Journals >Infrared and Laser Engineering
Contents
2019
Volume: 48 Issue 1
43 Article(s)
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[in Chinese]
Optically controlled graphene based terahertz modulator
Dai Zijie, Yang Jing, Gong Cheng, Zhang Nan, Sun Lu, and Liu Weiwei
A spectrally wide-band terahertz modulator based on monolayer graphene on germanium (GOG) was proposed. Utilizing a homemade THz-TDS (Terahertz-time domain spectroscopy) system, it was experimentally demonstrated that the THz modulator can be tuned by a 1 550 nm pump beam in a frequency range from 0.2 to 1.5 THz. The aA spectrally wide-band terahertz modulator based on monolayer graphene on germanium (GOG) was proposed. Utilizing a homemade THz-TDS (Terahertz-time domain spectroscopy) system, it was experimentally demonstrated that the THz modulator can be tuned by a 1 550 nm pump beam in a frequency range from 0.2 to 1.5 THz. The average transmittance of THz decreased from 40% to 22% when the pump power was increased to 250 mW, while the absorption coefficient averaged increased from 19 to 44 cm-1. The maximum modulation depth of the GOG modulator can reach as high as 62% at 0.38 THz and in a frequency range from 0.2 to 0.7 THz, the modulation depth was over 50%. Compared with bare Ge, it was proved that the modulation performance can be moderately enhanced by introducing monolayer graphene. This novel optically controlled graphene based THz modulator provides a feasible method for terahertz applications in communication and imaging..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 125001 (2019)
Dipole photoconductive antennas for broadband terahertz receiver
Pan Yi, Zheng Zhu, Ding Qing, and Yao Yong
Terahertz(THz) photoconductive antennas(PCAs) are widely used in the detection of broadband pulsed terahertz waves and are important components in THz spectroscopy and imaging systems. Due to its simple structure and ease of fabrication, the dipole photoconductive antenna is the mostly used antenna for THz receivers. TTerahertz(THz) photoconductive antennas(PCAs) are widely used in the detection of broadband pulsed terahertz waves and are important components in THz spectroscopy and imaging systems. Due to its simple structure and ease of fabrication, the dipole photoconductive antenna is the mostly used antenna for THz receivers. The primary specification of THz antennas is the bandwidth. To study the detection bandwidth of PCAs, dipole antennas with the arm length of 10, 50 and 150 μm and a bowtie antenna with the arm length of 178 μm were studied theoretically and experimentally. The results showed that the detection bandwidth decreased with the increase of the antenna arm length, which is consistent with the microwave antenna theory. Further, a commercial electromagnetic field numerical software was used for simulation. The results were in good agreement with the theoretical and experimental results and the model could be able to predict the performance of actual THz PCAs. The simulation can be used to design broadband and high sensitive THz antennas by optimizing structural parameters. The use of a hyper-hemispherical silicon substrate lens on the back of the receivers was also studied..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 125002 (2019)
Method of measuring steel bar in building by THz wave
Bi Lingzhi, Yuan Minghui, and Zhu Yiming
The parameters of steel bar (such as position, diameter, etc.) play an important role in the safety of the constructed buildings. A measurement method for position and diameter of the steel bar within the building by using terahertz wave was proposed. The terahertz wave was used as the detection signal to realize theseThe parameters of steel bar (such as position, diameter, etc.) play an important role in the safety of the constructed buildings. A measurement method for position and diameter of the steel bar within the building by using terahertz wave was proposed. The terahertz wave was used as the detection signal to realize these functions, which the terahertz wave had a strong penetrability to nonmetal building material (such as cement, brick, lime, etc.) and had the characteristics of almost total reflection to the metal (steel bar). At the same time, compared with the microwave, the terahertz wave was easy to achieve a very narrow antenna beam, which achieved high detection accuracy. And compared with the magnetic detector, it was not influenced by the external magnetic field environment. Theoretical analysis and engineering test show that this method can meet the requirements of actual engineering application..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 125003 (2019)
Target scene simulation of terahertz interferometric imaging with circular array
Wu Junzheng, Ni Weiping, Yan Weidong, and Zhang Han
Terahertz interferometric imaging technique based on the spectral domain, by sampling information of the spectral domain of the target scene to reconstruct the target image. It offers considerable potential in image acquisition rate and resolution for avoidance of scanning each pixel and ability to image with only a haTerahertz interferometric imaging technique based on the spectral domain, by sampling information of the spectral domain of the target scene to reconstruct the target image. It offers considerable potential in image acquisition rate and resolution for avoidance of scanning each pixel and ability to image with only a handful of detector elements. The terahertz interferometric imaging principle and implementation method were researched, then imaging resolution and effective field of view were focused on. Simulation experiments were carried out to analyze the influence of noise in target scene for imaging quality, and the results show that interferometric imaging is sensitive to noise. The reflection imaging model in security check was focused on which validated the applicability of the principle system. The conclusions from the simulation results may offer some theoretic evidence and technical support to designs of terahertz interferometric imaging system and practical applications..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 125004 (2019)
Terahertz holographic radar speckle suppression method based on multi-look correction of correlation angle
Jing Wen, Cui Zhenmao, Cheng Binbin, Jiang Ge, and Zhang Jian
In the MIMO based terahertz three-dimensional imaging radar for human security screening, the speckle effect affects the detection and recognition performance of hidden contraband seriously. For this reason, effective suppression of terahertz holographic speckle is demanded urgently. By using the angle based degree of In the MIMO based terahertz three-dimensional imaging radar for human security screening, the speckle effect affects the detection and recognition performance of hidden contraband seriously. For this reason, effective suppression of terahertz holographic speckle is demanded urgently. By using the angle based degree of freedom for speckle suppression obtained by the target rotation, a terahertz holographic radar speckle suppression method based on multi-look correction of correlation angle was proposed. Meanwhile, the angle sensitivity of the target scattering was carefully considered. In theory, the normalized covariance expression of the holographic radar speckle intensity under the relevant angle illumination was derived, and the speckle contrast after multi-view processing was given. Experimentally, based on the fast speed of the 340 GHz MIMO based imaging system, single-look images of low-speed rotating target were obtained. The imaging space rotation correction, target registration and multi-look processing were performed on each single-look image under the relevant viewing angle. The speckle contrast of the averaged reconstructed image was reduced to 44% of a single reconstructed image. The processed speckle was effectively suppressed with distinct target contour and details. The proposed method can effectively suppress speckle noise and achieve image enhancement without increasing system complexity..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 125005 (2019)
Detection of hydration number of tert-butyl alcohol solution based on terahertz technology
Wu Xueyang, Yang Jingyi, Wang Yingying, Zhang Zhenrong, and Song Ruixin
