Journals >Infrared and Laser Engineering
Contents
2015
Volume: 44 Issue 6
49 Article(s)
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[in Chinese]
Content measurement of hydrocarbons in alkylate gasoline based on terahertz time-domain spectroscopy
Bao Rima, Dong Chen, Lan Xingying, Feng Chengjing, Meng Qian, and Zhao Kun
In this work, terahertz time-domain spectroscopy(THz-TDS) was used to measure the content of hydrocarbons in alkylate gasoline as a new kind of non-destructive testing. 2,4,4-trimethyl-pentene(2,4,4-TMP), a representative kind of olefin, was mixed in alkylate gasoline. The spectral response of the samples containing diIn this work, terahertz time-domain spectroscopy(THz-TDS) was used to measure the content of hydrocarbons in alkylate gasoline as a new kind of non-destructive testing. 2,4,4-trimethyl-pentene(2,4,4-TMP), a representative kind of olefin, was mixed in alkylate gasoline. The spectral response of the samples containing different 2,4,4-TMP in terahertz band was analyzed. The results showed that amplitude of samples had a significant change in signals and varied linearly with content of 2,4,4-TMP changed. The curves, fitting by maximum and minimum values(amplitude) of spectra, were used to predict two unknown sample concentration. As a result, the error is less than 0.5%. Meanwhile, the absorption coefficient of samples were analyzed. The research indicates that THz -TDS technique is very suitable for detection of composition and content of hydrocarbons in gasoline..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1823 (2015)
Error analysis of quartz glass terahertz optical parameter measurement
Yang Xiaojie, Li Xiangjun, and Liu Jianjun
When the THz optical parameters of gas or liquid samples in quartz glass container were measured in the most cases, the influence of THz optical parameters quartz glass should be considered. The time domain spectroscopy of quartz glass was measured, then it′s the refractive index and absorption coefficient in THz band When the THz optical parameters of gas or liquid samples in quartz glass container were measured in the most cases, the influence of THz optical parameters quartz glass should be considered. The time domain spectroscopy of quartz glass was measured, then it′s the refractive index and absorption coefficient in THz band were calculated by the analytical formula. At last the error of its optical parameters was analyzed by the theory of error propagation. It is found that the error of the refractive index is almost invariable in 0.2-2.0 THz, and the error of the absorption coefficient is exponentially increasing with frequency increasing. The result is significant for improving the accuracy of THz optical parameters of gas or liquid samples in quartz glass container..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1827 (2015)
Influence of temperature on resonant properties in terahertz subwavelength metal structures
Wu A′ni, Li Chenyu, Zhou Qingli, Liu Jianfeng, Sun Huijuan, Yang Zhou, and Zhang Cunlin
By using terahertz time domain spectroscopy(THz-TDS), the transmission and resonance properties of terahertz subwavelength metal structures at different temperatures were studied. The transmission of "U"- and "E"-shaped structures decreased gradually with temperature increasing from 80 K to 380 K. MBy using terahertz time domain spectroscopy(THz-TDS), the transmission and resonance properties of terahertz subwavelength metal structures at different temperatures were studied. The transmission of "U"- and "E"-shaped structures decreased gradually with temperature increasing from 80 K to 380 K. Meanwhile, the low resonance frequency showed a slight red-shift. Through the study of temperature-dependent transmission spectra at resonance and non-resonance regions, the phenomenon of transmission decreasing was attributed to the increasing of carrier concentration in GaAs substrate. The weakened resonant strength originated from the resonate quench by temperature-generated carriers in substrate. The red-shift was due to the increase of refractive index. The investigation could provide some meaningful guides in pratical application of terahertz functional devices..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1832 (2015)
De-noising research on terahertz digital holography based on wavelet transform
Cui Shanshan, and Li Qi
Terahertz digital holography is one of the research hotspots in the terahertz imaging field over the world nowadays. The real reconstructed image was used as the research object, which was achieved by the continuous terahertz inline digital holographic imaging system, and the de-noising research was studied based on waTerahertz digital holography is one of the research hotspots in the terahertz imaging field over the world nowadays. The real reconstructed image was used as the research object, which was achieved by the continuous terahertz inline digital holographic imaging system, and the de-noising research was studied based on wavelet transform. Wavelet threshold technique and the homomorphic filtering based on wavelet were applied to denoise the image, with hard threshold and soft threshold technique respectively, by "bior2.2" and "sym4" wavelet base. Then the denoising result was quantitatively assessed. The experimental results show that the homomorphic filtering based on wavelet has the best de-nosing performance for the reconstructed image of terahertz continuous inline digital hologram, which works with soft threshold method and the "bior2.2" wavelet basis..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1836 (2015)
[in Chinese]
Geometric parameters analysis of large FOV space camera when rolling
Cheng Shaoyuan, Zhang Li, Gao Weijun, and Wang Jinqiang
To precisely calculate geometric parameters of large field view space camera, such as object distance, projection angle, ground sampling distance, swath width, the precise calculation method of above-mentioned geometric parameters was studied，including nadir imaging and rolling imaging. Considering earth curvature and To precisely calculate geometric parameters of large field view space camera, such as object distance, projection angle, ground sampling distance, swath width, the precise calculation method of above-mentioned geometric parameters was studied，including nadir imaging and rolling imaging. Considering earth curvature and projection angle, geometric model was constructed, the calculation method was improved to heighten precision. The analysis shows that, for a large field of view space camera on 650 km orbit altitude, with 20° half field of view and 20° roll, the maximum GSDx is 2.31 times of the minimum GSDx, is 1.78 times of the approximate GSDx. The maximum GSDy will become 7.16 times the minimum GSDx, is 4.29 times of the approximate GSDy. The swath width is 1.33 times of the approximate swath width. Therefore, the traditional calculation method is inaccurate, the precise calculation method of geometric parameters in this paper is useful for the imaging quality..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1872 (2015)
A novel method for calibrating intrinsic parameters of linear array cameras based on collinear feature points
Wang Lan, Sun Bo, Long Changyu, Zou Jian, and Zhu Jigui
A novel method was proposed that can be used for determining intrinsic parameters of linear array cameras based on collinear calibration feature points. All calibration feature points were on the view plane of the linear array camera. Firstly, during the camera calibration the feature point was captured by the camera oA novel method was proposed that can be used for determining intrinsic parameters of linear array cameras based on collinear calibration feature points. All calibration feature points were on the view plane of the linear array camera. Firstly, during the camera calibration the feature point was captured by the camera one by one, the corresponding image point and the spatial feature point were obtained directly, which solved the matching problem of the spatial feature point and image point. Secondly, a mathematical model was established to obtain the imaging model of the linear array camera, then use the simultaneous imaging models of multiple locations was used to calculate the camera intrinsic parameters; Finally, the impacts on the calibration result were analyzed and experimented. Result reveals that the proposed linear array camera calibration method is not only convenient and flexible, but also sophisticated calibration pattern is not required, and a lot of calibration points are obtained which improving the accuracy and stability of the line scan camera calibration. The root mean square error of re-projected points is less than 0.37 pixel..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1878 (2015)
TMT M3 mirror figure measurement with slope method
An Qichang, Zhang Jingxu, Yang Fei, and Qiao Bing
