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Record 217 of
Title:A method of real-time monitoring the cyanobacterial bloom in inland waters based on ground-based multi-spectral imaging
Author(s):Yu, Jirui(1,2); Xue, Bin(1); Tao, Jinyou(1); Liu, Shengrun(1,2); Ruan, Ping(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11337 Issue: DOI: 10.1117/12.2547283 Published: 2019
Abstract:For the demand of inland water quality monitoring, a ground-based multi-spectral imaging method has been developed. By means of developing an instrument which can gather the multi-spectral data of the waterbody, the method can be used for real-time monitoring the contamination of inland waters, such as cyanobacteria bloom and phytoplankton. The research is focused on the technology of high-resolution multi-spectral data extraction and the theory of contaminant inversion model. Four branches of light beams of simple spectrum are obtained with spectral filters and are recorded by four groups of lens and detectors respectively. The four interested wavelength is chosen as 565 nm, 620 nm, 660 nm, 750 nm, according to the typical reflection peaks and dips of the contamination with a spectral resolution of 15 nm. The optical design features a field of view of 25.2×19.3 degree with a 16mm focal lens. The camera's resolution is 1628×1236 with the pixel size of 4.4 microns that reaches the spatial resolution of 0.945 arc min. The multi-spectral image is obtained through out-door experiments by monitoring the inland lake-Dianchi at a distance of 5 kilometers. After data revision, we can identify the constituent of the underwater contaminant and explain the pollution situation of cyanobacteria bloom in a certain period quantitatively. The inversion and extraction accuracy can reach at least 85%. And the long-term observation can explore the seasonal pattern of cyanobacteria bloom outbreak. ? 2019 SPIE.
Accession Number: 20200408062484
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Record 218 of
Title:Design of optical system for micro multispectral camera
Author(s):Liu, Yuzhe(1,2); Xue, Bin(1); Zhao, Yiyi(1); Chen, Guoqing(1,2)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11337 Issue: DOI: 10.1117/12.2547290 Published: 2019
Abstract:Aiming at the complex structure, difficult installation and high cost of the multispectral camera optical system used for phenological observation, a miniaturized and snapshot multispectral camera scheme is proposed. A compact and multi-channel image parallel optical system is designed by using a four-sided pyramid prism as an important optical element. The field-of-view of the system is ±3°, the working band is 400nm-600nm, the focal length is 50mm, and the F number is 5. The design results show that the single wavelength modulation transfer functions (MTF) at Nyquist frequency is better than 0.5, the root mean square radius (RMS) of all field of view is less than 7.4μm, and the distortion is less than 0.5%, which can meet the design requirements of multispectral cameras. ? 2019 SPIE.
Accession Number: 20200408062485
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Record 219 of
Title:Structure optimization of carbon fiber reflective mirror by response surface
Author(s):Song, Yang(1); Xu, Liang(1); Ma, Zhen(1); DIng, Jiaoteng(1,2)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11341 Issue: DOI: 10.1117/12.2539274 Published: 2019
Abstract:Space telescope is widely used nowadays. Reflective mirror is an important part of the space telescope. Many engineers are trying their best to make the reflective mirror lighter and lighter. Carbon fiber composite material is universally used in the field of aerospace. But there is little engineering experience about making a reflective mirror from carbon fiber. This paper will make a structure optimization about reflective mirror which is made of carbon fiber. Traditional way of structure optimization will call numerical simulation software for many times before finding the best solution. This paper uses a black box model to take the place of simulation software to do the optimization. The black box in this paper is response surface. To some extent, it is a simple type of machine learning. The response surface learns some key information and characteristics from the model which is made by simulation software. Then, the black box, response surface, can work like simulation software. The paper makes a structure optimization based on a certain kind of carbon fiber reflective mirror by the response surface. The diameter of reflective mirror which needs to be optimized in the paper is 150mm. The optimization variables are the thickness of carbon fiber plate and the position of supports. The purpose of the optimization is that the reflective mirror has small value of PV, proper fundamental frequency, small value of stress. The paper finds the best structure design at last by the method stated above. This kind of method can be used to make optimization about other similar optical structure. ? 2019 SPIE.
