2021
2021
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Record 193 of
Title:Simulation and analysis of the coherent-dispersion spectrometer for exoplanet detection
Author(s):Wu, Yinhua(1); Chen, Shasha(2,3); Wang, Pengchong(2,3); Zhou, Shun(1); Feng, Yutao(2,3); Zhang, Weiguang(1); Wei, Ruyi(2,3)Source: Monthly Notices of the Royal Astronomical Society Volume: 503 Issue: 2 DOI: 10.1093/mnras/stab656 Published: May 1, 2021Abstract:The coherent-dispersion spectrometer (CODES) is a new exoplanet detection instrument using the radial velocity (RV) method. This attempts mainly to improve environmental sensitivity and energy utilization by using an asymmetric, common-path Sagnac interferometer instead of a traditional Michelson interferometer. In order to verify its feasibility and to choose the appropriate key parameters to obtain the optimal performance, research on data processing for the design stage of the CODES is performed by systematic simulation and analysis. First, the instrument modelling is carried out for further data analysis according to the principle of the CODES, and the reliability of the model is verified by experiments. Second, the influence of key parameters on fringe visibility is analysed systematically, which provides a certain reference for the choice of the key parameters. Third, the RV inversion method for the CODES is proposed and optimized according to the related analysis results so as to promote RV inversion precision. Finally, the recommended values for the key parameters of the CODES are given. The experimental results show that the data processing error of RV inversion is less than 0.6 m s-1 within the recommended range of key parameters. This indicates that the scheme of the CODES is reasonable and feasible, and that the proposed data processing method is effective and well matched with the instrument design. ? 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical SocietyAccession Number: 20221712022157 -
Record 194 of
Title:Numerical study and improvement of the dynamic performance of dilation x-ray imager
Author(s):Wang, Qiangqiang(1); Cao, Zhurong(1); Chen, Tao(1); Deng, Bo(1); Deng, Keli(1); Tian, Jinshou(2)Source: Review of Scientific Instruments Volume: 92 Issue: 12 DOI: 10.1063/5.0061685 Published: December 1, 2021Abstract:We present in this Note a numerical study on the dynamic performance of a Dilation X-ray Imager (DIXI). The DIXI including a photoelectron tube (PT) and a magnetic solenoid is modeled in 3D space. The initial parameters of the photoelectrons are sampled with a Monte Carlo code. The trajectories of the photoelectrons are calculated by using the particle-in-cell method, and the transit time spread (TTS) and temporal magnification are analyzed in detail. We have designed a PT with a double-microstrip structure and compared the performance of the double-microstrip PT with the traditional single-microstrip PT. The results show that the sensitivity of the TTS and the temporal magnification to the emission time of the photoelectrons can be significantly reduced by using the double-microstrip PT, resulting in an improvement of the time window. Therefore, the dynamic performance of the DIXI is improved. ? 2021 Author(s).Accession Number: 20220211437002 -
Record 195 of
Title:Heart-Rate Monitoring with an Ethyl Alpha-Cyanoacrylate Based Fiber Fabry-Perot Sensor
Author(s):Li, Yang(1); Dong, Bo(1); Chen, Enqing(2); Wang, Xiaoli(2); Zhao, Yudi(2)Source: IEEE Journal of Selected Topics in Quantum Electronics Volume: 27 Issue: 4 DOI: 10.1109/JSTQE.2020.3002084 Published: July-August 2021Abstract:Heart-rate monitoring with an ethyl alpha-cyanoacrylate (EtCNA) based fiber Fabry-Perot (F-P) sensor is presented. The fiber F-P sensor is fixed in a capillary tube by using the EtCNA binder. Due to the lower Young's modulus of the EtCNA, the sensor can detect low frequency vibration with a high sensitivity. The fiber sensor is attached in a specially designed bracket to obtain the stable data. When the sensor with bracket is put on the human body, the heart-rate can be monitored accurately by monitoring the laser intensity variation induced by the heartbeat. Experimental results show that the sensor has the strain sensitivity of 2.57 pm/μN(yùn) with good responses to low frequency vibrations of 1 Hz, 2 Hz and 3 Hz. The maximum and the minimum mean square deviations of the volunteers' data are 4.434210 and 0.667499, respectively. Moreover, it has good adaptability to measure the heart-rate on different positions of human body, such as wrist, chest and neck. Due to the advantages of small size, low cost, good adaptability, pollution-free and no harm to body. Our proposed sensor is expected to be widely used in heart disease monitoring. ? 1995-2012 IEEE.Accession Number: 20202608862729 -
Record 196 of
Title:Design Method for Initial Structure of Freeform Surface Optical System
