2014 Vol. 43, No. 12
2014, 43(12): 3861-3865.
Pushbroom imaging technology based on long linear array MWIR and LWIR detectors is one of the major technical solutions to achieve high spatial resolution and high temperature resolution satellite earth observation. With the development of long linear array infrared detectors, great attention has been given to this technology and it has been applied in some areas. The characteristics of MWIR and LWIR imaging were introduced. The current status of satellite pushbroom imaging based on long linear array MWIR and LWIR detectors was presented. Emphasis was put on the analysis of MWIR and LWIR imaging performances, including modulation transfer function (MTF), ground sampled distance (GSD), and noise equivalent temperature difference (NETD), according to their wavelength, radiation intensity of object with a temperature of 300 K, and parameters of optics and detectors. For objects with ambient temperature, if integration time was long enough, the MWIR pushbroom imaging can achieve higher spatial resolution and temperature resolution than LWIR under the same MTF. Some suggestions for improving MWIR and LWIR imaging performances were given according to the analysis result.
2014, 43(12): 3866-3871.
The size, shape and search strategy of field of view are important factors which impact the acquisition probability of infrared imaging seeker. The theory that seeker's field of view impacting acquisition probability was analyzed, and on the basis, the concept of search field and acquisition field were defined. After that, several types of field of view working models were established and compared, which had different shapes and search strategies. The simulation and calculation cases indicate that the area of acquisition field is not more than search field, and different shapes and search strategies achieve different sizes acquisition fields, which should be optimally selected according to design requirements. The involved research methods and conclusions provide theoretical references to the field of view selection and search strategy design for infrared imaging seeker.
2014, 43(12): 3872-3876.
CaS:Eu2+, Sm3+ infrared up-conversion screens were prepared by the gravity deposition method, the optimum preparation parameters of screens were determined and the properties of the infrared up- conversion screens were researched. A coupled short wavelength infrared CCD camera was designed and manufactured. The imaging properties were tested and the results show that the obtained coupled CCD camera is able to detect 1 064 nm and 1 550 nm. It would provide an efficient alternative technology for the short wavelength infrared detector through coupling the up-conversion fluorescence screens to the CCD cameras.
2014, 43(12): 3877-3882.
The calculation of missile plume flow field provides basic data for that of the infrared radiation field. The formation of missile plume flow field was mainly studied, and the model of plume flow field was bulit according to the theory of combustion, fluid mechanics, gas dynamics, and considering the chemical reaction of combustion in the combustion chamber, the key parameters of flow field: velocity, temperature and pressure fields of data were given by combining Gambit and Fluent. The result whose residual was less than 1e-5 was obtained after more than 2 000 times iteration in Fluent. Velocity and pressure fields were in line with the actual situation, the temperature field's calculation error was 2%. The results show that the plume flow model can reflect the main features of flow field plume, and it can quickly provide the data results which the designer wants to get. It's able to provide basic data for the calculation of missile plume infrared characteristics, improve the accuracy of the plume, and save simulation time.
2014, 43(12): 3883-3888.
On the basis of the luminance contrast between target and background, the model of luminance fusion under the condition of infrared irradiation was established and then the condition of luminance fusion was obtained. According to different combinations of target and background in infrared detection, the applicable objects under the condition of infrared irradiation were studied and the conclusion was verified through the simulation of different combinations. The results show that the method of realizing the luminance fusion by infrared irradiation is suitable for bright objects with higher emissivity and dark objects with lower emissivity than background. Especially, when target's temperature is equal to background's, the infrared radiation realizing the luminance fusion on one band is equal to the radiation remittance of blackbody with the same temperature on the same band. In the end, the experiments were carried out with real infrared irradiating system irradiating different combinations of target and background, including bright target and dark target. Experimental results show that the luminance fusion of target and background has been realized on the middle infrared band to a certain extent, illustrating the effectiveness of the proposed method.
2014, 43(12): 3889-3893.
With the rapid development of modern military space technology, the requirement of infrared detector is increasing, the requirement of infrared optical element will stricter at the same time. The preparation of anti-reflection and protective film on the substrate of ZnS were mainly studied. The coating method of dielectric and hard film were combined, through the comparative analysis of different materials, finally, the carbide germanium (Ge1-xCx) as transition layer which between media film and DLC would be selectted. Using electron beam and ion source assisted deposition technology to manufacture the dielectric film, and using magnetron sputtering technology to manufacture the transition layer, at the end of process the DLC will be prepared by chemical vapor deposition technique. The problems of stress matching, and integrate different sedimentary processes were solved, meanwhile a stable process preparation process was got. Finally, the anti-reflection and protective film were deposited which average transmitted is 92%, the hardness meets the requirements.
2014, 43(12): 3894-3897.
In different model tasks, the antijamming ability of swing scanning infrared earth sensor in electromagnetic interference environment needs assessment. The structural design of overall structure and the main parts of portable swing scanning infrared earth sensor's whole machine electromagnetic compatibility test dedicated performance testing were introduced in detail. This device is able to assess the performance of the whole earth sensor indicators, gives infrared radiation signal, comprehensive assessment on the optical, mechanical, electrical properties of products. The earth simulator in this paper adopts a project of replaceable earth diaphragm for two orbit heights 35 786 km and 21 500 km, and can afford two earth angles (17.46 and 26.54). In this paper, test equipment achieve simulating the earth of satellites in space have seen on the ground, for the satellite components infrared earth sensor testing performance on the ground.
2014, 43(12): 3898-3902.
Long-range surface plasmon polaritons(LRSPPs) which express characteristics of long distances and low-loss are very hot in the plasmonic devices field. In order to conduct deeply research on low noise amplification of spontaneous emission in the LRSPPs, a waveguide structure and its theoretical model of radiation low-noise amplifier were set up. Then this structure was verified through the simulation calculation of the electromagnetic field distribution, which indicated that short-range surface plasmon polaritons (SRSPPs) are evanescent in metal district by spontaneous radiation, the effective noise power of each unit bandwidth reached to 7.4710-4 fW/Hz, three times to common signal amplifier, which expressed THz signal, the decay of IR140 excited molecules is the process without radiation, in which 100 nm at self-radiative decay rate becomes the inflection point for SRSPPs and LRSPPs, and after the inflection point the radiation process is mainly affected by the spontaneous radiation of LRSPPs.These results not only clear the characteristics of LRSPPs, but also have significant reference value for other plasma models.
2014, 43(12): 3903-3906.
