Proceedings Volume 9796

Selected Papers of the Photoelectronic Technology Committee Conferences held November 2015

Weimin Bao, Yueguang Lv
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Proceedings Volume 9796

Selected Papers of the Photoelectronic Technology Committee Conferences held November 2015

Weimin Bao, Yueguang Lv
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Volume Details

Date Published: 31 March 2016
Contents: 7 Sessions, 105 Papers, 0 Presentations
Conference: Selected Proceedings of the Chinese Society for Optical Engineering Conferences held November 2015 2015
Volume Number: 9796

Table of Contents

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Table of Contents

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  • Front Matter: Volume 9796
  • Atmosphere Optics and Adaptive Optics
  • High-performance Special Optical Film Technology
  • Monitoring, Early Warning, Removal Technology of Space Targets and Debris
  • Novel Navigation Technology
  • Testing and Driving of Laser Fusion Energy Technology
  • UAV Payload Technology
Front Matter: Volume 9796
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Front Matter: Volume 9796
This PDF file contains the front matter associated with SPIE Proceedings Volume 9796 including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.
Atmosphere Optics and Adaptive Optics
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Fine calibration of pyramid wavefront sensor
Yong Liu, Quanquan Mu, Zhaoliang Cao, et al.
The pyramid wavefront sensor (PWFS) is a novel sensor, equipped with superiorities in many aspects comparing with Shack-Hartmann wavefront sensor. The optical system of PWFS is more complicated, and relationships among different elements affect the static aberration of the system, which coupling with the turbulence would impact the sensing accuracy of the sensor. Aiming at improving the sensing accuracy, we analyzed the precise calibration of the system and verified the theory through experiments, which enhanced the closed-loop system’s ability to correct the static turbulence.
The edge detection method of the infrared imagery of the laser spot
Jinxi Che, Jinchun Zhang, Zhongmin Li
In the jamming effectiveness experiments, in which the thermal infrared imager was interfered by the CO2 Laser, in order to evaluate the jamming effect of the thermal infrared imager by the CO2 Laser, it was needed to analyses the obtained infrared imagery of laser spot. Because the laser spot pictures obtained from the thermal infrared imager are irregular, the edge detection is an important process. The image edge is one of the most basic characteristics of the image, and it contains most of the information of the image. Generally, because of the thermal balance effect, the partly temperature of objective is no quite difference; therefore the infrared imagery’s ability of reflecting the local detail of object is obvious week. At the same time, when the information of heat distribution of the thermal imagery was combined with the basic information of target, such as the object size, the relative position of field of view, shape and outline, and so on, the information just has more value. Hence, it is an important step for making image processing to extract the objective edge of the infrared imagery. Meanwhile it is an important part of image processing procedure and it is the premise of many subsequent processing. So as to extract outline information of the target from the original thermal imagery, and overcome the disadvantage, such as the low image contrast of the image and serious noise interference, and so on, the edge of thermal imagery needs detecting and processing. The principles of the Roberts, Sobel, Prewitt and Canny operator were analyzed, and then they were used to making edge detection on the thermal imageries of laser spot, which were obtained from the jamming effect experiments of CO2 laser jamming the thermal infrared imager. On the basis of the detection result, their performances were compared. At the end, the characteristics of the operators were summarized, which provide reference for the choice of edge detection operators in thermal imagery processing in future.
Influence of atmospheric turbulence on optical measurement: a case report and review of literature
When videogammetry (optical measurement) was carried outdoor or under cruel indoor circumstance, the results would be inevitably affected by the atmosphere turbulence. As a result, the precision of surveying was destroyed. The field of air turbulence’s impact on optical measurement was neglected by scholars for a long time, the achievements massed about laser optics and optical communications. The mostly adapted method was noise filtration when the pixel wandering could not be rejected in engineering application, which got little improvement on usual conditions. The principle of influence under atmospheric turbulence on optical measurement is presented in this paper. And experiments data and applications are carried out to announce the impact of atmospheric turbulence. Combining with relevant researches, some essential issues and expectations of the atmospheric turbulence research are proposed.
Temperature measurement of wood flame based on the double line method of atomic emission spectra
Xiaojian Hao, Zhenhua Liu, Tao Sang
Aimed at the testing requirement of the transient high temperature in explosion field and the bore of barrel weapon, the temperature measurement system of double line of atomic emission spectrum was designed, the method of flame spectrum testing system were used for experimental analysis. The experimental study of wood burning spectra was done with flame spectrum testing system. The measured spectra contained atomic emission spectra of the elements K, Na, and the excitation ease of two kinds atomic emission spectra was analyzed. The temperature was calculated with two spectral lines of K I 766.5nm and 769.9nm. The results show that, compared with Na, the excitation temperature of K atomic emission spectra is lower. By double line method, the temperature of wood burning is 1040K, and error is 3.7%.
Numerical simulation research on sodium laser beacon imagings through the atmosphere turbulence
Xiangyuan Liu, Xianmei Qian, Suimeng Zhang, et al.
Based on the relative intensity distributions of Sodium Laser Beacon (SLB) and analysis of the on-axis imaging of incoherent light, considering the effects of atmospheric turbulence and the changes of telescope receiving diameter on the short-exposure SLB imagings on the focal plane, imagings of an extended source SLB are simulated under the three atmospheric turbulence models. Results indicate that sharpness and peak strehl ratio of SLB imagings increase but sharpness radius decrease with the decrease of atmosphere turbulence strengths. Moreover, the changes of telescope diameter from 3.0m to 1.5m cause the decrease of sharpness and peak strehl ratio but the increase of sharpness radius.
Influence of determination of reference position of image on rocket take-off drift
Shuhua Cui, Jun Liu, Si Shen, et al.
Mathematical analysis model for influence of reference position deviation on carrier rocket take-off drift has been made to tackle the issue on determination of reference position of reticule for optical tracking and measurement of video image in aerospace test range and the variation in rocket take-off drift due to reference position deviation has been subjected to quantitative analysis based on angular error of tracking and lateral error of measuring point as a result of deviation of reference position of reticule cross. The method serves as technical support to quality analysis of rocket take-off deviation measurement data and improvement in data processing precision for carrier rocket take-off drift.
The validation and comparison of the GOCI aerosol optical thickness products: a case study of Tianjin 8.12
Lingling Yao, Xiaoyu Zhang, Hui Yu, et al.
COMSGOCI (Geostationary Ocean Color Imager) is the first geostationary ocean color satellite in the world launched by South Korea in June 2010, which includes eight bands from the visible to the infrared band. GOCI aerosol optical thickness (AOT) at 555nm was retrieved by atmospheric radiative transfer model based on two-stream approximation algorithm. Due to GOCI without near infrared band and has a high solar elevation angle, solar zenith angle must be recalibrated to solve the earth system albedo, and the surface reflectance solved by quack atmospheric correction and recalculated backward scatter coefficient. Evaluation of GOCIAOT with AERONET measurements showed that the average error becomes 0.107 from the original 0.393, that means GOCI aerosol optical thickness can be more accurately with the advanced two-stream approximation. Taking the eastern China in 3 and 4 December 2013 for example, comparing the GOCIAOT at 555nm, MODISAOT retrievals at 550nm, NPPAOT at 550nm and AERONET data products indicated that: take the AERONET data as reference, the error of three kinds of satellite data can be ordered as following: MODISAOT< GOCIAOT< NPPAOT and the GOCI-MODIS shows a bias of 0.02917 with the GOCI-NPP. GOCIAOT is 0.05714 generally bigger than that of MODISAOT. NPP-GOCI deviation is 0.10253. The deficiency of MODIS is its low spatial resolution and the high concentration of AOT will be mistaken for a cloud area. However, GOCI can well reflect the concentration and distribution of aerosols. Therefore, GOGI can provide real-time dynamic monitoring on China Eastern atmospheric environment and the accurate time event information of haze for each process can be obtained. Finally, applied GOCI to the "8.12 Tianjin bombings" and to monitor the migration and dispersion of pollutant.
Cirrus cloud properties measurement using lidar in Beijing
Chengli Ji, Zongming Tao, Shunxing Hu, et al.
Cirrus cloud has an important effect on the radiation balance between the earth’s surface and the atmosphere. The vertical structures, optical depth and effective lidar ratio of cirrus cloud detected by Mie scattering-polarization-Raman lidar system in Beijing from April 11 to December 31, 2012 are analyzed. The results show that the cloud height in Beijing is lower in spring and higher in autumn, with a mean value of about 8km. The mean of cloud thickness is 0.74km. The mean of optical depth is 0.092, and most observed cirrus cloud is thin while optical depth is less than 0.3. The effective lidar ratio of cirrus is lower in summer and higher in winter, inversely related to local temperature, with a mean value of 32.29Sr.
Infrared thermal wave non-destructive detection for the internal structure of metal Buddha head
He-Nan Zhang, Zhen-Wei Zhang, Yong Lei, et al.
Objective This paper depicts a testing technology of nondestructive infrared imaging for acquiring internal structure information of metal Buddha head. Methods applying active infrared thermal imaging nondestructive testing technology Results Data which was collected by IR camera was processed, the typical time thermograph and the curve of logarithmic temperature-time can be. get information of relative thickness in metal Buddha face. Conclusion Infrared thermal imaging technology can be detect the inside information of metal Buddha head . It is feasible to conserve heritage in infrared imaging method.
Photoelectric radar servo control system based on ARM+FPGA
Kaixuan Wu, Yue Zhang, Yeqiu Li, et al.
In order to get smaller, faster, and more responsive requirements of the photoelectric radar servo control system. We propose a set of core ARM + FPGA architecture servo controller. Parallel processing capability of FPGA to be used for the encoder feedback data, PWM carrier modulation, A, B code decoding processing and so on; Utilizing the advantage of imaging design in ARM Embedded systems achieves high-speed implementation of the PID algorithm. After the actual experiment, the closed-loop speed of response of the system cycles up to 2000 times/s, in the case of excellent precision turntable shaft, using a PID algorithm to achieve the servo position control with the accuracy of + -1 encoder input code. Firstly, This article carry on in-depth study of the embedded servo control system hardware to determine the ARM and FPGA chip as the main chip with systems based on a pre-measured target required to achieve performance requirements, this article based on ARM chip used Samsung S3C2440 chip of ARM7 architecture , the FPGA chip is chosen xilinx's XC3S400 . ARM and FPGA communicate by using SPI bus, the advantage of using SPI bus is saving a lot of pins for easy system upgrades required thereafter. The system gets the speed datas through the photoelectric-encoder that transports the datas to the FPGA, Then the system transmits the datas through the FPGA to ARM, transforms speed datas into the corresponding position and velocity data in a timely manner, prepares the corresponding PWM wave to control motor rotation by making comparison between the position data and the velocity data setted in advance . According to the system requirements to draw the schematics of the photoelectric radar servo control system and PCB board to produce specially. Secondly, using PID algorithm to control the servo system, the datas of speed obtained from photoelectric-encoder is calculated position data and speed data via high-speed digital PID algorithm and coordinate models. Finally, a large number of experiments verify the reliability of embedded servo control system’s functions, the stability of the program and the stability of the hardware circuit. Meanwhile, the system can also achieve the satisfactory of user experience, to achieve a multi-mode motion, real-time motion status monitoring, online system parameter changes and other convenient features.
