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2017
Volume: 54 Issue 4
39 Article(s)
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Atmospheric Optics and Oceanic Optics
Influence Factors on Atmospheric Aerosol Optical Property Inversion in Nanjing
Song Xiuyu, Cao Nianwen, and Yang Sipeng
The optical property of atmospheric aerosol in Nangjing is inversed, and the different factors which can influence the inversion accuracy of extinction coefficient of atmospheric aerosol are studied. The de-noising processing for signal is carried out by different methods，and the suitable de-noising method is found. ThThe optical property of atmospheric aerosol in Nangjing is inversed, and the different factors which can influence the inversion accuracy of extinction coefficient of atmospheric aerosol are studied. The de-noising processing for signal is carried out by different methods，and the suitable de-noising method is found. The reprocessing for de-noised signal is carried out with five-point triple smoothing, wavelet de-noising and eleven-point smoothing respectively, and the method which can obtain accurate inversion result is chosen. The effects of logarithmic ratio of backscatter extinction and extinction coefficient at the reference height on the inversion result of Klett method are analyzed. The inversion results when k ranges from 0.67 to 1.0 and σm is about 1×10-5 km-1 are analyzed. The influence of the lidar ratio on the inversion result of Fernald method is analyzed when the lidar ratio ranges from 20 to 70. The results of Klett method are compared with that of Fernald method. It is found that in the region with low atmospheric aerosol content, the results of the two methods are different, but the results of the two methods are almost same in the region with high aerosol content..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 40101 (2017)
Detectors
Numerical Research on Photodiode Damage by Multi-Pulsed Laser Irradiation
Zhao Hongyu, Wei Zhi, and Jin Guangyong
All of the photoelectric detectors under laser irradiation are likely to be damaged, which has a bad effect on the detector performance. In order to study the photodiode damage caused by the multi-pulsed laser irradiation, a two-dimensional axisymmetric model and a heat source model of the photodiode irradiated by the All of the photoelectric detectors under laser irradiation are likely to be damaged, which has a bad effect on the detector performance. In order to study the photodiode damage caused by the multi-pulsed laser irradiation, a two-dimensional axisymmetric model and a heat source model of the photodiode irradiated by the multi-pulsed laser are built. Temperature distribution of the photodiode irradiated by the 1064 nm millisecond multi-pulsed laser is simulated by the finite element software COMSOL Multiphysics. Results show that when the pulse number N of the multi-pulsed laser irradiation is 1, 3, 5, 10, 30, respectively, pulse energy density region required by the fusion damage threshold of the photodiode is 19.1-76.4 J/cm2. The research results are helpful for the millisecond multi-pulsed laser in laser processing and the application of laser protection..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 40401 (2017)
Fiber Optics and Optical Communications
Optical Fiber Grating Temperature and Axial Tension Sensing System Based on Swept Source
Su Hong, Wang Jian, Liu Lanlan, and Wu Chongqing
The demodulation part of a traditional fiber grating sensing system with a broadband light source is complex. In order to overcome this shortcoming, a linear swept laser is used as light source of the FBG sensor system. One of the gratings is used as reference grating, and other gratings are used as sensing gratings. TThe demodulation part of a traditional fiber grating sensing system with a broadband light source is complex. In order to overcome this shortcoming, a linear swept laser is used as light source of the FBG sensor system. One of the gratings is used as reference grating, and other gratings are used as sensing gratings. The change of the reflection center wavelength of FBG is obtained according to the change of time interval between reflection signals of the sensing grating and the reference grating. The demodulation process is very simple and straightforward. The FBG sensing system is used to accomplish experiments of temperature measurement and fiber axial tension measurement. The results verify the feasibility and the correctness of the FBG sensing system and also prove that the FBG sensing system can either individually or simultaneously measure temperature and fiber axial tension. Some methods which improve the measurement precision are presented, including keeping the temperature of reference grating stable and using the swept light source with low swept rate and the oscilloscope with high sampling rate..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 40601 (2017)
Feasibility of Gold-Plated Fiber Bragg Grating Sensors Used in Lithium Ion Battery in-Situ Detection
Liu Yanchao, Fang Jin, Xu Chong, Wei Bin, Guan Yibiao, Fan Maosong, Yan Xufeng, and Gao Chao
A method of lithium ion battery in-situ detection is proposed. In the proposed method, gold-plated fiber Bragg grating(FBG)sensors are embedded in the making process of lithium ion batteries to acquire the initial physical quantities of lithium ion batteries. The position and the method for the FBG sensor embedded in lA method of lithium ion battery in-situ detection is proposed. In the proposed method, gold-plated fiber Bragg grating(FBG)sensors are embedded in the making process of lithium ion batteries to acquire the initial physical quantities of lithium ion batteries. The position and the method for the FBG sensor embedded in lithium ion battery are studied, and the performance of battery embedded with gold-plated FBG sensor is analyzed. The charge-discharge experiments for lithium ion batteries are carried out, and the battery samples used in experiments are unpacked. The experimental results show that gold-plated FBG sensors can be used in the temperature collection in general environment. The gold-plated layer structure in the lithium ion battery is corroded, which results in wavelength drift. The bare FBG′s structure is not destroyed due to the presence of the gold-plated layer, so the internal temperature of battery can be collected after re-calibrating FBG sensor. This research provides a reference for the FBG sensor used in in-situ detection for lithium ion batteries..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 40602 (2017)
Influence of Optical Dome on Airborne Laser Communication Beam Far-Field Divergence Angle
Wang Chao, Jiang Lun, Tong Shoufeng, Li Yingchao, and Liu Zhuang
When the centers of inner and outer surfaces of the concentric spherical surface dome and the gimbal joint of the airborne laser communication transmitting antenna are not coincidence, the influence of the asymmetry optical dome on communication beam far-field divergence angle is analyzed. The results show that, at a mWhen the centers of inner and outer surfaces of the concentric spherical surface dome and the gimbal joint of the airborne laser communication transmitting antenna are not coincidence, the influence of the asymmetry optical dome on communication beam far-field divergence angle is analyzed. The results show that, at a maximal communication beam far-field divergence angle of 54°, a K9 spherical dome with the external diameter of 200 mm and the thickness of 5 mm makes the communication beam far-field divergence angle expand to 5.27-6.46 mrad from 126 μrad. The communication beam far-field divergence angle variation purely introduced by the dome surface manufacturing precision is very tiny, and can be ignored compared with the variation introduced by the dome optical power. A lens with spherical surfaces is used to compensate the communication beam far-field divergence angle change, and the communication beam far-field divergence angle of the whole transmitting angle range is smaller than 600 μrad..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 40604 (2017)
