Journals >Infrared and Laser Engineering
Contents
2005
Volume: 34 Issue 4
29 Article(s)
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Research Article
Design of hybrid refractive/diffractive off-axial optical system for multispectral infrared imaging spectrometer
[in Chinese], [in Chinese], and [in Chinese]
The magnification changing with the incident wavelength, which would bring the different spectral image matching error, is inevitable in the multispectral infrared imaging spectrometer using binary optical element (BOE) as spectro"element because its focal length changes with incident wavelength. To improve the opThe magnification changing with the incident wavelength, which would bring the different spectral image matching error, is inevitable in the multispectral infrared imaging spectrometer using binary optical element (BOE) as spectro"element because its focal length changes with incident wavelength. To improve the optical performance of the multispectral infrared imaging spectrometer, the hybrid refraction/ diffraction zoom optical system combining the off"axial three"mirror system is firstly put forward. The front element of multispectral infrared imaging spectrometer is an unobscured and afocal three "mirror telescope,which not only makes for enlarging the clear aperture of multispectral infrared imaging spectrome" ter,but also reduces the size and weight.The rear elements of multispectral infrared imaging spectrometeris a hybrid refractive/diffractive three#elements zoom optical system, which eliminates the different spec-tral image matching error in the multispectral infrared imaging spectrometer using BOE aThe magnification changing with the incident wavelength, which would bring the different spectral image matching error, is inevitable in the multispectral infrared imaging spectrometer using binary optical element (BOE) as spectro"element because its focal length changes with incident wavelength. To improve the optical performance of the multispectral infrared imaging spectrometer, the hybrid refraction/ diffraction zoom optical system combining the off"axial three"mirror system is firstly put forward. The front element of multispectral infrared imaging spectrometer is an unobscured and afocal three "mirror telescope,which not only makes for enlarging the clear aperture of multispectral infrared imaging spectrome" ter,but also reduces the size and weight.The rear elements of multispectral infrared imaging spectrometeris a hybrid refractive/diffractive three#elements zoom optical system, which eliminates the different spec-tral image matching error in the multispectral infrared imaging spectrometer using BOE as spectro element The designed system is very simple in structure. Moreover, the modulation transfer function (MTF) of the designed system is greater than 0.3 for 20 c/mm spatial frequency, which meets the resolution requirement of the stare array detector of the multispectral infrared imaging spectrometer. In addition, the image size of the designed system is 7.2 mm, which meets 25 μm detector cell and 128 ×128 infrared detector arrays..
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 379 (2005)
Optical director design of IRST system
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
An optical director design of the infrared search and track （IRST） system is proposed. After analyzing characters of the IRST system and its optical director,the compositions and functions of the optical director of the IRST system are described.IRST system requires a large search field, a short search period and respoAn optical director design of the infrared search and track （IRST） system is proposed. After analyzing characters of the IRST system and its optical director,the compositions and functions of the optical director of the IRST system are described.IRST system requires a large search field, a short search period and response time. In order to get these effects, this scheme scans the search field with mirror polygon combining overturn mirror, by this means,it is able to meet all demands of an IRST system. With regard to the control system,different electromotors, encoders and control methods are applied according to different requirements for position and speed of each component to reduce volume and cost at the same time to meet the precision demand.Testified by experiments, this infrared optical director has advanced technology and rational scheme and can well meet all demands of an IRST system. The experiments of searching targets have excellent results. An innovation of this paper is that it resolves effectively the conflict between the demand for the large-field and rapid search and the demand for the small volume and the low cost..
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 384 (2005)
Application of athermalisation in optical systems
[in Chinese], [in Chinese], and [in Chinese]
This paper focuses on the temperature effect and its solution. Analysis is made concerning temperature effect on three factors: refractive index of optical elements, curvature radius and center thickness of optical elements, and the space distance between optical elements, and their relation to temperature variation arThis paper focuses on the temperature effect and its solution. Analysis is made concerning temperature effect on three factors: refractive index of optical elements, curvature radius and center thickness of optical elements, and the space distance between optical elements, and their relation to temperature variation are as well discussed. Athermalisation is introduced to eliminate the influence of temperature in optical systems, and the advantage and the disadvantage of the three athermalisations used currently are compared. An infrared optical system is taken for example. In the design process, the mechanical active athermalisation is used for eliminating the influence of the temperature change . And the image quality comparison with/without athermalisation is made. It is concluded that the influence of temperature effect could be eliminated so that the high image quality could be realized in a wide temperature range..