Application of fiber laser in time constant measurement of thin wire thermal resistor
Junwei Zhao M.D., Shuanglian Feng, Zhigang Zhang, et al.
Measuring principle of time constant for thin wire thermal resistor was put forward. An 1.07μm fiber laser was used to output a rectangle laser pulse with edges of several tens microns and width of 100ms, and the thermal resistor under test was shined by the laser. As a result, the temperature of the thermal resistor rose and gradually went up to a fixed level with the irradiation. And then the thermal resistor’s temperature dropped and gradually went down to the room temperature with the laser powered off. Time constant of the thermal resistor could be obtained by means of measuring the temperature variation of the thermal resistor due to the laser pulse. A device was designed and experiments were carried out, the time constants of three commonly used thin wire thermal resistors were measured.
Laser cool and trap trace noble atoms
Mingdong Wang, Yanji Hong, Gaoping Feng
Laser can be used to cool and manipulate neutron atoms via momentum exchange between photons and atoms. Laser cooling and trapping is well established on alkali, alkali earth, and noble gas elements. Noble gases, with stable physical and chemical properties, no reactions with other elements, have great potential uses in cold collision, spectroscopy measurement, photo-association, atom optics, etc. However, trapping noble gas atoms is generally more difficult because of the lack of suitable UV lasers. Some of these problems will be overcome with future advances in UV laser technology. Excited by electron collisions, noble gas can reach the long life metastable state for the use of laser decelerating, focusing and trapping. In this paper some main methods which are used to achieve cooling and trapping metastable noble gas atoms are discussed.
Fluctuations of light intensity scattered from multiple glints in atmospheric turbulence
Liguo Wang, Yaqing Li, Ming Gao, et al.
As targets in space are usually very far from the ground, some targets containing smooth reflecting components can be seen to be composed of a single or multiple glints when they are detected by a Lidar (laser radar) system located on the ground. The received intensity of the detector fluctuates, which caused significant noise on the system, for two reasons. One is the randomness of positions of the glints and the other is the perturbations of the atmospheric turbulence. The formulation of the scintillation index of the reflected intensity is derived by using incoherent superposition of the reflected field. The results show that the scintillation index can be divided into two parts, corresponding to the two sources that cause the intensity fluctuations. The results show that the target composed by multiple glints has two different effects on the fluctuation of the reflected intensity, one is the amplification effect of the incoherent superposition, and the other is some similar aperture averaging effect.
Analysis on optical characters of atmosphere of sea of China
Chengliang Ge, Kai Zhang, Youguang Guan, et al.
In the field of laser applications, it needs to know the optical characters of sea’s atmosphere. By referring, measuring and theoretically studying, the optical characters of atmosphere of China’s sea are studied herein. These optical characters are mainly about Cn2, and visibility, and so on. And the differences between sea and earth are compared with their optical characters. Then, some basic and important conclusions are made.
A review of large aperture Schlieren photography technique
Schlieren photography is a visual process to display the flow of fluids of varying density. It is widely used in wind tunnel tests to photograph the flow of air around objects. To achieve schlieren images with high sensitivity and high resolution, and satisfy the requirements of the large-scale wind tunnel tests, it is urgent to develop schlieren photographers with large aperture primary mirrors. However, the application of large aperture primary mirrors may bring many challenges in the design of the schlieren system. First, the surface figure of large aperture primary mirrors is difficult to control so that the support structure may need more strategical design. Second, because the schlieren system works under some severe environments of the wind tunnel test including the air disturbance, wind-induced ground vibration and high ambient pressure, it has to withstand serious instability risks to ensure a good schlieren image quality. In this work, the current status of the development in the large aperture schlieren systems is reviewed. Several advanced methods, for example, active damping control technique, focal spot monitoring technique, 18-points whilffletree support technique, etc.., are introduced to deal with the challenges of the large aperture schlieren system. This work aims at improving the technical development of large aperture schlieren photographer, which may contribute to the acquisition of the high sensitive and high resolution schlieren images and the improvement of the testing capability in wind tunnel experiments.
Lucky region imaging based on front and back defocus images comparison
Lucky imaging technology is widely applied in astronomical imaging system because of its low cost and good performance. However, the probability of capturing an excellent lucky image is low, especially for a large aperture telescope. Thus a method of adaptive image partition is proposed in this paper to extract any lucky part of an image so as to increase the probability of obtaining the lucky image. This system is comprised of a telescope and three cameras running synchronously at the image plane, the front defocus plane and the back defocus plane respectively. Two out-focus cameras have the same defocus distance. Our algorithm of selecting each lucky part of the space object picture, which is influenced little by atmosphere turbulence, is based on the difference between pictures obtained by the front and the back defocus cameras. Then image stitching is used to obtain the entire sharp picture.
Comparison and analysis of atmospheric optical turbulence in coast and over sea
Jun Cai, Xiaoqing Wu, Yiping Yang
Observation of meteorological parameters in coast and over sea surface layer will be conducive to understand the interaction between ocean and atmosphere, as well as the mechanism that ocean impacts on climate. Compared with the coast, it is more difficult to measure the atmospheric optical turbulence over sea, which includes measurement error caused by the instability of observation platform, instrument damage caused by poor environment and accuracy of measurement caused by the known and unknown factors, and so on. Conventional meteorological parameters and atmospheric optical turbulence in coast and over sea were observed by instruments equipped on the Marine Meteorological Science Experiment Base at Bohe and characteristics of atmospheric optical turbulence in this region were analyzed. By using temperature, humidity and wind speed, the atmospheric refractive-index structure constant in coast were estimated, and then compared with measured values, which verified the feasibility of this method.
Angular anisoplanatism of a focused beam using beacons over horizontal path
The performance of the achieve laser beam propagation through atmospheric turbulence with adaptive optics is degraded by the fact that the wavefront aberrations difference. This error is only include the angular anisoplanatism when there is separation between the achieve laser beam and beacon. In the paper we derive an analytic expression for the effective angular anisoplanatism as a function of displacement angular when the turbulence profile is uniform. It shows that the effective angular anisoplanatism becomes weaker as the diameter of laser beams and the Fried transverse coherence length increase. We report results from field experiments that the effective angular anisoplanatism of a focused beam over horizontal path. It is found that measured and theoretical results are consistent. The effective wavefront variance increases with the strength of atmospheric turbulence and the angular displacement. And the constant phase of angular anisoplanatism has no effect on the Strehl ratio of the beam.
Tunable RF photonic phase shifter based on optical DSB modulation and FBG filtering
Yongfeng Wei, Shanguo Huang, Kai Sun, et al.
A broadband RF photonic phase shifter that can achieve the tunable phase shift with little RF amplitude variation is presented. It is based on homodyne mixing technique. The beating between phase-modulated optical carrier and the sidebands can generate RF signal with desired phase shift. Results show the RF phase shifter can achieve a continuous phase shift with low amplitude variation.
Pattern characteristics of laser beams in a ground-to-satellite optical link
Guangsen Ren, Qianrong Chen, Yongwang Hao, et al.
Due to influence of atmosphere turbulence, distribution characteristics of laser speckles vary with propagation distances. In this paper, numerical calculation using a multiple-phase screen method is performed to simulate the propagation of laser beam in the turbulence. The distributions of intensity at different distances are calculated. A characteristic factor σ 2 is proposed to quantify the degree of turbulence induced intensity spatial fluctuation compared with the same beam propagating in vacuum. The results show that, at the same distance, mean σ 2 of the beam propagating perpendicularly is smaller than the beam propagating horizontally. For a perpendicularly transmitted Gaussian beam, mean σ 2 decreases gradually after it reaches its maximum value, and tends to be stable if the propagation distance is long enough.
Numerical analysis of wavefront measurement characteristics by using plenoptic camera
Yang Lv, Haotong Ma, Xuanzhe Zhang, et al.
To take advantage of the large-diameter telescope for high-resolution imaging of extended targets, it is necessary to detect and compensate the wave-front aberrations induced by atmospheric turbulence. Data recorded by Plenoptic cameras can be used to extract the wave-front phases associated to the atmospheric turbulence in an astronomical observation. In order to recover the wave-front phase tomographically, a method of completing the large Field Of View (FOV), multi-perspective wave-front detection simultaneously is urgently demanded, and it is plenoptic camera that possesses this unique advantage. Our paper focuses more on the capability of plenoptic camera to extract the wave-front from different perspectives simultaneously. In this paper, we built up the corresponding theoretical model and simulation system to discuss wave-front measurement characteristics utilizing plenoptic camera as wave-front sensor. And we evaluated the performance of plenoptic camera with different types of wave-front aberration corresponding to the occasions of applications. In the last, we performed the multi-perspective wave-front sensing employing plenoptic camera as wave-front sensor in the simulation. Our research of wave-front measurement characteristics employing plenoptic camera is helpful to select and design the parameters of a plenoptic camera, when utilizing which as multi-perspective and large FOV wave-front sensor, which is expected to solve the problem of large FOV wave-front detection, and can be used for AO in giant telescopes.
High-performance Special Optical Film Technology
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Influence of deposition parameters on residual stress of YbF3 thin film
Yao-ping Zhang, Jun-qi Fan, Guo-yun Long
YbF3 was proposed as a substitute for ThF4 in anti-reflection or reflection coatings for the infrared range, and the residual stress of YbF3 thin film using APS plasma ion assisted deposition(PIAD) was studied. From the results, we found the anode voltage of PIAD has a large effect on the residual stress of YbF3 thin film, and the refractive index of YbF3 produced with PIAD was higher than without it, with a possible reason close to packing density. Finally, we produced multi-layer reflection coating on a 260mm diameter mono-crystalline silicon substrate. Its surface contour was approximately 0.240λ (λ=632.8nm), and the absorption was lower than 200ppm, which can satisfy the practical requirement.
Study on the optical-character of the ZnO film under the 60Co irradiation
Hui Wang, Zaikui Xiang, Lei Wang, et al.
The fused silica have being used as the lens on the spacecraft ,In order to enhanced the optical character, the film works .We studied the changing of the ZnO film on the fused silica under the radiation of the 60Co irradiation which is close to the actual-condition. The anti- irradiation character under the 60Co γ-ray of the is ZnO film not good while the heat-treatment of the film leading to the optimizing of the physical-character under the radiation of the 60Co γ-ray. The cracking of the film is obvious being irradiation.
Research of absolute testing based on N-position rotations
The full-aperture and full-frequency absolute surfaces of optical flats are of great significant for industrial applications but hard to achieve. To measure them simultaneously, Kuechel proposed an absolute testing based on N-position rotations by adding a set of measurement data of N-position rotations, in comparison to the traditional four measurements. Algorithm simulation and absolute detection experiments have been conducted before, however, the influence of rotation angle error has not been analyzed, and the full-aperture contrast experiments have not been conducted. In this paper, the influence of rotation angle error was analyzed, and the measurement result is within acceptable range even when the angle error reaches 1°. Moreover, to verify the accuracy of this method, full-aperture contrast experiments were proposed innovatively besides the two linear profiles contrast experiments. The contrast experiments prove the accuracy of the full-aperture absolute measured results, other than the accuracy of the two linear profiles results.
