Journals >Infrared and Laser Engineering
Contents
2015
Volume: 44 Issue 12
58 Article(s)
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[in Chinese]
Improved lobster eye lens based on Schmidt geometry
Ouyang Mingzhao, Zhu Wanbin, Fu Yuegang, Gao Tianyuan, Dong Keyan, Cui Chengkun, and Jiang Sulun
The lobster eye optics is the key technology that could achieve high energy ray imaging with a large field of view. The focusing principle of the lobster lens was explained in the viewpoint of optical imaging. The improved lobster eye lens prototype which was based on the Schmidt geometry was made, and the testing of tThe lobster eye optics is the key technology that could achieve high energy ray imaging with a large field of view. The focusing principle of the lobster lens was explained in the viewpoint of optical imaging. The improved lobster eye lens prototype which was based on the Schmidt geometry was made, and the testing of this system within visible light was finished. The reflection working surfaces of this lobster lens prototype were made of polished aluminum plates with 300 μm thickness. And the reflectors were arranged into fan shape; the whole lobster eye lens prototype was completely spherical symmetric structure. The angle 27.6′ between reflectors were generated by the special wedge plates. The focal length of the prototype is 65 mm and center angle is 17.48°×17.48°. The imaging ability of the system on every direction had much the same effect. It can meet the required of the large field detection task in space..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3610 (2015)
[in Chinese]
Surface profile measuring system based on fringe projection and sinusoidal phase modulation
Feng Fan, Duan Fajie, Bo En, Lv Changrong, Fu Xiao, and Huang Tingting
A fiber-optic interferometer based on fringe projection and sinusoidal phase modulation(SPM)for three-dimensional surface profile measurement was presented. It made use of Young’s double pinhole interference principle to achieve fringe projection. And sinusoidal phase modulation was accomplished by driving piezoelectriA fiber-optic interferometer based on fringe projection and sinusoidal phase modulation(SPM)for three-dimensional surface profile measurement was presented. It made use of Young’s double pinhole interference principle to achieve fringe projection. And sinusoidal phase modulation was accomplished by driving piezoelectric transducer using a cosine voltage single. To eliminate the external disturbances such as mechanical vibration and temperature fluctuation, a phase control system was proposed by detecting the phase drift and giving real-time compensation. The phase error was reduced to 6.8 mrad after compensating. A high phase stability of the interference fringe can be achieved. By measuring the surface profile of a glass plate for two times over an interval of 10 min, the repeatability is about 0.05 wave. Experimental results show that the proposed interferometer can be used for surface profile measurement with a high precision..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3762 (2015)
Configuration optimization of the differential filter in spatial filtering velocimeter
He Xin, Long Xingwu, Zhou Jian, and Nie Xiaoming
The pedestal components in output signals of spatial filtering velocimeter can be completely eliminated by differential method theoretically. However, because of varying amount of radiation energy incident onto the photodetector, some pedestal components still occur in the output signals, making it difficult to pick upThe pedestal components in output signals of spatial filtering velocimeter can be completely eliminated by differential method theoretically. However, because of varying amount of radiation energy incident onto the photodetector, some pedestal components still occur in the output signals, making it difficult to pick up desired signals, especially signals having very low frequencies close to zero. To remove the pedestal components in output of differential filters, the configuration of a COMS-type differential spatial filter in spatial filtering velocimeter was optimized. Every possible configuration of a differential filter was listed, and several typical configurations were chosen to analyze in detail by carrying out experiments. The quality of the output signals were analyzed in the aspects of power spectrum and signal-to-noise ratio under the condition of uniformed and non-uniformed illumination respectively. By comparison of quality of output signal from these several typical spatial filters, a most suitable configuration was obtained. This optimized configuration can noticeably eliminate the pedestal components in output signals..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3769 (2015)
Calibration method of space vector of beam for point laser sensor
Bi Chao, Liu Jingliang, Liu Fei, Lv Laipeng, and Lei Wenming
For the purpose of scanning and measuring 3D surfaces efficiently, a non-contact optical coordinate measuring system was established by installing a point laser sensor on the mobile terminal of Z axis of a CMM through a probe head. As a result of converting one dimensional distance values of the laser sensor to three dFor the purpose of scanning and measuring 3D surfaces efficiently, a non-contact optical coordinate measuring system was established by installing a point laser sensor on the mobile terminal of Z axis of a CMM through a probe head. As a result of converting one dimensional distance values of the laser sensor to three dimensional coordinates of the measuring points on the surface, a calibration method of the space vector of laser beam based on a spherical surface was proposed. In the calibration procedure, the trajectory of the laser sensor can be completed by controlling the movement of X, Y and Z axes of the CMM and several measuring points on the spherical surface can be collected by the sensor, in which the outputs of the grating rulers and the sensor were all recorded. Based on the above and the constraint equation of the spherical surface, a set of over-determined nonlinear equations was set up and the matrix least square method was used to solve the unit direction vector of the laser beam. Finally, a sphere with known diameter was measured by the optical coordinate measuring system at 10 different directions. Through calculation, the measuring errors are all smaller than 0.05 mm, which manifests the effectiveness of the calibration method proposed in the paper and lays the foundation of measuring spatial free surfaces rapidly and accurately..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3775 (2015)
Research on relative movement model of two satellites in space-based surveillance
Wang Weibing, Wang Rui, Jiang Zhenhua, Wang Tingfeng, and Guo Jin
Relative movement model of two satellites was mainly researched in space-based surveillance by geometry principle and vector calculation tool. On one hand, satellite orbit can be described clearly using a kind of producing rule of satellite orbit that is different of orbit elements and solving mechanics equation. On thRelative movement model of two satellites was mainly researched in space-based surveillance by geometry principle and vector calculation tool. On one hand, satellite orbit can be described clearly using a kind of producing rule of satellite orbit that is different of orbit elements and solving mechanics equation. On the other hand, relative directions of two satellites in the movement are researched by combining opto-electrical tracking system. Corresponding results of satellite orbit, relative distance, azimuth angle, pitching angle, azimuth angle velocity and pitching angle velocity were achieved after computing relative movement of two sun synchronous orbit satellites on different planes and two geosynchronous orbit satellites on the same planes. Analysis results show that this method is reasonable and provides qualitative and semi-quantitative reference for some physics question and key technologies in space-based surveillance such as design of satellite orbit, selection of work region, design of surveillance system and acquisition tracking and pointing control system..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3782 (2015)
Engineering calculation method of strap-down seeker disturbance rejection rate index
Yan Qintao, Xia Qunli, Qi Zaikang, and Lu Tianyu
In order to calculate the engineeized disturbance rejection rate(DRR) amplitude index accurately, the terminal guidance loop was introduced into the model of disturbance rejection rate parasitic loop. For the influence of the positive feedback disturbance rejection rate amplitude under the six common error models, a caIn order to calculate the engineeized disturbance rejection rate(DRR) amplitude index accurately, the terminal guidance loop was introduced into the model of disturbance rejection rate parasitic loop. For the influence of the positive feedback disturbance rejection rate amplitude under the six common error models, a calculation method of terminal guidance time remaining used for working in the guidance loop was presented. These were classified to three types for the constant target maneuver and initial angle error, random target maneuver, glint noise and faded and receiver noise, the relationship of relative speed ratio, the disturbance rejection rate amplitude and dimensionless miss distance was obtained, and the disturbance rejection rate amplitude index was estimated by the overall judgment of the miss distance value time, margin limits, miss distance change trend and practical value, which provide references for engineering application..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3788 (2015)
Line of sight angular rate estimation of semi-strapdown seeker electromechanical platform observer
Zhang Yue, and Chu Hairong
In order to estimate the semi-strapdown seeker line of sight(LOS) angular rate accurately, the Kalman observer using for estimating frame angular rate was researched. Firstly, according to the principle of semi-strapdown seeker tracking, mathematical model of Kalman observer for the state feedback was established. SecoIn order to estimate the semi-strapdown seeker line of sight(LOS) angular rate accurately, the Kalman observer using for estimating frame angular rate was researched. Firstly, according to the principle of semi-strapdown seeker tracking, mathematical model of Kalman observer for the state feedback was established. Secondly, based on the characteristics of the encoder error, the optimal estimation theory was used to calculate and analyze the relationship among the estimation precision and the observer parameters. Furthermore, under the premise that guarantees the bandwidth of stabilized platform, the Kalman observers under two different sampling rates were designed. Finally, the digital simulation experiment was done, and the result shows that angular rate estimation precision is 0.098 9 (°)/s with 2 000 Hz sampling rate, better than 0.301 3 (°)/s which sampling rate is 200 Hz. Seeker bandwidth which under two kinds of sample rates is 59.6 rad/s, and the seeker disturbance rejection rate is 1.5%. Improve the seeker stabilization system sampling rate and matching with the corresponding control parameters, can effectively improve the reporting rate estimation precision..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3794 (2015)