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 388 (2005)
Athermalizing infrared optical systems by using simple mechanical framework
[in Chinese], and [in Chinese]
In order to describe principle and method of the athermalizing technique using simple me- chanical framework in this thesis, firstly, three ways of athermalizing of infrared optical system are com- pared.Secondly, an optical system working at 3～5 μm, 3°field of view and - 40～60 ℃ temperature range was designed. FuIn order to describe principle and method of the athermalizing technique using simple me- chanical framework in this thesis, firstly, three ways of athermalizing of infrared optical system are com- pared.Secondly, an optical system working at 3～5 μm, 3°field of view and - 40～60 ℃ temperature range was designed. Furthermore, the image quality approaching the diffraction limit in a larger spatial field view and wider thermal range can be obtained when simple mechanical framework is used in the optical system..
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 391 (2005)
High performance infrared antireflection films on ZnSe substrate for 8～12 μm
[in Chinese], and [in Chinese]
In order to enhance transmission rate and mechanical intensity of ZnSe, the design and de- position of high performance infrared antireflection films on ZnSe substrate by ion beam assisted deposi- tion are discussed. The choice of films materials and the design of films system are introduced.The mea- sured spectral curIn order to enhance transmission rate and mechanical intensity of ZnSe, the design and de- position of high performance infrared antireflection films on ZnSe substrate by ion beam assisted deposi- tion are discussed. The choice of films materials and the design of films system are introduced.The mea- sured spectral curve of 8～12 μm wavelength range antireflection films deposition by this method has been given. The experimental results show that the films have good characteristics such as a peak transmi" ssion of more than 99%,an average transmission in the designed wavelength range of greater than 98%, good adherence and stability of optical and mechanical properties. These are important for the application of infrared optical system..
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 394 (2005)
Interferogram region spreading technology in spatial domain
[in Chinese], [in Chinese], and [in Chinese]
The kernel of modern interferometry is to obtain necessary surface shape and parameter by processing interferogram with reasonable algorithm. The circular interferogram must be spread into square region when interferogram is disposed by using 2-D FFT arithmetic, which is applied only to numeric disperse data and requirThe kernel of modern interferometry is to obtain necessary surface shape and parameter by processing interferogram with reasonable algorithm. The circular interferogram must be spread into square region when interferogram is disposed by using 2-D FFT arithmetic, which is applied only to numeric disperse data and requires square distributing region.On the basis of the study of the basic principle of in- terferometry by using 2-D FFT arithmetic, the principle and method of interferogram region spreading is proposed.This technique has been used in region spreading of an actual interferogram with satisfactory re- sult. The results indicate that the method has high processing precision and establishes the foundation to phase recovery..
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 397 (2005)
Real-time detection of infrared spot based on FPGA
[in Chinese], and [in Chinese]
The infrared spot detection is the key technique used in optical measurement and detection instruments, such as infrared automation optometry, infrared range finder. The precision and speed of the detection algorithm affect those of the optical measurement system directly. The detection system is currently based on PC,The infrared spot detection is the key technique used in optical measurement and detection instruments, such as infrared automation optometry, infrared range finder. The precision and speed of the detection algorithm affect those of the optical measurement system directly. The detection system is currently based on PC, with the question of real-time and stability. There is a way to realize realtime detec-tion for low SNR infrared spot using FPGA based on gravity model. In test circuit, firstly,analog CCD video signal is converted to CCIR656 digital video signal using the video decoder chip SAA7113; secondly, in FPGA, a streamline structure is used for histogram calculating, binary image, five times eroding and five times dilating for filtering noise, then the coordinate of centre of cavity is calculated. The test circuit can finish the spot detection in one image in 1/25 s for PAL infrared spots video signal from infrared automation optometry, which was generated by retina reflecting. It requires about 1 s for finishing the above process for one normal PC. The scheme based on FPGA is presented..