In this paper, based on the terahertz time-domain spectroscopy (THz-TDS), the tert-butyl alcohol solutions with different concentrations were measured, and the curves of the absorption coefficient from 0.3 to 1.0 THz were obtained. The difference between the experimental results and theoretical calculation were analyzeIn this paper, based on the terahertz time-domain spectroscopy (THz-TDS), the tert-butyl alcohol solutions with different concentrations were measured, and the curves of the absorption coefficient from 0.3 to 1.0 THz were obtained. The difference between the experimental results and theoretical calculation were analyzed by model of packing density. It is concluded that under the proper conditions, using THz-TDS technology for testing and data analysis, the hydration number of tertiary butyl alcohol solution can be calculated effectively. These results are valuable for the later analysis of the solution system of alcohol molecules..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 125006 (2019)
[in Chinese]
Inversion of particle size distribution of small angle forward scattering based on polarization ratio method
Shan Liang, Xu Liang, Hong Bo, Cao Lixia, Wang Daodang, Guo Tiantai, and Kong Ming
In light scattering particle size measurement method, the results based on the traditional measurement model are easily affected by particle impurities in optical path. On the basis of Mie theory, the new relationship between scattering light energy and particle size distribution was derived by combining the small anglIn light scattering particle size measurement method, the results based on the traditional measurement model are easily affected by particle impurities in optical path. On the basis of Mie theory, the new relationship between scattering light energy and particle size distribution was derived by combining the small angle forward scattering method with the polarization ratio method. Two objective functions of the traditional small angle forward scattering method and the polarization ratio method of small angle forward scattering were constructed, and an independent mode algorithm, the artificial fish swarm algorithm(AFSA), was introduced to invert the objective functions. In simulations, uniform spherical particles that obey the unimodal distribution of Johnson-SB were used, and the scattering intensity values of the two target functions were added to the random noise of 5%, 10% and 15% respectively, the results demonstrate that the inversion accuracy, anti-noise performance and robustness of the polarization ratio method are significantly better than those of the traditional small angle forward scattering method..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 117001 (2019)
Potassium spectrum detection and extraction based on spatial heterodyne
Wang Xinqiang, Wang Huan, Ye Song, Wang Jiejun, Zhang Wentao, and Wang Fangyuan
The secondary combustion radiation of rocket plume can be significantly reduced by using potassium flame agent, which leads to unprecedented improvement of missile invisibility. With the advantage of spatial heterodyne spectroscopy on weak spectrum signal detailed detection, potassium signal detection experiment in misThe secondary combustion radiation of rocket plume can be significantly reduced by using potassium flame agent, which leads to unprecedented improvement of missile invisibility. With the advantage of spatial heterodyne spectroscopy on weak spectrum signal detailed detection, potassium signal detection experiment in missile plume spectrum was performed by a near infrared spectrum instrument. Alcohol burner flame was used to simulate the missile plume, while the outside sky was regarded as background. Two of the modern spectral estimation methods, Autoregressive AR algorithm and MUSIC algorithm, were used to extract the potassium signal. Both algorithms can suppress noise, extract potassium signal and narrow the width of its characteristic peaks. For AR algorithm, the characteristic peak of 766.49 nm reduce 21% respectively, and noise reduce 42%. While for MUSIC algorithm, those characteristic peak reduce 50% and noise reduce 47%. The results illustrate that MUSIC algorithm has a better performance, and the application that using spatial heterodyne technology to identify the jet aircraft such as missiles is feasible..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 117002 (2019)
Stray light analysis on LAMOST high-resolution spectrograph
Zhang Tianyi, Hou Yonghui, Xu Teng, Jiang Haijiao, Xin Qiqige, and Zhu Yongtian
In order to improve the spectral resolution and spectrograph efficiency of LAMOST-HRS(Large Sky Area Multi-Object Fiber Spectroscopy Telescope-High Resolution Spectrograph), and set up the methods to analyze stray light in the conceptual design stage, the modeling and analysis of stray light without measuring BSDF wereIn order to improve the spectral resolution and spectrograph efficiency of LAMOST-HRS(Large Sky Area Multi-Object Fiber Spectroscopy Telescope-High Resolution Spectrograph), and set up the methods to analyze stray light in the conceptual design stage, the modeling and analysis of stray light without measuring BSDF were studied. First, the Harvey scattering model was constructed by calculating the key parameters according to the roughness measurement data. Then the optical surface was observed by microscope, and the maximum partical diameter was obtained by MATLAB image processing, and the particle pollution scattering model was built. The the coatings, optical element and mechanical structure of the spectrograph were imported. The mechanical structure was simplified to improve the efficiency of the analysis. Finally, the background of the stray light was estimated, and the path and composition of the stray light were analyzed. The results show that the LAMOST-HRS stray light is mainly caused by the scattering of optical surface. The stray light accounts for 2.55% of the total illumination of the CCD surface, and the signal-to-noise ratio is 16.01 dB, which meets the design requirements..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 117003 (2019)
Space object deconvolution from wavefront sensing by wavefront phase modelling based on simplex splines function
Guo Shiping, Yang Ning, Zhang Ziteng, Hu Suhai, and Zhang Rongzhi
An image restoration method for ground-based adaptive optics telescope imaging was proposed in the case of simultaneous recording of short exposure images and wavefront sensor measurements. The proposed method was based on a zonal representation of the turbulence-degraded wavefront phase using bivariate simplex splinesAn image restoration method for ground-based adaptive optics telescope imaging was proposed in the case of simultaneous recording of short exposure images and wavefront sensor measurements. The proposed method was based on a zonal representation of the turbulence-degraded wavefront phase using bivariate simplex splines function, instead of the traditional Zernike modal decomposition; an average slopes measurement model for Shack-Hartmann wavefront sensor was then built based on the zonal representation method, which transformed the ill-posed wavefront reconstruction problem into a well-conditioned equality constrained least squares problem. The object image was finally obtained by non-blind Richardson -Lucy iterative deconvolution. Simulated experiments show that the proposed method performs superior image restoration results and noise suppression capability in different turbulence strength..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 117004 (2019)
[in Chinese]
Novel multitap complex coefficient microwave photonic filter
Yan Yi, Liao Tongqing, Lv Xiaoguang, Jiang Tiezhen, and Cai Peijun
A kind of multitap complex coefficient microwave photonic filter was proposed based on novel tunable multi-wavelength fiber laser and stimulated Brillouin scattering(SBS). The complex coefficient was realized based on a phase shift introduced by SBS. The phase shift was controlled by adjusting the pump power of SBS, anA kind of multitap complex coefficient microwave photonic filter was proposed based on novel tunable multi-wavelength fiber laser and stimulated Brillouin scattering(SBS). The complex coefficient was realized based on a phase shift introduced by SBS. The phase shift was controlled by adjusting the pump power of SBS, and so the center frequency of the filter was adjusted continuously. 16 laser signals with wavelength intervals of 0.338 nm were obtained based on a tunable multi-wavelength high erbium doped fiber laser in experiment. And then, the influence on this filter by the length of SBS gain medium, the number of the taps and the wavelength interval were researched by simulation..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 120001 (2019)
