2014 Vol. 43, No. 5
2014, 43(5): 1359-1363.
The thermal expansion coefficient mismatch between InSb chips and silicon readout circuits was one of the prime reasons for cracking and indium column chip breakage, which carried out research InSb infrared Focal Plane Arrays (FPA) detectors banding on Si wafer. It used the technology of grinding, polishing thinning and the point cutting of diamond to cutting precisely on the backside of the chips, which on the purpose to have chips with a thickness of 15 m. The transmittance of infrared spectral obtained was higher than 88% in medium-short wavelength. The result shows that most of the important performance such as detectivity and responsivity of FPA under the bonding technique are equal to traditional structure FPA. Furthermore, the performance of these FPA doesn't degress after temperature shock experiment, which proves that the Si-bonding technology can solve the problem brought out by indium columns breakage of impact stresses, which plays a dominant role in the yield of InSb infrared focal plane arrays detectors.
2014, 43(5): 1364-1369.
The scene degradation and ghosting in scene-based nonuniformity correction methods for infrared focal plane arrays were analyzed here, and a novel approach based on Gaussian filtering with edge constraint was proposed for nonuniformity correction of infrared focal plane arrays. A Gaussian filter with edge constraint was designed to obtain the desired estimation of the image. The gain and offset correction factors in the iterative formula were calculated using the steepest descent method. Meantime, the convergence speed was increased through adaptive control of the iterative step. Both simulation and experiments on real infrared images demonstrate that this approach can remove the fixed pattern noise more effectively compared with the existing methods. It can effectively suppress the scene degradation and ghosting, retain the detailed image information, and improve the image quality.
2014, 43(5): 1370-1374.
High-frequency analog chain of 512256 staring short wavelength (SW) infrared-focal-planearrays( IRFPAs) readout-integrated circuit(ROIC), focusing on coupling of weak signal, high-frame output and noise depression was implemented in this paper. The complete analog signal chain contained a novel input stage of capacitor feedback transimpedance amplifier (CTIA) preamplifier, a correlated double sampling (CDS) module,an amplifier of charge and complementary output stage. The simulation and verification were carried out both before and after completing the layout. The circuit's structure was analyzed according to low-temperature model. The result shows that the output dynamic range is 2.8 V and the frame rate is above 250 Hz with output of 8 channels. The CTIA ROIC chip fabricated with CSMC-6S05DPTM 0.5 m process technology is measured and proved to be consistent with the simulation.
2014, 43(5): 1375-1379.
A new structure of dual side metal grating used to improve coupling efficiency was demonstrated. By using the three dimensional finite difference time domain algorithm, the proposed dual side metal grating for GaAs/AlGaAs Quantum Well Infrared Photodetector was studied. The optimization parameters at wavelength 4.8 m were confirmed by the electric field distribution and relative coupling efficiency at different periods, duty circles and metal thicknesses. The relative coupling efficiency of the proposed dual side metal grating was over three times of the counterparts of single side metal grating at front or back. The bimodal curve of the relative coupling efficiency for the dual side metal grating inspires possibility for potential application for two color Quantum Well Infrared Photodetector. The dual side metal grating can also be used to couple perpendicular incident light into one color, two color and multi color Quantum Well Infrared Photodetectors and offers a high coupling efficiency.
2014, 43(5): 1380-1384.
The application of infrared imaging seeker in weapons systems is becoming wider. In its development process, a dynamic infrared scene simulator test equipment is commonly used in laboratories, but there is still no measurement standard of dynamic infrared scene simulators, thus the accuracy and reliability of test results can not be guaranteed. A calibration device for dynamic infrared scene simulators was presented in this paper, which realized calibration for spectral range, frame rate characters, radiation temperature, non-uniformity and distortion of dynamic infrared scene simulator, and achieved good results.
2014, 43(5): 1385-1389.
Infrared technology for nondestructive testing under linear frequency modulated excitation is a new detect technology. The shortcomings of the traditional infrared NDT methods can be avoided and different detects can be defected by this method. In order to research the application of infrared technology for nondestructive testing under linear frequency modulated excitation, a two-dimensional heat conduction model was established by finite volume method. The temperature field of the model was obtained under linear frequency modulated excitation. The FFT algorithm was applied to the surface temperature of the model and then the phase was obtained. The influences of Chirp modulation time, heating intensity, material depth, height and width on the phase difference were respectively revealed. It is important for the application of infrared technology for nondestructive testing under linear frequency modulated excitation.
2014, 43(5): 1390-1395.
The hardware and software design of the dynamic radiation scanning thermometer was presented in this paper. The hardware part contained optical part and circuit part. The optical part was composed of optical scanning mirror, laser, lens and aperture stop. And the circuit included pre-amplifier circuit and data processing circuit. In the circuit part, the pre-amplifier circuit was composed of pre-amplifier AD820, inverting amplifier OP07 and relay components, while the data processing circuit was composed of STC12C5A16S2 microcontroller, MAX232 and 12864k12 LCD display. Besides, matrix keyboard was used which can set emissivity, scanning frequency and reset. AC/DC module was used as the power module. The thermometer was designed with high accuracy, fast response, easy testing and carrying and many other advantages. It can also be used in some serious conditions, such as high-risk, high-radiation, high corrosion. Thus, the market application prospect is very broad.
2014, 43(5): 1396-1400.
From the basic principle of infrared spectrum absorption method, the high-precision gas concentration signal processing calculation method of the IR optical sensor was presented. This paper focused on the establishment of the gas concentration calculation model and experimental method for determining the various parameters. From the analysis of the principle of gas concentration calculation method, a new formula for gas detection was obtained by gradually modifying the Lambert-Beer law. The formula can be used to calculate gas concentration. To reduce the environmental temperature influence on the detection results of infrared gas concentration, temperature compensation was required. Through temperature compensation, the sensor can be used in various temperature conditions. After measurement, the sensor has good stability and realizes the 10010-6 distinguishing ability. It meets most occasions use requirement.
2014, 43(5): 1401-1405.