Hexagonal GaN films with micron thickness fabricated by nitridation of Mg doped-Ga2O3 crystals
Xiao-Jun Cui, Liang-Ling Wang
The GaN film with micron thickness was fabricated on the (100) cleavage plane of β-Ga2O3 single crystal by nitridation with NH3 gas flow rate of 400 sccm at 950°C for 10h. The GaN film has small cavities, suggesting that the growth mechanism is three dimensional growth mode like Volmer-Weber model. The thickness of GaN film formed by nitridation is about 1.18 μm. There are GaN (002) and (004) diffraction peaks in the XRD spectra, indicating that the epilayer has a strong c-axis preferred orientation. The photoluminescence spectra, transmittance spectra and Raman spectra of the GaN film were investigated.
Second harmonic generation of Q-switched Ho:LuAG laser with KTP
Dezhao Zhou, Helong Wang, Baoquan Yao, et al.
The second harmonic generation (SHG) of Q-switched Ho:LuAG laser in a KTP crystal was demonstrated. Under the Type II phase matching conditions, we obtained the maximum second harmonic energy per pulse of 6.82μJ and the minimum pulse width of 67.3ns at 1050.30nm in the fundamental wavelength of 2100.65nm, corresponding to a peak power of about 0.101kW. By inserting a 0.05mm-thickness YAG uncoated etalon, the maximum second harmonic energy per pulse of 4.83μJ and the minimum pulse width of 70.6ns at 1046.89nm was obtained in the fundamental wavelength of 2093.86nm, corresponding to a peak power of about 0.068kW.
New ITF measure method based on fringes
With the unprecedented developments of the intense laser and aerospace projects', the interferometer is widely used in detecting middle frequency indicators of the optical elements, which put forward very high request towards the interferometer system transfer function (ITF). Conventionally, the ITF is measured by comparing the power spectra of known phase objects such as high-quality phase step. However, the fabrication of phase step is complex and high-cost, especially in the measurement of large-aperture interferometer. In this paper, a new fringe method is proposed to measure the ITF without additional objects. The frequency was changed by adjusting the number of fringes, and the normalized transfer function value was measured at different frequencies. The ITF value measured by fringe method was consistent with the traditional phase step method, which confirms the feasibility of proposed method. Moreover, the measurement error caused by defocus was analyzed. The proposed method does not require the preparation of a step artifact, which greatly reduces the test cost, and is of great significance to the ITF measurement of large aperture interferometer.
Luminescent properties study of Lu2SiO5:(Ce3+,Tb3+) optical films prepared by sol-gel method
Jianjun Xie, Fangyuan Zhang, Siqing Shen, et al.
Re3+ (Re= Ce3+, Tb3+) doped and co-doped lutetium oxyorthosilicate Lu2SiO5 (LSO) optical films were prepared by Pechini sol-gel method combined with spin-coating technique. The luminescence properties were analyzed by measuring the excitation and emission spectra in the UV. The results indicated that the Ce3+ excitation bands in the region from 220 to 360nm attributed to the 4f−5d transition of Ce3+. Tb3+ excitation bands in the region from 220 to 250nm were due to the 4f−5d transitions of Tb3+. The emission spectra showed the characteristic emission of 5D12FJ (J=7/2,5/2) transition for Ce3+5 and D47FJ (J = 3, 4, 5, 6) transition for Tb3+. Energy transfer from Ce3+ to Tb3+ was observed and discussed.
Study on the mechanical property of polyimide film in space radiation environments
Zicai Shen, Yongqiang Mu, Yigang Ding, et al.
Polyimide films are widely used in spacecraft, but their mechanical properties would degrade in space environments, such as electron, proton, near ultraviolet or far ultraviolet, etc. The mechanical property and mechanism of polyimide film in electron, proton, near ultraviolet and far ultraviolet was studied by Φ800 combined space radiation test facility of Beijing Institute of Space Environment Engineering (BISSE. Rupture elongation of Kapton film decrease with the increase of the tensile deformation rate. The tensile strength and the rupture elongation of Kapton film decrease with the increase of electron and proton radiation, while tensile strength and the rupture elongation of Kapton film decrease firstly and then increase with near ultraviolet and far ultraviolet.
A study on the preparation of diamond like carbon film and its electrodes
Diamond-like carbon (DLC) films have attracted much attention because of their excellent performance; however, the low anti-laser damage ability of such films seriously restricts their applicability. To overcome this problem, applying the bias field to the DLC film could slow down the DLC film graphitization process and improve the LIDT of the DLC film. Results showed that the longitudinal electric field could decrease the sp3 hybridization to sp2 hybridization, prevent the formation of sp2 clusters. in this study, Unbalanced magnetron sputtering (UBMS) was used to deposit a diamond-like carbon (DLC) film on Si substrates. The refractive index and extinction coefficient of the DLC films were measured using elliptical polarization spectrometer. The transmittance and the surface roughness of DLC films were examined using optical microscopy, SEM, AFM and Raman spectroscopy. Ti electrodes were deposited on DLC films directly, forming a transverse and longitudinal bias field on films’ surfaces. The 3D electrodes morphology of the DLC film was observed. The electrode thickness was measured by a white-light interferometer, and the average thickness of the electrodes was 325.90 nm. The surface roughness of the electrodes was tested using the Talysurf CCI 2000 noncontact surface-measuring instrument, and the average roughness of the electrodes was 0.50 nm. The electrodes have good Ohmic contact and little thermal stress, and it can be used to form a parallel electric field.
The high precision control of the satellites formation for diffraction imaging
Guang Yang, Liang He, Ting Song, et al.
To satisfy need of high resolution observation from space. This article elaborates a method of high precision spacecraft formation control based on file diffraction theory. Improving the spacecraft control accuracy to millimeter is a challenge. With the method in this article this challenge can be solved. The algorithm in this article concerning the vibration of spacecraft and based on dynamic modeling of even relative quaternion theory deduced a method of attitude and orbit integrated control. Using this control algorithm to simulation can get the result that it can make the spacecraft integrate formation control as the technical basis of space high resolution observation.
Finite element analysis of a variable optical attenuator based on s-shape polymer waveguide
Jing Wan, Lingxun Wu, Fenglan Xue, et al.
A variable optical attenuator (VOA) based on S-shape polymer waveguide is demonstrated at the wavelength λ = 1.55 micron. The VOA consists of straight input and output waveguides, an S-shape waveguide and a pair of deposited electrodes. The cladding material of S waveguide is Poly (methyl methacrylate/disperse red 1) (PMMA/DR1) and the core material of S waveguide is SiON. The refractive index of the polymer cladding at S waveguide is modified by the applied electric voltage. Light scatters at the S waveguide and the VOA has large energy loss in the original state at voltage-off. In the voltage-on state, the refractive index of the polymer of the S waveguide reduces, and energy loss changes as the voltage increases. The attenuation of the VOA can be controled and adjusted by the applied voltage. The beam propagation method(BPM) and finite element analysis are employed to simulate and analyse the VOA. The results show that the VOA has large variable attenuation range of 45.2dB and low insertion loss of 0.8dB.
Laser beam riding guided system principle and design research
Zhou Qu, Yi Jin, Zhou Xu, et al.
With the development of science and technology, precision-strike weapons has been considered to be important for winning victory in military field. Laser guidance is a major method to execute precision-strike in modern warfare. At present, the problems of primary stage of Laser guidance has been solved with endeavors of countries. Several technical aspects of laser-beam riding guided system have been mature, such as atmosphere penetration of laser beam, clutter inhibition on ground, laser irradiator, encoding and decoding of laser beam. Further, laser beam quality, equal output power and atmospheric transmission properties are qualified for warfare situation. Riding guidance instrument is a crucial element of Laser-beam riding guided system, and is also a vital element of airborne, vehicle-mounted and individual weapon. The optical system mainly consist of sighting module and laser-beam guided module. Photoelectric detector is the most important sensing device of seeker, and also the key to acquire the coordinate information of target space. Currently, in consideration of the 1.06 u m of wavelength applied in all the semi-active laser guided weapons systems, lithium drifting silicon photodiode which is sensitive to 1.06 u m of wavelength is used in photoelectric detector. Compared to Solid and gas laser, diode laser has many merits such as small volume, simple construction, light weight, long life, low lost and easy modulation. This article introduced the composition and operating principle of Laser-beam riding guided system based on 980 nm diode laser, and made a analysis of key technology; for instance, laser irradiator, modulating disk of component, laser zooming system. Through the use of laser diode, Laser-beam riding guided system is likely to have smaller shape and very light.
Study on methenamine detection in starch products through SERS technology
Using silver sol as a strengthened base, this paper concludes that l0ppb-0.1ppb methenamine aqueous solution has a better signal in 1052cm-1 Raman feature. And the lower limit of the aqueous solution is about 0.1ppb. Adding corresponding amount methenamine in vermicelli sample, the lower limit is about 10ppm. This is a safest and pollution-free detection process. Furthermore, the pretreatment process is simple, which will be finished in 20 minutes. Hence, it is better than other detection methods. SERS technology provides a simple, rapid and efficient detection method for field measurement and real time detection modulating disk of component, laser zooming system. Through the use of laser diode, Laser-beam riding guided system is likely to have smaller shape and very light.
Design and manufacture of a bandpass filter with high transmittance and steep edge on both sides
Ruisheng Wang, Shaobo Lü, Xiaojun Yin, et al.
By using Nb2O5 and SiO2 as the coating material, a 152 layers (12 cavities) bandpass film stack with steep edge on both sides was designed. Multiple thickness control methods, including direct optical monitoring control and time control were used in coating strategy. To confirm the feasibility of this coating strategy, a process simulation was performed using Simulator software, and the simulation result indicated that relative thickness errors for all layers were less than ±0.1%. A bandpass filter with this film stack on one side was manufactured by using a plasma assisted reactive magnetic sputtering coating machine. The measuring result shows that the peak transmittance of the filter (without AR on backside) is up to 95.4%, and the steepness of both blocking slope are less than λ/100.
Study on monolithically integration miniaturized spectral imager by Fabry-Perot with Bragg stack
Shuyang Liu, Tao Zhou, Xiaodong Jia, et al.
To break the limitation of the traditional spectral analysis system in low speed, high cost and huge size, this paper presents a CMOS-based monolithically miniaturized spectral system whose core component is the spectral imager. The idea of the spectral imager is to fabricate a spectral filter on top of the traditional CMOS imager. This paper designed a FP thin film filter consisted of Bragg stack as a mirror while both the material and the process is compatible with the CMOS imager fabrication. By the simulation, the filter is able to achieve a 2nm spectral resolution, which is a proof for the feasibility of the miniaturized spectral analysis system.