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 401 (2005)
Polarizing beam splitter based on frustrated total internal reflection
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The existing status and main characters of thin- film polarizing beam splitter (PBS) are pre- sented and demonstrated. Frustrated total internal reflection and thin film interference are simultaneously employed to allow S- polarized light to be transmitted and P- polarized light to be reflected over a wide range of wavThe existing status and main characters of thin- film polarizing beam splitter (PBS) are pre- sented and demonstrated. Frustrated total internal reflection and thin film interference are simultaneously employed to allow S- polarized light to be transmitted and P- polarized light to be reflected over a wide range of wavelengths and angles of incidence. The PBS is operated at angles greater than the critical an- gle. The basic design principle is emphatically analyzed. The design of PBS is applied in projection sys- tem. The spectral wavelength region of the design is 420～680 nm,with the range of incident angle of ± 10°in air.The extinction ratios for the reflected and transmitted beams are over 1000..
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 406 (2005)
Application of genetic algorithm in the design optimization of grating profile
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Diffraction grating of high diffraction efficiency and low polarization dependent loss is a key component of the integrated wavelength division-multiplexing device and is of importance in optical communication. But it is difficult for traditional gratings to meet the special requirement of optical communication. A geneDiffraction grating of high diffraction efficiency and low polarization dependent loss is a key component of the integrated wavelength division-multiplexing device and is of importance in optical communication. But it is difficult for traditional gratings to meet the special requirement of optical communication. A genetic algorithm was used to optimize the profile of grating based on the theoretical calculation method of grating efficiency. A quadratic function was used to describe the grating profile, some original samples were selected, and diffraction efficiency of the sample gratings wascalculated by using the couple-wave approach. Furthermore a few transformations of coefficient of quadratic tuncnons were made by using different operators of genetic algorithm. The diffraction efficiencies of the gratings described by those transformed quadratic function were calculated, the grating profiles that were close to the special requirement were chosen, and others were rejected. Next the transformations of the new sample gratings were made again ,the diffraction efficiency of the gratings described by those transformed quadratic function were calculated again, and then above process was repeated, it was continued until the request was satisfied. By using the method mentioned before, finally we have achieved some optimizational grating profiles that have high diffraction efficiency and low polarization dependence loss. Diffraction efficiency of the gratings achieves more than 90 percent and polarization dependence loss is less than 0.1 dB. It meets the special requirement of optical communication. It is showed that genetic algorithm was used to optimize the profile of grating based on the theoretical calculation method of grating efficiency, it provides theoretical guidance for grating fabrication, and much manpower and material resource were saved..
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 410 (2005)
Analysis of sampled grating DBR semiconductor lasers using transfer matrix method
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Sampled grating DBR (SGDBR) lasers are the most promising one of the tunable lasers applied in optical communications.The spectral characteristics of sampled grating DBR semiconduct" or lasers was modeled using transfer matrix method.Gain region, phase region and sampled grating DBR are regarded as elementary partSampled grating DBR (SGDBR) lasers are the most promising one of the tunable lasers applied in optical communications.The spectral characteristics of sampled grating DBR semiconduct" or lasers was modeled using transfer matrix method.Gain region, phase region and sampled grating DBR are regarded as elementary parts in calculation.Every elementary part is regarded as a two"port device whose transmission property is expressed by a 2×2 complex matrix.Below threshold, emission spectra show different output characteristics under different injection currents into gain region and SGDBR.When the current injected in the active region is 9.5 mA,a main mode begins to arise near 1.553 μm. When there are currents in a sampled grating DBR, the positions at which main modesbegin to arise vary,which shows tunability.Meanwhile the current injected in the active region also varieswhen a main mode begins to arise.Threshold condition is also reflected using this method.Threshold currentis 10 mA..