Influence of surface cleanliness of optical element on its surface scattering characteristics
Huang Cong, You Xinghai, and Zhang Bin
Aimed at the light scattering problem from the particles on optical surfaces of the systems in practical applications, and taken Al2O3 particles in air as an example, the variations of the bidirectional reflection distribution function(BRDF) with the scattering angle on the surfaces of optical components were simulatedAimed at the light scattering problem from the particles on optical surfaces of the systems in practical applications, and taken Al2O3 particles in air as an example, the variations of the bidirectional reflection distribution function(BRDF) with the scattering angle on the surfaces of optical components were simulated and analyzed based on Mie scattering theory, and then the total integral scattering (TIS) value of the surface was calculated quantitatively. On this basis, the effect of the BRDF and the TIS value were further analyzed under the conditions of different air cleanliness levels, the direction of the optical component surface, the exposure time. The results indicate that, the air cleanliness levels, the direction of the optical component surface and the exposure time have effect on scattering of the optical surface, in which the direction of optical components has significant impact on the scattering of the surfaces. When the particles buildup on horizontal upward facing surfaces(TIS=3.93×10-3), the amount of scattering increases by an order of magnitude compared with that of the vertical ones(TIS=4.07×10-4), and increases by two orders of magnitude compared with that of the downward ones(TIS=5.22×10-5). Finally, based on the Cassegrain telescope, aimed at the tolerance of the particles on the primary mirror, the exposure time reaching the tolerance was carried out with different air cleanliness levels. The results can provide reference for particle control and reliability for effective detection of the weak signal in practice..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 120002 (2019)
Technology of target trajectory extrapolation with M word PIR array square model
Liu Xibin, Yang Wei, Chen Xiaole, Liu Ning, and Zeng Liang
Aiming at the limitations of single pyroelectric infrared sensor(PIR) array in the target trajectory measurement, the method of using four PIR array sensing platforms to form the square perceptive model was put forward to measure the target trajectory. In this study, eight PIR probes were used to form M word array, witAiming at the limitations of single pyroelectric infrared sensor(PIR) array in the target trajectory measurement, the method of using four PIR array sensing platforms to form the square perceptive model was put forward to measure the target trajectory. In this study, eight PIR probes were used to form M word array, with each probe evenly distributed at 45 degrees intervals. Four PIR array sensing platforms were arranged at the four vertices of the square model, and 32 senor angle data fusion through the adaptive weighted fusion algorithm of multi-sonsor data. At last, four sensing platforms used the coordinate and time information of the detected target to calculate the target′s motion trajectory and obtained the target′s speed. The experimental results show that this method can effectively make up for the deficiency of the function which can only realize positioning and low accuracy of single PIR array, and realize the accurate measurement of motion trajectory and the prediction of the target position in time sequence. So, this method has great theoretical significance and practical application value..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 120003 (2019)
Synergistic effect of hybrid nanodiamond/ZnO nanowires for improved ultraviolet photoresponse
Jiang Haitao, Liu Shibin, and Yuan Qianqian
ZnO-based photodetectors (PDs) have a small on/off ratio and long response time, which hamper their practical UV detection. Herein, a facile method to prepare a nanodiamond (ND)-decorated ZnO nanowire (ZNW) ultraviolet photodetector was demonstrated. This hybrid ZnO -ND UV photodetector considerably improved photodetecZnO-based photodetectors (PDs) have a small on/off ratio and long response time, which hamper their practical UV detection. Herein, a facile method to prepare a nanodiamond (ND)-decorated ZnO nanowire (ZNW) ultraviolet photodetector was demonstrated. This hybrid ZnO -ND UV photodetector considerably improved photodetection performance compared with bare ZnO. This hybrid device simultaneously exhibited remarkable detectivity, rapid response, and decent current on/off ratio. This excellent performance was attributed to the synergistic effect between NDs and the ZNWs. These results introduce a new scenario for designing and fabricating an innovative optoelectronic system..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 120004 (2019)
[in Chinese]
Imaging analysis and control design of large field of view stitching system with a single lens
Zhang Xiang, and Gao Yunguo
A large field of view stitching method with a single lens was proposed to meet the requirement of remote target capture. An experimental prototype was designed to verify the method, and the imaging characteristics of the prototype were analyzed. The structural design of the prototype and the camera exposure control proA large field of view stitching method with a single lens was proposed to meet the requirement of remote target capture. An experimental prototype was designed to verify the method, and the imaging characteristics of the prototype were analyzed. The structural design of the prototype and the camera exposure control process were introduced. Then according to the imaging method, by controlling the continuous conic rotation of the camera to realize large-field imaging, the image motion feather of the prototype and the influence of the motion tolerance on the correct splicing of the sub-images were analyzed. At last the control parameters were designed to make the camera expose to the proper field when the prototype was in running. In the experiment, the parameters of the prototype were substituted into the analysis results, the image motion value was obtained by calculation, and the stitching deviation of the sub-images caused by the camera motion error was checked. Finally the large field image that was stitched correctly was obtained according to the camera exposure control parameters obtained by calculation. The imaging characteristics of the experimental prototype were analyzed, which laid the foundation for engineering application of the large-field stitching method..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 118001 (2019)
Design of coaxial four-mirror anastigmat optical system with long focal length
Chen Li, Liu Li, Zhao Zhicheng, Li Yingbo, Fu Danying, and Shen Weimin
The earth-observing remote sensing micro/nano satellite with low-cost and high-performance is the focus of the current research and development. In order to adapt to the micro/nano satellite′s platform, the camera is often required to be compact and light weight. Limited of its volume and weight, designing a long focalThe earth-observing remote sensing micro/nano satellite with low-cost and high-performance is the focus of the current research and development. In order to adapt to the micro/nano satellite′s platform, the camera is often required to be compact and light weight. Limited of its volume and weight, designing a long focal length, wide-field telescope as compact as possible is the key of successfully manufacturing the high-resolution remote sensing optical camera. The possibility of solving this problem by using on-axis four-mirror system is studied. First of all, the basic composition and the working principle of on-axis four-mirror system without secondary obscuration was introduced. Then, the conditions of geometric constraint and the formulas of primary aberrations were presented based on Gauss and optical aberration theory. The design idea and method of the compact on-axis four-mirror system with long focal length were presented. Finally, an optimized optical system was given, with full field angle is 1°×1°, effective focal length (EFL) is 2 100 mm, F number is 7, respectively. The total length of this system is 228 mm, only about 1/9 of EFL. This optical system is simple and compact and its imaging quality is near diffraction limit..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 118002 (2019)