The slope methods was introduced to measure the TMT M3 mirror figure. First of all，the low order aberrant and middle spatial frequency aberrant were studied for the search of property plan to test and analyse them. Then the problem was considered numerically for the prove of theory, furthermore, the experiment was alsoThe slope methods was introduced to measure the TMT M3 mirror figure. First of all，the low order aberrant and middle spatial frequency aberrant were studied for the search of property plan to test and analyse them. Then the problem was considered numerically for the prove of theory, furthermore, the experiment was also done to confirm the feasibility of this plan. Lastly, for the error budget of this system, the Monte Carlo method was introduced to allocate the error to the instrument of the sub-system for request of TMT. The tertiary mirror of TMT and other reflecting mirror frequency feature, and quantification could be measured. As a result, it could give more sufficient technical guidance on the testing for the large aperture reflect mirror..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1884 (2015)
FOV determination of the three FOVs position and orientation determination equipment
Wang Haojing, Wang Jianli, Wu Liang, and Yao Kainan
In order to improve the three FOVs position and orientation determination equipment reliability, the basic constraints test probability distribution model of the three FOVs system was established. Based on the model, the optimized FOV size of the equipment was analyzed on the visible band. First, the necessary conditioIn order to improve the three FOVs position and orientation determination equipment reliability, the basic constraints test probability distribution model of the three FOVs system was established. Based on the model, the optimized FOV size of the equipment was analyzed on the visible band. First, the necessary conditions of the composite FOVs star identification and the sample FOV star identification were analyzed, and the probability distribution models of the methods were established. The reason why probability distribution of recognized triangles on three FOVs equipment cannot be simply deduced from the one FOV′s was illuminated in theory and simulated experiment. Then, the optimal value of the probability distribution was obtained by the monte Carlo method. Finally, the optimal design of the FOV size was presented by computer simulation. The experimental results show that: the three FOVs celestial navigation equipment using the composite FOVs star identification is more reliable. The optimal FOV size is 4.225°×3.168 75°. It can satisfy the reliability requirements of the three FOVs position and orientation determination equipment..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1890 (2015)
Gimbals periodic error suppression based on fiber optic gyroscope
Yang Yongqing, Liang Yanbin, Li Zhiguo, and Liang Dongsheng
In order to suppress the periodic angle measuring error′s fluctuation on gimbals and the imaging effect of photoelectric tracking, a measuring error model and an error control algorithm were established. Firstly, the mechanism of the measurement error of angular measuring system was analyzed, and a mathematical model fIn order to suppress the periodic angle measuring error′s fluctuation on gimbals and the imaging effect of photoelectric tracking, a measuring error model and an error control algorithm were established. Firstly, the mechanism of the measurement error of angular measuring system was analyzed, and a mathematical model for the periodic error was established in this paper. Secondly, a measuring error acquisition system based on the high precision fiber optic gyroscope and Fourier was established, and a specific expression of angle measurement error model was established through seven experimental procedures. Then, the periodic system error was compensated according to the measured angle error expressions through four steps. Finally, the effectiveness of control compensation was verified by tracking imaging experiments, and the experimental results show that speed error is reduced to 0.04 (°)/s, is reduced 8 times. The error meets the requirement of the imaging system less than 0.1 (°)/s, and the stripe imaging effect is greatly improved..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1898 (2015)
Line-of-sight stabilization techniques for mirror electro-optical platform
Song Jiangpeng, Sun Guangli, Zhou Di, and Cai Huimin
According to diversity characteristics of the line-of-sight(LOS) kinematics in various mirror platforms, a general method based on the artificial mass stabilization platform was proposed to reconstruct LOS inertial angle rate in various mirror platforms by employing the basic mirror kinematics equations. Then, the LOS According to diversity characteristics of the line-of-sight(LOS) kinematics in various mirror platforms, a general method based on the artificial mass stabilization platform was proposed to reconstruct LOS inertial angle rate in various mirror platforms by employing the basic mirror kinematics equations. Then, the LOS kinematics and the LOS stabilization techniques of several common mirror platforms just like the typical single mirror platform, the special configuration single mirror platform, the polar coordinate multi-mirror platform and the orthogonal coordinate multi-mirror platform were analyzed deeply. Lastly, the simulation results of elevation gimbal for the typical single mirror platform show that the method based on the artificial mass stabilization platform is feasible for various mirror LOS stabilization control..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1904 (2015)
Calibration method of TCP based on stereo vision robot
Liu Changjie, Ban Rongxing, Guo Yin, Yin Shibin, and Wang Yi
The TCP of robot is the fundation of off-line programming and end error correction. Studying fast and accurate calibration method is vital to ensure robots work normally in industrial field environments. In this paper, a TCP automatic calibration method was presented based on binocular vision measurement,combined with The TCP of robot is the fundation of off-line programming and end error correction. Studying fast and accurate calibration method is vital to ensure robots work normally in industrial field environments. In this paper, a TCP automatic calibration method was presented based on binocular vision measurement,combined with the spatial coordinate transformation theory and robot kinematics, which is applicable to industrial manufacturing site. This method has several advantages of non-contact, fast and high precision, which can reduce errors coming from previous calibrating method of contactless measurement and overcome its shortcoming of slowness. This method was testified on ABB robot and then experiment result shows that the accuracy is much better than that of conventional method when the calibration tool having a diameter of 10 mm. It can meet high precision, fast TCP calibration requirements in industrial site..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1912 (2015)
Measurement of atmospheric coherence length of optical propagation along long distance path
Kang Li, and Zhu Wenyue
Atmospheric coherence length over a nearly horizontal and 3.95 km path was experimental studied by the large aperture scintillation and differential image motion measure angle-of-arrival fluctuation methods. For two direction (up and down) of the same path, the experiment results show that the correlation coefficient oAtmospheric coherence length over a nearly horizontal and 3.95 km path was experimental studied by the large aperture scintillation and differential image motion measure angle-of-arrival fluctuation methods. For two direction (up and down) of the same path, the experiment results show that the correlation coefficient of the large aperture scintillation method is 0.94, while the correlation coefficient of differential image motion measure angle-of-arrival fluctuation method is 0.79. Analysis of path weight function reveals that scintillation is most sensitive to the eddy in the center of the path and its path weight function is symmetrical in the measured path; however, DIMM is most sensitive to the eddy near the receiver and its path weight function is increased monotonically along with measured path from transmitter to receiver. Therefore, the scintillation maybe more appropriate for measuring turbulent effects when light propagate along long distance path whose turbulence intensity distribution is indistinct..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1918 (2015)
Calculation of external heat fluxes on space camera with changing attitudes frequently in Geomagnetic Coordinate system
Yang Huabin, Wu Qingwen, Chen Liheng, He Fei, and Zhang Xusheng
In order to provide the external heat flux of space camera accurately, a method was proposed to calculate the instantaneous external heat fluxes of a space camera with changing attitudes frequently depending on its position in the Geomagnetic Coordinate system(MAG). First, in J2000 Coordinate the relative position of tIn order to provide the external heat flux of space camera accurately, a method was proposed to calculate the instantaneous external heat fluxes of a space camera with changing attitudes frequently depending on its position in the Geomagnetic Coordinate system(MAG). First, in J2000 Coordinate the relative position of the sun, earth and radiation intensity of sun was calculated. Second, geomagnetic latitudes of a camera and orbital times when camera entered or exited from high geomagnetic latitudes(L≥60°) were calculated. Then, the camera′s attitudes were ensured with geomagnetic latitudes. Finally, orbital view factors of six mapping planes were achieved by the Monte Carlo Method(MCM)and the instantaneous external heat fluxes was obtained during the on-orbit time. The external heat fluxes of this paper were consentaneous with the software IDEAS/TMG. Compared with the stable attitude camera, the attitude varieties of the camera take a relatively strong influence on the external heat flux, especially for the +Z-direction where optical entrance is located. The fluctuation range of the +Z-direction external heat flux is about 0-1 245.4 W/m2..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1923 (2015)