Barium gallogermanate transparent glass ceramics were fabricated by crystallization processes, and their infrared and mechanical properties were studied in this paper. It was found that only ZrO2 crystal formed when barium gallogermanate mother glass was treated at 810-910℃ for 0.5 h. A few ZrO2 crystals with size of less than 10 nm appeared if mother glass was treated at 830℃. The average size of ZrO2 crystals separated was 250 nm when treatment temperature was up to 870℃. However, ZrO2 crystals would be large and congregated if treatment temperature was higher than 870℃. Barium gallogermanate transparent glass ceramics possessed excellent infrared and mechanical properties when mother glasses were treated at 810-850℃. When treatment temperature was up to 870℃, the mechanical properties of barium gallogermanate glass ceramics was better, but it was regretful that their infrared properties decrease. If treatment temperature increaseed, both infrared properties and mechanical properties of barium gallogermanate glass ceramics would decrease.
2014, 43(5): 1406-1410.
The accurate determination of spatially continuous temperature and pressure distribution on aerodynamic surfaces is critical for the understanding of complex flow mechanisms and for comparison with computational fluid dynamics predictions. Thermally sensitive phosphor coatings provide a way to obtain simple, inexpensive, full-field measurements of temperature with much higher spatial resolution. A new sort of two-color thermally sensitive phosphor coating was developed, which could be used to measure surface temperature between room temperature and 800 K. The various spectral regions in emission differ with temperature, which could be used to support the two-color temperature measurement method. The temperature calibration system was set up, and the intensity-ratio change curve as a function of temperature was obtained. The temperature distribution of curved surface was measured by two-color temperature measurement method. The results show that the two-color temperature measurement method has the ability of surface field temperature quantitative measurement.
2014, 43(5): 1411-1415.
In order to study the transmission properties of optical signal influenced by self-phase modulation (SPM) in semiconductor optical amplifier (SOA), based on the transmission equation, the generation principle of SPM was analyzed, the temporal and spectral characteristics of pulse transmitting through the SOA were obtained, the simulations are made separately to the pulse with no chirp and pulse with chirp. The result shows that SPM makes the shape of pulse decline and makes the spectrum broaden to lower frequency, and the degree of declination and broadening increases with growth of the gain of SOA, the sign of chirp coefficient determines whether the spectrum will be broadened to the high frequency or to the lower frequency.
2014, 43(5): 1416-1420.
Laser selective focusing structure has been introduced to enhance the response of the photodectectors remarkably. By using the amplitude Fresnel zone plate lens (FZPL) working in transmissive mode, high energy collection of laser light and high suppression of the other background light were obtained. A 36gain and a 4gain in responses were obtained for a mesa InGaAs/InP p-i-n photodetector and a planar InGaAs/InP avalanche photodetector(APD) integrated with FZPLs respectively, compared with the responses without FZPLs, when illuminated by the laser light. While illuminated by the Tungsten-halogen lamp, 30% deductions in responses were obtained with FZPLs compared with the responses without FZPLs. Strong enhancement of laser light absorption and obvious suppression of the light from the Tungsten-halogen lamp were obtained.
2014, 43(5): 1421-1427.
The theory and basic properties on the passive phasing in the ring-cavity structure was illustrated. The influence of the focal length on the mode-locking speed was analyzed. An analysis model was established consisting of a broad spectrum amplification model and a simplified model for stimulated Brillouin scattering effect. Speed and stability of the mode-locking in this scheme was shown to be determined by the variance of optical path difference, the dynamic phase noise and the stimulated Brillouin scattering effect. The simulation results show that, using a proper focal length, a fast mode-locking speed is obtained. The phase noise degenerates of the beam quality, and even causes the mode hoping. The stimulated Brillouin scattering effect of the fiber with high power output limits the peak power of each frequency, increases the peak number in the output spectrum, and causes degeneration of beam quality. The mechanism of the mode width decrease with the growth of feedback times is demonstrated in theory. The results show that the stimulated Brillouin scattering effect provides a mechanism of mode width growth, which makes the mode width maintain at a balanced value.
2014, 43(5): 1428-1432.
As a new type of laser source, supercontinuum has become a hot study, owing to its incandescent wide spectra and the brightness of the laser, but the reports of the beam quality are few recently. It inconveniences the application of SC. The method of measuring the beam quality of supercontinuum was put forward by analyzing and comparing the beam quality evaluation methods. The beam quality of a supercontinuum source was measured. The results shows that the beam quality of the supercontinuum source is closely related to the pump power density. The beam quality M2 factor is less than 1.5, when the pump power is small. The beam quality M2 factor is around 1.9, when the pump power is larger. In addition, the beam quality M2 factor of visible part is less than 1.5, and with the increase of the pump power, the beam quality of supercontinuum is getting better, the beam quality M2 factor is maintained at about 1.3.
2014, 43(5): 1433-1437.
The physical mechanisms of ultrasonic generation by laser pulse, the waveform characteristics of the generated laser ultrasonic signal and the influence of laser parameters on the ultrasonic signal were analysed theoretically. And two experimental apparatus were built that received laser ultrasonic with a piezoelectric ultrasonic transducer or an optical detection method based on two-wave mixing interference to verify the theoretical analysis results. In the experiment, the influence of the pulse laser parameters and the characteristic of the detected signals with two different detection method were analysed. Through theoretical analysis and experimental verification, the generated ultrasonic amplitude can be affected by the incoming laser parameters, and optical detection method based on two-wave mixing interference can detect complete laser ultrasonic waveform information.
2014, 43(5): 1438-1443.
The semiconductor lasers are widely used in various fields, this requires that their output power is increasingly improved, so the development of high power semiconductor laser with multichip-packaging is one of mainstream. A typical hundred-watt semiconductor laser packaged with 12 chips in ladder form was analyzed in thermal steady-state, obtaining the rule curves of the temperature of active region of chip and temperature rise by thermal coupling in different parameters of heat sink, and a heat sink structure with better heat dissipation was put forward.
2014, 43(5): 1444-1448.