Maximum power point tracking and controlling based on compound PSO
Ma Dazhong, Zhai Xiaojun, and Sun Qiuye
Compound MPPT algorithm based on particle swarm optimization was proposed for solving the problem of maximum power point tracking under non-uniform insolation condition. Compound PSO-MPPT control algorithm contained off line optimization and on line optimization. During the process of off line optimization, informationCompound MPPT algorithm based on particle swarm optimization was proposed for solving the problem of maximum power point tracking under non-uniform insolation condition. Compound PSO-MPPT control algorithm contained off line optimization and on line optimization. During the process of off line optimization, information exchange mechanism between adjacent particles was used which can increase convergence speed and the search capability for critical areas. Fitness fuzzy judgment method was used to decrease the influence of disturbance and shorten the time-consuming which on line particle swarm optimization was considered. Compound PSO-MPPT control algorithm combined off line optimization and on line optimization together and it made up the shortfall of each method. The compound PSO-MPPT can acquire the faster response speed and higher accuracy of maximum power point than traditional MPPT algorithm. The proposed algorithm is testified by Matlab simulations and can realize the maximum power point tracking under non-uniform insolation condition..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3801 (2015)
Testing technology of spectral radiance of infrared target
Yuan Liang, Zhan Chunlian, Li Yan, Lu Fei, Li Zhengqi, and Li Tao
Spectral radiance of infrared targets are widely used in weapon photoelectric search, track and identify targets. Based on infrared radiate theory, the technologies of Fourier transform infrared spectroscopy(FTIR) and comparing with standard blackbody source were used to measure spectral radiance of infrared targets atSpectral radiance of infrared targets are widely used in weapon photoelectric search, track and identify targets. Based on infrared radiate theory, the technologies of Fourier transform infrared spectroscopy(FTIR) and comparing with standard blackbody source were used to measure spectral radiance of infrared targets at the same temperature and wavelength. The spectral radiance measurement system of infrared targets was also built. According to the results, it is shown that the measurement error is±1% at 1 000 ℃, 3 000 ℃, 5 000 ℃, 7 000 ℃ temperature point and the measurement error is less than 0.1% at 5 000 ℃, 7 000 ℃ temperature point at the range of 2.5-14 μm. Some factors that affect the measurement accuracy of the infrared spectral radiance were analyzed and discussed. It is obtained that the measurement error is greater when the standard black body temperature is inconsistent with the infrared target temperature; the measurement deviation is ±0.5% with InSb and MCT detector respectively at the range of 3.0-5.4 μm..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3807 (2015)
Calibration of absolute spectral responsivity at 1 064 nm of transfer detector against cryogenic radiometer
Pang Weiwei, Zheng Xiaobing, Li Jianjun, Shi Xueshun, Wu Haoyu, Xia Maopeng, Gao Dongyang, Shi Jianmin, Qi Tao, and Kang Qing
The significant uncertainty of absolute spectral responsivity of Standard Transfer Detector in infrared band is difficult to solve, the main factor is measure uncertainty of window transmittance, which is introduced by the state reproduction of Brewster Window. The calibration process and results of Standard Transfer TThe significant uncertainty of absolute spectral responsivity of Standard Transfer Detector in infrared band is difficult to solve, the main factor is measure uncertainty of window transmittance, which is introduced by the state reproduction of Brewster Window. The calibration process and results of Standard Transfer Trap Detector against a Cryogenic Radiometer at 1 064 nm were presented. The novel calibration structure, called Y calibration light path, could effectively eliminate the uncertainty caused by the window reflection loss inside the Cryogenic Radiometer. During the process, the linearity, spatial uniformity, polarization sensitivity and stability of the trap detector at 1 064 nm were measured. It is proved that the Standard Transfer Trap Detector shows a good performance with the uncertainty of absolute responsivity less than 0.023%. The repeatability experimental results show that Y calibration light path reconstruction of cryogenic radiometer is feasible..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3812 (2015)
[in Chinese]
Thermal cycle characteristic of InSb focal plane array detector
Wang Yang, Lu Xing, Meng Chao, Liu Junming, Kuang Yongbian, Meng Qingduan, Zhu Xubo, and Si Junjie
The cooled InSb infrared focal plane array(IRFPA) detectors should work in the temperature as low as 80 K. As a result, detectors are commonly subjected to thousands of thermal cycle from 80 K to room temperature(300 K) in the entire life cycle. Thermal cycle characteristic of the InSb IRFPA detector was studied. The FThe cooled InSb infrared focal plane array(IRFPA) detectors should work in the temperature as low as 80 K. As a result, detectors are commonly subjected to thousands of thermal cycle from 80 K to room temperature(300 K) in the entire life cycle. Thermal cycle characteristic of the InSb IRFPA detector was studied. The FPA photoelectric parameter, Dewar heat load and J-T cooling characteristics were analyzed. The results indicated that the maximal fluctuation of the detectivity was 5.5%, the maximal fluctuation of the responsivity was 4.8%, and the number of dead pixels did not increase. The experimental results exhibited that the detectors could undergo at least 2 000 thermal cycles, which provides reference for the research and improvement of detector fabrication..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3701 (2015)
Characterization of power spectral density of optical surface
Zhang Lei, Cheng Xinbin, Zhang Jinlong, and Wang Zhanshan
Using the Si substrate and the HfO2 single layer as the examples, the power spectral density (PSD) of the optical surface was calculated and characterized. First, the method that calculates the 1D power spectral density(PSD1D), 2D power spectral density(PSD2D) and isotropic power spectral density (PSDISO) was introduceUsing the Si substrate and the HfO2 single layer as the examples, the power spectral density (PSD) of the optical surface was calculated and characterized. First, the method that calculates the 1D power spectral density(PSD1D), 2D power spectral density(PSD2D) and isotropic power spectral density (PSDISO) was introduced. Then, the surface morphologies of the Si substrate and the HfO2 single layer were measured using atomic force microscopy with four scan areas, for example, 1 μm×1 μm, 5 μm×5 μm, 10 μm×10 μm, 20 μm×20 μm. Using a MATLAB program, the PSDISOs of the different scan area were calculated. And the PSDISO-Combined over a larger spatial frequency range was given using the geometric mean of these PSDISOs. The result shows that the PSDISO-Combined of Si substrate before and after HfO2 coating were similar for the low spatial frequency region but quite different for the middle and high frequency region. The poly-crystallized microstructure of the HfO2 coating is the main reason for the observed PSD difference between the Si substrate and the HfO2 coating. The σISO and σSTD were calculated and compared. The results are quite similar, which proves the correctness of the proposed method for the PSD calculation..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3707 (2015)
PbS photoconductive detector performance and reversibility in hygrothermal environment
Chen Fengjin, Si Junjie, and Shi Zhengfeng
New requirements on the reliability of the detector are put forward for the application of infrared detector in some special environment. In order to study the effect of hygrothermal environment on PbS detector performance, the PbS films had been prepared by CMD, surface morphology of the PbS films were showed, performNew requirements on the reliability of the detector are put forward for the application of infrared detector in some special environment. In order to study the effect of hygrothermal environment on PbS detector performance, the PbS films had been prepared by CMD, surface morphology of the PbS films were showed, performance and experiment between dry and hygrothermal environment were specified. The influence of Rd, Vs, Vn and D* between dry and hygrothermal environment were analyzed. The Rd of PbS photoconductive detectors had been incresed in hygrothermal environment and decresed in dry environment. The varieties of Rd was reversible between dry and hygrothermal environment, for the resistance of the PbS particles R0 and ΔR that had produced from the absorption of H2O in hygrothermal environment were constituted an equivalent series resistance, and ΔR changed with PbS detector in dry and hygrothermal environment, to form a kind of similar to the adjustable state variable resistance. The trend of Vn variety between dry and hygrothermal environment is same to that of the Rd, and on the opposition that of the D*..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3713 (2015)
Photorefractive properties of Ce:Fe:LiNbO3 crystals
Zhang Xin, Xu Zhaopeng, Lu Haitao, Tong Jianqiang, Gao Jie, and Wang Xiaojun
Ce:Fe:LiNbO3 crystals were processed with oxidized and reduced method. The crystal composition and defect structure were analyzed by the Ultraviolet(UV)-Visible(Vis) absorption and Infrared(IR) transmission spectroscopy. The photo-damage resistance ability of the samples was observed by straightly observing the transmiCe:Fe:LiNbO3 crystals were processed with oxidized and reduced method. The crystal composition and defect structure were analyzed by the Ultraviolet(UV)-Visible(Vis) absorption and Infrared(IR) transmission spectroscopy. The photo-damage resistance ability of the samples was observed by straightly observing the transmission facula distortion method. The results show that the photo-damage resistance ability of sample with growth state is essentially one magnitude higher than one with reduced state，and photo-damage resistance ability of sample with oxidation state is two magnitudes higher than one with reduced state. The photorefractive properties of the samples are experimentally studied by using the two-wave coupling method. The results of the two-wave coupling experiments show that from oxidation state to growth state to reduction state of the samples，the diffraction efficiency decrease but the response time is shorten and the photorefractive sensitivity increase while the dynamic range decrease slowly..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3718 (2015)
Effects of oxidational annealing on properties of VO2 thin films
Xu Kai, Lu Yuan, Ling Yongshun, and Qiao Ya
