2019
2019
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Record 193 of
Title:An image telecentric optical system of low-distortion and wide-field
Author(s):Wang, Hu(1,2); Xue, Yaoke(1); Xiao, Nan(1,2); Liu, Jie(1); Liu, Meiying(1,2); Liu, Yang(1); Lin, Shangmin(1); Wang, Fang(1,2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10838 Issue: DOI: 10.1117/12.2505108 Published: 2019Abstract:In the final step of approaching and docking proximity of space rendezvous and docking, it is necessary to measure the relative position and posture of two spacecrafts with high precision using by optical imaging sensor. The image quality of the optical system itself of optical image sensor, to a great extent, will influence the accuracy of navigation information of rendezvous and docking, and even determine the success or failure of rendezvous and docking task. The image telecentric optical system, adopted by the multi-components and retrofocus structure and designed by the hyperfocal distance theory, not only can realize clear imaging from 2 meters to infinity, but also can make sure the center position of image that is imaged by the object from 2 meters to infinity basically invariant. It used the method of ;S type correction of distortion and corrected the distortion of edged field of view (FOV) and 0.8FOV synchronously, which realized the relative distortion less than 0.028%?1/4absolute distortion less than 0.78μm?1/4‰in the range of 30° fields of view, and met the requirements of the high precision of imaging system and illuminancy uniformity of different fields of view. ? 2019 COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.Accession Number: 20190506430684 -
Record 194 of
Title:Design of the front window of full-disc vector magnetograph
Author(s):Wang, Xingfeng(1,2); Li, Fu(1); Chen, Guoqing(1,2); Lv, Juan(1); Lu, Zhizhou(1,2); Yang, Jianfeng(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10837 Issue: DOI: 10.1117/12.2504797 Published: 2019Abstract:Full-disc vector magnetograph (FMG) is one of the main loads in the Advanced Space-based Solar Observatory. FMG is used to realize scientific goals of observing full-disk vector magnetic field with center wavelength of 532.4 nm. The optical system of FMG consists of polarized optical system and imaging optical system, and the imaging optical system composes of the front window and telescope system. The front window has the capability for providing proper situation for scientific observation by absorbing high energy of solar irradiance coming from space while reflecting wavelength of non-scientific investigation beyond wavelength of 532.4±5 nm. The study analyzed the influence of complex space environment on optical glasses. As a result, the material of fused silica, while two pieces of flat glass parallel with 3mm separation structure and thickness of 15mm are determined. Finally, the results show that design for the front window meet the required specifications. ? 2019 SPIE.Accession Number: 20190506432490 -
Record 195 of
Title:Heavy-calibre off-Axis aspheric surface polishing by industrial robot
Author(s):Yao, Yongsheng(1,2); Ma, Zhen(1); Ding, Jiaoteng(1); Chen, Qinfang(1); Fan, Xuewu(1); Shen, Le(1); Li, Qixin(1,2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10838 Issue: DOI: 10.1117/12.2504755 Published: 2019Abstract:An ABB IRB6640 industrial robot is used as a processing platform for optical polishing. The relationships of coordinate systems are defined, the algorithm of coordinate transformation, Euler angles and quaternion are provided. M-like removal function and Gaussian-like removal function are used to simulation process an off-Axis aspheric surface. The surface error after polishing by M-like removal function is 1.5 to 2.5 times bigger than Gaussian-like removal function. This proves that M-like removal function also has good convergence speed. Then, the pentagram polishing head is used to polish a Φ600mm off-Axis paraboloid surface. After 15 cycles, about 120 hours processing, PV converges from 5.8μm to 0.836μm, RMS converges from 1.2μm to 0.054μm, PV and RMS respectively converge 85% and 95%. The experiment shows M-like removal function has good convergence speed. ? 2019 COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.Accession Number: 20190506430091 -
Record 196 of
Title:Mechanical design of zoom optical system for deep space exploration
Author(s):Qian, Chongsen(1,2); Li, Fu(1); Yang, Jianfeng(1); Sun, Yi(1,2); Yang, Wenqiang(1,2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10837 Issue: DOI: 10.1117/12.2504761 Published: 2019Abstract:As one of the largest aerospace countries in the world, China's National Space Administration has officially launched the China Mars Exploration Project in 2016. The zoom lens, in contrast to a fixed focal length lens, has a continuously variable focal length that provides more intuitive information for probing activities. Therefore, it is particularly important to design a zoom lens and use it as a Mars probe imaging payload. In this paper, a zoom system is designed for the climatic environment of Mars and the condition requirements of the lander during transportation work. At the same time, different types of structures were discussed. Finally, a cam rotation mechanism was used in the zoom mechanism. Examining the complexity of the space thermal environment, the thermal characteristics of the system structure will have a great impact on the system performance. To prevent the adverse effects of different thermal expansion coefficients on the system over a wide operating temperature range, select the appropriate materials and the overall structure It is very important to carry out finite element analysis. In this paper, thermal deformation analysis of Aluminum Alloys, Titanium Alloys and Invar Steel materials was performed. The results show that the thermal deformation of Aluminum Alloy materials is maximum at the working temperature of -55°C to +55°C, the thermal deformation of the Aluminum Alloy material is the largest, and the titanium alloy and Invar Steel are relatively small. Finally, the axial displacement is analyzed. The analysis results show that Invar Steel material has the smallest axial displacement. However, considering the weight reduction, it has met the rocket launch requirements. Finally, titanium alloy material is used as the system structural material, and the cam curve is compensated according to the axial displacement. ? 2019 SPIE.Accession Number: 20190506432481 -