Temperature Characteristics of Micro-Nanofiber Bragg Grating Surrounded with Liquids
Liu Yinggang, and Zhang Wei
In order to investigate the temperature dependence of micro-nanofiber Bragg grating (MNFBG) in application, we simulate the relationship between reflection wavelength and temperature of MNFBG which is surrounded with liquids with different refractive indexes, and MNFBGs surrounded with replaceable encapsulating liquidsIn order to investigate the temperature dependence of micro-nanofiber Bragg grating (MNFBG) in application, we simulate the relationship between reflection wavelength and temperature of MNFBG which is surrounded with liquids with different refractive indexes, and MNFBGs surrounded with replaceable encapsulating liquids are fabricated and used in experiments. In experiments, the variations in reflection spectral and its center wavelength with temperature of encapsulating liquids can be obtained when we encapsulate the MNFBG with distilled water and matching liquids with different reflective indexes. Research results show that the shape and the moving direction of reflection spectra can be effected by the encapsulating liquids with different properties in the same temperature changing process, which is different from the ordinary fiber Bragg grating (FBG). The reflection spectral shape of the ordinary FBG almost does not change when temperature is increasing, but its center wavelength increases with the temperature increasing linearly. The larger the refractive index and the thermo-optic coefficient of the encapsulating liquids are, the more nonlinearity the spectral wavelength shifting with temperature changing is. When the MNFBG is surrounded with the liquid with the refractive index of 1.456 and the thermo-optic coefficient of 4×10-4 ℃-1, the temperature sensitivity of the reflection wavelength can reach up to -50.3 pm/℃. These spectral characteristics of MNFBG are connected with the surround liquid, the temperature and the size of FBG. Through effectively controlling these correlative factors, more functional applications of FBG will be realized in different fields..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 40605 (2017)
Holography
Two-Step Phase-Shifting Based Incoherent Digital Holographic Microscopy
Li Yingying, Qin Wan, Gao Zhi, and Peng Xiang
Two-step phase-shifting based on wavelet transform to suppress bias term is reported, and the initial image is used to eliminate background noise. Specific forms of reconstructing hologram and suppressing bias term are given. An incoherent digital holographic microscopy system based on spatial light modulator is built Two-step phase-shifting based on wavelet transform to suppress bias term is reported, and the initial image is used to eliminate background noise. Specific forms of reconstructing hologram and suppressing bias term are given. An incoherent digital holographic microscopy system based on spatial light modulator is built and the holograms and reconstruction results of both three-step phase-shifting and two-step phase-shifting are given. Reconstruction results of the two methods are compared. Experiment captures two holograms of the microscopic fluorescent beads which realize digital reconstruction in different planes using the method presented in this paper. Two-step phase-shifting significantly enhances imaging speed compared to three-step phase-shifting, and provides the possibility to image 3D living cells dynamically. The result shows that wavelet transform can suppress bias term more effectively. We improve the quality of reconstructed image by two-step phase-shifting without increasing the phase-shifting step..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 40901 (2017)
Image Processing
Blind Road Segmentation Based on Saliency Detection and Improved Projective Dictionary Pair
Wang Min, Xiao Lei, and Yang Fang
The current blind road segmentation algorithms are used to segment by extracting the color or texture feature, and by using the clustering method, which are vulnerable to blind road types and the external environment. To solve this problem, a learning approach is introduced, and a blind road segmentation method is propThe current blind road segmentation algorithms are used to segment by extracting the color or texture feature, and by using the clustering method, which are vulnerable to blind road types and the external environment. To solve this problem, a learning approach is introduced, and a blind road segmentation method is proposed based on saliency detection and improved projection dictionary from the consideration of the global feature of blind road. Firstly, the saliency detection algorithms are used to roughly locate the blind road region. Then the image piece is used as the processing unit, and the dictionary is learned through the robust projective dictionary pair learning proposed. And the coarse image after location is divided into blocks to sparsely reconstruct on the dictionary. Finally, the rough-positioned images are reconstructed on the dictionary, and classified according to the reconstruction error to achieve the purpose of segmentation. Experimental results show that the proposed algorithm performs better than the existing algorithms in terms of accuracy and universality in blind road segmentation..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 41001 (2017)
Nighttime Image Defogging Based on the Theory of Retinex and Dark Channel Prior
Yang Aiping, and Bai Huanghuang
Nighttime image defogging is critical for various applications, such as nighttime video surveillance, and target identification. The existing defogging algorithms for nighttime image have many shortcomings, such as high image distortion, fuzzy detail and poor robustness. In order to solve these problems, a new nighttimNighttime image defogging is critical for various applications, such as nighttime video surveillance, and target identification. The existing defogging algorithms for nighttime image have many shortcomings, such as high image distortion, fuzzy detail and poor robustness. In order to solve these problems, a new nighttime image defogging algorithm based on the theory of Retinex and dark channel prior is proposed combining with the characteristics of atmospheric scattering model and nighttime image of fog. Firstly, the incidence image affected by haze and the reflection image affected by haze are obtained based on the theory of Retinex. Then, the clear reflection image is obtained by the dark channel prior. After that, the position of the source and the depth of field are obtained according to the nighttime image of fog and the reflection image affected by haze. The sum of the distances between the spot and the source is obtained by using the camera imaging mechanism, and then the fog-free incident light image is obtained. Finally, the theory of Retinex is used to restore the nighttime clear image. Experimental results show that the proposed algorithm not only defogs completely and enhances the image contrast, but also reduces the color distortion greatly..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 41002 (2017)