Scattering of optical mirror surface makes a very important impact on properties of optical system. Laser transmission characteristics with different pollution conditions on optical mirror surface had been researched by using modified Mie theory and Bidirectional Reflectance Distribution Function(BRDF) of optical mirror surface, under three laser wavelengths of the visible light 0.632 8 m, near infrared light 1.053 m and thermal infrared light 10.6 m. The results show that if mirror surface roughness is much smaller than the incident wavelength ( ), scattering magnitude of clean mirror surface is proportional to and inversely proportional to . Scattering magnitude of particulate-contaminated mirror surface relates to size and quantities of particles on the mirror surface. The more complex particles distribute, the more significant scattering will be. In addition, when wavelength is shorter, BRDF will be greater, and scattering becomes very complicated.
2014, 43(5): 1449-1453.
For improving the quality of laser-induced acoustic signals, the laser-induced acoustic signal transducer was designed, its design theory and structure was analyzed and depicted. Experimental system was built. The pulsed laser was focused into water inside the transducer and in the free field respectively. A hydrophone was used to receive the acoustic signal and convert it into electric signals, a oscilloscope was connected with the hydrophone to display the signals. Laser-induced acoustic signals produced in two different environments have been compared. The results are as follows: compared with laser-induced acoustic signal produced in free field, that produced in the transducer has improved in its qualities. Peak pressures are 3 times larger. Signal energy is more concentrated below 60 kHz. Radiation angle has been decreased to 13.2in 1m distance. Signal attenuation gets slower.
2014, 43(5): 1454-1457.
The wide application of high power fiber laser makes it become a new hotspot in the research of solid state laser. But due to stimulated Raman scattering(SRS) and stimulated Brillouin scattering(SBS) effect, the maximum output power of single fiber is limited, and beam quality becomes worse with the increase of power variation. Method of parallel beam combining of fiber laser because of its poor beams, so that its application is restricted, and coherent beam combination technology can make multiple laser beam coherent superposition, so that the output power can be improved while ensuring good beam quality. In this paper, the design and theoretical calculation of one core, three core, seven core photonic crystal fiber light distribution were conducted, proving that integrated photonic crystal fiber can be very good to achieve coherent beam output, while achieving a high output power and high beam quality of fiber laser.
2014, 43(5): 1458-1462.
Gain modulation scannerless lidar is a new system of lidar. It is significant to investigate the range resolution of the lidar system. Based on the gain modulation lidar distance expression, the relationship between gain modulation lidar system parameters and range accuracy is being under investigation. Both photon noise with the weak echo intensity and gain saturation of the microchannel plate with the high range accuracy were taken into account. Curve between ranging accuracy and echo power was given. Gain modulation scannerless lidar system has a interval of echo power. By adjusting parameters to manipulate echo power into this interval, the highest ranging accuracy can be obtained.
2014, 43(5): 1463-1468.
Alkali vapor cell is one of the key components of chip-scale atomic clocks (CSACs), and its microfabrication is very significant yet challenging. Arrays of 87Rb vapor cell with dual-chamber for CSACs were batch fabricated by MEMS technology. Pure 87Rb vapor was produced by in-situ chemical reaction during anodic bonding process and buffer gas (N2) was backfilled to ensure the pressure is precisely controlled. The dual-chamber structure helps to prevent the impurity after reaction from blocking light path, in order to improve the intensity of optical signal. Optical absorption spectrum of 87Rb D1 line and the error signal used to lock the frequency of chip-scale atomic clock were finally obtained through experimental test. The peak-to-valley separation of the 87Rb D1 line error signal can reach 0.53 kHz at 90℃, which indicates that the 87Rb vapor cell can meet the requirement of CSACs or other chip-scale atomic devices (CSADs).
2014, 43(5): 1469-1472.
Chromium nanometer grating can be repetitively fabricated by atom lithography, this nanometer grating can be used as a nano pitch standard to realize the calibration of high precise measurement equipments, such as scanning probe microscopy, scanning electronic microscopy. In the high vacuum apparatus, chromium atoms evaporated from a high temperature effusion cell, and the propagating atoms interacted with the cooling light and standing light wave respectively, so they were collimated, focused and deposited on the InP substrate which located behind of the standing light wave. During 3h depositing, a nanometer grating with space distance of 212.78 nm, corresponding to the laser wave length, and height of 9 nm was obtained. Considering the low growing speed of nanometer lines, the possible reasons were analyzed and the solutions would be applied in the following experiments.
2014, 43(5): 1473-1476.
Micro devices of metal thin film may be directly processed by utilizing the UV laser at the wavelegth of 266 nm or 355 nm. However, due to the output power of UV laser is common lower at present, it is not suitable for directly processing the shine metal with the larger size and thick. In this experiment, in order to overcome the problems that shine metal possess the high reflectivity to the solid state laser of high power at 1064 nm and the fast heat dissipation, the resonant cavity and the scanning focusing system were optimized, then the laser single mode operation was realized and the power density was reached 1.592109W/cm2, which also make that the absorption of laser energy by atom changes into the absorption way by the plasma emission of the free electrons in the metal. Utlizing to the laser of average power of 50 W, repetition frequency of 500 Hz, spot diameter of 20 m, pulse duration of 80 ns, cutting velocity of 10 mm/s, the bigger copperplate with thick of 10 mm was directly processed accurately, the width and deepth of the groove by laser cutting were all 100 10 m, and the groove spacing was 30015 m, that were enough satisfied the initial target.
2014, 43(5): 1477-1483.
Optical properties of compact internal-mixed aerosol particles composed of black carbon coated with sulfate were carried out utilizing discrete dipole approximation (DDA) and Bruggeman effective medium theory for the size parameters from 0.1 to 25. The validity of effective medium theory(EMT) in the light scattering of compact internal mixture was performed based on the comparison of both methods. For the monodisperse particles, the EMT does an adequate job of simulating the extinction-, absorption-, scattering-, backscattering-efficiency factors, asymmetry parameters, extinction-to-backscatter ratios and single scattering albedos in Rayleigh scattering region with all the relative differences less than 7%.Nevertheless, the EMT does not do an adequate job in the range of Mie scattering except for the cases that the inclusions of the internal mixture are small enough with the volume percentage less than 1%. Usage of the EMT can mainly lead to significant underestimations of the scattering efficiency factors but overestimations of absorption efficiency factors and asymmetry parameters when the size parameters are more than 4. For the polydisperse particles, the EMT does an adequate job for the optical parameters with the relative differences less than 9%.
