Journals >Infrared and Laser Engineering
Contents
2017
Volume: 46 Issue 9
48 Article(s)
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[in Chinese]
Multispectral visual image processing method based on adaptive regulation of humanoid eye
Song Yanming, Pan Zhikang, Meng Xiaochen, Lou Xiaoping, and Zhu Lianqing
Aiming at the single character of target image acquisition in the traditional bionic vision system, multispectral visual image processing method based on adaptive regulation of humanoid eye was proposed. Firstly, the improved automatic focusing algorithm was used to collect the high resolution image of visible light anAiming at the single character of target image acquisition in the traditional bionic vision system, multispectral visual image processing method based on adaptive regulation of humanoid eye was proposed. Firstly, the improved automatic focusing algorithm was used to collect the high resolution image of visible light and the low resolution image of near-infrared light. In the multispectral imaging system, there were different problems of visible and near-infrared image resolution under fixed focal length due to different refractive index of spectral prism. The improved two-generation wavelet transform was adopted to enhance the image contrast and improve the visual effect. Finally, the performance of automatic focus algorithm and image enhancement algorithm was verified by using a multi-spectral experimental device based on liquid zoom lens. The experimental results indicate that the average time of effective auto focusing system is 756 ms, and the gray variance function value increases by 79.4% after near infrared image enhancement, which solves the problem of low contrast and fuzzy details and realizes adaptive regulation..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 910001 (2017)
Development of bionic moth-eye anti-reflective conical micro-nano structure
Guo Xudong, Dong Tingting, Fu Yuegang, Chen Chi, and Wen Chunchao
The finite difference time domain(FDTD) method was adopted for simulation of the conical bionic moth-eye micro-nano structure on silicon substrate in middle infrared band(3-5 μm). A parameter-optimized combination of the micro-nano structure which was of low reflection was obtained by analyzing the parameters of the miThe finite difference time domain(FDTD) method was adopted for simulation of the conical bionic moth-eye micro-nano structure on silicon substrate in middle infrared band(3-5 μm). A parameter-optimized combination of the micro-nano structure which was of low reflection was obtained by analyzing the parameters of the micro-nano structure, such as fill factor, period and etching depth. In order to guide the actual processing better, tolerance analysis of different parameters was carried out. The binary exposure and reactive ion etching technology were applied to fabricate the conical bionic moth-eye micro structure on silicon substrate in processing. The surface topography of the micro structure was acquired by thermal field emission scanning electron microscopy. The test of the silicon wafer with single-sided micro structure polishing by the infrared imaging spectrometer demonstrates that the reflectivity of the bionic moth-eye micro structure vibrates approximately 5% in middle infrared band..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 910002 (2017)
[in Chinese]
Review of fringe-projection profilometry and phase measuring deflectometry
Liu Dong, Yan Tianliang, Wang Daodang, Yang Yongying, and Huang Wei
Fringe-projection profilometry and phase measuring deflectometry can realize high accurate measurement of three-dimensional shape, which has good development prospect in the full field three-dimensional profilometry. First, the measuring principles of fringe-projection profilometry and phase measuring deflectometry werFringe-projection profilometry and phase measuring deflectometry can realize high accurate measurement of three-dimensional shape, which has good development prospect in the full field three-dimensional profilometry. First, the measuring principles of fringe-projection profilometry and phase measuring deflectometry were introduced. Moreover, the technologies of phase extracting and camera calibration in fringe-projection profilometry and phase measuring deflectometry were also especially emphasized, which were key technologies. Then the similarities and differences of fringe-projection profilometry and phase measuring deflectometry were compared. What′s more, the development direction and problems to be solved of enhancing the measurement accuracy and speed in fringe-projection profilometry and phase measuring deflectometry were introduced. In order to improve the measurement accuracy, main methods can be divided as follows: correcting the the Gamma effect of a digital projector and a digital camera, improving the phase extraction accuracy of the fringes, enhancing the camera calibration accuracy, phase-height/gradient calibration accuracy and other means. In order to improve the measurement speed, the phase extraction speed and the phase unwrapping speed were improved..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 917001 (2017)
Characteristis research of diffuser panel in near backscatter measurement system
Han Yang, He Junhua, Yan Yadong, and Wu Bingjing
Based on the analysis of near back scattered light in laser fusion, a method was proposed to collect near back scattered light by using diffuser panel. Based on the analysis of the application scenarios of the diffuser panel, the characteristic of the diffuser panel was presented. A device for measuring the characterisBased on the analysis of near back scattered light in laser fusion, a method was proposed to collect near back scattered light by using diffuser panel. Based on the analysis of the application scenarios of the diffuser panel, the characteristic of the diffuser panel was presented. A device for measuring the characteristics of diffuser panel was set up. The directional hemispherical reflectance(DHR), bidirectional reflectance distribution function, surface uniformity, vacuum and UV properties were measured and analyzed. The analysis results show that the F4 target panel has a high reflectivity close to 0.99, the spectral flatness, the bidirectional reflectance distribution function(BRDF) of approximate cosine distribution, 0.869 6% of the higher surface uniformity, as well as the smaller UV vacuum influence. Therefore, the F4 target panel meets the measurement requirements of the near back scattered light in laser inertial confinement fusion (ICF), and it is feasible to use the diffuser panel to collect the near back scattered light..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 917002 (2017)
Revised system calibration method of analogy binocular based on fringe projection profilometry
Dai Shijie, Fu Jinsheng, Zhang Huibo, and Wang Zhiping
System calibration is a key procedure in fringe projection profilometry. The system calibration method of analogy binocular which regards projector as camera has the advantages of simple operation, high precision and high flexibility. Based on this method, a calibration method for accuracy enhancement of measurement sySystem calibration is a key procedure in fringe projection profilometry. The system calibration method of analogy binocular which regards projector as camera has the advantages of simple operation, high precision and high flexibility. Based on this method, a calibration method for accuracy enhancement of measurement system was presented. According to the extracted center coordinates of circle marks onto calibration board, the images for camera calibration which included the corresponding cross marks, were generated by a computer to avoid the influence of circle mark profile on corner extraction and improve camera calibration accuracy. In the meanwhile, the theoretical expression of fast calculating projector Gamma for phase correction was derived. Then pixel-to-pixel mapping between projector and camera can be accurately set up for projector calibration accuracy enhancement. Combined with the calibration results of projector and camera, it need establish unified world coordinate system for system calibration. The experiment results show by using the above calibration method, the calibration precisions of projector and camera can achieve 0.25 and 0.15 pixel, respectively, and the precision of a cuboid block measured can achieve 0.142 7 mm at the same time..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 917003 (2017)
Surface emissivity and the environment transmittance calibration for QFN package with thermal imager
Yuan Yue, Yu Huiping, Qin Fei, An Tong, and Chen Pei
Using infrared thermal imager calibrated the epoxy molding compound(EMC), copper, copper joints surface emissivity of not separated QFN package within 40-200 ℃, using the above three surface calibrated the air transmittance. The results show that the direct calculation method and direct adjustment method can be well apUsing infrared thermal imager calibrated the epoxy molding compound(EMC), copper, copper joints surface emissivity of not separated QFN package within 40-200 ℃, using the above three surface calibrated the air transmittance. The results show that the direct calculation method and direct adjustment method can be well applied in the calibration of EMC, direct calculation method can be well applied in the calibration of copper joints and copper solder. The emissivity calibration results of EMC is in 0.97 or so; the emissivity calibration results of copper joints with a linear change from 0.17 to 0.35 when the temperature increased; the emissivity calibration value of copper surface increased after the first stabled. The air transmittance calibration value of EMC surface and copper joints were around 100%, fluctuated less than 2%. The experimental results could provide some corresponding parameters for infrared termograph during the process measuring QFN using temperature and cutting separation temperature..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 917004 (2017)
