最新刊期
期 15 ， 2023
- 摘要：Calibrating the driving voltage of each optical switch in optical switched delay line （OSDL） chips requires a multichannel optical power meter， a programmable multichannel voltage source， and other discrete instruments， which causes the problems of high cost and system complexity when the chip scale increases. In this paper， an automatic calibration and control system is proposed for OSDL chips， which includes the functions of a multichannel optical power meter and a multichannel adjustable voltage source. The power detection range is from -53 to -7.7 dBm， with an error of <0.5 dB. The voltage output range is 0-10 V， and the fluctuations are within ±0.5 mV. A microcontroller unit is used to control all parts of the system and communicate with the computer. When the driving voltages of a 5-bit OSDL chip are calibrated with the proposed system， the measured fluctuations of the transmission spectra of all 32 delay states are approximately 1 dB near 1 560 nm， and the measured delay step is 3.110 9 ps/state， which is consistent with the result of 3.062 0 ps/state obtained via calibration using commercial instruments. The proposed system achieved the same calibration and control effect as the commercial instruments and has the advantages of low cost and easy scalability. It has good application prospects.关键词：microwave photonics;integrated optics;optical switching delay line;optical switch;calibration;automation
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发布时间：2023-08-28 - 摘要：To develop high-performance side-viewing all-fiber lenses applicable to the swept-source optical coherence tomography （SS-OCT） system， the factors influencing the performance of a type of side-viewing all-fiber lens and the sample production methods were studied. First， the graded-index （GRIN） optical model of the side-viewing full-fiber lens with the GRIN fiber was analyzed， and the graded parameters related to the performance of the side-viewing full-fiber lens were obtained. Second， the effect of the length of each component of the four-stage side-viewing lens “SMF+ NCF+ GRIN fiber + Angle prism” on its optical focusing performance was studied， and the appropriate length range of each component was designed. Finally， an ultrasmall side-viewing all-fiber lens with an outer diameter as small as 0.5 mm and a rigid length of 2.75 cm was fabricated. Experimental results show that the working distance （0.52 mm） and spot diameter （26.82 μm） of the lens are consistent with the theoretical analysis results. The lens sample is integrated into the SS-OCT imaging system to obtain clear tomographic images of biological tissues； thus， the performance of the designed lens is verified. The results indicate that the proposed method can be used to optimize the structural parameters of side-viewing all-fiber imaging lenses.关键词：optical coherence tomography;optical fiber lens;GRIN fiber;side-viewing
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发布时间：2023-08-28 - 摘要：Sun glint interference seriously hinders the effective acquisition of object information in the remote sensing field. In this paper， a sun glint suppression method based on polarization information for UAV-borne platform was presented to realize all-weather and all-time detection of underwater military targets in a complex marine background. A light component decoupling model was constructed using the polarization characteristic difference between sun glint and object information light and an unsaturated image set was selected to solve the global polarization information of the scene. Then， the spatial distribution of sun glint polarization state was deduced based on the normalized reflectance of sun glint in a Muller matrix. Further， a source-submarine-detector polarization state transmission model was proposed to estimate the polarization degree of object information light； then， the water attenuation coefficient was used to correct the model according to the physics-based model for passive underwater imaging. Finally， a sun glint suppression method that is applicable to a wavy water surface was realized. The outdoor experimental results show that the region contrast and signal-to-noise ratio of sun glint suppression image are improved by 25.3% and 78.4%， respectively， compared with those of the 90° polarization image. Our method can effectively enhance the characteristics of submarine targets under the interference of sun glint， thus helping our country to better explore the sea.关键词：polarization imaging;strong maritime country;sun glint;clutter suppression;aviation remote sensing
