2016

• Record 337 of
  
  Title:Method used to test the imaging consistency of binocular camera's left-right optical system
  
  Author(s):Liu, Meiying(1); Wang, Hu(1); Liu, Jie(1); Xue, Yaoke(1); Yang, Shaodong(1); Zhao, Hui(1)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 9684  Issue:   DOI: 10.1117/12.2242265  Published: 2016  
  Abstract:To binocular camera, the consistency of optical parameters of the left and the right optical system is an important factor that will influence the overall imaging consistency. In conventional testing procedure of optical system, there lacks specifications suitable for evaluating imaging consistency. In this paper, considering the special requirements of binocular optical imaging system, a method used to measure the imaging consistency of binocular camera is presented. Based on this method, a measurement system which is composed of an integrating sphere, a rotary table and a CMOS camera has been established. First, let the left and the right optical system capture images in normal exposure time under the same condition. Second, a contour image is obtained based on the multiple threshold segmentation result and the boundary is determined using the slope of contour lines near the pseudo-contour line. Third, the constraint of gray level based on the corresponding coordinates of left-right images is established and the imaging consistency could be evaluated through standard deviation σ of the imaging grayscale difference D (x, y) between the left and right optical system. The experiments demonstrate that the method is suitable for carrying out the imaging consistency testing for binocular camera. When the standard deviation 3σ distribution of imaging gray difference D (x, y) between the left and right optical system of the binocular camera does not exceed 5%, it is believed that the design requirements have been achieved. This method could be used effectively and paves the way for the imaging consistency testing of the binocular camera. © 2016 SPIE.
  Accession Number: 20165003113955
• Record 338 of
  
  Title:Principal Component 2-D Long Short-Term Memory for Font Recognition on Single Chinese Characters
  
  Author(s):Tao, Dapeng(1); Lin, Xu(2); Jin, Lianwen(2); Li, Xuelong(3)
  Source: IEEE Transactions on Cybernetics  Volume: 46  Issue: 3  DOI: 10.1109/TCYB.2015.2414920  Published: March 2016  
  Abstract:Chinese character font recognition (CCFR) has received increasing attention as the intelligent applications based on optical character recognition becomes popular. However, traditional CCFR systems do not handle noisy data effectively. By analyzing in detail the basic strokes of Chinese characters, we propose that font recognition on a single Chinese character is a sequence classification problem, which can be effectively solved by recurrent neural networks. For robust CCFR, we integrate a principal component convolution layer with the 2-D long short-term memory (2DLSTM) and develop principal component 2DLSTM (PC-2DLSTM) algorithm. PC-2DLSTM considers two aspects: 1) the principal component layer convolution operation helps remove the noise and get a rational and complete font information and 2) simultaneously, 2DLSTM deals with the long-range contextual processing along scan directions that can contribute to capture the contrast between character trajectory and background. Experiments using the frequently used CCFR dataset suggest the effectiveness of PC-2DLSTM compared with other state-of-the-art font recognition methods. © 2015 IEEE.
  Accession Number: 20151400716652
• Record 339 of
  
  Title:Hardware epoch superposition of X-ray pulsar-based navigation
  
  Author(s):Wu, Yaping(1,2); Zhao, Jianjun(1); Wu, Guangmin(1); Gao, Xiafang(1,2); Tang, Haifeng(1,2)
  Source: Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica  Volume: 37  Issue: 2  DOI: 10.7527/S1000-6893.2015.0164  Published: February 25, 2016  
  Abstract:Based on the X-rays pulsar-based source simulation produced by the ground experimental system, using the method of hardware epoch superposition, the pulse profile is obtained fast and stable. The algorithm of epoch superposition and data integration implemented by the field programmable gate arrays (FPGA) has been studied that is firstly achieved by using MATLAB then converted to hardware description language (HDL) by MATLAB HDL Coder. Secondly, the stream file of Bit can be obtained, configuring the hardware by the compiler. Finally, the hardware module can be practicable in the FPGA. The arrived time data of photons obtained by MATLAB algorithm has some errors with the data obtained after the treatment of the hardware modules; the maximum error is two photon numbers in the single time window, and the average error value accounts for 0.084 % of the average statistic value; the different data accounts for 9.481% of the total number of data in the two sets of statistical pulse profile data. Such errors do not affect the navigation of the subsequent navigation module. The hardware implementation and data integration epoch superposition modules get high processing speed, compact device and low power consumption, which provides viable data processing hardware technical support for spacecraft navigation using X-ray pulsars. © 2016, Press of Chinese Journal of Aeronautics. All right reserved.
  Accession Number: 20161302163786
• Record 340 of
  