Improvement research on SLR data deviation by using polarization technology for energy regulation
Deng Huarong, Wu Zhibo, Li Pu, Tang Kai, and Zhang Haifeng
Improving SLR observation data deviation has an important role in promoting application of millimeter precision satellite laser ranging technology in global geodetic observation system. The error of system time-delay calibration is the main reason of producing SLR observation data deviation. In the affecting factors, tImproving SLR observation data deviation has an important role in promoting application of millimeter precision satellite laser ranging technology in global geodetic observation system. The error of system time-delay calibration is the main reason of producing SLR observation data deviation. In the affecting factors, the system difference between target measurement and satellite laser ranging and time walk effects of detector for echo intensity in single photon detection are the mainly ones. On the platform of SLR system in Shanghai Astronomical Observatory, the differences of system delay and laser echo intensity in two measurement modes were analyzed and corrected. Laser polarization property was made use of, polarization technology of half wave plate-polarizer combination for energy regulation was applied, and optical path "zero difference" switch and echo intensity of real-time control in two measurement modes were implemented. The technology effectively reduces the light path difference and time walk effects of detector, and data improvement was about 10-20 mm which has met SLR international quality standard. The technology can also be used for backscatter avoidance in high repetition rate laser ranging, improve the echo numbers and have the good value for popularization and application..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 917005 (2017)
Measurement of temperature and concentration sensing characteristics based on dual-grating cascade structure
Zhang Wen, Liu Xiaolong, He Wei, Lou Xiaoping, and Zhu Lianqing
A dual-grating cascade structure based on long period fiber grating (LPFG) cascaded with fiber Bragg grating (FBG) for temperature and concentration measurement has been proposed. The proposed fiber sensor was cascaded by LPFG micromachined by the femtosecond laser and FBG, and the transmission spectrum has two valleysA dual-grating cascade structure based on long period fiber grating (LPFG) cascaded with fiber Bragg grating (FBG) for temperature and concentration measurement has been proposed. The proposed fiber sensor was cascaded by LPFG micromachined by the femtosecond laser and FBG, and the transmission spectrum has two valleys, namely FBG valley at 1 551.9 nm and LPFG valley at 1 560.5 nm. The temperature and concentration sensing characteristics of the proposed sensor were measured at 30-50 ℃ and 3%-30%, respectively. The experimental results show that when the temperature rises, the FBG shows red shift with increasing wavelength, the sensitivity is 26.36 pm/℃, and the linearity is 0.950 8; on the contrast, the LPFG shows blue shift with decreasing wavelength, the sensitivity is -24.55 pm/℃, and the linearity is 0.914 2. When the temperature falls, the FBG shows blue shift with decreasing wavelength, the sensitivity is 25.00 pm/℃, and the linearity is 0.945 8; the LPFG shows red shift with increasing wavelength, the sensitivity is -21.82 pm/℃, and the linearity is 0.921 2. The FBG is not sensitive to the concentration variation. When the glucose concentration rises from 3% to 30%, the LPFG shows blue shift with decreasing wavelength, the sensitivity is 196.36 pm, and the linearity is 0.956 5. The proposed sensor has high sensitivity and good linearity for dual-parameter measurements..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 917006 (2017)
Effect of infrared light source parameters on photoelectric encoder
Lu Xinran, Song Lu, and Wan Qiuhua
Infrared diodes are important components of photoelectric encoder, the orthogonality and sine of Moire fringe directly affect the segmentation accuracy and resolution of photoelectric encoder, and they affect the light source parameters. According to the investigation, the divergence angle and the width of light sourceInfrared diodes are important components of photoelectric encoder, the orthogonality and sine of Moire fringe directly affect the segmentation accuracy and resolution of photoelectric encoder, and they affect the light source parameters. According to the investigation, the divergence angle and the width of light source exert a tremendous influence in signal of encoder. Firstly, the effect of light source on the grating signal flux was analyzed. The application of the frequency domain method helped deduce the function of light transmission feature; Then the impact of the two different light source on the signal creation with a yard plate and the contrast ratio was computed; Finally, orthogonality and sinusoidal property of the Moiré stripe signal were simulated at MATLAB environment. The result shows that the encoder accuracy difference between them reached 30% by applying different source. Higher harmonic proportion of the improved decoder decreases significaitly and the signal stability is better. Studying the light source parameters has great significance in extracting the Moire fringe of high quality, and offers valuable reference for designing high-precision encoder..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 917007 (2017)
Experiment on protection performance of two-layer plasma to 6 GHz high-power microwave
Liu Yang, Shi Jiaming, Cheng Li, Li Zhigang, Zhang Jikui, and Zeng Jie
For the safety of electronic equipment, a two-layer barrier of cylindrical plasma array was designed to block high-power microwave(HPM). The reasonable parameters of plasma column in this experiment was designed and prepared, the diameter of single column were 25.4 mm, the length of it was 600 mm, and the plasma frequeFor the safety of electronic equipment, a two-layer barrier of cylindrical plasma array was designed to block high-power microwave(HPM). The reasonable parameters of plasma column in this experiment was designed and prepared, the diameter of single column were 25.4 mm, the length of it was 600 mm, and the plasma frequency and collision frequency were tunable according to the experiment′s need. The influence of microwave polarization, the plasma electron density, and number of the discharge unit on the performance of protection to HPM were analyzed and tested. The results indicate that the protection effect of plasma array with TM polarization is better than it with TE polarization when there is no nonlinear effect. The energy attenuation value can reach 20.9 dB and 14.7 dB respectively. The microwave transmission power decreased with the increasing of electron density to improve the protection effect. The results also show that transmission attenuation of HPM in two-layer structure is two times greater than it in one-layer structure because of the interlayer reflection..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 917008 (2017)
Multi-point full range monitoring of methane based on TDLAS technology
Li Zhe, Zhang Zhirong, Sun Pengshuai, Xia Hua, Luo Yuanmin, Pang Tao, and Dong Fengzhong
Methane is a dangerous gas for humans and ambience, and methane gas leak detection is especially significant in colliery, petrochemical, gas tank zone, gas station as well as any other safe fields. The fundamental of Tunable Diode Laser Absorption Spectroscopy(TDLAS) was introduced, the center wavelength at 1 653.72 nmMethane is a dangerous gas for humans and ambience, and methane gas leak detection is especially significant in colliery, petrochemical, gas tank zone, gas station as well as any other safe fields. The fundamental of Tunable Diode Laser Absorption Spectroscopy(TDLAS) was introduced, the center wavelength at 1 653.72 nm was selected for the absorption of methane detection. Also, a 14 cm optical path reflection cell with micro-lenses was designed. The on-line detection system was tested with the 0-100% methane. And also, it can be used to monitor different positions with a beam splitter. In order to improve the signal-noise ratio(SNR), wavelet transform was used to reduce noise of absorption signals. The detection limit was 335 ppm(1 ppm=10-6). A comparison results between the homemade multi-point full-range laser methane sensor and the commercial infrared gas detector were proved that the system has many advantages to meet the requirements of the majority of industry monitoring, such as: the good stability, full range, fast response, calibration free, safe latent, anti-electric magnetic interference, low cost etc..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 917009 (2017)
[in Chinese]
Large-diameter high-efficiency diffractive Fresnel membrane elements for space telescope
Wang Ruoqiu, Zhang Zhiyu, Xue Donglin, and Zhang Xuejun
