Journals >Optics and Precision Engineering
Contents
2011
Volume: 19 Issue 1
27 Article(s)
Export citation format
Research Article
Temperature characteristic of in-fiber Mach-Zehnder interferometer using twin-core fiber
FAN Lin-yong, JIANG Wei-wei, ZHAO Rui-feng, PEI Li, and JIAN Shui-sheng
A Mach-Zehnder interferometer using a Twin-core Fiber(TCF) was researched for temperature sensing and a comb-filter based on the in-fiber Mach-Zehnder Interferometer (MZI) was fabricated by splicing a section of single mode TCF between two single mode fibers (SMFs). The Free Spectral Range(FSR) of the transmission specA Mach-Zehnder interferometer using a Twin-core Fiber(TCF) was researched for temperature sensing and a comb-filter based on the in-fiber Mach-Zehnder Interferometer (MZI) was fabricated by splicing a section of single mode TCF between two single mode fibers (SMFs). The Free Spectral Range(FSR) of the transmission spectrum for the device versa the wavelength, the length of TCF and the effective index difference between the two cores were analyzed and the temperature characteristic of the device was experimentally tested.The tested results indicate that the transmission spectrum of the device has a red shift and a quadratic curve with the temperature increasing. Under the same temperature difference, the wavelength shifts are different at different wavelengths and the wavelength shift at short wavelength is smaller than that at longer wavelength. The sensitivity of the device is different at different wavelengths, and it is proportional to the temperature at a fixed wavelength. Furthermore,the insertion loss of the device is decreased effectively by tapering the splicing regions between SMFs and TCF.Finally a device with insertion loss about 7 dB was implemented. This device is relatively small, simple, compatible and suitable for fiber optic temperature sensors..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 19, Issue 1, 1 (2011)
Removal function for fabrication of WolterⅠgrazing mirror by elastic ball tool
WANG Yong-gang, CUI Tian-gang, MA Wen-sheng, CHEN Bin, and CHEN Bo
A novel technology for fabricating WolterⅠgrazing mirrors by an elastic ball tool was described in this paper. According to the Hertz contacting theory and Preston equation, a removal function model for tool movement on a cylinder surface was established based on the precession motion. The comparison of the theoretica1A novel technology for fabricating WolterⅠgrazing mirrors by an elastic ball tool was described in this paper. According to the Hertz contacting theory and Preston equation, a removal function model for tool movement on a cylinder surface was established based on the precession motion. The comparison of the theoretica1 model and the experimental results shows that the RMS distance warp between the theoretica1 removal function curve and the experimental curve is 0.101 22 μm，and its deflection ratio is 9.8%. Furthermore, the effect of different precession angles on the removal function was validated,which points out that the larger the precession angle is, the more the material are removed and the max removal point moves to the centre of contact area closely. With different precession angles, the rms deviation of max removal depth is 0.201 μm and the rms position deviation of max removal depth is 0.255 mm. The experimental results verify the feasibility of the theoretica1 model of removel function.The model can direct the fabrication of WolterⅠgrazing mirrors and can realize the deterministic material removal..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 19, Issue 1, 10 (2011)
Measurement of thickness of metal thin film by using chromatic confocal spectral technology
MA Xiao-jun, GAO Dang-zhong, YANG Meng-sheng, ZHAO Xue-sen... and TANG Yong-jian|Show fewer author(s)
To precisely measure the thickness and thickness distribution of a self-supporting metal film, the measurement technology based on a chromatic confocal spectral sensor was established. The measurement principle and system structure were descripted in detail, and the measurement uncertainty was analyzed. The thickness aTo precisely measure the thickness and thickness distribution of a self-supporting metal film, the measurement technology based on a chromatic confocal spectral sensor was established. The measurement principle and system structure were descripted in detail, and the measurement uncertainty was analyzed. The thickness and thickness distribution of the self-supporting metal film with the thickness between 10-100 μm were tested using the sensor group, precise displacement platform and precise calibrated samples. The measurement uncertainty was evaluated based on analysis of sensor accuracy, the uncertainty of calibration sample thickness, the positioning accuracy of two sensors and the system repetition uncertainty. Experimental results indicate that the measurement uncertainty is about 0.12 μm,which satisfies the requirements of Inertial Confinement Fusion(ICF) for target parameter measurement in high stabilization, high precision and non-destruction..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 19, Issue 1, 17 (2011)
Self-mixing velocimetry based on verical-cavity surface-emitting laser
L Liang, ZHANG Ke, DAI Ji-jun, ZHU Jun... and YU Ben-li|Show fewer author(s)