Design and experiment of multi rotor UAV control system with spectral remote sensing load
Pei Xinbiao, Wu Helong, Ma Ping, Yan Yongfeng, Hao Peng, and Bai Yue
As a new low-cost remote sensing platform, rotor UAV has been paid much attention by researchers and applications. Rotor UAV equipped with commercial remote sensing has many advantages, such as high ground resolution, quick response and easy maintenance, which make up for the shortcomings of traditional remote sensing,As a new low-cost remote sensing platform, rotor UAV has been paid much attention by researchers and applications. Rotor UAV equipped with commercial remote sensing has many advantages, such as high ground resolution, quick response and easy maintenance, which make up for the shortcomings of traditional remote sensing, in practical use the anti-interference ability has become an important part of the remote sensing system of the rotor. In order to make up for the lack of conventional multi rotor torque heading control, firstly, six axis twelve-rotor UAV structure was designed and its dynamic model was established, then according to the anti disturbance capability of agricultural remote sensing platform requirements, the special algorithm of active disturbance rejection controller(ADRC) was designed with differential tracker, extended state observer and nonlinear state error feedback control law. Secondly, the stability and effectiveness of the controller was verified by simulation. The real wind disturbance test shows that the control algorithm maintains good trajectory tracking characteristics under the influence of instantaneous wind disturbance of 11.2 m/s. Finally, the UAV equipped with self-developed commercial high micro spectrometer MNS2001 and two axis stabilized in six axis twelve tilt rotor, fixed spectral remote sensing measurements in a particular area of rice over 300-900 nm in the spectral range, spectral reflectance hovering over the region of multiple measurement relative error was less than 5%. The test results show that the rotor has a good platform for remote sensing stability and reliability can be further applied in the field of agricultural remote sensing and auxiliary production management..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 118003 (2019)
Development of imaging system with bionic moth-eye anti-reflection structure
Dong Tingting, Zhang Guowei, Guo Jie, Wu Jinshuang, Zhang Weiguo, and Fu Yuegang
Bionic moth-eye is a kind of micro-nano structure with anti-reflection ability. Random distributed double-sided bionic moth-eye antireflective nanoscale lens was manufactured by chemical precipitation silver method, with an average transmittance of over 97%. It could be concluded that the transmittance of random moth-eBionic moth-eye is a kind of micro-nano structure with anti-reflection ability. Random distributed double-sided bionic moth-eye antireflective nanoscale lens was manufactured by chemical precipitation silver method, with an average transmittance of over 97%. It could be concluded that the transmittance of random moth-eye structure was better than that of period structure at the design wavelengths by analyzing the transmittance of both period and random moth-eye structures under the conditions of the same parameter combinations. The moth-eye lens was used to calculate the related parameters, and a whole moth-eye imaging lens was designed by using CODE V platform. This moth-eye optical system has an effective focal length of 25.5 mm, an F-number of 5, a field of view of 13°, a spectral range of 400-700 nm. Compared with conventional coating lens, the moth-eye lens has a good inhibition effect on the ghosts, edge glare and other stray light by performing the imaging contrast test..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 118004 (2019)
Optimization of the lens structure based on the line of sight jitter error in Isight environment
Yang Fengfu, Tian Haiying, Yan Changxiang, Wu Congjun, and Mu Deqiang
To achieve the best structure performance of the airborne polarization imaging spectrometer lens which meets the optical performance, the optimization model based on the line of sight jitter error was established and calculated in Isight environment. Firstly, the principle that the line of sight jitter error affected tTo achieve the best structure performance of the airborne polarization imaging spectrometer lens which meets the optical performance, the optimization model based on the line of sight jitter error was established and calculated in Isight environment. Firstly, the principle that the line of sight jitter error affected the performance of the optical system was elaborated and the initial structure layout was designed according to the optical model and performance. Secondly, the calculation method of the line of sight jitter error was deduced, based on which the optimization model was established. Finally, the optimization model was calculated by applying the Multi-island Genetic Algorithm in Isight environment. The computational result of the integrated optimization model shows that the mass of the lens barrel is reduced by 17.4%, which satisfying the constraint of the optimization model and the value of the optical transfer function is 0.4(77 lp/mm), which meeting the requirement. The line of sight jitter error is applied during the procedure of the structure optimization presented, which expanded the connotation of optomechanic structure optimization and provided a new optimization idea for the same kind of structure..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 118005 (2019)
Imaging property analysis of segmented mirror
Li Yichao, Kang Fuzeng, and Wang Hao
Segmented errors have important influence on the image quantity of segmented mirror. The complex amplitude distribution of reflected lightwave corresponding to single segment was given based on the scalar diffraction theory. The analysis model which characterized the impact of segmented errors was established by procesSegmented errors have important influence on the image quantity of segmented mirror. The complex amplitude distribution of reflected lightwave corresponding to single segment was given based on the scalar diffraction theory. The analysis model which characterized the impact of segmented errors was established by processing the segmented errors through coordinate transformation method. The Point Spread Function (PSF) and Strehl Ratio (SR) curves corresponding to various segmented errors were got by numerical simulation. The results show that SR curves corresponding to piston errors are periodic. The SR curves corresponding to tip-tilt errors and segment gaps have same structures. The conclusion provides a support for the image quantity analysis of segmented mirror..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 118006 (2019)
[in Chinese]
Estimation and verification of high-accuracy laser ranging on several photons
Liu Hongbin, Li Ming, Shu Rong, Hu Yihua, and Huang Genghua