  Title:Compression solid super-continuum to 7.1fs/0.68 mJ for driving high harmonic generation
  
  Author(s):Liu, Yangyang(1); He, Peng(2); Zhao, Kun(1); Teng, Hao(1); He, Xinkui(1); Huang, Pei(1,3); Huang, Hangdong(2); Zhong, Shiyang(1); Jiang, Yujiao(2); Hou, Xun(3); Wei, Zhiyi(1)
  Source: Optics InfoBase Conference Papers  Volume:   Issue:   DOI: 10.1364/euvxray.2016.et5a.6  Published: March 14, 2016  
  Abstract:We generated white-continuum covered 450-1000nm with 85% efficiency by injected 25fs Ti:Sapphire laser at 1kHz repetition rate into fused silica pieces. With the 7.1 fs compressed pulses as driver, strong high harmonic generation was observed. © OSA 2016. © OSA 2016.
  Accession Number: 20171403526205
• Record 341 of
  
  Title:The impact of fabrication errors of double-layer BOE on diffraction efficiency
  
  Author(s):Ma, Zebin(1,2); Kang, Fuzeng(1); Wang, Hao(1,2)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 9685  Issue:   DOI: 10.1117/12.2242497  Published: 2016  
  Abstract:With the development of optical technology, optical instruments become smaller and more integrated. Because of the high diffraction efficiency and light weight, binary optical elements become more and more popular. Binary optical elements can only blaze at one wavelength, it has high diffraction efficiency at design wavelength. But the diffraction efficiency of binary optical elements will decrease quickly with the change of wavelength. And this situation will have a big impact on image quality. Since double-layer BOE can blaze at two wavelengths, it has high diffraction efficiency at wide spectral bandwidth. There are kinds of fabrication errors. Based on scalar diffraction theory, this paper analyzes the diffraction efficiency of double-layer BOE with fabrication errors and simulates it in MATLAB. Simulation shows the diffraction efficiency decreases quickly if the depth errors of two layers are opposite, and this situation should be avoided. As for periodic errors, tilt errors and angular errors, these fabrication errors have different impact of double-layer BOE on diffraction efficiency. © 2016 SPIE.
  Accession Number: 20164903095211
• Record 342 of
  
  Title:A method of removing reflected highlight on images based on polarimetric imaging
  
  Author(s):Yang, Fanchao(1,2); Tang, Xingjia(1); Hu, Bingliang(1); Wei, Ruyi(1); Kong, Liang(1); Li, Yong(1)
  Source: Journal of Sensors  Volume: 2016  Issue:   DOI: 10.1155/2016/9537320  Published: 2016  
  Abstract:A method of removing reflected highlight is proposed on polarimetric imaging. Polarization images (0°, 45°, 90°, and 135°) and the reflection angle are required in this reflected light removal algorithm. This method is based on the physical model of reflection and refraction, and no additional image processing algorithm is necessary in this algorithm. Compared to traditional polarization method with single polarizer, restricted observation angle of Brewster is not demanded and multiple reflection areas of different polarization orientations can be removed simultaneously. Experimental results, respectively, demonstrate the features of this reflected light removal algorithm, and it can be considered very suitable in polarization remote sensing. © 2016 Fanchao Yang et al.
  Accession Number: 20162402491389
• Record 343 of
  
  Title:Information encryption technology based on digital watermarkingand iteration algorithm
  
  Author(s):Xie, Qingkun(1,2); Jiang, Yanru(1,2); Zhang, Wenfei(1,2); Wang, Jing(1,2); Qu, Enshi(1)
  Source: Guangxue Xuebao/Acta Optica Sinica  Volume: 36  Issue: 6  DOI: 10.3788/AOS201636.0607001  Published: June 10, 2016  
  Abstract:The digital watermarking technology is a new information encryption technology. It has a good capacity in camouflage. However, it is limited by the phase detection errors, and the traditional retrieval algorithms are unpractical by means of calculating phase first and then deducing the original images in the process of restoring signal. The iteration algorithm can efficiently reconstruct these weak signals by applying some constrains in frequency domain and spatial domain. A new technology of information encryption and reconstruction is proposed combining with the theory of digital watermarking and iteration algorithm. This technology can overcome the limitation of phase detection errors. Furthermore, it can effectively hide and recover the embedded information, and the information can hardly be deciphered, which depends on the accuracy of phase information. Theoretical analysis and simulation results demonstrate that mean square error of the proposed algorithm can accomplish convergence by only several iterations within few seconds, which shows high robustness. It has a good performance in camouflage and fast-convergence, and could be widely applied in personal identity camouflage and information identity. © 2016, Chinese Lasers Press. All right reserved.
  Accession Number: 20162502529783
• Record 344 of
  
