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2017

Record 217 of

Title:Particle model for optical noisy image recovery via stochastic resonance

Author(s):Zhang, Yongbin(1,3); Liu, Hongjun(1,2); Huang, Nan(1); Wang, Zhaolu(1); Han, Jing(1,3)
Source: Applied Physics Express Volume: 10 Issue: 10 DOI: 10.7567/APEX.10.102501 Published: October 2017
Abstract:We propose a particle model for investigating the optical noisy image recovery via stochastic resonance. The light propagating in nonlinear media is regarded as moving particles, which are used for analyzing the nonlinear coupling of signal and noise. Owing to nonlinearity, a signal seeds a potential to reinforce itself at the expense of noise. The applied electric field, noise intensity, and correlation length are important parameters that influence the recovery effects. The noise-hidden image with the signal-to-noise intensity ratio of 1 : 30 is successfully restored and an optimal cross-correlation gain of 6.1 is theoretically obtained. ? 2017 The Japan Society of Applied Physics.
Accession Number: 20174304300122
Record 218 of

Title:Super-resolution reconstruction theory in structured illumination microscopy

Author(s):Zhou, Xing(1); Dan, Dan(1); Qian, Jia(1); Yao, Baoli(1); Lei, Ming(1)
Source: Guangxue Xuebao/Acta Optica Sinica Volume: 37 Issue: 3 DOI: 10.3788/AOS201737.0318001 Published: March 10, 2017
Abstract:In recent years, the resolution of far field optical imaging has broken the limit of diffraction limit with the appearance of new fluorescent probes and the improvement of imaging methods. The fluorescence microscopy based on structured illumination has become one of the main superresolution imaging techniques owing to its advantages such as fast imaging speed and light toxicity. The most critical technologies in structured illumination microscopy are concentrated on rapid control of the high-quality illumination pattern and the image reconstruction method. An unsuitable method will generate the artifacts in the reconstruction super-resolution image and that may confuse the scientific evaluation of biological morphology. Several typical structured illumination microscopic super resolution reconstruction algorithms are compared. It is proven that the image transform of the structured illumination microscopic super resolution reconstruction algorithm based on image recombination transform can effectively solve the low structure light modulation under the super-resolution image reconstruction problem, and reduce the excitation power of the structured illumination microscopy. ? 2017, Chinese Lasers Press. All right reserved.
Accession Number: 20171603576223
Record 219 of

Title:Denoising algorithm of pulsar signal based on EMD with kurtosis test window

Author(s):Wang, Lu(1); Li, Jianxun(1,2); He, Tingting(1)
Source: Xi Tong Gong Cheng Yu Dian Zi Ji Shu/Systems Engineering and Electronics Volume: 39 Issue: 6 DOI: 10.3969/j.issn.1001-506X.2017.06.04 Published: June 1, 2017
Abstract:For the problem that pulsar signal and noise are aliasing on the intrinsic mode functions (IMF) during the empirical mode decomposition (EMD), a denoising method based on EMD with kurtosis test window is proposed. Firstly, the starting point for IMF refactoring is calculated by auto-correlation and cross-correlation. On that basis, the left and the right endpoints of the pulse part of signal from the former two IMFs of the starting point for refactoring are acquired by the local kurtosis test. Finally, the adaptive threshold method is used to remove noise and improve signal quality. The experimental results show that, compared with the other five methods, the proposed method has higher denoising performance, which can effectively eliminate the noises and retain the details in pulsar signal. ? 2017, Editorial Office of Systems Engineering and Electronics. All right reserved.
Accession Number: 20173404075756
Record 220 of

Title:Optimization of the doughnut-shaped depletion spot in stimulated emission depletion microscopy

Author(s):Cai, Yanan(1); Wang, Zhaojun(1); Liang, Yansheng(1); Yan, Shaohui(1); Dan, Dan(1); Yao, Baoli(1); Lei, Ming(1)
Source: Guangxue Xuebao/Acta Optica Sinica Volume: 37 Issue: 3 DOI: 10.3788/AOS201737.0318009 Published: March 10, 2017
Abstract:Stimulated emission depletion microscopy (STED) is a powerful far-field technique for super-resolution optical imaging with a few tens even a few of nanometer spatial resolution, thus it is extensively used in investigation of cell biology and so on. The spatial resolution of STED highly depends on the intensity distribution of the doughnut-shaped depletion spot, near the objective focus. The polarization state of field has influence on focal intensity focused with high numerical aperture objective. The off-axis aberrations of microscopic system bring serious damage to the central symmetry of doughnut-shaped depletion spot. The influences of different polarization states of incidence vortex beam and aberrations of coma and astigmatism is of the optical system on the intensity profiles of doughnut-shaped depletion spot simulated by using the vectorial diffraction theory. In the experiment, the deformed depletion spot is optimized by utilizing a pure phase spatial light modulator to correct the aberrations of the optical system. A fluorescent nanoparticle is used as a probe to scan the focal region to obtain a high spatial resolution of intensity distribution. The measured results are in good agreement with those predicted by the vectorial diffraction theory. ? 2017, Chinese Lasers Press. All right reserved.
Accession Number: 20171603576231
Record 221 of

