Chinese Version Light学术出版中心
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Issue 8 ， 2011
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13.5 nm Schwarzschild microscope and imaging experiment
Abstract：A Schwarzschild microscope working at 13.5 nm was developed. According to the theory of a coaxial two-mirror system, the optical structure of Schwarzschild objective was designed by eliminating third-order spherical aberrations, coma and astigmatism. Experiments show that the spatial resolution of the designed objective achieves 550 lp/mm within the field of ±0.3 mm with respect to the calculation of modulation transfer function. Based on the working wavelength and incidence angle of lights,the Mo/Si multilayer optics with the reflectivity of 61% at 13.5 nm was designed and fabricated. In order to remove visible and ultraviolet lights,a filter with materials of Zr, Si and Si3N4 was designed and fabricated,and the transmittance of 21.1% was obtained at 13.5 nm. With the purpose of demonstrating the resolution of microscope, the 60 lp/mm grid backlit by laser produced plasma was imaged via the Schwarzschild microscope on a Charge Coupled Device (CCD), and the results show that the imaging system can offer the resolution of 3 μm in the 0.5 mm field.It concludes that the resolution of imaging experiment is limited by the resolution of CCD camera.Keywords：imaging system;Schwarzschild imaging microscope;Mo/Si multilayer;filter;spatial resolution- 56
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Published：2020-08-12 -
Interferometric alignment of imaging spectrometers with convex gratings
Abstract：How to align the spectral systems of Offner concentric imaging spectrometers with convex gratings was researched. Based on the principle of dual-beam interference and characteristics of concentric systems,an interferometric alignment method for the Offner imaging spectrometers with convex gratings was proposed.With this method ,the primary and tertiary mirrors of Offner imaging spectrometers were aligned firstly. As the defocus of single spherical mirror could not be aligned to zero,the relative defocus was introduced to adjust the defocuses of the two mirrors to achieve the concentricity. Furthermore,because the concave compensator could not test the convex mirror,the convex grating was arranged according to reading spectrogram directly to complete concentric alignment with high precision. The result indicates that the interferometric alignment can achieve the distance between centers of the primary and tertiary mirrors of Offner imaging spectrometers up to several nanometers or near zero.Keywords：imaging spectrometer;convex grating;interferometric alignment;direct-reading spectrography- 54
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Published：2020-08-12 -
Optical alignment of all-reflective afocal ZH optical system
Abstract：A co-axis and all-reflective afocal ZH optical system and its alignment method were introduced. The ZH optical system consists of a first paraboloid, a mirror with two operational faces and a 45° angle and a second paraboloid. The two paraboloids were installed from every end of the mirror,and the mirror with two operational faces was mounted easily. The tolerance and assembly of the ZH optical system were computed and analyzed, the effect of the position misadjustment of the element on the system was discussed, and the error analysis results were given. As there is an offset distance between the incidence optical axis and the shoot optical axis when the light propagates through the ZH system, a precision assembly method was proposed to ensure the parallel of the incidence optical axis and the shoot optical axis. In experiments, a visible collimator tube was used to align the ZH optical system, and the horizontal and vertical parallel offset lenses were taken to compensate the offsets. Moreover, a micro-displacement measuring module and a micrometer eyepiece were used to measure the adjusting size of the system. By the proposed method, the ZH system completes the co-axis of the incidence optical axis and the shoot optical axis. The parallel offset lenses were taken out after ZH optical was assembled, and the system can realize the space parallel of the optical axes.Keywords：optical system;all-reflective afocal ZH optical system;alignment;common optical axis- 51
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Published：2020-08-12 -
Material preparation, surface modification and aspheric processing of RB-SiC mirrors
Abstract：To solve the problems of RB-SiC mirrors in engineering applications, the material preparation, surface modification and aspheric processing of RB-SiC mirrors were analyzed. Firstly, according to the special modification characteristics of the RB-SiC mirrors, a new material whose thermal expansion coefficient was matched well with that of the RB-SiC was chosen to be a new support for the thermal design. Then, the modification and fabrication technologies of RB-SiC mirrors were improved based on the actual situation of the aspheric processing for better processing reliability and shorter processing cycle. Finally, the improvement were verified by experiments. The experimental results indicate that the modified RB-SiC mirror is in a good condition.The RMSs of the mirror surfaces before and after modifications have changed only 0.017λ(λ=623.8 nm,change rate in 13%),and the aspheric processing time has decreased 1 month or 2 months. The adequate margin of the 10 μm modified layer in the subsequent processing is ensured,the processing security is improved and the processing cycle of the aspheric is shortened due to the new technology,which can been applied to the preparation and processing of other aspheric SiC mirrors as well.Keywords：RB-SiC mirror;surface modification;aspheric processing;processing cycle- 40
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Published：2020-08-12 -
Coherent combining of two pulsed solid state lasers
Abstract：A coherent combining scheme for two solid state lasers was proposed by using Michelson cavity technique. Based on constructive interference and destructive interference properties of two beam interferences,this scheme implemented the passive coherent combination of two lasers in consideration of the gain loss of a cavity. The phase-locking principle was analyzed in detail and the phase-lockings of two individual pulsed solid state lasers were experimentally demonstrated.Finally, the coherent combination output energy of 300 mJ/pulse was obtained, and its combination efficiency was 80%. These results show that the coherent combining technique proposed in this paper is characterized by self-choosing and self-adjusting and can offer a high combination efficiency.The technique can also be used in multi-beam solid laser coherence combination,for it solves the problem on the duty ra- tio in coherent combination.Keywords：coherent combining;Michelson cavity;pulsed solid state laser- 55
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Published：2020-08-12 -
Measurement of three-dimensional attitude by single opto-electrical and radar integration instrument
Abstract：A single opto-electrical and radar integration system was designed and the feasibility to apply the system to measurement of three dimensional attitudes of flying targets was discussed. Then,the principles,algorithms and measuring errors of the system were researched. According to three-dimensional attitude computer methods, the system's key technical indicators were determined, and the effective distance and the attitude measurement accuracy of the system for a simulated target was analyzed. The results show that the effective distance to the simulated target distance is more than 60 km,and the real-time three-dimensional attitude measurement accuracy is less than 120'. By use of the exiting device,a single-station measurement experiment to the real-time three-dimensional attitude of the target was performed and the results show it is feasible to measure the three-dimensional attitudes of targets by single opto-electrical and radar integration instruments , which not only can improve measuring accuracy and working efficiency and also can eliminate the restriction for measuring instrument distribution.Keywords：three-dimensional attitude measurement;opto-electrical and radar integration;single station measurement;measurement accuracy- 51
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Published：2020-08-12 -
Measurement system of flexible electronic checking fixture on robot
Abstract：A new measuring system of flexible electronic checking fixture on an industrial robot was proposed to overcome the shortcomings of the real special checking fixtures commonly used in industrial production with high costs, poor flexibility and low automation. A vision sensor was fixed on the terminal tool of the industrial robot taken as the flexible automation platform.By teaching the robot to run the programmed measuring path,the every local sensor system was unified to the global system by global calibration technology.As the repetitive position error of the robot in this process is an important influencing factor on the overall system accuracy, an optical precise measuring method was presented to compensate the whole measuring results in real-time via measuring the repetitive position error by taking another camera as a control camera and combining with global control points fixed on the supporting assembly. Finally,the obtained results were campared with CAD digital module in a computer to realize the virtual flexible checking fixture function. Experimental result indicates that the overall three-dimensional root mean square (RMS) error of fourteen space points is 0.101 mm,which shows that the principle of method is reasonable. It overcomes the limitation of real checking fixture in high cost, heavy waste and accuracy affected by personal errors.Keywords：precision industrial measurement;flexible electronic checking fixture;industrial robot;close-range photogrammetry;Laser-vision measurement- 51
