For the infrared band near 1 550 nm, a transmissive beam deflector based on a dielectric metasurface is proposed. This deflector can achieve a large deflection angle together with a broadband spectrum and high efficiency. The structural design of the deflector is optimized according to the generalized Snells law. It comprises amorphous silicon nanopillars with trapezoidal cross sections that are arranged periodically on a quartz glass substrate. The continuous phase gradient formed by the unique trapezoidal nanopillars in the proposed structure provides superior deflection characteristics compared with those provided by the discrete phase gradient formed by the discrete nanopillars utilized in traditional metasurfaces. The performance of the proposed device is simulated and analyzed with respect to efficiency, deflection angle, wavelength dependence, and incident angle dependence using the finite-difference time-domain method. The performance of this device is tested after its fabrication via processes such as electron beam lithography. The simulations indicate that this deflector realizes a deflection angle as large as 42.8° at 1 550 nm, as well as a transmissivity of 84%, a deflection efficiency of 80%, and an allowance of incident angle between -10° and 5°. Moreover, the deflector exhibits impressive deflection characteristics for wavelengths ranging from 1 350—1 650 nm, with an average transmissivity exceeding 87% and an average deflection efficiency of 81%. Experimental test results show that, at the wavelength of 1 550 nm, the beam deflection angle is nearly 41°, the device transmissivity is approximately 76%, and approximately 35% of the incident light is deflected to the target angle. The proposed device represents a new approach for the design of near-infrared metasurface devices and has application potential in numerous fields.

This paper presents the design for a highly sensitive balloon-borne measurement system based on cavity ringdown spectroscopy (CRDS) in order to analyze the vertical distribution of methane above the Tibetan Plateau. The proposed measurement system uses a digital signal processing (DSP) board to lock the cavity mode, acquire the cavity ringdown signal, scan the laser wavelength, and store data. Calculation of the decay rate, spectral curve fitting, and concentration calculations are all performed via DSP. First, the principle of CRDS and the spectrum calculation algorithm are introduced, including details on the improvement of calculation results by using a fixed Gaussian linewidth for fitting the spectral curve. Second, the cavity ringdown signal and spectral curve of the measurement system were analyzed, yielding a signal-to-noise ratio of approximately 62 dB for the cavity ringdown signal. The measurement system was calibrated in the laboratory by measuring standard gases; the maximum standard deviation of the measured values was 2.2×10-9, and the adjusted R-square between nominal values and the RMS of the measured values was 0.998 7. Finally, a field test was conducted in Lulang, Tibet. The instrument was carried by a tethered balloon, and methane concentrations at altitudes between 3 340 m and 6 000 m above sea level were successfully measured. Different trace gases can be measured by replacing the super mirrors in the optical cavity and using lasers with appropriate wavelengths, while the measurement system can be refined further to measure the abundances of certain isotopes.

Bulk heterojunction polymer solar cells are promising alternatives to fossil energy for energy conversion. The synthesis of new materials, optimization of device structures, and interface engineering are feasible methods to improve the power conversion efficiency of polymer solar cells. In this study, research on interfacial engineering in polymer solar cells is reviewed from three aspects: interfacial materials, interfacial doping, and interfacial modification. Many experiments on interface modification have successfully promoted the generation and transport of carriers. It is proved that interface engineering is of great significance to improve the efficiency of charge extraction, passivate the surface defects, and enhance the conductivity.

Interferometry is an important method to realize high-precision measurements. The key requirement for achieving sub-nanometer resolutions is the interpolation and subdivision of periodic interference signals for hundreds or even thousands of times, through which the problem of resolution effectiveness is introduced. Based on the spiral phase property of the Laguerre-Gauss beam, modified high-precision interferometry was conducted using conjugate vortex beams. The measured linear displacement was linearly converted to the rotation of uniformly arranged petal-like interferograms. Regarding signal processing, to improve the measurement reliability, the multiple of the subsequent signal subdivision is effectively reduced via the subdivision of the spatial angles in interferograms. A high-speed photoelectric detection circuit and low-speed image processing were combined and separately used to count the number of integer cycles and image subdivisions to measure the rotation angle. The experimental test system was constructed using conjugate vortex beams with a topological charge value of 4, and 1°rotation of the interferogram corresponded to a theoretically measured displacement of 0.88 nm. The results of the experiment, which employed a real-time signal acquisition and processing system based on LabVIEW and error analysis, demonstrates that the resolution is better than 0.5 nm under normal laboratory conditions.