Author(s):Luo, Yue(1,2); Li, Libo(1); Feng, Yutao(1); Zhao, Hengxiang(1); Li, Xijie(1); Bai, Qinglan(1)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 41 Issue: 24 DOI: 10.3788/AOS202141.2422002 Published: December 25, 2021Abstract:A direct construction method for freeform surface optical system is proposed to address the problem that the initial structure is difficult to obtain in the design of such system. With the ideal object-image relationship and the Fermat principle as the criteria of single module iteration, an initial structure with favorable optimization potential can be directly obtained from a plane optical system without optical power by tracing light rays point by point. It can be solved faster by sampling feature light rays with different densities at different iteration stages. After the initial optical structure is obtained, optical design software can be used to further optimize the image quality. A compact off-axis two-mirror optical system with a 150 mm focal length and a physical size less than 40 mm×70 mm×60 mm is designed by the proposed method, which verifies the feasibility of this method in the design of freeform surface optical systems. ? 2021, Chinese Lasers Press. All right reserved.Accession Number: 20220911713503 -
Record 197 of
Title:Corrective method for spectral offset error caused by radial distortion in the large aperture static imaging spectrometer
Author(s):An, Ling-Ping(1,2); Wang, Shuang(1); Zhang, Geng(1); Li, Juan(1); Liu, Xue-Bin(1)Source: Chinese Optics Volume: 14 Issue: 2 DOI: 10.37188/CO.2020-0084 Published: March 2021Abstract:In order to improve the spectral calibration accuracy of the large aperture static imaging spectrometer when its field of view is increased, and to reduce the influence of radial distortion on its spectral accuracy, we propose a corrective method for spectral calibration coefficients based on a spectral distortion correlation model. To begin the process, the wave number and wavelength correction formulas are given. Using 594.1 nm and 632.8 nm gas lasers, a spectroscopic imaging experiment was performed on the imaging spectrometer, and the data was processed and analyzed. The results show that when there is a barrel distortion of 0.3%, the inversion spectrum at the edge of the field of view shifts approximately 2 nm. After implementing the corrective method of this paper, the line shift is reduced to approximately 0.1 nm. This method only needs to be corrected according to the lens distortion parameters, which simplifies the laboratory spectral calibration process and improves work efficiency. It can also be applied to the orbit parameter correction of spaceborne interference spectral data. Copyright ?2021 Chinese Optics. All rights reserved.Accession Number: 20211610236305 -
Record 198 of
Title:Smart Optic Fiber Mattress for Animal Sleep Continuous Monitoring Based Multi-Modal Interferometer
Author(s):Li, Yang(1); Dong, Bo(1); Zhao, Yudi(2); Chen, Enqing(2); Wang, Xiaoli(2); Zhao, Wei(1); Wang, Yishan(1)Source: Journal of Lightwave Technology Volume: 39 Issue: 12 DOI: 10.1109/JLT.2020.3048958 Published: June 15, 2021Abstract:A smart optic fiber mattress for animal sleep continuous monitoring based on a multi-modal interferometer is presented. The sensor is fabricated by splicing two single mode fibers (SMFs) and a multimode fiber (MMF) with a grid structure. Due to the network structure of the sensor, it has wider contact surface for monitoring vital signs and reduces the detection difficulty caused by the change of measured object position. The sensing unit can be placed under the dog mattress. Experimental results show that it can continuously monitor the sleeping activities and respiration of the dog. The detected information includes activity rhythm, sleeping state and sleeping respiratory rates (SRR). This technique avoids some potential problems such as injuring caused by the sensor appendage and dispute caused by moral principles. It is qualified to be widely used in health care of pets and protection of wildlife. ? 1983-2012 IEEE.Accession Number: 20210309771358 -
Record 199 of
Title:Soliton Burst and Bi-Directional Switching in the Platform with Positive Thermal-Refractive Coefficient Using an Auxiliary Laser
Author(s):Zhao, Yanjing(1,2); Chen, Liao(1); Zhang, Chi(1); Wang, Weiqiang(3,4); Hu, Hao(1); Wang, Ruolan(1); Wang, Xinyu(3,4); Chu, Sai T.