For the purpose of fabricating large aperture, light-weighted, and high efficiency diffractive elements, the design of microstructure and fabrication technology of diffractive Fresnel membrane elements were proposed. A 4-step diffractive membrane with 320 mm diameter and F/#100 was designed by Zemax software. The contiFor the purpose of fabricating large aperture, light-weighted, and high efficiency diffractive elements, the design of microstructure and fabrication technology of diffractive Fresnel membrane elements were proposed. A 4-step diffractive membrane with 320 mm diameter and F/#100 was designed by Zemax software. The continuous phase distribution was transformed into discrete steps by Matlab software. The fabrication processing chain of membrane diffractive element was studied. Using polyimide film as membrane material and fused silica as substrate, the PI membrane with thickness of 20 μm was fabricated through multi-times spin-coating. The mechanical structure of membrane fixture was designed by using Solidworks software. The measurement results of corresponding position of membrane and glass substrate show that line width errors is less than 1.3%, and the step depth errors is less than 8.6%. The diffraction efficiency in wavelength of 632.8 nm is 71.5%, which is 88% of theoretical value. It can be concluded that the membrane has light weighted structure, high replicated accuracy, and high diffraction efficiency, which meets the requirement of space-based telescope..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 920001 (2017)
Return loss of photonic bandgap fibers collimator
Li Yan, Zhao Yuan, Xu Xiaobin, and Cai Wei
A photonic bandgap fiber collimator was proposed. To reduce the interference of light power from the echo, the return loss of fiber collimator should exceed 60 dB. There was no reflection in photonic bandgap fiber end face, thus the beveled angle of GRIN lens of photonic bandgap fiber collimator and ordinary fiber collA photonic bandgap fiber collimator was proposed. To reduce the interference of light power from the echo, the return loss of fiber collimator should exceed 60 dB. There was no reflection in photonic bandgap fiber end face, thus the beveled angle of GRIN lens of photonic bandgap fiber collimator and ordinary fiber collimator satisfied the criterion were different. Based on the theory of matrix optics and Gaussian-beam coupling, the transform matrix was deduced from the general model of Gaussian-beam through a complex optical system. With the practical parameters of photonic bandgap fiber and GRIN lens, the influence of the distance between fiber tail and GRIN lens and the influence of the parameter of the GRIN lens on return-loss were both stimulated and analyzed. The results show that the return loss exceed 60 dB when the beveled angle of GRIN lens was 3°. The results may direct the design of PBF collimator..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 920002 (2017)
Tunable narrow bandwidth negative coefficient microwave photonic filter
He Chao, Liao Tongqing, Wu Sheng, and Wei Xiaolong
A tunable, narrow bandwidth, negative coefficient microwave photonic filter based on cascaded dispersion devices was proposed, because the negative coefficient microwave photonic filter was very difficult to realize by the way of positive coefficient optical taps. The reshaped output signals of the multi-wavelength fibA tunable, narrow bandwidth, negative coefficient microwave photonic filter based on cascaded dispersion devices was proposed, because the negative coefficient microwave photonic filter was very difficult to realize by the way of positive coefficient optical taps. The reshaped output signals of the multi-wavelength fiber laser were used as the tap of the filter. SMF and the F-P fiber ring were cascaded as a delay unit to realize the frequency selectivity of the filter. The negative coefficient was realized by a mixture of phase modulator and cascaded dispersion devices. As many as 37 stable laser signals with 0.34 nm wavelength interval were obtained by the experiment. And then based on the experiment results, the effects of coupling coefficient r of C2, C3 in the F-P fiber ring, different length TODL, and different length SMF in the delay unit etc. on the microwave photonic filters performance were simulated and studied..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 920003 (2017)
Kinetic process and tracking control of MOEMS scanning mirror under external parameter excitation
Wang Xiaoyi, Wang Qi, Li Yunxi, and Yang Yafei
With the development of MOEMS scanning mirror, the scanning mirror has profound applications in prospect on laser 3D image sensor by the advantages of high-speed resonance frequency and low cost for IC compatibility. It has significant theoretical and practical value to study the dynamic characteristic and control probWith the development of MOEMS scanning mirror, the scanning mirror has profound applications in prospect on laser 3D image sensor by the advantages of high-speed resonance frequency and low cost for IC compatibility. It has significant theoretical and practical value to study the dynamic characteristic and control problem of MOEMS scanning mirror under external parameter excitation. According to the Euler equation, the torsional dynamical model of electrostatic actuated MOEMS was built in this paper. It was suggested by the simulation through forth-order Runge-Kutta approach when the external parameter excitation was applied in the electrostatic actuated MOEMS reverse dynamical model, the MOEMS scanning mirror should experience the process of damped, periodic, period-doubling, forking, and chaos motion. Besides, the periodic motion had a large parametric control range. According to the stabilization theory by Lyapunov, a type of continuous tracking controller for chaotic system was designed to make the torsional states of the controlled MOEMS scanning mirror convergent to arbitrary expected command signal. It is shown by the experiment that the command signal of Lissajous pattern is suitable for laser 3D image sensor; the command signal of vector diagram is suitable for laser 3D printing system. Therefore, the theoretical analysis is consistent with the experiment..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 920004 (2017)
[in Chinese]
Dual-parameter sensing characterisitics of long period fiber grating cascaded with fiber MZ structure fabricated by CO2 laser
Liu Chao, Zhang Wen, Dong Mingli, Lou Xiaoping, and Zhu Lianqing
In order to achieve the temperature and strain of the two-parameter high-precision sensor measurements, a dual-parameter measurement of long period fiber grating(LPFG) fabricated by CO2 laser cascaded with fiber Mach-Zehnder (MZ) interference structure was proposed. The LPFG was fabricated using the CO2 laser and the fIn order to achieve the temperature and strain of the two-parameter high-precision sensor measurements, a dual-parameter measurement of long period fiber grating(LPFG) fabricated by CO2 laser cascaded with fiber Mach-Zehnder (MZ) interference structure was proposed. The LPFG was fabricated using the CO2 laser and the fiber MZ structure was fabricated using dislocation welding method. The sensing principle was derived and the transmission spectrum of the cascaded structure was monitored for temperature and strain measurements. The experimental results show that the LPFG is sensitive only to the temperature while the MZ structure is sensitive to both temperature and strain, when the temperature varied from 35 ℃ to 70 ℃, the LPFG sensitivities for warming and cooling are 38.57 pm/℃ and 39.17 pm/℃, respectively, while the MZ structure sensitivities are 38.57 pm/℃ and 37.50 pm/℃, respectively. When the strain varied from 0 με to 450 με, the MZ structure sensitivities for loading and unloading are 4.01 pm/με and 4.24 pm/με, respectively. A sensor with high sensitivity and good linearity for real-time and dynamic range measurements of dual-parameter was developed..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 922001 (2017)
Laser atmospheric channel estimation based on fast Bayesian matching pursuit
Ma Pengge, Chen Enqing, Pang Dongdong, and Yang Yi
Channel estimation refers to the method and process of receiving channel state information.The accuracy of channel estimation determines the performance of the receiver, so channel estimation must be carried out before equalization.Nowadays, the laser channel estimation for optics transmission becomes a key technology Channel estimation refers to the method and process of receiving channel state information.The accuracy of channel estimation determines the performance of the receiver, so channel estimation must be carried out before equalization.Nowadays, the laser channel estimation for optics transmission becomes a key technology in free space optical communication in multiple-input multiple-output orthogonal frequency division multiplexing(FSO-MIMO-OFDM) system. Although the traditional method of compression sensing, as an effective method for channel estimation, has the ability to recover and reconstruct the original signal, it has paid a certain cost in computational complexity. A novel fast Bayesian matching pursuit(FBMP) algorithm was proposed to overcome the low reconstruction precision and high complexity of the existing methods. Through the prior model selection and approximate minimum mean squared error(MMSE) estimation of the parameter vector, the FBMP algorithm provided an efficient way to estimate the channel impulse response and was characterized by high reconstruction accuracy and low complexity. Simulation results show that the proposed method can significantly improve the performance of the system compared with the traditional compressed sensing(CS)..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 922002 (2017)
Influence of decay factor and scale in the transverse on the three characteristics of Airy beam
Ke Xizheng, Song Qiangqiang, and Wang Jiao