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 415 (2005)
Pump uniformity study of solid state laser rods dircet side-pumped by laser diode
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The characteristics of the pumping light distribution in Nd：YAG rod direct side-pumped by diode bars are studied in this paper.Firstly, an approximation but simple analytical solution to the radical distribution of deposited energy in a diode-ba-pumped laser rod is provided based on the characteristics of the Gauss beaThe characteristics of the pumping light distribution in Nd：YAG rod direct side-pumped by diode bars are studied in this paper.Firstly, an approximation but simple analytical solution to the radical distribution of deposited energy in a diode-ba-pumped laser rod is provided based on the characteristics of the Gauss beam and the output of diode laser. Furthermore, the theoretical models of pumping energy distribution in a diode-array-pumped laser rod are made.Then, how the parameters （size of the medium, absorption coefficient of the medium, distance between the laser diodes, and so on） affect the homogeneity of pumping energy distribution in the medium is achieved according to the numerical simulation, and a set of general rules is summarized, and that can offer reference to experimental investigtion.The distribution of pumping light in Nd：YAG rod is measured with CCD camera which is in good agreement with computer numerical simulation. The experiment results are analyzed and discussed. The comparison results illustrate that the theoretical models are correct.Using ray trace algorithm, applying to the diffuse reflection surface medium and applying to multifarious direct side-pumping are the characteristics of the theoretical model..
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 421 (2005)
Target identifying of large visual angle to the laser fuse
[in Chinese], [in Chinese], and [in Chinese]
For the targets of limited size,the method of FPGA (field programmable gate array) based information system is proposed for target identifying.The coupling scan of transmission and four branch receiver are used to solve all aspect detecting, target is identified through four branch information. In the design, range couFor the targets of limited size,the method of FPGA (field programmable gate array) based information system is proposed for target identifying.The coupling scan of transmission and four branch receiver are used to solve all aspect detecting, target is identified through four branch information. In the design, range counter, orientation counter, dimension counter are realized. So the target is identified. Through simulating, experimental result shows the effectiveness.The method can automatically identify con- ditions of missile-target meeting, advance the anti-fog interference capability of laser fuse,and improve at- tacking efficiency. The method is adapted to the ai-to-air missile and anti-radialization missile..
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 427 (2005)
Light route research on optical fiber polarization characteristics test system
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Fibe-optic gyroscope is an interferometric sensor, and the characteristic of polarization influences its precision,therefore the polarization state of the fiber need to be tested.At the present,the system of polarization testing is soled abroad,but its index is low,and its price is very high.Accordingly,the testing sysFibe-optic gyroscope is an interferometric sensor, and the characteristic of polarization influences its precision,therefore the polarization state of the fiber need to be tested.At the present,the system of polarization testing is soled abroad,but its index is low,and its price is very high.Accordingly,the testing system used in home is made by ourselves,but its precision is not high universally.At the same time, the tested extinction ratio is smaller than its theoretic value.The design and tested result are given by some companies,yet the reason of the system＇s errors has not analyzed in detail. For this reason, in this article, based on the optical structure of high precision PM fiber polarization detection system,the optical errors that affect the extinction ratio are analyzed and calculated.After theoretically analyzing and calculating by computer simulation,in the range of given errors the extinction ratio can reach 55 dB,which fulfills the high precision measurement.And the transmission ratios of e rays and o rays are obtained by calculation. The transmission ratio of e rays is 2.34% higher than the past results..
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 430 (2005)
Experimental study on the dependence of DPB SFS' performance on pump power
[in Chinese], [in Chinese], and [in Chinese]
Erbium-doped superfluorescent fiber source technology is one of the key technologies of the high-precision fiber-optic gyroscope （FOG）.The performance of the source influences the FOG＇s scale factor and bias stability directly. Based on the optimum Erbium-doped fiber length has been fixed, the experimental investigatioErbium-doped superfluorescent fiber source technology is one of the key technologies of the high-precision fiber-optic gyroscope （FOG）.The performance of the source influences the FOG＇s scale factor and bias stability directly. Based on the optimum Erbium-doped fiber length has been fixed, the experimental investigation of the influence of pump power＇s fluctuation on DPB SFS＇s mean wavelength and linewidth were presented. Meanwhile the shifts of mean wavelength, linewidth and output power with temperature for several pump power were measured in this work by rapidly cycling the soure temperature between -20-60 ℃. The experimental results are as follows, when pump power in the range of 60-120 mW, the influence of pump power＇s fluctuation on DPB SFS＇s mean wavelength is -6.5 ppm/mW.Appropriate pump power can be selected in this range. Finally, the sample＇s mean wavelength stability reached 5 ppm（peak-to-peak）in 6 h,it can reach 2 ppm for short time （1 h）.The proper fiber Bragg grating to tailor the ASE spectrum are designed so that the width and shape of the spectrum can satisfy the high-precision FOG＇ s request..