[in Chinese]
Lateral force study on conditions under IR Bragg grating
Zhang Zhen, Ma Pengge, Wang Jinfeng, and Sun Junling
How to solve the optical fiber transmission dispersion compensation, as well as to achieve high-speed data-intensive wave of all-optical time division multiplexing and multiplexing solution, become a major problem during the study. Fiber Bragg Grating(FBG)is an ideal passive sensing and signal demodulation device, the How to solve the optical fiber transmission dispersion compensation, as well as to achieve high-speed data-intensive wave of all-optical time division multiplexing and multiplexing solution, become a major problem during the study. Fiber Bragg Grating(FBG)is an ideal passive sensing and signal demodulation device, the lateral force characteristics of fiber Bragg grating was explored, and an experimental system ASE100 source was built. Demodulation results show that：loss of polarization had maximum transmittance spectrum of the main stop band; split point was linear relationship with size of the force, and generated to move with the periodic variation of the force; different temperatures did not change the shape of the loss of polarization, but it was generated at the position of the wavelength axis. The research results for the clear fiber Bragg grating lateral force has significant reference value..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1841 (2015)
A novel fiber-optic distributed disturbance sensor system with low false alarm rate
Lin Wentai, Liang Sheng, Lou Shuqin, Sheng Xinzhi, Wang Peng, and Zhang Yan
A phase-sensitive optical time domain reflectometer(φ-OTDR) and Mach-Zehnder interferometer based fiber-optic distributed disturbance sensor was proposed in this paper. The aim is to obtain a low false alarm rate compared with current single φ-OTDR, which suffers from the high false rate due to the instability of scattA phase-sensitive optical time domain reflectometer(φ-OTDR) and Mach-Zehnder interferometer based fiber-optic distributed disturbance sensor was proposed in this paper. The aim is to obtain a low false alarm rate compared with current single φ-OTDR, which suffers from the high false rate due to the instability of scattering light intensity fluctuation in φ-OTDR. In the proposed sensor, φ-OTDR and Mach-Zehnder interferometer were multiplexed together. So, the φ-OTDR was used to detect and locate the disturbance, and the Mach-Zehnder interferometer was utilized to detect the disturbance, respectively. Then, the disturbance detected by φ-OTDR can be confirmed by the M-Z interferometer to realize a low false alarm rate due to the instability of φ-OTDR. The feasibility and effectivity of the proposed method by multiplexed φ-OTDR and Mach-Zehnder interferometer were validated in experiment, by comparing with current single φ-OTDR. It is found that the false alarm rate can be reduced to 2% from 25% by the single φ-OTDR..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1845 (2015)
Analysis on error rate of wireless optical communication using subcarrier modulation based on polar code
Ke Xizheng, Lei Sichen, Shao Junhu, and Chen Qiang
A novel polar coded subcarrier phase shift keying modulation method suitable for wireless optical communication system was proposed in this paper. Then their encoding and decoding procedures were presented for polar coding schemes over the atmospheric turbulence channels. By simulating the system performance under variA novel polar coded subcarrier phase shift keying modulation method suitable for wireless optical communication system was proposed in this paper. Then their encoding and decoding procedures were presented for polar coding schemes over the atmospheric turbulence channels. By simulating the system performance under various atmospheric turbulence conditions, the bit error rate(BER) performance were compared between binary phase shift keying modulation with polar code(BPSK-PC) and quaternary phase shift keying modulation with polar code(QPSK-PC). The results show that the error correction performance of BPSK-PC system is better than that of QPSK-PC system. Finally, the experimental BER performance of the subcarrier phase shift keying modulation with and without polar code were conducted and analyzed as well. The experimental results show that the proposed method can improve the BER performance with an order of magnitude, by using polar code in wireless communication system together with subcarrier phase shift keying modulation..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1849 (2015)
Design and implementation of electro-optic modulator adaptive polarization control system
Li Yongqian, Meng Xiangteng, An Qi, Lv Anqiang, Wang Yue, and Wang Yu
In order to keep the input light polarization direction of electro-optic modulator(EOM) up with that of internal propagation mode in an EOM, and to obtain expected modulation effect, an adaptive control method based on proportional-integral-derivative(PID) algorithm was proposed. Theoretical analysis and experimental dIn order to keep the input light polarization direction of electro-optic modulator(EOM) up with that of internal propagation mode in an EOM, and to obtain expected modulation effect, an adaptive control method based on proportional-integral-derivative(PID) algorithm was proposed. Theoretical analysis and experimental demonstration was conducted to verify the feasibility of the proposed method. The experimental results show that the control system designed by the method not only can real-time monitor the output optical power of EOM, but also can keep the output power maximum. Compared with the performance of EOM conncted directly to a narrow band laser with a polarization maintaining fiber, the output average power of EOM under the polarization control based on PID is increased by 3.08 dB and the standard deviation of PD output voltage is reduced from 0.121 4 to 1.237 5×10-4. And the correction time for the state of polarization is in the order of ms when the system is working in stable control state..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1854 (2015)
Application of the genetic algorithm in the demodulation of the FBG cross-sensitivity characteristics
Liu Chaoming, and Lou Shuqin
Fiber Bragg gratings (FBGs) have been widely used in the modern sensing field, but the cross-sensitivity characteristics between temperature and strain greatly confine its application in optical fiber sensing system. In this paper, a demodulation scheme was proposed based on genetic algorithm. A fast demodulation modelFiber Bragg gratings (FBGs) have been widely used in the modern sensing field, but the cross-sensitivity characteristics between temperature and strain greatly confine its application in optical fiber sensing system. In this paper, a demodulation scheme was proposed based on genetic algorithm. A fast demodulation model of genetic algorithm was established. According to the mathematical analysis, the genetic algorithm fitness function and target equation were determined. With the proposed scheme, the demodulation results for different center wavelengths and peak reflections of the two FBGs were discussed. Numerical results demonstrate that the proposed demodulation scheme based on genetic algorithm can effectively demodulate the change of the temperature and strain separately without the requirement of two same fiber grating in the method of the traditional reference fiber grating. The accuracy of temperature and strain measurement are 0.1 ℃ and 1.5 με, respectively. This scheme can make the construction of fiber sensing system easier..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1859 (2015)
Signal detection of an optical fiber surface plasmon resonance sensor
Zheng Yan, Xing Liyun, Chang Tianying, Wang Min, Sun Yufeng, Cui Hongliang, Liu Ye, and Zhao Yue
The optical fiber surface plasmon resonance (SPR) sensor is an advanced and high-precision sensor, used mainly in environmental pollution detection and detection of biopolymers. Firstly, based on the plasmon resonce sensing theory, the estimate of meaning linear model was obtained by a discussion of our experimental reThe optical fiber surface plasmon resonance (SPR) sensor is an advanced and high-precision sensor, used mainly in environmental pollution detection and detection of biopolymers. Firstly, based on the plasmon resonce sensing theory, the estimate of meaning linear model was obtained by a discussion of our experimental results and the system's data-processing issue. Then, based on the estimate of meaning linear model, a number of groups of a solutions were measured at different times and under the same circumstances and their spectral data was obtained, leading to the estimate of the effective resonance wavelength. Secondly, a wavelet analysis for the SPR reflected spectrum is carried out. The deviation of the resonant wavelength caused by noise was corrected, and the experimental data was filtered by a wavelet analysis, improving the system precision. Parameters impacting the fiber-optic SPR sensor performance were analyzed by theoretical calculation and simulation used Matlab, to optimize the sensing system design. Differences of the refractive index of test solutions such as distilled water, alcohol, etc, have been measured. Our design of the optical fiber SPR sensing systems was proved to be feasible and worked well. The result shows the relationship between the refractive index and SPR wavelength that is well linear within the measurable refractive index range..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1865 (2015)