To enhance the generation efficiency of THz wave, the interaction between femto-second laser pulse and GaAs crystal was studied. Firstly, the phase matching in bulk GaAs crystal between femto-second laser pulse and the generated terahertz wave was studied, and the result showed there was no intersection point between the refractive curve of pump laser and that of the THz wave, which indicated phase matching could not be achieved in this structure. Four waveguide structures then were proposed, and the refractive index curves in 0.1~6 THz were calculated based on related theory of waveguide, and the transmission length of the THz wave in the waveguide was also analyzed via the parameters of absorbance and dispersion. The results illustrate the phase matching is enhanced in the waveguide structures, and the generation efficiency of THz wave is supposed to get a promotion. The work serves the theory evidence for terahertz generation based on the interaction between femto-second laser and GaAs crystal.
2014, 43(12): 3907-3911.
Based on the computer generated holography, the dislocation fringes caused by the interference between the vortex beam and the plane beam were obtained through simulation and expriment. The dislocation gratings were made by films which recorde these interference fringes. With our own designed optical path, 1-4 order vortex beam were obtained in the experiment. The experimental results show that radius of the vortex beam will increase gradually with the increasing the orders, which are consistent with the theoretical analysis. The second and third diffraction beams of the gratings are observed further in the experiment. The vortex beam of symmetrical intensity distribution can be produced when the center of incent beam overlaps with the cetnter of dislocation grating, otherwise, the distribution of the vortex beam will be asymmetrical if the center of incent beam does not overlap with the center of dislocation grating. This work provides theoterical and technical support for further development of the optical tweezers based on vortex beam as the trapping beam.
A switchable narrow line-width dual-wavelength erbium-doped fiber laser using cascaded multi- mode Bragg gratings incorporating a novel high-finesse ring filter was proposed and demonstrated. The ring filter was a ring filter composed of two optical couplers and a section erbium-doped fiber. Thanks to the gain generated by the erbium-doped fiber, the ring filter has a high fineness spectral. The incorpora- tion of the ring filter led to the suppression of undesirable modes in the dual-wavelength erbium-doped fiber laser (EDFL). An experiment was carried out, in which six kinds of narrow line-width dual-wave- lengths combination were generated. And 3 dB linewidth of each wavelength of 0.14 nm to 0.16 nm without the filter was narrowed to 0.05 nm with the high fineness filter.
2014, 43(12): 3918-3923.
Fiber -optic distributed disturbance sensor based on Phase -sensitive Optical Time -Domain Reflectometry (-OTDR) can achieve real -time intrusion detection on a large scale. As a critical component of the sensor, the parameters of the laser affect the monitoring length and the spatial resolution. In this paper, the theoretical analysis and the experiments about the influences of the laser source on the system was described. The investigation results indicate that the monitoring length increases with the rising of optical power of the laser, the pulse width and the modulation period; the spatial resolution decreases with the decline of pulse width. Based on the above analysis, the preferred selection of the laser parameters with different monitoring length is proposed. The theoretical analysis are proved by the experiments.
2014, 43(12): 3924-3927.
Ultrashort pulse source with high energy and tunable wavelength is highly demanded for a lot of applications. Amplified all-normal-dispersion(ANDi) mode-locked fiber laser with gain medium of Ybdoped fiber is a compact and excellent source that fulfills those requirements. In this paper, amplification of tunable ANDi Yb -doped mode-locked fiber lasers was experimentally investigated. The gain versus signal wavelength was analyzed. It was found that the maximum gain was obtained near 1 030 nm and the gain decreased as wavelength increased, due to the gain spectrum of Yb-doped fiber. The gain versus pump power was also investigated. Gain saturation and the effect of ASE noise on gain were observed. The spectral and temporal distortions of pulse seed induced by fiber amplification were discussed. The pulse was broadened slightlydue to dispersion. The spectrum was distorted by ASE noise and limited gain bandwidth. If the gain is large and the power of amplified signal is high, the spectrum will be broadened by the effect of self-phase modulation(SPM).
2014, 43(12): 3928-3931.
Two-photon absorption (TPA) in Si avalanche photodiode (APD) was investigated for infrared photon in 1550-nm telecom band with different frequencies, intensities, under different bias voltage. By measurement of the TPA efficiency for photon frequency from 186.3 to 196.1 THz in detail, it was found that it decreases when the photon frequency goes up while a certain optimal TPA efficiency is around 190.5 THz for the APD under test. It can be observed from the experiments that the TPA efficiency increases until a certain intensity (The peak value of light intensity in this experiment is less than 10 mW) and then it decreases.
2014, 43(12): 3932-3936.
Three typical non-metallic materials of the wood, marble and synthetic glass were carved by CO2 laser. The effects of laser parameters on the carving surface morphology were researched, optimizing the laser carving process parameters of non-metallic materials. The results show that the carved depth is gradually increased with the increase of laser power; for the wood and synthetic glass with low melting point, the lower laser power is beneficial to obtain the notch of the neat and beautiful edge, but too large laser power can make the wood appear black or even overburning phenomenon, and make the synthetic glass appear corrugated and uneven phenomenon; for the brittle marble with high melting point, the higher laser power results in the clear notch, the neat sharp edge and no slag formation, however, when the carving speed is too low, the carved edge is rough and not neat.
2014, 43(12): 3937-3940.
In order to eliminate the backscattering phenomenon of the infrared laser sport images, or make the distribution of laser spot's gray levels reasonable, a backscattering suppression algorithm based on the spot center of gravity and an algorithm for compensating the gray levels of a laser spot were proposed. The backscattering suppression algorithm was based on extracting the laser spot's center of gravity. Then, the radius of the laser spot can be determined. Finally, the gray levels of the image should be decided by the set threshold. The algorithm for compensating the gray levels of the laser spot was based on determining the laser spot's edge points. Then, the center of the laser spot can be calculated. After that, the center should be corrected through the intensity of regional energy, and the radius of the laser spot would be confirmed. Finally, the gray levels of the laser spot were adjusted through the laser spot's center and radius. The experiment results of these two algorithms and their analyses were shown. Research proves that the backscattering suppression algorithm can substantially eliminate the backscattering phenomenon in the laser spot image, and the distribution of laser spot's gray levels is improved. The images which are processed by the algorithms are suitable for further analysis in engineering experiments or real-time observation.
2014, 43(12): 3941-3945.