The self-mixing interference based on a Vertical-cavity Surface-Emitting Laser(VCSEL) was investigated. By taking a VCSEL as the source of a self-mixing interferometric system, the effect of different types of scattering surfaces and injection currents on the self-mixing signals was analyzed. It is concluded that the bThe self-mixing interference based on a Vertical-cavity Surface-Emitting Laser(VCSEL) was investigated. By taking a VCSEL as the source of a self-mixing interferometric system, the effect of different types of scattering surfaces and injection currents on the self-mixing signals was analyzed. It is concluded that the black and glossy photographic paper target will bring unfavorable influence on the self-mixing velocimeter and the operating currents with 1-1.4 times of the threshold currents can offer a self-mixing signal with a stable and great amplitude. For the longer preheating time, the power-up time of self-mixing velocimeter was discussed, and the results show that Doppler frequency will be stable and accurate after 17 s. The obtained results provide instructions for the parameter optimization and the choice of light source of a self-mixing velocimeter using the VCSEL..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 19, Issue 1, 23 (2011)
Design of beam shaping unit for deep ultraviolet lithographic illumination system
ZHAO Yang, and GONG Yan
To manufacture the integrated circuit chips at 90 nm or below their nodes by using a 193 nm exposed wavelength deep ultraviolet lithography, a beam shaping unit for the lithographic illumination system was designed to achieve the annular illumination and the continuous adjustment of a partial coherent factor σ to meet To manufacture the integrated circuit chips at 90 nm or below their nodes by using a 193 nm exposed wavelength deep ultraviolet lithography, a beam shaping unit for the lithographic illumination system was designed to achieve the annular illumination and the continuous adjustment of a partial coherent factor σ to meet the requirements of different exposed line widths. Firstly, the function relationships between the moving distance of axicon and the light beam magnification were deduced by using the laws of geometric optics and trigonometric functions, and the ranges of parameters of axicon were determined after analyzing the feasibility of zoom cam and the tolerance sensitivities. Then, the axicon and zoom lens were combined to implement the beam shaping unit. Finally, a kind of reducing scale zoom lens was designed to add into the combined system to achieve the continuously adjustment of the σ. The result shows that the normalized annular width Δσ and the outer diameter of annulus σouter can be adjusted continuously in the range of ［0.25, 1］ and ［0.4, 1］, respectively , which meets the needs of design..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 19, Issue 1, 29 (2011)
Assessment of storage reliability for FOGs by multivariate degradation data
CHAO Dai-hong, MA Jing, and CHEN Shu-ying
Storage reliability of Fiber Optical Gyroscopes(FOGs) was studied based on a multivariate degradation data method. Firstly, the dependence of multivariate performance degradation data was analyzed by means of the covariance matrix and the failture probability of products was characterized by a joint probability densityStorage reliability of Fiber Optical Gyroscopes(FOGs) was studied based on a multivariate degradation data method. Firstly, the dependence of multivariate performance degradation data was analyzed by means of the covariance matrix and the failture probability of products was characterized by a joint probability density function. From that, an universal method to evaluate product reliability via multivariate degradation data was achieved. Based on the characteristics of FOGs, the bias, bias stability and factor change were selected as degradation parameters, and a related storage test was carried out to obtain the performance degradation data. The storage reliability of FOGs was assessed by multivariate degradation data. Obtained results show that, in ambient environment of 60 ℃, the storage life is about 32 800 h and 13 200 h as considering the dependence and independence of FOGs’ multivariate degradation data,respectively.These data demonstrate that the reliability evaluating method from multivariate degradation data is more reasonable,and it can be extended to other product assessments with multivariate degradation parameters..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 19, Issue 1, 35 (2011)
Superior application of LED to street lighting
JIN Peng, YU Chun-yu, ZHOU Qi-feng, WANG Yi-feng, and WU Na
To compare the luminous efficiencies of different street lightings, it is necessary to establish an appropriate photometric measuring model.In this paper, two kinds of traditional street lights and two kinds of Lighting Emitting Diode(LED) sources were selected for comparing their luminous efficiencies in the mesopic sTo compare the luminous efficiencies of different street lightings, it is necessary to establish an appropriate photometric measuring model.In this paper, two kinds of traditional street lights and two kinds of Lighting Emitting Diode(LED) sources were selected for comparing their luminous efficiencies in the mesopic state and photopic state, then the MOVE model was used to derive the luminous efficiencies of the four kinds of lightings. Compared with the luminous efficiencies in photopic state, the luminous efficiency of the LED street lights and the Metal Halide(MH) lamps have improved significantly in the mesopic vision. However, the efficiency of the Hight Pressure Sodium(HPS) has decreased under the mesopic vision. Furthermore,when background luminance varies from 0.03 cd/m2 to 0.1 cd/m2, and then to 0.3 cd/m2,the luminous efficiency of the LED street lighting in the mesopic visual state will decrease from 131.2 lm/W to 122.7 lm/W firstly but then increase to 140.5 lm/W. It is concluded that the sensitivity of human eye changes in the different brightnesses of backgrounds. Among HPS, MH, standard LED light and modified LED light based on mesopic vision theory,the LED can offer the best solution in energy saving. Moreover,the LED lightings with more high efficiency can be obtained further by optimizing their spectra..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 19, Issue 1, 51 (2011)
Off-axis parabolic/Lloyd mirror interferometric systems for manufacturing plane holographic gratings