2014, 43(5): 1484-1489.
VPP retrieval algorithm shows good performance among the central region of micro scale wind filed. But on the edge, the wind field changes dramatically, destroys the continuity, and makes the retrieval method invalid. The method of identifying and locating the interference inversion region was studied. It was derived that horizontal tangential wind speed was the same at the same radial, thus the initial inversion results were corrected. An improved algorithm was put forward. The experiment was conducted using simulated doppler lidar data to prove the method, and it is proved to be effective.
2014, 43(5): 1490-1498.
Extended source light transmission through mean flow field and imaging have not been fully studied. When an extended source is closed to an imaging system in a forebody with a side-mounted window, light emitted by this extended source passing through the mean flow field and imaging are studied with ray tracing and Fourier optics. It is found that imaging deviation angles and imaging blur indexes of different point sources of the extended source are different. So integrated deviation index and integrated blur index are adopted to describe entire deviation and blur conditions of the extended source imaging, respectively. It is also found that when the relative position of the extended source and imaging system is invariant, and the mean flow field moves along flow, expansion and optical axis directions relative to the imaging system respectively, integrated deviation index and integrated blur index vary. Varying conditions of the two indexes are different among the three moving conditions. The reasons of these phenomena are deeply analyzed. In engineering design, this research may be beneficial to selection of a proper location of the imaging system relative to the window.
2014, 43(5): 1499-1504.
The concept of lobster optics was inspired by the unique structure of lobster eyes in biological world. The image points of the lobster eyes lens are distributed as a cross, which consist of focal arm and focal point. Due to the distribution of image points, there is significant background stray light in the lobster eyes lens, which seriously restricts its applications. Based on the analysis of the focusing process in the lobster eye lens, the absorbing coating method was proposed to suppress the stray light. Through combination of the end absorbing coating method and the penetration absorbing coating method, the cross focal arm and background stray light were obviously suppressed. With the model which is built with stray light analysis software, it is shown from the comparison that with absorbing coating method, the stray light of lobster-eyes lens can be remarkably inhibited. It is indicated that the level of background stray light is reduced by roughly one order of magnitude, the size of focal arms is decreased and its intensity falls by 40% under the premise of without reducing the illumination of central focus. It could greatly increase the SNR and the contrast of image.
2014, 43(5): 1505-1510.
In order to achieve the illumination of maskless lithography by rectangular collimated flat-top laser beam and improve the illumination efficiency, a design method of the illumination system using double freeform surfaces shaping unit was proposed. Based on the optical path constant condition and Snell's refraction law, the surfaces equations in integral form of the freeform surfaces were derived. The integral equations were solved by numerical calculation. The illumination systems using two-lens shaping unit and single-lens shaping unit which included double freeform surfaces were designed and simulated by optical design software. The simulated results show that the uniformity is over 93% and the illumination efficiency is over 91%. It is illustrated that the two kinds of shaping unit could meet the requirements of the illumination of maskless lithography.
2014, 43(5): 1511-1516.
Based on the characteristic of laser warning system with non-imaging imaging mode, a double cylindrical lens system was presented. A new optimization method, based on the ray tracing of cylindrical lens, was introduced in this paper. Traditional single-cylindrical lens and cylindrical reflector systems were limited by FOV, less than 1, and low-quality line spot. This optical system, composed by two ZnSe cylindrical lenses, meets the operating wavelength of 1.0-4.0 m and achieves a 20FOV and the modulation transfer function(MTF) is better than 0.7 at 7 lp/mm on the edge of FOV. This optical system achieves the requirement of laser warning system with non-imaging mode.
2014, 43(5): 1517-1521.
Deep brain stimulation (DBS) is effective for treating some diseases, such as epilepsy, Parkinson's disease or depression. DBS electrode is a key part of a DBS system. The current DBS electrode has four large contacts, and the stimulation resolution is low and the stimulation to unnecessary area of brain tissue may cause side effects. To improve the resolution and precision of the deep brain stimulation, a flexible electrode with multi-contact was designed and produced through a Micro-Electro-Mechanical Systems (MEMS) fabrication method. The new electrode consisted of 24 small contacts. Each electrode contact is 285 m 1500 m. The micro machining techniques were applied for the electrode fabrication using biocompatible materials Parylene C as the substrate and Au as electrode material respectively. The characteristics of the electrode were physically tested. The electrode has a smooth surface, distinct outline and good electrical properties with low impedance. The MEMS technology is suitable for the deep brain stimulation electrode production. This research would provide a basis for developing better 3-D deep brain stimulation strategy.
2014, 43(5): 1522-1528.
A method was developed based on the diffractive micro-optics theory for design and fabrication of diffractive micro-optics elements employed in infrared wavelength range. Several elements were fabricated by standard semiconductor technological process. Infrared diffractive elements were mainly used to form complex light fields, and both of the intensity or amplitude and the phase of light out from the elements mentioned above, can be processed efficiently. Above all, the diffractive micro-optics elements produced by the introduced method can transfer common Gaussian beams into desired images which have been affected by atmospheric turbulence through creating fine patterns over the surface of the elements, and the structures can be used to generate turbulence wavefront for simulating the light field in atmospheric turbulence, and then represent wavefront for evaluating the influence of atmospheric turbulence.
2014, 43(5): 1529-1534.