Accession Number: 20200408063320
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Record 220 of
Title:Optical design of long transmission type ultraviolet detection system
Author(s):Wang, Yuming(1,2); Fan, Xuewu(1); Ni, Dongwei(1,2); Wang, Lei(1,2)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10837 Issue: DOI: 10.1117/12.2504873 Published: 2019
Abstract:Ultraviolet (UV) detection and imaging technology has developed rapidly in military applications due to its simple environment and clean background. Especially in the ultraviolet communication, UV alarm, UV detection and UV guidance has a unique advantage. A medium telephoto transmission type UV optical system was designed using optical software. This system consisting of two aspheric surfaces and one binary diffractive surface and the other 10 spherical surfaces is adopted to realize the long-wavelength infrared image design parameters: UV operating waveband of 240- 300nm, focal length of 200mm, field of view (FOV) of 24.8 degree, the F number of 2, and total length of 210mm. By optimizing materials and distributing power properly the system characteristics have been greatly improved. After optimization, the MTF is higher than 0.7 at the 20lp/mm and the maximum RMS radius is only about 10 μm, which is much smaller than pixel size of the detector whose pixel size is 13.5μm×13.5μm. The energy concentration in UV CCD receiving surface is greater than 82%. Under the premise that the system meets the UV warning and detection optical properties, the use of aspheric surfaces reduces aberrations, simplifies the structure. This system has high imaging quality and simple structure. In terms of warning, it has good concealment, small size and light weight advantages. ? 2019 SPIE.
Accession Number: 20190506432482
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Record 221 of
Title:Fabrication and characterization of a polymeric curved compound eye
Author(s):Wang, Yuanyuan(1,2); Shi, Chengyong(1); Liu, Chenyang(1,2); Yu, Xiaodan(1,3); Xu, Huangrong(1,3); Wang, Taisheng(1); Qiao, Yanfeng(1); Yu, Weixing(3)
Source: Journal of Micromechanics and Microengineering Volume: 29 Issue: 5 DOI: 10.1088/1361-6439/ab0e9f Published: April 4, 2019
Abstract:Curved compound eyes, i.e. microlens arrays on curved surfaces, are highly desirable for their unique optical properties including wide field of view, tracking of fast moving objects and so on. However, it is technically challenging to fabricate biomimetic gapless microlens arrays. In this work, we report a simple method for fabricating close-packed microlenses in a kind of stretchable polymeric material PDMS on curved surfaces inspired by the vertebrate eyes. The successfully fabricated polymeric curved compound eye consists of more than 6000 close-packed ommatidia with an average diameter of 600 μm for each ommatidium. The ommatidia are located on a convex surface with a diameter of 40 mm and thus a total field of view of about 180 has been obtained. The optical test on ommatidia shows that the NA for each ommatidium is about 0.21 and the imaging result of the whole compound eye is also given. Furthermore, an optical relay system is introduced to integrate with the compound eye to form a biomimetic compound eye camera. The formed camera is shown to have a great potential for a broad range of optical imaging applications, such as surveillance imaging, target detection and tracking, surveying and mapping, collision-free navigation of terrestrial and aerospace vehicles. ? 2019 IOP Publishing Ltd.
Accession Number: 20192106955526
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Record 222 of
Title:Influence of energy fluence and overlapping rate of femtosecond laser on surface roughness of Ti-6Al-4V
Author(s):Yang, Yong(1,2,3); Lou, Rui(1,2); Chen, Xu(1); Fan, Wenhui(1,4); Bai, Jing(1); Cao, Weiwei(1); Cheng, Guanghua(1); Si, Jinhai(2)
Source: Optical Engineering Volume: 58 Issue: 10 DOI: 10.1117/1.OE.58.10.106107 Published: October 1, 2019
Abstract:The Ti-6Al-4V polished by femtosecond laser processing is first investigated. The surface nanoparticles of Ti-6Al-4V induced by femtosecond laser have been characterized by scanning electron microscopy and energy dispersive spectrometry, and the influence of laser fluence and the overlapping rate of laser beam on surface roughness have also been analyzed. Moreover, the relationship between the laser parameters and the surface roughness of Ti-6Al-4V has been revealed, and the fine surface roughness of Ti-6Al-4V is obtained based on the optimized femtosecond laser processing parameters. ? The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.