[in Chinese]
Dual color QWIP FPA with MW/LW switchable architecture
Li Dongsheng, Zhou Xuchang, Wang Bo, and Mu Yingchun
The development of the the MWIR/ LWIR dual color quantum well infrared FPA with the architecture switching between MWIR and LWIR was reported. The architecture including chip and read-out circuit (ROIC) frame was specially designed to realize the selection and switch of the MW band and LW band. The QWIP FPA key technolThe development of the the MWIR/ LWIR dual color quantum well infrared FPA with the architecture switching between MWIR and LWIR was reported. The architecture including chip and read-out circuit (ROIC) frame was specially designed to realize the selection and switch of the MW band and LW band. The QWIP FPA key technologies such as quantum well material epitaxy, chip preparation and ROIC were described. The dual color 25 μm pitch 384×288 QWIP FPA is realized with the excellent noise equivalent temperature difference (NETD) of 28 mK in the MWIR and 30 mK in the LWIR at a operating temperature of 70 K. The peak wavelength is 5.1 μm for MWIR and 8.5 μm for LWIR. The infrared image of the target at room-temperature demonstrates the dual color detection function of the FPA..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1681 (2015)
IRFPA ROIC integrated digital output
Gao Lei, Zhai Yongcheng, Liang Qinghua, Jiang Dazhao, and Ding Ruijun
In order to achieve infrared focal plane digital output, an IRFPA readout circuit integrated on-chip ADC was designed, including a 512×512 cell array readout circuit and shared the successive approximation register analog to digital converters(SAR ADC). Unit readout circuit using direct injection (DI) structure asIn order to achieve infrared focal plane digital output, an IRFPA readout circuit integrated on-chip ADC was designed, including a 512×512 cell array readout circuit and shared the successive approximation register analog to digital converters(SAR ADC). Unit readout circuit using direct injection (DI) structure as the input stage, the output signal was sent through the multiplexes to ADC. The comparator designed in successive approximation ADC was a high-speed comparator which consisted of the preamplifier, latches, self-biasing differential amplifiers and output drives. The digital to analog converter (DAC) used a three-stage structure which the charge scaling was combined of voltage scaling. Using the Cadence and Synopsys design platform for circuit′s design, simulation and layout design. The circuit was taped out by GLOBALFOUNDRIES company using 0.35 μm, 3.3 V CMOS process. Test results show the number of significant digits of ADC is 8.2 bit, converts frequency is 150 k Samples/s, power consumption less than 300 μW and meet the needs of focal plane 100 frame rates as well as low power consumption..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1686 (2015)
Study on atmospheric transmittance of thermal infrared remote sensing(I): derivation of atmospheric transmittance model
Gong Shaoqi, Sun Haibo, Wang Shaofeng, Guo Wenzhe, and Li Yunmei
Atmospheric transmittance is an important parameter in the thermal infrared remote sensing. A multi-variable lookup table of atmospheric transmittance which includes atmospheric model, aerosol model, water vapor content, visibility and view zenith angle was constructed based on the radiation transfer model MODTRAN, effAtmospheric transmittance is an important parameter in the thermal infrared remote sensing. A multi-variable lookup table of atmospheric transmittance which includes atmospheric model, aerosol model, water vapor content, visibility and view zenith angle was constructed based on the radiation transfer model MODTRAN, effect of different parameters on thermal infrared atmospheric transmittance spectrums was analyzed, the key variables of atmospheric transmittance were determined by the analysis of variance. According to different types of aerosol model, the multi-variable linear regression models of atmospheric transmittance models were deduced based on the water vapor content, visibility and view zenith angle for common thermal infrared sensor channels, which will solve the problem on calculating accurately the atmospheric transmittance for the thermal infrared remote sensing by satellite..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1692 (2015)
Effect of reflected background radiation by skin on infrared signature of subsonic aircraft (Ⅰ): methodology
Huang Wei, and Ji Honghu
Based on the flow field and temperature field results calculated by CFD code and the environment data calculated by Modtran, the calculation model of the infrared radiation signature of aircraft under typical background was established. The factors of the wave band, season, emissivity and bidirectional reflectance distBased on the flow field and temperature field results calculated by CFD code and the environment data calculated by Modtran, the calculation model of the infrared radiation signature of aircraft under typical background was established. The factors of the wave band, season, emissivity and bidirectional reflectance distribution function were calculated. The calculation method was verified through a ground test data, and the calculation data is in good agreement with the experimental data. This model can provide a method and tool for more accurate analysis of aircraft′s infrared radiation signature and more reasonable evaluation of infrared suppression methods..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1699 (2015)
Impacts of two-dimensional curved mixing duct exit geometric parameters on flow dynamics and infrared radiation characteristics for IR suppressor
Chen Geng, Tan Xiaoming, Shan Yong, and Zhang Jingzhou
Based on general CFD/IR numerical simulations, the effects of two-dimensional curved mixing duct geometric parameters on helicopter aerodynamics and infrared radiation characteristics were investigated. Conclusions can be drawn as follows according to the computational results: Compared with two-dimensional curved mixiBased on general CFD/IR numerical simulations, the effects of two-dimensional curved mixing duct geometric parameters on helicopter aerodynamics and infrared radiation characteristics were investigated. Conclusions can be drawn as follows according to the computational results: Compared with two-dimensional curved mixing duct with rectangular outlet, the distorted configurations of mixing duct lobed rectangular outlet extend the perimeter of exhaust exit, thus the strength of the secondary flow shed by lobes is enhanced due to the effective shear-mixing caused by viscous and shear force, which contributes to a maximum increase about 19.2％ in pumping capacity of the overall IR suppressor. Simultaneously, wall temperature of mixing duct is reduced significantly and the maximum infrared radiation intensity is decreased about 13.3％ to its highest when changing the shape of mixing duct outlet from rectangle to rectangular lobe. When the lobe heights of mixing ducts remain unchanged, with the increase of lobe numbers, the pumping ratio of IR suppressor firstly increases then decreases, while the total pressure recovery coefficient firstly decreases then increases. In addition, when the lobe numbers of remain unchanged, with the increase of lobe heights, the pumping ratio rises gradually, but the total pressure recovery coefficient keeps declining, and in this situation, the infrared radiation intensity peak achieve a maximum decrease about 11.6％..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1704 (2015)
Automated vacuum system for lifetime test of IR detectors
Cao Lan, Deng Ruohan, and Gong Haimei
During the lifetime test of IR component, the component needed to remove from its vacuum chamber of lifetime test in every parameter measurement, however, the movement may destroy the IR component. To deal with this problem, an automated, multi-station vacuum system for infrared component lifetime test was presented inDuring the lifetime test of IR component, the component needed to remove from its vacuum chamber of lifetime test in every parameter measurement, however, the movement may destroy the IR component. To deal with this problem, an automated, multi-station vacuum system for infrared component lifetime test was presented in this paper. By use of a specially designed Dewar as the lifetime test center, it achieved the situ parameter measurement. By the vacuum calculation and computer 3D modeling, the structural of the system was designed. By use of system programmable logic controller (PLC) as the control center, it achieved real-time monitoring and failure alarm protection of the vacuum environment for the lifetime test. Finally, exhaust gas experiment is performs and the results shows that the vacuum system operates normally, and the no-load vacuum pressure is up to 3.67×10-6 Pa in the case of liquid nitrogen cooling, which meet the requirement of the long-term lifetime test for space application of infrared detector assembly..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1712 (2015)