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Published：2020-08-12 -
Effect of vibration modes on positions of piezoelectric ceramic patches for cantilever generators
Abstract：By modeling and calculating the piezoelectric ceramic patches of cantilever generators,the effects of different positions of the piezoelectoic patches on the generation ability of the generators were analyzed and the optimum positions of the piezoelectric ceramic patches under the first and second vibration modes were obtained with Euler-Bernoulli model and by testing the open circuit voltages, short-circuit currents of generators and the performance of LED lighting. Experiments indicate that the generators show the optimum performance under the first vibration mode when the piezoelectric ceramic patches locate at the root of the cantilever. Its opening voltage and short current are 4 times and LED power is 10 times of experimental data of other three generators. Moreover,the generation ability is investigated under the second vibration mode. When the ceramic patch respectively locates at the middle and the root of cantilever, the generation ability of the former is superior to that of the latter,and the opening voltage and short current of the former are 1.2 and 1.9 times those of latters respectively through six generator experiments. In addition, LED power of the former is 1.4 times those of the others.It points out that the piezoelectric ceramic patches should be located at the root of beam under the first vibration mode and at the middle of beam under the second mode to improve the generation efficiency.Keywords：piezoelectric cantilever;ceramic patch;generator;vibration mode- 46
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Published：2020-08-12 -
Process of spherical photoresist spin coating
Abstract：A centrifugal coating technology was researched to coating the uniform thickness photoresist on a concave spherical surface. Firstly, the critical factors affecting the uniform of photosensitive resist and the film forming force were investigated. Then, the centrifugal glue adhesive force during the flow state was analysed in the spherical photoresist spin coating down opening based on the hydrodynamic theory. A mathematical model to describe the relationship among the film thickness and centrifuge speed, viscosity of photoresist and the spin coating time was derived. Finally, in order to verify the correctness of the formula , some experiments of photoresist spin coating on the K9 glass concave sphere with a diameter of 120 mm, radius of 300 mm, vector height of 12.5 mm were performed. The experimental results certify that the proposed theory is consistent with the actual situation well.On the theoretical analysis,the uniform film thickness on the inner surface of an entire sphere can be obtained with the disalignment of photoresis pin coating axis and the main axis of electric engine. When the viscosity of photoresist is 1.1~1.9 Pa and the speed of main axis is 3 000-6 000/r·min-1, the uniform film thickness is 0.5~1 μm on a concave sphere.Keywords：photoresist;centrifugal coating;hydromechanics;film thickness;Viscosity;Rotating speed- 60
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Published：2020-08-12 -
Fabrication of high fill-factor micro-mirror array with multi-terraced-plate structure
Abstract：In order to obtain a micro-mirror array with large torsional angles and large sizes under limited driving voltages, a novel micro-mirror array with a multi-terraced-plate structure was proposed and demonstrated based on the Micro-optoelectro mechanical System(MOEMS). The different characteristics of the electrostatic driver between multi-terraced-plate structure and parallel-plate structure were analyzed. The key fabrication process for the multi-terraced-plate structure was researched and a bulk micro-mechanical technology was used to fabricate a micro-mirror array with the multiterraced-plate structure.The obtained micro-mirror array contaning 52 micromirrors has the size in 600 μm by 200 μm, and a high fill-factor in excess of 97%. The test results show that the micro-mirror array achieves a maximum torsional angle about 1.1° under a driving voltage of 164 V,and the multi-terraced-plate structure greatly reduces the driving voltage as compared with the traditional parallel-plate structure.Keywords：Micro-optoelectromechanical System(MOMES);multi-terraced-plate;parallel-plate;electrostatic driving;micro-mirror array;high fill-factor- 40
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Published：2020-08-12 -
Optimizing design and precision experiment of focusing mechanism in lightweight space camera
Abstract：On the basis of the characteristics of optical systems in a space camera, a focusing mechanism suitable for the camera was designed optimally. Firstly, to meet the overall design requirements of the camera for the lower mass and smaller size, a double-slider mechanism combined a screw and a link was chosen to transform the screw's running into the line movement of the focusing mirror along the optical axis direction and to overcome the defocusing of the system by adjusting the image movement. Then, the focusing accuracy of the focusing mechanism was analyzed and the error source and error calculation were discussed. Finally, the vibration and accuracy tests were performed on the mechanism. It shows that the optimized focusing mechanism has a weight of only 2.5 kg and a shape size of 186 mm×144 mm×60 mm. Furthermore, the vibration and accuracy tests indicate that the focusing mechanism can offer the first frequency of 505 Hz, positioning accuracy of 0.008 mm, and the repeatability positioning accuracy of 0.002 5 mm, respectively. These results satisfy the requirement of the optical system very well and show that the mechanism is characterized by the compact structure, high stiffness and good accuracy.Keywords：space camera;nonlinear focusing mechanism;accuracy test- 43
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Published：2020-08-12 -
Solution of angle increments for roll-pitch seekers based on Paden-Kahan sub-problems
Abstract：The kinematic representation of a rool-pitch seeker was analyzed according to the special structure of the seeker. A geometrical closed-form angle increment solution was proposed based on the Paden-Kahan sub-problems. Using this method, the angle increment solution of the seeker was decomposed into two canonical Paden-Kahan subproblems,which led the solution of inverse kinematics to be two simple rigid motions.Therefore, the complexity of the inverse kinematics problem was reduced. Because the inverse kinematics of the seeker has not an exclusive solution, the minimum angle increment criteria was introduced to optimize the inverse kinematics problem. The numerical simulation shows that the obtained angle inerement allows the pointing error of an optical axis into zero,and the optical axis can be coincident with the line of sight very well. Finally,the semi-physics tracking experiments using the angle increment algrithom for a circle track target were performed,which demonstrates the effectiveness of the proposed inverse kinematics in solving the roll-pitch angle increment.Keywords：roll-pitch seeker;solution of angle increment;Paden-Kahan sub-problem;inverse kinematics- 41
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Published：2020-08-12 -
Development of non-perpendicular 2D MEMS tilt mirrors
Abstract：To improve the efficiency of optical conversion and spatial adaptability of conventional 2D tilt mirrors, non-perpendicular 2D MEMS tilt mirrors were presented in this paper. The designed mirrors were fabricated by PolyMUMPS process and their upper electrodes were asymmetrically fixed on a substrate.The deformation of mirrors tilted around two non-perpendicular axes were controlled by applying voltages. By constructing mirrors with three-layer membranes, effects of the upper electrode’s deformation on the flatness of the mirror surfaces were eliminated. By fabricating dimples on the upper electrode and reducing the overlapped area of mirrors’ electrodes on the edges of the upper electrode, the damage caused by the pull-in effect was eliminated. Furthermore,the designed electrodes made sure that forces produced by the applied voltages would produce large moments. The developed mirrors lower the working voltages, their tilting angles around X- and Y- axes are 0.16° and 0.03° at 3.5 V,respectively, and the angle between X axis and Y axis is 145.37°. It concludes that the mirrors can rotate around two non-perpendicular axes independently, and its advantages are simple structures and good spatial adaptability.Keywords：non-perpendicular tilt mirror;2D tilt mirrors;Micro-electro-mechanical System(MEMS)- 52
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Published：2020-08-12 -
Burst pressure of capillary burst valve based on glass and PDMS