Record 197 of
Title:Improved vector extrapolation based Richardson-Lucy algorithm used for wavefront coded imaging and experimental demonstration
Author(s):Zhao, Hui(1); Xia, Jingjing(1,2); Zhang, Ling(1,2); Yu, Congcong(1,2); Fan, Xuewu(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11062 Issue: DOI: 10.1117/12.2525721 Published: 2019Abstract:Wave-front coding is a mile-stone technique that can be used to greatly extend the DOF (depth of field) of incoherent imaging system. Besides the phase mask design, the digital restoration is very crucial to obtain clear image with largely extended DOF. Richardson-Lucy (RL) algorithm is a kind of nonlinear image restoration method which is based on Poisson noise model and maximum likelihood estimation. Because RL algorithm can generate high quality restoration result and own the capability to realize super-resolution construction, it has been widely applied in the field of astronomy, macroscopic imaging and et.al. However, classical RL algorithm converges very slowly and have to be run many times to achieve an acceptable restoration result when it is applied to wave-front coded imaging system whose point spread function has quite a large support region. Our previously published results demonstrate that at least 60 times iterations are needed for each color channel, which severely prohibits real-time implementation of classical RL algorithm. Therefore in this manuscript, an improved vector extrapolation based RL algorithm is designed by embedding the modified exponent into the framework of traditional vector extrapolation based RL algorithm. Not only a bigger iteration step indicating a bigger acceleration ratio is obtained, but also the noise amplification is effectively prohibited. Experimental results demonstrate that with the same number of iterations, the restored image corresponding to the improved vector extrapolation based RL algorithm has a better visual quality. At the same time, the structural similarity index (SSIM) is used as a criterion to determine the optimum iterations for each color channel and optimum combinations of algorithm parameters, based on which total iterations for color images are reduced approxiamately 78.9% and visually satisfactory restoration results can be obtained without denoising the restored image further. It could be considered that the work reported in this manuscript paves the way for realization of the embedded processing based real-time wave-front coded imaging in the future. ? COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.Accession Number: 20194407611681 -
Record 198 of
Title:Research on influences of atmospheric turbulence on long-distance Fourier ptychographic imaging
Author(s):Yang, Mingyang(1,2); Fan, Xuewu(1); Zhao, Hui(1); Li, Chuang(1); Xiang, Meng(1,2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11062 Issue: DOI: 10.1117/12.2525716 Published: 2019Abstract:Fourier ptychography (FP) has emerged as a powerful tool to improve spatial resolution. In order to apply FP technique to long-distance imaging for example remote sensing, many factors have to be overcome, such as diffraction, noise, turbulence and so on. In this paper, we mainly aims at studying the influence of atmospheric turbulence on FP technique, and using iterative algorithms to restore high-legible image and eliminating the residual errors, so it will meet or reach the diffraction limit of imaging system. The optical imaging systems which work in atmospheric circumstance will face the problem of imaging through atmospheric turbulence, which causing the blurring of image and badly impact the imaging capability of optical systems. We combine the FP with the theory of adaptive optics to achieve the effective recovery of the long-range target, which is subject to the effect of atmospheric turbulence. In this work, we firstly introduce a Fourier Series (FS) atmospheric phase screen generator to simulate the atmospheric-induced wave front phase distortions and represent the wave front phase as a two dimensional periodic function. Both the spatial and temporal correlations between wave-front phase screens separated by time and/or angle are properly modeled. And using the adaptive optics we complete the correction of the atmospheric turbulence in large distance imaging through the developed algorithm. Then we propose using laser arrays coupled with coherent illumination as an effective method of improving spatial resolution in long distance images. We emulate a laser arrays realized by optical fiber conduction and also show that appropriate phase retrieval based reconstruction algorithm which can be used to effectively recover the lost high resolution details from the multiple low resolution acquired images. Finally we analyze the effects of the atmospheric turbulence on the reconstructed image quality. The results prove that under the influence of atmospheric turbulence at outer scale of 1-m, inner scale of 0.1-m, Fourier ptychographic reconstruction can obtain good image quality for object 200 meters far away. The spatial resolution is increased six-fold. ? COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.Accession Number: 20194407611670 -