Bayanheshig, SHAO Xian-xiu, CUI Ji-cheng, LI Wen-hao, and QI Xiang-dong
The design and manufacturing of interferometric exposure systems with high wave-front flatness and structural stability is a paramount condition for development of high-quality holographic diffraction gratings. A ray-tracing was carried out on straightness of the interference fringes arisen from four kinds of interferoThe design and manufacturing of interferometric exposure systems with high wave-front flatness and structural stability is a paramount condition for development of high-quality holographic diffraction gratings. A ray-tracing was carried out on straightness of the interference fringes arisen from four kinds of interferometric exposure systems of Single Reflective Mirrors (SLR),namely, off-axis parabolic/Lloyd mirror system, single lens/Lloyd mirror system, spherical mirror/Lloyd mirror system and the separation of pairs of lens/Lloyd mirror system. A standard grating was placed in the interferometric field to make two parallel light beams for exposure incident on the grating, so that the diffractive light was superpositioned to appear Moire fringes.Then, the Moire fringes metioned above were simulated.The Zernike polynomial was used to fit the Moire fringes to get wavefront aberration of interferometric exposure systems and to compare the differrences among the four systems. The results show that the off-axis parabolic/Lloyd mirror system is the most appropriate in production of small-caliber plane holographic gratings. On that basis, the off-axis parabolic/Lloyd mirror interferometric exposure system was manufactured to fabricate plane holographic gratings with a maximum size of 110 mm×110 mm and the engraved linear density greater than 1200 l/mm.The diffraction grating wave-front aberration produced by the plane holographic grating is 0.239 6λ (λ = 550 nm) ,as the mirror face accuracy aberration between off-axis parabolic mirror and Lloyd mirror is λ / 8 (λ = 632.8 nm).This system can be used to produce plane holographic gratings with wave-front aberration in λ/6-λ/7(λ=550 nm), if the external disturbance is overcome and finely tuned..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 19, Issue 1, 56 (2011)
Error correction of satellite orbit predicted by vehicle-borne tracking and position device
ZHANG Pei-lu, GUO Li-hong, WANG Jian-jun, and YU Guo-quan
When a vehicle-borne tracking and position device is used to track a Low Earth Orbit(LEO) satellite,the obtained prediction data of the satellite orbit by the traditional satellite tracking software usually show a lower prediction accuracy. Meanwhile, the target is missed easily because of the cloud or zenith blind zonWhen a vehicle-borne tracking and position device is used to track a Low Earth Orbit(LEO) satellite,the obtained prediction data of the satellite orbit by the traditional satellite tracking software usually show a lower prediction accuracy. Meanwhile, the target is missed easily because of the cloud or zenith blind zones during the target tracking. To improve the satellite orbit prediction, this paper presents a new method which uses the improved Laplace method to predict satellite orbits based on the measured data by the vehicle-borne tracking and position device. In consideration of the prediction errors come from the prediction model, measuring axis and the coordinate transfer, it proposes an interpolation method to correct the error between predicted value and actual measured value and to obtain a higher accuracy direction value. The testing data show the accuracy of predicted data has increased from 3′ to 10″ in azimuth and elevation when the data are extrapolated to 7 s, which realizes the stable satellite tracking in the cloud or zenith blind zones..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 19, Issue 1, 64 (2011)
Thermal design of electric cabinet for high-resolution space camera
CHEN Li-heng, and XU Shu-yan
A thermal control system of electric cabinet in a high-resolution space camera was designed to resolve its heat dissipation. The basic flow sheet of thermal design for the electric cabinet was introduced,and several kinds of approaches in thermal conductions and thermal radiation were used to dissipate the heat for theA thermal control system of electric cabinet in a high-resolution space camera was designed to resolve its heat dissipation. The basic flow sheet of thermal design for the electric cabinet was introduced,and several kinds of approaches in thermal conductions and thermal radiation were used to dissipate the heat for the electronic components, Printed Circuit Boards (PCBs) and their chassises.Then, the finite element mode of thermal analysis was corrected according to the thermal test in the vacuum condition.Based on the results of thermal test and thermal analysis, the thermal design was modified by adding a heat pipe additionally. Finally,according to the space environment and structure characteristics, the thermal analysis for the thermal control system was performed by the corrected mode and the case temperatures of the electronic components were calculated. The results show that the case temperatures of electronic components are from 40.2 ℃ to 62.7 ℃ after adding the heat pipe, which means the thermal design scheme is feasible and reasonable for the electric cabinets of space cameras..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 19, Issue 1, 69 (2011)
Statics analysis and structure parameter design of robot shoulder joint based on orthogonal mechanism
CUI Bing-yan, and JIN Zhen-lin