Experiment of the thermo-radiation characteristic of infrared window of hypersonic vehicles
Wang Yahui, Wang Qiang, Zhang Bochuan, Zhou Bin, Xiao Liping, and Xu Li
When hypersonic vehicles have flights in atmosphere, the temperature of the window of infrared (IR) detection systems rise rapidly, due to the aerodynamic heating by hypersonic airflow around. High-temperature IR windows dominate the aero-thermo-radiation effect, which reduce the performance of IR detection systems, inWhen hypersonic vehicles have flights in atmosphere, the temperature of the window of infrared (IR) detection systems rise rapidly, due to the aerodynamic heating by hypersonic airflow around. High-temperature IR windows dominate the aero-thermo-radiation effect, which reduce the performance of IR detection systems, including detection range, identification probability, tracking precision, and so on, or even make these systems fail. By simplifying radiation transfer model for IR windows, an experiment platform was designed to measure thermal-radiation characteristics of IR windows. On the platform, the experiment on thermal-radiation characteristics of a sapphire window were studied, in 3.7-4.8 μm. The research result indicates that, in 100-350 ℃, the higher the temperature of the sapphire IR window is, the smaller the transmittance is, and the stronger the self-radiation is. Both the transmittance and the self-radiation are related to the third power of the window temperature. From 100 ℃ to 350 ℃, the transmittance of the window drops about 16%, otherwise the self-radiation enhances above 100 times, of which the influence on the MWIR detection system is bigger than that of transmittance..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1716 (2015)
Influence of multilayer heat insulation material on infrared feature of a satellite
Wu Xiaodi
As to the deficiency of ignoring multilayer heat insulation material or simply taking its heat transfer process equivalently as the thermal insulation steady state process in infrared characterization research of spatial targets, the factual heat transference ways of multilayer heat insulation material were considered As to the deficiency of ignoring multilayer heat insulation material or simply taking its heat transfer process equivalently as the thermal insulation steady state process in infrared characterization research of spatial targets, the factual heat transference ways of multilayer heat insulation material were considered and the temperature calculation models of multilayer heat insulation material′s radiation heat transfer, solid thermal conduction and residual gas thermal conduction were established. On the base of the models, the influence of different heat transference ways of multilayer heat insulation material on a satellite′s surface temperature and infrared feature in 3-6 μm band and in 6-16 μm band was calculated and analyzed. The calculation results show different heat transference ways of multilayer heat insulation material have more influence on the satellite′s infrared feature in 6-16 μm band than in 3-6 μm band. The research result has referential value for improving infrared feature calculation precision of spatial targets..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1721 (2015)
Numerical simulation of radiation intensity of double S-shaped exhaust system with different outlet shapes
Gao Xiang, Yang Qingzhen, Shi Yongqiang, Wang Yun, and Yang Huicheng
Several double-S nozzles with different outlet shapes were designed based on an axis-symmetric nozzle to analyze influence of the outlet shape on the infrared radiation(IR) characteristics of exhaust system. The curvature regulation method and mass-flow matching principle were adopted in the design. The distribution ofSeveral double-S nozzles with different outlet shapes were designed based on an axis-symmetric nozzle to analyze influence of the outlet shape on the infrared radiation(IR) characteristics of exhaust system. The curvature regulation method and mass-flow matching principle were adopted in the design. The distribution of the characteristics of flow field and mass fraction of six exhaust system models were obtained by CFD. The IR characteristics of these models were calculated by reverse Monte-Carlo method (RMCM), and then IR intensity space distribution of the rear hemisphere, radiation brightness distribution and the lock distance of the rear hemisphere were researched. The results show that, the double S-shaped nozzle can reduce the infrared signal of target effectively. The outlet shape can affect the IR characteristics of exhaust system. The models with trapezoid outlet shape has significantly lower IR intensity than the double S-shaped nozzles with other outlet shapes, and can reduce the peak of IR intensity at least 70% compared with the axis-symmetric nozzle. Reducing trapezoid′s bottom angle can enhance the infrared suppression effect, and appropriate outlet shape can further suppress the IR intensity of exhaust system within acceptable thrust loss..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1726 (2015)
Applications of ASIC in the long array column of infrared TDI detector
Han Bing, Chen Xin, Rao Peng, Lin Changqing, Sun Shengli, and Li Lufang
There always exist some challenges in long array column infrared Time Delay Integration(TDI) detecting system, such as large number of channels, high noise and power dissipation. To solve those problems mentioned above, a new solution was proposed to improve the performance of infrared TDI detecting system with ApplicaThere always exist some challenges in long array column infrared Time Delay Integration(TDI) detecting system, such as large number of channels, high noise and power dissipation. To solve those problems mentioned above, a new solution was proposed to improve the performance of infrared TDI detecting system with Application Specific Integrated Circuit(ASIC) chip(eight-channel signal conditioning chip). Meanwhile, it helped to light the weight and reduce the system volume. In the system, the noise and dissipation both reduced to half than before. The average noise of system was 1.42 mV with power of 0.73 W. More higher integration was achieved by Readout Integrated Circuit(ROIC), design complexity and workload were reduced. It provides technical support and practical foundation for micro miniaturization aerospace remote sensing satellite development..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1733 (2015)
Application of chalcogenide glasses in designing vehicle-mounted infrared imaging lens for civilian applications
Jiang Bo, Wu Yuehao, Dai Shixun, Zhang Wei, Zhang Peiqing, Wang Xunsi, Shen Xiang, and Nie Qiuhua
A vehicle-mounted infrared lens was designed based on 324×256 uncooled detector. The operating wavelength range of the lens is from 8 μm to 12 μm, the effective focal length(EFL) is 9 mm, the F number is 1.3, and the field of view(FOV) is 33.26°×26.28°. The proposed lens was designed as a combinatioA vehicle-mounted infrared lens was designed based on 324×256 uncooled detector. The operating wavelength range of the lens is from 8 μm to 12 μm, the effective focal length(EFL) is 9 mm, the F number is 1.3, and the field of view(FOV) is 33.26°×26.28°. The proposed lens was designed as a combination of two singlet lenses fabricated with the novel chalcogenide glass material Ge28Sb12Se60 and two singlet lenses fabricated with conventional infrared materials Germanium(Ge) and Zinc Sulfide(ZnS). Utilizing the differences in the thermal-optical properties of the utilized infrared materials, an athermalized optical design was realized by carefully adjusting the optical powers of the four singlets. Moreover, taking advantage of the superior property of chalcogenide glasses for molding preparation of aspherical surfaces, the imaging quality of the proposed lens could be further improved by introducing one aspherical surface on one of the chalcogenide glass singlets. The imaging quality of the proposed lens is close to the diffraction-limited system for the designed spectral range and for the temperature range from -40 to 60 ℃..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1739 (2015)
[in Chinese]
Influence of frequency shift of pump laser on photoacoustic signal for frequency stabilization
Guo Xiaoyang, Li Ting, Wang Du, Zhong Zheqiang, Meng Qinglong, and Zhang Bin