VO2 thin films were prepared by DC magnetron sputtering combined with oxidational annealed on Si substrate. SEM, XRD and XPS were employed to study the section, crystal composition, and valence of VO2 thin films from various aspects, and the infrared transmission properties was analyzed by FTIR. The results of analysisVO2 thin films were prepared by DC magnetron sputtering combined with oxidational annealed on Si substrate. SEM, XRD and XPS were employed to study the section, crystal composition, and valence of VO2 thin films from various aspects, and the infrared transmission properties was analyzed by FTIR. The results of analysis show that, a better crystal orientation of monoclinic rutile structure VO2 (011) crystal can be prepared through the method of DC magnetron sputtering combined with oxidational annealing, and the oxidational annealing is beneficial to the growing of VO2 grain and compactness of thin films. The VO2 thin films possesse a obvious phase transition properties, the transition temperature is 60.5 ℃, and the range of the change of infrared transmission rate at 3-5 μm and 8-12 μm has reached to 99.5%. The VO2 thin films have achieved the function of switch in infrared transmission, which can be an ideal material for the research in protecting infrared detector of laser attacking, and provides references for further in-depth study on oxidational annealing..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3723 (2015)
[in Chinese]
Stress sensing system based on laser speckle
He Fengtao, Cao Jinfeng, Wang Xiaolin, Zhu Yuhan, Zuo Bo, and Wang Jing
The sensing technology based on laser speckle has become one of research hotspots in the field of optical sensing to measure the stress, vibration, distance, speed and flow rate, owing to its significant advantages in simplicity and high precision. A set of stress sensing system based on laser speckle was designed in tThe sensing technology based on laser speckle has become one of research hotspots in the field of optical sensing to measure the stress, vibration, distance, speed and flow rate, owing to its significant advantages in simplicity and high precision. A set of stress sensing system based on laser speckle was designed in this paper. The wavelength of 405 nm laser was used as the light source in the system. The voice coil motor was used to vibrate multimode fiber, and CCD image sensor acquisition system was applied to image for polishing glass surface. MATLAB software was used to analyze the collected speckle images, calculating the contrast, fitting the curve of the speckle contrast. The results show that speckle contrast changes reflect the stress variation in the multimode fiber. Through the multimode fiber stress changes can be judged whether there is an intruder, anti-theft function is realized..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3729 (2015)
Improved layer peeling algorithm to realize FBG non-uniform strain sense demodulation
Shen Xiaoyan, Zhang Liangyue, Sun Jie, Hu Jiacheng, and Li Dongsheng
Layer peeling algorithm is a common method of fiber Bragg grating(FBG) parameter reconstruction, which can be used to demodulate the inhomogeneous strain applying on FBG. The study found that conventional layer peeling algorithm cannot figure out the exact value of complex coupling coefficient, to increase the non-unifLayer peeling algorithm is a common method of fiber Bragg grating(FBG) parameter reconstruction, which can be used to demodulate the inhomogeneous strain applying on FBG. The study found that conventional layer peeling algorithm cannot figure out the exact value of complex coupling coefficient, to increase the non-uniform strain demodulation precision, a improved layer peeling algorithm called complex coupling coefficient amplitude correction method was proposed. The improved method retained the phase of coupling coefficient, corrected the amplitude of coupling coefficient, and used the modified complex coupling coefficient on layer peeling calculation of the reflection spectrum. The following 4 reflection spectrums of FBG were obtained by the transfer matrix simulating method: without strain, strain increasing linearly, strain decreasing linearly and strain of quadratic curve, the strain results were calculated by both the conventional method and the improved method. The experiment shows that the strain results of the improved method are consistent with the input strain; With different theoretical strains, mean of the largest error of improved method is about 1/5 of conventional method, the mean of root mean square error is about 1/7 of the conventional one, the error is obviously much smaller..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3734 (2015)
Temperature characteristic of liquid-filled photonic crystal fibers with nearly zero ultra-flattened dispersion
Lei Jingli, Yan Zuyong, Li Xiaoxiao, Liu Yanjun, Wu Gang, and Hou Shanglin
The effects of temperature on dispersion, mode effective area and nonlinearity of an ethanol-filled index-guiding hexagon photonic crystal fiber were investigated using the vectorial beam propagation method. The results indicate that temperature has a significant influence on dispersion at the wavelengths of flattened The effects of temperature on dispersion, mode effective area and nonlinearity of an ethanol-filled index-guiding hexagon photonic crystal fiber were investigated using the vectorial beam propagation method. The results indicate that temperature has a significant influence on dispersion at the wavelengths of flattened dispersion, the bandwidth of flattened dispersion increases with temperature increasing. At the short wavelengths of flattened dispersion, the temperature has greater influence on the dispersion and the dispersion becomes more flattened. The impact of temperature on the mode effective area and the nonlinearity is larger at long wavelengths than at short wavelengths of flattened dispersion. At a given wavelength of flattened dispersion, dispersion and nonlinearity increase with temperature increasing. The result provides theoretical reference for designing novel optical communication components or optical sensors..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3740 (2015)
Orbital angular momentum research of high order Bessel Gaussian beam in a slant atmosphere turbulence
Ke Xizheng, and Guo Xinlong
Atmospheric turbulence can cause random variations of the refractive index, resulting in a spatial inhomogeneity. When a high order Bessel Gaussian beam is propagating through the atmospheric turbulence, spatial inhomogeneity can bring about the change of photon wave function that causes the disperse of the orbital angAtmospheric turbulence can cause random variations of the refractive index, resulting in a spatial inhomogeneity. When a high order Bessel Gaussian beam is propagating through the atmospheric turbulence, spatial inhomogeneity can bring about the change of photon wave function that causes the disperse of the orbital angular momentum to form different photon states. Under the Rytov approximation, when the high order Bessel beam was propagating in a slant-path atmospheric turbulence, the weight of the spiral harmonic component of the beam energy was calculated. And then, the impact on the spiral spectrum of the beam propagating in the slant ways, caused by refractive index structure constant, the wavelength of the beam, the zenith, orbital angular momentum, the receiver aperture, spot size were discussed and compared and a series of concrete explanations were given. The research results show that with increasing refractive index structure constant and the zenith and with decreasing wavelength of the beam, the spectrum of the spiral harmonic main component reduces and the orbital angular momentum disperses more serious. The receiver aperture and spot size have little effect on the orbital angular momentum disperse..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3744 (2015)
Thermal design and analysis for fiber optic gyroscope combination
Liu Ying, Fan Yongqing, and Xu Jintao
In order to meet the requirements of environmental temperature, complete quickly and reliably the design scheme of FOG combination, the thermal design and analysis of FOG combination were carried out. The combination model and finite element model were established, the boundary conditions and constraints conditions werIn order to meet the requirements of environmental temperature, complete quickly and reliably the design scheme of FOG combination, the thermal design and analysis of FOG combination were carried out. The combination model and finite element model were established, the boundary conditions and constraints conditions were set, the temperature and the reliability of the key components and assemblies of the combination FOG were analyzed in entire temperature cycles. Finally, the maximum temperature of DSP was reduced by 10 ℃, the maximum temperature of DC/DC power modules was from the original 90 ℃ down to 70 ℃, the all critical components and assemblies were working within their rated temperature range through the way of thermal design, the uniformity of fiber optic gyroscope combination of internal temperature field was improved, from the original 30 ℃ down to 10 ℃, a basis was provided to determine the design of scheme..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3750 (2015)
Influence of square-wave modulation distortion on closed-loop fiber optic gyroscope and its elimination
Liu Shiwei, Wang Jiakou, Hu Yibin, and Zhuang Qiren
Square-wave modulation with various distortion will influence the outputs of the digital closed-loop Fiber Optic Gyroscope(FOG) when measuring angular velocity. Based on Fourier series, square-wave modulation models and signal demodulation models for closed-loop FOG including distortion noise were built in this paper. Square-wave modulation with various distortion will influence the outputs of the digital closed-loop Fiber Optic Gyroscope(FOG) when measuring angular velocity. Based on Fourier series, square-wave modulation models and signal demodulation models for closed-loop FOG including distortion noise were built in this paper. Simulation studies were analyzed for the output errors caused by different modulation distortion signals. A new demodulation method of bipolar return to zero pulse of square-wave for the elimination of errors in output signals of FOG was proposed. The simulation results show that the distortions, including phase distortion, pulse width distortion, harmonic distortion and noise comb pulse, have a great influence on outputs of FOG when using conventional demodulation methods of square-wave. Measuring the relative errors of angular velocity is up to 1%. But the errors are effectively eliminated when using bipolar return to zero pulse of square-wave demodulation, and are one order of magnitude lower than the errors in conventional demodulation methods. The simulation proves that the demodulation method of bipolar return to zero pulse of square-wave is very meaningful for improving measurement accuracy and stability of the digital closed-loop FOG..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3755 (2015)
[in Chinese]
Design and research of secondary microprism in dense matrix type concentrating photovoltaic module
Yang Guanghui, Liu Youqiang, Wang Yumin, Guo Limin, Chen Bingzhen, and Wang Zhiyong
