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Issue 1 ， 2019
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Fast alignment of beam verticality for absolute gravimeters
Abstract：To reduce the influence of beam verticality on the accuracy of gravity measurement for free-fall absolute gravimeters based on optical interferometry, a fast alignment method based on the adjustable deflection of the laser beam by two liquid-filled optical wedges to realize the self-correction of beam verticality was proposed. When the direction of the laser beam deviates from the plumb line, the liquid forms variable optical wedges under the force of gravity due to the nature of the liquid level. The laser Keywords：absolute gravimeter;optical wedge;beam verticality;laser interferometer;self-correction- 108
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Published：2020-08-13 -
Target geo-location based on laser range finder for airborne electro-optical imaging systems
Abstract：As the line of sight (LOS) measurement cannot be obtained accurately for a small-scale, airborne, electro-optical imaging system, a laser range finder (LRF) is proposed based on a target geolocation algorithm. According to target locking and tracking characteristics of an airborne photoelectric detection platform, the same target is measured repeatedly. The distance between the airborne electro-optical imaging system and target is measured by the LRF. Considering the ellipsoidal earth model and global digit Keywords：airborne electro-optical imaging system;laser range finder;target geo-location;extended Kalman filter;error analysis- 163
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Published：2020-08-13 -
Polyimide-coated fiber-optic bundle comprising double clad fibers for endoscopy
Abstract：A miniaturized (< 0.4 mm), low-cost fiber bundle based endoscope suitable for pre-clinical research was presented. The device incorporates a Gradient-Index (GRIN) lens bonded to the proximal end of a fiber-optic image guide. Further, a simplified, low-cost connectorization method was proposed and connectorization for alternative applications was discussed. The fiber bundle was coated with polyimide which was bio-compatible for both long- and short-term implantation. In keeping with common laboratory and Keywords：optical diagnostic imaging;fiber optics;endoscopy;gradient-index lens- 125
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Published：2020-08-13 -
Polyimide-coated fiber-optic bundle comprising double clad fibers for endoscopy
Abstract：A miniaturized (<0.4 mm), low-cost fiber bundle based endoscope suitable for pre-clinical research was presented. The device incorporates a Gradient-Index (GRIN) lens bonded to the proximal end of a fiber-optic image guide. Further, a simplified, low-cost connectorization method was proposed and connectorization for alternative applications was discussed. The fiber bundle was coated with polyimide which was bio-compatible for both long- and short-term implantation. In keeping with common laboratory and clinical procedures， the finished assembly allows for chemical cleaning, disinfection and autoclave sterilization with negligible impact on the overall performance of the device. The performance was evaluated by using standard test targets for white light as well as fluorescent microspheres to verify image quality. The results show that the effects of crosstalk between fibers and autofluroescence have a minimal impact on image quality. The fiber bundle assembly is able to resolve fluorescent samples at cellular resolution without the need for a complex optical path or laser scanning mechanism.Keywords：Endoscopy;Fiber optics;Gradient-index lens;Optical diagnostic imaging- 75
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Published：2020-08-13 -
Co-focus error detection of segmented mirrors
Abstract：Based on the traditional Shack-Hartmann wavefront sensing technology, a co-focus error detection system has been designed for the synthetic aperture system, which is used to detect the tilt error of the segmented primary mirror of the synthetic aperture system. Because of the vibration of the experimental platform and the disturbance of the air flow in the experimental environment, the centroid of mass of the Shack-Hartmann spots array makes irregular jitter which results in the co-focus error detection sys Keywords：optical detection;co-focus error detection;segmented mirrors;synthetic aperture system- 142
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Published：2020-08-13 -
Probe-based multi-view field 3D vision measurement system based on three-dimensional orientation target
Abstract：To meet the shape measurement of a polyhedral or rotary body, whose surface includes shadowed areas, deep holes, or grooves, a probe Multi-View Field (MVF) 3D vision measurement system based on 3D orientation target was proposed. We introduce the structure and principle of the vision measurement system. First, based on close range photogrammetry, six element models of the orientation target were built and the local coordinates of the corners in each model were obtained. Based on the above results, stitching Keywords：3D vision measurement;three-dimensional orientation target;probe;multi-view field;close range photogrammetry;homography matrix- 138
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Published：2020-08-13 -
Efficient continuous-wave MgO∶PPLN optical parametric oscillator with three-mirror linear cavity