Instrumentation, Measurement and Metrology
Design of Autostereoscopic 3D Display with no Crosstalk and Full Resolution
Chen Fangping, Zhang Xiaoting, Wang Xiaoyan, Liu Chujia, Qi Yu, and Zhuang Qiren
The applicability of lenticular-lens-based autostereoscopic 3D display is limited due to its crosstalk and degradation of resolution. Autostereoscopic display with no crosstalk and full resolution is realized by designing a butterfly-shaped liquid crystal display shutter in a multi-directional backlight unit. And the cThe applicability of lenticular-lens-based autostereoscopic 3D display is limited due to its crosstalk and degradation of resolution. Autostereoscopic display with no crosstalk and full resolution is realized by designing a butterfly-shaped liquid crystal display shutter in a multi-directional backlight unit. And the calculation formulas of parameters of the directional backlight lenticular panel are derived theoretically. Furthermore, the multi-directional backlight unit parameters of a 55 in (1 in=2.54 cm) 4K model autostereoscopic 3D displayer are presented, and they are optimized by TracePro software. The simulation results show that the crosstalk of designed autostereoscopic display is less than 0.01% which can be approximate to zero, and it can be fully compatible with the existing glasses shutter switch 3D video images with no loss of resolution..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 41201 (2017)
Unwrapping Method for Local High Density Residual Point Wrapped Phase
Guo Yuan, Yang Zhen, and Wu Quan
In order to solve the problems of phase unwrapping low precision induced by real phase loss, error transmission, and excessive smoothing while we use (0-1) mask and least square iterative method to deal with phase unwrapping of local high density residual point wrapped phase, a new phase unwrapping method is presented.In order to solve the problems of phase unwrapping low precision induced by real phase loss, error transmission, and excessive smoothing while we use (0-1) mask and least square iterative method to deal with phase unwrapping of local high density residual point wrapped phase, a new phase unwrapping method is presented. By using (2k+1)×(2k+1) sub pixel discrete Gaussian convolution kernel to mask the high density residual point region, the true phase information of the region is effectively preserved. The weight of the four directions least square iterative method is set by adjusting degree-maximum phase gradient deviation. Therefore, the over-smoothing of the least square iterative method is improved and the error propagation in the mask area is restrained. The accuracy of the phase unwrapping of the high density residual point area is effectively improved. The experimental results show that this method can solve the phase unwrapping problem of high density residual point in the local region effectively and the original phase of high density residual point can be restored quickly and effectively. Compared with the traditional least square iterative method, the average error of the high residual point region of the proposed method is only 10% comparing to least square iterative method under the same iteration times. This method is more suitable for accurate phase unwrapping of high density residual point region..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 41202 (2017)
Correcting Method and Evaluation of Eccentricity Error of Circle Target
An Jingjing, Gao Nan, Chen Chao, Liu Xiyang, and Zhang Zonghua
Circular target has been widely used in object recognition and localization, and its localization precision largely determines the precision of the 3D measurement system. In order to eliminate the eccentricity error generated by perspective projection transformation and improve the location precision of circular targetCircular target has been widely used in object recognition and localization, and its localization precision largely determines the precision of the 3D measurement system. In order to eliminate the eccentricity error generated by perspective projection transformation and improve the location precision of circular target, the eccentricity error correction of circles target has been researched, and a correction method based on the existing derivation of spatial projection is proposed. Firstly, through perspective projection transformation, the concentric circle is changed to two different ellipses with separate centers. According to the centers of two ellipses and the radius of concentric circle, the actual position of the center is calculated. Then, a concentric circle projection simulation experiment is carried out, and the relationships between eccentricity error and radius of circle as well as the rotation angle are analyzed according to the result of circle central location. Finally, a monitor is used as object plane to display the concentric circles with different parameters. And together with a camera, they constitute the experiment system to evaluate the measurement precision of circle center. The results show that this method can accurately obtain the actual projection point of concentric circular target, and the average back-projection error of the calibrated camera can be reduced to 50% after correction. Compared with previous verification methods using calibration board, the proposed method using monitor to verify the concentric circle location precision has better flexibility and practicality in operation..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 41203 (2017)
Maximum Likelihood Estimation Method to Eliminate Supporting Error in Subaperture Stitching Interferometry
Zhang Min, Gao Songtao, Miao Erlong, Sui Yongxin, and Yang Huaijiang
In order to eliminate the measurement error caused by the support of the subaperture stitching interferometry, the method of maximum likelihood estimation is proposed to calculate the deformation due to the support. The first step is to maintain the brace immobility, rotating the test lens to measure the subaperture suIn order to eliminate the measurement error caused by the support of the subaperture stitching interferometry, the method of maximum likelihood estimation is proposed to calculate the deformation due to the support. The first step is to maintain the brace immobility, rotating the test lens to measure the subaperture surface. Then, the maximum likelihood estimation method is used to calculate the deformation caused by the support. Finally, the interferometer measurement data of the subaperture surfaces subtract the estimated support surface error, and the stitching algorithm is used to splice a full aperture surface shape. The experiment results are compared with the result of the full aperture direct interferometer measurement, which shows that the method can remove the deformation caused by the support and improve the accuracy of the stitching detection..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 41204 (2017)
Method of Roadheader Position Detection Based on Image Recognition of Double Laser Targets
Zhou Lingling, Dong Haibo, and Du Yuxin