For the problems that secondary concentrators structure is complex, process is difficult, and cost is high, considering the actual engineering application, design of secondary microprism for dense matrix type concentrating photovoltaic module was presented. The 3-D model of this design was established by Solidworks andFor the problems that secondary concentrators structure is complex, process is difficult, and cost is high, considering the actual engineering application, design of secondary microprism for dense matrix type concentrating photovoltaic module was presented. The 3-D model of this design was established by Solidworks and important parameters such as inclination angle and component height get optimized using Zemax. The results show that the combination has the highest energy when secondary microprisms height is 5 mm, upper side lengths is 7 mm and working face inclination is 67.38°. The energy of solar cell surface can reach 2.466 9 W, increasing by 31% compared with that of without secondary microprisms. It shows that the secondary microprism is very important in dense matrix type concentrating photovoltaic module..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3645 (2015)
Design and buckling analysis of TMT tertiary mirror cell assembly flexure structure
Guo Peng, Zhang Jingxu, Yang Fei, Zhao Hongchao, and Wang Fuguo
Thirty Meter Telescope′s tertiary mirror is an elliptical ceramic glass reflector whose major axis is 3.594 m and minor axis is 2.536 m. Flexure structure was widely used in the mirror′s support structure to release all the other degree of freedom except those along the support direction. The design decoupled the axialThirty Meter Telescope′s tertiary mirror is an elliptical ceramic glass reflector whose major axis is 3.594 m and minor axis is 2.536 m. Flexure structure was widely used in the mirror′s support structure to release all the other degree of freedom except those along the support direction. The design decoupled the axial and lateral support and reduce the thermal stress due to the material mismatch. The higher compliance would benefit the telescope′s mirror surface under distortion, but the buckling criteria load would decrease correspondingly, either. So the limit load of each flexure structure should be calculated as the design input. And the buckling safety factor SFBuckling was analyzed for each part under the limit loads. Eigenvalue buckling analysisand nonlinear buckling analysis were both taken and compared. Based on the analysis results, the design were optimized iteratively to achieve balanced values of compliance for all the flexure. The mirror surface error under thermal distortion met the design requirements..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3650 (2015)
Design of infrared and visible optical diagnostic system with wide field for EAST Tokamak plasma
Yang Xiaofei, and Gan Kaifu
A middle infrared and visible optical diagnostic system was designed for EAST Tokamak plasma. Through adopting innovate optical structure, the system satisfied the imaging requirements, and avoided the radiation and stain at the same time. And through using dichroic beam split mode, the middle infrared and visible pathA middle infrared and visible optical diagnostic system was designed for EAST Tokamak plasma. Through adopting innovate optical structure, the system satisfied the imaging requirements, and avoided the radiation and stain at the same time. And through using dichroic beam split mode, the middle infrared and visible path can image with common aperture and filed, which improved the observation efficiency. At last the wide-angle infrared and visible plasma imaging system was designed, with 3 mm aperture diameter and 58°×47° field of view. After alignment, the optical performance was tested, and the results show that all of the indexes satisfy the requirement the system. Through the imaging experiment for the discharge process in the EAST tokamak, the middle infrared and visible path of the system can image with wide-angle and high contrast synchronously..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3656 (2015)
Integrated optimization design of truss-supporting structure for space camera
Yuan Jian, Sha We, Chen Changzheng, Zhang Xingxiang, and Ren Jianyue
Truss-supporting structure was widely used among TMA space camera of large or middle size, and how to improve its dynamics characters was the key to the study of cameras alike. As to the design problem of truss structure, bring forward a method of ascertaining the position of the trusses via integrated optimization, stTruss-supporting structure was widely used among TMA space camera of large or middle size, and how to improve its dynamics characters was the key to the study of cameras alike. As to the design problem of truss structure, bring forward a method of ascertaining the position of the trusses via integrated optimization, study the influence of position variables of the trusses on dynamics characters via designed of experiment, analysed the characteristic of its resolution space. In order to realize whole-space optimized designed of truss, used multi-island genetic algorithm to find the bested resolution, with the objective of improving the 1st-frequency. Used FEM method, find the 1st-frequency of optimized design was 107.72 Hz, which was 29% improved compared with original design(83.45 Hz). The integrated optimization modeling and the analysis method in this study offer a new way for the design of truss structure..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3661 (2015)
Optical design of new two-mirror catadioptric flat-field anastigmat telescope
Sun Wen, Hu Jianjun, Zhao Zhicheng, Chen Xinhua, Han Lin, and Shen Weimin
Small satellites had the advantages of low-cost and being suitable for flexible tactics application. But it was a challenge to realize optical remote sensing in meter or sub meter level based on satellite platform which weight dozens of kilograms. A new two-mirror catadioptric system which consisted of two aspheric mirSmall satellites had the advantages of low-cost and being suitable for flexible tactics application. But it was a challenge to realize optical remote sensing in meter or sub meter level based on satellite platform which weight dozens of kilograms. A new two-mirror catadioptric system which consisted of two aspheric mirrors and a negative focal power group with three lens was proposed. This system was coaxial as traditional two-mirror system. Then the structure was compact and installation would be easy. At the same time, the system had flat filed and was anastigmatic as three-mirror system. At first, basic idea and structure of the new system were introduced, its primary aberration formula was derived, the means for correcting its aberrations including chromatic aberration was analyzed and presented, and thereby its initial structures were solved. Then, An example which had compact structure and was suitable for optical system on low-orbit high-resolution small satellite was designed and optimized. Its work band, full field of view, effective focal length and F-number were from 450 nm to 800 nm, 1.2毅, 3000 mm, F/10. Length of the optical system and the stop were 595 mm and 300 mm. Negative focal power lens group corrected chromatic aberration by itself, and three lens used same common glass. Imaging quality of the system was diffraction-limited..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3667 (2015)
Optical tracking platform based on umbrella multi-tier distributed structure
Qiao Yongming, Ma Caiwen, Jin Humin, Hao Wei, and Lv Tao
The basic features that should be possessed are detecting long-distance target, capturing rapid target and tracking multiple target for a high-performance optical warning system. It is the basic condition to achieve the whole airspace closure detection. Due to inherent structural defects, there are some problems in theThe basic features that should be possessed are detecting long-distance target, capturing rapid target and tracking multiple target for a high-performance optical warning system. It is the basic condition to achieve the whole airspace closure detection. Due to inherent structural defects, there are some problems in the application of early warning for traditional optical tracking platform. A new concept of structure called umbrella multi-tier distributed load structure was proposed that was fitted in photoelectric tracking platform applied in optical warning. Through the structural feature of the new type of tracking platform, combining with measurement-mode plan of multi-detector, optimizing control and information processing system, it aims to solve the problems effectively that restricts the performance for optical warning system, such as the small searching field-goal; single target tracking; the top blind of tracking. It will break the bottleneck of optical tracking device application in optical warning system..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3673 (2015)
Long type scanning mirror with flexible supporting
Zhang Lei, Ding Yalin, Xu Zhengping, Zhang Hongwen, Zhang Jian, and Guo Wancun
A scanning mirror with the material RB-SiC was designed based on the flexible support, which could operate in complex environment and the reflection mirror′s surface precision was enhanced. A lightweight design was conducted on the scanning mirror in the way of combining the triangular elements and quadrilateral elemenA scanning mirror with the material RB-SiC was designed based on the flexible support, which could operate in complex environment and the reflection mirror′s surface precision was enhanced. A lightweight design was conducted on the scanning mirror in the way of combining the triangular elements and quadrilateral elements on the back-open-architecture; The locations of supporting were optimized by analyzing the impaction of supporting span on the deformation of mirror. Meanwhile, the universal-flexible support structure was designed to eliminate stress during alignment process and alteration of environment. The finite element model of the scanning mirror component was established, and the surface precision could be 0.023λ according to the calculation; The mirror′s surface precision was measured by the ZyGo interferometer with the method of autocollimation after calculation, and the RMS was 0.029λ. The static and dynamic imaging tests were compared through the simulation of the infinite distance target, and the results show the image quality meets well. The imaging stability of the scanning mirror performs well after flight test of imaging the target on ground, the result shows that the photograph performs well..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3678 (2015)
Design of single aspheric lens used as beam lens
Qin Hua, Feng Dongtai, Zhang Shuang, Li Wenrui, and Wang Jingru
In order to obtain a single aspheric lens for beam shrinkage, based on the law of refraction in vector form and theoretical analyses of the refraction characteristics of an aspheric surface, a new method was presented for designing a single aspheric lens used as a beam expander or a beam compressor —the comprehensive lIn order to obtain a single aspheric lens for beam shrinkage, based on the law of refraction in vector form and theoretical analyses of the refraction characteristics of an aspheric surface, a new method was presented for designing a single aspheric lens used as a beam expander or a beam compressor —the comprehensive learning strategy particle swarm optimizer. A single aspheric beam-expanding lens was designed whose length is less than 170 mm and shrinkage rate is 14.16. The process of beam-shrinking or beam-expanding was simulated by using the ray tracing method. Simulation results show that a single aspheric lens can play the role of compressing beam or expanding beam, the comprehensive learning particle swarm algorithm can be used to design an aspheric lens used as compressing beam or expanding beam. A single aspheric beam-expanding（beam-compressing）lens can greatly simplify the beam expanding（beam compressing）system, and greatly improve the uniformity of output light from the expanding lens..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3684 (2015)