Airy beam is a distinctive non-diffraction, which not only has properties of self -healing and non-diffraction, but also has the merit of self-bending that other non-diffraction beams do not have. The evolution of Airy beam′s non-diffraction, self-bending and self-healing was researched. The influence of different decaAiry beam is a distinctive non-diffraction, which not only has properties of self -healing and non-diffraction, but also has the merit of self-bending that other non-diffraction beams do not have. The evolution of Airy beam′s non-diffraction, self-bending and self-healing was researched. The influence of different decay factor a and scale in the transverse x0 on the three characteristics of Airy beam was discussed. The research shows that the non-diffracting propagation distance of Airy beam will decrease with the increase of decay factor a when the scale in the transverse x0 is constant, and the decay factor has no impact on self-bending. It also manifests that the recovery distance of self-bending will decrease with the increase of decay factor a. When the decay factor a is constant, the distance of non-diffracting transmission, the offset of the self-bending as well as the healing distance of self-healing increases in proportion to the scale in the transverse x0. By comparing the effects of scale in the transverse x0 and decay factor a on the three characteristics of Airy beam, it is found that the influence of decay factor a on the three properties of Airy beam is smaller than that of scale in the transverse x0..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 922003 (2017)
Open-loop Doppler frequency shift estimation in satellite coherent optical communication
Xu Yunxiang, Wu Bin, and Wang Bo
Satellite coherent optical communication has reached the engineering application stage at abroad, and the mostly used modulation and demodulation technique are BPSK/homodyne detection, in which OPLL is used for carrier recovery. Even nowadays, the application of OPLL is still difficult and the OPLL takes long time to cSatellite coherent optical communication has reached the engineering application stage at abroad, and the mostly used modulation and demodulation technique are BPSK/homodyne detection, in which OPLL is used for carrier recovery. Even nowadays, the application of OPLL is still difficult and the OPLL takes long time to capture the received signal. The open-loop conpensation algorithm based on DSP used in fiber communication was proposed to estimate the frequency and phase, and then was applied to the satellite laser communications. The effect of laser noise and receiver noise on frequency estimation precision was studied emphaisitly, and simulation was implemented to verify the algorithm. Results show that when the power of local oscillator (LO) is 10 dBm, the BER of the system is better than 10-4 with received power higher than -47 dBm; when the received power is increased by 10 dB, the standard deviation of the frequency estimation is less than 370 kHz..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 922004 (2017)
Hollow single-mode Bragg fiber for high power femtosecond pulse transmission
Li Yang, Liao Tongqing, Liu Daojun, Jing Baomi, Lv Xiaoguang, and Yan Yi
It is very difficult to transmit femtosecond pulses with high energy density in traditional optical fiber. So, a hollow single-mode Bragg fiber was designed. First, the cladding of hollow Bragg fiber was prepared based on one-dimensional photonic crystal′s bandgap characteristics. Then, the fiber structure parameters aIt is very difficult to transmit femtosecond pulses with high energy density in traditional optical fiber. So, a hollow single-mode Bragg fiber was designed. First, the cladding of hollow Bragg fiber was prepared based on one-dimensional photonic crystal′s bandgap characteristics. Then, the fiber structure parameters and transmission properties were analyzed by using the optical software FDTD Solutions. And then, the structure parameters were optimized to control dispersion curves through bringing in defect layer in cladding layer. It can be seen by full bandwidth scanning that the fundamental mode bandwidth achieve around 100 nm which can transmit 100 fs optical pulses..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 922005 (2017)
Research on optical channel of multiple LEDs lighting arrays distribution communication system in vehicle
Zhao Zixu, Song Xiaoqing, Jia Shengjie, Wei Youcai, and Wang Muyu
Due to the special vehicle′s narrow space, lighting layout is limited and the difficulty is increased. An optimal scheme of lighting layout was proposed based on optical power evenly distribution principle. Inter symbol interference model caused by the multipath dispersion from the reflection of floor in vehicle was buDue to the special vehicle′s narrow space, lighting layout is limited and the difficulty is increased. An optimal scheme of lighting layout was proposed based on optical power evenly distribution principle. Inter symbol interference model caused by the multipath dispersion from the reflection of floor in vehicle was built. The influence of multipath propagation delay on optical communication system was investigated. The relevant characteristic between the root mean square delay spread and max data rate was analyzed. Meanwhile, the Bit Error Rate(BER) was calculated by the simulation software. Simulation experiments proved that the optimizing layout scheme was valid as follows: the received optical power ranged from -0.73 dBm to 0.56 dBm in 2 m×2 m×1.5 m space size, uniform illumination rate was 80.5%, the average Signal Noise Ratio(SNR) was 20.92 dB. Moreover, the max data rate can be improved from 107.8 Mbps to 373.3 Mbps OOK at a BER of up to 1.47×10-6, which meet the international illumination standards and the actual data communication in a special vehicle..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 922006 (2017)
[in Chinese]
Resonance property of the surface plasmonic device of double stacked nanocone
Zhu Zhendong, Bai Benfeng, Tan Qiaofeng, Li Qunqing, Wang Xueshen, and Gao Sitian
Metallic nanostructures can enhance light-matter interaction arising from the surface plasmonic resonances, which is highlight on optics for many applications. A tunable optical property can be induced by plasmonic resonance, leading to the significant electromagnetic field enhancement, as well as the position of the &Metallic nanostructures can enhance light-matter interaction arising from the surface plasmonic resonances, which is highlight on optics for many applications. A tunable optical property can be induced by plasmonic resonance, leading to the significant electromagnetic field enhancement, as well as the position of the "hot spot" at a tiny nanogap. Analogue of the diffractive optics, an alternative method of multiscale cascaded field enhancement with a simple metallic nanostructure, double stacked nanocone (DSC), was proposed in the article. In detail, a tunable hybrid mode was achieved from the strong interference between a fundamental plasmonic cavity mode and a plasmonic gap mode. Furthermore, it led to a far-field optical response at a certain wavelength. The position of the hot spots can also be mounted on the top surface of the DSC nanostructure. Additionally, a technique of mask reconfiguration was developed to precisely fabricate the multiscale DSC nanostructure, which can benefit to construct the necessary three steps in the nanostructure. The experimental results also provide a substantial evidence to demonstrate the art-of-state of the multiscale cascaded field enhancement, as well as the technique of nanofabrication..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 934001 (2017)
[in Chinese]
Analysis of LOS pointing and rate compensation for two-axis FSM
Du Yanlu, Ding Yalin, Xu Yongsen, and Li Jun
In order to control line-of-sight(LOS) pointing with two-axis fast-steering mirror(FSM) accurately, kinematic equations was set to describe the relationship between LOS pointing and angular displacement of FSM deriving from Snell′s law of reflection. LOS pointing equations were decoupled with non-linear correction. LOSIn order to control line-of-sight(LOS) pointing with two-axis fast-steering mirror(FSM) accurately, kinematic equations was set to describe the relationship between LOS pointing and angular displacement of FSM deriving from Snell′s law of reflection. LOS pointing equations were decoupled with non-linear correction. LOS pointing error was less than 8 ?滋rad for two-axis FSM whose tilt angles were both ±20 mrad with beam incidence angle equaling to 45°. LOS pointing accuracy rose 75 times compared with linear approximation. To hold the LOS stationary, rate equations were established in terms of vector rate synthesis to compensate the angular rate of the mounted vehicle in inertial space. Angular rate equations for FSM were simplified via Taylor expansion and high order truncation. The residual angular rate of LOS with different beam incidence angles was calculated, which indicated that the residual error of ?棕Ly was far greater than ?棕Lz. The ratio between residual LOS angular rate and angular rate of mounted vehicle was minimal and less than 0.164% when beam incidence angle was 45°, which satisfied the accuracy requirements. The equations deduced suppliy theoretic reference of position and velocity command generation for FSM control system..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 918001 (2017)
Design of infrared dual band optical system based on anti-laser detection
Chen Yang, Zhang Anfeng, and Ru Zhibing