The frequency stability of CO2 pumping laser is of great importance for optically pumped terahertz(THz) gas laser. Aimed at frequency stabilization technique based on photoacoustic effect, the influence of detective conditions on the detection of weak photoacoustic signal in photoacoustic cell was theoretically analyzeThe frequency stability of CO2 pumping laser is of great importance for optically pumped terahertz(THz) gas laser. Aimed at frequency stabilization technique based on photoacoustic effect, the influence of detective conditions on the detection of weak photoacoustic signal in photoacoustic cell was theoretically analyzed and numerically simulated and the detective conditions were further optimized for high-precision detection of photoacoustic signal, including the pressure of methanol gas and the microphone sensitivity. On the basis, the variation of photoacoustic signal with the frequency shift of the pump laser from the center of the absorption line was analyzed. The results show that the low pressure condition and highly sensitive microphone are the keys for achieving high-precision photoacoustic frequency stabilization. When the laser frequency of CO2 pumping laser shifts from the center of the absorption line, the cavity length can be adjusted accurately by the regulation of feedback photoacoustic signal to ensure the frequency stability of output laser, and the frequency shift could be controlled within the magnitude of megahertz..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1746 (2015)
Study of micro-laser with photonic crystal waveguide
Hu Chunhai, Guo Shiliang, and Li Xin
The transmission and frequency characteristics of the micro-laser with photonic crystal waveguide were analyzed in this paper based on the finite-difference-domain(FDTD) method. The results demonstrate that, compared with the pure random media or pure photonic crystal waveguide, the light in defect area with random medThe transmission and frequency characteristics of the micro-laser with photonic crystal waveguide were analyzed in this paper based on the finite-difference-domain(FDTD) method. The results demonstrate that, compared with the pure random media or pure photonic crystal waveguide, the light in defect area with random media is obviously amplified, meanwhile the localization level becomes higher either. On the other hand, the interaction time between the random gain medium is prolonged, the loss and the threshold is reduced. In addition, the light can be modulated by the triangle lattice photonic crystal. The design of new device in this paper lay a theoretical foundation of integrated optical system and micro-laser with low threshold..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1752 (2015)
Stability improvement of DFB laser driving power using digital position PID algorithm
Zhan Juntong, Fu Qiang, Duan Jin, Zhang Su, Gao Duorui, and Jiang Huilin
To ensure the stability of output power of Distributed Feedback(DFB) lasers, which was effected by the emitting current, a high stable DFB lasers driver using positional digital PID algorithm was proposed. In terms of hardware design, the aforementioned driver was composed of controller model, constant current model anTo ensure the stability of output power of Distributed Feedback(DFB) lasers, which was effected by the emitting current, a high stable DFB lasers driver using positional digital PID algorithm was proposed. In terms of hardware design, the aforementioned driver was composed of controller model, constant current model and protection circuit model. The analog Proportion-Integral(PI) deep negative feedback loop was utilized to enhance the stability and precision of driving current effectively. In consider of software design, a positional digital PID algorithm was introduced to eliminate the micro deviation between the real driving current and the theory current value. Using the aforementioned driver, a driving test was performed on a DFB laser with a center wavelength at 1 563.01 nm. Experimental results show that long term(more than 100 h) stability is better than 4×10-5 and the center wavelength without any shift, which could provide DFBs with excellent performance security for the application of infrared gas detection..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1757 (2015)
Method of frequency modulated continuous wave laser modulation
Chen Huimin, Gao Zhilin, and Zhu Xiongwei
Frequency modulated continuous wave(FMCW)laser modulation circuit is an important part of the FMCW laser detection system. In this paper, the method of FMCW laser modulation was studied and a laser modulation circuit composed of a linear frequency modulation signal producing circuit and a semiconductor laser driver cirFrequency modulated continuous wave(FMCW)laser modulation circuit is an important part of the FMCW laser detection system. In this paper, the method of FMCW laser modulation was studied and a laser modulation circuit composed of a linear frequency modulation signal producing circuit and a semiconductor laser driver circuit was designed and implemented. Experimental result is given. The linear frequency modulation signal producing circuit was designed using the direct digital synthesis chip AD9958 and produced a 10-110 MHz sawtooth linear frequency modulation signal. The semiconductor laser driver circuit modulates the laser intensity with the linear frequency modulation signal through direct current modulation. Test results show that the laser modulation circuit can meet the design requirements：frequency deviation of 100 MHz, frequency modulation period of 100 μs..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1762 (2015)
Laser signal generating method in internal field simulation experiment
Fang Yanchao, Wang Jianjun, Yu Guoquan, Cui Shuang, and Li Yan
In order to make appraisal of the combat capability for laser-guided weapons in internal field, the laser signal simulation system was designed. First of all, for the composition of the laser signal simulation system and its working principle, the internal field simulation and equivalent methods of laser signal divergeIn order to make appraisal of the combat capability for laser-guided weapons in internal field, the laser signal simulation system was designed. First of all, for the composition of the laser signal simulation system and its working principle, the internal field simulation and equivalent methods of laser signal divergence angle, energy and direction were analyzed respectively, and the dynamic adjustment of the three devices was calibrated. The experiment results show that: The relative error of dynamic simulation of the laser signal spot diameter is less than 2.5%, the dynamic adjustment error of energy attenuation is less than 0.2 dB, dynamic adjustment error of azimuth and elevation are respectively less than 1.3 mrad, 0.6 mrad. The simulation system has been applied in the photoelectric countermeasure simulation project, and this simulation system can provide high degree of laser signal simulation for laser-guided weapons qualification test..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1766 (2015)
Discussion on feasibility of inserting the GSP into LCOS
Ni Lei, Shen Chuan, Li Hao, Liu Kaifeng, and Wei Sui
The liquid crystal on silicon(LCOS) is one of the most appropriate spatial light modulators for holographic video display but the off-the-shelf LCOS is not suited because of mainly its small diffraction angle and low resolution. Metasurface, for example, gap-surface plasmon (GSP), has recently emerged as an innovative The liquid crystal on silicon(LCOS) is one of the most appropriate spatial light modulators for holographic video display but the off-the-shelf LCOS is not suited because of mainly its small diffraction angle and low resolution. Metasurface, for example, gap-surface plasmon (GSP), has recently emerged as an innovative approach to control light propagation with unprecedented capabilities. In this paper, the feasibility of inserting one kind of metasurface into the LCOS was numerically discussed to deal with the problem. To the practical purpose, aluminum was used as the metal layer, the aluminum oxide layer was used as the insulating layer to form GSP structure. Firstly, the optical properties of aluminum at visible frequencies and the relative Fabry-Perot resonator model were studied. The preliminary structure then was inserted into LCOS to observe its effects on the electric field in the liquid crystal and consequently the changes of the liquid crystal director. The numerical simulations results show that the proposed structure has some influence on the diffraction of the far-field light and there are some changes in the viewing angle of the holographic display. The purpose of inserting the GSP into LCOS devices proposed here is technically feasible..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1773 (2015)
Ranging measurement based on linear frequency modulated continuous laser
Qu Yang, Wang Chunhui, Gao Jie, and Liao Yuandong
A ranging measurement based on Linear Frequency Modulated Continuous Laser(LFMCL) heterodynes method was investigated and the system of distance measurement was designed. Mixed the two linear frequency modulated laser beams of the same characteristics which were delayed by delay fiber in different time. Then get the frA ranging measurement based on Linear Frequency Modulated Continuous Laser(LFMCL) heterodynes method was investigated and the system of distance measurement was designed. Mixed the two linear frequency modulated laser beams of the same characteristics which were delayed by delay fiber in different time. Then get the frequency value which contains the ranging information, and simulated by Matlab-Simulink. By the procedure of the linear FM signal and simulation of the linear FM heterodyne ranging, get the the frequency difference of the heterodynes in the distance of 300 meter, 600 meter and 900 meter, the results show that simulation makes a coincidence with the theoretical arithmetic..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1779 (2015)