[in Chinese]
Study on real-time spectrum recovery system on a FPGA chip for Fourier transform infrared imaging spectrometer
Yin Shimin, Liang Yongbo, Zhu Jianming, Liang Jintao, and Chen Zhencheng
In view of the real-time data processing requirements of Fourier transform infrared imaging spectrometer, a real-time spectrum recovery system on a FPGA chip for the spectrometer was studied which integrates the functions of interferogram nonuniformity correction, spectrum recovery and spectral radiation calibration. TIn view of the real-time data processing requirements of Fourier transform infrared imaging spectrometer, a real-time spectrum recovery system on a FPGA chip for the spectrometer was studied which integrates the functions of interferogram nonuniformity correction, spectrum recovery and spectral radiation calibration. The system has made a standardized design of the input signals. It can be run in line way, output target's spectrum in real-time and be embedded in the real-time data processing system for various types of infrared/visible Fourier transform imaging spectrometer which has some specialties such as small volume, fast computing speed, good stability, high reliability and easy to upgrade. The system can establish a good technical foundation for the real-time target recognition based on the spectral characteristics..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3580 (2015)
Ballistic missile tracking performance in boost phase based on dual infrared early warning satellites
Zhong Yu, Wu Xiaoyan, Huang Shucai, Wu Jianfeng, Li Chengjing, and Tang Yidong
To study the ballistic missile tracking performance in boost phase based on infrared early warning satellites system, Posterior Cramer-Rao Lower Bound (PCRLB) was proposed as a measurement index. After modeling ballistic target motion by 8-state gravity turn model and locating target position by dual satellites' beTo study the ballistic missile tracking performance in boost phase based on infrared early warning satellites system, Posterior Cramer-Rao Lower Bound (PCRLB) was proposed as a measurement index. After modeling ballistic target motion by 8-state gravity turn model and locating target position by dual satellites' bearing-only passive localization, PCRLB was used to evaluate the effects of factors, including target motion model accuracy, measurement accuracy, sampling period, detection probability and false alarm number conditioned by measurement origin uncertainty, on tracking timeliness and accuracy. One simulation example showed the extent and rules of said factors on position and tracking performance of velocity. It can contribute to the anti-ballistic missile operation by early warning satellite, the relationship modeling between tactical and technical indices and the optimal design of satellite-based infrared detector..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3587 (2015)
Effects of mixing duct geometric parameters on flow dynamics and infrared radiation characteristics for IR suppressor
Chen Geng, Shan Yong, Tan Xiaoming, and Zhang Jingzhou
Based on CFD/IR numerical simulations, the effects of aspect ratio as well as relative space out of mixing duct on helicopter aerodynamics and infrared radiation characteristics were studied systematically. Conclusions can be drawn as follows according to the present simulation conditions: In comparison with IR suppresBased on CFD/IR numerical simulations, the effects of aspect ratio as well as relative space out of mixing duct on helicopter aerodynamics and infrared radiation characteristics were studied systematically. Conclusions can be drawn as follows according to the present simulation conditions: In comparison with IR suppressor with oval outlet, suppressor with rectangular outlet owns a stronger ejecting capacity, and its 3-5 μm infrared radiation intensity is relatively lower, which is exemplified by the fact that the maximum infrared radiation intensity decreased by 10.7％ by changing the shape of mixing duct outlet from oval to rectangle. With the aspect ratio of mixing duct exit rising from 2.2 to 4.6, the pumping ratios of the IR suppressors come to increase, but the total pressure recovery coefficients of those suppressors only change slightly. It can be the instrument of enhancing the pumping capacity when the relative space out of mixing duct is extended, which hardly contributes to greater pressure loss on the other hand. Whether the aspect ratio of the mixing duct exit is increased or relative space out of mixing duct is extended, the infrared radiation intensity(3-5 μm) for IR suppressors is going to decrease gradually in both horizontal and vertical planes..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3597 (2015)
Simulation of dynamic infrared sea scene in mid band
Wang Yan, Xie Xiaofang, Sun Haiwen, Yang Jian, and Xu Cong′an
The dynamic simulation of IR sea scene with large area is an important part of simulation of 3D sea battlefield environment, which has great application value. Using the GPU shader technique, a simulation method of dynamic infrared sea scene was presented, which introduced texture of normal map, and achieved a lifelikeThe dynamic simulation of IR sea scene with large area is an important part of simulation of 3D sea battlefield environment, which has great application value. Using the GPU shader technique, a simulation method of dynamic infrared sea scene was presented, which introduced texture of normal map, and achieved a lifelike sea infrared real-time simulation. Constructing the infrared sea module with rectangular plane, and the radiation character, radiation intensity and direction of sea surface with normal map in GPU shader were calculated. The dynamic wave simulational shader algorithm based on texture operation was used to realize the dynamic change of normal of pixel. In order to improve the real-time rendering efficiency, view point based scheduling and view field detecting technique were proposed. The experiment shows that the rendering speed of infrared sea scene created by the method can achieve 80 frame/s, meets the requirement of real-time simulation, and can simulate the effect of facula on mid band sea surface..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3604 (2015)
[in Chinese]
Automatic alignment of multiplexed beams of excimer laser MOPA system based on crosshair array
Shao Bibo, Ma Lianying, Qian Hang, Wang Dahui, Zhao Xueqing, Zhang Yongsheng, Feng Gang, and Yi Aiping
In order to achieve precise multi-passes amplification on amplifiers and high pointing accuracy on target of laser beams, study on multiplexed beams automatic alignment of high efficiency excimer laser was described. Image-relaying structure with two cross-hairs, served as the near-field and the far-field references onIn order to achieve precise multi-passes amplification on amplifiers and high pointing accuracy on target of laser beams, study on multiplexed beams automatic alignment of high efficiency excimer laser was described. Image-relaying structure with two cross-hairs, served as the near-field and the far-field references on the input beam and output beam, was proposed. In this way, the problems of nonexistence of nature alignment reference and parallel automatic alignment of multiplexed beams were solved accordingly. In the end, laser automatic alignment system of the three beams with double paths in pre-amplifier II was set up, which validated the feasibility of this method. Meanwhile, joint experiment of automatic alignment system including imaging system and feedback control structure was accomplished..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3507 (2015)
Dual-wavelength eye-safe laser based on Nd:GYSGG/YVO4 intracavity stimulated Raman conversion
Wang Hui, Zhang Huifeng, and Guo Tao
A compact AO Q-switched dual-wavelength laser operated in 1.5 μm eye-safe region was demonstrated via stimulated Raman scatting of a-cut YVO4 crystal within an end-pumped dual-wavelength Nd:GYSGG laser cavity. The in-band pumping absorption peak and coefficient were measured to conduct efficient pumping, thus overcominA compact AO Q-switched dual-wavelength laser operated in 1.5 μm eye-safe region was demonstrated via stimulated Raman scatting of a-cut YVO4 crystal within an end-pumped dual-wavelength Nd:GYSGG laser cavity. The in-band pumping absorption peak and coefficient were measured to conduct efficient pumping, thus overcoming the drawback of short thermal focal length of Nd:GYSGG crystal and scaling up the eye-safe output. 1.44 W of simultaneous output at 1 497 and 1 516 nm was obtained under absorbed pump power of 17.1 W at the pulse repetition rate of 20 kHz, corresponding to a conversion efficiency of 8.4%. The 1 497 nm and 1 516 nm fractions are 0.55 and 0.89 W, respectively, measured after split by a prism. The beam quality factor M2 is 2.4 at the maximum output. Compared with 808-nm traditional pumping, both the laser output power and the beam quality are greatly improved..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3512 (2015)
Investigation of self-Q-switched ytterbium-doped double-clad fiber lasers based on Rayleigh scattering and stimulated Brillouin scattering
Huang Lin, and Wang Shumei
The rate equations of ytterbium-doped double-clad fiber lasers were solved by numerical simulation under principles of fiber interference loop and stimulated Brillouin scattering. The relationships between pulse repetition rate, pump power and couple ratio of the coupler which constructed the fiber interference loop weThe rate equations of ytterbium-doped double-clad fiber lasers were solved by numerical simulation under principles of fiber interference loop and stimulated Brillouin scattering. The relationships between pulse repetition rate, pump power and couple ratio of the coupler which constructed the fiber interference loop were obtained. The relationships between average output power, pulse energy, pump power and couple ratio were also obtained by exploiting the model based on photon balance. A self-Q-switched Yb3+-doped double-clad fiber laser was employed experimentally to test how the pump power affect average power, pulse energe and pulse repetition rate respectively. The results show that both average power and pulse repetition rate can be increased by increasing pump power, and the increase of pulse energy needs to choose appropriate couple ratio other than the increase of pump power. It also shows that the second-order Stokes pulse will be stimulated if the pump power is high enough..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3517 (2015)
Method of differential laser Doppler ship wake detection
Lu Zhenzhong, Wang Peinan, Liu Jifang, Sun Yanling, and Ma Lin