Preparation and properties of all-solid-state inorganic thin film glass/ITO/WO3/LiNbO3/NiOx/ITO electrochromic device
Zhonghou Wu, Xungang Diao, Guobo Dong
The all-thin-film inorganic electrochromic device (ECD) with LiNbO3 as the ion conductor layer was prepared. The ECD was fabricated monolithically in a same vacuum chamber layer by layer using DC reactive sputtering for WO3, NiOx and ITO, and radio frequency (RF) sputtering for LiNbO3. The properties and performance of WO3 thin film and the ECD were studied through X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet-visible spectrometry. WO3 thin film has more than 60% optical modulation with porous amorphous structure. The visible transmittance modulation of the ECD is more than 65%, and the response time of coloring and bleaching are 45 s and 25 s, respectively.
Monitoring, Early Warning, Removal Technology of Space Targets and Debris
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The visible light imaging detection performance of spaced target
Zhaofei Hou, Wei Zhao, Feng Yu
According to the radiation intensity of the spaced-target, the SNR and detection distance of the spaced target of visible light has been study and analyzed. The relationship between SNR, detection distance and the size of the spaced-target, the reflectance, observed phase angle, as well as the entrance pupil area has been obtained. The specific formula of the detection distance of the spaced-target of detection of the visible light detection system is given. And key indicators that impact the detection distance of spaced target of visible light have been analyzed. The study provides a theoretical basis for the performance of the future space-target detection system.
Direct absorption spectroscopy sensor for temperature and H2O concentration of flat flame burner
Jin-hu Duan, Xing Jin, Guang-yu Wang, et al.
A tunable diode laser absorption sensor, based on direct absorption spectroscopy and time division multiplexing scheme, was developed to measure H2O concentration and temperature of flat flame burner. At the height of 15mm from the furnace surface, temperature and concentration were measured at different equivalence ratios. Then the distance between the laser and the furnace surface was changed while the equivalence ratio was fixed at 1 and experiments were performed to measure temperature and H2O concentration at every height. At last flame temperatures and H2O concentrations were obtained by simulation and computational analysis and these combustion parameters were compared with the reference. The results showed that the experimental results were in accordance with the reference values. Temperature errors were less than 4% and H2O component concentration errors were less than 5%and both of them reached their maximum when the equivalent ratio was set at 1. The temperature and H2O concentration increased with the height from furnace surface to laser when it varied from 3mm to 9mm and it decreased when it varied from 9mm to 30mm and they reached their maximum at the height of 9mm. Keywords: tunable diode laser, direct absorption spectroscopy
Design method of combined protective against space environmental effects on spacecraft
Zicai Shen, Zizheng Gong, Yigang Ding, et al.
During its projected extended stay in LEO, spacecraft will encounter many environmental factors including energetic particles, ultraviolet radiation, atomic oxygen, and space debris and meteoroids, together with some induced environments such as contamination and discharging. These space environments and their effects have threat to the reliability and lifetime of spacecraft. So, it is important to give a combined design against the threat from space environments and their effects. The space environments and effects are reviewed in this paper firstly. Secondly, the design process and method against space environments are discussed. At last, some advices about protective structure and materials are proposed.
Bands selection and classification of hyperspectral images based on hybrid kernels SVM by evolutionary algorithm
Yan-Yan Hu, Dong-Sheng Li
The hyperspectral images(HSI) consist of many closely spaced bands carrying the most object information. While due to its high dimensionality and high volume nature, it is hard to get satisfactory classification performance. In order to reduce HSI data dimensionality preparation for high classification accuracy, it is proposed to combine a band selection method of artificial immune systems (AIS) with a hybrid kernels support vector machine (SVM-HK) algorithm. In fact, after comparing different kernels for hyperspectral analysis, the approach mixed radial basis function kernel (RBF-K) with sigmoid kernel (Sig-K) and applied the optimized hybrid kernels in SVM classifiers. Then the SVM-HK algorithm used to induce the bands selection of an improved version of AIS. The AIS was composed of clonal selection and elite antibody mutation, including evaluation process with optional index factor (OIF). Experimental classification performance was on a San Diego Naval Base acquired by AVIRIS, the HRS dataset shows that the method is able to efficiently achieve bands redundancy removal while outperforming the traditional SVM classifier.
Analysis and discussion about the antenna networking structure of three concentric spheres
Yan An, Yalin Zhang, Yiwu Zhao, et al.
In order to break through the laser communication technology of one point to multipoint, which is the difficult problems for laser communication. The networking solutions of the antenna structure of three concentric spheres are proposed. Being with the advantages of simple structure, small size and light weight, the antenna structure of three concentric spheres can be applied to short-distance space laser communication. The feasibility of the system can be realized from two aspects, the analysis of link and the analysis of the precision index. On this basis, the whole optical system can be determined by the corresponding optical system design. Under the condition of permitting of link energy, the optical system of antenna structure of three concentric spheres with mobile field azimuth angle of 120°and the pitching angle of 20°is completed. The parameters can meet the requirements in the subsystem of the communication receiving optical path, the communication transmitting optical path and the communication tracking optical system. The results indicate that the antenna structure of three concentric spheres can be applied to the laser communication networking under the short-distance space.
Design and simulation of satellite attitude control system based on Simulink and VR
Yang Zhang, Qingbo Gan, Jingshu Kang
In order to research satellite attitude control system design and visual simulation, the simulation framework of satellite dynamics and attitude control using Simulink were established. The design of satellite earth-oriented control system based on quaternion feedback was completed. The 3D scene based on VR was created and models in the scene were driven by simulation data of Simulink. By coordinate transformation. successful observing the scene in inertial coordinate system, orbit coordinate system and body coordinate system. The result shows that application of simulation method of Simulink combined with VR in the design of satellite attitude control system field, has the advantages of high confidence level, hard real-time property, multi-perspective and multi-coordinate system observing the scene, and improves the comprehensibility and accuracy of the design.
New method of space debris cleaning based on light negative force: tractor laser
Qiongge Sun, Long Gao, Chen Li
This paper presents a new way of space debris removal and protection, that is, using tractor laser, which based on light negative force, to achieve space debris cleaning and shielded. Tractor laser is traceable from the theory of optical tweezers, accompanied with non-diffraction beam. These kind of optical beams have the force named negative force pointing to optical source, this will bring the object along the trajectory of laser beam moving to the optical source. The negative force leads to the new method to convey and sampling the space micro-objects. In this paper, the application of tractor laser in the space debris collection and protection of 1cm is studied. The application of the several tractor beams in the space debris and sample collection is discussed. The proposed method can reduce the requirements of the laser to the satellite platform, and realize the collection of space debris, make the establishment of the space garbage station possible, and help to study the spatial non contact sample transmission and reduce the risk of space missions.
Complex morphology small targets detection based on spatial-temporal sparse recovery in infrared surveillance system
Miao Li, Qi Wang, Jun Li, et al.
Complex morphology target, which is size-varying and shape-varying, is a great challenge for infrared surveillance system. In this paper, temporal low-rank and sparse decomposition model and spatial low-rank and sparse decomposition model are designed respectively. Subsequently, a joint spatial-temporal detection method of complex morphology target is presented. Firstly, initial background subspace is obtained based on training sequence which does not contain infrared target. Secondly, temporal target image is recovered by l1 minimization after projecting orthogonal to background subspace. Thirdly, original image is decomposed into background image and spatial target image using inexact augmented Lagrange multipliers approach. Fourthly, by fusing the two target images, the possible small targets can be extracted well. Finally, background subspace is updated based on incremental singular value decomposition algorithm. The experimental results show that our method is effective and robust to detect complex morphology infrared targets. In particular, the proposed method can extract targets accurately, which is important for target recognition.
An optimal trajectory design for debris deorbiting
Gaoxiang Ouyang, Xin Dong, Xin Li, et al.
The problem of deorbiting debris is studied in this paper. As a feasible measure, a disposable satellite would be launched, attach to debris, and deorbit the space debris using a technology named electrodynamic tether (EDT). In order to deorbit multiple debris as many as possible, a suboptimal but feasible and efficient trajectory set has been designed to allow a deorbiter satellite tour the LEO small bodies per one mission. Finally a simulation given by this paper showed that a 600 kg satellite is capable of deorbiting 6 debris objects in about 230 days.
The study on the measurement of the laser divergence angle based on the Gaussian model
Wei Tan, Xiao-bing Wang, Bao-hui Zhu, et al.
The laser divergence angle is an important parameter of laser beam quality. In order to meet the actual needs of engineering, a method for measuring the laser divergence angle was derived. The laser divergence angle was obtained by measuring the total laser energy and the laser energy behind the aperture. A measuring device was designed for validation. The experimental results showed that the result of the measurement was accurate with an error being smaller than 0.001 mrad . The entire measurement method and the system are simple, easy to operate and can quickly and accurately measure the laser divergence angle. They completely satisfy actual needs.
Study on phase-locked coherence of evanescent wave coupling in solid-state laser
Yong Chen, Xu Liu, Mengzhen Zhu, et al.
The mechanism and characteristics of evanescent-wave coupling in solid-state laser is analyzed theoretically and experimentally. The results shown that self-organized phase locking between laser modes can be realized by evanescentwave coupling in solid-state laser. Based on “mutual injection and evanescent wave” characteristics of corner-cube prism, the paper reveals that far-field output of corner-cube laser is the inner reason and mechanism of coherent combining distribution by theory of evanescent wave and its coherence is better than plane parallel resonator. And “mutually coupled phase locking of six lasers based cube-corner resonator” scheme is proposed on this basis.
Laser ranging system and measurement analysis for space debris with high repetition rate
Zhibo Wu, Haifeng Zhang, Wendong Meng, et al.
Laser measurement technology is inherently high accurate and will play an important role in precise orbit determination, accurate catalog, surveillance to space debris. Shanghai Astronomical Observatory (SHAO) has been developing the technology of laser measurement to space debris for several years. Based on the first successful laser ranging measurement to space debris in country, by applying one new set of high power 532nm wavelength laser system with 200Hz repetition rate, and adopting low dark noise APD detector with high quantum efficiency and high transmissivity of narrow bandwidth spectral filter, SHAO have achieved hundreds of passes of laser data from space debris in 2014, and the measured objects with distance between 500km and 2200km, Radar Cross Section (RCS) of >10m2 to <0.5m2 at the precision of <1m RMS for small RCS targets ,and the success rate of measured passes of up to 80%. The results show that laser ranging technology in China can routinely measure space debris and provide enough measurement data with high accuracy to space debris applications and researches such as surveillance activities in the future.
Novel Navigation Technology
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A method for measurement of static lever arm
Xianglu Ma, Shiqiao Qin, Xingshu Wang, et al.
Lever arm effect has to be considered in transfer alignment technology. Between static lever arm and dynamic lever arm, the former has larger amplitude, and it is the major error source in transfer alignment. How to measure and solve it become an important problem. This paper takes vehicle as a rigid body. Assume that static lever arm does not change in a short time, based on two inertial measurement units(IMU), data are measured and constituted several matrixes properly. After that, by using least square method, static lever arm is solved finally. Simulation experiments are implemented, results show that static lever arm can be solved effectively. Further study shows that, the precision of the method can be improved by preprocessing low pass filter.
Measurement of ship deformation based on ARX model
Xianglu Ma, Shiqiao Qin, Xingshu Wang, et al.