Arbitrary two-position north finder based on ring laser gyro and error analysis
Xue Haijian, Guo Xiaosong, Zhou Zhaofa, and Wei Wanning
An arbitrary two-position north finder based on ring laser gyro was introduced. It can save the time of north finder to a certain extent. The solver formula of north finder in the whole attitude was derived. In order to improve the accuracy of north finder, the impact of the various errors including the drift of gyro, An arbitrary two-position north finder based on ring laser gyro was introduced. It can save the time of north finder to a certain extent. The solver formula of north finder in the whole attitude was derived. In order to improve the accuracy of north finder, the impact of the various errors including the drift of gyro, system circumference error and position transposition error on the accuracy of the arbitrary two-position north finder was analyzed theoretically, and the mathematical model of errors were established, and the method of reducing the error was proposed. Simulation result indicates that the position transformation under the level state bringing error of north finder is a constant, and is half of the position transformation. In order to ensure an enough high accuracy of north seeking, it requires the corner μ≥40° and the latitude φ≤70° of north finder in the course. The results of north finder further validate the correctness of the simulation results, consistent with the theoretical analysis..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1784 (2015)
Transverse spot superresolution in femtosecond laser microfabrication
Cai Jianwen, Pan Xuetao, Zhang Meifeng, and Meng Fei
In femtosecond laser micromachining lateral distribution of the focus light spot directly affects laser machining accuracy, resolution and surface roughness. Focused spot was modulated by using laser beam spatial shaping technology, lateral ultra diffraction theory was studied and analyzed, One kind of tetracyclic lateIn femtosecond laser micromachining lateral distribution of the focus light spot directly affects laser machining accuracy, resolution and surface roughness. Focused spot was modulated by using laser beam spatial shaping technology, lateral ultra diffraction theory was studied and analyzed, One kind of tetracyclic lateral modulation phase plate was designed by using optimization algorithms. The radiuses of the phase plane are r1=0.16、r2=0.27、r3=0.49, the peak energy S is 0.38, the focal spot size GT is 0.74, sidelobe energy MT is 0.20. The experiments were processed using a photochromic material before and after adding the phase plate in a laser micromachining system, the experiments results show that the performance of this super-diffraction phase element is particularly desirable in the femtosecond laser micromachining system, which can reduce the size of the point..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1790 (2015)
[in Chinese]
Accurate fixation of adaptive optics fundus imaging field of view based on visual target guidance
Liu Ruixue, Zheng Xianliang, Xia Mingliang, Lu Xinghai, and Xuan Li
For the high imaging resolution of the adaptive optics (AO) fundus camera and the existence of the eye isoplanatic angle, a single adaptive optics imaging field of view was limited to 1 °. To get a complete fundus image, accurate fixation of one single field of view and image mosaicking of multiple fields of view For the high imaging resolution of the adaptive optics (AO) fundus camera and the existence of the eye isoplanatic angle, a single adaptive optics imaging field of view was limited to 1 °. To get a complete fundus image, accurate fixation of one single field of view and image mosaicking of multiple fields of view must be achieved. In order to accurately track fundus imaging area, the principle to guide imaging field of view with a visual target was analyzed and a novel visual target system was designed. Parallel light was used to illuminate the target and focused to the center of the human pupil through a lens before the eye. In this way, the retinal position of the imaging field of view could be precisely measured. The visual target guidance system was introduced into a liquid crystal adaptive optics camera. The imaging field ranged to 22.6°on the retina. The fixation accuracy was achieved to 0.003°. This set of adaptive optics system successfully tracked single retinal photoreceptor cell and got stitched images of fundus blood vessels, which was beneficial for application and popularization of liquid crystal AO system in clinical ophthalmology..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1794 (2015)
Transmission spectral characteristics of F-P interferometer under multi-factors
Shen Fahua, Xia Yiqi, Yu Aiai, and Liu Chenglin
Fabry-Perot interferometer(FPI) is an optical instrument with important scientific and practical value, which can be widely used in optical frequency discrimination, optical frequency locking and spectral measurements of the hyperfine structure. However, in practical applications, the spectral characteristics of the inFabry-Perot interferometer(FPI) is an optical instrument with important scientific and practical value, which can be widely used in optical frequency discrimination, optical frequency locking and spectral measurements of the hyperfine structure. However, in practical applications, the spectral characteristics of the interferometer are affected by many factors. In this article, the impact of several factors on Fabry-Perot interferometer spectral properties, such as the beam divergence angle, the spectrum of the incident light, the absorption loss, surface defects and non-parallelism of the interferometer two plates were studied in depth. Considering the above practical factors, a general expression for the transmission spectrum function of F-P interferometer was derived theoretically. The overall shift of the transmission spectrum caused by the divergence angle was given quantitatively. The concept of equivalent spectral width of the emitting laser was proposed, the broadening effects on the transmittance spectrum of the incident beam divergence angle, the spectrum of the incident light, surface defects and non-parallelism of the interferometer two plates were all considered, and their quantitative equivalent formula was given. These results would provide a reference for the design and application of Fabry-Perot interferometer..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1800 (2015)
Design of two-dimensional laser warning optical system
Li Xiao, Zhang Rui, Wang Zhibin, and Huang Yanfei
As an existing single laser warning system can only achieve a one-dimensional azimuth and wavelength information of the incoming laser light. A new method of single-laser warning system was proposed which can simultaneously measure two-dimensional azimuth and the wavelength information of the incoming laser light. The As an existing single laser warning system can only achieve a one-dimensional azimuth and wavelength information of the incoming laser light. A new method of single-laser warning system was proposed which can simultaneously measure two-dimensional azimuth and the wavelength information of the incoming laser light. The optical system consists of shade, grating, lens group and CCD array. Two-dimensional azimuth and wavelength information of the incoming laser light was measured by measuring the position of the zero-order and first-order diffraction. The basic principle was introduced, the equations of two-dimensional azimuth and wavelength measurement formula was derived. Depending on the project requirements, optical component parameters were deduced. The feasibility was verified through experiment. The experimental results show that the laser waring device can realize measurements of the incoming laser light, azimuth resolution no more than 1°, x direction field of view of 30°, y direction field of view of 15°..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1806 (2015)
Design method of collimating aspheric lenses based on PSO algorithm
Qin Hua, Feng Dongtai, Liu Bo, and Wu Guodong
An aspheric lens design method was presented for an application to LED collimating illumination. The method was derived from a basic geometric-optics analysis and the powerful optimization capability of particle swarm method. By using this method, a highly collimating aspheric lens based on a point source was designed.An aspheric lens design method was presented for an application to LED collimating illumination. The method was derived from a basic geometric-optics analysis and the powerful optimization capability of particle swarm method. By using this method, a highly collimating aspheric lens based on a point source was designed. To verify the practical performance of the collimating lens, a ray-tracing method was employed to trace light rays emitted from an ideal point light source through the collimating lens. The simulation results show that the lens works well with an ideal point and the maximum half view angle of light rays emitted from the lens is 0.004 60, for a 0.8 mm×0.8 mm LED source, the maximum half view angle of light rays emitted from the lens is 4.91°, which manifests the feasibility and effectiveness of Particle Swarm Optimization(PSO) algorithm applied to designing aspheric collimating lens. Compared with the conventional design method, this design approach is more intuitive and easier to implement..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1811 (2015)