Abstract：As the current simulation methods for capillary burst valves can not exactly calculate the burst pressure when the passive valve is limited by a glass flat cover with good hydrophilicity,a method to analyze the critical pressure of the passive value was proposed. The Surface Evolver (SE) was used to simulate the burst pressure of the microvalve composed of a glass cover and PDMS microchannels by setting the properly boundary conditions and monitoring the variation of the contact angle at the entrance of expansion section.In simulation, the liquid contact line should be set up the entrance of expansion section and come into the expansionary walls that connect the glass cover. Experiments show that the capillary burst pressures are 0.77, 0.45, 0.33 and 0.24 kPa, respectively, for the microvalves with the depth of 25 μm and the aspect of 2, 4, 8 and 16. The obtained simulation data are well in agreement with that obtained by a rotating platform. The effect of the contact angle for the capillary burst valve was also discussed,which points out that the valves do work until the sum of the contact angles on both the flat cover and the channel wall is greater than 90°.Keywords：microfluidic;capillary burst valve;burst pressure;surface evolver- 44
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Published：2020-08-12 -
Design of exact constraint micro-motion angle displacement mechanism with two degrees of freedom
Abstract：In order to design a micro-motion angle displacement mechanism for precision engineering,the degrees of freedom and constraint patterns of 3HSE and 3HSVR angle displacement mechanisms with three screws were analyzed,and it shows that the common angle displacement mechanisms designed via three point supports have the uncertainties of the orientation and motion. Therefore, an exact constraint angle displacement mechanism with double screws was presented. The mechanism is exactly constrained by six point constraints, so that the position and orientation are deterministic at the natural state. Moreover, the number of degrees of freedom of the mechanism are equal to the number of the inputs and its motion is also deterministic at the input state. Furthermore,the adjusting orientation principles under different inputs were proved and the sensitivity was analyzed via the relationship of kinematic geometry. The result indicates that the sensitivity of the mechanism is superior to 0.83 μrad. The analysis shows that the proposed angle displacement mechanism has good stability and is suitable for the angle adjustment involving two degrees of freedom in precision engineering.Keywords：angle displacement mechanism;Degree of Freedom (DOF);exact constraint;orientation;leveling- 47
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Published：2020-08-12 -
Rapid hand-eye calibration of dual robot system
Abstract：For the hand-eye calibration of a dual robot measurement system, a method based on machine vision to calculate the target robot flange pose and center coordinate was presented. By moving the target robot flange to a proper pose to take an image by the camera and extract the ellipse contour of the flange in the image to calculate the flange pose and its circle center data, the coordinate transform H 1 between camera coordinate system and flange coordinate system was obtained by using the location of pinhole on the flange. Then,the coordinate transforms between flange coordinate system and robot base coordinate systems ,namely, H 2 and H 4,are gotten,respectivity, from the robot controllers. Furthermore,the coordinate system transform H 3 between two robots were derived from single axis movements of robots, so that a hand-eye expression H CG was obtained to calculate the hand-eye coordinate transform. Finally,by moving the target flange to some coplanar poses to take their images, the calibration accuracy was improved by image fusion. Experimental results indicate that the cal ibration precisions of single image and coplanar poses using image fusion are 0.345° and 0.187°,re- spectively. It can satisfy the the requirements of dual robot systems for vision guiding measurement.Keywords：robot;hand-eye calibration;coordinate transform;image fusion;Circle pose- 39
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Published：2020-08-12 -
Application of spectral domain optical coherence tomography to oral cavity tissue test
Abstract：On the basis of the concept of Spectral Domain Optical Coherence Tomography (SDOCT),a fiber type SDOCT system which is easy to integration was developed. The system shows its longitudinal resolution in 7.3 μm, lateral resolution in 9.5 μm and offers the imaging depth to be 3.14 mm in air. The system obtains the sample deeply by a interferometer, which achieves the dada collection fast. The organizational features of salivary glands were researched by the above system, and the OCT images for the parotid glands were compared with that of the pathological section. Results show that the system proposed can provide a direction for the early diagnosis and the non-harmful examination of the oral cavity tissue.Keywords：Optical Coherence Tomography (OCT);spectral-domain;parotid gland;histopathology- 41
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Published：2020-08-12 -
Optimization of bandwidth for phase-locked loop in OTU
Abstract：As both the external input jitter and the internal phase noise jitter impact on the bandwidth of Phase-Locked Loop(PLL) in an Optical Transponder Unit(OTU), the bandwidth of the PLL was designed optimally to solve the contradiction of the wavelength selection. With consideration of the external input jitter and the internal phase noise, the bandwidth algorithm of the PLL was comprehensively analyzed, and an optimization algorithm of the bandwidth for PLL in the OTU was deduced through improving calculation and analytical methods from formers. The optimal bandwidth of the PLL can ensure the lower jitter noise of clock output in the OUT. The optimization algorithm was applied in the OTUs with 2.5 Gbit/s and 10 Gbit/s ,respectively to analyze the loop parameters and the optimal parameters of the PLL and the output jitter value of a regenerator were acquired quantitatively and qualitatively. The experiment shows that the optimization algorithm is superior to traditional algorithms and more suitable for OTUs.Keywords：Phase-locked loop(PLL);optimization algorithm;Noise;bandwidth;jitter- 56
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Published：2020-08-12 -
Filtering method of improving quality of grating Moiré fringe
Abstract：A filtering method, phase-difference filtering, was presented to improve the quality of grating Moiré fringe.Each field of the 4 field scanning reticle was devided into multi-lines with different phases to suppress the high harmonic generations and to improve the signal quality of the Moire fringe. Firstly, the Fourier series expression of Moiré fringe was introduced and various harmonic generations of the Moiré fringe were analyzed. Then, the filtering method to eliminate the second, third and fourth harmonic generations was illustrated with the designed grating patterns. Finally, the validity of the method to inhibit the high harmonic generations was verified through simulations and experiments. Experimental results indicate that the third harmonic generation of the Moiré fringe signal can be reduced by 4.9% and the accuracy can be improved by 0.5 μm with the period of 20 μm. The method is effective, low cost, without increasing the system size and easy to be used in industrial productions.- 82
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Published：2020-08-12 -
Real-time full-frame digital image stabilization system by SURF
Abstract：To overcome the undesirable shakes or jiggles of a camera and to implement the image stabilization in real time,a real-time full-frame video stabilization system based on the Speeded Up Robust Features(SURF) was proposed.Firstly,the SURF was employed to extract feature points,and the correspondence between the current and reference frame was established to get high precision local motion vector estimation. Secondly, by determining the reference frame update strategy, the smoothed interframe global motion vector was obtained. Finally, the corresponding pixels of the reference frame was filled with a stablized frame to compensate the unstable motion and to output an stablized full-frame video. Experimental results show that the real-time full-frame video stabilization system using SURF algorithm can provide the high accuracy (lower than 1 pixel) and short processing time (less than 30 ms). Moreover,it has a higher robustness on serious motion-blur and better image quality.Keywords：digital image stabilization;full-frame;SURF algorithm;motion estimation;motion filter;sub-pixel- 84
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Published：2020-08-12 -
Total variation image restoration for mixed blur in moving image
Abstract：In order to restore the image in the video frame of a moving image, the mixed blur that combines two common blur types, motion blur and defocus blur, was discussed. Firstly, blur types were determined according to the difference in spectrum features and the Point Spread Function (PSF) was estimated quantitatively using the cepstrum analysis. Blur parameters in simulation experiments were chosen based on engineering to verify the accuracy of the cepstrum analysis in the PSF estimation method. Then, a gradient fidelity term was coupled with total variation image restoration algorithm to constrain the impact of the PSF estimation error on image restoration and the Split-Bregman algorithm that is compatible with the L1 norm was adopted to accomplish the numerical computing in restoration algorithm. Finally, the simulation experiments and the real image restoration were carried to verify the performance of the algorithm. The results show that cepstrum analysis for estimating the PSF has an accuracy rate of 90%.The proposed algorithm can preserve edges and details, inhibit the ringing effect effectively and shows its Peak Signal to Noise Rate (PSNR) to be 28.92 dB.Keywords：motion blur;defocus blur;cepstrum;Total Variation (TV) image restoration;gradient fidelity term- 57