Aiming at the threat of laser active detection technology to electro-optical devices, a method using photosensitive surface inclined design to reduce the laser echo energy was proposed, so as to improve the system performance of anti-laser detection. A middle and long wave dual band infrared anti-laser detection opticaAiming at the threat of laser active detection technology to electro-optical devices, a method using photosensitive surface inclined design to reduce the laser echo energy was proposed, so as to improve the system performance of anti-laser detection. A middle and long wave dual band infrared anti-laser detection optical system was designed whose photosensitive surface inclined 5°. The aberration of the photosensitive surface was corrected by using the free-form surface. The designed system operating band was 3-5 μm, 8-12 μm. The field angle was ±2.4°, the number of F was 2. This result shows that the transmission function of the two bands is higher than 0.38 at the frequency of 17 lp/mm of Nyquist, which satisfies the requirement of imaging quality of infrared system. Then, through the anti-chase track analysis, the detection distance of the system is effectively reduced..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 918002 (2017)
Assembly for large aperture telescope primary mirror support system
Zhao Yongzhi, Shao Liang, Ming Ming, Lv Tianyu, and Liu Changhua
According to 1.2 m large aperture telescope primary mirror support system, an effective assembly method was advanced to insure the root-mean-square (RMS) of the surface accuracy. The primary mirror support system was designed following kinematic principle. To achieve excellent performance of the RMS of primary mirror sAccording to 1.2 m large aperture telescope primary mirror support system, an effective assembly method was advanced to insure the root-mean-square (RMS) of the surface accuracy. The primary mirror support system was designed following kinematic principle. To achieve excellent performance of the RMS of primary mirror surface accuracy at different ambient temperature (from -20 ℃ to 60 ℃) and different elevation(from vertical to horizontal), whiffletree structure were used for axial support,while lateral support mechanisms based on flexible tangent link structure were adopted. Resulting from machining error and installation error of the flexible structures, assembly stress was presented certainly, that could increase primary mirror distortion range evidently. By the finite element analysis(FEA) simulation, the effects of various errors were calculated. According to simulation results, assembly processes were established. After assembly of primary mirror support system, the RMS of primary mirror surface accuracy was measured by compensator and laser interferometer. In measurement, the RMS of surface accuracy was λ/42 and λ/31(λ=632.8 nm), when optical axis of primary mirror was vertical and horizontal..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 918003 (2017)
[in Chinese]
Experimental study on aero-optical transmission effect of infrared window in aerothermal environment
Ma Haojun, Wang Guolin, Chen Dejiang, Zhang Jun, Liu Liping, and Luo Jie
Aero-optical effect caused by infrared window in aerothermal environment has a serious effect on infrared imaging detector of high-speed missile. Experimental study on this effect which was carried through in plasma wind tunnel was represented in the paper. The surface temperature and heat flux of infrared window were Aero-optical effect caused by infrared window in aerothermal environment has a serious effect on infrared imaging detector of high-speed missile. Experimental study on this effect which was carried through in plasma wind tunnel was represented in the paper. The surface temperature and heat flux of infrared window were measured in the experiment. Wavefront phase of light through the infrared window was measured with a radial shearing interferometer. The changes of point spread function and Strehl ratio with duration of heat were obtained. It is validated that infrared windows result in intensity attention and energy distribution disperse for light beam in far-field..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 904001 (2017)
Jamming effectiveness simulation of surface source infrared decoy in air confrontation
Li Taorui, Tong Zhongxiang, Huang Hesong, Wang Chaozhe, and Li Shenbo
Compared with traditional infrared decoy, surface source infrared decoy has obvious superiority in burning rate, diffusion range, jamming effectiveness and so on. Considering the economy of cost and improvement of jamming effectiveness testing efficiency, a thought which can simulate the testing work was proposed basedCompared with traditional infrared decoy, surface source infrared decoy has obvious superiority in burning rate, diffusion range, jamming effectiveness and so on. Considering the economy of cost and improvement of jamming effectiveness testing efficiency, a thought which can simulate the testing work was proposed based on air confrontation. Firstly, the models of missile movement, seeker tracking and aircraft infrared radiation were established, which were regarded as hypothesis of air confrontation both sides. Secondly, the motion and burning model of decoy foil was built. The decoy foil was taken as the researching object and solving foil surface temperature distribution. By optimizing combustion algorithm, the overall radiation characteristic was obtained. Finally, through changing factors, such as the launch angle, height of decoy and the speed of aircraft, jamming effectiveness was tested. It′s resulted from simulation that the effectiveness evaluation thought close to the real scene is feasible and effective, meeting the demand of evaluation..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 904002 (2017)
Phase spectra extract of thermal wave with wavelet decomposition and coating thickness estimation
Guo Wei, Dong Lihong, Wang Haidou, Xu Yawei, and Xu Binshi
Aiming at the thickness estimating problem of thermal barrier coatings during preparation, the transient thermal response spectrum of NiCrAlY coating on nickel-based superalloy was researched through numerical simulation method. Further more, the phase spectra of original thermal waves with different coating thickness Aiming at the thickness estimating problem of thermal barrier coatings during preparation, the transient thermal response spectrum of NiCrAlY coating on nickel-based superalloy was researched through numerical simulation method. Further more, the phase spectra of original thermal waves with different coating thickness was analysed, which suggested that the phase value and coating thickness comply with linear relationship in a special range of frequency. But the absolute phase D-value is too little to evaluate coating thickness in engineering application. So a method of wavelet decomposition was proposed to increase the phase D-value between different coating thickness, the 2nd level details coefficient was employed for thermal wave reconstruction, and the phase D-value of reconstructed thermal wave increase about more than 500 times, which is extremely conducive to raise the accuracy rate in coating thickness estimation. At last, the analog result was confirmed by experimental test..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 904003 (2017)
Reasonable benefit value of the parameters of the parallel infrared binocular stereo system
Wang Tonghao, Liu Bingqi, Huang Fuyu, Chen Yichao, and Zhang Shuai
In order to solve the shortcomings of the nighttime auxiliary driving plane display and obtain rich 3D layering under reasonable benefit, based on the parallel infrared binocular night vision system, the minimum resolution distance of the infrared binocular system and the human eye stereoscopic perception was analyzed.In order to solve the shortcomings of the nighttime auxiliary driving plane display and obtain rich 3D layering under reasonable benefit, based on the parallel infrared binocular night vision system, the minimum resolution distance of the infrared binocular system and the human eye stereoscopic perception was analyzed. Combined with the mechanism of stereo-perception of the human eye and the condition of viewing the 3D image with large angle of view and rich 3D layering from the image hierarchy, the parameters of the infrared binocular stereo system were deduced. Finally, according to the results of the derivation, the reasonable benefit of the horizontal pixels corresponding to three different specifications display was calculated and analyzed, and five sets of infrared images with different horizontal pixels were selected for experimental verification. The results show that the infrared night vision system based on the results of the derivation not only allows the observer to obtain a larger field of view, but also takes effect..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 904004 (2017)
Design of control system for fast steering mirror of infrared detector based on satellite
Lv Shiliang, Liu Jinguo, Zhou Huaide, and Mei Gui
Imaging motion compensation is one of the key technologies to improve the imaging quality in infrared detector based on the satellite. The control system of the fast steering mirrors was proposed to compensate the imaging motion respectively in the pitching direction and azimuth direction, considering the optical systeImaging motion compensation is one of the key technologies to improve the imaging quality in infrared detector based on the satellite. The control system of the fast steering mirrors was proposed to compensate the imaging motion respectively in the pitching direction and azimuth direction, considering the optical system and the working mode for the infrared detector based on the satellite. Firstly, the principle of infrared remote sensing and imaging motion were introduced. Secondly, the design features and components of optical system of the infrared detector were analyzed in detail. Thirdly, the causes of imaging motion in the infrared detector on orbit was analyzed, and the imaging motion value both in the pitching direction and azimuth direction was calculated according to the optical system and imaging working mode. Finally, the scheme of image motion compensation was proposed and the hardware system was designed in detail. The calculated result shows that the range of movement and acceleration of the image motion compensation can meet the precision requirements for infrared detector..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 904005 (2017)