Ship deformation is the main error source of partial reference. Such deformation can be estimated by laser gyro units and Kalman filter technology. For Kalman filter, deformation was divide into two parts, dynamic deformation, and static deformation. Traditionally, dynamic deformation is treated as AR2 model .In this paper, dynamic deformation is taken as a kind of ARX model. Based on actual data measured by Yuanwang-3 Space Survey Ship, simulation experiments are studied. Results show that the novel model can improve the measurement precision.
Analysis and compensation for code Doppler effect of BDS II signal under high dynamics
Xiaofeng Ouyang, Fangling Zeng
In high dynamic circumstances, the acquisition of BDS (BeiDou Navigation Satellite System) signal would be affected by the pseudo-code Doppler. The pseudo-code frequency shift is more prominent and complex when BOC modulation has been adopted by BDS-II, but is not yet involved in current compensation algorithm. In addition, the most frequently used code Doppler compensation algorithm is modifying the sampling rate or local bit rate, which not only increases the complexity of the acquisition and tracking, but also is barely realizable for the hardware receiver to modify the local frequency. Therefore, this paper proposes a code Doppler compensation method based on double estimator receiver, which simultaneously controls NCO delay of code tracking loop and subcarrier tracking loop to compensate for pseudo-code frequency shift. The simulation and test are implemented with BDS-II BOC signal. The test results demonstrate that the proposed algorithm can effectively compensate for pseudo-code Doppler of BOC signal and has detection probability 3dB higher than the uncompensated situation when the false alarm rate is under 0.01 and the coherent integration time is 1ms.
The analysis on optical property for stereo vision measurement system
Zong-ming Liu, Dong Ye, Yu Zhang, et al.
In the relative measurement for the space non-cooperative target, the analysis to the optical property of the target is one of premises of the sensor design. The article is targeted on GEO satellites. From the perspective of photometry and based on the blackbody radiation law, we analyze the visible light energy of the sun outside the atmosphere, and consider the impact of satellite thermal control multilayer, model the luminosity feature related to the solar incident angle and the sensor observing angle. Finally we get the equivalent visual magnitude of the target satellite at the pupil of the camera. Our research could effectively direct the design and development of the visible relative measurement sensor.
Autonomous navigation algorithms based on improved CKF filters
Rong Zhu, Xiaogang Pan, Jiongqi Wang, et al.
Considering the great effects the measurement system errors of sensors have on satellite autonomous navigation, we study the filter algorithm for the navigation system with constant system error in this paper to improve the navigation precision. this paper improves conventional CKF algorithm and proposes an adaptive CKF filters based on model compensation, the state and bias estimation is performed separately using the CKF filters, and then the state variables are updated using the estimated bias. Finally, we verify the feasibility of the improved algorithm by simulation experiment, the simulation results show that the algorithm can improve the navigation accuracy.
Image navigation and performance evaluation through star observation with real sky for geostationary satellite wide FOV instrument
Xiaozheng Song, Yayun Wu, Jie Yu
Highly accurate image navigation has become a challenge due to the image distortion and thermal drift perturbations for geostationary satellite wide field-of-view(FOV) instrument with gimbaled mirror scan system. A novel instrument model of image navigation with few parameters is studied under lack of feature points. Its performance is evaluated through instrument star observation outdoors. The experimental results present that the image navigation approach yield high-precision compensation in full field of view. The accuracy is better than 60μrad, which demonstrates the enhanced image navigation capability to be obtained on further satellite missions.
Research on how the spacecraft-carried SINS/CNS avoids powerful light source based on three-dimension vector boundary
Baolin Ma, Jie Wu, Hongbo Zhang
This research has attempted to define the angle for avoiding powerful light by modeling based on three-dimension vector boundary, and provided the specific calculation method, so as to resolve the problem of avoiding powerful light. The simulation results show that the proposed computation of avoiding angle could judge in real time whether satisfy avoiding conditions, and the avoiding strategy could be chosen. So, the method and the strategy are of practical valve to industries.
Design of 300A constant current electronic load
Energy efficient and stable power supply is the core of most electronic products. DC electronic load is essential equipment to calibrate the DC regulated power supply. with the development of power industry towards to diversification and complication, the electronic load equipment for testing power supply is put forward higher requirements. Quality of electronic load equipment is mainly reflected in three aspects, measurement accuracy, completeness of measuring project and richness of load characteristic. In the paper, the high power and constant current DC electronic load is designed. Two pieces of D/A converter are used to constitute the 20 D/A conversion unit, to realize the minimum resolution of 0.045 mV. Four magnetic rings of high permeability and magnetic properties consistency, and the corresponding processing unit circuit compose the current sampling unit, which solve a key problem and difficulty of high precision and large current test. The three groups of 600 W power modules in parallel to realize the function of 1800 W power constant current. The electronic load has the 0 ~ 300A constant current characteristic, uncertainty of measurement is 1×10-4, and the maximum load voltage is 5V. After testing, every specifications have reached the design requirements. The load is mainly used for the metrology of DC regulated power supply.
Indoor visual positioning system using LED and mobile phone
An indoor visual positioning system is proposed, which using four or more LED ceiling lamps and a mobile phone. A 4*4 photodiode array is attached to the mobile phone to receive the three-dimensional coordinates of the LED lamps via visible light communication, and the front camera of the mobile phone is used to receive the high resolution image of the LED lamps. The mobile phone’s three-dimensional coordinates can be determined by matching the spot information and three-dimensional coordinates of the LED lamps with the image information provided by the mobile phone. An improved collinear equation model is proposed to build the mapping relationship between the three-dimensional coordinates of the LED lamps and the image information acquired by the front camera. A semi-physical simulation has been conducted and analyzed. The positioning scheme is proved to be valid and the positioning accuracy is up to decimeter level.
Design and development of grazing incidence x-ray mirrors
Fuchang Zuo, Zhiwu Mei, Tao Ma, et al.
X-ray pulsar navigation has attracted extensive attentions from academy and engineering domains. The navigation accuracy is can be enhanced through design of X-ray mirrors to focus X-rays to a small detector. The Wolter-I optics, originally proposed based on a paraboloid mirror and a hyperboloid mirror for X-ray imaging, has long been widely developed and employed in X-ray observatory. Some differences, however, remain in the requirements on optics between astronomical X-ray observation and pulsar navigation. The simplified Wolter-I optics, providing single reflection by a paraboloid mirror, is more suitable for pulsar navigation. In this paper, therefore, the grazing incidence X-ray mirror was designed further based on our previous work, with focus on the reflectivity, effective area, angular resolution and baffles. To evaluate the performance of the manufactured mirror, the surface roughness and reflectivity were tested. The test results show that the grazing incidence mirror meets the design specifications. On the basis of this, the reflectivity of the mirror in the working bandwidth was extrapolated to evaluate the focusing ability of the mirror when it works together with the detector. The purpose of our current work to design and develop a prototype mirror was realized. It can lay a foundation and provide guidance for the development of multilayer nested X-ray mirror with larger effective area.
The effective area calibration precision analysis of grazing incidence soft x-ray optical system
Yongqiang Shi, Zhiwu Mei, Zhengxin Lv, et al.
The grazing incidence soft X-ray optical system is the core equipment of future space science missions. The optical system expands the collecting area of x-ray photos and improves the SNR. The effective area calibration is the key indicator for testing and verifying the performance of the grazing incidence optical system. One of the traditional calibration methods uses the wide x-ray beam as the calibration x-ray source. This calibration method requires large ground equipment, high environmental conditions while the x-ray beam is not so parallel that the calibration accuracy is limited. Another effective area calibration method uses the narrow x-ray beam scan the optical system. In this paper, the above two effective area calibration methods of the grazing incidence optical system are modeled mathematically. The factors such as the parallelism of the beam, the uniformity of the beam and the characteristics of optical system are absorbed into the unified mathematical model for describing the effective area. The key factors which affect the effective area calibration accuracy are extracted, and their influences on the calibration result are analyzed. Eventually the two calibration methods accuracy is evaluated and the ways for improving the calibration accuracy are given. The effective area calibration is able to test and verify the collecting ability of x-ray photons of the grazing incidence optical system, which is the basis for the development of soft x-ray optics.
A design of driving circuit for star sensor imaging camera
Da-wei Li, Xiao-xu Yang, Jun-feng Han, et al.
The star sensor is a high-precision attitude sensitive measuring instruments, which determine spacecraft attitude by detecting different positions on the celestial sphere. Imaging camera is an important portion of star sensor. The purpose of this study is to design a driving circuit based on Kodak CCD sensor. The design of driving circuit based on Kodak KAI-04022 is discussed, and the timing of this CCD sensor is analyzed. By the driving circuit testing laboratory and imaging experiments, it is found that the driving circuits can meet the requirements of Kodak CCD sensor.
Autonomous celestial navigation based on Earth ultraviolet radiance and fast gradient statistic feature extraction
Shan Lu, Hanmo Zhang
To meet the requirement of autonomous orbit determination, this paper proposes a fast curve fitting method based on earth ultraviolet features to obtain accurate earth vector direction, in order to achieve the high precision autonomous navigation. Firstly, combining the stable characters of earth ultraviolet radiance and the use of transmission model software of atmospheric radiation, the paper simulates earth ultraviolet radiation model on different time and chooses the proper observation band. Then the fast improved edge extracting method combined Sobel operator and local binary pattern (LBP) is utilized, which can both eliminate noises efficiently and extract earth ultraviolet limb features accurately. And earth’s centroid locations on simulated images are estimated via the least square fitting method using part of the limb edges. Taken advantage of the estimated earth vector direction and earth distance, Extended Kalman Filter (EKF) is applied to realize the autonomous navigation finally. Experiment results indicate the proposed method can achieve a sub-pixel earth centroid location estimation and extremely enhance autonomous celestial navigation precision.
Optimization design about gimbal structure of high-precision autonomous celestial navigation tracking mirror system
Wei Huang, Xiao-xu Yang, Jun-feng Han, et al.
High precision tracking platform of celestial navigation with control mirror servo structure form, to solve the disadvantages of big volume and rotational inertia, slow response speed, and so on. It improved the stability and tracking accuracy of platform. Due to optical sensor and mirror are installed on the middle-gimbal, stiffness and resonant frequency requirement for high. Based on the application of finite element modality analysis theory, doing Research on dynamic characteristics of the middle-gimbal, and ANSYS was used for the finite element dynamic emulator analysis. According to the result of the computer to find out the weak links of the structure, and Put forward improvement suggestions and reanalysis. The lowest resonant frequency of optimization middle-gimbal avoid the bandwidth of the platform servo mechanism, and much higher than the disturbance frequency of carrier aircraft, and reduces mechanical resonance of the framework. Reaching provides a theoretical basis for the whole machine structure optimization design of high-precision of autonomous Celestial navigation tracking mirror system.
Analysis of response delay of the attitude in a single-axis rotation INS/GPS system
Jing Zhu, Xingshu Wang, Jun Wang, et al.