Different from the light distribution characteristics of the traditional light source, LED light characteristics are more complex, the second optical design for LED used in automotive lighting needs to be done. According to the light distribution characteristics of LED automobile headlamp, a freeform optical lens design method for LED headlamp was presented in this paper. By establishing one-to-one relationship between the coordinates of point on the receiving surface and the coordinates of point on the freeform surface of lens according to energy conservation principle, determining the mapping relationship between the energy and the lens, and applying the illumination optimization method, the coordinates of point on the freeform surface of lens was solved out with numerical methods based on non-imaging optics theory, then modeling software was used to establish an optical model for the freeform optical lens. Through tracing the light with Monte Carlo simulation method, the final effect of light distribution fully meets the Automotive headlamps with LED light sources and/or LED modules (GB25991-2010) standards. The simulation results show that the optical efficiency is improved greatly and can be up to 91%.
2014, 43(5): 1535-1539.
Zoom cam is a pivotal part used for driving every lens group in zoom lens,the design result of cam curve is decisive importance for motion property and system precision as well as system imaging in zoom system, therefore, zoom cam design is an important part of the zoom lens design, a fine cam performance is the basic requirements to reach lens design of image quality goal and optical zoom process. In order to design a excellent curve form to ensure the pressure angle was smaller, make the process stability and movement smooth fluent, reduce the zoom systems driving moment, and ensure a stability zoom imaging, in the cam design process, we constructed functions which were driving moments of variable group and compensation group with their own pressure angle. Then, combination goal optimization function was built, optimal values of variable group curve pressure angle and compensation group curve pressure angle were optimized and calculated. Optimization results show that the cam drive moment significantly reduces, and improve the overall performance of zoom cam is improved.
2014, 43(5): 1540-1544.
Image scanning system is the core sub-system of aerial camera. It requires high scanning accuracy, high scanning frequency, small size, simple structure, otherwise, the image is blur and image frame rate is low. Low-precision scanning mechanism abroad changes the rotary motion into linear scanning movement using rotary motor plus cams, gears, worm and other mechanical transmission mechanism. The image plane scanning system is bulky, has complex structure and low intelligence. It does not match the trends of future camera. Voice coil motor is chosen to produce linear reciprocating motion for the new design high-frequency and high-speed image scanning structure. Image scanning mode was rectangular scanning. In order to achieve high control accuracy and high repetition rate, intelligent control method with continuous force control of VCM was introduced. Image scanning frequency can reach 15 Hz, scanning speed accuracy can be in 0.2%, the linear travel was at least 0.2 mm, linear scanning speed is 103 mm/s. The experimental results shows that it is stronger in robustness, better in adaptability, the quality and effect of control are satisfactory. This result can meet the specific requirements of the project.
2014, 43(5): 1545-1548.
Based on the theory of optical passive athermalization and the research of athermalization for dual-field-view un-cooled LWIR optical system, a LWIR optical system with large relative aperture and 3x step zoom was designed using chalcogenide glasses which posses good thermal stability and unique LWIR optical properties. The specifications are as follows: F/# is 1, EFL is 50/150 mm, and total length is 240 mm. The 640480 FPA detector was adopted whose pixel size is 17 m17 m with working band from 8 to 12 m. Three LWIR material was used in the system which were Ge, ZnS, IRG201. The image quality is diffraction limited from-40 to 60℃at both WFOV and NFOV.
2014, 43(5): 1549-1554.
For monitoring the work states of optical remote sensor in real time and automatically alarming when the work states are abnormal, the power characteristic analysis method based on command sets of optical remote sensor was developed. By sampling and iterating the relationship between power and various command sets, the dynamic threshold function based on command sets was summarized. And the threshold function was optimized, since some actual conditions must be considered such as surge, command delay and so on. And the optimized threshold function was applied to the power monitor and control system. The system adopted 20 Hz sample frequency to monitor the power of optical remote sensor in the heat cycle experiment, which would last 12.5 days. The command refresh cycle was 512 ms of the optical remote sensor. The results show the method can exactly monitor states of optical sensor and alarm when the states are abnormal. That puts power alarm method of optical remote sensor into practice and has great value to tester.
2014, 43(5): 1555-1560.
When spacecraft moves in the orbit using FOG navigation system, the performance of inertia instrument will fall off after experiencing a long and complicated environment. The power of light source falls off is a kind of fault mode. This mode will induce FOG's bandwidth to decline and the navigation precision will descend when spacecraft transfers to the other orbit or moves to a bigger angle. To resolve this problem, a method to compensate FOG's bandwidth using particle swarm optimization algorithm was brought forward. With this method a dynamic compensator could be realized without knowing the dynamic characteristics of FOG. The parameter of the compensator was optimized according to the measurement data of FOG and the reference model. But sometimes this method ran into local optimization easily. To increase this algorithm's performance, simulated annealing algorithm was induced to avoid local optimization. Finally, dynamic navigation experiment of FOG navigation system show that this algorithm is effective. This method can increase navigation precision when spacecraft moves to a bigger angle and possess a better engineering value.
2014, 43(5): 1561-1567.
Star maps are the indispensable and important data in the research on star sensors. It is a short cut to perform star map simulation utilizing computers. A method was presented to simulate the procedure of optical system imaging for star sensors to obtain star maps by extension programming. A system to simulate star maps was established. Firstly, the necessity of extension programming to realize imaging simulation by taking advantage of the extension interference was discussed on the basis of analyzing the basic principle of simulating optical system imaging for star sensors. Then, the methods to simulate imaging, add false stars and noises to maps, store and output star maps were introduced. Complete applications of extension programming were also introduced. Finally, the design result of the system to simulate star maps was given out. Examples were also presented as for the given optical system. The simulation method was validated. It is proved that the simulation method is correct, and can be handled easily and simply. Programming workload is less. The simulation system has advantages of fine interface, versatile, and has the ability to offer rich and multiplex data. It is significant to promote the study of star sensor technologies.
2014, 43(5): 1568-1573.
Importance of ultraviolet calibration is growing fast as ultraviolet payloads are wildly used in national space plan. Calibration device for UV radiation celestial body simulator was established especially for the calibration of instantaneous radiation parameters and high-sensitivity radiation parameters. Parameters such as spectral radiance, spectral irradiance can be calibrated from 200 nm to 400 nm. The calibration device is perspective for its application in national system.
2014, 43(5): 1574-1581.