A new high-accuracy laser ranging technology based on several photons was mentioned and verified, according to traditional linear detection needing high laser energy and photon counting detection hard to distinguish the avalanche events generated by signal or noise. Silicon Photomultiplier was used as echo detector, maA new high-accuracy laser ranging technology based on several photons was mentioned and verified, according to traditional linear detection needing high laser energy and photon counting detection hard to distinguish the avalanche events generated by signal or noise. Silicon Photomultiplier was used as echo detector, making analysis of the echo response model, noise characteristics and ranging accuracy. Laser ranging system was set up to measure target of the 107.86 m at laser wavelength of 532 nm and energy of 10 nJ. Experimental verification result indicates that the noise is a random distribution, which maximum magnitude equals to three pixels fired at the same time. When threshold is set above that, noise and signal can be clearly distinguished. For echo signal containing 32 photons, about four pixels are fired. Meanwhile, ranging accuracy of the system is up to 3 cm at 3 sigma..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 106001 (2019)
Photon counting laser bathymetry system
Zhang Hehui, Ding Yuxing, and Huang Genghua
A single wavelength(532 nm), short-pulse(400 ps), low pulse energy(0.5 μJ), high pulse repetition rate(10 kHz), short dead time of detector(22 ns) and high resolution of time interval(50 ps) photon counting laser bathymetry system was designed. The principle of photon counting laser bathymetry and its superiority to thA single wavelength(532 nm), short-pulse(400 ps), low pulse energy(0.5 μJ), high pulse repetition rate(10 kHz), short dead time of detector(22 ns) and high resolution of time interval(50 ps) photon counting laser bathymetry system was designed. The principle of photon counting laser bathymetry and its superiority to the typical airborne laser bathymetry was introduced. The relationship between the average number of photoelectrons generated at the receiver and the transmitted laser pulse energy was analyzed, indicating that the bathymetry capability of the system was about 3.7 m. Experiments were conducted in a pond with a Secchi depth of 1.2 meters, and the underwater information down to 2 m depths were successfully obtained by filtering and solving the point cloud data..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 106002 (2019)
All-solid-state picosecond radially polarized laser and its processing characteristics
Peng Hongpan, Yang Ce, Lu Shang, and Chen Meng
An average power of 1.95 W picosecond radially polarized laser was obtained with 1 064 nm at 1 kHz, which based on an all-solid-state picosecond laser developed independently. The peak power of the radially polarized beam was up to 1.77×108 W and the beam quality was measured to be M2=2.95 with the pulse width 11 An average power of 1.95 W picosecond radially polarized laser was obtained with 1 064 nm at 1 kHz, which based on an all-solid-state picosecond laser developed independently. The peak power of the radially polarized beam was up to 1.77×108 W and the beam quality was measured to be M2=2.95 with the pulse width 11 ps, corresponding to the beam purity of 92%. The radially polarized seed beam was obtained by adding the polarization conversion element outside the laser cavity. In addition, the modulation attenuator caused two different polarization lasers to output the same optical power and then enter the subsequent optical system; and a 0.5 mm thick stainless steel was drilled and grouted by using the obtained picosecond radially polarized laser and picosecond linearly polarized laser under the same processing parameters, respectively. The difference on the circularity of the holes and the depth of the grooves were compared with each other when it was processed by the two polarized picosecond lasers. The results show that the picosecond radially polarization laser has better drilling roundness, deeper notch depth and flatter sidewall of the groove compared to the picosecond linear polarization laser processing results. This results provides a reference for the application of picosecond radial polarization laser in the field of material processing..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 106003 (2019)
Study on spot size and photon return of a sodium laser guide star
Huang Jian, Wei Kai, Jin Kai, Wang Gongchang, Li Min, and Zhang Yudong
The sodium laser guide star facility has become one of the most important subsystems of adaptive optics system for large ground-based telescope. Spot size and photon return of the sodium laser guide star are the main factors that affect the performance of an adaptive optics system, both of which depend strongly on the The sodium laser guide star facility has become one of the most important subsystems of adaptive optics system for large ground-based telescope. Spot size and photon return of the sodium laser guide star are the main factors that affect the performance of an adaptive optics system, both of which depend strongly on the laser power density distribution at the sodium layer and the coupling efficiency of the laser. In order to accurately estimate the photon return and spot size, a model was established for laser propagation in atmosphere and the effect of laser launch telescope′s diameter and turbulence in the uplink path on the power density distribution was analyzed. A general technique to optimize the laser launch telescope′s design was devised. Then the spot size and photon return according to the relationship between the power density and the coupling efficiency were calculated. By minimizing measurement error and temporal error, an optimal sampling frequency was obtained. The researching results show that, for atmosphere condition at Gaomeigu Lijiang (median value of Fried parameter (r0) is 7 to 9 cm at a wavelength of 550 nm), the minimum spot size occurs when the diameter of the laser launch telescope is 300 mm. For an r0 value of 9 cm and at a laser power of 20 W with D2a+D2b re-pumping, the photon return of the sodium laser guide star is expected to be 1.3×107 photons·s-1·m-2 and the spot size is 0.6 ″. The optimal sampling frequency is around 900 Hz..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 106004 (2019)
Research on the long-range and compact photon counting ladar system under sunlight condition
Wang Haiwei, Ding Yuxing, Huang Genghua, Hou Jia, and Shu Rong
A compact design of photon counting 3D imaging ladar was proposed, which can be used in full-time remote detection applications but with strict restrictions on the size and weight, such as high-speed vehicle guidance, high-speed UAV, helicopter, ship navigation and obstacle avoidance, and railway track obstacles explorA compact design of photon counting 3D imaging ladar was proposed, which can be used in full-time remote detection applications but with strict restrictions on the size and weight, such as high-speed vehicle guidance, high-speed UAV, helicopter, ship navigation and obstacle avoidance, and railway track obstacles exploration. This design adopted high sensitivity photon counting technology, common aperture for laser transmission and receives, as well as conjugate optics in the telescope. And the two-dimensional scanning mechanism was placed in the rear of the telescope, to expand the telescope aperture, improve the detecting range and reduce the size of scanning mirror. With a smaller scanning mirror, the scanning speed was further improved. The laser transceiver was designed with a narrow divergence angle and narrow instantaneous common FOV. Combined with the application of ultra narrowband filter, the ladar system can achieve good performance under the strong daylight noise condition. At last, key technologies of high repetition laser emission, emission stray light suppression, polarization degradation, photon counting sunlight background denoising use in this design were discussed..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 106005 (2019)
Estimation of global detection depth of spaceborne oceanographic lidar in blue-green spectral region
Liu Bingyi, Li Ruiqi, Yang Qian, and Kong Xiaojuan