Abstract：In order to optimize the output characteristics of continuous-wave singly resonant MgO∶PPLN optical parametric oscillations (OPO), a compact three-mirror linear cavity structure was designed for efficient signal light and idler light outputs. A diode laser end-pumped Nd∶YVO4 crystal laser at 1064 nm was used as the fundamental laser source to derive the OPO in the cavity. Three laser cavities with cavity mirrors chosen from plane mirror or plano-concave mirror were designed for comparison. The simulation results show that the fundamental laser beam could be compressed, and the power density could be improved on the MgO∶PPLN crystal if all three cavity mirrors used the plano-concave mirror (named concave-concave-concave cavity in this paper). The frequency conversion efficiency would be improved for better mode matching between the fundamental cavity and the OPO cavity with the concave-concave-concave cavity. A total output power of 3.92 W and conversion efficiency of 31.6% were obtained at the incident pump power of 12.4 W and grating period of 30.5 μm. A 2.6 W light signal with the center wavelength at 1 549 nm and 1.32 W idler light with center wavelength at 3 394 nm were achieved.Keywords：optical parametric oscillator;mid-infrared laser;MgO:PPLN;quasi-phase-matching;end-pump- 69
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Published：2020-08-13 -
Efficient continuous-wave MgO: PPLN optical parametric oscillator with three-mirror linear cavity
Abstract：In order to optimize the output characteristics of continuous-wave singly resonant MgO: PPLN optical parametric oscillations (OPO), a compact three-mirror linear cavity structure was designed for efficient signal light and idler light outputs. A diode laser end-pumped Nd: YVO4 crystal laser at 1 064 nm was used as the fundamental laser source to derive the OPO in the cavity. Three laser cavities with cavity mirrors chosen from plane mirror or plano-concave mirror were designed for comparison. The simulation Keywords：optical parametric oscillator;mid-infrared laser;MgO: PPLN;quasi-phase-matching;end-pump- 138
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Published：2020-08-13 -
Error-compensation of angular displacement measurement based on posteriori error fitting
Abstract：In the aerospace, military, and industrial fields, which have strict requirements on the volumes of devices, photoelectric encoders require not only a reduction in the size and weight of the outer diameter, but also improvements in the measurement accuracy. In this study, an error compensation method for photoelectric encoders was investigated. The error model parameters were determined based on a posteriori error-fitting method, and then depth error compensation was performed for a small photoelectric enco Keywords：photoelectric encoder;posteriori error fitting;error-compensation;long period error;short period error- 115
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Published：2020-08-13
Modern Applied Optics
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Attitude control in multi-satellite cooperative observations for distributed remote sensing
Abstract：This paper focuses on the cooperative observation problem in multiple spacecrafts. We first establish the desired attitude from the sun orientation to the target starting from the reference spacecraft. A proportional-differential (PD) controller is designed based on attitude and angular velocity deviations. Further, the Lyapunov theorem of the closed-loop system is introduced to prove the stability. Next, we establish the desired attitude for the follower spacecraft. To match the target positions in the image plane for the reference and follower spacecraft, a PD controller is proposed based on the difference of attitude between the reference and follower spacecraft. In addition, the Lyapunov stability of the closed-loop system is demonstrated. Finally, the simulation results show that the attitude control error between the reference and follower spacecraft is less than 0.01°, and the control accuracy satisfies the requirements of distributed remote sensing tasks.Keywords：micro-nano satellite;distributed remote sensing;collaborative observation;attitude control- 131
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Published：2020-08-13 -
Preparation and application of semi-fixed abrasive lapping plates with cecullar structure
Abstract：In addition to a good surface quality, surface shape accuracy is also necessary. However, it is difficult to guarantee the surface shape accuracy of the substrate during lapping with the general semi-fixed lapping owing to the lapping plate's soft surface. Therefore, we propose a new design and preparation method of semi-fixed lapping plate with cellular structure. The cellular structure made of epoxy resin is designed to play a supporting role, which can reduce the deformation of the lapping plate and impr Keywords：ultra-precision machining;lapping;semi-fixed abrasive lapping plate;sapphire substrate;surface shape accuracy- 114
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Published：2020-08-13 -
Review of measurement methods for areal surface roughness
Abstract：The measurement of surface roughness is a crucial tool for characterizing engineering surfaces. After more than 20 years of development, areal surface roughness has become a key factor that reflects the characteristics of engineering surfaces. This study includes summaries and comparisons of the characteristics of areal surface roughness, contact and non-contact measurement methods, and nanometer-scale surface roughness analysis methods. The applications and limitations of existing methods are also analyzed, and the direction for future development is presented.Keywords：areal surface roughness;measurement methods;contact measurement;non-contact measurement;nanometer-scale surface roughness analysis- 160