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发布时间：2023-08-28 - 摘要：Phase laser ranging is an important means of absolute ranging and an important guarantee for large-scale precision measurement. One of the most effective ways to improve the precision of phase laser ranging is to increase the laser modulation frequency and use high-performance devices to achieve high-frequency sampling analysis. However， the maximum sampling frequency of high-performance devices is limited. To solve the problem that existing devices have difficulty in the sampling of high modulation frequencies， the feasibility of an undersampling method for phase ranging was analyzed and verified. The advantages of all-phase fast Fourier transform （apFFT） analysis was examined to improve the precision of phase laser detection. Based on this idea， the method of undersampling and apFFT was developed， and a phase detection system for laser phase ranging was constructed. When the modulation frequency is 201 MHz and the undersampling frequency is 100 MHz， the system phase discrimination accuracy is higher than ±0.04°， and the corresponding ranging accuracy is approximately ±0.08 mm. The experimental results show that the phase ranging method based on undersampling and apFFT has the comprehensive advantages of high accuracy and strong anti-interference ability， making it valuable for scientific research and engineering applications.关键词：Phase ranging;Under-sampling;All-phase Fast Fourier Transform;high precision;Phase discrimination system
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发布时间：2023-08-28
Modern Applied Optics
- 摘要：Hot embossing is a promising technology for fabricating high-performance glass micro-optical components at low-cost and in a green manner. However， the efficiency and accuracy of hot embossing are limited by the long heating-cooling cycle time and the low uniformity of temperature distribution， respectively. Therefore， it is necessary to develop a high-temperature rapid uniform heating module to improve the efficiency and accuracy of hot embossing. First， a heating module based on a silicon nitride ceramic heater was designed and fabricated， and a heating test platform was constructed， enabling the real-time monitoring of the temperature distribution of the heating module. Constant-voltage heating tests were repeatedly conducted to demonstrate the reproducibility of the experiments. Subsequently， a numerical simulation model was established for the heating module， and the accuracy of the finite element model was evaluated by comparing the simulated and experimental results under the same process conditions. Numerical simulation and orthogonal tests were performed to optimize the heating module and hence obtain decent uniformity of the temperature distribution and a rapid heating rate. The experimental results indicate that the optimized heating module not only had a rapid heating rate but also a uniform temperature distribution. In the constant-voltage heating tests， the heating rate of the optimized heating module is as high as 363 ℃/min， and the maximum temperature difference is 10.7 ℃， which validates the feasibility of the optimization method. In the controlled heating test， the measured temperature curve is essentially consistent with the set temperature curve， and the temperature fluctuation is within 0.3 ℃. In particular， the temperature difference in the central area of 20 mm×30 mm is approximately 2 ℃. Finally， the optimized rapid heating module and a precision temperature control system were integrated into a high-temperature hot embossing machine， which achieved efficient hot embossing of high-quality N-BK7 glass microstructure arrays.关键词：hot embossing;heating;uniformity of temperature;finite element simulation;orthogonal experiment
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发布时间：2023-08-28 - 摘要：To realize multidimensional wireless power transmission （WPT） of the gastrointestinal capsule robot （CR） and reduce the winding dimension， volume， and heat production of the receiving coil， a novel structure of double dimensional orthogonal rectangular solenoid pair transmitting coil was designed. The direction of the synthesized magnetic field was changed by controlling the currents of different groups of transmitting coils. In addition， the magnetic core was embedded in the transmitting coils of the structure. The distance between the coils was adjusted flexibly according to the size of the detector to reduce the power loss. In this study， a theoretical model of the constructed WPT system was established， and then a finite-element simulation was performed to verify the improvement in the system performance due to the magnetic core. Finally， an experimental platform was set up for testing， and the parameters of the one-dimensional receiving coil were optimized. Furthermore， the feasibility of the system under different transmitting-coil spacings was experimentally verified. The experimental results indicate that when the on-line diameter is 0.05 mm， the optimal number of coils wound is 12， and the optimized number of turns is 120. When the transmitting voltage is 15 V and the transmitting-coil spacing is 300 mm， the minimum receiving power of the center is 1 578 mW， and the energy transmission efficiency is 3.85%. The system can meet the power requirements of the capsule robot with a transmitting-coil spacing in the range of 300-500 mm.关键词：wireless power transmission;capsule robot;transmitting coil;receiving coil