Accession Number: 20194507646279
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Record 223 of
Title:Femtosecond streak tube with large work area and small size for 3D imaging lidar
Author(s):Liu, Rong(1); Tian, Jinshou(2); Hui, Dandan(2); Xue, Qihang(1); Zheng, Kaiwen(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11209 Issue: DOI: 10.1117/12.2550180 Published: 2019
Abstract:Owing to the characteristics of high frame frequency, large field of view, small size, streak tube with large work area and small size has been the essential component of the streak tube imaging lidar, and has immense potential in the field of aerospace, space exploration and underwater detection. In this paper, streak tube with a large spherically curved photocathode and small size has been modeled and simulated. The static temporal resolution reaches to 633fs when the effective working diameter of photocathode is 28mm, and its magnification of the image is 1.4. The quantitative relationship between the curvature radius and temporal distortion is analyzed, and temporal distortion can be compensated to minimum when curvature radium R=45mm. Guidance is provided for developing a femtosecond streak tube with large work area and small size for 3D imaging lidar. ? 2019 SPIE.
Accession Number: 20200508093427
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Record 224 of
Title:Athermalization optical design of dual-wavelength infrared optical system with double-layer harmonic elements
Author(s):Kang, Fuzeng(1,2); Fan, Yangyu(1); Lv, Guoyun(1); Gao, Yongshen(1); Wang, Hao(2); Li, Yichao(2)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11052 Issue: DOI: 10.1117/12.2521909 Published: 2019
Abstract:A mathematical model of the diffraction efficiency change with the ambient temperature for the double-layer harmonic diffractive elements (HDE) is presented, and its effects are analyzed in this paper. The double-layer HDE structure is investigated and the optimization procedure is based on the equation of diffraction efficiency of the double-layer HDEs. By selecting appropriate design wavelength, the average diffraction efficiency of the system is reaching 99% in working wavelength and working temperature, which improves the image contrast and the image quality significantly. A set of dual-wavelength infrared optical system is designed based on dual-wavelength 320x240 element cooled thermal IR focal plane arrays detector. By introducing double-layer HDEs and aspheric surfaces, the chromatic aberration and the off-axis aberration are well corrected and the system structure is simplified. The system working in the wave band of 3.7～4.8μm and 7.7～9.5μm and with the F number of 2 is consisted of 8 elements and has 100% cold shield efficiency. The image quality evaluating results show that the performance of the dual-wavelength infrared optical system is very well in temperature from-40C° to +60C°. ? 2019 SPIE.
Accession Number: 20190806535051
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Record 225 of
Title:Optimization design and performance test of optical antenna for laser communication
Author(s):Zhao, Dongge(1,2); Ma, Xiaolong(1); Yang, Jianfeng(1); Chen, Guoqing(1,2)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10840 Issue: DOI: 10.1117/12.2506592 Published: 2019
Abstract:Laser communication has many outstanding advantages, such as high optical gain, high anti-interception, high anti-interference ability and high communication rate, it is an important technical method to solve the problem of high speed communication. The optical antenna is responsible for the reception and transmission of the signal, which is an important part of the laser communication terminal. Based on the general research situation at home and abroad, from the aspect of system SNR and efficiency, this article has determined some targets such as receiving / emission efficiency, wave aberration and ability of off-Axis stray light suppression; combined with specific application requirements, we have determined the basic parameters such as communication wavelength: 1545nm, aperture: 100mm, FOV: 0.1 degrees, optical magnification: 15 times. According to the above parameters, a set of reasonable optical antenna system has been designed and the test equipment is set up to measure, the test results are all satisfied. This paper has some reference value for the design and test of laser communication optical antenna. ? 2019 SPIE.
