 3.1% over the wavelengths ranging from 250 nm to 2250 nm. ? 2019 The Author(s).
Accession Number: 20200808192468
Record 273 of

Title:Reconstructing of embedded high-aspect-ratio nano-voids generated by ultrafast laser bessel beams

Author(s):Chen, Tianqu(1,2); Zhang, Guodong(3); Wang, Yishan(1); Li, Xuelong(3); Stoian, Razvan(4); Cheng, Guanghua(3)
Source: Micromachines Volume: 11 Issue: 7 DOI: 10.3390/mi11070671 Published: July 2020
Abstract:Ultrafast non-diffractive Bessel laser beams provide strong light confinement and show robust advantages for fabricating high-aspect-ratio nanoscale structures inside transparent materials. They take the form of nanoscale voids with typical diameters well below the wavelength and aspect ratio of more than 1000. Delivering 3D morphologies of such nanoscale voids is an important issue to evaluate the result for fabrication. However, the characterization of such laser-induced structures is a difficult task. Here, an accurate and time-saving tomography-like methodology is proposed and adopted for reconstructing the morphology of high-aspect-ratio nano-holes. The technique allows an accurate assertion of laser parameters and position on nano-structured features. The reconstructed configuration reveals that nanoholes morphologies have a close relationship with energy distribution in the focal region. It suggests that the configuration of micro-explosion can be controlled by laser energy deposition in the process of laser-matter interaction down to the nanoscale. ? 2020 by the authors.
Accession Number: 20203008975356
Record 274 of

Title:Broadband and dispersion-free reflective silver metasurfaces as half-wave plate and vortex-beam generator

Author(s):Zhang, Xiaodong(1,2,3); Kong, Depeng(1,2); Yuan, Yuan(1,2); Mei, Sen(1,2); wang, Lili(1,2); Wang, Guoxi(1,2)
Source: Optics Communications Volume: 465 Issue: DOI: 10.1016/j.optcom.2020.125561 Published: 15 June 2020
Abstract:Metasurfaces have attracted increasing interest in manipulation of polarization state due to optical response in sub-wavelength size. This paper presents an approach to design reflective silver metasurfaces and demonstrates that they can act as half-wave plate and vortex-beam generator with high performance in simulation, namely, polarization conversion efficiency is about 85% as half-wave plate and mode purity of vortex beam is greater than 80% as vortex-beam generator. The designed reflective metasurfaces comprise three layers. The top layer is composed of two elliptic silver sub-wavelength pillars assembled into L pattern and arranged into array distribution. The middle layer is a thin dielectric spacer (SiO2) and the bottom layer is silver ultrathin film. The metasurfaces have advantages of broadband (70～110 THz) and dispersion-free. The simulated results are also in good agreement with theoretical derivation. In addition, the separation between the reflective components makes the design more suitable for spatial mode multiplexing and may become a potential candidate in integrated optical communication system in future. ? 2020 Elsevier B.V.
Accession Number: 20201008263523
Record 275 of

Title:Design of concentric multiscale optical system for long-wave infrared band

Author(s):Shen, Yang(1); Wang, Hu(1); Xue, Yaoke(1); Liu, Meiying(1); Jie, Yongjie(1); Lin, Shangmin(1); Liu, Jie(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11567 Issue: DOI: 10.1117/12.2580270 Published: 2020
Abstract:With the development of optoelectronic imaging technology, remote sensing optical system gradually develops towards super large imaging field of view in order to obtain target characteristic information in a wider space. Concentric multiscale system is a new type of large field of view optical system. At present, most of the schemes studied are multiscale system based on concentric spherical lens. Due to the limitation of optical materials, this optical system is generally only used in visible and near infrared optical bands, and is difficult to be applied in long-wave infrared band. Starting from the structure principle of concentric multi-scale system and considering the application of long-wave infrared band, this paper proposes to use spherical reflector instead of concentric spherical lens to construct a retracted multi-scale system based on spherical reflector. The system can achieve all the features of multi-scale system and can be applied in the infrared band. According to the construction principle of the system and the design idea of off-axis deviation field, a multi-scale system based on spherical reflector is designed. The main parameters of the single channel of the system are: the focal length is 72mm, the system F=2, the working band is 8-12um, and the imaging field of view is 20*0.1. The imaging quality of the system is close to the diffraction limit in the full field of view, and the distortion of the full field of view is less than 5%. The circular field of view imaging of 360*0.1 can be achieved by extending the spherical reflector and multi-channel splicing. ? 2020 SPIE.
Accession Number: 20205009602468
Record 276 of

Title:Investigation on Smart Cushion Based on SFS Structure and its Application in Physiological and Activity Monitoring

Author(s):Han, Shuying(1); Xu, Wei(2,3); You, Shanhong(1); Dong, Bo(2,3,4); Tan, Fengze(5); Yu, Changyuan(6); Zhao, Wei(2,3,4); Wang, Yishan(2,3,4)
Source: 25th Opto-Electronics and Communications Conference, OECC 2020 Volume: Issue: DOI: 10.1109/OECC48412.2020.9273653 Published: October 4, 2020
Abstract:A smart cushion based on SFS (single-mode-few-mode-single-mode) structure is proposed and experimentally demonstrated, which can be applied in physiological and activity states monitoring simultaneously. The sensing unit embedded in a common cushion is designed as a sandwich structure, consisting of a piece of fiberglass mesh, a SFS structure layer and a polyvinyl chloride (PVC) layer thus the sensitivity can be significantly enhanced. With off-line processing and analyzing of the raw signals collected from the cushion system, the heartbeat rate (HR) and respiratory rate (RR) can be obtained with the maximum error of 1 bpm and the activity states on the cushion can be clearly distinguished within the accuracy of one second. Such a smart cushion has the advantages of low cost, compact structure and high comfort, especially suitable for office workers and the elderly in nursing homes. ? 2020 IEEE.
Accession Number: 20210109729358

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