Record 199 of
Title:Research on an accurate heart rate extraction method based on image sequence
Author(s):Yu, Jiang-Jun(1,2); Zhou, Liang(1); Liu, Zhao-Hui(1)Source: IOP Conference Series: Earth and Environmental Science Volume: 332 Issue: 3 DOI: 10.1088/1755-1315/332/3/032011 Published: November 5, 2019Abstract:We had collected the video frame of people's index finger by the smart phone, and then extracted the human's pulse signal by analyzing the sequence images. When the original signal exists serious noise interference, the traditional heart rate detection algorithm is not applicable. Therefore, we proposed a heart rate extraction algorithm based on K-means clustering algorithm and dynamic image sequence, which can effectively extract heart rate information under the condition of strong noise. Finally, we used Bland-Altman analysis method to evaluate the accuracy of the algorithm, and the experimental result shows that it's in good agreement with the professional measuring instrument. ? Published under licence by IOP Publishing Ltd.Accession Number: 20194907781071 -
Record 200 of
Title:The application of active polarization imaging technology of the vehicle theodolite
Author(s):Xie, Meilin(1,2); Ma, Caiwen(1); Liu, Kai(1); Liu, Peng(1,2); Hao, Wei(1); Han, Junfeng(1); Huang, Wei(1); Lian, Xuezheng(1); Feng, Xubin(1,2); Jing, Feng(1)Source: Optics Communications Volume: 433 Issue: DOI: 10.1016/j.optcom.2018.09.056 Published: 15 February 2019Abstract:The vehicle theodolite has been the trend of the optical shooting range survey. While tracking and imaging of the long-distance dim targets have not been solved perfectly in this field, so this paper presents one active polarization imaging technology to find a way to deal with it. Firstly, we put forward a new active polarization imaging system with the lighting mode of circularly polarized laser and receives the reflected light by the mode of range-gating technique; secondly, deduces the pulse laser beam pointing algorithm; thirdly, describes the extended Kalman filtering algorithm to compensate the delay in the process and the calculation of the polarization angle, the attitude angle of flight target using single station cosine method and the depolarization of the circularly polarized laser. Finally, the result of this active polarization imaging technology which is simulated and analyzed in Simulink shows that the pointing precision can reach 0.0075 degrees. Then the analysis in this paper provide a theoretical basis for the application of the active polarization imaging technology in the field of the optical shooting range survey. ? 2018 Elsevier B.V.Accession Number: 20184205955842 -
Record 201 of
Title:Optical design of all-day star sensor
Author(s):Xiao, Nan(1,2); Wang, Hu(1,2); Shen, Yang(1,2); Pan, Yue(1,2); Wang, Fang(1,2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10838 Issue: DOI: 10.1117/12.2504892 Published: 2019Abstract:The star sensor is used to detect the position of the stars in space. By recognizing and analyzing star maps, satellites or spacecraft can automatically change the direction of movements to realize the navigation function. However, the strong background radiation in the sky during the day results in a low contrast of the star image. This brings great difficulties to star sensors that work on atmospheric platforms observing stars all the time. To overcome the adverse impacts of the stray lights from the sky during the whole day through the atmosphere, a catadioptric all-day star sensor optical system is presented. In comparison to Cassegrain System, the design has a smaller size of aperture of housing. Therefore, it has the advantage of superb suppression of the stray lights caused by external sky background radiation and other factors. By adopting a plane mirror to compress the light path, the size of the system is decreased, realizing a light and miniaturized design. Based on the analysis of the characteristics of sky background radiation and star radiation, the optical system parameters are selected. The system has a focal length of 800mm, an effective aperture of 70mm, and an instantaneous field of view of 2 °. Meanwhile, with a steering mirror, it can observe an area between 40° and 70° airspace at all day. Finally, the results of the analysis show that the optical system spot shape approaches to a circle in the wide spectrum of 800 nm ～ 1700 nm, and the energy of which is close to the Gaussian distribution and highly concentrated. The modulation transfer function curve is close to the diffraction limit with small chromatic aberration of magnification. ? 2019 COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.Accession Number: 20190506430669 -
Record 202 of
Title:Optimized design of high-flux 2D magneto-optical trapping