The optical method of differential laser Doppler for the ship wake detection was studied. The characteristics of the backscattering light for the bubble and turbulence were experimentally studied. The velocity of the ship wake field was obtained by the laser differential Doppler method, which is in coincidence with theThe optical method of differential laser Doppler for the ship wake detection was studied. The characteristics of the backscattering light for the bubble and turbulence were experimentally studied. The velocity of the ship wake field was obtained by the laser differential Doppler method, which is in coincidence with the actual value, and the relative error is less than 1.5%. The experimental results show that the angle between two coherent beams has obvious effects on the frequency shift. And the frequency shift increases as the angle increases. The frequency shift spectra for the bubble are characterized by a universal profile and at the low frequency end. The full width at half peak of the profile becomes larger as the field intensity increases, which can be seen as a criterion of the wake recognition..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3525 (2015)
Free space optical communication based on supercontinuum laser source
Huang Long, Feng Guoying, and Liao Yu
Supercontinuum laser source is an excellent candidate as signal carrier because of its wealth of bandwidth. Free space optical communication system based on supercontinuum laser source was designed and established. The conditions of supercontinuum generation and the out spectrum at different locations of laser beam spoSupercontinuum laser source is an excellent candidate as signal carrier because of its wealth of bandwidth. Free space optical communication system based on supercontinuum laser source was designed and established. The conditions of supercontinuum generation and the out spectrum at different locations of laser beam spot were discussed. The supercontinuum laser source was modulated by electro-optic modulator. And the feasibility of free space optical communication based on supercontinuum laser source which used electro-optic modulator was proved by comparing the input and output of digital square wave signals. Besides, the image signals collection and display were successfully demonstrated. Finally, the original signals were recovered by the shaping amplificaton of receiving end signals, the image signals transmission in the range of 4 m was successfully realized. According to the experiments mentioned above, supercontinuum laser source under the condition of the free space can realize transmission of wreless video signals..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3530 (2015)
Rapid calculation method for capture area of laser guided bomb
Zhang Daochi, Xia Qunli, He Xiaofu, and Liu Dawei
To achieve the rapid calculation of the laser guided bomb′s total capture area, based on the principles of capture target of laser seeker, taking the target point as center, the instant capture area model was established and the shape of instant capture area and its deciding factor were analyzed. On this basis, the calTo achieve the rapid calculation of the laser guided bomb′s total capture area, based on the principles of capture target of laser seeker, taking the target point as center, the instant capture area model was established and the shape of instant capture area and its deciding factor were analyzed. On this basis, the calculation method of total capture area of laser guided bomb was proposed. Secondly, under the assumption of flight path angle keeping constant, the total capture area′s theoretical expressions of guided bomb with gimbaled seeker or strapdown seeker were put forward. Finally, the results of total capture area of laser guided bomb guided by proportional navigation guidance and trajectory shaping guidance calculated through theoretical expression and computer simulation were contrasted. The results show that the expression′s result matches the simulation and the theoretical expression can be used on fast calculation of laser guided bomb′s total capture area..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3535 (2015)
Experimental study on the effect of the remaining absorbing layer on laser shock processing
Ye Yunxia, Zhao Shuyi, Xiong Song, and Gao Changda
Remaining absorbing layers have a significant influence on the shock effects of metal samples in laser shock processing(LSP). However, the influence laws are still pending. In this paper, the experiments of LSP were conducted with different materials as the absorbing layers. The influence of the thicknesses of the absoRemaining absorbing layers have a significant influence on the shock effects of metal samples in laser shock processing(LSP). However, the influence laws are still pending. In this paper, the experiments of LSP were conducted with different materials as the absorbing layers. The influence of the thicknesses of the absorbing layer was also studied. To guarantee that there were remaining absorbing layers on the target surface after shock, the laser parameters were carefully chosen. The influence laws of the remaining absorbing layers on the laser shock effect were researched by measuring the laser shock induced-pit sizes and the mechanical properties of the shocked zones. Furthermore, the shock wave signals on the back of the metal samples were tested by PVDF detector. Experimental results show that, the remaining absorbing layers can attenuate shock wave seriously. Therefore, the shock effects are weakened accordingly. Through the experimental and theoretical research, it can be found that there exist an ideal absorbing layer with "the optimal acoustic impedance", when the confinement layer and metal sample are determined. With the ideal absorbing layer, we can get the strongest shock effect. For achieving good results in LSP, the absorbing layer material should be carefully chosen according to theconfinement layer and metal sample. In the same time, the thickness of an absorbing layer should be controlled reasonably. The results of this paper can provide guidance for choosing the most appropriate absorbing layer for different metal samples in LSP..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3541 (2015)
Effects of oblique laser shock processing on rotary bending fatigue of aero-engine fan shaft
Shen Xiaojun, Wang Cheng, An Zhibin, Zhou Liucheng, Lai Zhilin, and Wang Guan
The circular bead of aero-engine fan shaft was obliquely shocked by laser shock processing(LSP). The shocking parameters were determined according to the analysis of the oblique laser shock model. After being obliquely laser shocked, the surface residual stress and micro-hardness of the aero-engine fan shaft were invesThe circular bead of aero-engine fan shaft was obliquely shocked by laser shock processing(LSP). The shocking parameters were determined according to the analysis of the oblique laser shock model. After being obliquely laser shocked, the surface residual stress and micro-hardness of the aero-engine fan shaft were investigated and analyzed. Besides, the rotary bending fatigue tests and fracture analysis were also conducted. The experimental results show that the micro-hardness of the fan shaft increased about 11% by laser shock processing, which modified the inhomogeneity of the surface residual stress, and the rotary bending fatigue life of fan shaft increased by 160% after LSP. The fracture analysis show that the location of fatigue initiation migrated to a inner place of materials and the crack growth speed of fan shaft reduced by LSP, which is necessary for improving the fatigue life..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3548 (2015)
Research on pulse characteristics of non-chain pulsed DF laser
Ruan Peng, Xie Jijiang, Pan Qikun, Wang Chunrui, Liu Chunling, and Chai Yuan
The effects of mixture gas ratio, gas pressure, charging voltage and output mirror reflectivity on laser pulse characteristics were studied. High energy was achieved when the ratio and output mirror reflectivity are 10∶1 and 30%, respectively. The energy can be increased by raising charging voltage under the normal gloThe effects of mixture gas ratio, gas pressure, charging voltage and output mirror reflectivity on laser pulse characteristics were studied. High energy was achieved when the ratio and output mirror reflectivity are 10∶1 and 30%, respectively. The energy can be increased by raising charging voltage under the normal glow discharge condition, and there exists an optimum gas pressure for each voltage to obtain the highest energy. As for laser pulse width, it can be shortened by increasing mixture ratio and total gas pressure, while stretched by increasing charging voltage and output mirror reflectivity. Taking both laser energy and pulse width, the variation trend of laser peak power is similar with the output energy on the whole, but the parameters of mixture gas and output mirror which make the energy or the peak power reaching maximum are different..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3554 (2015)
Microstructures and mechanical properties of laser deposition of TA15 titanium alloy with ultrasonic treatment
Wang Wei, Li Xinyu, Yang Guang, Qin Lanyun, and Ren Yuhang
In order to improve the mechanical property of laser deposition TA15 titanium alloy, the harmonic response analysis of the ANSYS finite element dynamic analysis was adopted, amplitude distribution and particle vibration of the bottom surface of the trapezoidal groove surface with ultrasound were simulated, and the expeIn order to improve the mechanical property of laser deposition TA15 titanium alloy, the harmonic response analysis of the ANSYS finite element dynamic analysis was adopted, amplitude distribution and particle vibration of the bottom surface of the trapezoidal groove surface with ultrasound were simulated, and the experiments were carried out to verify the simulation results. The comprehensive mechanics performance of laser deposition layers with ultrasound was researched by experiment test. The results show that, the points of the bottom surface of the trapezoidal groove with ultrasound presents periodic motion characteristics, and the maximum amplitude is about 1.6 μm, which is in a good agreement with simulation results. The laser deposition experiment with ultrasound was carried out, and the results show that the hardness of deposition repair region increases, tensile strength of deposition repair region rises by 3.2%, yield strength improves by 7.1%, and microstructures with ultrasonic field are observed that the α lamellas become shorter..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3559 (2015)
Calculation of elevation changing of Greenland′s ice sheet using GLAS laser altimeter
Ma Yue, Yang Fanlin, Wang Mingwei, Li Song, and Weng Yinkan
The spaceborne laser altimeter has the advantages of divergence angle of milli arc magnitude and no penetration effect on ice surface, which are suitable for monitoring the icesheet changing of polar region. Using elevation data of GLAS laser altimeter, the ice sheet changing of the region above 2 000 m of Greenland waThe spaceborne laser altimeter has the advantages of divergence angle of milli arc magnitude and no penetration effect on ice surface, which are suitable for monitoring the icesheet changing of polar region. Using elevation data of GLAS laser altimeter, the ice sheet changing of the region above 2 000 m of Greenland was obtained and analyzed through the crossing and repeat pairs over the time span of March 2003 to March 2009. The novel method was developed and applied to calculate crossing pairs in the entire Greenland where the latitudinal span was very large. After coarse error elimination and time series analysis, a positive elevation change rate of 3.80 cm/year, and a standard deviation of 0.91 cm were obtained, and change trends from the crossing and repeat pairs were agreed. The number of repeat pairs was much larger than that of cross pairs, approximately 4-15 times, while its spatial distribution was very non-uniform. The conclusion is that on elevation change monitoring in Greenland’s ice sheet,the crossing pairs is more fit for large zone, while the repeat ones suitable for small area..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3565 (2015)