In order to evaluate and analyze the detection performance of lidar for optical properties in global ocean, the detection depth of spaceborne oceanographic lidar operating in blue-green spectral region was estimated and analyzed. This research was based on lidar equation and given lidar parameters. MODIS Level 3 annualIn order to evaluate and analyze the detection performance of lidar for optical properties in global ocean, the detection depth of spaceborne oceanographic lidar operating in blue-green spectral region was estimated and analyzed. This research was based on lidar equation and given lidar parameters. MODIS Level 3 annual averaged global water absorption coefficient a(λ) and backscatter coefficient bb(λ) were used as reference values for optical properties of sea water. The results show the distribution of detection depth depends on both detection wavelength and water optical properties. In clear open ocean, the best detection wavelength is near 460 nm and the maximum detection depths are approximated 110 m and 120 m in daytime and nighttime, respectively. In turbid coastal water, the best detection wavelength is mostly longer than 500 nm and the maximum detection depths can only reach 20 m or even shallower. The spaceborne oceanographic lidar achieves best global detection performance when the detection wavelength is between 470 nm and 480 nm..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 106006 (2019)
Ranging calibration model of terrestrial laser scanner based on gray level priority
Yang Shujuan, Zhang Keshu, and Shao Yongshe
For the priority order of the multiplication constant correction and the gray correction, a gray-scale priority calibration model was proposed. Firstly, the main error sources of pulsed ranging were analyzed. Then the existence of the multiplication constant and distance correction table and the influence of gray scaleFor the priority order of the multiplication constant correction and the gray correction, a gray-scale priority calibration model was proposed. Firstly, the main error sources of pulsed ranging were analyzed. Then the existence of the multiplication constant and distance correction table and the influence of gray scale on the multiplication constant were verified. Then the consistency of the distance correction table at different distances was verified. Finally, a gray-scale prionty distance calibration model was provided. In order to obtain different gray-scale data, two-dimensional scanning of different gray-scale target plates was carried out by using ground laser scanner. The accuracy of different distance calibration models was compared by using different distance data. The experimental results show that accuracy of the gray-scale priority calibration model is higher than the precision of the constant priority calibration model, and the distance accuracy is improved to 5 mm. At the same time, the result of the gray-scale priority calibration model is not affected by the gray scale and has universality..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 106007 (2019)
Ultrashort pulse laser drilling of micro-holes (part 1)--theoretical study
Zhao Wanqin, Mei Xuesong, and Wang Wenjun
Since the invention of lasers in the 1960s, the pulse duration has being continuously shorten down to the sub-picosecond and even femtosecond regime. It makes the laser processing technology to the ultrashort pulse laser era. In order to further optimize the ultrashort pulse laser micro-machining, theoretical study is Since the invention of lasers in the 1960s, the pulse duration has being continuously shorten down to the sub-picosecond and even femtosecond regime. It makes the laser processing technology to the ultrashort pulse laser era. In order to further optimize the ultrashort pulse laser micro-machining, theoretical study is indispensable. The interaction mechanism between ultrashort pulse laser and different types of materials were presented. The typical physical properties, such as plasma effect, self-focusing and filamentation, and conical radiation, were discussed. The theoretical studies for ultrashort pulse laser drilling of micro-hole were analyzed. Furthermore, the challenging issues were obtained..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 106008 (2019)
[in Chinese]
Highly efficient RTP electro-optic Q-switched Nd:YVO4 laser by end-pumping at 914 nm
Hu Xing, Cheng Dejiang, Guo Zhiyan, Jiang Menghua, Hui Yongling, Lei Hong, and Li Qiang
An electro-optic (EO) Q-switched Nd:YVO4 laser with high repetition rate, end-pumped by continuous-wave (CW) laser diode (LD) was reported. Using RbTiOPO4(RTP) single crystal as an EO Q-switch, by matching mode of oscillation light and pump light, 1 064 nm laser output with high efficiency, high repetition and short puAn electro-optic (EO) Q-switched Nd:YVO4 laser with high repetition rate, end-pumped by continuous-wave (CW) laser diode (LD) was reported. Using RbTiOPO4(RTP) single crystal as an EO Q-switch, by matching mode of oscillation light and pump light, 1 064 nm laser output with high efficiency, high repetition and short pulse width was realized. On the one hand, low absorption coefficient of 914 nm wavelength was adopted to pump Nd:YVO4 crystal, so that the heat distribution inside the crystal was uniform, thereby achieving high quantum efficiency while reducing the thermal effect. On the other hand, the pump light spot radius was optimized to match mode of pump light and oscillation light. At the repetition rate of 200 kHz, the maximum average output power of 16 W, full width at half maximum of pulses of 9 ns, single pulse energy of 80 μJ and beam quality M2＜1.2 are achieved at an absorption pump power of 31 W, corresponding to an optical conversion efficiency of 51.6%. To the best of our knowledge, this is the highest efficiency reported on the EO Q-switched laser by using RTP crystals..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 105001 (2019)
915 nm semiconductor laser new type facet passivation technology
Wang Xin, Zhu Lingni, Zhao Yihao, Kong Jinxia, Wang Cuiluan, Xiong Cong, Ma Xiaoyu, and Liu Suping
Aiming at the mechanism of catastrophic optical damage of semiconductor laser cavity surface, a single-chip semiconductor laser cavity surface vacuum cleavage passivation process was designed. The cleavage process in vacuum and direct evaporation of passivation film on the surface of semiconductor laser cavity was propAiming at the mechanism of catastrophic optical damage of semiconductor laser cavity surface, a single-chip semiconductor laser cavity surface vacuum cleavage passivation process was designed. The cleavage process in vacuum and direct evaporation of passivation film on the surface of semiconductor laser cavity was proposed. Using ZnSe material as the passivation film material for the vacuum cleavage process of single-die semiconductor laser, it was found that the vacuum cleavage passivation process and ZnSe material could be used as the passivation film to increase the output power of the device by 23%. The mechanism of semiconductor laser cavity surface damage was analyzed by electroluminescence (EL). It is further explained that the introduction of vacuum cleavage passivation technology in the preparation process of 915 nm semiconductor laser and the selection of ZnSe as the passivation film can effectively protect the cavity surface of the semiconductor laser and improve device reliability..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 105002 (2019)
Research on LD pumped 1.06 μm burst-mode laser and the amplification systems
Duan Jialin, Li Xudong, Wu Wentao, Lin Sen, Fan Rongwei, Dong Zhiwei, Zhou Zhigang, and Chen Deying
In recent years, with the increasing demand for optoelectronic technology applications, more and more fields such as Plane Laser Induced Fluorescence, laser detection and laser processing have shown the demand for high-repetition-rate and high-energy pulsed lasers. However, due to the limitation of average power, it isIn recent years, with the increasing demand for optoelectronic technology applications, more and more fields such as Plane Laser Induced Fluorescence, laser detection and laser processing have shown the demand for high-repetition-rate and high-energy pulsed lasers. However, due to the limitation of average power, it is difficult for the conventional continuous pulsed lasers to achieve pulsed laser output with high repetition rate and high energy. In this paper, an LD-pumped 1.06 μm Nd:YAG burst-mode laser and its amplification system were studied and demonstrated. By employing long pump duration, burst-mode technique, and MOPA amplification scheme, the laser output with high repetition rate and high energy was obtained in the burst duration. After dual-stage amplification, the burst energy reached 170.4, 211.8, and 220.3 mJ at Q-switching repetition rate of 10, 50, and 100 kHz, containing 2, 12 and 25 pulses in one pump duration, respectively. The single pulse energy reached 85.2, 17.7, and 8.8 mJ, respectively..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 105003 (2019)