In order to improve isolation degree of disturbance, a new active disturbance -rejection controller based on disturbance frequency adaptive was proposed. Firstly, the ESO based on disturbance frequency adaptive was designed in order to avoid phase lag when ESO observed the disturbance in the second-order and more second-order system. And then, the controller was designed. Finally, an experiment was performed to test the disturbance rejection performance of the ADRC based on disturbance frequency adaptive when the speed disturbance was from 0.1 Hz to 2.5 Hz as compared with the traditional square lag-lead compensation method. The results show that ADRC can reduce the disturbance error 6.72 dB at least. And the isolation degree of disturbance was improved obviously when the perturbation frequency was more than 0.5 Hz, the best isolation degree of disturbance was increased 12.94 dB. And the ADRC had strong robustness, allowing system parameters to range from-10% to 10%. In conclusion, the ADRC based on disturbance frequency adaptive satisfies the performance requirements of aerial photoelectrical stabilized platform and has higher practical value.
2014, 43(5): 1582-1586.
Holographic three-dimensional deformation test has important significance in the military, industrial test, however its applications are limited because of the requirements of traditional holographic recording, development, fixing, reconstruction and home position. In this paper, applying the charge-coupled device(CCD) digital holography was realized. It avoided not only the developing, fixing processes of traditional hologram recording material, but also the shortcoming of nonlinear recording of holographic material. Based on double exposure holographic interferometry and four-step phase shift method principle the digital phase shift was achieved, replaced the traditional mechanical phase shift method with piezoelectric translator, and the 3D deformation of an object was tested. From the 2D contour map and 3D plot of object deformation, the size, shape, and deformation direction of the deformed object could be interpreted. A lot of experiment results show that these method can not only simplify the optical layout of holographic interference testing, but also easy operate and increase measure precision. The precision can be up to 1/10 wavelength.
2014, 43(5): 1587-1593.
In order to accurately estimate the line-of-sight (LOS) angular rate of the strapdown seeker, strapdown seeker mathematical model was established, decoupling and estimation algorithm of LOS angular rate was based on the movement of the missile and target relative relationship. Firstly, a mathematical model of the strapdown seeker was established, and the Taylor series was used for its linearization. Secondly, according to the movement of the missile and target geometry and coordinate system relative relationship, the LOS angular rate decoupling algorithm was derived. Strapdown seeker can not directly measure the body line-of-sight (BLOS) angular rate, differential coefficient+steady-state Kalman filter was proposed to estimate the BLOS angular rate. Finally, LOS angular rate decoupling and estimation algorithm verification system was established and simulation experiment was carried out. The results showed that, the absolute error of decoupling algorithm was less than 510-5 rad/s and relative error was less than 0.3%, the correctness of the decoupling algorithm was verified. Under the conditions of containing seeker mathematical model, the steady-state Kalman filter was used by the angular frequency of 19.2 rad/s, LOS angular rate estimation error was less than 410-3 rad/s, nearly an order of magnitude was improved than direct differentiation method estimation error. The decoupling and estimation algorithm of the LOS angular rate can at the same time meet the requirements of the guidance system accuracy and dynamic performance.
2014, 43(5): 1594-1599.
The full envelope robust control of flying wing UAV is a difficult point because of its wide envelope and non-conventional layout. In this paper, a flight control scheme was proposed based on adaptation cascade active-disturbance-rejecdon control (ADRC) technique. The robust control design was divided into two steps; Firstly, a nonlinear mathematical model for the algorithm of flying wing UAV was deduced. Secondly, the flying wing UAV inner and outer ADRC attitude controller were designed respectively, the extended state observer was used to estimate and implement dynamic feedback compensation, and then the NLSEF was used to inhibit the compensating residual; ADRC controller was designed without a precise model of vehicle, and without precise perturbation boundaries of aerodynamic parameters. The simulation shows that the control structure is robust from low altitude and low speed to high altitude and high speed. The control system can overcome the impact of large-scale perturbations of interference and aerodynamic parameter.
2014, 43(5): 1600-1604.
An (ABBA)44-type one-dimensional photonic crystal was made from magnetic single -negative material A and electric single-negative materials B. Numerical calculation results indicate that there are three Tamm states in the range of 4500-7 500 nm with following characteristics. When the incident angle increases, the transmittance of Tamm states remain the same, but their location blue shifts. The shift rate of TE wave's Tamm states is larger than TM wave's at same incident angle. When geometric thickness of two media increases at the same time, the transmittance and the full-width half-maximum of Tamm states of TE and TM wave remain the same, but their location red shifts. When permittivity of A medium A increases, the transmittance of Tamm states of TE and TM wave remain the same, but their location red shifts, and their full-width half-maximum will be narrowed and then widened.
2014, 43(5): 1605-1609.
The way that adjustable light interference the imaging process of the TV seeker is to confront TV guidance weapons. Based on introducing the process of camera obtaining images, the relationship between the image grayscale and illumination condition, camera parameters was theoretically analyzed firstly. Then the influence on gain control with different light intensity ratio and irradiating area ratio was discussed, and the adjustment curve of gain with the light conditions changing was got. Finally, the experiment about how global illumination and partial illumination influent on image quality and how the illumination in accordance with certain control time order influent the imaging process of CCD camera was carried on, and the quality of interference image by using the function of structural similarity(SSIM) was evaluated. The results show that this way of interference is very efficient. The adjustable light can interfere the imaging process of CCD camera, and can make image quality reduced greatly.
2014, 43(5): 1610-1615.
In order to satisfy the high precision demand of photoelectric tracking system, a servo system was designed for a novel fast-steering mirror in detail. Firstly, the mathematic model of fast-steering mirror was established. A method of combination of velocity closed loop and position closed loop was adopted for the servo system of fast-steering mirror, and the parameters of the position compensation and the velocity compensation were designed. Secondly, the servo system was realized based on DSP. And the constitution of the servo system was expatiated clearly. Thirdly, the two working modes and the software working process of the servo system of fast-steering system were all described. Finally, the fixing point experiment and the tracking experiment were finished to verify the performance of the servo system of fast-steering system. Experimental results indicate that the response of the fast-steering servo system is very fast, the stable error of which is less than 0.3in the fixing point experiment. And the mean square root of the tracking error of the fast-steering servo system is less than 7in the tracking experiment. The servo system for the novel fast-steering mirror can satisfy the system requirements of high precision and fast response for the photoelectric tracking system.