To investigate the influence of shock wave in laser shock processing with microscale on shocked surface, experimental research of copper with different energy and shock number was carried out in the paper, and surface topography was measured. The results show that plastic deformation induced by shock wave with microscale is the interactive effect of pressure in both axial and radial direction. Pressure in axial direction plays a dominant role nearby the centre of laser beam, the amount of the plasticity deformation increases with increament of laser energy and shock number; Pressure in radial direction plays a leading role nearby the periphery, region of plastic deformation in radial direction increases with increament of laser energy, and spot edge is significantly salient when laser energy is over 70 mJ; Plastic deformation in radial direction increases first and then decreases with increasement of shock number, bulging deformation at spot edge is serious when shock number is over 3 times.
2014, 43(12): 3946-3950.
For face 3D reconstruction, a color 3D reconstruction method was put forward based on RGB laser scanning system. First, the mapping relationship between the pix-coordinates and the world- coordinates was determined by using a calibration plate; and a standard color plate was used for calibrating the RGB color data, in which the value acquired by digital camera and the value provided by the standard color plate had fitted. Second, the face 3D reconstruction experiment was introduced in detail including the steps of scanning, calibration and image processing. And the face could be 3D reconstructed with color texture at millimeter scales. Then, the 3D data were matched by ICP method, and could be exported to other software as a 3D model. This method simplifies the algorithm of the calibration and 3D reconstruction, and the system is low cost which can be widely used for 3D reconstruction of many kinds of objects.
2014, 43(12): 3951-3957.
With the Time Delayed and Integration (TDI) technology continues to evolve, Charge Coupled Devices (CCD) with TDI feature has been widely applied to high-resolution earth imaging system. However, in the push-broom imaging process, imaging system using TDI technology would inevitably be affected by the image motion, finally leading to blur image. The reason of image motion caused by optical system distortion in the process of TDI imaging was analyzed, formula of the image motion value was derived, the influence of optical system distortion on Modulation Transfer Function was analyzed, and the relationship between image quality deterioration caused by image motion and distortion was studied. Degradation of National Imagery Interpretability Rating Scale (NIIRS) parameters 驻NIIRS caused by image motion that generated by distortion was calculated for the TDI imaging system of which focal length was 9 000 mm, integral stage was 96, grounding sample distance was 0.6 m, F/p was 1, SNR was 50:1. The results showed when the derivative value of distortion was 6.493, NIIRS would reach -0.162 4, and would affect the image interpretation requirements. Finally, for this space camera, the restriction value of D'() without affecting interpretation requirements was given. This research could provide a reference for optical TDI remote sensing system design.
2014, 43(12): 3958-3962.
In order to improve the optical performance of optical window in aerial remote sensor, thermal-optical evaluation to fused silica optical window surrounding hypersonic was analyzed. The flight environment of optical window was analyzed. Based on the theory of aerodynamics, the relation between convection heat transfer coefficient and mach number was calculated. The temperature distributing of optical window was simulated by heat flux density, the optical path difference caused by the temperature difference between the inner and outer surfaces was calculated, and the influence of thermal deformation of the optical window on optical transfer function was analyzed. The study result shows that the optical path difference caused by thermal deformation of the optical window is 130.5 nm, which is under 1/4. The simulation result meets the requirements of the optical design. The above result discussed in this paper can be used as a reference for other optical window designs.
2014, 43(12): 3963-3968.
LCTF (Liquid Crystal Tunable Filter) is one of the rapid developing technologies in recent years. LCTF has many advantages, such as high spectral resolution, wide spectral range and light mass, so it is used widely in hyperspectral imaging remote sensor for lunar exploration. Various temperature in Liquid Crystal of LCTF will cause larger deviation of double refractive index, and that will affect the imaging quality of LCTF spectral imager. Working conditions of LCTF imaging spectrometer were analyzed in this paper. With the consideration about LCTF working modes and working temperature requirements, thermal control system was designed for LCTF spectral imager. The simulation results show that the designed thermal control system can meet the design requirements and LCTF spectral imager can get clear image to get ready for lunar exploration.
2014, 43(12): 3969-3972.
Star sensor is a kind of attitude measurement system, which is used to measure the real-time posture of the aircraft. A new kind of optical system of star sensor based on CCD was designed. And the calculation of relevant parameters was carried out. This kind of optical system with wide field of view, wide spectra range and good imaging quality was realized in ZEMAX software. This optical system has an effective focal length of 50 mm, an F-number of 1.8, a field of view of 23 degrees, a spectral range of 500-850 nm and a primary wavelength of 680 nm. The capture probability of three navigation stars is up to 100%. The especial requirements of the spot, encircled energy, distortion etc. are all satisfied. Lateral color is corrected greatly. The value is 0.087 m .The system only contains 6 pieces of lens. The structure is not only simple and compact, but also easy to manufacture.
2014, 43(12): 3973-3976.
With the intensification of environmental air pollution degree, especially CO2 increasing, various countries pay more and more attention to monitoring of atmospheric environmental quality. High spectral and high resolution CO2 detector are corresponding got more and more attention. But the satellite-borne detector must satisfy the space environment to ensure imaging quality. Mounting seat as the key components of the detector, its design is reasonable or not, has a great influence on the precision of detector. Thus, three kinds of mounting seat structure were designed according to the requirements of the detector use and installation interface. The structure properties were compared in mechanical vibration environment and temperature increasing. The results derived from theory and experiment. The results show the first-order frequency of mounting seat can reach 82 Hz, the deflection between collimating mirror components and grating surface is less than 10, the deflection between imaging lens components and grating surface is less than 10. These results can meet design technical requirement. The effect of translational mounting seat structure relative to collimation mirror components and imaging lens components is the smallest. The results are less than 17 to ensure the imaging quality of detector in 4℃ temperature environment. The structure is reasonable and feasible. The structure can provide reference for support design of relative instrument latterly.
2014, 43(12): 3977-3982.
In order to realize detection requirements of panoramic aerial camera for ground target, according to its principle of work to design a set of indoor detection system with a performance of high precision, multi parameter for aerial camera. The overall scheme of system was given after the analysis of the performance and the work principle. The detailed design of the main components of the system, including far target simulation system-large field view parallel light pipe and dynamic graphic generation system structure is produced. Proposing the test method to core parameters of parallel light pipe and dynamic graphics generator, we made a actual test on this detection system, the result shows its performance meet the design requirements.
2014, 43(12): 3983-3987.