Deflections of the vertical (DOV) are normally ignored in the gravity compensation procedure, which become one of the primary error sources in inertial navigation. In a single-axis rotation INS/GPS system, bias of the gyro and the accelerometer can be ignored, the attitude error is mainly affected by DOV. In this paper, the ideal system assumption is abandoned and the influence of DOV on the attitude is comprehensively discussed, which can be divided into two parts i.e. the direct influence and the indirect influence. The attitude error tracks the DOV along the trajectory belongs to the former. A relatively fixed delay between the attitude error and the DOV belongs to the latter. The delay is essentially induced by the weak observability of the system to the violent DOV. Factors which affect the delay are carefully analyzed. The simulation results show that the delay is mainly affected by accuracies of the inertial sensors and the GPS. It decreases with the GPS accuracy increasing, but increases with the inertial sensor accuracy increasing. The process noise covariance matrix Q plays an important role. With analysis of the characteristics of the delay, influence of the DOV on attitude is studied further, which is necessary for the attitude correction in future.
Simulation of x-ray transmitted in the square polycapillary x-ray lens
Shiqi Peng, Zhiguo Liu, Tianxi Sun, et al.
To study the transmission property of the square polycapillary x-ray lens and verify its feasibility using in the x-ray pulsar navigation a geometrical description of it and the basic theory of the transmission of x-rays are presented. A method of numerical calculation is developed based on ray-tracing theory. The method simulates the intensity distribution and calculates the transmission efficiency of x-rays propagating through a square polycapillary lens. The transmission rule of the x-ray propagation in the x-ray lens can be got, after tracing a large number of x-ray beams. A program based on ray-tracing method was designed to simulate the transmission efficiency of an x-ray lens and the light spot gained from it. The transmission property of the square polycapillary x-ray lens is studied based on this program. And the study shows that the transmission property of the square polycapillary x-ray lens is good, and it has the potential of being used in the area of x-ray pulsar navigation.
Pedestrian navigation algorithm based on MIMU with building heading/magnetometer
Xiang-bin Meng, Xian-fei Pan, Chang-hao Chen, et al.
In order to improve the accuracy of the low-cost MIMU Inertial navigation system in the application of pedestrian navigation.And to reduce the effect of the heading error because of the low accuracy of the component of MIMU. A novel algorithm was put forward, which fusing the building heading constraint information and the magnetic heading information to achieve more advantages. We analysed the application condition and the modified effect of building heading and magnetic heading. Then experiments were conducted in indoor environment. The results show that the algorithm proposed has a better effect to restrict the heading drift problem and to achieve a higher navigation precision.
Profile bias’ influence in x-ray pulsar based navigation
Dapeng Zhang, Wei Zheng, Yidi Wang, et al.
X-ray pulsar-based navigation is a novel autonomous navigation method. The pulsar is a kind of neutron star rotating with high speed. Its angle position is stationary in space and its rotation period is extremely stable. In space, the signal with extremely stable period could be detected. Its long-term stability is higher than the atomic clock in state-of-the-art. Therefore, the signal of the pulsars in X-ray waveband could be used for the autonomous navigation of the spacecrafts. The signal’s profile is a necessary parameter to estimate the navigation information. In this paper, the impact on the navigation precision caused by the flux bias of the signal’s profile is analyzed. The impact is not severely proved in theory and simulation.
Research on the airborne SINS/CNS integrated navigation system assisted by BD navigation system
Mei-lin Xie, Xiao-xu Yang, Jun-feng Han, et al.
When the star navigation system working during the day, the strong sky background radiation lead to a result that the detect target light is too weak, in the field of view, because of the limitation on the number of the navigation star, usually choose the single star navigation work mode. In order to improve the reliability of the airborne SINS/CNS integrated navigation system, meet the demand of the long-endurance and high precision navigation, use the tight combination way, single star patrol algorithm to get the position and attitude. There exists filtering divergence problem because of the model error and the system measurement noise is uncertain, put forward a new fuzzy adaptive kalman filtering algorithm. Adjust the size of measurement noise to prevent the filter divergence; the positioning accuracy of integrated navigation system can be improved through BeiDou satellite. Without the information of BeiDou satellite, based on the level of the virtual reference, the navigation precision of integrated navigation system can be ensured over a period of time.
Sensitivity requirements of assisted BDS and GPS in specification 3GPP TS 36.171
Xiaoxi Jin, Xin Chen, Rendong Ying, et al.
With the needs of growing location-based service, a more high-performance satellite positioning technology - assisted global navigation satellite system (A-GNSS assisted-GNSS) becomes a new hotspot in area of navigation and positioning. Now, 3GPP has already provided supports for GPS, Galileo, GLONASS and QZSS, SBAS, so standardization work of introduction BDS into 3GPP organization is very imperative. In this paper, we first analysis the performance of GPS L1 C/A with assistant information, then by taking into account the difference between BDS and GPS, including the unique nature of GEO/NGEO satellites’ navigation message data length and format, we design the sensitivity requirements of BDS B1 following A-GPS. The results between A-GPS and A-BDS of typical sensitivity test cases are shown in this paper, which show that the suggested sensitivity requirements satisfy the minimum performance requirements under technical specification of 3GPP TS 36.171.
A low complexity, low spur digital IF conversion circuit for high-fidelity GNSS signal playback
Fei Su, Rendong Ying
A low complexity high efficiency and low spur digital intermediate frequency (IF) conversion circuit is discussed in the paper. This circuit is key element in high-fidelity GNSS signal playback instrument. We analyze the spur performance of a finite state machine (FSM) based numerically controlled oscillators (NCO), by optimization of the control algorithm, a FSM based NCO with 3 quantization stage can achieves 65dB SFDR in the range of the seventh harmonic. Compare with traditional lookup table based NCO design with the same Spurious Free Dynamic Range (SFDR) performance, the logic resource require to implemented the NCO is reduced to 1/3. The proposed design method can be extended to the IF conversion system with good SFDR in the range of higher harmonic components by increasing the quantization stage.
X-ray pulsar navigation precision analysis considering orbit propagation error effects
Heng Shi, Kai Xiong, Chunling Wei, et al.
Orbit propagation error effects are considered in precision analysis of X-ray pulsar navigation (XNAV) systems which integrating orbit dynamics model and pulse time of arrival observation. Precision analysis model is established, and the concept of optimal pulse observation accumulation time is proposed based on coupling analysis of orbit propagation error, pulsar observation process and pulse time of arrival observation precision. The estimation algorithm of optimal observation accumulation time is presented as an important tool for XNAV observation planning and scheme design.
Numerical simulation of melt ejection during the laser drilling process on aluminum alloy by millisecond pulsed laser
Zhang Wei, Guangyong Jin, Yibin Wang
In this paper, established a physical model to simulate the melt ejection induced by millisecond pulsed laser on aluminum alloy and use the finite element method to simulate the whole process. A semi-infinite axisymmetric model was established according to the experiment and the analytical solution of temperature in a solid phase was derived based on the thermal conduction equation. Mean while, by assuming that material was removed from the hole once it was melted, the function describing the hole's shape was obtained with the energy balance theory. This simulation is based on the interaction between single pulsed laser with different pulse-width and different peak energy and aluminum alloy material, the result of numerical simulation is that the hole's depth increases with the increase of laser energy and the hole's depth increases with the increase of laser pulse width, the keyhole depth is linearly increased with the increase of laser energy, respectively; the growth of the keyhole radius is in the trend to be gentle. By comparing the theoretical simulation data and the actual test data, we discover that: we discover that: the relative error between the theoretical values and the actual values is about 8.8%, the theoretical simulation curve is well consistent with the actual experimental curve. This research may provide the theoretical references to the understanding of the interaction between millisecond pulsed laser and many kinds of materials, as well as be beneficial to the application of the laser materials processing and military field.
The X-ray optics for X-ray pulsar navigation
Dongdong Jin, Wenbin Li, Jian Lian, et al.
The effective X-ray optics is a key premise for X-ray pulsar detection and navigation. However, it is very difficult to focus the X-ray photons through refraction for the reason that the X-ray photon is very easy to be absorbed by the materials. The most effective ways for the X-ray focusing is reflection. In this paper, we will give a brief introduction of the theory of the grazing incidence and the corresponding optical systems. By comparing the design parameters of main X-ray astronomical telescope in NASA and ESA, we will give the development trend of the X-ray optics for X-ray pulsar navigation and introduce several new technology for the manufacture of the micro-pore optics (MPO).
Rotation sensing with a circular atomic waveguide
Lian-jie Zhao, Xiao-jun Yan, Guo-wan Zhang, et al.
The hollow metallic optical fibers not only retain the advantage of flexibility but possess a greater intensity gradient for atomic waveguide. Therefore, based on the vector model of Maxwell’s equations, we exactly calculated the intensity distribution of the TE01 mode in a typical metallic fiber, and analyzed the optical potential for 85Rb atom. Most of all, based on a circular atomic waveguide, we creatively proposed a novel measurement scheme for rotation sensing, explained the specific measurement principle, and built a mathematical model for this novel scheme. By measuring the number of atoms in the final states, we could get the rotation rate for this typical rotation system. This novel rotation sensor not only possessed a higher measurement precision, but realized the continuity measurement. It will be widely used in navigation, geophysics and general relativity.
Single pixel star sensor
Ran Yang, Mingfei Li, Juan Huo, et al.
In this paper, a single pixel star sensor has been introduced, which uses the intensity correlation between the modulation matrix and the voltage values of the optical signals. Though controlling single or multiple the reflective mirror of the spatial light modulator as a pixel, it is given in a rough scan or an accurate imaging of the stars. As a result, this star sensor can realize a fast and high precision spacecraft attitude determination.
New micro pore optics for x-ray pulsar navigation
Ge Jin, Qindong Zhang, Zhao Xu, et al.
Solutions of focusing pulsars X-ray is a key factor in improving the accuracy of pulsar navigation. Based on the focusing principle of lobster eye grazing incidence, new micro pore optics (MPO) for pulsar navigation which is glass-substrated X-ray MPO is researched and developed. The effective areas on MPO when single grazing incidence or double grazing incidence happens are analyzed in detail and the first generation of MPO is produced. By illumination of parallel X-ray beam with 1.49keV and 8.05keV on the MPO, it is found that the crossing focusing image can be clearly visible, and the arm of cross image of 1.49keV and 8.05keV are is respectively 30mm and 17mm in length. Moreover, the center intensity was significantly higher than the cross arm which is consistent with theoretical calculation. Besides, the angular resolution of first generation of MPO with 8.05keV parallel X-ray beam illuminated is 4.19’.
The theory and experiment about x-ray focusing performance of micro pore optics
Hanqi Mao, Longhui Li, Jianning Sun, et al.
Micro pore optics (MPO) is an effective approach of miniaturization for pulsars navigation X-ray focusing and imaging. The focusing performance is one of the core indicators of evaluating the X-ray detection system. By using the X-ray detection optical system, imaging and X-ray focusing performance of MPO are investigated. The experimental results show that the MPO can make the X-ray to be converged into a clear cross image at the focal length. At the same time, compared with no coating, the coating slumped MPO focusing performance is improved significantly, the center of the power density is gaining up to 4–5 times. The optical system can achieve hundreds of micron resolution in the hundreds of mm view, and space angular resolution can reach arcmin level.