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Published：2020-08-13 -
Method for increasing duty cycle of photoresist grating by hot pressing and its application
Abstract：Holographic lithography combined with anisotropic wet etching of monocrystalline silicon is an important method for the fabrication of high-aspect-ratio silicon gratings. However, increasing the duty cycle of photoresist grating to improve the fabrication process tolerance and grating quality is a major problem. We present a method for increasing the duty cycle of photoresist grating by hot pressing. The principle of this method is to broaden the width of photoresist grating lines directly by heating and pr Keywords：silicon grating;high aspect ratio;photoresist grating;duty cycle;hot pressing- 93
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Published：2020-08-13 -
Microfluidic inertial switch with high threshold and long pulse-width response
Abstract：In order to realize the power management of intelligent weapons, a microfluidic inertial switch with a high threshold and long pulse width response was proposed for two typical acceleration signals of launch and drop. The switch is mainly composed of a circular microchannel and a three-stage capillary valve that has the ability to identify the two typical accelerations and can be reliably connected under the action of the normal launching acceleration. First, the design concept of the switch was introduced, Keywords：microfluidic inertial switch;capillary valve;high threshold;long pulse-width- 109
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Published：2020-08-13 -
Calibration of circular division artifacts using a self-developed angle comparator
Abstract：In order to achieve high-precision calibration of circular division artifacts with sub-arcsecond level, an angular measuring system based on a high-precision angle comparator and an autocollimator was established. A nonphysical circular indexing error detection method was studied, and the scheme to control measurement error was investigated. Firstly, the structure of self-developed angle comparator based on vacuum preloaded air bearings and ultrasonic motors, and the construction of the whole measurement sy Keywords：angle comparator;angle calibration;dividing error;error analysis;uncertainty evaluation- 88
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Published：2020-08-13 -
Friction modeling and compensation of precision position system
Abstract：To improve the positioning accuracy of a precise positioning system driven by a linear motor, the optimized Stribeck friction model was established that compensates for the main factors affecting the positioning accuracy of friction. First, the traditional Stribeck friction model was optimized. Second, the improved least square algorithm was used to identify the model parameters. Third, the friction model compensation algorithm was simulated and compared with the disturbance observer compensation algorithm. Keywords：driving control;Stribeck friction model;parameter identification;friction compensation- 101
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Published：2020-08-13 -
Fabrication of two-sided integrated microstructure element with high aspect ratio and without film substrate
Abstract：Two-sided integrated microstructure elements are increasingly used in the fields of integrated optical imaging and beam shaping. Aimed at resolving the difficulties of fabricating two-sided integrated microstructure elements with integral materials and high aspect ratio structures, a new method was proposed that was an improved ultraviolet imprint technology for fabricating two-sided integrated microstructure elements with high aspect ratios and without a film substrate. By applying this method, integrated Keywords：two-sided integrated;without film substrate;high aspect ratio;ultraviolet imprint- 85
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Published：2020-08-13 -
Optimization of die bond process parameters of MEMS thermopile chip
Abstract：The die-bonding process is one of the key steps to ensure accurate temperature measurement by MEMS thermopile sensors. However, there remains no effective method to accurately optimize the process parameters of MEMS thermopile die-bonding. In this paper, the working principle of the thermopile sensor was introduced, and the requirements of the die-bonding process parameters-thickness and fillet height were proposed. Guided by the die-bonding process requirements, the influence of the pressure parameters on Keywords：Micro Electro Mechanical System(MEMS) thermopile chip;temperature detection;pressure parameters;dispensing height;patch height- 164
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Published：2020-08-13 -
Fabrication of micro-lens array in large-size drum roller by slow tool servo diamond forming turning
Abstract：In order to realize the high-efficiency and high-precision fabrication of micro-lens array in a large-sized drum lathe, a study on tool path fitting and servo parameter optimization for micro-lens machining with slow tool servo was presented theoretically and experimentally in this paper. The original trajectory characteristics of the micro-lens array were analyzed first, and the chatter marks on the micro-lens surface were caused by sharp points at the original machining trajectory. Secondly, a method was Keywords：micro-lens;trajectory optimization;slow tool servo;roller mold;ultra-precision machining- 101
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Published：2020-08-13 -
Temperature compensation and noise suppression for magnetostrictive liquid level sensor using double detection coils