Title:Stochastic resonance based on modulation instability in spatiotemporal chaos

Author(s):Han, Jing(1,2); Liu, Hongjun(1,3); Huang, Nan(1); Wang, Zhaolu(1)
Source: Optics Express Volume: 25 Issue: 7 DOI: 10.1364/OE.25.008306 Published: April 3, 2017
Abstract:A novel dynamic of stochastic resonance in spatiotemporal chaos is presented, which is based on modulation instability of perturbed partially coherent wave. The noise immunity of chaos can be reinforced through this effect and used to restore the coherent signal information buried in chaotic perturbation. A theoretical model with fluctuations term is derived from the complex Ginzburg-Landau equation via Wigner transform. It shows that through weakening the nonlinear threshold and triggering energy redistribution, the coherent component dominates the instability damped by incoherent component. The spatiotemporal output showing the properties of stochastic resonance may provide a potential application of signal encryption and restoration. ? 2017 Optical Society of America.
Accession Number: 20171403544904
Record 222 of

Title:Template deformation-based 3-D reconstruction of full human body scans from low-cost depth cameras

Author(s):Liu, Zhenbao(1); Huang, Jinxin(1); Bu, Shuhui(1); Han, Junwei(1); Tang, Xiaojun(1); Li, Xuelong(2)
Source: IEEE Transactions on Cybernetics Volume: 47 Issue: 3 DOI: 10.1109/TCYB.2016.2524406 Published: March 2017
Abstract:Full human body shape scans provide valuable data for a variety of applications including anthropometric surveying, clothing design, human-factors engineering, health, and entertainment. However, the high price, large volume, and difficulty of operating professional 3-D scanners preclude their use in home entertainment. Recently, portable low-cost red green blue-depth cameras such as the Kinect have become popular for computer vision tasks. However, the infrared mechanism of this type of camera leads to noisy and incomplete depth images. We construct a stereo full-body scanning environment composed of multiple depth cameras and propose a novel registration algorithm. Our algorithm determines a segment constrained correspondence for two neighboring views, integrating them using rigid transformation. Furthermore, it aligns all of the views based on uniform error distribution. The generated 3-D mesh model is typically sparse, noisy, and even with holes, which makes it lose surface details. To address this, we introduce a geometric and topological fitting prior in the form of a professionally designed high-resolution template model. We formulate a template deformation optimization problem to fit the high-resolution model to the low-quality scan. Its solution overcomes the obstacles posed by different poses, varying body details, and surface noise. The entire process is free of body and template markers, fully automatic, and achieves satisfactory reconstruction results. ? 2013 IEEE.
Accession Number: 20161002045074
Record 223 of

Title:A new kind of vertically aligned field emission transistor with a cylindrical vacuum channel

Author(s):Shen, Zhihua(1); Wang, Xiao(1); Wu, Shengli(1); Tian, Jinshou(2)
Source: Vacuum Volume: 137 Issue: DOI: 10.1016/j.vacuum.2017.01.002 Published: March 1, 2017
Abstract:This study investigated a vertically aligned field emission transistor with a cylindrical vacuum channel. The channel length of this proposed transistor can be precisely controlled and easily fabricated to be comparable to the mean free path of electrons in air so that the device can operate in the air without performance degradation. In the study, this vacuum transistor showed a low threshold voltage (1.2?V, 2.2?V, and 3.3?V) with a gate dielectric thickness of 10?nm, 15?nm, and 20?nm and a subthreshold slope of 1.1?V/dec. It was found that the vacuum channel radius should be no less than 20?nm, otherwise, severe performance degradation will appear due to the effect of the gate shield (leading to reduction of the anode current) and electron collision events with the dielectric layer (presenting reliability issues). This kind of vacuum transistor may have wide applications in extreme conditions such as high temperature and intense irradiation. ? 2017
Accession Number: 20170203239137
Record 224 of

Title:Numerical analysis of thermally tunable liquid-crystal-filled terahertz fiber