[in Chinese]
Numerical simulation of actively Q-switched intracavity sum-frequency Raman laser
Yu Xueli, Ding Shuanghong, Jia Haixu, and Xin Lei
The normalized rate equations of the LD pumped actively Q-switched intracavity sum-frequency Raman laser were deduced, and the reasonable value scope of seven comprehensive factors of the rate equations was estimated respectively according to the parameters of typical experimental setups. The influences of the compreheThe normalized rate equations of the LD pumped actively Q-switched intracavity sum-frequency Raman laser were deduced, and the reasonable value scope of seven comprehensive factors of the rate equations was estimated respectively according to the parameters of typical experimental setups. The influences of the comprehensive factors on the laser output peak power, single pulse energy and pulse width were researched by the numerical simulation of the actively Q-switched intracavity sum-frequency Raman laser. It was found that there was a matching relation between the normalized sum-frequency factor F and the normalized Raman gain coefficient M, and the matching equations and curves of F and M at different inversion population density N were obtained by making use of the method of numerical fitting, the result demonstrates that the matching values of F and M are basically linearly related, which can be employed to guide the optimization of parameters of the length of Raman medium and sum-frequency crystal in the experiment to accomplish the high efficient sum-frequency laser. Finally, the results are used to calculate and analyze the reported experiment to optimize the parameters of setups to gain higher output power and more efficient laser..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 906001 (2017)
Tunable dual-wavelength external cavity semiconductor laser
Bai Huijun, Wang Yuefeng, Wang Junzhen, and Guo Tianhua
A double grating external cavity semiconductor laser based on a volume Bragg grating (VBG) and a transversely chirped volume Bragg grating (TCVBG) were reported. The external cavity semiconductor laser consisted of a VBG with the reflectivity of 15% and a TCVBG with the reflectivity of 17%, which function as feedback eA double grating external cavity semiconductor laser based on a volume Bragg grating (VBG) and a transversely chirped volume Bragg grating (TCVBG) were reported. The external cavity semiconductor laser consisted of a VBG with the reflectivity of 15% and a TCVBG with the reflectivity of 17%, which function as feedback element and mode selection element to achieve specific wavelength selection and wavelength tuning. The power, spectral and wavelength tuning characteristics of external cavity laser semiconductor using VBG and TCVBG were demonstrated. The experimental results indicate that an output power of 1.96 W is obtained with the slop efficiency of 0.94 W/A, which corresponds to the efficiency of 78% compared to the output power in free-running LD. A dual-wavelength was achieved with the linewidth down to 0.3 nm, and one wavelength of 808.6 nm was stabilized, and by adjusting the position of the chirped volume Bragg grating in the transverse direction, another wavelength was tuned in a 15 nm wavelength tunable range from 800 nm to 815 nm..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 906002 (2017)
Effect of laser shock processing on microstructure and properties of K403 alloy repaired by laser cladding
Zhang Peiyu, Wang Cheng, Xie Mengyun, Li Yuqin, and An Zhibin
Aiming at bulky grains and declination of mechanical properties of K403 nickel-alloy repaired by laser cladding, the laser shock processing(LSP) technology was applied to strengthen the surface of repaired region. The microstructuree was observed through SEM and the mechanical properties were represented by testing micAiming at bulky grains and declination of mechanical properties of K403 nickel-alloy repaired by laser cladding, the laser shock processing(LSP) technology was applied to strengthen the surface of repaired region. The microstructuree was observed through SEM and the mechanical properties were represented by testing microhardness, residual stress and high temperature tensile strength. The results show that the LSP refines crystalline grain of the surface of the specimen. After LSP, the surface hardness of matrix region and cladding zone were improved by 21% and 8% respectively. The hardness affected depth of the LSP was about 0.8 mm. Besides, about 610 MPa and equally distributed residual compressed stress was generated and the affected depth was about 1.2 mm. After thermal retardation, the residual compressed stress was released by about 18%, but high residual compressed stress also existed on surface. The high temperature tensile strength was increased by about 15% after LSP. The problem of mechanical properties decrease of K403 nickel-alloy repaired by laser cladding was solved..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 906003 (2017)
Arctangent compensation algorithm of laser speech detection system
Yan Chunhui, Wang Tingfeng, Zhang Heyong, Lv Tao, and Zhao Yanming
The arctangent demodulation compensation algorithm with parameter estimation error was proposed through analyzing laser speech detection system in theory, then quantitative mathematical formulas between the total harmonic distortion(THD) and key parameters as well as errors were built up. The THD and spurious free dynaThe arctangent demodulation compensation algorithm with parameter estimation error was proposed through analyzing laser speech detection system in theory, then quantitative mathematical formulas between the total harmonic distortion(THD) and key parameters as well as errors were built up. The THD and spurious free dynamic range(SFDR) were considered in this paper, which indicated the demodulation effect of micro vibration signal and minimum signal value distinguished from a large disturbance signal (jamming signal), respectively. This system implemented non-contact, long distance and high sensitive acoustic micro vibration signal detection. Laboratory experiments and simulations were presented to verify the feasibility of the arctangent demodulation compensation algorithm. Results illustrate that this system can detect the micro vibration caused by sound wave and recover voice signal from received signal within 35 meters using the compensation algorithm based on optical hardware platform currently..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 906004 (2017)
Numerical simulation of laser propagation effects through subsonic hemispherical/cylindrical wake
Guan Qi, Du Taijiao, Chen Zhihua, Yan Wei, and Peng Guoliang
Compressible large eddy simulation was carried out to study the flow field around a hemispherical/cylindrical structure at Mach number of Ma=0.4. Optical path difference and aero-optical phase were calculated according to density data obtained by the large eddy simulation method, and then the aero-optical effect of theCompressible large eddy simulation was carried out to study the flow field around a hemispherical/cylindrical structure at Mach number of Ma=0.4. Optical path difference and aero-optical phase were calculated according to density data obtained by the large eddy simulation method, and then the aero-optical effect of the wake was studied. The results show that the time-averaged root-mean-square of optical path difference increases with the angle of projection, and it varies from 0.11 μm to 0.28 μm when the angle of projection increases from 120°to 148°. Besides, the root-mean-square of optical path difference changes dramatically over time, and its temporal root-mean-square value reaches 0.04 μm when the angle of projection is 148°. The wake of the hemispherical/cylindrical structure has great effect on laser propagation, and the time-averaged Strehl ratio is 0.33 for the angle of projection of 148°. The time-averaged Strehl ratio decreases with the angle of projection, and it reduces 59% when angle of projection increases from 120°to 148°. The Strehl ratio also changes dramatically over time, and its temporal root-mean-square value is 0.05..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 906005 (2017)
Effect of electromagnetic stirring on melt flow velocity of laser melt pool and solidification structure
Yang Guang, Zhao Endi, Qin Lanyun, Li Changfu, and Wang Wei
In order to study the effect of electromagnetic stirring on laser melt pool solidification of TA15 titanium alloy, A MHD mathematical model was established on minimal melt pool under the three-phase three-pole rotating electromagnetic stirrer. This model was used to calculate magnetic induction intensity in the center In order to study the effect of electromagnetic stirring on laser melt pool solidification of TA15 titanium alloy, A MHD mathematical model was established on minimal melt pool under the three-phase three-pole rotating electromagnetic stirrer. This model was used to calculate magnetic induction intensity in the center of magnetic field and the melt circumferential flow velocity in melt pool under different exciting current. The influence of circumferential flow velocity on temperature field and solidification structure formation were analyzed. At last the analysis results were verified by experiment method. The results showed that the electromagnetic force drived melt to flow circumferentially. Farer from the magnetic field center, lorentz force was larger which promoted the circumferential flow velocity of melt. Magnetic induction intensity was rising with the increase of exciting current, which caused more faster circumferential flow velocity. The enhance of flow velocity resulted in temperature going down in melt pool and temperature gradient on solid-liquid interface, which were good for generation of the equiaxed crystal. The experiment results testified that equiaxed grains were generated at the top of melt layer with the magnetic field. The number of the equiaxed grains were rising with an increase of the distance from magnetic field center. The tendency of analysis results are in good agreement with the experimental results..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 906006 (2017)