In order to increase the workspace and carrying capacity of a robot shoulder joint and to improve its popularity and adaptability, a novel robot shoulder joint was proposed based on 3-RRR orthogonal spherical parallel mechanism. The statics performance of the robot shoulder joint was analyzed and the structure parameteIn order to increase the workspace and carrying capacity of a robot shoulder joint and to improve its popularity and adaptability, a novel robot shoulder joint was proposed based on 3-RRR orthogonal spherical parallel mechanism. The statics performance of the robot shoulder joint was analyzed and the structure parameters were designed. Firstly, the static transmission equation of the robot shoulder joint was established based on the principle of virtual works.Then,by use of the norm in matrix theory, the force Jacobian matrix was introduced into the statics performance evaluation index to define the statics performance evaluation index and the global torque performance evaluation index and to plot the performance atlas of the statics performance evaluation index at the work spaces of the robot shoulder joint. Furthermore, the objective optimal function based on the global torque performance evaluation index of the robot shoulder joint was established, and the relation of the objective optimal function and the global torque performance evaluation index was analyzed. By use of fully automatic searching method, the optimal structural parameter ranges of the robot shoulder joint are 49.8-60 mm for the middle follower length of WB and 90-112 mm for the frame connecting rod length of AU. Analysis results show that the robot shoulder joint has good static transmission performance at the initial position, and the static transmission performance decreases with increasing turning angle. Finally, using a set of optimal structural size parameters, a novel robot shoulder joint was designed..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 19, Issue 1, 77 (2011)
Vibration damping design for airborne electro-optical surveillance platform
WANG Ping, WANG Wei, DING Jin-wei, CHENG Zhi-feng, and LIU Jia-yan
In order to reduce the influence of vibration on the image quality and precision stability of a airborne electro-optical surveillance platform,a vibration damping design was performed. Based on the detailed analysis of complex damping theory,a two-grade damping system between the inter and outer frames of the platform In order to reduce the influence of vibration on the image quality and precision stability of a airborne electro-optical surveillance platform,a vibration damping design was performed. Based on the detailed analysis of complex damping theory,a two-grade damping system between the inter and outer frames of the platform was designed to isolate the vibration from inter frame to outer frame effectively in view of the shortcoming of the single-stage vibration isolation system. By using the two-dimensional parameter optimization method, the optimum natural frequency ratio fopt and the optimum damping ratio ζopt of the vibration damping system were calculated to be 1.43 and 0.243,respectively. Finally, the vibration damping effect was illustrated through a vibration test. Compared with the previous single-stage vibration isolation system, experimental results show that the maximum vibration transmissibility of vibration damping system is lower by 50%, the frequency range of vibration transmission rate less than 1 is wider, and the amplitude range of transmissibility on high frequency is much better than that of the single-stage vibration isolation system. It is concluded that the vibration damping design is feasible and effective for electro-optical surveillance platforms..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 19, Issue 1, 83 (2011)
Influence of built-up edge phases on characteristics of surface profile of micro cutting
LIU Zhi-bing, and WANG Xi-bin
The influences of Built-up Edge(BUE) phases of a rake face on the characteristics of surface profile of micro cutting were researched, which provided the proof for the optimal selection of cutting parameters and the evaluation for the characteristics of surface profile of micro cutting. The surface profile data in micrThe influences of Built-up Edge(BUE) phases of a rake face on the characteristics of surface profile of micro cutting were researched, which provided the proof for the optimal selection of cutting parameters and the evaluation for the characteristics of surface profile of micro cutting. The surface profile data in micro cutting were measured with a profilometer in different BUE phases, BUE free, BUE formation, BUE stable and BUE drop. The influences of the BUEs on the characteristics of machined surface profiles were analyzed with mathematical statistical functions such as Amplitude Density Function(ADF), Auto-correlation Function(ACF) and Power Spectral Density Function(PSD), as well as the time series model parameters and Auto Regression(AR) spectra. Obtained results indicate that in BUE free and BUE stable phases, the AR spectral peaks of micro cutting surface locate at 91.7 c/mm and 93.7 c/mm, respectively, which are very close to the reciprocal of a feed rate; while in BUE formation and BUE drop phases, the spatial frequency is significantly low compared with the reciprocal of feed rate. It is concluded that the consistency of the surface profile is deteriorated by the irregular contact between BUE and chip,and the low spatial frequency component becomes more dominant in the AR spectra of machined surface profile during BUE formation and BUE drop phases..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 19, Issue 1, 90 (2011)
Digital microfluidic chip by electrostatic manipulation in low voltage
LIU Xiang, GAO Hua-min, LI Tie, ZHOU Ping, and WANG Yue-lin