To measure the roadheader position in coal mine, a real-time detection system of roadheader position is constructed, which uses the image recognition measurement method based on double laser targets. The spatial distributions of optical feature points and feature light on the laser target are researched, and the calculTo measure the roadheader position in coal mine, a real-time detection system of roadheader position is constructed, which uses the image recognition measurement method based on double laser targets. The spatial distributions of optical feature points and feature light on the laser target are researched, and the calculation method of roadheader position based on double laser targets is presented. With digital image processing technology, the accurate parameters of feature points and feature light are obtained, thus the precise localization of reference points on target is realized. Then, the space matrix transformation method is used to calculate the roadheader position parameters. In the simulation test, an automatic test platform of body position is established. The experimental results show that when the measurement range is less than 40 m, the system displacement error is less than 2 mm, and the angle error is less than 0.5°. The measure system has such advantages as high accuracy, simple and reliable structure, and good real-time performance. Therefore, it can meet the measurement requirements well, and achieve the position monitoring of roadheader in the tunneling process in the mine..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 41205 (2017)
Application of Two-Dimensional S-Transform in Optical 3D Shape Measurement
Song Mengsa, and Chen Wenjing
As a extension of windowed Fourier transform and wavelet transform, S-transform has the features of good time-frequency characteristic and multi-resolution ability. Compared with Fourier transform which lacks local analysis ability, S-transform not only has this ability, its coefficients are also closely connected withAs a extension of windowed Fourier transform and wavelet transform, S-transform has the features of good time-frequency characteristic and multi-resolution ability. Compared with Fourier transform which lacks local analysis ability, S-transform not only has this ability, its coefficients are also closely connected with the Fourier spectra of the image to be analyzed. Therefore, S-transform has been widely used in fringe analysis in recent years. Based on the features of S-transform coefficients, the 2D S-transform "ridge" (2DSTR) method and 2D S-transform filtering (2DSTF) method are studied deeply. The two methods are compared in detail, too. The results of theoretical analysis are verified by computer simulation and experiment, and they will provide reference for the application of S-transform in 3D shape measurement..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 41206 (2017)
Geometric Parametric Study of Dual Stage Ion Optics
Jia Lianjun, Zhang Tianping, Chen Juanjuan, Jia Yanhui, and Liu Mingzheng
The goal of the study is to identify the effect of the grid geometry parameters on the performance of the ion optics design. The combination of particle-in-cell method and Monte-Carlo collision method is used to study the influence of the critical geometrical parameters on the beamlet current capability, beamlet divergThe goal of the study is to identify the effect of the grid geometry parameters on the performance of the ion optics design. The combination of particle-in-cell method and Monte-Carlo collision method is used to study the influence of the critical geometrical parameters on the beamlet current capability, beamlet divergence angle and capture of charge exchange (CEX) ions. Moreover, the variation trends of beam divergence angle and impingement CEX ion are also investigated under different specific impulse conditions. The results show that with the increase of the screen grid aperture radius, the beamlet current capability, beam divergence angle and saddle point potential are increased. An increase in the accelerator grid radius produces a decrease in impingement CEX ion current. The beamlet divergence angle and the impingement CEX ion current both increase with the incremental thickness of accelerator grid. When the specific impulse is 8000 s, the change of the acceleration stage gap has little effect on the beamlet current capability. In addition, the higher the specific impulse, the smaller the beam divergence angle and the fewer the impingement CEX ions..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 41207 (2017)
Lasers and Laser Optics
Temperature Field Simulation of Single Layer Carbon Fiber Reinforced Plastics in Parallel Laser Cutting
Yu Dongyang, and Wang Xuyue
In order to reveal the mechanism of energy absorption and transfer of materials in laser cutting of carbon fiber reinforced plastics (CFRP), a three dimensional finite element model for parallel laser cutting of single-fiber arranged CERP, a three dimensional fiber-spot diameter ratio model and a three dimensional fibeIn order to reveal the mechanism of energy absorption and transfer of materials in laser cutting of carbon fiber reinforced plastics (CFRP), a three dimensional finite element model for parallel laser cutting of single-fiber arranged CERP, a three dimensional fiber-spot diameter ratio model and a three dimensional fiber-resin double phase model are established, respectively. Numerical simulation results show that, with the decline of fiber-spot diameter ratio, the kerf width decreases from 229.45 μm to 95.60 μm, while the width of the heat affected zone (HAZ) decreases from 172.08 μm to 156.79 μm. The experimental results agree well with the simulation results, and the errors for the kerf width and the HAZ width are 5.97% and 1.13%, respectively..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 41401 (2017)
LD Side-Pumped Nd∶YVO4 532 nm Quasi-Continuous Green Laser
Cui Jianfeng, Wang Di, Zhang Ya′nan, Gao Tao, Dai Qin, and Yao Jun
The LD side-pumped Nd∶YVO4 532 nm quasi-continuous green laser is reported. The acousto-optic Q-switched operation and the laser diode side-pumped Nd∶YVO4 laser are used to get high-power linearly polarized 1064 nm laser output. High-power 532 nm green laser output is achieved by typeⅠphase-matched LiB3O5 (LBO) as secoThe LD side-pumped Nd∶YVO4 532 nm quasi-continuous green laser is reported. The acousto-optic Q-switched operation and the laser diode side-pumped Nd∶YVO4 laser are used to get high-power linearly polarized 1064 nm laser output. High-power 532 nm green laser output is achieved by typeⅠphase-matched LiB3O5 (LBO) as second harmonic generation crystal. An average output power of 23.5 W at 532 nm is obtained under the condition of input current of 30 A, the repetition rate of 20 kHz and the 1064 nm fundamental wave of 33 W. The optical-optical conversion efficiency is up to 71.2%. The pulse width is 44.3 ns and the polarization ratio is 254∶1..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 41402 (2017)
Stable and Efficient Intracavity Frequency-Doubled Cr,Nd∶YAG/GTR-KTP Self-Q-Switched Green Laser Under Direct Pumping
Lin Boxin, and Dong Jun