Author(s):Wang, Doudou(1,2); Ma, Hongwei(2); Wang, Lili(3); Li, Baihong(1); Yang, Jing(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10256 Issue: DOI: 10.1117/12.2257112 Published: 2017
Abstract:A liquid-crystal-filled polymer photonic crystal fiber is designed and numerically analysised for terahertz wave guiding. Bandgap-guiding terahertz fiber is obtained by infiltrating the cladding air holes of index guiding Topas photonic crystal fiber with liquid crystal 5CB. Structural parameter dependence and thermal tunability of the photonic bandgaps, mode properties and confinement losses of the designed fiber are investigated by using the finite element method. The bandgaps are formed based on antiresonances of the individual liquid crystal inclusions, so the positions of bandgaps depend strongly on the cladding hole diameter and weakly on the lattice constant. Bandgaps and the positions of the confinement loss minimum or peaks of the transmission spectra shift toward lower frequency as temperature increased from 25 °C to 34 °C due to the positive dno/dT of 5CB. Average thermal tuning sensitivity of -30 GHz/°C is achieved for the designed fiber. At the central frequency of the transmission band, high power transmission coefficient and thus low splicing loss between the aligned liquid-crystal-filled polymer photonic crystal fiber and the unfilled section is obtained. Our results provide theoretical references for applications of liquid-crystal photonic crystal fiber in sensing and tunable fiber-optic devices in terahertz frequencies. ? 2017 SPIE.
Accession Number: 20171703607643
Record 225 of

Title:Nonresonant background suppression in wide-field coherent anti-Stokes Raman scattering microscopy with transport of intensity equation based phase imaging

Author(s):Zheng, Juan-Juan(1); Yao, Bao-Li(2); Shao, Xiao-Peng(1)
Source: Wuli Xuebao/Acta Physica Sinica Volume: 66 Issue: 11 DOI: 10.7498/aps.66.114206 Published: June 5, 2017
Abstract:Coherent anti-Stokes Raman scattering (CARS) microscopy is a valuable tool for label-free imaging of biological samples, since it enables providing contrast via vibrational resonances of a specific chemical bond. However, in a conventional CARS image the Raman resonant anti-Stokes radiation is often superimposed by a nonresonant contribution arising from the electronic part of the polarization. The situation becomes worse if a sample is composed of a significant amount of water, where a strong nonresonant background over the whole image is obtained. To date, various approaches including Epi, polarization sensitive, time-resolved, and CARS phase imaging have been implemented to suppress the undesirable nonresonant background in CARS microscopy. Notably, optical heterodyne based phase imaging schemes are of particular interest due to their intrinsic ability to retrieve Im(χ(3)), which is proportional to the Raman resonant signal. Nevertheless, all the reported phase imaging methods that require an independent reference wave lead to an increase in the setup complexity, thus making the measurement sensitive to external perturbations. In order to simplify the setup, single-beam scheme has also been utilized for vibrational CARS imaging by using wave-front sensors to acquire the phase of the complex anti-Stokes amplitude. However, this method demands highly accurate wave-front sensors. In this paper we present a reference-less CARS phase imaging technique to suppress nonresonant CARS background based on transport of intensity equation (TIE). Resonant CARS radiation ECARSR can be obtained when the frequency difference between the pump and Stokes beams is tuned to match a molecular vibration frequency (Raman resonant mode). In contrast, the nonresonant background ECARSNR can be obtained when the frequency difference between the pump and Stokes beams does not match a molecular vibration frequency (Raman resonant mode). Considering the fact that there is a phase shift of π/2 between the resonant and non-resonant CARS field, the phase imaging of both resonant and nonresonant CARS field can provide a background-free image. In implementation, three intensity images of the CARS field under resonant mode are recorded at three neighboring planes by moving the CCD camera along the axial direction. In the meantime, three images of the CARS field under non-resonant mode are also recorded. Considering the fact that the TIE links the intensity distributions in three neighboring planes (through which a beam transverses) with the phase distribution of the field, the phase images of the CARS field under both resonant and nonresonant modes are reconstructed from the recorded intensity images. The phase difference φχ between the resonant CARS field and the non-resonant CARS field is calculated. Eventually, the CARS background is efficiently suppressed by using the relation IbfCARS ∝ ICARSR · sin2 φχ. Compared with conventional CARS background suppression techniques, the proposed method is robust against environmental disturbance, since it does not require an additional reference beam. Furthermore, the proposed method is easy to incorporate in a conventional CARS configuration. Therefore, the proposed method has the potential to become a versatile technique to image deep tissue with low background signal. ? 2017 Chinese Physical Society.
Accession Number: 20173103998760
Record 226 of