As an ideal calibration source, the moon has stable spectral characteristics and light intensity within the dynamic range of the detector. Thus, lunar calibration on-orbit is one of the important means to improve the efficiency of radiometric calibration and monitor the imaging stability of remote sensing satellites. Targeting low earth orbit and high-resolution remote sensing satellites, an on-orbit lunar calibration method, which includes imaging time, satellite attitude, imaging parameters of lunar observation, etc., is proposed in this paper. Lunar observation experiments on a low-orbit optical remote sensing satellite were successfully conducted 15 times in July, 2019, under the conditions of satellite attitude angular velocity of 0.06 (°)/s and integration time of 0.293 8 ms. The lunar phase angle covered the range of -79.872° to 89.236°. The results suggest that the satellite attitude of the actual implementation is in accordance with that of the design. Moreover, the lunar calibration method has high observation efficiency, which takes only 1 500 s and will not affect the normal earth observation mission. Furthermore, the texture of 15 acquired images of the moon has a better distribution hierarchy of image DN value, and the spatial resolution is better than 1.18 km. The calculated lunar irradiance distribution trend is consistent with that of the RObotic Lunar Observatory (ROLO) model published internationally. The experimental results verified the correctness and rationale of the proposed method. Multiple lunar phase angle observation has been realized for the first time in China though the attitude maneuver of a low-orbit remote sensing satellite, which can provide a reliable basis for long-term monitoring of the imaging stability of the senor and accumulating a large amount of lunar calibration data to establish a lunar radiation model independently in China.

To prepare a well-oriented ScAlN piezoelectric film with a high piezoelectric coefficient, several groups of ScAlN films were prepared by pulse-DC reactive magnetron sputtering. The effects of gas ratio, power, substrate temperature, buffer layer, and dope rate were investigated through a control variate method. X-ray diffractometer (XRD), scanning electron microscope (SEM), and piezoelectric coefficient tester were used for characterization. The results show that the film prepared with AlN/Ti/Pt has a lower FWHM in rocking curve (2.38°) compared with the buffer layer of Ti/Pt (2.62°). The principle of scandium doping was briefly discussed. The ScAlN film prepared in this study has a longitude piezoelectric constant d33 of -10.5 pC/N, which is 0.9 times higher than that in pure AlN. XRD patterns and SEM images reveal that the improvement in piezoelectric constant is caused by the distortion of the lattice rather than a transition in the crystal structure.

To improve the low rate of temperature monitoring of medical steam sterilizers, caused by testing technology, a temperature monitoring system based on a fiber Bragg grating (FBG) was designed, and its feasibility, accuracy, and reliability of temperature measurement for the whole sterilization process were studied. First, to meet the related standards for temperature monitoring of medical steam sterilizers, an FBG array sensor was designed using wavelength-division multiplexing technology. Then, the corresponding temperature monitoring system was constructed, and the whole sterilization process was monitored in real time. Finally, the accuracy of the detection system was verified by analyzing the temperature changes with time at each stage of the sterilization process, the sterilization time under the effective sterilization temperature range, and the maximum temperature difference between points under no-load, half-load, and full-load. The monitoring results accurately showed the temperature changing with time during each stage of the sterilization process. The effective sterilization time is 7.8 min for the monitored sterilizer, and the maximum temperature difference of each point in the cavity is within 2 ℃ for no-load and 4.5 ℃ for full-load. The temperature measure range and resolution, time recording accuracy, and data storage capacity of the system met national and industry standards. Moreover, the proposed system possess superior characteristics over traditional systems, displaying the potential for economical multi-point monitoring and the ability to enter the narrow area for monitoring.