Employing an 885 nm laser diode (LD) as the pumping source, the stable and highly efficient performance of a Cr,Nd∶YAG/GTR-KTP intracavity frequency doubled self-Q-switched miniature green laser under end-pumping is demonstrated at room temperature by using the co-doped crystal Cr,Nd∶YAG and gray tracking resistant KTPEmploying an 885 nm laser diode (LD) as the pumping source, the stable and highly efficient performance of a Cr,Nd∶YAG/GTR-KTP intracavity frequency doubled self-Q-switched miniature green laser under end-pumping is demonstrated at room temperature by using the co-doped crystal Cr,Nd∶YAG and gray tracking resistant KTP (GTR-KTP) crystal as laser active material and frequency doubling crystal respectively. The maximum average output power of 200 mW at 532 nm is achieved when the absorbed pump power is 1.65 W, and the corresponding optical-to-optical efficiency is 12.1%. When the absorbed pump power is greater than 1.15 W, the self-Q-switched green laser pulse is achieved with the energy over 8 μJ, the pulse width 8.8 ns and the peak power over 1 kW. Effects of different Nd3+ doping concentrations on the output frequency doubling power of a Cr,Nd∶YAG/GTR-KTP intracavity frequency doubled self-Q-switched miniature green laser theoretically analyzed with the rate equations. The optimized Nd3+ doping concentration is obtained to achieve efficient green laser output. Compared with those methods generating green laser under 885 nm laser pumping, the directly pumped Cr,Nd∶YAG/GTR-KTP intracavity frequency doubling self-Q-switched green laser is demonstrated to be a more ideal laser source for compressing pulse width effectively, and it provides a new method for developing highly efficient, short-pulse miniature green laser..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 41403 (2017)
Laser Beam Propagation Process in Atmosphere
Gao Fengbin, Zhao Changming, Guan Zhe, Zhang Haiyang, Yang Suhui, and Wang Yu
One scheme of the space solar power station (SSPS) is based on the laser beam for energy transfer from space to the earth. In order to demonstrate the feasibility of laser energy transfer, the analysis of the propagation process of laser beam in atmosphere is needed. Modeling and simulating processes are conducted. We One scheme of the space solar power station (SSPS) is based on the laser beam for energy transfer from space to the earth. In order to demonstrate the feasibility of laser energy transfer, the analysis of the propagation process of laser beam in atmosphere is needed. Modeling and simulating processes are conducted. We analyze the effect of atmosphere towards laser beam at different heights, simulate the intensity profile of laser beam, and discuss the change of atmospheric temperature and refractive index at different heights. The results show that in order to reduce influence of atmosphere and avoid energy loss, the laser power density should remain within a certain range. Increasing the laser beam size can reduce the laser power density at a certain power level..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 41404 (2017)
Effect of Laser Shock Peening on Residual Stress and Microstructure of TC17 Titanium Alloy
Sun Hao, Zhu Ying, Guo Wei, Peng Peng, and Huang Shuai
Laser shock peening (LSP) with different process parameters is applied on TC17 titanium alloy, the distribution of the residual stress of TC17 titanium alloy after LSP is tested, and the microstructure is observed by transmission electron microscopy. The results show that, the surface residual stress of TC17 titanium aLaser shock peening (LSP) with different process parameters is applied on TC17 titanium alloy, the distribution of the residual stress of TC17 titanium alloy after LSP is tested, and the microstructure is observed by transmission electron microscopy. The results show that, the surface residual stress of TC17 titanium alloy after LSP increases with the increase of impact number and pulse energy. Severe plastic deformation and high density dislocation are found on TC17 titanium alloy surface after LSP. The density of dislocation increases with the increase of laser impact number and pulse energy..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 41405 (2017)
Study on Energy Distribution of Non-Vertical Laser Cutting
Ou Changjin, Qin Caibao, Jiang Xianfeng, and Dong Xingtao
In order to realize non-vertical laser cutting of polymer materials, a non-vertical laser cutting model is established. The change laws of kerf width and heat affected zone (HAZ) width with the laser line energy, the incident angle and the defocusing amount are obtained by solving the threshold value energy equation. IIn order to realize non-vertical laser cutting of polymer materials, a non-vertical laser cutting model is established. The change laws of kerf width and heat affected zone (HAZ) width with the laser line energy, the incident angle and the defocusing amount are obtained by solving the threshold value energy equation. In the continuous CO2 laser cutting system, the cutting experiment is done on polyethylene terephthalate (PET) film with the orthogonal experimental method. It is found that the kerf width and the HAZ width change gently and the cutting quality is good when the incident angle is in the range of -57.3° to 57.3° and the defocusing amount is in the range of -15 mm to 15 mm. The results show that this model can accurately predict kerf width and HAZ width in non-vertical laser cutting of polymer materials, which provides parameter guidance in laser cutting of complex films with curved faces..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 41407 (2017)
Microstructure and Property of 9Ni Steel Joint by Ultra-Narrow-Gap Fiber Laser Welding
Tian Shuqiang, Li Zhuguo, and Hua Xueming
By using YLS-10000 fiber lasers and ERNiMo-8 filler wire, the ultra-narrow-gap laser welding of 9Ni steel for liquid container of liquefied natural gas (LNG) vessels is conducted and the microstructure and property of the welded joint are studied. The results show that, the ultra-narrow-gap welded joint with good fusioBy using YLS-10000 fiber lasers and ERNiMo-8 filler wire, the ultra-narrow-gap laser welding of 9Ni steel for liquid container of liquefied natural gas (LNG) vessels is conducted and the microstructure and property of the welded joint are studied. The results show that, the ultra-narrow-gap welded joint with good fusion sidewalls can be obtained by optimizing weld parameters. The microstructure of weld is austenite, and crystallization morphology on two sides is columnar crystal, while that at center is equiaxed crystal. The heat affected zone (HAZ) is clearly divided into coarse grain zone and fine grain zone, and both of their microstructures are martensite and a small amount of residual austenite, where the average hardness is about 340 HV, much higher than that of the base metal (230 HV) and that of the weld (200 HV). Fractures occur on welds of tensile test specimens, and the tensile strength of the joint is slightly lower than that of the base metal. The low-temperature impact energy of the joint increases with its distance from the weld center increase, with an average value of above 70 J. The fracture morphology is always tiny dimple and the fracture of the joint is ductile..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 41408 (2017)
Effect of Laser Welding Process on Weld Formation and Mechanical Property of GH188 Alloy
Lu Wei, Ma Xuyi, Gong Shuili, and Yang Jing