Laser cladding forming of fan-shaped part based on hollow laser beam inside powder feeding technology
Zhou Bin, Shi Shihong, Deng Zhiqiang, Shi Tuo, Fu Geyan, and Fang Qinqin
Based on hollow laser beam inside powder feeding technology, the study of forming fan-shaped part whose cladding height was unequal was carried out by the method of variable attitude forming and normal lamination method. The connection between cladding height and scanning velocity was analyzed. The cladding with unequaBased on hollow laser beam inside powder feeding technology, the study of forming fan-shaped part whose cladding height was unequal was carried out by the method of variable attitude forming and normal lamination method. The connection between cladding height and scanning velocity was analyzed. The cladding with unequal height was formed by the method of piecewise variable velocity combining geometric model and the connection above. Based on this method, the fan-shaped part was formed. The experimental result indicates that the formed part has high-precision dimension and good surface quality. In addition, the microstructures of the part at different parameter have no significant differences, and all achieve small grain size and compact texture..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 906007 (2017)
Design of miniaturized transmitting-receiving system for laser detection
Han Wei, Zheng Xiang, and Zhao Baiqin
Aiming at the design difficulty of miniaturized laser transmitting-receiving detection system, a solution for large field of view, miniaturization was proposed. Laser chip and driving circuit were integrated on aluminum nitride substrate, which achieved the purpose of improving performance and dimension compression. AcAiming at the design difficulty of miniaturized laser transmitting-receiving detection system, a solution for large field of view, miniaturization was proposed. Laser chip and driving circuit were integrated on aluminum nitride substrate, which achieved the purpose of improving performance and dimension compression. According to theoretical calculation and ZEMAX optical simulation, the optical fiber, free surface array cylindrical lens and spherical cylindrical lens were used to realize shaping and convergence of light, which reduced the axial dimension. A small size receiving module with amplified circuit was designed. The electromagnetic interference caused by the pulse current was analyzed in the miniaturized system, further more, a variety of electromagnetic compatibility measures were adopted to shield electromagnetic interference. At last, the initial prototype was made and the experiment of measurement was done. Results show that the system can effectively suppress the electromagnetic interference, and detect the target at the distance of 5 m. Therefore, it verifies the feasibility of the miniaturization technology..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 906008 (2017)
Design of high speed Q-switch drive circuit based on Marx generator
Feng Wen, Yan Fanjiang, Zhao Liangbo, Yang Chao, and Li Xu
Aiming at the characteristics of high speed for Q-switch, a novel design method of high speed Q-switch drive circuit based on Marx generator was proposed. The high pressure module was used to generate high voltage to charge the capacitors in parallel, and the transformer was used to drive 8 MOS transistors. When the trAiming at the characteristics of high speed for Q-switch, a novel design method of high speed Q-switch drive circuit based on Marx generator was proposed. The high pressure module was used to generate high voltage to charge the capacitors in parallel, and the transformer was used to drive 8 MOS transistors. When the trigger signal arrived, meanwhile the capacitors discharge in series as the MOS transistors were in ON-state, so that a higher voltage pulse can be obtained as the voltage multiplier. Experiment results show that the rise time of Q-switch pulse is about 12 ns, voltage magnitude is 3 000-4 000 V. Compared to the wave of traditional pulse transformer, the rise time minish 35 ns.The Q-switched module has already been used in the laser diode (LD) pumped solid Nd: YAG laser, and it works steadily and chronically..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 906009 (2017)
[in Chinese]
Visual tracking algorithm based on deformable parts model
Ma Junkai, Luo Haibo, Chang Zheng, Hui Bin, Zhou Xiaodan, and Hou Defei
In recent years, the technology of target tracking has been greatly developed, but occlusion and deformation of the target were still the major challenges in tracking algorithms. To address these problems, a tracking algorithm based on deformable parts model (DPM) was proposed. Firstly, DPM was used to represent the taIn recent years, the technology of target tracking has been greatly developed, but occlusion and deformation of the target were still the major challenges in tracking algorithms. To address these problems, a tracking algorithm based on deformable parts model (DPM) was proposed. Firstly, DPM was used to represent the target object. DPM divided the target into several small parts. The feature of the target was composed of the local feature of each part and the global feature of the entire object, then DPM defined a uniform similar function based on the object feature and spatial relationship of each pair of parts. Secondly, a structured output support vector machine (structured SVM) was trained online as the classifier, the output of the structured SVM was the structured description of the object. The target in videos or image sequences could be tracked by the detection result of the classifier. Experimental results demonstrate that the proposed methods outperform other popular trackers, especially with the challenge of object′s occlusion and deformation..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 928001 (2017)
[in Chinese]
Scanning measuring system of stray light for optical remote sensing satellite
Li Junlin, Zhang Liming, Si Xiaolong, Huang Wenxin, Du Zhiqiang, Xu Weiwei, Wang Jixiang, Xu Yongping, Yang Baoyun, Zhu Xuemei, Wang Shaolin, Ma Wenjia, Yang Chunyan, and Li Yang
For measuring the stray light level and verifying the ability of stray light suppression of optical remote satellite, the imaging time and orbital characteristic of some satellite were analyed, a scanning system of stray light measuring for optical remote satellite was developed, which was based on a large 7-dimension For measuring the stray light level and verifying the ability of stray light suppression of optical remote satellite, the imaging time and orbital characteristic of some satellite were analyed, a scanning system of stray light measuring for optical remote satellite was developed, which was based on a large 7-dimension robot. According to the annual lighting condition of satellite in orbit, the controlling formulae were deduced for all the kinematic mechanism, with the scanning azimuth angle -90°-+90°, pitch angle -29°-+42.5°, and their angular accuracy were up to 0.2° and 0.1° separately, the position accuracy was better than 10 mm. Otherwise, an extinction subsystem, which was made was low reflectance material(lower than 1.5% between 400-1 600 nm) and large extinction structure and extinction coefficient could reach 9.9×10-7, was used to simulate extreme dark target and deep space room. The scanning system of stray light measuring for optical remote satellite can satisfy most optical payload at present for stray light measurement, analysis and verification..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 913001 (2017)
A weak signal detection technique applied in deep space exploration
Lin Xuling, Wu Zhiqiang, Yang Song, Zhang Zhi, Bi Siwen, Zhang Xuan, and Du Yujie
Deep space exploration has great significance for human being to develop and utilize space resources. Remote sensing payload is a very important part of deep exploration. Since the detection distance in the deep space exploration mission is very far, the SNR of the received signals is very low, the capture of extremelyDeep space exploration has great significance for human being to develop and utilize space resources. Remote sensing payload is a very important part of deep exploration. Since the detection distance in the deep space exploration mission is very far, the SNR of the received signals is very low, the capture of extremely weak signals from deep space is a key technology. Based on the requirement of future deep space exploration for ultra weak signal detection, a week signal detection method was given. The method was based on quantum squeezed states, whose shot-noise was less than the standard quantum limit, and some experimental results were given. The result shows that this technique was a promising technology in future deep space exploration. Because the quantum properties of squeezed light is attenuated as the distance increases, in order to be closer to the application, a new laser radar scheme was designed which injected squeezed light at the receiving end, and simulation results were given..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 913002 (2017)