This study aimed to achieve precise measurements for spherical grid geometrical features and screen the qualified parts for electron optical design requirements. Thus, the characteristics of the measuring equipment, its accessories, grid size design requirements, and common overproof problems caused by processing were studied. First, the optical measuring machine with a laser-assisted focusing system was selected, owing to its grid measurement features, efficiency, and accuracy. Then, an automatic measurement program was compiled, which automatically turned the coarse zero and orientation to the precise values and completed the automatic measurement of all the spherical grid geometrical features. Subsequently, in view of the ‘big radius, small arc’ measurement difficulty, quantitative analysis and calculations were performed to obtain the formula for the uncertainty of the curvature radius measurement. Finally, the sources of measurement uncertainty were discussed, and the methods for eliminating error sources were analyzed. In a practical application, the automatic and precise measurements of the spherical grid curvature radius, profile of the grids spherical surface, circular grating wire concentricity, radial grating wire circle indexing, grating wire widths, outer diameter and its roundness, and the end surface flatness have been achieved. The measurement duration was approximately two thirds of the traditional method, and the number of measuring points was up to 2 094, which is considerably larger than the hand-operated method.

A high-resolution detection system was established on a beamline to accurately measure the slight broadening of crystal rocking curves, caused by cutting, clamping, adjustment, and other processes. Further, the effect of the configuration of the synchrotron radiation experiment on the rocking curve of a crystal was studied. First, the effects of different experimental configurations on the beam bandwidth and angular divergence were analyzed by producing DuMond diagrams. Using the DuMond diagram results and X-ray crystal dynamics diffraction theory, an empirical formula for the rocking curve width was derived. Moreover, a method to improve the angular resolution of the synchrotron radiation detection system was studied. A high-index surface Si (333) channel-cut crystal and a Si (775) monolithic double-crystal monochromator are used to suppress the bandwidth and angular divergence of the beam and modulate a high-resolution detection beam. Finally, a detection system was built on the X-ray test beamline at the Shanghai Synchrotron Radiation Facility. The rocking curve of the Si (111) crystal was measured by the system, and the measured result verified the empirical formula. The experimental results show that the measured value of the full width at half-maximum for the rocking curve of the Si (111) crystal is 4.79″ at 12.763 keV. This measured value is within 2% of the theoretical value of 4.70″ for dynamical diffraction, allowing small changes in the rocking curves of crystals to be detected.

To reduce the large number of stoma generated inside a conductive circuit during laser sintering, which impede further improvements in conductivity, a single factor test was conducted to study the influence of process parameters on the morphology change of a conductive circuit. Once the sintering characteristics of the conductive circuit were determined, a sintering method with variable parameters was proposed to suppress the formation of stoma. The proposed method first selects the sintering parameters that meet the requirements according to the morphological change of the conductive circuit, then determines the optimal sintering method through the single-factor test method. Finally, the stoma and microstructure of the conductive circuit sintered by the optimal method are detected and the effectiveness of the method is analyzed. The results show that laser power significantly affects the morphology of the conductive circuit; the volume of the conductive circuit shrinks during low-power sintering and expands during high-power sintering. The optimal sintering method, based on the sintering characteristics of the conductive circuit, effectively suppresses the formation of stoma, improving the conductivity by 35.6%. The results of this study, based on a sintering process that yielded a conductive circuit with fewer stoma and increased conductivity, are significant for conductive circuit performance and can confer excellent forming qualities to electronic products.

High-precision microstructure glass optical elements are widely used in several applications, including optical systems, precision measurements, and microfluidic chips. The most revolutionary technique for the production of glass optical elements is the use of array molding technology, which is capable of high precision, net forming, and low-cost manufacturing in addition to being pollution free. This technique is also expected to achieve stable mass production of high-precision microstructure glass elements at low costs. In this paper, the advantages and application requirements of the array molding technology for microstructure glass optical elements are introduced. Moreover, global research developments in the manufacturing of microstructure glass optical elements using array molding technology are summarized. Recent progress includes research on mold material and processing technology, glass material and thermodynamic characteristics, finite element simulation, molding process test in the array molding process, and quality of the microstructure glass element detection technology. Novel achievements and technical problems in the manufacturing process are described, primarily focusing on the die material, coating material, die processing equipment and technology, array molding simulation, and forming technology. Finally, future developments in array molding manufacturing technology for microstructure glass optical elements are considered.