TMT (Thirty Meter Telescope) is a thirty meter Ritchey-Chr佴tien optical-infrared telescope. The Third Mirror (M3) is an elliptical flat mirror, whose aperture is 3.594 m2.568 m, and the weight is 1.8 ton. The M3 system reflects the light coming from the Secondary Mirror System to the science instruments located on the Nasmyth platforms, so the M3 system rotates and tilts as the telescope rotates about the elevation axis to track astronomical objects across the sky. Due to the M3 support system the mirror figure maintains a high precision. The specification requires that the RMS of the mirror surface figure will be less than /5(=632.5 nm) or the SlopeRMS will be less than 1rad. This paper took one of the conceptual designs as an example to illustrate the method of evaluating the SlopeRMS. The axial support system in this plan used an 18 points whiffletree structure while the lateral support system used an 8 points A-frame structure. The FE model was constructed in ANSYS. Then MATLAB was employed to carry out the data processing. In the data processing program, the rigid movement was removed at first. Then the elliptical mirror was normalized into a circle mirror and the defocus and the astigmatism were eliminated. In the end, the SlopeRMS of nine sub -apertures was calculated. This method for evaluating the mirror surface figure is different from the classic one for the primary mirror, but it is effective to evaluate the elliptical mirror surface figure indeed. This method is meaningful in mirror surface figure evaluation.
2014, 43(12): 3993-3997.
To achieve good performance with short length, an ultra-thin cell phone lens was designed with optical plastic as lens material by optimizing the initial structure. The lens included four pieces with even aspheric, and the aperture was placed in front. The length of the lens was 4.49mm, the F number was 2.4, the viewing angle was 65.5, and the focal length was 3.71 mm. The MTF at the Nyquist frequency and half-Nyquist frequency of the detector was respectively greater than 0.14 and 0.46 and distortion of the lens was less than 1.5%. The RMS radius of different fields was less than 3.5 m. The CMOS sensor IMX111 from SONY was adopted, and the maximum resolution was 3 2642 488. By simulation, the defocusing amount of the cell phone was 144 m. By focusing, high quality images can be obtained when the object distance was greater than 10 cm. Through the sensitivity analysis, the tolerance of the lens met the processing requirements. With short length and aspherical plastic lens, the production cost is low, the imaging performance is good, which meet the practical requirements of cell phone lens.
2014, 43(12): 4006-4012.
Mixed contact fixed abrasive processing was proposed in this paper for controlling the grinding depth of a definitive tool and decreasing the tool switches frequency for the first time. Thus the machining efficiency can be significantly improved. The transient isotherm hydrodynamic lubrication equations of the liquid membrane between the tool and workpiece were established. Then explicit difference algorithm was adopted. The numerical simulation was conducted to analyze the hydrodynamic pressure and its distribution. The feasibility of controlling the grinding depth by the liquid membrane's hydrodynamic pressure was confirmed by the results. Because the hydrodynamic pressure increases with decreasing maximum grinding depth and its distribution becomes flat. The hydrodynamic pressure obviously increases with the inlet pressure, while its distribution becomes uneven. The influence of the rotational speed is inconspicuous, because of the grinding tool surface topography and the processing quality demand.
2014, 43(12): 3988-3992.
To investigate the cutting mechanism of the titanium alloy TC4 in the ultra-precision cutting process, an orthogonal cutting finite element model was established. The key techniques of modeling the FEM model and the material model were introduced detailed. The ultra-precision cutting process of titanium alloy was simulated using the established FEM model. The chip formation, cutting force and cutting temperature were obtained. To validate the simulation, an ultra-precision turning experiment has been carried out by single point diamond turning machine. Through the comparison of chip formation and cutting force, the result of simulation agrees with the result of experiment. It proves that the FEM method is an effective method can be used to investiate the ultra-precision cutting mechanisms of titanium alloys.
2014, 43(12): 3998-4005.
A 3-DOF flexure optical mount was designed to achieve elastic mounting and precise adjusting for small optics. Its mechanical properties were studied analytically. The mechanical model of the optical mount has been established based on its working principles. The stiffness formulas of each DOF were deduced and validated by finite element analysis (FEA). The mechanical properties influenced by structure parameters were analyzed and the methods to reduce parasitic motions were discussed based on the stiffness formulas. The structure design, parameters optimization, and mechanical performance stimulation were carried out for a mirror plate with clear aperture of 135 mm. The comparative results between analytical studies and FEA show that the relative errors are 5.5% and the stiffness formulas have sufficient accuracy. The analysis results also demonstrate that the analytical model and calculations are correct. The conclusions of mechanical analysis of the 3 -DOF flexure optical mount have theoretic significance for its structure design, mechanical performance analysis, and parameters optimization.
2014, 43(12): 4013-4016.
Terahertz modulator plays an important role in the development of terahertz technology. Optical transmission efficiency of subwavelength metallic hole arrays can be much higher because of the excitation of surface plasmon polaritons, and a higher modulation depth could be obtained by using this structure. A terahertz modulator based on subwavelength metallic hole arrays controlled by optical pump was demonstrated. Firstly, the principles of our sample were researched. Secondly, two -dimensional subwavelength metallic hole arrays were fabricated on semi -insulating GaAs substrate. Lastly, utilizing the terahertz time domain spectroscopy system, the transmission of terahertz radiation through subwavelength hole arrays was measured. Experimental results show that extraordinary optical transmission is excited by subwavelength hole arrays, and optically pumping reduces the terahertz transmission. A higher modulation depth is obtained at special frequency. This research can be the reference to the design and fabrication of terahertz modulator with high modulation depth.
2014, 43(12): 4017-4022.
A reflective Sagnac interferometer-type fiber optical voltage sensor based on the converse piezoelectric effect of quartz crystal was demonstrated. The sensor head consisted of two polarization- maintaining fiber sections with equal length bonded to the circumferential surface of each quartz transducer. The two fiber sections were spliced by 90 to balance differential group delay induced by the intrinsic birefringence. A non-reciprocal faraday rotator was utilized to interrogate the quasi-in-line Sagnac-type reflective interferometer. The principle of the sensor was investigated and the expression of the interference was deduced by using Jones Matrix. The linear relationship between the detectable phase and the voltage to be measured was confirmed by analyzing the mathematic model of sensor head and the scale factor of the sensor was calculated associated with the digital closed-loop model. The experiment shows that the nonlinear error of the scale factor is less than 0.2% when the measured voltage is more than 3 000 V.
2014, 43(12): 4023-4027.