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 434 (2005)
Optimization design of the length encoder of optical fiber delay lines
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
In the optical fiber delay directional detection laser warning system, the optical fiber delay lines are used to connect optical incept system with photoelectric conversion system,which plays roles of transmitting the laser,delaying the optical signals and encoding the optical signals simultaneously. Because the lengthIn the optical fiber delay directional detection laser warning system, the optical fiber delay lines are used to connect optical incept system with photoelectric conversion system,which plays roles of transmitting the laser,delaying the optical signals and encoding the optical signals simultaneously. Because the length of optical fiber delay lines is different, the laser pulse received by the optical windows will produce different time delay.Thus the transition of the laser azimuth information to the time information is realized.Because the length of optical fiber delay lines has direct effects on the volume of laser warning system, the optical loss ,the false alarm ratio and the optical fiber delay lines are permuted and combined based on the property of the laser pulse and the optimization theory. The optimal design ways of the length of optical fiber delay lines coding are brought forward,and the correlation theory is used for analysis and calculation. Arranging mode of full direction matrix is attained,and accordingly the relevant arranging principle is educed. According to the principal the permutation and combination are put up to the optical fiber delay lines.Accordingly the optimization of the total length of the optical fiber delay lines is obtained in theory, which provides the important theoretical argument for the optimization design of laser directional detection warning system..
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 438 (2005)
Radiation characteristics of suspend resistor
[in Chinese]
With the development of the technology of micromechanical processing, the Resistor Array becomes one of the most promising IR scene generators. In the Hardware-in-the-loop （HWIL） simulation system, it is usually used to test the real-time performance of IR camera, seeker and other IR detector systems. Resistor Array IRWith the development of the technology of micromechanical processing, the Resistor Array becomes one of the most promising IR scene generators. In the Hardware-in-the-loop （HWIL） simulation system, it is usually used to test the real-time performance of IR camera, seeker and other IR detector systems. Resistor Array IR scene generator adopts resistors as their microemitters. When current passes each resistor, it is heated and produces IR radiation. By adjusting the current of each resistor, the temperature of the resistor can be controlled, and then the IR scene is generated. Radiation characteristics （including IR emissivity of dielectric film, effective blackbody temperature, temperature resolution） of suspend resistor the basic celI of Resistor Array dynamic IR scene generator are introduced.Our analysess how that the suspend resistor has the characteristics of low power dissipation and high effective blackbody temperature, which can meet the simulation requirement of MWIR and LWlR radiation in hardwarein -the -loop simulation system..
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 442 (2005)
Thermal pulse video thermography nondestructive testing of the defects in carbon steel
[in Chinese], [in Chinese], and [in Chinese]
Carbon steel is widely used in many fields.It is of great importance to study the behavior of carbon steel in nondestructive testing.To investigate the behavior of carbon steel in thermal pulse video thermography nondestructive testing,two standard carbon steel test-pieces are made.The sizes and depths of defects in twCarbon steel is widely used in many fields.It is of great importance to study the behavior of carbon steel in nondestructive testing.To investigate the behavior of carbon steel in thermal pulse video thermography nondestructive testing,two standard carbon steel test-pieces are made.The sizes and depths of defects in two standard carbon steel test-pieces are studied by thermal pulse video thermography.The results show that for the purpose of minimizing errors of size measurements the testing time should be chosen at about 0.3 s after the thermal heat flux applied to the specimen with defects of smaller depths （l〈1.8 mm ） and it is more difficult to measure the size of shallower defect than that of deeper defects.For the defects with diameters larger than 6 ram,the depth measurement errors are usually small if the thermograms are in high contrast.If defect diameters are smaller than 6 mm, the depth measurement errors are usually more than 10% .To determine the depth of the defect it should be performed shortly after the thermal flux applied to the test-piece to avoid the blurring of the thermal images due to heat diffusion..