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Published：2020-08-12 -
Dual dictionary sparse restoration of blurred images
Abstract：An image restoration method based on a dual dictionary was presented under the framework of sparse theory,and the choice of overcomplete dictionaries and the implementation of iteration methods were analyzed. Firstly, the degradation and the restoration models in the sparse theory were established,then the dictionary constructed by Haar coefficients was used to sparse the blurred image and shrink the image with Parallel Coordinate Decent(PCD) iteration algorithm to obtain the elementary deblurred image,in which the blur was removed efficiently, but the noise was weighted and added. For removing the weighted noise, the secondary dictionary from an image database was trained to shrink the deblurred image and get the final result. The results shows that the proposed method can restore the motion-blurred image efficiently, remove motion blur and noise and reserve the edge detail in some extents. Finally the two-level sparse optimization model was expanded and a new idea for the image restoration was presented under the sparse framework.Keywords：image restoration;sparse representation;overcomplete dictionary;Haar wavelet;norm;iteration shrink/threshold algorithm- 66
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Published：2020-08-12 -
Camera calibration in morphology measurement of axisymmetric body
Abstract：In order to realize automatic calibration of the camera used in morphology measurement of axisymmetric body, the perspective projection characteristics of the axisymmetric bodys are investigated, and an automatic intrinsic and extrinsic parameter calibration method of the measureing camera is proposed based on self constraint characteristics of measured axisymmetric body. First, utilizing the ease of extration of the section fetures, the ellipses of the image of the axisymmetric body cross sections are estimated, and used to cauculate the images of the circular points. Combining with the epipolar constraint, the full constraint equations of the image of absolute conic are established. Once the image of absolute conic is computed, the camera intrinsic parameters are obtained by Cholesky’s factorization. Second, the extrinsic parameter equations are established using the image of the symmetry axis and cross sections based on the intrinsic matrix of the camera and the extrinsic parameters are solved. Experimental results indicate that the relative precision of the cauculated intrinsic parameters is better than 0.95% and the extrinsic parameters 5.6%. It utilizes only the axisymmetric constraints of the measured object without the calibration plate or block. The calibration process is simple and effective, can satisfy the real needs.Keywords：epipolar constraint- 60
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Published：2020-08-12 -
The embedded implementation of real-time finger interaction system
Abstract：In order to meet the need of human-machine interaction of the portable equipments, an embedded finger-interaction system is implemented. Its applied algorithms such as skin color segmentation, convex hull computation, fingertip detection and etc have been investigated and the hardware has been designed. Firstly, according to the clustering character of skin color, the human hand is segmented via building the skin color model by analyzing the characters of common color spaces. Secondly, the classic Graham-scan method is improved based on the method of radial-scan, and the convex hull of human hands can be computed quickly. Thirdly, the algorithm of fingertip detection which uses the curve of human finger is discussed. Finally, the DSP and FPGA based hardware structure is introduced. Experimental results indicate that the detecting precision is 95.2% for a natural stretched finger, is 92.6% for the bended finger and is 90.1% under the disturbance of other fingers. The maximum offset of fingertip location is 2.12mm and the location time is 23ms. The system is nature and friendly, has strong stabilization and can satisfy the real-time requirement.Keywords：Graham scan- 34
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Published：2020-08-12 -
Modeling and experimental verification for a cantilevered piezoelectric vibration energy harvester
Abstract：The mathematical model with high accuracy for cantilevered piezoelectric vibration energy harvesters needs to be established to optimize the harvesters according to the characters of the environmental vibration and the electrical loads. The motion differential equation and the boundary conditions for a cantilevered piezoelectric vibration energy harvester were established, in which the position difference between the center of the proof mass and the free end of the cantilever is considered. A uniform coupled circuit equation, which is applicable to the cantilevered piezoelectric vibration energy harvester with one piezoelectric layer, two series connected piezoelectric layers and two parallel connected piezoelectric layers, was developed by introducing several constants. The expressions of the natural frequencies and corresponding mode shapes were obtained. The closed-form expressions of the output voltage were derived for harmonic base accelerometer excitations and arbitrary base accelerometer excitations. Experimental results show that the relative errors of the natural frequency expression and the output voltage expression are smaller than 10% and 20% for three harvester prototypes, which satisfy the requirements of the optimization of the harvesters.Keywords：modeling- 27
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Published：2020-08-12 -
Parameter Adaptive Illumination Robust Feature Extraction Transform
Abstract：Most feature extraction algorithms are highly sensitive to illumination variations. This paper presents a parameter adaptive illumination robust extraction transform (PA-IRFET) which is based on the histogram of the image. The method includes three steps: firstly, the gray transformation function and parameters are determined based on the analysis of the histogram of the image. Then, the function is used to transform the image to build illumination-space. Finally, the illumination-space is combined with feature extraction algorithms to detect illumination robust features. In the experiment of this paper, PA-IRFET is combined with Harris detector. PA-IRFET improves the number of detected features of IRFET greatly and improves the repeated features of IRFET by around 20% on average. This demonstrates that PA-IRFET is more robust to illumination variation than IRFET.Keywords：Harris detector- 44
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Published：2020-08-12 -
All attitude magnetic deviation compensation for digital magnetic compass
Abstract：In order to overcome the shortcomings of high cost, low efficiency and insufficient tilting compensation ability from the existing magnetic deviation compensation methods, a new method based on geometric transformation was proposed to compensate the digital magnetic compass. First, the effect of the magnetic interference on the output of magnetic sensors was analyzed and a geometric transformation model for the compass deviation was established. Based on the model, the number of magnetic deviation parameters was reduced from 12 to 9. Second, a hybrid algorithm for solving these 9 parameters was proposed, where the Particle Swarm Optimization(PSO) algorithm was applied to adjust the initial value and the Newton algorithm was used to accelerate the convergence process. Finally, the compensation method was used to compensate the magnetic heading error. The experimental results show that the method mentioned achieves good effects and performs better than that of traditional compensation methods. The compensation time is less than 3 minutes and the magnetic heading error is 1/8～1/10 little than the one before compensation. It can satisfy the requirement of the attitude and heading reference system.Keywords：parameter optimization- 35
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Published：2020-08-12
Article
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Adaptive optical wave-front processor based on FPGA
Abstract：In accordance with the need of a larer ground-based high resolution imaging telescope for adaptive optical wave-front processing,an Adaptive Optical(AO) wave-front processing system with larger calculation and thousands of units was designed based on the Field Programming Gate Array(FPGA) and its operation scheme,implement processing and tested results were given. At the software,the FGPA was used to configure and control data and to realize the conversion and transmission of multi-channel D/A data synchronously. Meanwhile,the FPGA was taken as a key element to preprocess the image and calculate the wave-front gradient of a sub-aperture.With satisfied wave-front processing precisions,it shortens wave-front processing delay and improves the ability of wave-front processing. Results demonstrate that the system can achieve the wave-front processing in 2 000 frame/s. At the hardware,this system combined the wave-front processing host board and wave-front processing sub board to improve the output ability of the system. As each wave-front processing sub board can promote the output of 120 road and the maximum expansion capacity of the main board is 10,the system can reach the momentum of the output in 1 200 road.Keywords：adaptive optical system;Field Programming Gate Array(FPGA);Wave-front processor- 70