Based on the electrically controlled birefringence of the liquid crystal and the photonic crystal self-collimation effect, a tunable Mach-Zehnder interferometer filter structure was designed by introducing complex defects in the two-dimensional photonic crystal. The mathematical model was established between the applied voltage and the effective refractive index of the liquid crystal with applying free energy theory of the liquid crystal. Based on the phase modulation principle of Mach-Zehnder interferometer and the theory of the equivalent refractive index of the photonic crystal, the effect of the electrically controlled birefringence of the liquid crystal on output spectra of Mach-Zehnder interferometer filter was theoretical analyzed, and the output spectra of the filter was simulated with finite difference time domain method. And according to the simulation results, the cascaded optimization of the structure was designed. The results show that by controlling the applied voltage can change the transmission wavelength of output and achieve the effect of tunable filter. After level cascaded, the filter effect has a significant improvement. The filter bandwidth of a half-wave reduced from 20 nm to 7 nm, and the tuning range was increased from 15 nm to 40 nm. Therefore, the filter can more optimization by means of further cascading of the structure, in order to used in the optical wavelength division multiplexing system.
2014, 43(12): 4028-4034.
Terahertz technology is a new across research field. In the last twenty years, THz technology has a great development. The multiplier was the very important aspect of the technology of terahertz heterodyne receiver front-ends in astrophysics, planetary and atmospheric sciences. THz gap exist in the application due to the lack of effective THz signal sources and detectors. Through the frequency multiple and amplification, we can get a high stability, low phase noise THz multiplier sources. 340 GHz is one of terahertz atmospheric windows, so 340 GHz multiplier source can be used in variety systems including communication and imaging system. The planar schottky diode based multiplier could work at room or low temperature. Multiplier was the most important part in terahertz multiplier chain. In this article, we have designed a 0.34 THz multiplier combined analysis of electromagnetic field theory and three- dimensional electromagnetic simulation software HFSS and ADS. The experimental results show that the max output is about 4.8 dBm, the max efficiency was 3%, in 331-354.5 GHz, and the output power was above 0 dBm. The results proved the correctness of the diode model and simulation.
2014, 43(12): 4035-4039.
Low temperature bonding for quartz glass as a reliable solid connection technology has received extensive attention in developed countries in Europe and America, and has been widely used in many fields such as aerospace, basic research, strong laser etc.. Low temperature bonding based on hydroxide-catalyzed hydration/dehydration at the glass surface is a low temperature bonding method with high breaking strength, high precision and high reliability by forming three-dimensional silicate networks at the interface. The physical principle and the basic process of low temperature bonding was demonstrated and the low temperature bonding for quartz glass was realized too. The results of the bonding interface of environmental adaptability test show that, compared with conventional optical contact method, low temperature bonding is superior in bonding strength and adaptability in temperature shock environment and water environment, while low temperature bonding matches optical contact in uniformity, precision, transparency, vacuum seal and adaptability in regular temperature environment and vibration environment.
2014, 43(12): 4040-4044.
It will be helpful for soft X-ray Spectrometer that X-Ray diode (XRD) can be improved to be more compact. And it will be convenient that other X-ray diagnosis apparatus integrate the mini - XRD. A new XRD with smaller cathode was designed, which owned more reasonable capacitor for power storage and smaller size. Microwave performances of the output part were simulated. The results show that signal distortion and reflection is ignorable in the range of 0 -20 GHz and experiments requirements can be satisfied. And detector character test experiments were carried on the short pulse laser equipment. Data indicates that capability of temporal resolution was improved by 20%. Because of the study of detector with smaller cathode area, XRD will be more popular for estimating of X-ray flux.
2014, 43(12): 4045-4050.
Diamond abrasives were coated by electroless plating. Fixed abrasive pads(FAP) were prepared by using diamonds with different Ni covering ratio. The morphology of coated diamond abrasives were observed by scanning electron microscopy. The effect of Ni covering ratio on coefficient of friction(COF) and acoustic emission(AE) during the lapping process were investigated. Material removal rate(MMR) and surface roughness of K9 glass lapped by FAP with abrasives with different Ni covering ratio were compared. The results demonstrate that morphology of abrasives changes significantly with Ni covering ratio. COF, MMR and surface roughness increase first then decrease with the increase of covering ratio. Friction force between pad and work-piece, and cutting depth of abrasive grain into the work-piece are the highest when Ni covering ratio is 50% and the FAP exhibits a characteristic of self-conditioning. The MRR and its stability are the best when FAP embedded with diamond abrasives with a Ni covering ratio of 50%.
2014, 43(12): 4051-4055.
Air-core photonic crystal fiber is a new optical fiber used in fiber-optic gyroscope, which has better diamagnetic than traditional optical fiber. Magnetic-field sensitivity of the fiber is characterized by the Verdet constant of the fiber. In order to study the magnetic-field sensitivity of air-core photonic crystal fiber, Comsol software was used to simulate the Verdet constant of HC-1550-2 air-core photonic crystal fiber in this paper. At the same time, a dual-optical system including a Faraday Rotation Mirror (FRM) was chosen to measure the air-core photonic crystal fiber's Verdet constant. In the system, the FRM can eliminate the influence of the linear birefringence in the tested fiber on measurement. The measured results are in agreement with the simulation results. It can be seen from the results, Verdet constant of air-core photonic crystal fiber is nearly 1/100 of the traditional optical fiber, which verifies that air-core photonic crystal fiber has the advantages on decreasing the magnetic-field sensitivity.
2014, 43(12): 4061-4065.
Resonator fiber optic gyro (R -FOG) is a novel optical sensor whose resonant frequency changes due to the Sagnac effect. The closed loop frequency locking system can decrease the effect of temperature stress and other external environmental changes on fiber ring resonator and so improve the performance of the gyroscope. The design of closed loop frequency locking system where digital circuits and analog circuits were combined was proposed. It overcame the temperature drift in analog circuits, reduced A/D converter converting speed of system, also did not need complex digital demodulation algorithm. Using this design, locking frequency accuracy of 2.15 ()/s can be obtained in 10 s.
2014, 43(12): 4066-4071.
A new method to measure the beat-length in low-birefringence fibers was shown. The optical path was consisted of an amplified spontaneous emission (ASE) light source, a fiber Fabry-Perot tunable filter, two linear polarizes, the measured fiber and a phase compensation plate. Phase detection was chosen to reduce the error from environment influence. Phase compensation plate was applied to ensure the testing system always sensitive to the change of phase. The testing system was set up and tested in reality. The system performed well in the repeated test. It is simple and has no strict demand on these equipments. There is no limitation on the configuration and the length of the measured fiber. It is reliable for fibers witch's beat-length is up to 20 m. The beat-length precision of the measurement is 1%.