To realize the distributed detection function of a sounding rocket platform and to improve its detection agility and precision, a pneumatic release device with a convenient load module, highly reliable clamping, high release precision, and a continuous wide-range thrust was designed. First, the entire design scheme was designed with the features of trapezoidal separating configuration, a size fine-tuning function, and non-uniform releasing contact areas. Second, an optimized, low-cost detailed design was provided by using the shelf products of thin type cylinders. Then, based on the entire design scheme, a releasing function test of the thin cylinder ground-based prototype was accomplished. Finally, a reference value (5 mm) that is suitable for engineering assembly with the required release precision is obtained. The results indicate that the pneumatic release device can work normally with actual air pressure, and its release precision is better than 0.05°. It can satisfy the requirements of the distributed detection function of sounding rocket platforms, and its release precision can be improved by considering actual different cases.

The traditional control method for a fast-steering mirror driven by a voice coil motor suffers from serious phase lag, which limits the performance. Herein, a perfect tracking controller (PTC) was proposed to solve this problem. First, a discrete state space model of the voice coil-driven fast-steering mirror was established, a multirate sampling system was constructed, and a PTC was designed for long-cycle operations. Second, an internal compensator controller was designed for short-cycle operations based on the discrete-time sliding mode control method. The new method achieves perfect tracking of the voice coil-driven fast-steering mirror and reduces the effects of external disturbances, model uncertainties, and mechanical nonlinearity, thus ensuring the robustness of the system. Experimental results show that the proposed PTC improves bandwidth performance. Compared with the proportional-integral-derivative controller method, the system step response time is reduced by 50% and position error is reduced by 50%. Compared with the disturbance observer and zero phase error tracking controller method, the steady-state error is reduced from 1.5% to 0.05%. Moreover, the proposed method allows the fast-steering mirror driven by a voice coil motor to track sine position commands with an amplitude of 360″; the double-decade bandwidth is up to 375 Hz. The proposed method can effectively improve dynamic performance and expand the system control bandwidth.

To address the issue of the accumulated heading angle drift of low-cost MEMS inertial sensors and the inconvenience of using traditional magnetic field calibration methods, a nine-axis inertial fusion algorithm based on dynamic magnetic field calibration was proposed. First, the relationship between the gyroscope and magnetometer was established by a rotation matrix, and the magnetometer was dynamically calibrated by the extended Kalman filter. Second, trust functions were defined considering the free acceleration and the sudden change in the magnetic field environment of the complementary filter, which improved the PI controller. Finally, the attitude angle of the inertial sensor with high stability was obtained. The experimental results show that, the dynamic calibration of the magnetic field by a gyroscope can effectively address the shortcomings of the traditional ellipsoid fitting algorithm, which requires high calibration data. This method can essentially be used in real time, and users can complete magnetic field calibration without a specific “8” winding action. The complementary filtering algorithm is improved to eliminate the influence of free acceleration on attitude angle calculation. When the sampling rate of the sensor is 100 Hz, the running time is approximately 11 min, the number of rotations is 117, and the drift of the heading angle is 0.42°, which is 14.9° less than that of the commercial IMU module, indicating an improvement on the order of a magnitude. This algorithm has considerable advantages in controlling and reducing the heading drift and meets the requirements of convenient calibration and various applicable scenarios. It has a broad application prospects in the field of low-cost MEMS inertial navigation.

The production efficiency of plastic gears is high, and their batches are large; while the traditional manual inspection is low and the accuracy is poor. To ensure product quality and production efficiency, a rapid sorting and inspection system for plastic gears was developed. The system was combined with a production line and used a conveyor belt for loading, a glass rotary for transmission, and a pneumatic device for sorting. Plastic gear images were captured using an industrial camera, and basic parameters such as the tip diameter, the hole diameter, and the concentricity were measured by a machine vision method; the tolerance ranges were compared, in order to judge the product quality. By using algorithms such as image segmentation, edge extraction, feature extraction, and defect identification, surface defects such as missing teeth, black spots, and burr were inspected. Finally, the system separated good and defective products according to the test results. The system could carry out fast, online, automatic, and non-contact separation and inspection. The test results showed that the measurement repeatability of the system was less than 0005 mm, the inspection speed was greater than 150 piece/min, the defect identification and sorting functions were accurate, and the system could run stably for a long time. Hence, the proposed system can meet the requirements of large-scale, high-efficiency, and high-reliability sorting and inspection at a plastic gear production site.