[in Chinese]
Modulated multi-wavelength correlated imaging system with DMD
Ma Jingting, Liu Zunlong, Wang Minhang, Feng Fei, Xu Jiangmeng, and Zhang Weijie
Correlated imaging is a new imaging method, which attracts a lot of attention in recent years. It offers great potential to solve some problems that traditional imaging technologies cannot solve. Among them, computational correlated imaging based on digital micromirror device(DMD) or spatial light modulator(SLM) develoCorrelated imaging is a new imaging method, which attracts a lot of attention in recent years. It offers great potential to solve some problems that traditional imaging technologies cannot solve. Among them, computational correlated imaging based on digital micromirror device(DMD) or spatial light modulator(SLM) developed most rapidly. When DMD was applied in correlated imaging system, high-quality images can be obtained at multi-wavelength, and multi-wavelength correlated imaging was redlized, by using the advantages of DMD′s high speed and wide reflective spectrum, with the assistance of compressed sensing. Several problems in the system need to be researched on, including the efficient generation of pseudo thermal light, the influence of diffraction effect and modulation noise on the signal, and the high-quality imaging reconstruction algorithm. After determining the optimal system parameters via numerical simulation, an experimental system was built to verify the effectiveness of the technology, which provide an reference to the practical process of correlated imaging..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 924001 (2017)
[in Chinese]
Multilayer-DLC film with low inner-stress prepared by pulsed laser deposition
Lu Yimin, Guo Yanlong, Huang Guojun, Li Wei, Wan Qiang, and Tang Huang
Multilayers diamond-like carbon film, which was composed of several thick diamond-like carbon layers and thin germanium island layers, was prepared on the germanium substrate in order to resolve the high inner-stress in the diamond-like carbon film. The diamond-like carbon layers had the main function of protection, anMultilayers diamond-like carbon film, which was composed of several thick diamond-like carbon layers and thin germanium island layers, was prepared on the germanium substrate in order to resolve the high inner-stress in the diamond-like carbon film. The diamond-like carbon layers had the main function of protection, and the germanium island layers had the buffer function to reduce the inner-stress in the diamond-like carbon film. Meanwhile, the thicknesses of the germanium layers were very thin, so they had no influence on the mechanical and infrared performances of the whole film nearly. Inner-stress in the multilayers diamond-like carbon film was 2.14 GPa, 39% lower than that of the pure diamond-like carbon film, and the multilayers diamond-like carbon film could pass the friction test stipulated in the GJB2485-95′general specification for optical coatings. The hardness of the multilayers diamond-like carbon kept high hardness of 47 GPa, and had the same surface roughness to the pure diamond-like carbon film. Therefore, the multilayers diamond-like carbon film could be used as practical protective film for infrared window..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 921001 (2017)
Broadband terahertz quarter wave plate based on meander-line dielectric metamaterials
Ge Dongsen, Xu Quan, Wei Minggui, Zhang Xueqian, and Han Jiaguang
In this work, a broadband terahertz quarter wave plate was designed using high-resistance silicon based on meander-line dielectric metamaterials, which could convert the terahertz linear-polarization incidence to circular-polarization output. The 3D full-wave simulation shows that the birefringence property of the struIn this work, a broadband terahertz quarter wave plate was designed using high-resistance silicon based on meander-line dielectric metamaterials, which could convert the terahertz linear-polarization incidence to circular-polarization output. The 3D full-wave simulation shows that the birefringence property of the structure can be freely adjusted by properly designing the geometric parameters, which allows to engineer the transmission amplitudes of two orthogonal terahertz linear polarizations to be close to each other(about 0.55), while the phase difference to be 90°. Based on the design, a terahertz quarter wave plate was fabricated using ion-beam etching method, and then experimentally characterized using terahertz time-domain spectroscopy system. The experimental results agree well with the simulations, which indicates that a broadband terahertz quarter wave plate that functions at 1.07-1.41 THz with a high normalized ellipticity over 0.99 was realized, demonstrating the validity of our designing scheme very well. Besides, by changing the geometrical parameters of the structure, two different broadband terahertz quarter wave plates that function at other frequency ranges were further designed, which confirms the tunability of the proposed structure..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 921002 (2017)
Physical model of optical constants of SiO2 thin films
Liu Huasong, Yang Xiao, Liu Dandan, Wang Lishuan, Jiang Chenghui, Jiang Yugang, Ji Yiqin, Zhang Feng, and Chen Deying
SiO2 thin films were deposited by ion beam sputtering (IBS) and electron beam evaporation (EB) technologies. The optical constants of SiO2 thin films were fitted by nonlinear least square algorithm. 8 group experiments were designed based on L8(22) orthogonal array. The results show that intermix is the most important SiO2 thin films were deposited by ion beam sputtering (IBS) and electron beam evaporation (EB) technologies. The optical constants of SiO2 thin films were fitted by nonlinear least square algorithm. 8 group experiments were designed based on L8(22) orthogonal array. The results show that intermix is the most important factor for the IBS SiO2 thin film while Proe model for the EB SiO2 thin film. The values of MSE evaluation function for IBS SiO2 thin film and EB SiO2 thin film decline 35% and 38% respectively, which shows that the physical models are reasonable and the physical meaning is clear. The method to estimate the effect of different factors was offered, which is meaningful for the analysis of optical constants of thin films..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 921003 (2017)
[in Chinese]
Active disturbance rejection controller of opto-electronic platform based on precision model identification
Yin Zongdi, Dong Hao, Shi Wenjie, and Zhang Feng
PID controller is widely used in most projects, but its weakness is more and more fatal with the development of the stabilization precision. An active disturbance rejection controller (ADRC) based on system identification was proposed to control complex opto-electronic platform which can be described by exact model. FiPID controller is widely used in most projects, but its weakness is more and more fatal with the development of the stabilization precision. An active disturbance rejection controller (ADRC) based on system identification was proposed to control complex opto-electronic platform which can be described by exact model. Firstly, the system model joined friction and structure resonance models were established in order to simulate full practical states in Matlab. Secondly, the rank of system was confirmed by AIC and the model of system was confirmed by linear least square method, and then the model was transformed into the first visible standard type. Finally, an active disturbance rejection controller was designed. The weakness of PID was conquered by 4th Tracking-Differentiator (TD), 5th Extended State Observer (ESO) and Nonlinear States Error Feedback (NLSEF). Take some complex opto-electronic platform as an example, a series of simulated contrast tests between ADRC and PID were carried out. The results showed that the overshoot was reduced from 1.8% to 0.9%,and the maximum tracking error was reduced from 0.03(°) /s to 0.013(°)/s. ADRC had a faster response with a smaller overshoot than PID. This indicates that ADRC achieve control more accurately than PID..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 926001 (2017)
Distributed asynchronous sequential fusion algorithm for multiple optic-electronic tracking devices
Chu Tianpeng
An asynchronous distributed sequential fusion algorithm was proposed for the asynchronous measurements which were measured by the networked optic-electronic tracking devices. The asynchronous distributed sequential fusion algorithm was composed of a local estimator and a fusion estimator. First, by using the state tranAn asynchronous distributed sequential fusion algorithm was proposed for the asynchronous measurements which were measured by the networked optic-electronic tracking devices. The asynchronous distributed sequential fusion algorithm was composed of a local estimator and a fusion estimator. First, by using the state transformation method, the asynchronous measurements obtained by a sensor node was aligned to the fusion instant to get the pseudo-measurements. Then, a local sequential estimator was developed with respect to the pseudo-measurements and the target motion model to calculate the local estimation, by using orthogonal projection. Subsequently, by modifying the covariance intersection algorithm, a diffusion-based fusion estimator was designed to fuse the local estimation in the neighborhood. The simulation results of a target tracking system validate the effectiveness of the proposed target tracking algorithm..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 46, Issue 9, 926002 (2017)
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