2014, 43(12): 4072-4077.
The Four Wave Mixing(FWM) of the quantum dots semiconductor optical amplifiers(QD-SOA) was investigated by using the finite differential method based on the transitions between energy levels. The effects of the parameters on the efficiency of FWM were analyzed by simulation. The efficiency of FWM increased with the increase of the power of pump light, the length of QD-SOA and the injected current. The efficiency of FWM decreased with the increase of the power of the probe light and wavelength space. The exclusive-OR(XOR) logic of differential phase-shift keying signals was realized based on the FWM effect and the time domain and frequency domain results of the XOR logic were got by simulation. The XOR logics at position with different wavelengths were realized simultaneously. The XOR logic of 32-bit sequence was investigated and the XOR result and the eye diagram were achieved.
2014, 43(12): 4078-4081.
High -speed photonic signal source is absolute necessity for modern optical communications, which attracts more and more attention at present. By using a biased Mach-Zehnder modulator (MZM), a simple scheme based on frequency multiplication was presented and experimentally investigated for generation of high-speed microwave photonic signal. The phase difference of two beams in the MZM was adjusted by a DC bias applied on the MZM, which caused pulse splitting and frequency multiplication. In the experiment, a 5 -GHz RF signal source successfully generated double -frequency microwave optical signal (10-GHz) with great quality. It was also observed that different biased voltage would produce different pulse train, while the optimal bias was required for high -quality frequency multiplication. This scheme is available to generate high-frequency optical pulses over 40 GHz, which is promising to be widely used in microwave photonic communication.
2014, 43(12): 4082-4087.
Photonic crystal fiber-optic gyroscope(PCFOG) has become an important developing direction of FOG due to its low magnetic sensitivity, good temperature stability, and anti -radiation capability in principle. Researchers have studied a lot on the bias characteristics of PCFOG, however, no work has been done on its scale factor performance. In this paper, the factors that lead to scale factor error of PCFOG were analyzed and the error induced by photonic crystal fiber coil was experimentally tested. The results show that PCFOG has better temperature and radiation stabilities than ordinary FOG. Within a temperature range of -40~+70 ℃, the scale factor repeatability of the PCFOG is 242.310-6 without compensation which is almost half of the conventional FOG; After a total dose of 50 krad (Si) radiation, the scale factor shifts 10910-6 and no notable changes are observed with the repeatability and nonlinearity. Therefore, the PCFOG shows one time better stability than conventional FOG.
2014, 43(12): 4056-4060.
As a key component of the polarization-maintaining fiber optic gyroscope, the fiber coil is sensitive to the temperature which mainly shows that producing thermally induced nonreciprocity phase shift. To overcome this problem, a novel thermally induced nonreciprocity phase shift measurement method based on strain distribution was proposed in this paper. The strain distribution data of fiber coil at different temperatures was analyzed, and the model of optical path centering was established. Modifying the pigtail of fiber coil with the model, and the optical symmetry properties can be adjusted consequently. In order to verify the effect of our work, the modified pigtail was equipped to the gyroscope to test its performance, and the result shows the accuracy of the gyroscope becomes much better than before. The method proposed in this paper is helpful to increase the yield rate of fiber coil, and it also has the advantage of easy to carry out.
2014, 43(12): 4088-4093.
In order to prompt the positioning precision for three -dimension target, a compound eye system is introduced, and the process that the multi-eye of compound eye influences on the positioning precision was analyzed, and the simulation analysis was finished. Firstly, a compound eye as the positioning system was introduced. Subsequently, the optical model of incident ray from target to imaging lens was built. Next, three-dimension coordinates of special target array points are set. According to the three-dimension coordinate of each target point and the three-dimension coordinate of its imaging lens, the incident angle from the target to its imaging lens was solved. Then, the corresponding relation between every incident angle and its imaging point coordinate was established as the calibration result of the imaging system. Finally, the three -dimension coordinate of a target point was solved with various sub-eyes according to the calibration result. The simulation results show that the compound eye system with multi-eye could provide higher positioning precision, and the more sub-eyes, the higher precision. The scheme can guide the manufacture of compound eye for target positioning with high precision and expand its applicable range in the further.
2014, 43(12): 4094-4099.
In order to realize position-pose measurement of hand-eye camera,an measurement accuracy test system was established. Firstly,based on the target design forms and P3P algorithm, position-pose measurement principle was presented. Sencondly, the position measurement accuracy and pose measurement accuracy were analyzed in theory, i.e., the translational position measurement accuracy along the X axis of the target and the rotational pose measurement accuracy about the X-axis, Y-axis and Z-axis of the target. Thirdly, the usual test method was presented, a new test way to achieve six degree of freedom by relative position -pose production was proposed. Root mean square error was introduced as an evaluation for measurement accuracy, and the test method was described in detail. Finally, practical test for measurement accuracy of an hand -eye camera was carried out, and the experimental data was compared with the theoretical data. The experimental results indicate that the maximum measurement accuracy for distance is 25.60mm and the maximum measurement accuracy for rotation is 1.4. It can satisfy the system requirements for accuracy.
2014, 43(12): 4100-4104.
The Simultaneous Imaging Polarimetry (SIP)is a new type of remote sensing detection technology. The imaging polarimetry architecture refered in the paper is Division of Amplitude, which can simultaneously obtain four polarization intensity images (in the orientation angle of 0,45,90 and 135 degree)of the same target on the same detector. Affected by self -polarization, error of polarization element and coating of the system, the orientation angle of polarization will be deviated. In order to ensure the polarization measurement accuracy, the orientation angle of polarization was calibrated using two methods (Equator-Poles calibration and curve fitting). Results show that the difference between these two methods is less than 0.4%, and degree of linear polarization (DOLP) accuracy of measurement and principle calculation is all within 2%, which prove the effect of the calibration.
2014, 43(12): 4105-4110.