Existing underwater ultrasonic water-level measurement methods have low accuracy and cannot meet the needs of hydraulic physical model experimental measurements. To solve this problem, herein, the source and magnitude of the error are analyzed. By considering the effect of water sound velocity and transit time on measurement accuracy, an underwater high-precision ultrasonic water-level measurement method is proposed. First, by considering the effect of the gap error of the ultrasonic transducer on the accuracy of sound speed measurement, a gap error calculation method is proposed, and the effect of changes in the water environment on the accuracy of water-level measurement is eliminated in principle. Second, according to the principle of the constant shape of the ultrasonic echo signal, the normalized envelope time difference method is used to detect the ultrasonic transit time, and a discrete numerical calculation algorithm flow is designed to reduce the impact of transit time detection of the signal attenuation characteristics. A theoretical analysis shows that the method can reduce the measurement error of the water level in terms of sound velocity and transit time. To verify the feasibility of the proposed method, an experimental prototype was developed, and a metrological verification experiment was carried out. The experimental results demonstrate that the error is <0.1 mm in the 400 mm range, showing that the proposed method can be widely used in high-precision water-level measurement in hydraulic physical model experiments.

A type of three-degree-of-freedom parallel mechanism with a redundant link that can realize one-dimensional translation and two-dimensional rotation is proposed. A novel wave power generating device is then designed based on this mechanism. The kinematics of a floater in this device are analyzed, and the effects of the shape and size of the floater on wave energy acquisition efficiency are analyzed quantitatively. The inverse displacement formulas of this mechanism are then derived, its velocity and acceleration mapping relations are established, and a kinematics simulation is performed. In addition, the workspace of this mechanism is analyzed, a kinematic performance evaluation index is defined that combines the actual applications of the wave power generating device, and performance index distribution maps in the working space are drawn. The results show that the cylindrical and spherical floats are suitable for sea areas with small and large variation ranges of the wave period, respectively. The working space of the mechanism meets the motion requirements of the float of the wave energy conversion device, and the kinematics character is good. This study provides theoretical foundations for kinematic analysis, structural scale optimization, and prototype development of the mechanism.

A robust Mahalanobis bundle adjustment (RMBA) model was developed to improve the adjustment precision of a laser tracker multi-station measurement. In a traditional bundle adjustment (TBA) model, by introducing the Mahalanobis distance, the adjustment criterion, “minimize the weighted sum of squares of the observed corrections, ” was transformed to “minimize the sum of squares of Mahalanobis distances from the observations to the weighted average.” Gross errors were eliminated in the calculation of the weighted average coordinates, and then, the RMBA model was developed. Observations from four survey stations to 12 control points were simulated using MATLAB. Experimental results show that the RMBA model is better than the TBA model ［22］. and Spatial Analyzer (SA) software. The root mean square (RMS) of the deviation from the calculated coordinates to the simulated coordinates was 0.031 mm. The RMBA model was resistant when a gross error was added to the observed values. The data measurement was carried out in the experimental hall of Shanghai Synchrotron Radiation Facility. The observations from four survey stations to 42 control points, which were distributed over a length of approximately 100 m, were used as an example. The mean square error of the coordinates of SA was 0.05 mm. The RMS of the three-dimensional deviation from the RMBA results to the SA results was 0.07 mm. The RMBA model could resist gross error to some degree. Its coordinate calculation precision was almost equal to that of SA and superior to that of the TBA model and that in ［22］.

To improve the level of integration and maximize the use of on-board resources by considering the size, mass, and power consumption, a set of integrated electronic system based on reconfigurable software is proposed. By using a distributed functional module and a generic processor, high level of integration, less redundancy, and high function density are achieved without reducing reliability. First, a high computing capability is realized using a high-performance processor with a cold backup processor and an external circuit design. The standardized communication bus among the systems helps in decoupling the dedicated circuits and the general computing and control circuits in the electric power system, altitude and orbit control system, and other systems. Computing and control are achieved using reconfigurable modular software that runs in the main processor. Finally, a test prototype is designed and tested. The prototype consumes less than 2 W of power, achieves computing capability of more than 220 Dhrystone million instructions per second, and fits in a single CubeSat sized printed circuit board that weighs less than 0.2 kg, which satisfies the requirements of high reliability, low power consumption, and ability for expansion needed by micro/nanosatellites. By adding different functions through the system bus, this system can also satisfy other satellite requirements.