(5); Little, Brent(3); Zhang, Wenfu(3,4); Zhang, Xinliang(1)Source: Laser and Photonics Reviews Volume: 15 Issue: 11 DOI: 10.1002/lpor.202100264 Published: November 2021Abstract:Dissipative Kerr solitons in optical microresonators enable the generation of stable ultrashort pulses and phase-locked frequency combs, leading to their widespread applications. For traditional platforms with positive thermal-refractive coefficient, strong thermal effect increases the difficulties of soliton triggering and prohibits the deterministic control of soliton number. Here, using an auxiliary laser to tune thermal effect, soliton burst and bi-directional switching are demonstrated in high-index doped silica glass platform. First, by varying the parameters of the auxiliary laser, the thermal effect tuning of the microresonator is studied with different thermal compensation states achieved, leading to distinct soliton switching features. Especially, the solitons burst and bi-directional switch in over-compensated state. The corresponding process is recorded in real time based on a temporal magnification system, uncovering transient dynamics from continuum background noise to soliton formation. Finally, the deterministic generation of solitons is enabled with controllable soliton number spanning from 1 to 21. The present work provides insight into soliton dynamics and enables soliton generation on demand with a large range of soliton numbers inside a single?device. ? 2021 Wiley-VCH GmbHAccession Number: 20213910934443 -
Record 200 of
Title:A Comprehensive Review of Fluorescence Correlation Spectroscopy
Author(s):Yu, Lan(1); Lei, Yunze(1); Ma, Ying(1); Liu, Min(1); Zheng, Juanjuan(1); Dan, Dan(2); Gao, Peng(1)Source: Frontiers in Physics Volume: 9 Issue: DOI: 10.3389/fphy.2021.644450 Published: April 12, 2021Abstract:Fluorescence correlation spectroscopy (FCS) is a powerful technique for quantification of molecular dynamics, and it has been widely applied in diverse fields, e.g., biomedicine, biophysics, and chemistry. By time-correlation of the fluorescence fluctuations induced by molecules diffusing through a focused light, FCS can quantitatively evaluate the concentration, diffusion coefficient, and interaction of the molecules in vitro or in vivo. In this review, the basic principle and implementation of FCS are introduced. Then, the advances of FCS variants are reviewed, covering dual-color FCCS, multi-focus FCS, pair correlation function (pCF), scanning FCS, focus-reduced FCS, SPIM-FCS, and inverse-FCS. Besides, the applications of FCS are demonstrated with the measurement of local concentration, hydrodynamic radius, diffusion coefficient, and the interaction of different molecules. Lastly, a discussion is given by summarizing the pros and cons of different FCS techniques, as well as the outlooks and perspectives of FCS. ? Copyright ? 2021 Yu, Lei, Ma, Liu, Zheng, Dan and Gao.Accession Number: 20233514653793 -
Record 201 of
Title:Investigation of the size of nanoparticles formed during femto- and nanosecond laser ablation of zircon
Author(s):Yang, Yong(1,2,3); Lou, Rui(1,3); Yuan, Honglin(4); Shu, Yiqing(5); Fan, Wenhui(1,3,6); Cheng, Guanghua(1,7); Si, Jinhai(2)Source: Optical Engineering Volume: 60 Issue: 8 DOI: 10.1117/1.OE.60.8.086108 Published: August 1, 2021Abstract:Laser ablation of zircon can be used to analyze its composition for geological history. However, the effect of laser properties on nanoparticle size has not been studied extensively. The effect of laser fluence and pulse duration on the diameter of zircon nanoparticles was analyzed using field-emission scanning electron microscopy and energy dispersive spectroscopy. The results showed that the diameters of the zircon nanoparticles induced by a femtosecond laser increased with increasing laser fluence, and that these particles were smaller than those induced by a nanosecond laser with the same laser fluence. Furthermore, the mechanism of zircon nanoparticle formation induced by laser ablation has been discussed. The explosion mechanism is the primary mechanism of nanoparticle generation. In particular, the zircon nanoparticles induced by the femtosecond laser were the result of Coulomb explosion, while phase explosion contributed to the zircon nanoparticles induced by the nanosecond laser. Therefore, the nature of zircon nanoparticles induced by laser ablation is mainly determined by the pulse duration. ? 2021 Society of Photo-Optical Instrumentation Engineers (SPIE).Accession Number: 20240315383380 -
Record 202 of
Title:Infrared and visible image fusion based on variational auto-encoder and infrared feature compensation
Author(s):Ren, Long(1,2,3); Pan, Zhibin(2); Cao, Jianzhong(1); Liao, Jiawen(1,2,3)Source: Infrared Physics and Technology Volume: 117 Issue: DOI: 10.1016/j.infrared.2021.103839 Published: September 2021Abstract:With high sensitivity to capture rich details, visible imaging equipment can take images containing more textures and contours which are important to visual perception. Unlike visible cameras, infrared imaging devices can detect targets invisible in visible images, because the imaging principle of infrared sensors derives from differences of thermal radiation. Thus, the purpose of image fusion is to merge as much meaningful feature information from the infrared and visible images into the fused image as possible, such as contours as well as textures of the visible image and thermal targets of the infrared image. In this paper, we propose an image fusion network based on variational auto-encoder (VAE), which performs the image fusion process in deep hidden layers. We divide the proposed network into image fusion network and infrared feature compensation network. Firstly, in the image fusion network, the encoder of the image fusion network is created to generate the latent vectors in hidden layers from the input visible image and infrared image. Secondly, two different latent vectors merge into one based on the product of Gaussian probability density; accordingly, the decoder begins to reconstruct the fused image with the descent of the loss function value. Meanwhile, Residual block and symmetric skip connection methods are added to the network to enhance the efficiency of network training. Finally, due to the defect of the loss function setting in the fusion network, an infrared feature compensation network is designed to compensate critical radiation features of the infrared image. Experimental results on public available datasets demonstrate that the proposed method is superior to other traditional and deep learning methods in both objective metrics and subjective visual perception. ? 2021Accession Number: 20213210748432 -
Record 203 of
Title:High-precision time-frequency signal simultaneous transfer system via a WDM-based fiber link
Author(s):Qi, Zang(1,2,3,5); Honglei, Quan(1,2,3); Kan, Zhao(1); Xiang, Zhang(1,2,3); Xue, Deng(1,2); Wenxiang, Xue(1,2); Faxi, Chen(4); Tao, Liu(1,2,3); Ruifang, Dong(1,2,3); Shougang, Zhang(1,2,3)Source: arXiv Volume: Issue: DOI: null Published: June 8, 2021Abstract:In this paper, we demonstrate a wavelength division multiplexing (WDM) based system for simultaneously delivering ultrastable optical frequency reference, 10 GHz microwave frequency reference, and one pulse per second (1 PPS) time signal via a 50 km fiber network. For each signal, a unique noise cancellation technique is used to maintain the precision of them. After being compensated, the transfer frequency instability in terms of overlapping Allan deviation (OADEV) for the optical frequency achieves 2×10-17/s and scales down to 2×-1020/10000 s, which for the 10 GHz microwave reference approaches 4×10-15/s and decreases to 1.4×10-17/10000 s, and the time uncertainty of the 1 PPS time signal along the system is 2.08 ps. In this scheme, specific channels of WDM are respectively occupied for different signals to avoid the possible crosstalk interference effect between the transmitted reference signals. To estimate the performance of the above scheme, independent of these signals is also demonstrated in this 50 km link, the results are similar to that in the case of simultaneous delivery. This work shows that the WDM-based system is a promising method for building a nationwide time and frequency fiber transfer system with a communication optical network. ? 2021, CC BY.Accession Number: 20210136429 -
Record 204 of
Title:Infrared and visible image fusion based on edge-preserving guided filter and infrared feature decomposition
Author(s):Ren, Long(1,2,3); Pan, Zhibin(2); Cao, Jianzhong(1); Zhang, Hui(1,3); Wang, Hao(1)Source: Signal Processing Volume: 186 Issue: DOI: 10.1016/j.sigpro.2021.108108 Published: September 2021Abstract:Infrared (IR) images can distinguish salient targets from their backgrounds based on the radiation difference in all-weather conditions. By contrast, visible (VIS) images can contain high-resolution texture and details information, which is more suitable for human observation. Therefore, it is quite necessary to combine both imaging advantages of these two kinds of images. Compared with the existing methods, we believe that scale decomposition based methods are the most active and efficient image fusion methods, which also have the best fusion effects. Inspired by the present scale decomposition methods, we propose a new feature decomposition method. Firstly, we propose an improved guided filter called edge-preserving guided filter (EPGF), which adopts the image gradient map for further improving the filtering effect. Subsequently, by using the EPGF, we decompose the IR and VIS images into three kinds of layers, including salient feature layers, luminance layers and detail layers. At the same time, we combine all the layers together to get an initial fusion result. Finally, we optimize the initial fusion image according to a new image fusion optimization model and ADMM, and the final fusion result will be obtained after several iterations. Compared with other scale decomposition methods, our proposed feature decomposition based method takes the IR salient targets, IR and VIS background illumination, as well as VIS details into consideration which is more in line with human visual observation, besides the computational efficiency is also superior. Experimental results indicate that this method has better subjective and objective evaluation results compared with other state-of-the-art methods. ? 2021 Elsevier B.V.Accession Number: 20211610223004