There are certain deficiencies in detection methods on the traditional electric locomotive contact wire geometry parameters. Based on the testing requirements and image characteristics of the worn wire, the integrated measurement method of online, non-contact, multi-parameter was proposed based on binocular vision technology. In-depth theoretical analysis had been conducted on image edge detection based on LOG algorithms, on which new methods of edge location by means of energy center algorithm were proposed, and numerical simulations were conducted. Simulation results show that the algorithm of energy centers has got stronger anti-jamming and anti-blur capabilities, with higher positioning accuracy. Verification experiments are carried out by using round steel with different heights, stagger values and wear widths as the detection object, and it is compared with the results tested by the laser rangefinders and digital display vernier calipers. Experimental results show that the edge detection by means of energy center algorithm is more accurater than LOG algorithms. Simultaneously, the measurement method proposed in this paper has smaller indication errors, better reproducibility, and it can meet the integrated needs of online, non-contact testing on the contact line.
2014, 43(12): 4111-4116.
The atmospheric phase delay caused by tropospheric water vapor is an important factor to the precision of repeat pass InSAR. In order to solve the problems in InSAR atmospheric phase delay effectively, the atmospheric delay error of InSAR was analyzed, and the atmospheric correction methods and key technology using MODIS water vapor data for ASAR interferograms were presented. Then, the atmospheric corrections was conducted using ASAR interferometric pair over the Taiyuan region as examples. The experimental results show that the quality of interferogram can be improved greatly by the MODIS/ASAR atmospheric correction method, and the deformation inversion accuracy can be significantly improved, the necessity and reliability of MODIS and ASAR data fusion form obtaining information of surface deformation are aslo verified.
2014, 43(12): 4117-4122.
In order to realize the velocity measurement of moving solid-surface, a novel spatial filtering velocimeter based on linear image sensor was established and a new method was proposed to ensure the error source of the system. The image sensor was employed both as a detector and as a pair of differential spatial filters so that the system was simplified. The spatial filtering characteristics of the linear image sensor were investigated theoretically and the driving circuit and the signal acquiring and preprocessing circuit were designed. The velocity of a conveyor belt using a high-precision turn table as the driving wheel and the radiating frequency of a lamp were measured. The experimental results show that the measurement error of velocity of conveyor belt was within 0.77% and the measurement uncertainty within 11 minutes was 0.66%; the radiating frequency of a lamp was measured under the condition of no imaging system, and the measurement uncertainty turned out to be 0.056%, which was an order better. In a word, the velocimeter can satisfy the requirements of non -contact, real -time, high precision and high stability velocity measurement of a conveyor belt.
2014, 43(12): 4123-4127.
The angle errors of high precision reference encoder deeply influence the precision of small size absolute photoelectric encoder's detection equipment. There are many factors that influence encoder's errors which can't be described by mathematical model. So in this paper, a method using RBF networks was proposed to amend errors. Firstly, the method used several kinds of polyhedron to detect the reference encoder with collimator, so that it could get more points of errors, and the errors were composed in one coordinate curve. Secondly, the RBF networks were built by using the result of error detection, in order to make their outputs closed to the true angle. Lastly, the reference encoder applied in small size absolute photoelectric encoder's detection equipment was compensated by the circuit of compensation. The experiments show that the circuit is fast, convenient and not influenced by the complexity of networks. The precision of encoder is improved 2 times, and this method improves the precision of detection equipment.
2014, 43(12): 4128-4132.
In order to improve the performance of the FOG, the suitable fiber coil were chosen through the fiber coil strain distribution measurement. In this article, the impact of fiber coil non-reciprocal on the gyro output which generated by strain were studied. Based on the analysis, the strain of fiber coil was tested and the appropriate samples for FOG were selected using the fiber strain analyzer to assemble and install the selected fiber coil for bias experiment. The results show that, strain tests are effectively carried out and the appropriate samples were selected using the strain analyzer. Performance of FOG has been significantly improved with the measurement and select of fiber coil strain distribution, bias stability over the full temperature range is up to 0.08 ()/h, which has important guiding significance for the development of high precision FOG.
2014, 43(12): 4133-4139.
It's becoming a research hot topic that two axis opto-electrical tracking instrument is loaded on satellite to continuously track and observe moving target in space. At present, there are Space-Based Space Surveillance System (SBSS), Space Tracking and Surveillance System (STSS) and Precision Tracking and Surveillance System (PTSS). In order to deal with stable tracking control technology for opto-electrical axis on the condition of dynamic platform on satellite, firstly, simplifying physics model of opto-electrical tracking control system on satellite. Secondly, solving relative angular velocity and acceleration between two satellites near sun-synchronous orbits. Thirdly, analyzing active stable tracking control scheme and principle based on opto-electrical compound axis tracking control system. Lastly, establishing simulation model of opto-electrical compound axis tracking control system on satellite. And the results show that stable tracking precision is 2.5 for space object in the relative maneuvering range of (37.68 ()/s、47.33 ()/s) and space satellite that relative low velocity is 0.1 ()/s.
2014, 43(12): 4140-4145.
Horizontal parallax is one of important factors that affect 3D images comfortableness. 3D images of different horizontal parallax were used as stimulate signals, by recording the EEG signals, the ERP waveforms of 3D images were extracted. At the same time, behavioral data of comfort experience of the 3D images was recorded and their comfort detection rate was calculated. EEG analysis result shows that no matter in the case of crossed or uncrossed horizontal parallax, comfort range of 3D images horizontal parallax is within 45'. When horizontal parallax is from 45'to 75', the ERP amplitude of around 280 ms is associated with the discomfort level of crossed parallax 3D images and the amplitude of around 250 ms is related to the discomfort level of uncrossed parallax 3D images; Detection rate curve and subjective evaluation results show that comfort range of 3D images horizontal parallax is within 45'. When horizontal parallax is from 45'to 75', the discomfort degree of 3D images is increased. Results show that EEG analysis, detection rate curve and subjective evaluation conclusion is consistent, so EEG can be used to analyze the effect of 3D images comfortableness on horizontal parallax.
2014, 43(12): 4146-4152.
In order to evaluate the size of image noise of electron multiplying CCD (EMCCD) quantitatively and achieve an accurate estimation of the EMCCD image noise parameters, the ECMMD noise distribution and its parameter estimation methods were studied. Firstly, the sources and statistical properties of EMCCD noise were discussed, and thereby an EMCCD noise distribution model was established. Then two EMCCD noise parameter estimation methods --the moment estimation method and the Gauss -Newton method were proposed and Monte Carlo simulation was done to verify their performance. The results show that both the average relative error and the relative standard deviation of the two methods are of 10-2 magnitude, presenting high estimation accuracy, and the Gauss -Newton method get better performance. With integration time of 50 s, a series of EMCCD images of the dark field with no gain and images of the background with gain of 50 were obtained. Using the moment estimation method and the Gauss-Newton method, the dark current noise, clock induced charge noise and readout noise were estimated. The results present that the estimated value is consistent with the EMCCD index value, which proves the moment estimation method and the Gauss -Newton method are able to estimate the noise parameter effectively and has a high accuracy.