An autofocusing method, based on the characteristic model of the number of pixels changing with the defocus distance, was proposed to quickly obtain a clear fluorescence image of a micropore digital polymerase chain reaction (PCR) chip and overcome the issue of time-consuming calculation in the traditional method for autofocusing of the microscale array unit. Thereafter, fluorescent images of three microarray digital PCR chips equidistant from each other were selected. The threshold was calculated through an adaptive window. The pixels in the window area with values larger than the threshold were counted. The defocus distance was calculated by substitution in the characteristic function. The defocus direction was determined by the pixel values of the three positions and then focusing was carried out. This method uses only statistics of values larger than the threshold of the 13×13 pixels in the focusing window and completes focusing in only four steps. The focusing results satisfied the requirements of subsequent calculations. Compared with the traditional mountain climbing method, the number of focusing steps was decreased by 51.89% on average upon the implementation of the microarray-type digital PCR chip accurate focusing. The proposed autofocus method overcomes the shortcomings of contemporary algorithms, such as extensive computation and tedious focusing steps, and provides an accurate and rapid focusing method. It minimizes the exposure time of the sample, thereby reducing fluorescence quenching, and provides more original and accurate images for subsequent calculations.

This study aims to address the real-time limitations of image matching and the problem of ghosting in image projection stitching. Hence, a fast and improved scale invariant feature transform (SIFT) image stitching and ghosting optimization algorithm was proposed. First, feature points were classified based on the similarity of the shared information between the images, and then, the SIFT algorithm was used to detect and extract the feature points of similar coincident regions. This approach required the algorithm to spend less time on the useless regions. At the image stitching stage, the projection matrix was calculated by feature points, and rough projection was performed. Thereafter, according to the density of the area where the feature points were located, secondary projection splicing was performed on the dense feature points area by optimal fitting transformation to reduce the ghosting problem. Experiments are performed, and the results demonstrate that compared with the traditional SIFT algorithm, the efficiency of feature point extraction is improved by approximately 58%. Similarly, the comparison by an objective evaluation index show that image stitching improved by approximately 10%.

A three-dimensional porous structure is a common application of the endoscope in the field of medical surgery and industrial inspection. However, the limitations of low endoscopic imaging resolution, weak texture features, and high noise make it difficult to utilize a traditional structure from motion (SFM) algorithm for reconstructing and locating the three-dimensional porous structure. In this study, a three-dimensional porous structure reconstruction method based on low-resolution monocular endoscopic images was proposed. The image enhancement algorithm based on weighted guided filtering is first applied to improve the endoscopic image details. The fast marching method is then used to remove floating impurities, and an outlier detection method is proposed to optimize the results of feature matching. Additionally, the sparse point cloud is obtained by an SFM algorithm. Finally, a method based on template matching and least square fitting is presented to extract the three-dimensional structures of holes. Experimental results indicated that the relative errors in the spacing between holes and their diameters of reconstruction on a porous hemisphere were <10%, and the reconstruction results on the real renal surgery video were consistent with reality. Therefore, the validity, accuracy, and feasibility of the whole reconstruction algorithm flow were verified.

To reduce interference to the grayscale of an image due to the reflective characteristics of the PCBA components in a smartphone, improve the integrity of the edge connection, and reduce the number of false edges, this paper proposes an improvement in the traditional Canny operator to extract the PCBA from smartphone edge information. First, considering the characteristics of filter denoising and gradient retention, the use of improved guide filters with “dynamic” penalty factors instead of Gaussian filters reduces the loss of edge points. Thereafter, the traditional double threshold method is replaced with the nearest neighbor local adaptive threshold, which is used to solve the problem of inaccurate threshold segmentation due to frequent grayscale changes in the dense area of the component and the small difference between the background and the target. Experimental results show that a sliding window of 19 has the best threshold segmentation effect, and the number of false edges is minimized. The image processed by this method has more complete and refined edges, the number of false edges is greatly reduced, and the dense local-component area and edge details are retained, which meets the edge detection accuracy requirements of pixel-level mobile phone PCBAs.文章编号