Influence of V-cavity parameters on laser output performance
Wei Yong, Fan Yiming, Li Hongmin, Tao Jiayou, Qian Kun, and Zhou Yueping
In order to make the laser with V-resonator have good output performance, it is necessary to find the influence rules of cavity parameters on the laser output performance in laser cavity design. Combining the graphic analysis method of V-type folded cavity and the equivalent cavity analysis method of multicomponent optIn order to make the laser with V-resonator have good output performance, it is necessary to find the influence rules of cavity parameters on the laser output performance in laser cavity design. Combining the graphic analysis method of V-type folded cavity and the equivalent cavity analysis method of multicomponent optical resonator, the stability of the equivalent coaxial spherical cavity and the output laser beam quality were theoretically solved and analyzed after equivalent approximation of the folded cavity. The internal relationship between the V-type folded cavity parameters and the laser output performance were found. By calculating the given conditions, some results were known. The ideal value range of total cavity length L is 70-80 mm with the optimal value 75 mm when the folding angle θ is equal to 0.15π. The allowable variation range of curvature radius of end mirrors R1 and R2 is 60-80 mm. And the curvature radius of of folding mirror R3 has a minimum value of 45 mm. The laser spot radius and the far-field divergence angle of fundamental mode on the right (left) end mirror will become larger with the increase of g-parameters of left(right) subcavity. The above-mentioned equivalent cavity analysis method and the achieved results can provide an important reference theoretically for the cavity optimization design..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 105004 (2019)
[in Chinese]
High power high repetition rate femtosecond Ytterbium-doped fiber laser frequency comb (invited)
Sun Jinghua, Sun Kexiong, Lin Zhifang, Sun Jifen, Jin Lu, and Xu Yongzhao
Femtosecond optical frequency combs have introduced revolutionary promotions to precision optical spectroscopy and metrology, and have been hot topics of laser technologies and applications for two decades. In this article, the affects of intracavity dispersion and mode-locking mechanism on carrier-envelope phase slip Femtosecond optical frequency combs have introduced revolutionary promotions to precision optical spectroscopy and metrology, and have been hot topics of laser technologies and applications for two decades. In this article, the affects of intracavity dispersion and mode-locking mechanism on carrier-envelope phase slip frequency(fCEO) of femtosecond laser pulse trains were researched based on a femtosecond Ytterbium-doped fiber laser with 250 MHz repetition rate. By optimizing the intracavity dispersion, pumping power, and detection methods, 49 dB signal-noise-ratio fCEO beat signal was obtained which then was stabilized it to a stability of 3.2×10-10 in 1 second, and a stability of 3.4×10-13(1 s) of frep was also achieved. In addition, the effects of pulse chirping on the output pulse duration of a fiber amplifier was researched based on a piece of large-mode-area photonic crystal Yb doped fiber. Under 60 W of pumping power from a laser diode at 976 nm wavelength, 23 W average output power from the amplifier with 66 fs pulse duration and 250 MHz repetition rate was achieved when the seed pulses were carring -3.8×104 fs2 pre-chirping dispersion..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 103001 (2019)
Recent advances in multi-wavelength ultrafast lasers based on nonlinear effects of 2D materials(invited)
Guo Bo
Multi-wavelength ultrafast lasers play an important role in a variety of applications ranging from optical communications to medical diagnostics and optical sensing. Two-dimensional (2D) materials, including graphene, topological insulators, transition metal dichalcogenides, and phosphorene, have witnessed a very fast Multi-wavelength ultrafast lasers play an important role in a variety of applications ranging from optical communications to medical diagnostics and optical sensing. Two-dimensional (2D) materials, including graphene, topological insulators, transition metal dichalcogenides, and phosphorene, have witnessed a very fast development of both fundamental and practical aspects in ultrafast photonics since 2009. Their unique nonlinear optical properties enable them to be used as excellent saturable absorbers with fast responses and broadband operation and can be easily integrated into lasers. Here, we review the recent advances in the exploitation of these 2D materials in multi-wavelength ultrafast lasers. Interestingly, study found that, 2D materials-based nonlinear optical device is an ideal platform for nonlinear pulse dynamics study. Thus, versatile pulse patterns, including dissipative soliton, rectangular pulse, and bright-dark soliton pair, are also demonstrated. Finally, current challenges and future application opportunities of 2D materials-based multi-wavelength ultrafast lasers are presented..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 103002 (2019)
All-optical thermal modulator based on MoS2/WSe2-PVA thin film(invited)
Wang Yifang, Wu Kan, and Chen Jianping
All-optical modulator plays an important role for various all-optical applications in optical communication. An all-optical modulator was mainly investigated based on few-layer molybdenum disulfide (MoS2)-polyvinyl alcohol (PVA) thin films. In addition, an all-optical modulator based on few-layer tungsten disulfide (WSAll-optical modulator plays an important role for various all-optical applications in optical communication. An all-optical modulator was mainly investigated based on few-layer molybdenum disulfide (MoS2)-polyvinyl alcohol (PVA) thin films. In addition, an all-optical modulator based on few-layer tungsten disulfide (WSe2)-polyvinyl alcohol (PVA) thin film was also demonstrated. The modulator was based on polarization interference and the thermo-optic effect of TMDs-PVA thin film. A long-time stable modulated output was obtained. By absorbing the pump at 980 nm, MoS2 or WSe2 generates heat, changes the refractive index of thin film and modifies the polarization of the incident light at 1 550 nm. The obtained thermal all-optical modulator based on MoS2-PVA thin film has a rise time of 526 μs..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 103003 (2019)
Enhanced femtosecond optical pulses compression in highly nonlinear photonic crystal fibers(invited)
Hou Shanglin, Lei Jingli, Wu Qiling, Wang Daobin, Li Xiaoxiao, Wang Huiqin, and Cao Minghua
The soliton-effect compression of femtosecond optical pulses in highly nonlinear silica-core photonic crystal fiber at near-infrared spectrum region(especially at 850 nm) was numerically investigated by full-vector finite element method and split-step Fourier method. A novel SiO2 core photonic crystal fiber with an anoThe soliton-effect compression of femtosecond optical pulses in highly nonlinear silica-core photonic crystal fiber at near-infrared spectrum region(especially at 850 nm) was numerically investigated by full-vector finite element method and split-step Fourier method. A novel SiO2 core photonic crystal fiber with an anomalous group velocity dispersion(β2=-50.698 ps2/km), small higher-order dispersions and high nonlinearity(γ=268.419 1 W-1/km) for efficient soliton-effect compression of femtosecond optical pulses was proposed, the nonlinear Schrodinger equation including higher-order dispersions and Raman scattering was derived. The effect of the Gaussian pulses compression in HN-PCF was numerically investigated by taking account of the fiber length and the soliton order, and the second to fifth orders dispersion were analyzed. The research results show that Q factor and compression factor are maximum at the soliton order of 8. The effect of compression is best when the input pulse′s energy P0=3 357.8 W. By optimizing the geometric and optical parameters of the fiber, the high-quality ultrashort optical pulses with little pedestal energy are obtained.