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Published：2020-08-12 -
Helicopter-borne laser autonomous positioning of buried pipeline
Abstract：To realize the remote detection of the leak of a buried natural gas pipeline by an airborne laser,a helicopter-borne laser autonomous positioning method for the buried natural gas pipeline was presented. Based on the position and attitude of the carrier aircraft obtained by an airborne GPS and an inertial attitude measurement system,the laser autonomous positioning point of the pipeline was obtained based on the known location information and by the space vector method. Furthermore,the azimuth and pitch angles of the airborne laser were solved through the coordinate transformation. Finally,driven by the mechanism,the laser-guiding positioning of the pipeline was fulfilled. With application of the laser clamping alignment mechanism independently developed by ourselves,the ground point-fixed experiment proves that the proposed algorithm can offer the accuracy of the ground positioning by 6.9 m,and it will be more accurate when the precision of the carrier aircraft attitude and the position sensor is further improved. Experiments demonstrate that the algorithm is suitable for the remote detection of the buried natural gas pipeline by airborne lasers.Keywords：airborne laser;buried pipeline;remote detection;autonomous positioning;coordinate transformation- 85
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Published：2020-08-12 -
Design of very high accuracy star simulator
Abstract：A very high accuracy star simulator system with the simulation accuracy less than 0.2″was developed to implement the ground calibration and accuracy testing for an Optical Sensor of Autonomous Navigation (OSAN). The simulator utilizes a high-precision and large size star array target to simulate a star map on the focal plane,and takes a luminescence controllable LED array as the illumination system of the target. Furthermore,it uses a long focal length and large FOV collimator as the projection optical system to control the star map on the target to be alterable and to project from the collimator exit pupil in parallel. Finally, the very high accuracy star map is simulated successfully. A testing method of light projection accuracy is proposed, by which the accuracy level of theory analysis is better than 0.14″. Obtained result indicates that the star simulator can satisfy the requirements of ground calibration and accuracy testing of the OSAN.Keywords：star simulator;ground calibration;star sensor;starlight projection precision- 55
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Published：2020-08-12 -
Preparation of RB-SiC blank and fabrication of its surface modification aspheric mirror
Abstract：In order to solve the engineering problems that exposed during the RB-SiC fabrication and shorten the processing cycle of aspheric, the RB-SiC mirror preparation, surface modification and aspheric processing techniques were analyzed. First, according the special modification characteristic of the RB-SiC mirror, the researchers chose a new material that its thermal expansion coefficient was matched very well to the RB-SiC thermal expansion coefficient. Then the modification and fabrication technology of RB-SiC were improved based on the actual situation of the aspheric processing in order to improve the reliability of the processing and shorten its processing cycle. Finally, the improved technology and methods were verified by the experiment. And the experimental results indicate that the modified RB-SiC mirror is in a good condition and RMS of the mirror surface modified before and after changed was only 0.017λ（λ=623.8nm）,13% rate of change and the aspheric processing time decreased 1 month or 2 months. The new technology ensured that adequate margin of the 10μm modified layer thickness in the subsequent processing and made the modified layer to be ground leakage difficultly. The security of the processing was improved and the processing cycle of aspheric was shortening in the engineering practice. The new technology can been applied to other SiC mirror preparation and processing of aspheric very well.Keywords：processing cycle- 57
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Published：2020-08-12 -
Principle and Application of Interferometrical Optics Alignment of Imaging Spectrometers with Convex Grating
Abstract：Spectral system of Offner imaging spectrometers with convex grating utilizes only three spherical and centred surfaces achieving anastigmat , small spectral and spatial distortion, compact size and large numerical aperture. Concentric alignment with high precision is the key to realize these advantage. Based on the principle of dual-beam monochromatic interference and concentric system, interferometrical optics alignment for Offner imaging spectrometers with convex grating is given.With this method ,the primary and tertiary mirror of Offner imaging spectrometers achieve concentric, the convex grating is arranged according to reading spectrogram directly and concentric alignment with high precision is realized. By the result, interferometrical optics alignment can achieve the distance between centers of the primary and tertiary mirror of Offner imaging spectrometers several nanometer or near zero.- 46
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Published：2020-08-12 -
Imaging experiment of 13.5 nm Schwarzschild microscope
Abstract：Abstract: A Schwarzschild microscope working at 13.5 nm is developed. According to the theory of coaxial two-mirror system, the optical structure of Schwarzschild objective is designed by eliminating third-order spherical aberrations, coma and astigmatism. Spatial resolution of the designed objective achieves 550 lp/mm within the field of ±0.3 millimeter with respect to the calculation of modular transfer function. Based on the working wavelength and incidence angle of light, Mo/Si multilayer optics with reflectivity of 61% at 13.5 nm is designed and fabricated. In order to remove visible and ultraviolet light, filter with material of Zr, Si and Si3N4 is designed and fabricated, transmittance of the filter at 13.5 nm is 21.1%. With the purpose of demonstrating the resolution of microscope, the 60 lp/mm grid backlit by laser produced plasma is imaging via Schwarzschild microscope on charge coupled device (CCD), and the results show that the imaging system can achieve the resolution of 3 μm in the 0.5 mm field. The resolution of imaging experiment is limited by the resolution of CCD camera.Keywords：spatial resolution- 27
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Published：2020-08-12 -
Optical Alignment of a Novel ZH Optical System
Abstract：A novel ZH optical system and its' alignment research is presented in this paper. The ZH optical system consists of a first paraboloid, a mirror with two operational faces and 45° angle, a second paraboloid. The two paraboloids have a common focus plane. The mirror with two operational faces has a central small hole, the small hole is located at the common focal plane of the two paraboloids, the coefficient of obstruction of the ZH optical system minimized, the focal plane of the two paraboloids is the immediate real image plane of the ZH optical system, the central small hole can be used the aperture of the field of view and the aperture of the obstruction, the centre of the small hole is common axis with the optical axis of the two paraboloids. The two paraboloids can be installed from every side respectively, which avoid the difficult problem of assembly of the second mirror of the Cassegrain. There is an offset distance between the incidence optical axis and the shoot optical axis of the ZH optical system because of the mirror with two operational faces' thickness. The offset is compensated by parallel offset lens, which realize system common axis. The parallel offset lens are taken down when ZH optical system is assembled. Based on the ZH optical system, the MWIR polarization image optical system is assembled and the MWIR polarization image is presented. The ZH optical system can be used in the MWIR polarization imaging optical system and the SWIR polarization imaging optical system. The paraboloids and the mirror with two operational faces avoid the difficult problem of plating wide waveband anti-reflective coating in the surfaces of lens. The dual waveband polarization imaging optical system realize common aperture in its' first telescope because of the ZH optical system.Keywords：common optical axis- 29
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Published：2020-08-12 -
Experimental study of coherent combining of two pulsed solid state lasers
Abstract：Coherent combining of solid state lasers is studied experimentally by using technique. The phase-locking principle is analyzed in detail and the phase-locking of two individual pulsed solid state lasers is experimentally demonstrated. The coherent combination output energy is of 300mJ/pulse, and the combination efficiency is of 80%. These results show that the method is one of the most promising phase-locking technologies and can be scaled to a large number of lasersKeywords：pulsed solid state laser- 30
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Published：2020-08-12
Modern applied optics
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Influence of adjustment error on wavefront aberration in off-axis paraboloid test