The effect of laser welding process on the weld formation and mechanical property of GH188 alloy weld joint is studied. The results show that a high laser power or a low welding speed is disadvantageous for the weld formation of GH188 alloy, there exists the phenomenons of spatter and slight undercut on the weld back, The effect of laser welding process on the weld formation and mechanical property of GH188 alloy weld joint is studied. The results show that a high laser power or a low welding speed is disadvantageous for the weld formation of GH188 alloy, there exists the phenomenons of spatter and slight undercut on the weld back, and the grain in weld zone of joint is coarse and the tensile strength of joint is low. With the increase of welding speed, the weld width and the spatter on the weld back both decrease. With the increase of laser power, the weld width and the spatter on the weld back both increase. When the laser power is in the range 2.8-3.2 kW and the welding speed is 6 m/min, the weld formation and tensile property of weld joint are both good..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 41409 (2017)
Surface Quality and Property of Copper Treated by Laser Shock Peening
Wang Feng, Zuo Hui, Zhao Li, and Chen Mei
In order to study the effects of laser shock peening (LSP) on surface quality and property of copper, Nd∶YAG lasers is used to treat copper samples by laser shock peening. The experimental results show that, when the polymer black tape is used as the absorption layer, there are no defects on the surface morphology of sIn order to study the effects of laser shock peening (LSP) on surface quality and property of copper, Nd∶YAG lasers is used to treat copper samples by laser shock peening. The experimental results show that, when the polymer black tape is used as the absorption layer, there are no defects on the surface morphology of sample. With the increase of the overlap rate, the maximum hardness increases and the surface roughness decreases. The effects on the affected layer depth and the maximum hardness of sample caused by the overlapped and the staggered shock ways of two shocks are similar. The simulation results show that the staggered shock way can enhance the residual compressive stress of sample..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 41410 (2017)
Laser Spot Drift Characteristics Based on Bayesian Inference
Zhu Dongji, Cai Hongwei, and Gao Rong
Aiming at the problems that the laser spot drift is affected by many kinds of interference factors, and the measurement accuracy is difficult to estimate, the method of spot drift characteristic analysis based on Bayesian inference is put forward. On the basis of strict Bayes theorem deduction, the analysis of laser fuAiming at the problems that the laser spot drift is affected by many kinds of interference factors, and the measurement accuracy is difficult to estimate, the method of spot drift characteristic analysis based on Bayesian inference is put forward. On the basis of strict Bayes theorem deduction, the analysis of laser fundamental mode characteristics and the influence of measurement noise on ideal spot drift, the thorough mathematical model of the spot drift characteristics based on Bayesian inference is constructed and the parameters are determined strictly. The simulation results and the theoretical analysis are in good agreement. The method can be used to evaluate the influence of the environment, such as thermal effect, environmental vibration and air disturbance, on the laser drift..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 41411 (2017)
Thermal Fatigue Performance Test of Casting Roller Sleeve Material Heated by Laser Scanning
Liu Xiaobo, Wang Zhitong, and Li Wen
By using Nd∶YAG continuous laser as the heat resource to scan and heat the surface of the casting roller sleeve material 32Cr3Mo1V, the thermal fatigue performance is tested by contact cooling the back of the sample. The laser absorptivity of the sample with different surface roughness and oxidation state is measured wBy using Nd∶YAG continuous laser as the heat resource to scan and heat the surface of the casting roller sleeve material 32Cr3Mo1V, the thermal fatigue performance is tested by contact cooling the back of the sample. The laser absorptivity of the sample with different surface roughness and oxidation state is measured with the lumped parametric method. The temperature cycle and compressive stress condition of the sample surface are simulated by numerical calculation. The results show that, after 1000 thermal cycles, cracks appear in the ablation hole and at positions with rough scratches on the sample surface. When the thermal cycle ranges from 1000 to 2000, the length of the crack is linearly related to the number of thermal cycles. Because the proposed method ignores the effects of mechanical stress and aluminum liquid on the roller sleeve, the growth rate of the crack length obtained from the test is only half of the actual one..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 41412 (2017)
Microscopy
Super-Resolution Imaging of Pupil Filter Using Deformable Mirror
Zhao Lina, Dai Yun, Zhao Junlei, Xiao Fei, Zhao Haoxin, Zhang Xiaojun, and Zhou Xiaojun
In this paper, a deformable mirror is employed as a pupil filter in a super-resolution imaging system because it can be used to modulate optical field phase quickly and flexibly. The genetic algorithm is adopted to design pupil phase structures with different super-resolution parameters, and the closed-loop phase fittiIn this paper, a deformable mirror is employed as a pupil filter in a super-resolution imaging system because it can be used to modulate optical field phase quickly and flexibly. The genetic algorithm is adopted to design pupil phase structures with different super-resolution parameters, and the closed-loop phase fitting of pupil filter is realized by modifying the closed-loop reference matrix of the adaptive optics system. On this basis, the experiments are conducted to compare the super-resolution imaging results with different pupil filter situations. The experimental results show that the deformable mirror can well fit the designed phase of pupil filter and the super-resolution imaging parameters are in agreement with theoretical predictions. The deformable mirror processes phase fitting of super-resolution pupil by employing reflective type and controlling mirror′s shape. This method has no requirement of polarization state of incident light, and it is in favor of practical application..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 41801 (2017)
Nonlinear Optics
Theoretical Study on Broadband Frequency Doubling in Aperiodically Poled Lithium Niobate Crystal
Jiang Jian, Zhang Jiandong, Wang Kai, Xiao Xuan, and Zhang Zuxing
Broadband quasi-phase-matching (QPM) is widely used in many fields, such as multi-wavelength and ultrashort pulse frequency doubling. The conditions of QPM and group velocity matching in lithium niobate crystal are analyzed. The optimized structure of aperiodically poled lithium niobate (APPLN) crystal is designed by gBroadband quasi-phase-matching (QPM) is widely used in many fields, such as multi-wavelength and ultrashort pulse frequency doubling. The conditions of QPM and group velocity matching in lithium niobate crystal are analyzed. The optimized structure of aperiodically poled lithium niobate (APPLN) crystal is designed by genetic algorithm. Also, we present a method of optimizing the APPLN crystal second-harmonic generation (SHG) bandwidth by appropriately adjusting the position and quantity of the fundamental wavelengths. The results show that for QPM of type 0 (e+e→e) near the group velocity matching points, the SHG bandwidth in periodically poled lithium niobate (PPLN) crystal is about 167 nm, while the maximum SHG bandwidth in APPLN is up to 440 nm, and the bandwidth increases by 273 nm. For QPM of type I (o+o→e) near the group velocity matching points, the SHG bandwidth in PPLN is about 59 nm, while the maximum SHG bandwidth in APPLN is up to 153 nm, and the bandwidth increases by 94 nm..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 41901 (2017)