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Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 103004 (2019)
Effects of spectral modulation on self-similar amplification systems of femtosecond pulses
Li Yuan, Song Huanyu, Zhang Yun, Niu Jia, Liu Bowen, and Hu Minglie
The effects of periodic spectral modulation on self-similar amplification systems of femtosecond pulses were studied by numerical simulation. Femtosecond pulses with spectral modulation amplified in self-similar amplification theoretical model were simulated, by which the impacts of variables of seed pulses, such as arThe effects of periodic spectral modulation on self-similar amplification systems of femtosecond pulses were studied by numerical simulation. Femtosecond pulses with spectral modulation amplified in self-similar amplification theoretical model were simulated, by which the impacts of variables of seed pulses, such as arbitrary phase shift, modulation depth and period, on output results were analyzed. According to the simulation, arbitrary phase shift changes modulated spectral shape, but temporal results of self-similar amplification will not be affected. Besides, large modulation periods make sub-pulses inseparable from main-pulses, disturbing the self-similar amplification process, while small modulation periods bring a longer delay for sub-pulses, making the amplification of main- and sub-pulse independently. This conclusion is still tenable when modulation depth changes..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 103005 (2019)
[in Chinese]
Two-dimensional non-reconstruction compressive sensing adaptive target detection algorithm
Cao Wenhuan, Huang Shucai, Zhao Wei, and Huang Da
A two-dimensional non-reconstruction adaptive threshold algorithm aiming at infrared small target detection was proposed, for the purpose of decreasing the reconstruction algorithms′ negative influence on target detection′s efficiency and results. Aiming at the two-dimentional measurement model which constructed by HadA two-dimensional non-reconstruction adaptive threshold algorithm aiming at infrared small target detection was proposed, for the purpose of decreasing the reconstruction algorithms′ negative influence on target detection′s efficiency and results. Aiming at the two-dimentional measurement model which constructed by Hadamard matrix, the compressive subtract image was analyzed by means of Hadamard′s property in order to decode target′s characteristics in space domain directly. Then the decoded image was detected by utilizing the advanced adaptive threshold method, which avoided the waste of memory space and operation time caused by traditional reconstruction algorithms. Simulation experiment demonstrates that the proposed model can detect the targets on the condition of both single and multiple targets, and has superiorities on detection rate, false alarm rate and operation time than the traditional detection algorithm after reconstruction. It provides a new idea and efficient algorithm for the application of compressive sensing infrared small target detection in engineering..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 126001 (2019)
Simultaneous super-resolution reconstruction based on plane array staring remote sensing images
Yang Rui, Liu Zhaohui, and She Wenji
A group of images for one scene can be obtained by plane array staring remote sensing system. So researchers often use multi-frame image super-resolution reconstruction to produce images with higher spatial resolution. However, most of reports regard super-resolution reconstruction as an isolated part ignoring that geoA group of images for one scene can be obtained by plane array staring remote sensing system. So researchers often use multi-frame image super-resolution reconstruction to produce images with higher spatial resolution. However, most of reports regard super-resolution reconstruction as an isolated part ignoring that geometric parameters of imaging system have the ability to optimize the reconstruction model. Therefore, the influence of attitude angle on resolution changes in different directions was analyzed particularly. Meanwhile, the corresponding anisotropic blur estimation was presented to improve the accuracy of discrimination model. Because of the matching parameter as a significant role in super-resolution reconstruction, for improving the accuracy of the matching parameter estimation and decreasing the global initial matching error caused by the system, the algorithm of simultaneously optimizing super-resolution image and matching parameters based on maximum a posteriori estimation was proposed. This method takes advantage of the useful information of imaging system and improve the robustness of matching parameter by synchronous optimizing. The experimental results demonstrate that the method of our paper is better than existed algorithms in detail information and definition observing by eyes. In addition, the mean square error was reduced 0.3 times, and the information entropy was increased 1.2 in average..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 126002 (2019)
Dynamic range compression and detail enhancement of sea-surface infrared image
Wang Yuanyuan, Zhao Yaohong, Luo Haibo, and Li Fangzhou
Dynamic range compression and detail enhancement are two important issues for effectively displaying high dynamic range infrared(IR) images on standard dynamic range monitors. Sophisticated techniques are required in order to improve the visibility of the details without introducing distortions. To clearly show the higDynamic range compression and detail enhancement are two important issues for effectively displaying high dynamic range infrared(IR) images on standard dynamic range monitors. Sophisticated techniques are required in order to improve the visibility of the details without introducing distortions. To clearly show the highly dynamic infrared image of sea background, a high dynamic range compression and detail enhancement algorithm was presented which was made of three main steps. First, highly dynamic infrared image was enhanced by a multi-directional Laplacian enhancement method based on gradient edge information, and the first order gradient image smoothed was combined with multi-directional Laplacian filtering to enhance images. Second, the dynamic generalized histogram information of the enhanced image was obtained. Finally, the gray level grouping method was used to construct the mapping function, which maps 14 bits intensity in the input image to 8 bits intensity in the output image. As a result, infrared image with low dynamic range was obtained clearly. Experiments on a large number of sea-surface infrared images were conducted. The results verify that the proposed algorithm can improve the contrast of the image, effectively enhance the ship target details, suppress background noise amplification, and avoid the generation of halos. Therefore, the image with high quality was achieved..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 126003 (2019)
Research on space-based high precision algorithm for non-cooperative satellite
Zhang Zixuan, Jia Jianjun, Qiang Jia, Zhang Liang, and Li Jianhua
The space-based non-cooperative target tracking technology could play a crucial part in many aspects of the space application. Currently most well-behaved algorithms were based on video stream. Owing to different working conditions, their tracking precision, speed of operation, warning rate and false alarm rate were diThe space-based non-cooperative target tracking technology could play a crucial part in many aspects of the space application. Currently most well-behaved algorithms were based on video stream. Owing to different working conditions, their tracking precision, speed of operation, warning rate and false alarm rate were dissatisfied with the requirement of space-based satellite tracking systems and missions. Furthermore, the video stream tracking algorithms were too complicated for space-based conditions, where the processors were weaker than those on the ground. To solve these problem, an algorithm based on image correlation, curve fitting, Kalman filter, and SURF algorithm and combined with prediction, tracking and rectification systems was proposed. The algorithm could achieve high speed and high accuracy and be satisfied with the space-based computing environment. Proved by the image simulation experiment and semi-physics simulation, this algorithm could continuously track the target rotated in in-plane arbitrary angle, scaled from 0.4 to 2.1, and handle illumination change. The mean error of image tracking simulation experiment result was lower than 0.9 pixel and frame rate was more than 200 frames per second under most conditions. This algorithm could also deal with image blur, Gaussian noise and salt and pepper noise. Satellite model tracking experiment results showed that the algorithm also had a stably tracking performance for practical satellite model..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 126004 (2019)
Convolutional sparse auto-encoder for image super-resolution reconstruction
Zhang Xiu, Zhou Wei, Duan Zhemin, and Wei Henglu
For the accuracy of feature maps in convolutional sparse coding algorithm, in order to further improve the quality of image super-resolution reconstruction, an image super-resolution(SR) reconstruction algorithm based on convolutional sparse auto-encoder was proposed in this paper. In this algorithm, firstly, the inputFor the accuracy of feature maps in convolutional sparse coding algorithm, in order to further improve the quality of image super-resolution reconstruction, an image super-resolution(SR) reconstruction algorithm based on convolutional sparse auto-encoder was proposed in this paper. In this algorithm, firstly, the input images were pre-trained with sparse auto-encoder for obtaining the feature of LR and HR image; after that, the convolutional neural network trained the corresponding filters and feature mapping function and updated to the optimal solution according to the obtained sparse coefficients; finally, the summation of the convolutions of high-resolution(HR) filters and the corresponding feature maps could reconstruct the HR image. The experimental results show that the peak signal-to-noise ratio(PSNR) of the proposed algorithm is nearly 0.1 dB higher than the CSC algorithm, which improves the quality of reconstructed images..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 126005 (2019)
[in Chinese]
Research development about room temperature terahertz detector array technology with microbolometer structure(invited)
Wang Jun, and Jiang Yadong
Terahertz(THz) detector with thermal sensitive microbolometer structure indicates many prominent features, such as wide band detecting region, large array pixels, high integrated device, real-time imaging, comparing with some other room-temperature THz technologies. Microbolometer structure using VOx thin film as sensiTerahertz(THz) detector with thermal sensitive microbolometer structure indicates many prominent features, such as wide band detecting region, large array pixels, high integrated device, real-time imaging, comparing with some other room-temperature THz technologies. Microbolometer structure using VOx thin film as sensitive material has been successfully fabricated uncooled infrared focal plane array detector, but unsuitable for THz detection for very low THz wave absorption ratio. So some special design should be presented in the microbolometer structure to achieve high performance THz detector. Room-temperature THz technologies and development of microbolometer type THz detector array were introduced in this article briefly, and also the research about THz absorption material or structure in University of Electronic Science and Technology of China was presented in the paper..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 1, 102001 (2019)
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