A differential augmentation method based on aerostat reference stations
Ground based regional augmentation systems is unable to cover regions such as the oceans, mountains and deserts. And its signal is vulnerable of building block. Besides, its positioning precision for high airspace object is limited. To settle such problems, a Differential augmentation method based on troposphere error corrections using aerostat reference stations is proposed. This method utilizes altitudes of mobile station and aerostat station to estimate troposphere delay errors, resulting in troposphere delay difference value between mobile stations and aerostat reference stations. With the aid of satellite navigation information of mobile stations and aerostat station and both troposphere delay difference values, mobile stations’ positioning precision is enhanced by eliminating measurement errors (Satellite clock error, Ephemeris error, Ionospheric delay error, Tropospheric delay error) after differential. It is showed by simulation test that aerostat reference station Differential augmentation method based on tropospheric error corrections improves 3D positioning precision of mobile station to within 2m.
Testing and Driving of Laser Fusion Energy Technology
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Study on the laser irradiation characteristics of NEPE propellant in different oxygen concentrations
Hengsheng Xiang, Xiong Chen, Changsheng Zhou
The ignition and combustion characteristics of nitrate ester plasticized polyether (NEPE) propellant in different oxygen concentrations ambient gases were studied by the application of CO2 laser, infrared thermometer and high speed camera. The flame intensity data of the propellant was collected by the photodiode; propellant flame temperature was measured by infrared thermometer. The experimental results show that the time which NEPE propellant spend to be stable combustion will get shorter with the increase of oxygen concentration; the flame peak temperature measured by infrared thermometer increases with the increase of oxygen concentration when the oxygen concentration is less than 30% by volume, then decreases with the increase of oxygen concentration.
1053-nm all-fiber multi-pulse phase modulator for chirped pulse amplification
An all-fiber multi-pass phase modulator for chirped pulse amplification centered at 1053nm is demonstrated. An optical pulse with a 3-dB bandwidth of 2.23nm centered at 1053 nm is obtained based on the system. And spectrum with negative dispersion is obtain by an all-fiber architecture which can be used for ultrashort laser source in ps.
Power delivery experiment of a selected cut-off wavelength optical fiber
The power output of 2km and 8km 80μm selected cut-off wavelength single mode optical fiber was measured by 2.4W ASE fiber source at 1550nm waveband. The results show that obvious nonlinearity in 2km fiber does not occur by way of output power and spectrum. Slight nonlinearity is seen in 8km fiber. The power variation is small during the test of power stability with 1.28W input in 8km fiber.
Research of loss detection of optic path for laser ignition application
Jia Liu, Haina Liu, Jinjun Jin, et al.
We present some different kinds of the loss detection technologies of optic path for laser ignition application according to the recommend of reliability and security of the laser ignition system, such as single wavelength and dual wavelength. The factors of loss detection technology are discussed. The difficulty and uptrend of the laser ignition system are pointed out in this paper. The correlation research will be focused on the reliability of optic parts, applicability of environment and special fiber in the future.
Fabrication and researching of weathering resistant double cladding power delivery fiber
Liang Rong, Junjiang Ren, Rundong Li, et al.
A novel well weathering resistant power delivery fiber which is of double cladding and high optical energy transmitting ability is developed via fluoroplastic out sheath extruding process. The fiber has been comprehensively evaluated including optical performance, mechanical performance, environmental suitability and laser transmitting property. It is shown that the fiber has not only low attenuation, high numerical aperture and better mechanical bending performance, but also outstanding weathering resistance and high power laser transmitting performance, which implies the qualification of the fiber for various kinds of applying situations, such as laser ignition, laser induced expanding sound underwater, ship-based and airborne laser weapon.
A unidirectional two-pulse amplifying architecture for laser fusion facilities
Min Li, Xiaomin Zhang, Wenyi Wang, et al.
A unidirectional two-pulse amplifying architecture (UTPA) was proposed to amplify the laser pulses in inertial confinement fusion and fusion energy facilities. Compared with laser output performance in the conventional single pulse amplifier (SPA), the preliminary results show that although the performance in SPA and UTPA with the gain media of Yb:YAG operating at 200K are almost equal with output energies of 8.12 kJ and 8.26 kJ, and extraction efficiencies of 79.5% and 81.4%, respectively; however, at the maximum output in SPA, ΣB increases up to 3.499 rad close to the limitation of 3.5 rad, while in UTPA ΣB is relative small with the value of 1.769 rad, which reduces the nonlinear effects for high power pulses and is beneficial to system reliability and stability. In addition, for achieving a pulse with squared temporal shape, the demands for the pre-shaping ability of the laser system were significantly reduced in UTPA by around 6 times. With ΣB margins in UPTA, it is possible to scale the output performance with high extraction efficiency by increasing the gain coefficient or the slaps.
The simulation for the temporal characteristic of the microchannel plate
Houzhi Cai, Jinghua Long, Jinyuan Liu, et al.
Framing cameras based on the gated microchannel plate (MCP) are versatile diagnostic tools for fast Z-pinch and inertial confinement fusion experiments. In order to understand the temporal characteristic of the MCP used in such camera, the MCP is simulated using the Monte Carlo method. By simulating the electron cascade in the MCP, the relationship between the MCP temporal resolution and the ratio of its thickness to the channel diameter (L/D ratio) is obtained. The variation of the temporal resolution with the voltage applied on the MCP is also provided. The transit time and the transit time spread (TTS) simulations of the MCP are presented. The simulated results show that the transit time and TTS of the MCP are increased with L/D ratio increasing while the channel diameter of the MCP is 10 um.
Progress of the array laser detonation technology
Peng Ren, Rui Zhang, Ai-feng He, et al.
This paper stated the main characteristics of the array laser technology, introduced high application and development at home and abroad, especially having a comparison of solid array laser technology with semiconductor array laser technology on fast initiation and fire energy, etc. by researchment of the array laser technology, this paper forsaw the prospect of the array laser. at last, this paper summaries plenty of advantages of the laser array technology on miniaturization, intellectualization, integration.
A high-voltage supply used on miniaturized RLG
Zhifei Miao, Mingming Fan, Yuepeng Wang, et al.
A high voltage power supply used in laser gyro is proposed in this paper. The power supply which uses a single DC 15v input and fly-back topology is adopted in the main circuit. The output of the power supply achieve high to 3.3kv voltage in order to light the RLG. The PFM control method is adopted to realize the rapid switching between the high voltage state and the maintain state. The resonant chip L6565 is used to achieve the zero voltage switching(ZVS), so the consumption is reduced and the power efficiency is improved more than 80%. A special circuit is presented in the control portion to ensure symmetry of the two RLG's arms current. The measured current accuracy is higher than 5‰ and the current symmetry of the two RLG's arms up to 99.2%.
Research on absorption test methods of Yb-doped double cladding fiber
Pupu Wang, Rundong Li, Liang Rong, et al.
Absorption coefficient is a very useful feature for active fiber. In fiber laser system, the length of active fiber is chosen according to absorption coefficient. And the length of fiber can directly influence the feature of fiber laser. Therefore, how to obtain an accurate absorption coefficient is very important. Because fiber exists re-emission in typical absorption band pumped by power. It is difficult to accurately measure absorption coefficient. The absorption coefficients of Yb-doped double cladding fiber at 975 nm measured by several methods were compared. In conclusion, for the fibers with same length pumped by white light, the absorption coefficient is the highest when cutback only once. Meanwhile, when fibers with different length were measured by the same method, the absorption coefficient is inversely proportional to optical fiber length.
Perspective of laser-induced plasma ignition of hydrocarbon fuel in Scramjet engine
Leichao Yang, Xiaohui Li, Jianhan Liang, et al.
Laser-induced plasma ignition of an ethylene fuelled cavity was successfully conducted in a model scramjet engine combustor. The ethylene was injected 10mm upstream of cavity flameholder from 3 orifices 60 degree inclined relative to freestream direction. The 1064nm laser beam, from a Q-switched Nd:YAG laser source running at 3Hz and 200mJ per pulse, was focused into cavity for ignition. High speed photography was used to capture the transient ignition process. The laser-induced gas breakdown, flame kernel generation and propagation were all recorded and ensuing stable supersonic combustion was established in cavity. The flame kernel is found rotating anti-clockwise and gradually moves upwards as the entrainment of circulation flow in cavity. The flame is then stretched from leading edge to trailing edge to fully fill the entire cavity. Eventually, a stable combustion is achieved roughly 900μs after the laser pulse. The results show promising potentials for practical application. The perspective of laser-induced plasma ignition of hydrocarbon fuel in scramjet engine is outlined.
The simulative calculation and optimum design for FOA, the purge gas sweeping system
Liquan Wang, Yukun Jing, Bing Feng, et al.
This paper first studies the structure effect law in order to design a reasonable option in theory for the Final Optics Assembly(FOA)’ harmonic converter module, involved in the design of the fluid theory, including the basic equations of fluid motion, the form of fluid motion and fluid movement in the small hole. Optimizing the structure need to be applied to the simulation software, which requires the Fluent simulation principle. Then, combined with theoretical knowledge to design the overall structure of the multiplier module, It will apply the simulation software to optimize structural parameters of the board and use control system to realize it for verifying the law obtained by simulation under various conditions whether consistent with the law in actual work of the sweeping system.
The detection capability of space-based combined system for space debris
Yalin Zhang, Chao Wang, Qiang Fu, et al.
It is urgent to tracking and making a catalog for space debris, since they are such serious threats to spacecraft. Space-based detection possess a great of development potential for its low energy consumption, high precision and miniaturization and other features. This paper discussed the capability of space-based combined system that is laser ranging and imaging integrated communication system. With the diameter of 15cm of space debris, the limit distance of communication, ranging and imaging system are discussed. The result shows that the limit distance of communication and energy imaging is longer, and the main factor to limit the distance is ranging and diffraction limit of imaging system.
UAV Payload Technology
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Ground target detection based on discrete cosine transform and Rényi entropy for imaging ladar
Yuannan Xu, Weili Chen, Junwei Li, et al.
The discrete cosine transform (DCT) due to its excellent properties that the images can be represented in spatial/spatial-frequency domains, has been applied in sequence data analysis and image fusion. For intensity and range images of ladar, through the DCT using one dimension window, the statistical property of Rényi entropy for images is studied. We also analyzed the change of Rényi entropy’s statistical property in the ladar intensity and range images when the man-made objects appear. From this foundation, a novel method for generating saliency map based on DCT and Rényi entropy is proposed. After that, ground target detection is completed when the saliency map is segmented using a simple and convenient threshold method. For the ladar intensity and range images, experimental results show the proposed method can effectively detect the military vehicles from complex earth background with low false alarm.
Modeling and analyzing characteristics of self-infrared radiation on airplane-skin
The characteristic of the self-infrared radiation of airplane-skin is very important for the stealth performance of airplane. Based on the theory of the airplane-skin temperature field, the distribution of the atmospheric temperature field and the principle of the black-body radiation function the self-infrared radiation model was established. In specified flight conditions, the influence of the atmospheric temperature, the speed of flight, the emissivity and the sight angle detection on the self-infrared radiation of the airplane skin were analyzed. Through the simulation of infrared radiation, some results under different flight states are obtained. The simulation results show that skin infrared radiation energy mainly concentrate on the far infrared wavebands, and various factors have different effects on the infrared radiation of skin. This conclusion can help reduce the infrared radiation and improve the stealth performance of airplane in the engineering design and the selection of flight conditions.