2014, 43(5): 1616-1620.
Grating pair is the most important component of increment encoder, its structure and diffraction effcet are directly related to detection precision. The paper deeply analysed that the characteristics of diffraction single-grating and double-grating, and from the angle of spatial modulation deduce relation, grating pair influence Moire fringe. It analyzed the window function of the grating pair from both macro and micro perspectives, the uncertain reasons of the Moire fringe optoelectric signal waveform and contrast, and then proved that single-grating angle detecting can not only decrease frequency ingredient of output signal but achieve higher division precision and contrast. In order to prove the feasibility of single-grating angle detecting, this paper finally given a complete single-grating angle detecting way.
2014, 43(5): 1621-1626.
In situ Ni3Al and NiAl intermetallic compound composite laser cladding coatings were prepared on H13 hot die steel surface by controlling Al content in the Ni-based self-fluxing alloy powder. The chemical composition and phase structure of the different laser cladding composite coatings were characterized by optical microscopy (OM) and X-ray diffraction (XRD). The results indicate that the four kinds of composite laser cladding coatings all show a smooth, dense and without obvious defects macroscopic morphology. The dendrite region becomes wider and the dendrite size gradually becomes thicker in the laser cladding coatings bottom with the increase of Al content, even a columnar crystal phenomenon can be found. Without Al, the main phase of the composite coating is Ni3Fe and Ni-Cr solid solution. While with the increase of Al content, the main phase changes from Ni3Al intermetallic compound and Ni-Cr solid solution to Ni3Al+NiAl intermetallic compound and Fe-Cr solid solution, and then to NiAl intermetallic compound and Fe-Cr solid, when the Al content increases to 13.9%. At the same time, the impurity phase in laser cladding coating decreases with the increase of the Al content. The cladding coatings friction coefficients are lower than those of the H13 steel substrate. The highest microhardness of the coating increases by 250% and the abrasion resistance increases by 480% respectively.
2014, 43(5): 1627-1629.
ZnMoO4:Ce4+ blue phosphors were synthesized by high temperature solid-state method. The phase formation and luminescence properties of ZnMoO4:Ce4+ were analyzed by XRD, PL and CIE. The results show that ZnMoO4:Ce4+ blue phosphors have been successfully prepared by high temperature solid state method according to theoretic ratio, and the synthesized ZnMoO4:Ce4+ has a triclinic structure with pure phase. The phosphors have strong electron absorbability of 395 nm and can emit blue light with high intensity. The CIE of ZnMoO4:Ce4+ blue phosphor is (0.14,0.09). In addition, when the concentration of Ce is 3 mol%, the luminescent intensity of ZnMoO4:Ce4+ is highest.
2014, 43(5): 1630-1636.
In this article, we proposed an optical fiber sensing system for measuring vibration, strain and temperature based on the multimode interference of single-mode-multimode-single-mode (SMS) fiber structure, because the output optical power of the SMS fiber structure changed with the external environment parameters, such as vibration (frequency and amplitude), strain and temperature. From the variation of the output optical power, the strain on the multimode fiber could be obtained. The frequency and amplitude of the vibration and temperature of the SMS fiber structure could be obtained when FFT or Hilbert transformation was employed. With the calibration of the system, some cases of vibration and temperature change were measured with the error of less than 0.7 Hz and 5.0%, respectively. The SMS optical fiber sensing system can be used for multi-parameter measurements with extremely simple structure and low cost.
2014, 43(5): 1637-1642.
The attenuation of light signal in circulating interferometric optical gyro increases with the increase of cycling loops due to the use of coupler. In this paper, an improved design method of circulating interferometric optical gyro was proposed by using directional coupling modulator to replace the ordinary coupler. The cross state and direct state in the directional coupler could be obtained by adjusting the working voltage. The coupling mode could be controlled to be different when the light pulse signal went into the cycling light path or the light cycles out of the coupler. The light signal amplitude in the cycling light path could then be improved, and the attenuation caused by coupler was reduced. Simulation results show that the proposed method can increase the detected light intensity and improve the signal to noise ratio, which will improve the measuring precision effectively.
2014, 43(5): 1643-1647.
An estimation algorithm based on Kalman filer was developed to remove noise of the fiber temperature sensing system and to estimate the state in real time. The fiber temperature sensing system was the linear and dynamical system. Temperature was the time-discrete state variable which was modeled by Gauss-Markov random process with the additive and white Gaussian state noise. Based on Bayesian-MAP inference and MMSE criterion, the posterior state can be estimated by update equations with new measure. Given the initial parameters, the optimal estimator of temperature was achieved by such iterative process. FGC-LR, the distributed optical fiber Raman temperature sensing system, was the experimental setup with 2 km sensing fiber. The interval between adjacent sample points was 1 m. Local variance and SNR were used to evaluate the algorithm's performance in noise removal and estimation. The local variance is reduced by 83.56% at low temperature point and 84.09% at high temperature point. SNR at the normal temperature point (at 1 000 thm) and the heated points (at 1850 thm) are increased 18.45% and 16.80% respectively. These mean that the algorithm works well in noise removal of fiber sensing signal both at room-temperature and at heated points.
2014, 43(5): 1648-1653.
The error of commercial fiber optic current transducer (FOCT) must be less than 0.2%, the signal processing is a key factor for high-accuracy current sensing. The topology, operational principle, technical advantage, signal characteristics of fiber optic current transducer was introduced. A new scheme based on digital open-loop detection for the measurement system of the FOCT was presented, the working principles and features of this design were analyzed. The experimental results show that the FOCT's measurement precision is improved by using the improved measurement system, and the FOCT can satisfy the accuracy requirements of the 0.2 class measuring electronic transducer, meeting the requirements of digital substation, so it is valuable for solving a great deal of problems, such as the signal processing, measurement accuracy, measurement sensitivity, et al.