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 446 (2005)
Imaging guiding arithmetic evaluating system
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
This imaging guiding arithmetic evaluating system is used to evaluate the precision and stability of a guiding arithmetic on complex backgrounds, analyze the effects of sampling frequency, field of vision, template size,etc. It has the character of simply structure, lower cost and small volume. This system can either bThis imaging guiding arithmetic evaluating system is used to evaluate the precision and stability of a guiding arithmetic on complex backgrounds, analyze the effects of sampling frequency, field of vision, template size,etc. It has the character of simply structure, lower cost and small volume. This system can either be used in outfield testing or be used in infield experiment by using formerly accumulated data. Guiding arithmetic program compiled by user can be joined into this system, and then the performance of this guiding arithmetic can be tested easily. The hardware structure and software flow is briefly expounded in this paper..
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 450 (2005)
Fuzzy edge detection based on standard deviation gradient
[in Chinese], and [in Chinese]
Infrared image edge detection is one of the difficult problems in image processing.Based on the characteristics of infrared image,the minimum error thresholding algorithm is extended to the fuzzy domain and applied to the infrared image edge detection.The fuzzy edge detection algorithm for infrared image based on standInfrared image edge detection is one of the difficult problems in image processing.Based on the characteristics of infrared image,the minimum error thresholding algorithm is extended to the fuzzy domain and applied to the infrared image edge detection.The fuzzy edge detection algorithm for infrared image based on standard deviation is proposed.Firstly,a gradient operator based on local standard deviation is performed and potential edge regions are well separated.Secondly,a fuzzy minimum error thresholding algorithm is introduced to find a fuzzy thresholding of the gradient image,which partitions the gradient image into edge region and non-edge region.The experiment is conducted on various infrared images and the results show that the proposed approach has better performance than some classical edge detection methods based on gradient..
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 454 (2005)
Edge detection investigation of low-SNR infrared image based on noise probability
[in Chinese], [in Chinese], and [in Chinese]
Characteristics of IR images mostly include large noise, small distinction betweens target and background, blurry edge and so on. These characteristics make existent methods ineffective and require more effective method. Considering the random noise often accords with Gauss distribution, a statistic method based on noiCharacteristics of IR images mostly include large noise, small distinction betweens target and background, blurry edge and so on. These characteristics make existent methods ineffective and require more effective method. Considering the random noise often accords with Gauss distribution, a statistic method based on noise probability distribution and noise characteristics has been put forward to detect image edge. By analyzing the probability model of noise,it is proved that if the difference of neighboring dots is larger than a determinate value, the edge of infrared image can be detected in large probability. By comparing the infection of noise for statistic method and gradient method in different conditions, it is found that the noise restrain capacity of statistic method is higher than that of gradient method. Comparison and analysis are made between the statistic method and the often used Sobel algorithms. The analyses indicate that good results can be obtained when this statistic method is used to detect edge of infrared image and this method is simple and fast..
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 459 (2005)
New kind of clarity-evaluation-function of image
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The clarity-evaluation-function of out-of-focus blurred image is a key factor for auto-focusing by digital image processing and the accuracy and efficiency of the function need to be improved. It is found that the blurred image has large amount of pixels with low gradient while the focused image has obviously more pixeThe clarity-evaluation-function of out-of-focus blurred image is a key factor for auto-focusing by digital image processing and the accuracy and efficiency of the function need to be improved. It is found that the blurred image has large amount of pixels with low gradient while the focused image has obviously more pixels with high gradient than the blurred image after deep study of the gradients of various images. Therefore, we can threshold gradients in order to throw low gradients and remain high gradients. And then the advantages of focused image are obviously showed. A kind of clarity-evaluationfunction of out-of-focus blurred image is firstly proposed in the paper. It is the sum of Laplacian operator with threshold. The mathematical model is established individually, and the experimental results and analysis are also given. The clarity-evaluation-function of out-of-focus blurred image given here has the characteristics of non-deflection, single peak value, high sensitivity and SNR..
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 464 (2005)
Image ability to obtain correct matching based on feature matching
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The evaluating approach of image＇s ability to obtain correct matching based on image feature matching is discussed.It is suggested that information entropy and summation of image gradient can be used for evaluating image＇s ability to obtain correct matching.By the test of image matching based on comer feature and HausdThe evaluating approach of image＇s ability to obtain correct matching based on image feature matching is discussed.It is suggested that information entropy and summation of image gradient can be used for evaluating image＇s ability to obtain correct matching.By the test of image matching based on comer feature and Hausdorff distance, the relation among correct matching probability and information entropy and summation of image gradient is discovered.Strong correlation exists among correct matching probability and information entropy and summation of image gradient.It is shown that correct matching probability is increasing with the increasing of information entropy and summation of image gradient, although concrete rule is of tiny difference because of the field surface landscape＇s difference. Therefore, through calculating image＇s information content, automatic reference image selection and planning navigation route can be done.During real-time matching navigation, whether matching carded out or not would be confirmed by evaluation real-time image＇s information content.To do as such,higher correct matching probability would be obtained, misguide would be avoided and matching time would be saved. The method of the paper can also be available in image evaluation based on gray-level image matching..