Optical Devices
Investigation on Thermo-Induced Nonlinearity of Fiber Fabry-Perot Filter by Using Optical Fiber Sensing System
Sheng Wenjuan, Zhang Hui, Yang Ning, Liu Yang, and Peng Gangding
The thermo-induced nonlinearity of piezo-electrical transducer (PZT) driven fiber Fabry-Perot (FFP) filter using fiber Bragg grating (FBG) sensing system is investigated and evaluated. Polynomial fitting is adopted to model the nonlinearity. Under 4th or higher order polynomial fitting and a reference FBG, the thermo-iThe thermo-induced nonlinearity of piezo-electrical transducer (PZT) driven fiber Fabry-Perot (FFP) filter using fiber Bragg grating (FBG) sensing system is investigated and evaluated. Polynomial fitting is adopted to model the nonlinearity. Under 4th or higher order polynomial fitting and a reference FBG, the thermo-induced strain error is reduced from 750 με to 15 με and the standard deviation is kept below 10 με while PZT driven FFP experiences over 15 ℃ temperature change. It is observed that thermal effect on PZT driven FFP is not simply invariable or linear in a wide temperature range..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 42301 (2017)
Optics at Surfaces
Coupling Surface Plasmon Polaritons into Beams in Free Space
Yin Juan, and Chen Yuegang
Transmission control of the plasma on the metal surface in optical integration is very important. Structures are designed to couple the surface plasmon polaritons (SPPs) to the light wave in free space by surface wave holography. Interference light intensity is obtained through simulating the scalar superposition of thTransmission control of the plasma on the metal surface in optical integration is very important. Structures are designed to couple the surface plasmon polaritons (SPPs) to the light wave in free space by surface wave holography. Interference light intensity is obtained through simulating the scalar superposition of the SPP wave beam and the target beam in free space. Groove structures are obtained by etching grooves at the maximum light intensity positions. When the SPP waves are incident to the designed structures, the grooves scatter the SPP waves into free space and then the waves superpose there, generating the required light beam. Based on the principle, two structures are designed for coupling the SPP waves to focus on one or two specified points in free space. The finite-difference time-domain method is used to verify the principle. This coupled manner can be used as a method for solving the detection problem in the surface plasmon integrated optics. The SPP signal is coupled into free space and detected by common photodetectors..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 42401 (2017)
Reviews
Quantitative Phase Microscopy Imaging Based on Ptychography
Pan An, Zhang Yan, Zhao Tianyu, Wang Zhaojun, Dan Dan, Shi Yishi, and Yao Baoli
As one novel lensless phase retrieval technique, ptychography greatly improves the convergence speed and the anti-noise capability of traditional phase iterative retrieval algorithms. Ptychography features a lot of merits, such as large field of view, high contrast, high resolution, and label-free as well as long workiAs one novel lensless phase retrieval technique, ptychography greatly improves the convergence speed and the anti-noise capability of traditional phase iterative retrieval algorithms. Ptychography features a lot of merits, such as large field of view, high contrast, high resolution, and label-free as well as long working distance without losing low frequency phase component, which has been widely applied in various regions. The research status and the latest advances in the field of quantitative phase microscopy imaging are introduced, especially the fundamentals, technique advances and related applications of conventional ptychography (CP) and Fourier ptychography (FP). The fast FP and the fluorescence microscopy imaging based on FP are mainly discussed and the current problems and future trends of CP and FP are also summarized..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 40001 (2017)
Graphene-Based Optical Fiber and Its Applications
Bi Weihong, Ma Jingyun, Yang Kaili, Tian Pengfei, Wang Xiaoyu, and Li Caili
Graphene attracts much attention in recent years due to its unique energy band structure and excellent electro-optical properties. One of the important researches is the graphene optical fiber which is consist of graphene and optical fiber. The structure and basic properties of graphene are introduced. Graphene, which Graphene attracts much attention in recent years due to its unique energy band structure and excellent electro-optical properties. One of the important researches is the graphene optical fiber which is consist of graphene and optical fiber. The structure and basic properties of graphene are introduced. Graphene, which is with a two-dimensional honeycomb lattice structure composed of single-layer carbon atoms which are formed by the close stacking of sp2 hybird orbital, shows excellent properties in machinery, electrology, optics and thermodynamics because of its unique energy band structure with zero band gap. The research progress of graphene-based optical fiber devices at home and abroad is briefly reviewed. The working principle and device characteristics of lasers, modulators, surface plasmon resonance sensors and polarizers based on graphene optical fiber are described. The current problems and future development trends of graphene optical fiber are analyzed..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 40002 (2017)
Laser Emission on Two-Dimensional Transition Metal Dichalcogenides
Zheng Ting, Nan Haiyan, Wu Zhangting, and Ni Zhenhua
Two-dimensional transition metal dichalcogenides (TMDs) such as MoS2 have different optical and electrical properties with the change of thickness and layer number, and exhibit unique excitonic behavior and high optical quantum efficiency, thus they have great potential applications in optoelectronic devices. Recently,Two-dimensional transition metal dichalcogenides (TMDs) such as MoS2 have different optical and electrical properties with the change of thickness and layer number, and exhibit unique excitonic behavior and high optical quantum efficiency, thus they have great potential applications in optoelectronic devices. Recently, there are great progresses on the studies of optical properties and related optoelectronic devices of TMDs. For example, the photoluminescence (PL) of TMD materials can be modulated through the electric field, chemical doping and defects engineering, and the PL quantum efficiency is greatly enhanced. The LEDs based on lateral and vertical heterojunctions stacked by TMD materials are extensively investigated and the high light emission efficiency is demonstrated. The laser emission with low threshold is also realized using TMDs as gain medium and integrated with micro disk and photonic crystals. This review starts from the structures and optical properties of TMDs, summarizes PL modulation methods and effects of TMD materials, introduces the research progresses of laser emission of TMDs, and finally the laser future development based on TMDs is prospected..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 40003 (2017)
Variable Aberration Compensation Techniques in Wavefront Interferometry