Abstract：Optical tests for the off-axis aspherics in optical processing and optical assembling were researched and the effect of adjustment errors on the wavefront aberration was analyzed. By taking an off-axis aspherics with the radiu of 10 000 mm,quadratic surface coefficient of -1,diameter of 500 mm and the lateral displacement of 425 mm for an example, the physical model and mathematical model to describe the relationship between the adjustment parameters and the wavefront aberration were estabished. The adjustment parameters included the pitch and high-low errors, beat and off-axis distance errors,and the rotating parameters around the secondary optical axis. The matlab software was used to simulate the influence of the wavefront aberration on the adjustment errors.Then, the experiments were performed to examine the simulation results.It shows that the the simulation results are well concident with the experiment ones, which proves the theory model in correct. The obtained results are also suitable for the test and alignment of other off-axis aspherics.Keywords：off-axis aspherics;optical testing;wavefront aberration;Adjustment error- 50
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Published：2020-08-12 -
Image motion compensation of three-line stereo mapping camera using earth ellipsoid
Abstract：The imaging principles of a three-line stereo mapping camera was analyzed. To overcome the differences of image motion speeds and drift angles of the forward-view camera, nadir-view camera and backward-view camera, the calculation formulas of image motion speeds and drift angles for forward-view, nadir-view and backward-view cameras based on an ellipsoid model were deduced.By taking a three-line stereo mapping for an example and using the WGS84 earth ellipsoid model,the influences of image motion speed matching remains and drift angle remains on the image quality of a three-line stereo mapping camera were analyzed when the forward-view and backward-view cameras both adjust the row transfer periods and drift angles same as the nadir-view camera. Results indicate that with 5% reduction of MTF as a constraint, if more than 2 TDI stages are used nadir-view camera, the forward-view and backward-view cameras should adjust their row transfer periods respectively; However,if drift angles of forward-view and backward-view cameras are adjusted according to nadir-view camera, TDI stages should be no more than 40.Keywords：three-line camera;stereo mapping;image motion compensation;earth ellipsoid;Modulation Transfer Function(MTF)- 60
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Published：2020-08-12 -
Calculation of magnetostrictive coefficient of composite thin film and structure optimization of cantilever
Abstract：A model to solve the magnetostrictive coefficient of a Giant Magnetostrictive Film(GMF) was established to analyze the coupling relations of GMFs.Then,the building process, deduction mechanism and simulation results of the model were investigated. On the basis of magnetostrictive coefficient expression of a single layer GMF, the magnetostrictive coefficient expression of a composite GMF was obtained by simplifying the deformation of the composite GMF reasonablely.By taking the compound GMF with positive and negative magnetostrictive effects as the research object, the impact of magnetostrictive coating thickness on the deflection of the free end of the cantilever GMF was discussed by using the deduced magnetostrictive coefficient expression. The results show that the deformation capability for both Cu-based thin film and PI-based thin film can reach the maximum when the total thickness ratio of the positive and negative magnetostrictive material layers is 2.3,which realizes the structure optimization of positive and negative cantilevers.Keywords：composite Giant Magnetostrictive Film(GMF);magnetostrictive coefficient;structure optimization- 42
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Published：2020-08-12 -
Precision analysis and process implementation of angular displacement sensor based on flexible varied line-space grating
Abstract：An angular displacement sensor based on a flexible varied-line-space grating was developed for the fly-by-light flight control system. The main factors effecting on the sensor precision and the process for sensor fabrication were discussed. Firstly, the principle of the sensor was introduced based on the key role of cylindrical varied-line-space grating played in the displacement sensor. Then, the effects of process errors on sensor precision were analyzed, and a conclusion was pointed out that the inner surface roundness of the cylindrical varied-line-space grating should be limited to be less than 0.01 mm when it was shaped from the flexible varied-line-space grating. According to analysis results, an accurate forming process was adopted, and its feasibility was conformed by ANSIS analysis. Experimental results show that the inner surface roundness of the sensor can be 0.004 3 mm, and the sensor linearity can be 0.27% of the full range.Obtained results meet the precision requirement of the aero-sensors.Keywords：flexible varied-line-space grating;cylindrical varied-line-space grating;angular displacement sensor;elastic punch- 56
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Published：2020-08-12 -
Error valuation for mode analysis of reflective mirror set
Abstract：The error caused by Finite Element Analysis(FEA) in the mode analysis of a reflective mirror set was evaluated quantitatively and identified by an experiment. The influence of source factors, arithmetic error, material parameter error and the simplification of the bolt connection on the FEA results were introduced in detail.It shows that the arithmetic error is less than one percent; the deliver factors of the material parameter errors can be calculated by the formula and test calculation dada, respectively,and the participation factors of the material parameter errors are estimated by the modal plot; the error caused by the simplification of the bolt connection is calculated by the contrast of the results of the simplification finite element model and the detailed finite element model. The results show that the FEA error would be 10% if the bolt connection is simplified.However, if the bolt connection is considered in detail,the FEA error would be decreased to 5%. The experiment results prove that the error analysis results are correct. Moreover,the trade method of the bolt connection is the key factor in the mode analysis of the reflective mirror set and it can’t be ignored apparently in the high precision analysis. It concludes that the quantitative error valuation method can be applied to the other cases, such as gravity transformation analysis, dynamic response analysis and thermal analysis.Keywords：Mode analysis;error deliver factor;error participation factor;Bolt connection- 53
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Published：2020-08-12 -
Angle increment solution for roll-pitch seeker based on Paden-Kahan sub-problems
Abstract：A representation of the seeker gimbal kinematics is analysed for the roll-pitch seeker. A geometrical closed-form angle increment solution has beem proposed based on the Paden-Kahan sub-problems. Using this method, the angle increment solution of the seeker is decomposed into two canonical Paden-Kahan subproblems. The subproblems lead to solution of inverse kinematics which consists of simple rigid motions, the complexity of the inverse kinematics problem is reduced. Because inverse kinematics of the seeker has not an exclusive solution, the minimum angle increment criteria is introduced in optimizing the inverse kinematics problem. The semi-physics tracking experiments using the angle increment algrithom for circle track target are provided to demonstrate the effectiveness of the proposed inverse kinematics in solving roll-pitch angle increment.Keywords：inverse kinematics- 49
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Published：2020-08-12 -
The effect of vibration modes on location of piezoelectric ceramics patch for cantilever generator
Abstract：In order to find the most appropriate location of the piezoelectric ceramics patch under the first and second vibration modes, the position of piezoelectric patch is discussed in the first and second modes with Euler-Bernoulli model. Through testing the open circuit voltage, short-circuit current of generator and the performance of LED lighting, the best position of the ceramics patch is obtained. When the piezoelectric ceramics patch locates at the root of cantilever, generator shows the best performance under the first vibration mode. Compared with experimental data of other three generators, opening voltage and short current are 4 times higher and LED power is 10 times higher. Moreover, generation ability is investigated under the second vibration mode. When ceramics patch respectively locates at the middle and the root of cantilever, the generation performance of the former is superior to the latter. Opening voltage and the short current of the former are 1.2 and 1.9 times higher respectively through six generators experiment. In addition, LED power of the former is 1.4 times more than that of the other. In order to improve generation efficiency, piezoelectric ceramics patch should be located at the root of beam under the first vibration mode. Nevertheless, piezoelectric ceramics patch should be located at the middle of beam under the second mode.Keywords：vibration modes- 40
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Published：2020-08-12 -
Optimize Design and Accuracy Test of Focusing Mechanism of Lightweight Space Camera