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 469 (2005)
Applied method for small target registration
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The registration of multi-sensor images is a basic and key technique in image fusion processing,image fusion can be done effectively only after registration.Normal registration schemes are not suitable for small target because there are nearly no features can be used.Aiming to the characteristics of small target registThe registration of multi-sensor images is a basic and key technique in image fusion processing,image fusion can be done effectively only after registration.Normal registration schemes are not suitable for small target because there are nearly no features can be used.Aiming to the characteristics of small target registration,a new method of completed the registration by two steps is presented,and the idea of FOV registration is brought forward.Firstly,using imaging principle,with focus,resolution and pixel dimension of CCD,the FOV corresponding relation between different CCD is established,and then it is used to complete FOV registration by cutting and zooming out the FOV of target. Secondly,based on analyzing the disadvantage of the common used Minimum Absolute Deviation（MAD）matching,the method using Maximum Close Distance （MCD）matching to register target position is proposed.The experimental result shows that the method can register small target well,and the error is not beyond two pixels.Because it＇s strong pertinence,it can be used in project..
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 474 (2005)
Real-time image filtering method under smog interference
[in Chinese], [in Chinese], and [in Chinese]
On the basis of research on the application of image matching technique, the heavy-inter- ference image matching especially the real-time filtering technique suffered from the smog interference ef- fects is addressed.The smog interference makes the real-time image fuzzy,which causes the image matc- hing system unperforOn the basis of research on the application of image matching technique, the heavy-inter- ference image matching especially the real-time filtering technique suffered from the smog interference ef- fects is addressed.The smog interference makes the real-time image fuzzy,which causes the image matc- hing system unperform well or brings error-match worse. Firstly, the smog interferences′ effects on the image matching system especially on the real-time filtering is analyzed,also including the main parameters of the smog interference model and the fundamental design for filter realization. Then the related filter al- gorithm is proposed on the basis of the analyses above and the simulation filter is performed using Mat- lab.The results indicate that this algorithm can eliminate the smog noise sufficiently,and improve the quality of the real-time image under smog interference effectively,which also provide more design meth- ods for the technique of the real-time filter under the smog interference..
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 478 (2005)
Design and implementation of image matching system based on TMS320C6415
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Image matching machine is an important part of target recognition system. The scheme using TMS320C6415 as the core processor to realize an image matching system is put forward in this paper.SDRAM storing real-time pictures,preassembled and preset data,temporary data and program code, FLASH ROM solidified with code,preaImage matching machine is an important part of target recognition system. The scheme using TMS320C6415 as the core processor to realize an image matching system is put forward in this paper.SDRAM storing real-time pictures,preassembled and preset data,temporary data and program code, FLASH ROM solidified with code,preassembled and preset data, and dual port RAM realizing communication with superior control equipment are adopted in this project.Implementing image matching algorithm with software, image matching system with DSP is more flexible. TMS320C6415 is one of the most advanced DSPs in the world, and it has a processing ability of 5760 MIPS.Experiments show that this system is able to match two pictures of 512×512 within 0.02 s with PTT correlation algorithm or a picture of 72×72 and another picture of 320×320 within 0.1 s with product correlation algorithm. This system is featured by compact construction,high reliability,and good real-time ability.The system provides a new high-speed processing platform for an image matching system..