Abstract：To correct the torsional wave velocity, compensate for the effect of temperature, suppress the pulse current noise, and improve the signal-to-noise ratio of the output signal, a double detection coil structure was designed for a magnetostrictive liquid level sensor. A mathematical model of the torsional wave velocity and temperature was derived, and the relationship between them obtained. The temperature affected the measurement results and the amplitude of pulse current was seen to be larger; these issues Keywords：magnetostriction;liquid level sensor;double detection coils;noise suppression;temperature compensation- 99
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Published：2020-08-13 -
Surface polishing of CVD diamond coating by femtosecond laser
Abstract：In this study, the effects of femtosecond laser power, repetitive frequency, and scanning speed on diamond roughness were examined for the purpose of diamond coating surface Ra improvements. The morphology and roughness of fs-laser polished regions were analyzed with white-light interferometry. The experimental results showed that the diamond coating roughness decreased if the laser power decreased, and when the laser power was less than 100 mW, the roughness increased slightly with the reduced power. The l Keywords：femtosecond laser;diamond coating;roughness;compactness- 183
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Published：2020-08-13 -
Signal fusion of silicon micro-gyroscope array of micro/nano-sate
Abstract：A model was established and an optimal data fusion algorithm was designed to realize the online dynamic data fusion of multi-gyroscopes. The data fusion system performance was compared by building a test system. First, a multi-gyros measurement model was established, then the Kalman method was used to estimate the covariance matrix based on the signal fusion model. There was no matrix inversion during this process. The filtering process, applicable to time varying signals, was utilized. Finally, the effectiveness of the algorithm was verified by an online test system using six MEMS gyros. Experimental results indicate that the signal error is reduced to 1/15. In addition, the accuracy is improved one level and reduced to 1/4, and the computation is reduced to 1/3. A system with this new signal fusion algorithm will show improved accuracy and performance, extending the application range of the micro-nano satellite.Keywords：Micro Electro Mechanical System(MEMS) gyroscope;data fusion;process in real time;time-varying signal- 105
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Published：2020-08-13
Micro/Nano Technology and Fine Mechanics
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Color-line and dark channel based dehazing for remote sensing images
Abstract：A color-line and dark channel based dehazing algorithm was proposed to solve the problem of image contrast decreasing caused by haze in remote sensing images. In view of the deficiencies in the color-line a priori, a least squares based transmittance optimization method was proposed. In order to obtain a more accurate transmittance distribution, the transmissivity maps estimated by the color-line prior and the dark channel prior are fused by weight which is calculated by their credibility. A gradient regula Keywords：image dehazing;color-line prior;dark channel prior;remote sensing images;least squares- 145
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Published：2020-08-13 -
Efficient coding method for deep space detection Bayer pattern image
Abstract：Based on the JPEG2000 compression framework, an RBCR compression algorithm for Bayer remote sensing images with high quality was proposed in this study. In this algorithm, the color components of the Bayer image were separated, and the processing unit subgraphs were obtained. Each subgraph undergoes a 1×4 integer discrete cosine transform, so the correlation of the four color component space domain in Bayer images was reduced. The JPEG2000 algorithm was used to perform the wavelet transform, Tier1 coding, M Keywords：image compression;Bayer pattern image;JPEG2000;deep space exploration- 170
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Published：2020-08-13 -
Blind sidewalk image location based on machine learning recognition and marked watershed segmentation
Abstract：VTA (Visual Travel Aids) are devices used for addressing traveling difficulties of visually impaired people. To develop VTA for guiding visually impaired people to blind sidewalks, a method for blind sidewalk image location was presented based on machine learning recognition and a marked watershed algorithm. The algorithm located blind sidewalks by combining offline training with online recognition and segmentation. First, a blind sidewalk image was pretreated by converting an original image from a camera g Keywords：blind sidewalk image location;perspective transformation;image recognition;image segmentation- 158
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Published：2020-08-13 -
Implementation and performance analysis of optical flow based motion estimation on FPGA
Abstract：Optical flow estimation theory has been proposed in the field of machine vision for many years, but the high computational complexity of the algorithm limits its application in the industrial field. To meet the real-time requirements, a method was realized by FPGA in this study. To improve the accuracy of the algorithm and reduce the consumption of hardware resources, the Lucas and Kanade optical flow calculation method was improved. First, a two-level optical flow computation framework was designed to impr Keywords：two levels optical flow;improved L&K algorithm;real time;Field-Programmable Gate Array(FPGA)- 122