Accession Number: 20190706497364
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Record 226 of
Title:Detection of Dental Root Fractures Based on Endoscopic Swept Source Optical Coherence Tomography
Author(s):Sun, Wei(1,2); Li, Jianan(1); Qi, Liyuan(3); Zhu, Rui(1,4); Liang, Yuhong(3,5); Mi, Lei(1)
Source: Guangxue Xuebao/Acta Optica Sinica Volume: 39 Issue: 8 DOI: 10.3788/AOS201939.0811002 Published: August 10, 2019
Abstract:The diagnosis and treatment of root fractures are difficult issues in dentistry. A three-dimensional swept source optical coherence tomography (OCT) system was constructed. Utilizing cardiovascular endoscopic imaging catheter, we imaged 46 root section samples with root fractures(width ranges from 8 μm to 283 μm). The results show that the system has a diagnostic accuracy as good as 98.3% when the width of root fractures is greater than 30 μm. The diagnostic accuracy is 36.3% for fractures smaller than 30 μm. For the 25 fracture-free samples, the accuracy is 92%. Further analysis suggests optimization of the relative position and angle between the catheter and sample sections, as well as 3D reconstruction of images. These improvements achieve 100% accuracy for above-30 μm fractures and 57.6% accuracy for below-30 μm ones. This experiment suggests a promising future for the application of endoscopic OCT in the diagnosis of dental root fractures. ? 2019, Chinese Lasers Press. All right reserved.
Accession Number: 20193607409755
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Record 227 of
Title:Progress in Research and Applications of Plastic Optical Fiber
Author(s):Kong, De-Peng(1); Zhang, Da-Ming(2); Yuan, Yuan(1,3); Mu, Qi-Yuan(1,3); Mei, Sen(1,3); Xue, Lu(4); Wang, Li-Li(1)
Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 48 Issue: 11 DOI: 10.3788/gzxb20194811.1148006 Published: November 1, 2019
Abstract:Plastic optical fibers have the characteristics of lightweight, softness, low cost and so on. It is noteworthy that plastic optical fibers and other types of fibers have complementary advantages in function, then various plastic optical fibers can be applied in communication, image transmission, illumination, and decorative respectively to realize different functions. In the field of communication, graded index plastic optical fibers have obtained the transmission rate of 10 Gbps@100m in the consumption level, and 40 Gbps in the test level. In the field of image transmission, there are image bundles with 0.45 mm diameter@7 400 pixels and 1.5 mm diameter@13 000 pixels, as well as optical fiber plate products with resolutions up to 256 lp/mm. In the field of plastic optical fiber lasers, the theoretical and experimental research on the relationship between the parameters (gain medium, fiber length, fiber structure) and the characteristics of laser/amplifier is gradually deepening. In the field of decoration and illumination, lots of devices have been developed such as solar optical plastic optical fiber illumination, modeling plastic optical fiber illumination and plastic optical fiber blanket therapeutic instrument. In this paper, the latest researches and applications of plastic optical fiber mentioned above are reviewed. ? 2019, Science Press. All right reserved.
Accession Number: 20195307948347
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Record 228 of
Title:Single photon imaging Lidar using three Geiger-mode avalanche diodes
Author(s):Zhang, Zhenyang(1,2); Ma, Caiwen(1); Su, Xiuqin(1); Chen, Songmao(1,2); Wang, Shuchao(1,2); Zhu, Wenhua(1,2)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11338 Issue: DOI: 10.1117/12.2547913 Published: 2019
Abstract:In this paper, based on the principle that signals only occurs on a few time-bins (timing accuracy of a modern TCSPC module) due to short period illumination and the noise which is almost a constant for all bins, we designed an algorithm for denoising by using signals from multiple detectors and further improving the performance by adopting signal processing technique (e.g. median filtering). To exploit the information from the histograms efficiently, it is necessary to choose the gating width in an appropriate range, so that a well-placed window is large enough to capture most of signals, but without accepting too many noise. Whether to accept the signal is determined by weighting signals from multi-detectors within each gate width, where only multiple detections are recorded during the period can be accepted, otherwise detection is considered as noise and removed in the final reconstruction. Thus the three-dimensional information (the twodimensional spatial information and the depth information) of the target can be obtained accurately. In the algorithm, the results are evaluated numerically by signal to reconstruction error (SRE). The advantage is learned by comparing with several classic methods, the data used in this paper are derived from a mathematical model which account for Poisson statistics and Lidar equation. ? 2019 copyright SPIE. Downloading of the abstract is permitted for personal use only.
Accession Number: 20200308056219