Optical transmission effects of spherical dome by temperature and stress dynamic changing
Huang Xuanping, Xu Dong, Bao Shiqiu, and Tan Xiaosong
While high-speed aircraft are flying in the atmosphere, its optical-hood frictions with stream. The dome′s temperature and strain would change with the flight time going, which influences optical transmission because of the variation of the refractive index. The optical dome temperatures and stress-strain conditions vaWhile high-speed aircraft are flying in the atmosphere, its optical-hood frictions with stream. The dome′s temperature and strain would change with the flight time going, which influences optical transmission because of the variation of the refractive index. The optical dome temperatures and stress-strain conditions varying in the guidance process for different time periods were analyzed. By the method of ray tracing, OPD was calculated, and the result of optical transmission effect through optical image quality and image quality degradation was given. And the result shows that both temperature and speed of aircraft can influence optical transmission heavily..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1818 (2015)
[in Chinese]
Research and implementation of large field image real-time mosaic technology based on FPGA
Yang Lei, Ren Long, Liu Qing, Wang Hua, Zhou Zuofeng, and Cao Jianzhong
As a general rule, the software method is used to obtain large field images, which is not timely and convenient. In order to tackle the disadvantage of this method, based on FPGA, a kind of programmable technologies, a large field of view imaging system had put forward and achieved, which can fulfill the real time stitAs a general rule, the software method is used to obtain large field images, which is not timely and convenient. In order to tackle the disadvantage of this method, based on FPGA, a kind of programmable technologies, a large field of view imaging system had put forward and achieved, which can fulfill the real time stitching of the data from multiple cameras. Through the APTINA’s color CMOS image sensor MT9M034, the original image information had gained and then the real time data collection, data cache, stitching and transmission had accomplished centering on the Xilinx’s Virtex-5 FPGA. Firstly, the automatic adjustment of brightness differences of the original images was preprocessed in order to improve the overall mosaic effect. Secondly, information detection of relative shift amount was completed by the use of phase correlation method to register the original images. Finally, the two adjacent images’ overlap area was fused by the use of linear weighted fusion algorithm to make the mosaic image achieve a smoothly fading in and out transitional effect. Experimental results show that the imaging system is simple and reliable, and can effectively increase the field of view of observation. The stitched large field images are of high-definition and real time, with a certain degree of representativeness and practicality..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1929 (2015)
Object detection method based on objectness estimation and Hough forest
Hu Mengjie, Wei Zhenzhong, and Zhang Guangjun
Realizing effective and efficient object detection plays an important role in computer vision and has many practical applications including video surveillance and auto navigation. In order to improve the speed and accuracy of the existing detection methods, a simple yet effective object detection method coupled objectnRealizing effective and efficient object detection plays an important role in computer vision and has many practical applications including video surveillance and auto navigation. In order to improve the speed and accuracy of the existing detection methods, a simple yet effective object detection method coupled objectness estimation with Hough forest was proposed. Firstly, objectness estimation was utilized to generalize a set of object proposals based on bottom up visual attention mechanism of human vision system. Secondly, Hough forest object was adopted to localize the center of the object in the region of interest which was confirmed by object proposals put forward in the last step. Thirdly, the scale of the object proposal where the center was located was employed to determine the size of the object. A set of experiments demonstrate the effectiveness and efficiency of the proposed method..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1936 (2015)
Self-tuning hierarchical Kalman-particle filter for efficient target tracking
Xu Chao, Gao Min, and Yang Yao
Hierarchical Kalman-particle filter(HKPF) is successfully applied to target tracking with adaption to motion changes. However, it only focuses on the optimization of the target position rather than other affine parameters, resulting in many particles needed to find the optimal state. To achieve fast tracking in complexHierarchical Kalman-particle filter(HKPF) is successfully applied to target tracking with adaption to motion changes. However, it only focuses on the optimization of the target position rather than other affine parameters, resulting in many particles needed to find the optimal state. To achieve fast tracking in complex environment, self-tuning strategy-based hierarchical Kalman-particle filter was proposed to solve the problem. The proposed algorithm marginalized out the linear states in the dynamics to reduce the state dimension, and then found the optimal nonlinear states in a chainlike way with a very small number of particles. The detail process of our algorithm was as follows: first, a local region was estimated by KF; second, self-tuning strategy was used to incrementally generate particles in this region, and an online-learned pose estimator(PE) was introduced to iteratively tune them along the optimal directions according to observations. The comparison among the proposed algorithm and the existing tracking algorithms with real video sequences was implemented, in which the target undergo rapid and erratic motion, or/and dramatic pose change. The results demonstrate that the proposed tracking algorithm can achieve great robustness and very high accuracy with only a very small number of particles..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1942 (2015)
Distributed compression for hyperspectral images
Yang Xinfeng, Liu Yuanchao, Nian Yongjian, and Teng Shuhua
An efficient lossy compression algorithm was presented based on distributed source coding. The proposed algorithm employed multilevel coset codes to perform distributed source coding and a block-based scalar quantizer to perform lossy compression. Multi-bands prediction was used to construct the side information of eacAn efficient lossy compression algorithm was presented based on distributed source coding. The proposed algorithm employed multilevel coset codes to perform distributed source coding and a block-based scalar quantizer to perform lossy compression. Multi-bands prediction was used to construct the side information of each block, and the scalar quantization was performed on each block and its side information simultaneously. According to the principles of distributed source coding, the bit-rate of each block after scalar quantization was given. To reduce the distortion introduced by scalar quantization, skip strategy was employed for those blocks that containing high distortion in the sense of mean squared errors introduced by scalar quantization, and the block was directly replaced by its side information. Experimental results show that the performance of the proposed algorithm is competitive with that of transform-based algorithms. Moreover, the proposed algorithm has low complexity which is suitable for onboard compression of hyperspectral images..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1950 (2015)
Effect of ground attack strapdown guided weapons seeker disturbance rejection rate on the performance of guidance system
Yuan Yifang, Lin Defu, and Yang Tao
According to the problem of disturbance rejection rate(DRR) with strapdown imaging seeker, the transfer functions of DRR due to different scale and dynamic error between detector and angular rate gyro were established. With Routh criteria and coefficient freezing method, the stable region of guidance system with disturAccording to the problem of disturbance rejection rate(DRR) with strapdown imaging seeker, the transfer functions of DRR due to different scale and dynamic error between detector and angular rate gyro were established. With Routh criteria and coefficient freezing method, the stable region of guidance system with disturbance rejection rate parasitic loop(DRRPL) was analyzed, the value range of scale error and dynamic error under different non dimensional time was presented. The effect on guidance accuracy of DRR was studied by adjoint method. The research can provide technology reference to the guidance and control system design of strapdown guided weapons, more attention should be paid on the positive feedback situation of DRR..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 6, 1956 (2015)
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