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Published：2020-08-13 -
Point-line-surface gradual surface reconstruction emphasizing sharp feature
Abstract：To overcome the shortcomings of reconstructing sharp features of the point cloud model in current surface reconstruction algorithms, a gradual point-line-surface reconstruction method emphasizing the sharp features was proposed. First, the accurate vectors of the point cloud were calculated using principal component analysis along with k-neighbors iterative weighting according to spatial distance, normal deviation, and surface variation. Second, based on the principle that feature points were present on the Keywords：surface reconstruction;vector calculation;sharp feature;feature extraction;point cloud- 100
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Published：2020-08-13 -
New calibration method of line structured light vision system and application for vibration measurement and control
Abstract：Laser vision is a widely used measurement method in industrial detection, and its calibration is the key in developing visual sensing systems. Thus, a new calibration method of the structured light vision system was proposed. Zhang's calibration method was introduced to accomplish camera calibration. Then, the feature of the laser stripe on the calibration board was extracted, and the calibration of the structured light plane was carried out after processing, based on the collinear condition of three planes Keywords：laser vision;system calibration;vibration measurement and control;nonlinear control- 157
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Published：2020-08-13 -
Adaptive tracking method with fractional differential edge feature
Abstract：To enhance the anti-jamming ability with respect to the background and the illumination variation, an improved tracking method based on the fractional differential edge feature was proposed. The R-L fractional differential edge detection operator and Laplacian edge detection operator were fused to construct a hybrid edge detection operator that could enhance the high and middle frequency information and hold the low frequency information nonlinearly. The hybrid edge detection operator was used to detect the Keywords：fractional differential;edge detection;adaptive fusion;camshift- 109
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Published：2020-08-13 -
Adaptive tracking method with fractional differential edge feature
Abstract：To enhance the anti-jamming ability with respect to the background and the illumination variation, an improved tracking method based on the fractional differential edge feature was proposed. The R-L fractional differential edge detection operator and Laplacian edge detection operator were fused to construct a hybrid edge detection operator that could enhance the high and middle frequency information and hold the low frequency information nonlinearly. The hybrid edge detection operator was used to detect the edge information of the target template and the tracking scene. The hue histogram and edge histogram of the target were separately modeled. According to the dynamic information of the background, the back-projection image could be modeled by adaptively fusing the back-projection probability values, which can be separately obtained based on the two histograms to suppress the interfering information from the background. Experiments show that the hybrid edge detection operator can enhance the signal-to-noise ratio of the edge image and improve the quality of the edge image. Furthermore, the tracking time of the tracking method based on the adaptive fusion of the edge feature and hue feature is less than 20 ms, which can meet the real-time requirements of tracking systems. The tracking method can be applied to effectively track the target in an environment with varying illumination in a background similar to the target.Keywords：fractional differential;edge detection;adaptive fusion;camshift- 60
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Published：2020-08-13 -
Image inpainting using gradient features and color consistency
Abstract：In existing exemplar-based algorithms, the confidence value tends to reach zero rapidly, filling order is unstable, and mismatch can easily occur easily. To address these problems, an image inpainting algorithm using gradient features and color consistency was proposed. To obtain a more stable filling order, mean gradient was introduced to represent the change characteristics of an image structure and texture. Mean gradient was also applied to calculate the priority to ensure that the structure was preferen Keywords：gradient features;S-shaped function;color consistency;image inpainting- 110
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Published：2020-08-13 -
Distributed target tracking based on adaptive consensus UKF
Abstract：As the traditional distributed methods of target tracking may suffer from performance degradation owing to mismatch between the noise distributions assumed as a priori and the actual ones, a distributed target tracking method was proposed based on adaptive consensus unscented Kalman filter to improve the accuracy and robustness of the tracking results. More specifically, at each time step, a distributed UKF (DUK) would be implemented to obtain the estimations of the moving target. Next, an online fault-dete Keywords：distributed tracking;camera sensor networks;adaptive filter;uncertain noise;nonlinear estimation- 81
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Published：2020-08-13
Information Sciences
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