Design of indoor laser radar navigation system
Shi Fengdong, Liu Wenhao, Wang Xin, Ding Juan, Shi Yijun, and Xiu Chunbo
With the rapid development of micro aerial vehicle technology and mobile robots technology, the requirements for indoor navigation technology are becoming higher and higher, but navigation presence is low and equipment is relatively complex in indoor navigation system. To address this problem, an indoor active navigatiWith the rapid development of micro aerial vehicle technology and mobile robots technology, the requirements for indoor navigation technology are becoming higher and higher, but navigation presence is low and equipment is relatively complex in indoor navigation system. To address this problem, an indoor active navigation method that combines laser radar positioning and geomagnetic sensors measurement was proposed. First, laser radar was used to scan the indoor environment, the map be constructed by collected data, the route be planed based on the destination information and the indoor environment information; and then the data which was obtained by laser radar continuously scanning environment was compared with the map data when the vehicle was traveling, the location was determined, direction of travel was obtained by geomagnetic sensor, whether the vehicle was on the right road was determined by the combination of position and direction of travel, the deviation will be corrected in time; last, whether arriving at designated location was determined by searching RFID landmarks. Simulation and experimental results show that the indoor laser radar navigation system is simple and the reliability is high, which meet the requirements of indoor navigation..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3570 (2015)
Smile effect of laser diode arrays measured by stylus scan method
Jia Guannan, Yao Shun, Pan Fei, Gao Xiangyu, and Wang Zhiyong
Traditional optical methods which are used to measure the Smile effect of laser diode arrays(LDA) have problems such as high precision optical system setting up, high operator quality requirements, vast and complex subsequent data processing, long measuring time and so on. In this paper, a new method that scanned the NTraditional optical methods which are used to measure the Smile effect of laser diode arrays(LDA) have problems such as high precision optical system setting up, high operator quality requirements, vast and complex subsequent data processing, long measuring time and so on. In this paper, a new method that scanned the N side of mounted LDA chips with the stylus of a mechanical contacting profiler was proposed to measure the Smile effect of LDA quickly. The measuring result was compared with the Smile effect measured by a traditional optical method. And the comparision indicates that their shapes are uniform and the difference is less than 1 micrometre. Using a profiler to measure the Smile effect of LDA takes little time less than 1 minute. The method can provide feedbacks quickly in chips bonding process to minimize the Smile effect, and can be easily integrated into high production lines to monitor the Smile effect of laser diode arrays in real time..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3576 (2015)
[in Chinese]
Effects of weakly ionized hypersonic flow on propagation of terahertz wave
Tian Yuan, Han Yiping, Niu Huaheng, and Lei Yuan
The plasma sheath produced in the progress of entry or reentry flight has attracted much attention as it would impact the propagation of electromagnetic wave. This plasma sheath is a group of weakly ionized gas in general and has the ability to influent the communication between aero craft and ground. Sometimes the exiThe plasma sheath produced in the progress of entry or reentry flight has attracted much attention as it would impact the propagation of electromagnetic wave. This plasma sheath is a group of weakly ionized gas in general and has the ability to influent the communication between aero craft and ground. Sometimes the existence of this plasma sheath even cloud cause the communication blackout which is not desirable. To improve this problem plenty of researches have done, some of the researches mentioned that raising the wave frequency could be one way. The development of intensive terahertz sources broke up the restrain of electromagnetic wave in microwave range, there comes out several researches on the interaction between terahertz wave and plasma. Computational fluid dynamics was used in numerical simulating of a thermodynamics and chemical nonequilibrium flow over the aero craft to calculate the electromagnetic characteristics of plasma layer. Four flight scenes and different incidence forms were taken to discuss the interaction between terahertz wave and plasma sheath. And the propagation of terahertz wave along with different paths was discussed. From the simulating results, terahertz wave is capable to transmit in the plasma sheath with high electron density when the flight height is lower..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3690 (2015)
Research on transmission capacity of THz for smoke
Wang Qichao, Wang Jiachun, Zhao Dapeng, Lin Zhidan, and Miao Lei
The extinction characteristic of graphite smoke at 337 μm was calculated on the basis of Mie scattering model. And the extinction characteristics of it at conventional infrared bands(3-5 μm, 8-12 μm) and representative wavelength of laser(1.06 μm) were calculated later. The results indicate that the mass extinction coeThe extinction characteristic of graphite smoke at 337 μm was calculated on the basis of Mie scattering model. And the extinction characteristics of it at conventional infrared bands(3-5 μm, 8-12 μm) and representative wavelength of laser(1.06 μm) were calculated later. The results indicate that the mass extinction coefficient(MEC) of the smoke at 337 μm is smaller by 1-2 orders of magnitude than that of other wavelengths or wavebands. Then, the transmission experiments about two kinds of smoke with different diameters of graphite particles were conducted respectively at those wavelengths and wavebands mentioned above. Finally, the MECs at 337 μm, 1.06 μm, 3-5 μm and 8-12 μm were deduced, and corresponding experimental results were contrasted. The MECs of two kinds of smoke at 337 μm are all less than 0.045 m2/g, and the values at other wavelengths or wavebands are further higher than it. The final results demonstrate that THz wave of 337 μm has stronger penetration capacity for smoke..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3696 (2015)
[in Chinese]
Stray light analysis and control for 50 BiN telescopes
Li Taoran, and Jiang Xiaojun
Stray light would reduce the signal to the noise ratio and photometric accuracy of astronomical observations. To ensure the high accuracy photometry of 50 BiN telescopes, the detailed stray light analysis was described. The accurate simulation model of 50 BiN telescopes was built in TracePro and the point source transmStray light would reduce the signal to the noise ratio and photometric accuracy of astronomical observations. To ensure the high accuracy photometry of 50 BiN telescopes, the detailed stray light analysis was described. The accurate simulation model of 50 BiN telescopes was built in TracePro and the point source transmittance value of the original optical system was calculated. The vanes inside the primary baffle were designed according to characteristic of the telescopes. Stray light uniformity was analyzed intensively, which played an important role in "differential photometry" system, stray light uniformity on focal plane was analyzed with MATLAB. These vanes were tested and verified to be effective with MATLAB and TracePro. The analysis results indicate that, at different incident angles, the stray light irradiance standard deviation on CCD focal plane is improved with the help of vanes. For the stray light sources located at the off-axis angle lager than 30°, the PSTs of the optical system are approximately 10-10 orders of magnitude. With the help of the vanes inside the primary baffle, the PSTs are declined 3-4 orders. These results show that vanes could improve the ability of stray light suppression and apply to the other telescopes in 50 cm binocular network as well as other astronomical telescopes..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3615 (2015)
Broadband optical concentration technology based on grating side-coupling
Lu Luyun, Wang Kaiwei, and Bai Jian
The technology of grating side-coupling is often applied in such fields as coupling of light of single wavelength or narrow waveband, pump of fiber laser, integration of optical waveguide, but its application for broadband coupling of visible spectrum is rarely studied. Sunlight can concentrate and output at the edge oThe technology of grating side-coupling is often applied in such fields as coupling of light of single wavelength or narrow waveband, pump of fiber laser, integration of optical waveguide, but its application for broadband coupling of visible spectrum is rarely studied. Sunlight can concentrate and output at the edge of waveguides by integrating sub-wavelength gratings with waveguides, making it a novel solar concentrator. In this paper, different grating structures with the Finite Difference Time Domain(FDTD) solution software were simulated to obtain the optimal structure design. Besides, the angle of light for the coupling-efficiency was also discussed. The result demonstrates that the structures mentioned above all feature good diffractive efficiencies in broadband wavelength, among which the blazing grating reaches the largest efficiency, namely 48.8%. This kind of sub-wavelength gratings feature integration of small size, which makes it promising in absorption of solar energy, such as lumination, photovoltaic cell, etc..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3621 (2015)
Kinematic analysis of a 3-DOF mini mechanism based on laser beam focusing by bracing the secondary mirror
Wang Shixiang, Guo Jin, Gan Xinji, and Wang Tingfeng
A 3-DOF parallel 3-PRS mechanism, which can realize one translational and two rotational motions and also can brace the secondary mirror used in laser beam focusing, was proposed. Traditional Euler angle for describing the motion of moving platform was adopted, and based on that, kinematic model of a 3-DOF mini mechaniA 3-DOF parallel 3-PRS mechanism, which can realize one translational and two rotational motions and also can brace the secondary mirror used in laser beam focusing, was proposed. Traditional Euler angle for describing the motion of moving platform was adopted, and based on that, kinematic model of a 3-DOF mini mechanism was built to analyze its direct and inverse kinematics performances including Jacobian matrix generation and solving the problem of accompanying motions. Furthermore, qualitative analysis of singularity and quantitative analysis of the reachable workspace of the mechanism were given. By combining ADAMS with MATLAB, the maximum and minimum motions of the moving platform including the motions of rotational x axis, rotational y axis and along z axis were approximate 15.167 1°, 13.319 4° and 9.954 1 mm respectively. The derived results strongly prove that a 3-DOF mini mechanism can fulfill the design requirement of the supporting structure of supporting the secondary mirror using laser beam focusing..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3627 (2015)