Abstract：In order to make sure that the space camera has an extensive application and positioning accuracy of ground targets the focusing control systems should be designed to compensate the defocusing of the CCD plane in the space camera. First, in the interest of the low weight and miniaturization which are requested by the collectivity of the camera, we choose the scheme of screw to collectivity the link which changes the screw's running to the line movement of the glass. Then, the error analysis is done for the focusing mechanism and the source of the error is discussed. Finally, the vibration test and accuracy test are implemented on the mechanism. The optimized focusing mechanism has a weight of only 2.5Kg and a shape size of 186mm×144mm×60mm. The results of vibration test and accuracy test show that the first frequency of the focusing mechanism is 505Hz, the positioning accuracy of this focusing mechanism is 0.008mm, and the repeatability positioning accuracy is 0.0025mm, which satisfy the requirement of the optical system very well. This implies that our focusing mechanism has the characteristics of the compact structure, high stiffness and accuracy, which greatly meet the needs of the space camera.Keywords：accuracy test- 60
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Published：2020-08-12 -
Study of Non-perpendicular 2D MEMS Tilt Mirrors
Abstract：Objetive: To improve the efficiency of optical conversion and the spatial adaptability of conventional 2D tilt mirrors, non-perpendicular 2D MEMS tilt mirrors were presented in this paper. Method: Mirrors were fabricated by POLYMUMPS process and their upper electrodes were asymmetrically fixed on the substrate, mirrors were tilted around two non-perpendicular axes by applying voltages. By constructing mirrors with three layer membranes, effects of the upper electrode’s deformation on the flatness of the mirrors’ surface were eliminated. With the aids of dimples fabricated on the upper electrode and the small overlapped area of mirrors’ electrodes on the edges of upper electrodes, limitations by the pull-in effect were eliminated. The designed electrodes would make sure that forces produced by applied voltages to produce large moments. Result: The working voltages of mirrors were low, at 3.5 V, the tilting angles of mirrors around X- and Y- axis were 0.16o and 0.03o , respectively, the angle between X axis and Y axis was145.37o . Conclusion: The mirrors rotate around two non-perpendicular axes independently, the advantages of this design are simple structures, big reflective mirror surfaces and good spatial adaptability. Moreover, the pull-in effect of this mirror is eliminated.Keywords：2D tilt mirrors- 29
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Published：2020-08-12 -
Fabrication research of a high fill-factor micro-mirror array with multi-terraced-plate structure
Abstract：Micro-mirrors array is one of the most important devices in the Micro-Optical Electro Mechanical system (MOMES) field. It can be widely used in various macro optical areas, such as Optical communication, Adaptive optics, projection or imaging, etc. In order to obtain a micro-mirror array with large torsional angle and large size of micro-mirror under limited driving voltage, in this paper, we propose and demonstrate a novel MOEMS micro-mirror array with multi-terraced-plate structure. The difference characterization of electrostatic driver between the multi-terraced-plate structure and parallel-plate structure are analyzed. The multi-terraced-plate structure as a key fabrication process of micro-mirror array has been researched and a bulk Micro-mechanical technology is used for fabricating the Micro-mirror array. Micro-mirror size is 600 by 200μm, and contains 52 micromirror array with a high fill-factor in excess of 97% have been achieved. The test results show that the micro-mirror have a maximum torsional angle about 1.1 degrees with a 164v driving voltage. In contrast with the traditional Parallel-plate structure, the multi-terraced-plate structure can greatly reduce the driving voltage.Keywords：high fill-factor- 20
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Published：2020-08-12 -
Measuring System of Flexible Electronic Checking Fixture on Robot
Abstract：A new measuring system of flexible electronic checking fixture on industrial robot is proposed to overcome the disadvantages of the real special checking fixture commonly used in industrial production – high cost, poor flexibility and low automation. Vision sensor is fixed on the terminal tool of industrial robot which is taken as flexible automation platform. Teach the robot to run the programmed measuring path to get local result and calibrate the transformation relationship from every local sensor system to global system. Repetitive position error of robot in this process is one important influencing factor to the overall system accuracy. An optical precise measuring method is presented to amend the whole result real-timely that another camera is taken as control camera combined with global control points fixed on the supporting assembly to measure repetitive position error. Result is compared with CAD digital module in computer to realize the virtual flexible checking fixture function. Experimental result shows that the overall three-dimensional root mean square (RMS) error of fourteen space point is 0.101mm. The principle of method is reasonable. It can overcome the limitation of real checking fixture such as high cost, heavy waste and losing accuracy affected by anthropic factor and realize high accuracy, flexibility and automation checking measurement.Keywords：Laser-vision measurement- 34
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Published：2020-08-12 -
Process theory of spherical photoresist spin coating
Abstract：In order to uniform thickness photoresist coating on the concave spherical surface , the coating technology of centrifugal is researched. First, the critical factors that affect the evenness of photosensitive resist and the film forming force are investigated. Then, the centrifugal glue adhesive force during the flow state is analysed with the hydrodynamic theory of the spherical photoresist spin coating down opening. A mathematical model which describes the relationship among the film thickness and centrifuge speed and viscosity of photoresist and time of spin coating is derived. Finally, in order to verify the correctness of the formula , some experiments of photoresist spin coating on the concave sphere of diameter φ120mm, radius 300mm, vector height 12.5mm of K9 glass dome are carried out. The result which has been tested is certificated that the theory is consistent with the actual situation, The paper analyzed the fomula and concluded: when the axis of photoresist pin coating should be disalignment with the main axis of electric engine, uniform film thickness on the inner surface of the entire sphere can be obtained. When the viscosity of 110~190centipoise, the speed of 3000~6000/r.min-1, the uniform film thickness of 0.5μm ~1μm can be get on concave sphere.Keywords：Rotating speed- 37
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Published：2020-08-12 -
Design of an exact constraint micro-motion angle displacement mechanism with two degrees of freedom
Abstract：In order to design a micro-motion angle displacement mechanism for precision engineering, degree of freedom and constraint pattern of 3HSE and 3HSVR angle displacement mechanisms with three screws are analyzed, it shows that the common angle displacement mechanisms designed via three point supports have the uncertainty of the orientation and motion. On this, an exact constraint angle displacement mechanism with double screws is presented, the mechanism is exactly constrained by six point constraints so that the position and orientation are deterministic at the natural state, and at the input state the number of degree of freedom is equal to the number of the input so that the motion is deterministic. The adjusting orientation principle under different inputs is proofed. Finally, the sensitivity is analyzed via the relationship of kinematic geometry. The result indicates that the sensitivity is superior to 0.83μrad. The angle displacement mechanism only has two inputs. The orientation and motion of the mechanism are deterministic and has good stability. It is suitable for the angle adjustment of instruments and optic elements in precision engineering.Keywords：sensitivity- 42
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Published：2020-08-12 -
Burst pressure of capillary burst valve based on glass and PDMS
Abstract：It is important to calculate the burst pressure of capillary burst valve used in a microfluidc system. When the passive valve is limited by a glass flat cover with good hydrophilicity, the experimental results shows that some liquid contact line will pass through the entrance of expansion section on the case of a glass cover, but the valve still have a capability of stopping a liquid flow. The current simulations of capillary burst valve are not exact for the above condition. The Surface Evolver (SE) was successfully used to simulate the burst pressure of the microvalve composed of the glass cover and PDMS microchannels by posing the properly boundary condition and monitoring the variation of the contact angle at the entrance of expansion section. For the microvalves with 25μm depth and the aspect of 2, 4, 8 and 16, the capillary pressures are 0.77, 0.45, 0.33 and 0.24KPa, respectively. The obtained simulate data have agreement with experiment data. The effect of the contact angle is discussed and the simulations show the valve do work until the sum of the contact angle on both the flat cover and the channel wall is greater than 90°.- 50