Chen Shanyong, Lu Jinfeng, and Xue Shuai
Complex surfaces typically including aspheres are more and more widely used in modern optical systems. Better imaging quality can be achieved with fewer elements because aspheres provide more design freedom. However, the variety of aspheres also introduces challenges to surface metrology. Conventional null tests do notComplex surfaces typically including aspheres are more and more widely used in modern optical systems. Better imaging quality can be achieved with fewer elements because aspheres provide more design freedom. However, the variety of aspheres also introduces challenges to surface metrology. Conventional null tests do not have the flexibility to adapt to different shapes. Therefore variable aberration compensation techniques are important to enhance the flexibility and efficiency of testing. The analysis of partial null lens, combination of phase plates and high-order aspheric singlet for variable compensation schemes of spherical aberration of rotationally symmetric aspheres is presented. For aberration compensation of off-axis aspheres, the variable compensation schemes of tilted spherical mirror system, Risley prisms and the counter-rotating phase plates are analyzed. Furthermore, the progress of using deformable mirrors and spatial light modulators (SLM) as programmable compensators in wavefront interferometry is reviewed. Finally, three major problems in variable aberration compensation techniques are introduced, which are compensation of wide range and multiple modes of aberration, retrace error compensation and decoupling of misalignment-induced aberration..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 40004 (2017)
Three-Dimensional Micro- and Nano-Machining Based on Spatiotemporal Focusing Technique of Femtosecond Laser
Jing Chenrui, Wang Zhaohui, and Cheng Ya
The fundamental principle of spatiotemporal focusing technique of femtosecond laser is introduced in this paper, and applications of this technique on improving the resolution of femtosecond laser fabrication, suppressing the nonlinear effect of the fabricating process, and improving the materials fabrication quality aThe fundamental principle of spatiotemporal focusing technique of femtosecond laser is introduced in this paper, and applications of this technique on improving the resolution of femtosecond laser fabrication, suppressing the nonlinear effect of the fabricating process, and improving the materials fabrication quality are reviewed. Discussion is emphasized on the unique optical field characteristics of spatiotemporally focused femtosecond laser pulses including pulse front tilt (PFT) and intensity plane tilt, and their influence on material processing. Moreover, the applications of spatiotemporal focusing technique on high field physics and its scope of applications are introduced. Lastly, we summarize the principles and applications of spatiotemporal focusing technique, and suggest several directions for the future research..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 40005 (2017)
Progress in Cross Sensitivity of Fiber Bragg Grating Sensor
Sun Shiqing, Chu Fenghong, and Lu Jiayan
The changes of external factors such as temperature and strain can cause the center wavelength drift of fiber Bragg grating (FBG) reflection wave. Strain cannot be directly measured according to the center wavelength drift in strain sensing measurement. The problem of temperature and strain cross sensitivity seriously The changes of external factors such as temperature and strain can cause the center wavelength drift of fiber Bragg grating (FBG) reflection wave. Strain cannot be directly measured according to the center wavelength drift in strain sensing measurement. The problem of temperature and strain cross sensitivity seriously restricts the measurement precision and the application of FBG sensor, which hinders the sensing monitoring technology to be practical. Many researchers have proposed various solutions to eliminate the influence of temperature according to different algorithms, materials, packaging structures, and so on. According to the different methods of temperature processing, the solutions can be divided into temperature separation method and temperature compensation method. The advantage and disadvantage of each method are analyzed..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 40006 (2017)
Spectroscopy
Terahertz Spectroscopy of the Interfacial Water in Phospholipid Membranes
Pan Yatao, and Lü Junhong
Interfacial water plays an important role in the function of biological membranes. However, due to the significant absorption of water on the terahertz wave, it is very difficult to obtain the terahertz transmission spectra of the membrane interfaces. Herein, we develop a system to study the membrane interfacial water Interfacial water plays an important role in the function of biological membranes. However, due to the significant absorption of water on the terahertz wave, it is very difficult to obtain the terahertz transmission spectra of the membrane interfaces. Herein, we develop a system to study the membrane interfacial water by combining the preparation of water droplets in lipid and terahertz time domain spectroscopy. It only needs a few biological samples but has high sensitivity of water state in this method. Based on this system, we have successfully measured the terahertz dielectric spectra of kinds of lipid emulsions. The results revealed that the hydration state and water dynamics upon the membrane interface are dependent on the lipid headgroup components..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 43001 (2017)
Ultrafast Optics
Design of Traveling-Wave Deflector for High Speed Streak Camera
Zong Fangke, Lei Baoguo, Gu Li, Zhang Jingjin, Guo Baoping, and Yang Qinlao
To meet the special demands on the deflector of femtosecond streak tube camera, a kind of traveling-wave deflector for the high speed streak camera is designed. According to the design theory of traveling-wave deflector proposed by Finch, the design process is simplified and a deflector model is built by using the HFSSTo meet the special demands on the deflector of femtosecond streak tube camera, a kind of traveling-wave deflector for the high speed streak camera is designed. According to the design theory of traveling-wave deflector proposed by Finch, the design process is simplified and a deflector model is built by using the HFSS software. The high frequency characteristics and the pass bandwidth of the traveling-wave deflector are simulated and solved. The basic structural parameters are determined by matching the electromagnetic wave phase velocity with the electron beam velocity. Through the above method, a traveling-wave deflector is optimally designed for the high speed streak camera with the electron energy of 10 kV. The traveling-wave deflector is designed with the length of 44 mm, the plate spacing of 4 mm, the pass bandwidth of 4 GHz, and the deflection sensitivity of 119.8 mm/kV. The traveling-wave deflector is tested with the existing high-speed streak camera. The test results show that the design results are accurate and reliable, and the design method is proper. The work provides an effective way to design the traveling-wave deflector for the tube camera，and it can shorten the development cycle of high resolution scanning camera..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 4, 43201 (2017)
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