  Title:Design of a mid-wavelength infrared dual field of view zoom system
  
  Author(s):Duan, Jing(1); Li, Gang(1,2); Jiang, Kai(1); Liu, Kai(1); Yan, Peipei(1,2); Shan, Qiusha(1)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 10154  Issue:   DOI: 10.1117/12.2246694  Published: 2016  
  Abstract:In order to effectively improve the target detection and recognition ability of IR imagers, based on a 320×256 cooled staring focal plane array(FPA) detector, pixel size 30μm×30μm, a mid-wavelength infrared dual field of view zoom system was designed. In this paper, the working wavelength is 3μmï1/2ž5μm, the temperature range is-40°C∼+50°C, this system can realize 200mm and 400mm dual focal length, the F-number is 2, the full field of view of short focal length is 3.44° and long focal length is 1.72° respectively, satisfy 100% cold shield efficiency. A re-imaging refractive system was adopted in this designed optical system consists of main optics and projection components. First of all, the structural selection and the initial parameter calculation were introduced in detail. Secondly, on the basis of variety of the distance and temperature, a focusing lens was presented in this system to adjust to produce a clear image. Last but not the least, to improve image quality and environment adaptability, the analysis of temperature change and narcissus effect were described particularly. The design results prove that at the spatial frequency of 17 lp/mm, the MTF of the optical system is greater than 0.5(the axis MTF of the optical is greater than 0.6), the system can offer a high resolution and excellent images in whole range of the focal length, and it has the advantages of good adaptability, compact structure, high optical transmission and small size. © 2016 SPIE.
  Accession Number: 20170503310088
• Record 345 of
  
  Title:Annular-force-based variable curvature mirror combined with multi-point actuation array to improve the surface figure accuracy: A prototype design
  
  Author(s):Zhao, Hui(1); Xie, Xiaopeng(2); Ren, Guorui(1); Du, Yunfei(1); Liu, Meiying(1); Wei, Jingxuan(3)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 9683  Issue:   DOI: 10.1117/12.2242256  Published: 2016  
  Abstract:In recent years, a novel optical zooming technique has been paid much attention. With the help of optical leveraging effect, it is possible to alter the system focal length dramatically without moving elements involved in by only changing the curvature radius of VCM (variable curvature mirror) slightly. With no doubt, VCM is the key to realize non-moving element optical zooming and it has to provide large enough saggitus variation while still maintaining the high surface figure accuracy to ensure high quality imaging. In our previously published paper, an annular force based VCM has been designed, fabricated and tested. Experiments demonstrate that with the aperture of 100mm and thickness of 2mm, the VCM could generate a large saggitus variation exceeding 30 (=632.8nm). However, the optical quality degrades very fast and this makes such a VCM unsuitable for optical imaging in visible band. Therefore in this manuscript, a multipoint actuation array, which is composed of totally 49 piezoelectric actuators, is embedded into the annular structure to aim to correct the surface figure distortion caused by large saggitus variation. The new structure model has been designed and numerical simulation indicates that the surface figure distortion could be well corrected as long as the degraded surface figure accuracy is better than 1.8 (=632.8nm) (RMS). Based on this, a new prototype VCM is being fabricated and intermediate results are reported here. © 2016 SPIE.
  Accession Number: 20164903096456
• Record 346 of
  
  Title:Research on lightweight passive deployment mechanism for the secondary mirror in the deployable space telescope
  