2014, 43(12): 4153-4158.
In the present study, Pingluo of Ningxia Province in China was taken as the study area, and spectral data obtained by Unispec-SC, the value of soil salt content measured by experiment were taken as the basic data. Hyper-spectral data processing method was used to analyze spectral characteristics of different levels of salinization area vegetation. Spectral data were transformed in 16 different approaches, including logarithm, root mean squares, and first order differentiation. Correlation analysis was carried out between the obtained spectra and soil salinity. The most sensitive bands was selected, soil index and vegetation index were built. Nonlinear regression was employed to establish soil salinization remote sensing monitoring model. The results show that by comparing various spectral transformations, the first order differential of soil spectral was the most sensitive to soil salinization degrees. The model was based on the spectral index, including SI and MSAVI, and it could monitor soil salinization accurately. The correlation between simulated values and measured values was 0.758 9. The soil salinization could be achieved rapidly in the area.
2014, 43(12): 4159-4163.
In order to more accurately estimate noise intensity for hyperspectral imagery, the paper proposed a noise estimation algorithm based on relevance vector machine(RVM)for hyperspectral imagery. And the algorithm that used RVM regression, residuals and noise was studied. First of all, this paper introduced the characteristics and shortage of spatial/spectral dimension decorrelation in noise estimation that used widely nowadays for hyperspectral imagery. Then, the nonlinear regression analysis of RVM was introduced. And the residuals will be too large, when there was a strong nonlinear correlation in the system for spatial/spectral dimension decorrelation. To this problem, the paper proposed a new method that used RVM regression to remove strong signal correlation and used the residual images to estimate the noise, so as to improve the stability of the assessment system. Experimental results indicate that the precision of the noise intensity is better than 8%, and show that the method is more effective compared to the traditional method. It concludes that the RVM can satisfy the system requirements of higher precision and stabilization in noise estimation for automatic hyperspectral imagery.
2014, 43(12): 4164-4169.
To address the challenging problem of robust background subtraction under sudden illumination changes, a novel foreground segmentation method based on feature fusion was proposed. The method consisted of three stages. First, a scene model through integrating the global illumination function into the framework of Gaussian mixture models was built. Second, three kinds of illumination invariant features, i. e. zero mean normalized cross -correlation (ZNCC), textures, and contours, were extracted from the current frame image. Third, the illumination invariant features were combined for foreground segmentation in two steps. Specifically, the ZNCC and textures were combined in the first step, and the contour was integrated in the second step. The experimental results show that the proposed method can effectively improve the accuracy and robustness of foreground segmentation.
2014, 43(12): 4170-4176.
Since chaos is sensitive for initial values, it is very suitable for data encryption. An image encryption algorithm based on hyper-chaotic control parameters and mixed scrambling diffusion structure of higher -order chaotic system was presented. The encryption algorithm included scrambling step and diffusion step. In the scrambling step, the composite chaotic map was used to generate the alignment phase control parameters and scramble for the high-level image cross -correlation between the adjacent pixels. In the diffusion step, the composite chaotic map with the different initial states and parameters was used to generate the initial conditions for hyper-chaotic cellular neural networks in order to generate the key stream. This method was evaluated by known plaintext attack and chosen plaintext attack, key space, image histogram, and simulations show good results. Compared with several other related algorithms, it has better anti -aggressive and key sensitivity is high. It can be applied to the image encryption.
2014, 43(12): 4177-4185.
Airspace covering blind area and Doppler blind zone occur as single airborne early warning (AEW) radar is operated to probe targets. The parameterized mathematical model of AEW radar patrol routes was established. The calculation formula of AEW radar target detection probability was derived. And the patrol routes optimizing criterion of single AEW radar was proposed based on the 2-norm of accumulated detection probability matrix. The mission routes programming problem of multi-AEW radar cooperation probing was studied further and the optimizing criteria was presented in that multi -AEW radar cooperation can help reduce the bad influence of airspace covering blind area and Doppler blind zone on detection performance. Finally, the effects of time interval and distance separation between AEW radars on accumulated detection probability of the key surveillance area were analyzed. Simulation results show that the optimizing criteria founding on 2 -norm of accumulated detection probability matrix are effective which are conducive to maximize the coverage and target detection probability of AEW radar.
2014, 43(12): 4186-4191.
When observation distance and angle change, angular distortion and scale distortion of target image relative to the template will appear, which limits the development of pattern recognition with correlation recognition technology. The Maximum Average Correlation Height (MACH) filter was applied to recognize distorted targets in this paper. According to multiple computer simulation experiments and optical experiments, the filter has the characteristcs of high distortion tolerance and bright correlation peaks by optimizing the control parameters of the synthesized filter. Distorted targets were filtered in frequency domain by the improved MACH filter, correlation peaks could be sharpened effectively and recognition scope was expanded succesfully. As a practical example, computer simulation experiments and optical experiments for warship in cluttered scene were carried out. The experimental results prove the feasibility of the algorithm.
2014, 43(12): 4192-4197.
The texture feature based methods are widely used for face recognition. However, as the texture feature relies on the high frequency details of the image, the performance of a method that merely utilizes texture feature deteriorates drastically when the image is blurred. To overcome this defect of the texture feature, a method fusing color and texture features was proposed for blurred face recognition. This method extracted a type of facial color feature using an opponent color model which was in accordance with the human visual mechanism. This type of color feature and a certain type of texture feature were used for recognition separately, and then their similarity scores were fused to make final decision. The color feature is a description of the low frequency components of the image, which is robust to image blur and complementary to the texture feature. Experiments on the FERET and AR face databases show that the recognition performance for blurred face image is effectively improved by fusing the color and texture features.
2014, 43(12): 4198-4203.
With the integrated perception system of IR camera and 3D lidar, the calibration based on feature point matching was studied and the thermostat heating hollow net was designed to provide feature points. Infrared image feature points were extracted by Harris corner detector. To decrease the influence from mixed pixels, plane fitting of heating net and plane conformity check of laser points on net were used to locate the edges in depth image. Edges'average value at corner was calculated to extract depth feature point. At last, NMSM-EM method was adopted to optimize the result. The research results show that the integrated perception system can accurately perceive mobile robot's running environment in dim light.