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 481 (2005)
Method of detecting small target in port-sea background
[in Chinese], and [in Chinese]
A new method is presented to detect small target in the port-sea background image.The image contains land and water area,and the target is in the water area, so the algorithm of automatic segmenting the area that we are interested in is presented.Firstly the land and water area are divided,then the black-white image whA new method is presented to detect small target in the port-sea background image.The image contains land and water area,and the target is in the water area, so the algorithm of automatic segmenting the area that we are interested in is presented.Firstly the land and water area are divided,then the black-white image which has been segmented is marked and the biggest block is distilled as the water area.Secondly the area＇s contour is scouted and it is filled with the original pixels. A local median median filter is executed to filter the rest bundance background elements.Eventually the real small target can be segmented by the F-R rule.And the experimental result shows that the method is effective.
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 486 (2005)
Spatial-temporal detection of dim point moving targets in IR images
[in Chinese], and [in Chinese]
After the discussion of detection performance and critical constraints of ideal spatial-temporal algorithm for detecting dim point moving targets in background-clutter suppressed IR images under the assumption of independent identical distribution of residual samples containing signal plus noise and nois ealone, a new After the discussion of detection performance and critical constraints of ideal spatial-temporal algorithm for detecting dim point moving targets in background-clutter suppressed IR images under the assumption of independent identical distribution of residual samples containing signal plus noise and nois ealone, a new practically efficient spatial -temporal detection algorithm is introduced in which there is no need knowing priori information about the noise or targets, instead they are estimated from the samples directly. The probabilistic distribution of statistic for binary hypothesis testing is derived and it＇s result is t-distribution function. The detection performance analysis, the problems remained in those two cases and their solutions are also given in this paper.The algorithm is useful for optically detecting meteors, satellites, and other moving targets which move in an arbitrary path across many frames of data..
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 490 (2005)
Analysis of the radius of microsphere particles based on Mie scattering theory
[in Chinese], [in Chinese], and [in Chinese]
To measure the radius of microsphere particles effectively, economically and accurately,the Mie scattering theory is adopted to design the radius measuring device.The theoretical analysis and numerical calculations of microsphere particle light scattering characteristics are carrying out by using Mie scattering theory.To measure the radius of microsphere particles effectively, economically and accurately,the Mie scattering theory is adopted to design the radius measuring device.The theoretical analysis and numerical calculations of microsphere particle light scattering characteristics are carrying out by using Mie scattering theory.Moreover, the relations of the distribution of scattering light and incident wavelength, the radius of microparticle and the relative index of the microsphere particle are presented. Three results are obtained.Firstly, the energy of scattering light distributes in the area where scattering angle is small when the incident wavelength is small.Secondly, the variety of the relative index has little effect on the distribution of scattering light.Thirdly, the distributions of scattering light have great difference according to different radiuses of microsphere particle,so that the radius of the microsphere particle could be obtained by measuring the distribution of the scattering light,therefore,the feasibility of the design scheme is proved theoretically.The radius measuring device for microsphere particles is designed based on theoretical analysis and numerical calculations.The device has the merits of simple structure,low cost and high efficiency.The device is practical and could be adapted to practical measurement..
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 495 (2005)
Design of the temperature controlling for UFPA thermal camera
[in Chinese], [in Chinese], and [in Chinese]
On the basis of analysis of the technical specifications of the 320x240 long wavelength infrared uncooled microbolometer detector developed by ULIS Corporation of France,the necessity of temperature controlling for microbolometer uncooled focal plane arrays thermal camera is discussed,and the essential aspect of designOn the basis of analysis of the technical specifications of the 320x240 long wavelength infrared uncooled microbolometer detector developed by ULIS Corporation of France,the necessity of temperature controlling for microbolometer uncooled focal plane arrays thermal camera is discussed,and the essential aspect of design of temperature controlling is presented.The merits of temperature controlling schematic by single chip microcomputer, liner mode monolithic thermoelectric cooler controller and switch mode monolithic thermoelectric cooler controller are discussed.A appropriate temperature controlling circuit for the 320×240 long wavelength infrared CMOS uncooled integrated microbolometer detector is developed by a single chip monolithic thermoelectric cooller controller, named ADN8830, produced by Analog Devices Inc.,and the temperature controlling circuit can keep the temperature change of the uncooled focal plane array detector in 30±0.01 ℃ so that the uncooled focal plane array detector work in the range of the most optimized temperature. This is a better scheme of temperature controlling for its high efficiency, low power and compact size..
Infrared and Laser Engineering
- Publication Date: Aug. 01, 2005
- Vol. 34, Issue 4, 499 (2005)
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