A digital microfluidic chip by electrostatic manipulation was designed and fabricated for a micro total analysis system. The principle of the electrostatic manipulation was proposed and the fabrication processes and experimental platform were demonstrated. For the chip,the silicon was taken as a substrate,a silicon oxiA digital microfluidic chip by electrostatic manipulation was designed and fabricated for a micro total analysis system. The principle of the electrostatic manipulation was proposed and the fabrication processes and experimental platform were demonstrated. For the chip,the silicon was taken as a substrate,a silicon oxide film as the insulating layer,a TiW/Au film as the electrode array, a Si3N4 film as the dielectric layer, and the fluorocarbon polymer as the hydrophobic layer. With an open structure instead of complex sandwich structure, the chip just needed a coplanar controlling electrode with one layer, so the process was simplified greatly. As the electrode array was embeded in the SiO2,the electric leakage from poor step coverage and dielectric breakdown at the margin were prevented.Furthermore, with thin dielectric layer and fine hydrophobic layer, the manipulating voltage was reduced greatly. Experiments show that,by controlling the sequence of voltage to the electrode array, the droplet can be transported smoothly in the two-dimension planes with a programmable manner at a low voltage of 20 V, and the maximum speed has reached 96 mm/s. The digital microfluidic chip can be used in a Lab-on-chip due to its simple structure and IC compatible fabrication processes..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 19, Issue 1, 97 (2011)
Combined hot-film anemometers for measuring flow speed vectors
QUE Rui-yi, ZHU Rong, LIU Peng, and ZHOU Zhao-ying
To realize the measurement of the air flow vector on a Micro Air Vehicle(MAV), a new type of hot-film anemometer which was lighter than a pitot and firmer than a hot-wire anemometer was developed and a corresponding combined system was also presented. Similar to the hot-wire anemometer, the hot-film anemometer is sensiTo realize the measurement of the air flow vector on a Micro Air Vehicle(MAV), a new type of hot-film anemometer which was lighter than a pitot and firmer than a hot-wire anemometer was developed and a corresponding combined system was also presented. Similar to the hot-wire anemometer, the hot-film anemometer is sensitive to both magnitude and direction of flow speed,and its output is a resistance when either the flow magnitude or direction changes.Moreover, by combining the sensor array simply, the flow speed vector could be acquired in a angle range, and thus its application area was expanded. Based on the experimental tests on the sensor characteristics, the principles and conditions of the combination scheme were researched,the method to arrange the sensor array was given and the speed vector measuring error was discussed. The experimental results indicate that arranging 3 hot-film anemometers with a separation angle of 45° to form a combination system can measure the flow vector in the angle range of 180°. Both of theoretical and experimental results prove that the presented combination method is effective and feasible,and its volume and energy consume are both lower than those of traditionnl methods. It can be further expanded to other flow sensors with similar characters..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 19, Issue 1, 103 (2011)
Design of symmetrical microwave power sensor
WANG De-bo, and LIAO Xiao-ping
In order to overcome the measurement errors of traditional microwave power sensors due to mismatch and thermal losses, a symmetrical microwave power sensor based on the Micro-electro-mechanical System(MEMS) was proposed and its microwave loss, temperature distribution and the accurate measurement were researched. FirstIn order to overcome the measurement errors of traditional microwave power sensors due to mismatch and thermal losses, a symmetrical microwave power sensor based on the Micro-electro-mechanical System(MEMS) was proposed and its microwave loss, temperature distribution and the accurate measurement were researched. Firstly, expressions of the loss power and loss voltage were derived according to the proposed loss model, and the heat transfer analytical model of the power sensor was established. Then, the sensor was designed and fabricated. Finally, the compensation factor, sensitivity and the frequency-dependent characteristics of the power sensor were measured and analyzed. The measurement results show that the compensation factor of the power sensor at 5, 10 and 15 GHz are 1.56, 2.12 and 2.56 dBm, respectively. The sensitivity is about 0.18 mV/mW, and the relative difference of the output voltage with the microwave frequency is below 2%. It is concluded that the symmetrical microwave power sensor can measure the microwave power by measuring the DC power, and also can improve the measurement accuracy of the microwave power significantly..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 19, Issue 1, 110 (2011)
Carbon nanotube sensors based on 555 multivibrators
ZHAO Zhen-gang, LIU Xiao-wei, WANG Xin, JIN Hai-yan, and TAN Xiao-yun
The capacitive signals of capacitive carbon nanotube humidity sensors are usually tested by measuring instruments, which restricts the uses and developments of the sensors seriously. Focusing on this problem，one kind of capacitive carbon nanotube humidity sensor based on a 555 multivibrator was presented. Firstly, the The capacitive signals of capacitive carbon nanotube humidity sensors are usually tested by measuring instruments, which restricts the uses and developments of the sensors seriously. Focusing on this problem，one kind of capacitive carbon nanotube humidity sensor based on a 555 multivibrator was presented. Firstly, the principle of the sensor and the detecting circuit were discussed, and the sensor was designed and fabricated. Then, the sensor was tested by both the RCL apparatus and the proposed circuit, respectively. Finally, the response and recovery time of the sensor was tested. The testing results demonstrate that when the Relative Humidities (RH) surrounding the sensor change from 11% to 97%, the capacitive sensitivity and the output frequency sensitivity of the sensor are 905% and 889%,respectively. The frequency sensitivity is closed to the capacitive sensitivity, which means the circuit can well change capacitive signals to frequency signals.Furthermore, the adesorption and desorption time of the sensor is about 4 s and 18 s, respectively,which shows the sensor can offer low power consumption and fast response and has potential application prospects..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 19, Issue 1, 118 (2011)