Title:Nested grazing incidence optics for x ray detection

Author(s):Li, Lin-Sen(1,2,3); Qiang, Peng-Fei(1,3); Sheng, Li-Zhi(3); Liu, Yong-An(1,3); Liu, Zhe(3); Liu, Duo(1,3); Zhao, Bao-Sheng(3); Zhang, Chun-Min(2)
Source: Chinese Physics B Volume: 26 Issue: 10 DOI: 10.1088/1674-1056/26/10/100703 Published: October 2017
Abstract:Grazing incidence optics (GIO) is the most important compound in an x-ray detection system; it is used to concentrate the x-ray photons from outer space. A nested planar GIO for x-ray concentration is designed and developed by authors in this paper; planar segments are used as the reflection mirror instead of curved segments because of the simple process and low cost. After the complex assembling process with a special metal supporter, a final circle light spot of φ12 mm was obtained in the visible light testing experiment of GIO; the effective area of 1710.51 mm2@1 keV and 530 mm2@8 keV is obtained in the x-ray testing experiment with the GIO-SDD combination, which is supposed to be a concentrating detector in xray detection systems. ? 2017 Chinese Physical Society and IOP Publishing Ltd.
Accession Number: 20174204273360
Record 227 of

Title:Efficiency analysis of 808 nm laser diode array under different operating temperatures

Author(s):Song, Yun-Fei(1,2); Wang, Zhen-Fu(1); Li, Te(1); Yang, Guo-Wen(1,3)
Source: Wuli Xuebao/Acta Physica Sinica Volume: 66 Issue: 10 DOI: 10.7498/aps.66.104202 Published: May 20, 2017
Abstract:The 808 nm high-efficiency laser diodes have many advantages, such as high output power, high reliabilities, compact sizes, which are widely used in many areas, such as industry, communication, science, medicine and biology. In order to improve the power conversion efficiencies of 808 nm laser diodes, the following requirements must be considered, such as loss of joule heating, loss by the carrier leakage, spontaneous radiation loss below the threshold current, loss by interface voltage defect, internal losses including free-carrier absorption loss and scattering loss. These losses above are closely related to the operating temperature of laser diode. In this paper, power conversion efficiency analysis is demonstrated from the aspects of the output power, threshold current, slope efficiency, voltage, and series resistance at different temperatures.. This is the first time that the detailed study has been carried out under various temperatures (up to the lowest temperature of -40℃). And the detailed study above can be of benefit to designing the wafer epitaxial structure. High-power 808 nm laser diode arrays are mounted on conduction cooled heatsinks. And the laser chips have 47 emitters with 50% in fill factor, 100 μm stripe in width and 1.5 mm in cavity length. The asymmetric broad waveguide epitaxial structure with lower absorption loss in p-type waveguide and cladding layer is designed in order to reduce the internal losses. The device performances are measured under operating temperatures ranging from -40℃ to 25℃ including the output power, threshold current, slope efficiency, series resistance, voltage, etc. Then the power conversion efficiency of 808 nm laser diode arrays are demonstrated from the output characteristics at different operating temperatures. With temperature decreasing, the series resistance gradually increases. The loss of joule heating ratio rises from 7.8% to 10.3%. In that case, the high series resistance is the major factor to prevent the efficiency from further improving at a low temperature of -40℃. As temperature decreases from 25℃ to -40℃, the carrier leakage ratio is reduced from 16.6% to 3.1%, the carrier leakage is the dominant factor for increasing efficiency, which means that it is necessary to optimize the epitaxial structure in order to reduce the carrier leakage at the room temperature. Comparing the two different work temperatures from -30℃ to -40℃, the carrier leakage ratio only changes 0.1%, which implies that the carrier leakage could be ignored under the low temperature. Meanwhile, as temperature decreases from 25℃ to -40℃, the power conversion efficiency increases from 56.7% to 66.8%. ? 2017 Chinese Physical Society.
Accession Number: 20173003988115
Record 228 of

Title:Raman Spectroscopy System for Non-invasive Blood Glucose Detection

Author(s):Zheng, Yi(1,2); Zhu, Xiang-Ping(1); Nie, Rong-Zhi(1,2,3); Gao, Fei(1); Cui, Xiao-Xia(1); She, Jiang-Bo(1); Peng, Bo(1)
Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 46 Issue: 8 DOI: 10.3788/gzxb20174608.0812005 Published: August 1, 2017
Abstract:A miniature wearable Raman spectroscopy system used to achieve noninvasive detection of human blood glucose level was developed. A thallium-doped grin lens was employed as the collection lens and a specially designed wearable fiber optic probe was employed to help the stable and convenient collection of Raman spectrum. The glucose solution, 11 rats and 10 healthy human were studied as subjects. In addition, a method of quantitative analysis of Raman spectrum was proposed which using the peak area as the main reference factor while the peak intensity as the auxiliary reference factor to calculate the target concentration. A non-linearized multivariate dominant factor-based partial least squares model was built for different samples to predict glucose level. The results show that the accuracy are 98.1%, 89.3% and 84.4% for glucose solution, rats and human subjects. The system has the advantages of more compact structure, lower cost, better testing stability and convenient for human body to wear, and is feasible and repeatable to achieve the noninvasive detection of human blood glucose accurately. ? 2017, Science Press. All right reserved.
Accession Number: 20173504083804

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