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Published：2020-08-12 -
Design and Analysis on single station Optical radar integration attitude measurement system
Abstract：Abstract: The use of optical tracking in three dimensional space flight target attitude measurement is the measurement of modern weapon systems the new requirements, the traditional method of multi-station intersection measurement precision optical measuring instruments demanding, real-time data processing very difficult, but also by the optical measuring equipment distribution stations restrictions. Using high-precision optical performance and high-precision angle measuring radar range performance applications ranging radar theodolite methods to install optical radar attitude measurement system set up in order to achieve single-station theodolite target, real-time three-dimensional attitude of Target Solutions , to improve the accuracy of real-time measurement purposes. Choice of single station measurements based on yaw angle, pitch angle and roll angle of the algorithm to determine the system's key technical indicators, analysis of simulated target computing system the role of distance and attitude measurement accuracy, the results show: the role of the simulated target distance less than 60km, real-time three-dimensional attitude measurement error is not greater than the total. On the range precision optical measuring instruments under the conditions of the existing designs using the single radar station photoelectric method of attitude measurement system design goal of three-dimensional attitude measurement flight, not only can improve the accuracy of instruments to measure the real-time, also eliminates the traditional methods of measurement caused by the intersection cloth station limits, improve equipment utilization.Keywords：Design Analysis- 52
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Published：2020-08-12
Micro/Nano technology and fine mechanics
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Global calibration method for CCD based visual inspective system
Abstract：To detect the size distribution of compound fertilizers accurately, an overall calibration method was proposed for the CCD based visual detective system of a particle size analyzer. Firstly, the detection accuracy of the inspective system was analyzed and the light source was controlled in servo to reduce the effect of instability and asymmetry of the light source on the detection accuracy of the visual detective system, Then, an appropriate scanning speed of CCD was determined to insure the real shape of the object to be detected. Finally, based on the theory of the ruled surface, the pixel diameters and pixel coordinates were obtained through measuring the balls with different diameters for several times. The overall calibration of the whole detective system was implemented by using Excel, MIL and other tools to establish mathematical model of ruled surfaces. Experiment results show that the non-uniformity response of the CCD vision inspection system has been significantly improved, and the detection error is within ± 3%. It is simple, intuitive, feasible, and can meet accuracy demand of the particle size analyzer.Keywords：visual detection;ruled surface;CCD;global calibration;particle size analyzer- 66
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Published：2020-08-12 -
Suppression of infrared image background by multiscale hidden Markov model
Abstract：A background suppression method based on multi-scale Hidden Markov Mode (HMT) was proposed to remove the complex background clutter in the detection of dim and small targets. According to difference of distributed characteristics between target and background clutter in infrared image, the shearlet transform based multi-scale HMT was estimated by using the different scale and direction relation of inter-scale and cross-subband coefficients of decomposed images. Finally, the expectation-maximization(EM) algorithm was used to calculate the background, separate dim and small targets and background clutter of infrared image and to implement the suppression of background, and the preservation and enhancement of target signals. Compared with Max Median (MMed) and Local Means Remove (LMR) filter from subject inspection and value index, several groups of experimental results demonstrate that the proposed method can suppress the complicated background in dim and small target images effectively(SCR>=1.6).Keywords：infrared image;target detection;background suppression;Shearlet transform;hidden Markov Model- 63
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Published：2020-08-12 -
A new filtering method of improving quality of grating Moiré fringe
Abstract：A new filtering method to improve the quality of grating Moiré fringe is presented in this paper, named phase-difference filtering.Each field of the 4 field scanning reticle is devided into multi-lines with different phases, which achieves the suppression of high harmonic generations. In this way the quality of Moiré fringe signal is improved. . Firstly the Fourier series expression of Moiré fringe is introduced and various harmonic generations of the Moiré fringe are analysised. Then, the filtering method eliminating the second, third and fourth harmonic generations is illustrated with the designed grating patterns. Finally, the valid of the method to inhibit the high harmonic generations is verified through simulations and experiments. Experimental results indicate that the third harmonic generation of the Moiré fringe signal can be reduced by 4.9% and the accuracy can be improved by 0.5μm with period of 20μm. This method has the benefits of effective, low cost, without increasing the system size and easy-to industrial production.Keywords：high harmonic generations- 52
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Published：2020-08-12 -
The application of Spectral domain optical coherence tomography in oral cavity tissue
Abstract：Objective: Because of the organ exposure in oral cavity, the oral cavity tissues become the optimal object of OCT. Method: Spectral domain optical coherence tomography (SDOCT) is a non-invasive, contact-free and high resolution technology developed by time domain OCT. Spectral domain OCT (SD-OCT) improves the imaging speed, as it can obtain the information of the whole depth without the mechanical scanning which is possible to obtain the real-time and vivo images. By self-designing, the SDOCT set of fiber type has been constructed which is easy to integration; the longitudinal resolution is 7.3μm; lateral resolution is 9.5μm; and the imaging depth can be achieved 3.14 mm in air. The histomorphological features of the salivary glands have been studied based on the set. Result: The OCT images are compared with the pathological sections. The microstructures of the parotid gland have been obtained by the comparisons. Conclusion: The results have indicative effects to the early diagnosis of the oral cavity tissue and the non-harmful examination.Keywords：histopathology- 45
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Published：2020-08-12 -
Study on the Optimization Algorithm for the Bandwidth of the Phase-Locked Loop in OTU
Abstract：Under the consideration of the external input jitter and the internal phase noise, the optimization algorithm of the bandwidth for the PLL(Phase-Locked Loop) of OTU(optical transponder unit) can be deduced and obtained through improving the former calculation and analytical methods. The optimal bandwidth of the PLL can be obtained after analyzing to ensure the clock output of the OTU has a lower jitter noise. And then the optimization algorithm is applied in 2.5Gbit/s and 10Gbit/s of the OTU, the optimal parameters of the PLL and the output jitter value of the regenerator can be acquired by taking the quantitative and qualitative analysis of the loop parameters. The study shows the optimization algorithm is better suitable for the OTU and play an important role in the practical application.Keywords：jitter- 37
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Published：2020-08-12 -
Rapid hand-eye calibration in dual robots system
Abstract：Aiming at hand-eye calibration in dual robots measurement system, a method based on machine vision by calculating target robot flange pose and center coordinate is presented. Move target robot flange to a proper pose to get an image by the camera, extract ellipse contour of the flange in the image, calculate the flange pose and its circle center data according to the camera coordinate system, then use location of the pinhole on the flange to obtain coordinate transformation H1 between camera coordinate system and flange coordinate system. Record coordinate transformations between flange coordinate system and robot base coordinate system separately, marked as H2 and H4, from the robot controllers. The coordinate system transformation H3 between two robots can be derived from single axis movements of robots, then the hand-eye coordinate transformation can be calculated by HCG=H4H3H2H1. Move the target flange to some coplanar poses and get their images, the calibration accuracy can be improved by image fusion. Experimental results indicate that the calibration precision of single image and coplanar poses using image fusion is 0.345° and 0.187° separately. It can satisfy the dual robot system requirements of vision guiding measurement.Keywords：Circle pose- 65
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Published：2020-08-12
Information sciences
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