  Author(s):Zhong, Peifeng(1,2); Li, Chuang(1); Jing, Nan(1,2); Chong, Yaqin(1,2); Ren, Guorui(1)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 9685  Issue:   DOI: 10.1117/12.2243221  Published: 2016  
  Abstract:In this paper, a new type of lightweight passive deployment mechanism based on the tape spring and the shape memory alloy is presented for the secondary mirror of a deployable space telescope. In this passive deployment mechanism for the secondary mirror, the high elastic potential energy of the folded tape springs is used as driving force when the support structure is extended, and the high stiffness characteristics of the circular arc cross section of the tape spring can be used to achieve structure self-locking after deployment. Then a deployable space telescope combined with lightweight passive deployable mechanism for the secondary mirror is designed for applying to nanosatellite imaging. Furthermore, a lock-release device is designed to achieve the function of locking the folded structure and releasing on orbit by taking advantage of the phase transformation characteristics of shape memory alloy with temperature changing. Finally, the correction method for the deployment error of secondary mirror is discussed. The temperature of the tape springs is controlled respectively to make a required length change. This can achieve the purpose of adjusting the position of the secondary mirror and improve the deployment accuracy. © 2016 SPIE.
  Accession Number: 20164903095242
• Record 347 of
  
  Title:Design of and experiment on the polarization dehazing imaging system
  
  Author(s):Xia, Pu(1,2); Liu, Xuebin(1); Yan, Peng(1)
  Source: Xi'an Dianzi Keji Daxue Xuebao/Journal of Xidian University  Volume: 43  Issue: 2  DOI: 10.3969/j.issn.1001-2400.2016.02.017  Published: April 1, 2016  
  Abstract:In view of the requirement of image quality, integration level and real-time application of the imaging systems under fog weather, this paper reports a polarization imaging system with a dehazing ability. The differential signal is converted by FPGA, and a highly integrated CMOS imaging circuit is built based on the internal PLL of the image sensor and the CamLink protocol. The obtained image is inversed by stokes equations, and the real-time dehazing algorithm is realized by the built-in DSP module. The total size of the polarization imaging system is 117 mm×117 mm×126 mm, and the weight of the system is 1.2 kg. An imaging experiment was made under fog weather, and the dehazing ability of the imaging system is proved by the contrast of the original image and the dehazed image's histogram and RGB distribution. Experimental results show that the imaging system can stably obtain a color dehazed image at 2 048×2 048 @ 180 Hz. © 2016, Science Press. All right reserved.
  Accession Number: 20162002388438
• Record 348 of
  
  Title:Experiment research and analysis of spectral prediction on soil leaking oil content
  
  Author(s):Yu, Lu(1,2,3); Liu, Xue-Bin(1); Liu, Gui-Zhong(2); Feng, Yu-Tao(1); Wang, Shuang(1); Yu, Tao(1)
  Source: Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis  Volume: 36  Issue: 4  DOI: 10.3964/j.issn.1000-0593(2016)04-1116-05  Published: April 1, 2016  
  Abstract:The spectral analysis method was applied experimentally to extract the spectral indices, measure and analyze the spectral characteristics and their difference of the mixture which are composed in soil in Central Shaanxi Plain and the diesel and motor oil respectively, aiming to provide solutions to practical difficulties in detecting, analyzing the spectral characteristics and difference between the soil leaking with equal content diesel and motor oil and predicting the leaking content of diesel in the soil. The spectral response curves of the soil leaking with different oil respectively and the soil leaking with diesel with different content were collected. Then the spectral prediction model for the leaking content of diesel in the soil was built based on the reflectance characteristics. The coefficient of the detection (R2) was introduced to evaluate the stability of the built model, and the parameter root mean squared error (RMSE) was introduced to estimate the precision and the predictability of the model built in this work. It is demonstrated that: (1) The reflectance of soil leaking with diesel is less than that of the equal content motor oil. And there is a double absorption trough of the reflectance curve of both soil leaking with diesel and motor oil at 1740 and 2328 nm. The spectral absorption indices and absorption depth of the soil leaking with diesel keep less than the equal content motor oil. (2) The built spectral prediction model for the leaking content of diesel in the soil demonstrates good stability with the coefficient of determination at R2=0.854, and performs favorable predictability (Root-Mean-Square Error, RMSE=0.016), which can benefit the effective prediction and quick estimation methods of the leaking content of diesel in the soil, enrich and progress the experimental method and theoretical research work of spectral prediction on soil leaking oil content and promote the application of remote sensing in safety production and environmental protection. © 2016, Peking University Press. All right reserved.
  Accession Number: 20161902371767