Navigation and geo-tracking system of UAV EO payload
Ying Chen, Kang Zhen, Yuanyuan Xue, et al.
A multi-function system based on inertial measurement unit (IMU) is introduced, which can fulfill navigation, attitude measurement of LOS in payload, platform stabilization and tracking control. The IMU is integrated with electro-optical sensors and a laser range finder on gimbals, which performs attitude calculation and navigation by constructing navigation coordinates in a mathematic platform, and the platform navigation information is obtained by transformation matrix between platform and gimbal coordinates. The platform comprising of gyros, electro-optical sensors and servo mechanism is capable of stabilizing line of sight and could be used to geo-tracking in the relevant field of view (FOV).The system can determine geography coordinates of the host platform and target only with navigation information and laser ranging data. The geo-tracking system always locked the target image at the center of FOV by calculating spatial geometry and adjusting LOS attitude. This tracking is different from TV tracking and geographical reference image tracking, which may be influenced by fog and obscurant. When the UAV is flying over urban or mountain areas for rescue missions, it can avoid the loss of targets due to strong maneuver or LOS obscuration, and reduce the operation load and improve rescue efficiency.
Improvement of sub-pixel global motion estimation in UAV image stabilization
Yingjuan Li, Ming Ji, Junfeng He, et al.
Global motion estimation within frames is very important in the UAV(unmanned aerial vehicle) image stabilization system. A fast algorithm based on phase correlation and image down-sampling in sub-pixel was proposed. First, down-sampling of the two frames to quantitatively reduce calculate data. Then, take the method based of phase correlation to realize the global motion estimation in integer-pixel. When it calculated out, chooses the overlapped area of the two frames and interpolated them with zero, then adopts the method based on phase correlation to achieve the global motion estimation in sub-pixel. At last, weighted calculate the result in integer-pixel and the result in sub-pixel, the global motion displacement in sub-pixel of the two images will be calculated out. Experimental results show that, using the proposed algorithm can not only achieve good robustness to the influence of noise, illumination and partially sheltered but also improve the accuracy of motion estimation and efficiency of computing significantly.
Feasibility study of a novel miniaturized spectral imaging system architecture in UAV surveillance
Shuyang Liu, Tao Zhou, Xiaodong Jia, et al.
The spectral imaging technology is able to analysis the spectral and spatial geometric character of the target at the same time. To break through the limitation brought by the size, weight and cost of the traditional spectral imaging instrument, a miniaturized novel spectral imaging based on CMOS processing has been introduced in the market. This technology has enabled the possibility of applying spectral imaging in the UAV platform. In this paper, the relevant technology and the related possible applications have been presented to implement a quick, flexible and more detailed remote sensing system.
Optical design for large depth of field
Yang Shen, Hu Wang, Pan Yue, et al.
Optical system with large depth of field and large field of view has been designed. To enforce optical system with focal length of 6 mm to imaging the object with object length of 200mmm-1200mm, accord to the equation of depth of field, in case of the CCD sensor with pixel of 5.5umx 5.5um square area, the entrance pupil diameter to ideal imaging will be 0.423mm. To enlarge the modulation transfer function (MTF) at spatial frequency of 90 lp/mm, the entrance pupil diameter is enlarged to 1mm.After design and optimization, with field of view of 80°, within object length of 200mm - 1200mm, the optical system can imaging well, the modulation transfer function (MTF) at spatial frequency of 90lp/mm is larger than 0.1, the distortion of full field of viewed is less than 3%.The optical system can be widely used in machine vision, surveillance cameras, etc.
Thermal/structural/optical integrated design for optical sensor mounted on unmanned aerial vehicle
Gaopeng Zhang, Hongtao Yang, Chao Mei, et al.
With the rapid development of science and technology and the promotion of many local wars in the world, altitude optical sensor mounted on unmanned aerial vehicle is more widely applied in the airborne remote sensing, measurement and detection. In order to obtain high quality image of the aero optical remote sensor, it is important to analysis its thermal-optical performance on the condition of high speed and high altitude. Especially for the key imaging assembly, such as optical window, the temperature variation and temperature gradient can result in defocus and aberrations in optical system, which will lead to the poor quality image. In order to improve the optical performance of a high speed aerial camera optical window, the thermal/structural/optical integrated design method is developed. Firstly, the flight environment of optical window is analyzed. Based on the theory of aerodynamics and heat transfer, the convection heat transfer coefficient is calculated. The temperature distributing of optical window is simulated by the finite element analysis software. The maximum difference in temperature of the inside and outside of optical window is obtained. Then the deformation of optical window under the boundary condition of the maximum difference in temperature is calculated. The optical window surface deformation is fitted in Zernike polynomial as the interface, the calculated Zernike fitting coefficients is brought in and analyzed by CodeV Optical Software. At last, the transfer function diagrams of the optical system on temperature field are comparatively analyzed. By comparing and analyzing the result, it can be obtained that the optical path difference caused by thermal deformation of the optical window is 138.2 nm, which is under PV ≤1 4λ . The above study can be used as an important reference for other optical window designs.
Analysis of Unmanned Aerial Vehicle (UAV) hyperspectral remote sensing monitoring key technology in coastal wetland
The coastal wetland, a transitional zone between terrestrial ecosystems and marine ecosystems, is the type of great value to ecosystem services. For the recent 3 decades, area of the coastal wetland is decreasing and the ecological function is gradually degraded with the rapid development of economy, which restricts the sustainable development of economy and society in the coastal areas of China in turn. It is a major demand of the national reality to carry out the monitoring of coastal wetlands, to master the distribution and dynamic change. UAV, namely unmanned aerial vehicle, is a new platform for remote sensing. Compared with the traditional satellite and manned aerial remote sensing, it has the advantage of flexible implementation, no cloud cover, strong initiative and low cost. Image-spectrum merging is one character of high spectral remote sensing. At the same time of imaging, the spectral curve of each pixel is obtained, which is suitable for quantitative remote sensing, fine classification and target detection. Aimed at the frontier and hotspot of remote sensing monitoring technology, and faced the demand of the coastal wetland monitoring, this paper used UAV and the new remote sensor of high spectral imaging instrument to carry out the analysis of the key technologies of monitoring coastal wetlands by UAV on the basis of the current situation in overseas and domestic and the analysis of developing trend. According to the characteristic of airborne hyperspectral data on UAV, that is "three high and one many", the key technology research that should develop are promoted as follows: 1) the atmosphere correction of the UAV hyperspectral in coastal wetlands under the circumstance of complex underlying surface and variable geometry, 2) the best observation scale and scale transformation method of the UAV platform while monitoring the coastal wetland features, 3) the classification and detection method of typical features with high precision from multi scale hyperspectral images based on time sequence. The research results of this paper will help to break the traditional concept of remote sensing monitoring coastal wetlands by satellite and manned aerial vehicle, lead the trend of this monitoring technology, and put forward a new technical proposal for grasping the distribution of the coastal wetland and the changing trend and carrying out the protection and management of the coastal wetland.
An improved dehazing algorithm of aerial high-definition image
Wentao Jiang, Ming Ji, Xiying Huang, et al.
For unmanned aerial vehicle(UAV) images, the sensor can not get high quality images due to fog and haze weather. To solve this problem, An improved dehazing algorithm of aerial high-definition image is proposed. Based on the model of dark channel prior, the new algorithm firstly extracts the edges from crude estimated transmission map and expands the extracted edges. Then according to the expended edges, the algorithm sets a threshold value to divide the crude estimated transmission map into different areas and makes different guided filter on the different areas compute the optimized transmission map. The experimental results demonstrate that the performance of the proposed algorithm is substantially the same as the one based on dark channel prior and guided filter. The average computation time of the new algorithm is around 40% of the one as well as the detection ability of UAV image is improved effectively in fog and haze weather.
The electronic image stabilization technology research based on improved optical-flow motion vector estimation
Chao Wang, Ming Ji, Ying Zhang, et al.
The electronic image stabilization technology based on improved optical-flow motion vector estimation technique can effectively improve the non normal shift, such as jitter, rotation and so on. Firstly, the ORB features are extracted from the image, a set of regions are built on these features; Secondly, the optical-flow vector is computed in the feature regions, in order to reduce the computational complexity, the multi resolution strategy of Pyramid is used to calculate the motion vector of the frame; Finally, qualitative and quantitative analysis of the effect of the algorithm is carried out. The results show that the proposed algorithm has better stability compared with image stabilization based on the traditional optical-flow motion vector estimation method.
Design and implementation of interactive strap-down inertial navigation simulation system for UAV
Chuan-qi Cheng, Xiang Cheng, Xiang-yang Hao, et al.
Strap-down inertial navigation system (SINS) is widely used in military field, to facilitate the study of SINS algorithms and various coupled navigation algorithms, a simulation system of SINS is designed. Based on modular design, with good portability and expansibility, the system consists of four independent modules: analysis module of motion state, trajectory simulator, IMU simulation module and SINS calculation module. With graphical interface, the system can control every motion state of the trajectory, which is convenient to generate various trajectories efficiently. Using rotation vector attitude algorithm to process simulation data, experiment results show that the attitude, velocity and position error is consistent with the theoretical value, which verifies the rationality of the simulation model and the availability of the simulation system.
Object-oriented recognition of high-resolution remote sensing image
With the development of remote sensing imaging technology and the improvement of multi–source image's resolution in satellite visible light, multi-spectral and hyper spectral , the high resolution remote sensing image has been widely used in various fields, for example military field, surveying and mapping, geophysical prospecting, environment and so forth. In remote sensing image, the segmentation of ground targets, feature extraction and the technology of automatic recognition are the hotspot and difficulty in the research of modern information technology. This paper also presents an object-oriented remote sensing image scene classification method. The method is consist of vehicles typical objects classification generation, nonparametric density estimation theory, mean shift segmentation theory, multi-scale corner detection algorithm, local shape matching algorithm based on template. Remote sensing vehicles image classification software system is designed and implemented to meet the requirements .
Research on aided navigation based on terrain elevation matching and simulation
Yanping He, Xinxue Liu, Yanping Cai, et al.
The matching function of terrain-aided navigation is not only related to the algorithm, also associated with the terrain characteristics of matching area. Aiming at terrain matching area selection and matching algorithm of the terrain height matching system, the method of terrain information entropy is put forward on the basis of statistical characteristics of the terrain roughness, signal-to-noise ratio, and then COR algorithm, MAD algorithm, MSD algorithm is adopted for real-time map and reference map matching, finally shows the simulation comparison of three kinds of matching algorithm. Result of simulation shows that among the index of matching accuracy and speed of three kinds of algorithm, COR algorithm possess fastest calculation speed and lowest precision, matching accuracy of MSD is slightly higher than MAD algorithm and calculation speed of MSD is placed in the middle, and the simulation results provide selection basis for terrain-aided inertial navigation.