Al doped poly-Si micro-heater for thermomechanical fabrication of micro/nano structure
RONG Hao, ZHAO Gang, and CHU Jia-ru
For thermomechanical fabrication of the micro/nano structure, a micro-heater made of Al doped poly-Si was fabricated. The Al doped poly-Si film was prepared by annealing from Al/a-Si∶H compound film under 750 K for 18 h on a Si3N4 substrate using Aluminium Induced Crystallization (AIC) process, and the characteristics For thermomechanical fabrication of the micro/nano structure, a micro-heater made of Al doped poly-Si was fabricated. The Al doped poly-Si film was prepared by annealing from Al/a-Si∶H compound film under 750 K for 18 h on a Si3N4 substrate using Aluminium Induced Crystallization (AIC) process, and the characteristics of the transformation caused by annealing were analyzed by Raman scattering spectroscopy, scanning electron microscopy and a resistivity meter. It was shown that the boundary between an Al layer and an a-Si∶H layer disappears after annealing,and a uniform film is formed. After annealing，the Raman spectral peak shifts from 478 cm-1 to 520 cm-1,which means the film surface changes from the a-Si∶H to the highly-crystallized poly-Si. Meanwhile, the resistivity of the film declined is from over 1010Ω·cm to 16.8×10-3 Ω·cm at 300 K for doping of Al atoms. The results indicate that the bilayer film (Al/a-Si∶H) has been changed into a uniform Al doped highly-crystallized ploy-Si film. Furthermore,the integration of the Al doped poly-Si micro-heater and Si3N4 cantilever was also discussed. Simulated by ANSYS, the micro-heater is heated to 782.8 K under a periodic electrical pulse with a voltage of 10 V and duration of 0.3 μs. When the pulse disappears, its temperature cools down to 420 K within 1 μs. The simulation results show that the Al doped poly-Si micro-heater has good thermoelectric properties, and it is well suitable for the thermomechanical micro/nano structure fabrication..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 19, Issue 1, 124 (2011)
Nonlinear ultrasonic test of micro-nano crack
DUN Yi, SHI Xiao-hong, WANG Guang-long, and ZHOU Zhao-ying
A self-built nonlinear ultrasonic test system was established and the interaction between ultrasonic waves and cracks in metal materials and the distortion effects of ultrasonic waves were researched to implement the ultrasonic test of micro-nano cracks in metal materials. On the basis of the presumption that nonlinearA self-built nonlinear ultrasonic test system was established and the interaction between ultrasonic waves and cracks in metal materials and the distortion effects of ultrasonic waves were researched to implement the ultrasonic test of micro-nano cracks in metal materials. On the basis of the presumption that nonlinearity of ultrasonic waves in solid materials is universal, the distortion effect caused by the interaction between ultrasonic waves and the micro-nano cracks in metal materials was explored. Then, according to the analysis on the distortion effect, the measurement of ultrasonic high-order harmonic amplitude was illustrated. Finally,a regular ultrasonic test and a nonlinear ultrasonic test were conducted respectively on fatigue cracks in metal materials, which proves that the nonlinear ultrasonic test is more effective for the micro-nano crack detection. Experiments show that the length of a fatigue crack is relative closely to the exciting efficiency of the second harmonics and the length of the crack detected by the nonlinear ultrasonic method based on the second harmonics is 30% longer than that by the regular ultrasonic test, which realizes the test for micro-nano cracks in metal materials..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 19, Issue 1, 132 (2011)
Structural analysis of ground-based large telescopes
ZHOU Chao, YANG Hong-bo, WU Xiao-xia, and ZHANG Jing-xu
To research the performance of ground-based large telescopes and to optimize the design and structures of telescopes,the finite element analysis for the whole assembly was performed. For a 1.23 m telescope,the structural characteristics of main parts and their relation were studied,several kinds of simplification methoTo research the performance of ground-based large telescopes and to optimize the design and structures of telescopes,the finite element analysis for the whole assembly was performed. For a 1.23 m telescope,the structural characteristics of main parts and their relation were studied,several kinds of simplification methods for some parts were discussed and a precise finite element model of the whole telescope assembly was established. Moreover,the gravity deformations of the telescope in both zenith and horizon pointing states were calculated and the deformation results of the primary mirror and the secondary mirror were given. Finally,the telescope assembly dynamic responses due to the wind loading and seismic excitation were analyzed. The obtained results show that wind loading will induce the optical axis misalignment of the primary mirror and secondary mirror, and the misalignment error RMS value is allowable in 0.025″. The displacements along three orthogonal directions induced by seismic excitation are greater, but the maximum stress is only 16.67 MPa, which cannot bring the damage to telescope structures..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 19, Issue 1, 138 (2011)