Far-field divergence for Gaussian beam under annular aperture diffraction
Wang Chao, Dong Keyan, Jiang Lun, and An Yan
The simple approximated analytic expression for the far-field divergence angle of Gaussian beam diffracted by an annular aperture was derived based on the Fraunhofer diffraction theory and by the approximate of the diffraction integration kernel function. For diffraction aperture with different diameters and obscuratioThe simple approximated analytic expression for the far-field divergence angle of Gaussian beam diffracted by an annular aperture was derived based on the Fraunhofer diffraction theory and by the approximate of the diffraction integration kernel function. For diffraction aperture with different diameters and obscuration ratios (OR), the analytic expression was compared by strict Fraunhofer diffraction expression, and the far-field divergences solved by these two expressions were nearly identical. The error was no more than 2.7%. Compared with the traditional method of getting the beam divergence by numerical integration, the troublesome integral was avoided, but a relative high precision was kept through this approximated formula. The analytic formula was effective on condition that the Gaussian beam waist diameter was more than or equal to 3.5 times the obscuration diameter, and less than or equal to the aperture diameter. In an actual engineering application, especially the space laser communication optical antenna with the characteristics of large-aperture and small-OR, the establishing conditions generally are satisfied..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3634 (2015)
Model wavefront-sensorless adaptive optics system based on eigenmodes of deformable mirror
Yang Huizhen1, Liu Rong, and Liu Qiang
Model wavefront-sensorless adaptive optics(AO) system has a great application potential because of its fast convergence and good correction. It is important for correction effect and convergence of AO system that how to generate basis functions and determine its number of order. Eigenmodes of deformable mirror(DM) wereModel wavefront-sensorless adaptive optics(AO) system has a great application potential because of its fast convergence and good correction. It is important for correction effect and convergence of AO system that how to generate basis functions and determine its number of order. Eigenmodes of deformable mirror(DM) were used as basis functions in this paper. AO simulation platforms were set up with a 32-element DM, a 88-element DM and a 127-element DM respectively and the correction effect and the convergence rate were investigated. Results show that AO systems can obtain the correction capability close to the ideal correction of DM, which indicates the correction capability of DM are utilized fully. Additionally, because the number of DM eigenmodes is equal to the number of DM actuators, it is not necessary to determine the required number of modes no matter how the strength of the aberrations is. The convergence speed of AO system only depends on the number of actuators of DM..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3639 (2015)
[in Chinese]
High sensitivity imaging based on DMD coding Hadamard Transform
Zhang Yi, Wang Yong, Yue Jiang, and Bai Lianfa
In order to enhance the image quality of the detector under the condition of Low Level Light(LLL) signal, a method of high sensitivity imaging based on Digital Micromirror Device(DMD) coding Hadamard Transform was proposed. On the basis of the assumptions that the noise of the detector and the signal as well as the noiIn order to enhance the image quality of the detector under the condition of Low Level Light(LLL) signal, a method of high sensitivity imaging based on Digital Micromirror Device(DMD) coding Hadamard Transform was proposed. On the basis of the assumptions that the noise of the detector and the signal as well as the noise measured each time are both independent, the influence of the noise to the SNR was analyzed in both HT coding imaging and classical imaging. The result was deduced that the improvement of SNR was related to the length n of coding templates in coding imaging, and the value was sqrt(n)/2 times of that in classic imaging. In order to reduce the encoding time of the image, the partitions coding method was applied. Results show that, compared with classical imaging modalities, the use of partitions coding Hadamard transform imaging significantly improves the signal to noise ratio of the image, while the coding time of high-resolution images is shortened..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3819 (2015)
Joint reconstruction algorithm for distributed compressed sensing
Cui Ping, and Ni Lin
Distributed compressed sensing is concerned with representing an ensemble of jointly sparse signals using as few linear measurements as possible. Joint reconstruction algorithm for distributed compressed perception was based on the idea of using one of the signals as side information, and then reconstruct other signalsDistributed compressed sensing is concerned with representing an ensemble of jointly sparse signals using as few linear measurements as possible. Joint reconstruction algorithm for distributed compressed perception was based on the idea of using one of the signals as side information, and then reconstruct other signals by the correlation between the side information and other signals. To resolve the complexity of reconstruction algorithms and reduce the measurements, two novel joint reconstruction algorithms for distributed compressed sensing based on joint sparse models were presented in this paper. Its application in signals and images processing was presented which are on the basis of demonstrating its feasibility. The result represent that the two novel joint reconstruction algorithms need fewer measurements for getting the same quality..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3825 (2015)
Obtaining and processing of Mueller matrix image
Yang Wei, Gu Guohua, Chen Qian, Zhou Xiaojun, and Xu Fuyuan
As the development of imaging technology, application of polarization information in this field has a wide鄄ranging appreciation gradually. Therefore, the way of extracting polarization information is particularly important. Mueller matrix, the coefficient matrix which shows the change of polarization state before and aAs the development of imaging technology, application of polarization information in this field has a wide鄄ranging appreciation gradually. Therefore, the way of extracting polarization information is particularly important. Mueller matrix, the coefficient matrix which shows the change of polarization state before and after light shining on object, not only has a closely relation to the material itself, but also contains quantities of polarization information. What忆s more, Mueller matrix has 16 elements each containing different information. Consequently, an adequate used on these information plays a catalytic role in target identification, information enhancement, as well as separation of target and background. Through presenting a method to acquire Mueller matrix image, a comparison was made with Dop(degree of polarization) information and at last the result indicated the value of Mueller matrix image in application of polarization imaging. The conclusion suggest that, compared with Dop image, the image processed by Mueller matrix has more integrity information, so as to provide a preferable foundation for pattern recognition later..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3831 (2015)
Spectrum matching technique in triple-spectrum color night vision system
Chen Yichao, Hu Wengang, Wu Dongsheng, He Yongqiang, and Li Xiaoming
True-color night vision system was designed to get true color of the targets at night. The theory of the system was analyzed. According to charcteristics of full moon light spectrum, combining the spectral reflected characteristics of typical target and spectrum response soope of S25+, using the principle of cintrast rTrue-color night vision system was designed to get true color of the targets at night. The theory of the system was analyzed. According to charcteristics of full moon light spectrum, combining the spectral reflected characteristics of typical target and spectrum response soope of S25+, using the principle of cintrast reversion and considering characteristics of visual of human's eyes，the spectrum intersected idea of triple-spectrum true-color night vision was presented in the end. According to the spectrum intersected idea, filters were designed and then their transmittance were measured. Experiment was carried out by the filters and a method to fuse triple-spectrum low-level light images was presented. The result shows that the proposed method could restore the true color of target..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3837 (2015)
High dynamic range image enhancement technology based on guided image filter
Xu Honglie, Chen Qian, Gu Guohua, and Zhang Yuzhen
The focal plane size of modern CCD/CMOS camera is getting bigger and bigger, that is to say, more and more pixels have been integrated on the focal plane array. Under this advance in technology, people can take a picture with higher resolution and higher dynamic range. The image contains much more information of the reThe focal plane size of modern CCD/CMOS camera is getting bigger and bigger, that is to say, more and more pixels have been integrated on the focal plane array. Under this advance in technology, people can take a picture with higher resolution and higher dynamic range. The image contains much more information of the real world. A serious problem of dealing with such kind of image is that, although the image has high dynamic range, people cannot display all the information of it. Certain technologies have been applied on modern cameras to solve this problem, but they still have some defects. A novel high dynamic range image enhancement algorithm was raised, which used the guided image filter to separate the image and deal with the detail layer as well as the base layer. The high frequency information needs to be enhanced to highlight the detail of the image on the detail layer. Meanwhile, the base layer controls the gray scale contrast which also needs to be processed with certain strategy. The color saturation can be controlled by both two layers. The raw high dynamic range image can be enhanced both through the detail layer and the base layer to improve its digital detail, gray scale rearranging and the color contrast. Detailed analysis of the procedure and figure demonstration were illustrated to show the ability of this algorithm..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 12, 3843 (2015)
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