Author(s):Song, Wei(1,2); Jia, Sen(1); Wang, Xianhua(1); Wu, Cuigang(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10839 Issue: DOI: 10.1117/12.2506119 Published: 2019Abstract:High-precision cold atomic interferometry requires a large flux of cold atomic groups, the length of 2D-MOT largely influences the number of cold atomic clusters in the 3D-MOT flux.The longer the 2D-MOT length, the longer the interaction of the atoms with the light field, so that the trajectory of the atom impinges on the inlet of the differential pump tube so that its divergence is small enough to reach the tube, but the length of 2D-MOT is not the longer,the better.There are two reasons for this: first, higher atomic flux and faster atoms are trapped as the length of 2D-MOT increases, resulting in an increase in the number of collisions between lateral radicals.Second, the average speed in the atomic beam increases.Above an optimum MOT length every increase in length will only add faster atoms to the beam, thus increasing the value for the mean velocity.In summary, choosing the best 2D-MOT length plays a key role in getting the number of cold radicals entering 3D-MOT.In this paper, through mathematical modeling and finite element analysis,2D-MOT race-track anti-Helmholtz coils are numerically calculated.Analyzing the distribution of zero magnetic field for coils of different lengths and zero drift and magnetic field gradient changes caused by the error of asymmetrical coil position, the number of uniform turns and parallelism in the process of processing and assembly.The result provides reliable theoretical guidance for the design and manufacture of the magnetic field system of 2D-MOT high-precision cold-atom interferometers. ? 2019 SPIE.Accession Number: 20190706488945 -
Record 203 of
Title:Research on the optical system of single-band all-sky airglow imager
Author(s):Li, Zhantao(1,2); Han, Bin(1,2); Xiao, Yang(1,2); Yu, Tingting(1,2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10841 Issue: DOI: 10.1117/12.2504967 Published: 2019Abstract:The middle and upper atmosphere is an important part of atmosphere of the earth. In this region, there are many photochemical phenomena and dynamical processes. One of the photochemical phenomena is airglow. When excited atmospheric molecule or atom transmits to lower level, the light with some wavelength will emit. The light is referred to as airglow. Airglow is therefore a powerful tool in investigations of atmospheric composition, temperature, and density in the emission region, and mass and energy movements to or from this region. Tracing the airglow emission, all-sky airglow imagers are widely used for imaging the atmospheric airglow. The characters of the imager are: wide field of view, fast, high resolution, low cost. This paper systematically studies the basic principle of the imager, completes the calculation of the key parameters, designs the optical system structure of the imager and optimizes the system image quality to obtain an ideal design result. The main contents can be list as follow. All-sky imaging technology records the optical phenomena in the 180° range above the ground plane with imaging and storage media. Use the fisheye lens to realize the 180° of the field of view. Different airglow layers correspond to different radiation peak heights. In order to obtain the atmospheric airglow signal at a certain height, it is necessary to filter the airglow radiation of different bands. The intensity of airglow information using narrow-band filter extraction feature height region of the upper atmosphere. High-sensitivity CCD were used to record all-sky airglow intensity distributions. The system consists of fisheye lens, telecentric imaging lens, filter, imaging lens and CCD. Through the analysis of recorded images, obtained observation data of regional atmospheric fluctuations of airglow height. The central wavelength of the imaging system is 630.5 nm, the bandwidth is 2 nm, the field of view is 180° the focal length is 5 mm, and the relative aperture is 1:1.9; The modulation transfers function (MTF) is more than 0.75 at the Nyquist spatial frequency of 37 lp/mm. The root-mean-square (RMS) radius of spot diagram is less than half of the pixel. 80% of the energy is enclosed in a pixel, and the uniformity of image illumination is 89%. The design requirements are satisfied. And based on the final design, the lens is simplified and the glass material is simplified. Finally, optimization of tolerance analysis is used to guide actual production. The final system structure compact, low cost, high resolution, suitable for airglow atmospheric radiation detection. ? 2019 SPIE.Accession Number: 20190706489092 -
Record 204 of
Title:Remote sensing image fusion algorithm based on à trous wavelet transform and HIS transform
Author(s):Xin, Hongqiang(1); Feng, Liangjie(2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11179 Issue: DOI: 10.1117/12.2539667 Published: 2019Abstract:The image fusion of optical images and synthetic aperture radar (SAR) images are of great significance. By using the complementary advantages of both, the target detection and recognition can be relatively simple and the accuracy will be relatively improved. The image information reflected by the optical image and the SAR image is very different, and the image fusion can combine the two information to give greater advantages. Aiming at the limitations of single sensor in terms of spectrum and spatial resolution, the multi-source sensor fusion technology can maximize the information description of the target scene. The fusion experiment and evaluation of optical images and SAR images are carried out by combining àtrous wavelet transform and IHS transform, and compared with the traditional HIS transform and wavelet transform fusion methods. The results show that the fusion of àtrous wavelet and HIS transform is the best, and the advantages of two single fusion methods are absorbed. It not only improves the spatial detail expression of the original image, but also preserves the spectral information of the original image, providing more accurate data for remote sensing applications. ? COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.Accession Number: 20193907475146