Online estimation for scale factor of north-finder based on rate biased ring laser gyroscope
ZHANG Yan, WU Wen-qi, and Wu Mei-ping
To satisfy the engineering requirement of high precision north-finding, the north-finder based on a Rate Biased Ring Laser Gyroscope (RBRLG) and its measurement error come from the scale factor of RBRLG were studied to solve the problem on the scale factor slow change resulted from the inner temperature change and the To satisfy the engineering requirement of high precision north-finding, the north-finder based on a Rate Biased Ring Laser Gyroscope (RBRLG) and its measurement error come from the scale factor of RBRLG were studied to solve the problem on the scale factor slow change resulted from the inner temperature change and the instability of lock-in region of the RBRLG. Firstly, the change rule of scale factor was researched by a scale factor test. Then, the influence of the scale factor change on the north-finding precision was analyzed by a simulation. Finally, an online first order recursive algorithm was established to estimate the scale factor change according to the periodicity of RBRLG measurement. By introducing the platform angle measurement, the scale factor changes could be obtained. Simulated results indicate that the estimation error for the scale factor of RBRLG is less than 1×10-6 by the proposed algorithm, and the standard deviations of north-finding results caused by the scale factor change decrease to about 2″.The experiment on the north-finder results shows that this algorithm can effectively restrain the north-finding error caused by scale factor change,and the standard deviation is about 24″ for 5 min, which can basically satisfy the requirement of high precision north-finding..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 19, Issue 1, 146 (2011)
Acoustic emission real-time detecting instruments for metal cracks in machining exact details
ZHENG Geng-feng, MA Shun-feng, and JIN Long-xu
To improve the reliability and security of maching exact details in space equipment and to shorten their developing periods,a real-time detecting method for the metal cracks in machining exact details was presented. According to this method, a prototype machine of real-time detecting instrument for the cracks of exact To improve the reliability and security of maching exact details in space equipment and to shorten their developing periods,a real-time detecting method for the metal cracks in machining exact details was presented. According to this method, a prototype machine of real-time detecting instrument for the cracks of exact details based on a float digital signal processor—TMS320F28335 was developed. In consideration of online real-time detecting, the Acoustic Emission(AE) technique was adopted in the method. The general scheme for detecting metal cracks in real time was introduced and the hardware composition and software algorithm corresponding to the system were analyzed in detail. Finally, the verification experiments to the prototype machine of real-time detecting instrument were carried out. The experimental results show that the prototype machine has high performance. Its false detecting ratio reaches 1.2% and has no missing cracks,which validates that the AE real-time detec-ting method for the crack detecting is efficiency..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 19, Issue 1, 153 (2011)
Distortion correction for images in planar metrology
SU Cheng-zhi, WANG En-guo, HAO Jiang-tao, CAO Guo-hua, and XU Hong-ji
In consideration of the effect of the distortion error of an image on the accuracy of planar geometrical measurement in the precise visual metrology,a method to correct the image distortion by using standard grid board directly as measurement calibration is proposed. As the position of an under-tested point is unchangeIn consideration of the effect of the distortion error of an image on the accuracy of planar geometrical measurement in the precise visual metrology,a method to correct the image distortion by using standard grid board directly as measurement calibration is proposed. As the position of an under-tested point is unchanged relative to that of grid board when an under-tested object and a grid board lay on the same object plane, the grid board is directly used as the correcting calibration of image distortion instead of the way that converts the external standard into the intrinsic parameter of a camera by modeling .Firstly,the primary position of the under-tested point in the image of grid board is determined;then,its fine distance is decided according to the proportion theorem of line segment divided by parallel line.Finally, planar geometrical measurement is fulfilled by calculating the sum of both distances.Experimental results show that the distortion error by the proposed method has reduced to 20% that of the traditional method and the correctoin accuracy of image has reached 4 μm or higher, while the distance of intersection point of the calibrated grid board is 1 mm and its accuracy is 0.2 μm.The method is more applicable and has high accuracy,for it omits the modeling and its accuracy only depends on the calibrated grid board..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 19, Issue 1, 161 (2011)
Super-resolution reconstruction of image in high accuracy image measuring system
ZHANG Jin, WANG Zhong, LI Ya-jie, and YE Sheng-hua