2014, 43(5): 1654-1659.
The complementary nature of low-level light image intensifiers and thermal infrared cameras makes them possible to observe the scene under almost any conditions (day/night/smoke/fog). A color fusion method of low-level-light and infrared images was introduced to render multiband imagery in comparative realistic color appearance. Firstly, the center-surround opponent-color fusion scheme was used to yield color imagery. Next, the histograms of the image were matched to those of the reference image in YCbCr color space. This transfered the natural color characteristics of daylight imagery into multispectral night vision images. In order to enhance the contrast of the fused imagery, a grayscale fused image was used to replace the luminance component of the multiband imagery and then implement the histogram matching. The experiment results demonstrate the proposed method is effective in displaying the fused imagery in natural colors and popping out targets. This fused data can help observers or machine vision systems to process this type of images efficiently, therefore reducing detection and recognition times and improving situational awareness.
2014, 43(5): 1660-1666.
An effective, four-stage fire-detection algorithm used to automatically detect fire in video images was presented in this paper. An adaptive Gaussian mixture model was used to detect moving regions in a video clip. A fuzzy C-means (FCM) algorithm was adopted to segment the candidate fire regions (fire and fire-colored objects) from these moving regions based on the color of fire. Some special parameters were extracted based on the tempo-spatial characteristics of fire regions; these parameters included the area randomness, surface roughness and motion estimation of fire. Finally, these parameters extracted from the third stage were used as input feature vectors to train a support vector machine(SVM) classifier, which was then used by the fire alarm to distinguish between fire and non-fire. Experimental results indicate that the proposed method outperforms other fire detection algorithms, providing high reliability and a low false alarm rate.
2014, 43(5): 1667-1671.
The distillation of near-infrared star image of star tracker was analyzed in this paper. A new method for this problem was presented. Firstly, characters of near-infrared star image in wavelet domain were analyzed and mask used to detect stars in multi scales were designed according to the distribution of the gray of stars. Then, local threshold was applied to overcome the imbalance of the background under the constant false alarm rate. Lastly, positions of the heaviest gray values of stars in the secondly decomposed approximation coefficients were accessed, eliminating the effect of the single point noise and stripe noise. Experimental results indicate that the method could efficiently obtain the position of the heaviest gray value of detected stars with error around one pixel, which satisfies the requirement of estimation of centroid.
2014, 43(5): 1672-1678.
In the process of non-uniformity correction for the infrared images using the interframe registration based least-mean-square-error non-uniformity correction algorithm (IRLMS), the accurate estimation for the displacement of the moving foreground was lacked in the scenes where moving foreground exists and the the rate of calibration parameter can not be adaptively updated in control when the registration accuracy is low, thus ghosting would be produced. To solve this problem, an improved interframe registration based least-mean-square-error non-uniformity correction algorithm was presented in this paper. LK optical flow was used to re-registrate the moving foreground, estimating the motion displacement and correcting the error image, to overcome the ghosting caused by the moving foreground. Meanwhile, the peak of the phase correlation matrix of the images which has eliminated the non-uinformity can be estimated, and the peak can be used to correct the updating rate of parameters adaptively, to overcome the impact causing by the overquick updating rate of the calibration parameter. As is shown in the experimental results, this method can suppress the ghosting phenomenon in the case that the foreground is moving and the registration accuracy is low, and improve the practicability of the IRLMS algorithm effectively.
2014, 43(5): 1679-1684.
In order to reduce the blocking artifacts resulted from Ttetrolet transform algorithm, Tetrolet transform was improved and Cycle Spinning was employed to avoid the blocking artifacts in this paper. And thus the improved Tetrolet transform was introduced and performed for image denoising. Some numerical experiments show the effectiveness and superiority of our technique. Compared with typical Tetrolet transform, the denoised images by our method are smoother, and the blocking artifacts is improved to some extent and inhibition. At the same time it can preserve more significant information of original images, such as local features, including image edges and image details. In addition, the proposed method gives better performance in Peak Signal to Noise Ratio (PSNR) and improves the quality of subjective and objective of image. Experimental results show that the proposed algorithm is effective and feasible, and can perform better on most data sets.
2014, 43(5): 1685-1689.
Localization of body surface features is needed for the correctness of localizing acupuncture points that determines the acupuncture effect. In this paper, a novel optical method was presented for locating surface features. Firstly, the images around the human model were collected using a camera on a designed optical platform; Then, the images were processed using Gabor filter into magnitude response, and the local maximum were obtained; Finally, the contour features localizing anatomical landmarks were extracted. To test the feasibility and accuracy of the proposed method, the features in gray and binary images were respectively extracted using the edge detection operators (Sobel, Canny, LoG and Gabor operator). It is found that, the contour features by Gabor filter are continuous and clearest; and the filtering effects of the binary images are better than that of the gray. The results show that the proposed method is valid for locating accurately and quickly the surface contour features, and it lays a foundation for further extracting anatomical landmark based on contour features and studying the optical method localizing the acupoints.
2014, 43(5): 1690-1696.
In order to solve the quality problem of remote sensing image degradation which is caused by fuzzy and noise in the process of push-broom full-color TDICCD space camera acquisition, transmission, and storage image, a new remote sensing image restoration method based on modulation transfer function (MTF) was proposed. The method in this paper restored point-spread function PSF by MTF, and took it as degradation model for image restoration. The ability of noise resisting of MTF extraction was raised in this paper via enhancing the local image by homomorphic filter algorithm before MTF extraction. Then by using the two times restoration method, MTF error which is caused by adding enhancement filter directly was avoided. Finally, the effect of remote sensing image restoration was evaluated by mean, contrast and edge strength. In experiments, the recovered image grayscale average increases 45%, average gradient is 3.5 times and the edge strength is 1.75 times greater than the values before restoration. And the area which is contained by MTF curves increases. The experimental results show that all above evaluation indexes are better than the original image. In conclusion, the image restoration algorithm of space TDICCD camera has certain reference significance in improving image quality.