To improve the measuring accuracy of an image measuring system,the super-resolution image reconstruction technology for an image sequence is researched based on the micro-displacement.As the high accurate micro-displacement is difficult to realize and very expensive, a super-resolution reconstruction method which doesnTo improve the measuring accuracy of an image measuring system,the super-resolution image reconstruction technology for an image sequence is researched based on the micro-displacement.As the high accurate micro-displacement is difficult to realize and very expensive, a super-resolution reconstruction method which doesn't require the high accurate micro-displacement is proposed. Firstly, the image sequence based on an arbitrary micro-displacement is obtained. Then, the accurate micro-displacement of image sequence is calculated by the feature points of a tested object or a template using a substrate. Finally, the high-resolution image is reconstructed by the mathematical model proposed in this paper for radiographic measurement. The experimental results indicate that when the image resolution is 4 times that of an original image,the measurement accuracy will promote 29% to 64% according to the different micro-displacements,which shows the method can reconstruct a high-resolution image including tested objects effectively, and can improve the accuracy of the system..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 19, Issue 1, 168 (2011)
Arbitrary shaped ROI image coding using Run-length coding and generalized Exp-Golomb coding
XU Yong, XU Zhi-yong, and ZHANG Qi-heng
A context adaptive tri-element Run length coding algorithm and an Exp-Golomb coding alogorithm were introduced.The Run-length coding was used to model the image wavelet coefficients and the Region of Interest(ROI) mask and to yield tri-element codes.Then, the conventional Exp-Golomb coding was expanded to encode tri-elA context adaptive tri-element Run length coding algorithm and an Exp-Golomb coding alogorithm were introduced.The Run-length coding was used to model the image wavelet coefficients and the Region of Interest(ROI) mask and to yield tri-element codes.Then, the conventional Exp-Golomb coding was expanded to encode tri-element codes from Run-length coding and to carry the ROI mask together. Based on the two algorithms above,a high efficient algorithm to distinguish the ROI and background was obtained and a ROI codec framework was proposed. The framework includes 5/3 wavelet transform, wavelet domain mask generation, non-uniform optimal quantization, context adaptive tri-element Run-length coding and generalized Exp-Golomb coding. The tri-element Run-length coding in this algorithm is brief, and the expanded Exp-Golomb coding can be expressed by a closed formula. Experimental results show that the algorithm supports multiple arbitrary-shaped ROI and the adjustability of the ROI is prior to that of the background region. Furthermore, it achieves higher compressing performance as compared with the BbB-shift based SPIHT compression algorithm..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 19, Issue 1, 175 (2011)
Moving object detection based on variant block difference in complex scenes
ZHU Juan-juan, and GUO Bao-long
A fast moving-object detection algorithm based on inter-frame Variant Compensated Blocks Difference(VCBD) is presented to deal with the complex scenes with camera scan, dithering and object moving. Firstly, the global motion estimation is performed based on feature points to compensate the inter-frame background. The gA fast moving-object detection algorithm based on inter-frame Variant Compensated Blocks Difference(VCBD) is presented to deal with the complex scenes with camera scan, dithering and object moving. Firstly, the global motion estimation is performed based on feature points to compensate the inter-frame background. The global feature points in a reference image are selected and matched in a current image. Then, the iteration is applied to realize the minimum sum of position errors of all matched points and to obtain the global motion parameter with the accuracy less than 0.5 pixel. Accordingly, the current frame is compensated to match the background area. Finally, the adaptive variant block difference is proposed to detect moving objects. The whole image is classified into background, foreground and boundary areas and the block is then judged with the threshold and divided into four blocks. These coarse-to-fine steps can greatly improve the velocity and veracity of detection. Experimental results show that the algorithm can detect moving objects in camera scan and dithering sequences and the processing speed achieves 25 frame/s..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 19, Issue 1, 183 (2011)
Application of multi-mode combined polishing to optical manufacturing
XUAN Bin, XIE Jing-jiang, and SONG Shu-mei
The multi-mode combined polishing technology based on traditional polishing and numerical control polishing methods was introduced. The simulation of material removal rate, one of the key processes of the multi-mode combined polishing,was described in detail. By setting the factors of laps and workpieces,the model for The multi-mode combined polishing technology based on traditional polishing and numerical control polishing methods was introduced. The simulation of material removal rate, one of the key processes of the multi-mode combined polishing,was described in detail. By setting the factors of laps and workpieces,the model for material removal rates involves not only polishing modes and polishing velocity but also the influences of the lap shape, edge effect and surface error on material removal rates. Furthermore,it can choose the different simulation precisions depending on the manufacture process. The practical results show that the multi-mode combined polishing technique provides high polishing efficiency and suppresses and reduces the ripple efficiently. The precision of surface error of optical spheres and flats can reach 20 nm (rms) and those of the aspheres can be 30 nm to 40 nm (rms) so far.Obtained results indicate that the multi-mode combine polishing is a proper technology for the manufacture of large components..
Optics and Precision Engineering
- Publication Date: Sep. 26, 2021
- Vol. 19, Issue 1, 41 (2011)
© Copyright 2018-2021 | Chinese Laser Press. All Rights Reserved 沪ICP备15018463号-20