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发布时间：2023-08-28 - 摘要：Inductively coupled plasma （ICP） systems are widely used in the field of anisotropic silicon etching. By depositing a polymer on the lower surface of fluorocarbon plasma， the side-wall etching efficiency can be reduced， and the resulting vertical side walls have a high aspect ratio. ICP can be used for gas-based isotropic etching in the absence of protective gas plasma， and ICP-based isotropic etching has the advantages of a higher silicon etching rate， better controllability， and higher etching selectivity compared with anisotropic etching. In this article， a two-step etching method is proposed for fabricating interconnected honeycomb structures with magnitudes of 2.2×105 to 9.5×105 with different pitches of silicon material over an area of 10 mm2 by controlling etching parameters （gas flow， release period， etching power， internal pressure， and etching temperature of silicon material）. The proposed fabrication method can be used to precisely manufacture honeycomb structures with the desired spacing and homogeneity over a large area. In addition， it has the advantages of simple steps and shorter fabrication cycles. The method has important applications in tissue engineering， cell culture， fluid diffusion， the thermal diffusion of materials， and surface science.关键词：isotropic etching;honeycomb structure;interconnect;etch rate
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发布时间：2023-08-28 - 摘要：Recently， tri-axial fast tool servos， which offer higher cutting flexibility， are being applied to the machining of complex optical surfaces. However， the trajectory tracking performance is significantly affected by various factors， including cross-coupling， high-frequency resonance， and hysteresis nonlinearity. To address these issues， a comprehensive compensation strategy was proposed to achieve high-performance tracking control of spatial trajectories. Specifically， a notch filter was introduced to suppress high-frequency resonance， and feedforward decoupling compensation was employed to weaken the XY planar cross-coupling. Furthermore， a Prandtl-Ishlinskii model was cascaded with a dynamic model to describe the dynamic hysteresis for each axis， and a hysteresis feedforward compensation model was constructed without solving the inversion of the hysteresis model. The sweep test results show that the adopted notch filter can eliminate the high-frequency resonance effectively. The feedforward decoupling compensation further reduces the XY planar cross-coupling by approximately 14 dB. The wideband hysteresis modeling results indicate that the dynamic hysteresis modeling errors of the XY plane actuation and Z-axial actuation are less than ±2.2% and ±1.8%， respectively. With proportional-integral-derivative control used for the main controller， the wideband tracking （10-100 Hz） shows that the maximum tracking error for each axis using the comprehensive compensation strategy is only 25% to 50% that when only inverse dynamic feedforward compensation is used. Furthermore， the tracking results for the spatial trajectory demonstrate the effectiveness of the proposed comprehensive compensation control strategy.关键词：fast tool servo;trajectory tracking control;notch filter;feed-forward decoupling compensation;dynamic hysteresis model
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发布时间：2023-08-28 - 摘要：A large-scale patterned Cu micro-nano structure was prepared via laser ablation technology in liquid. A Si wafer was used as the substrate， which was immersed in an ethanol solution containing Cu2O microparticles and processed by a nanosecond pulsed laser. The effects of the laser power， scanning speed， and number of scans on the Cu micro-nano structure in liquid， the formation mechanism of the patterned Cu micro-nano structure， and the wetting characteristics of the patterned Cu micro-nano structure were analyzed. The results of scanning electron microscopy indicated that with increases in the laser power， scanning speed， and scanning time， the melting of Cu particles in the patterned Cu micro/nanostructure intensified， the particle size of nanoparticles in the center of the laser spot increased， and a micron unit structure was formed at the junction of the laser spot， exhibiting a periodic distribution. Energy-dispersive X-ray spectroscopy confirmed that a small amount of Cu was distributed in the central region of the spot， and a large amount of Cu was concentrated at the junction of the spot. In addition， both the surface roughness and static contact angle of the sample increased with the number of scans. When the number of scans was 6， the average surface roughness， water contact angle， and oil contact angle are （1.3±0.11） μm， （155.2±1.5）°， and （100.0±1.3）°， respectively. The proposed simple and rapid preparation method for large-area patterned Cu micro/nano structures has wide application prospects in the fields of microfluidic chips， water-collection systems， and wastewater treatment.关键词：laser ablation;patterned Cu micro-nano structure;wetting characteristic;binary structure
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发布时间：2023-08-28
Micro/Nano Technology and Fine Mechanics
- 摘要：Break detection is an important part of the diamond wire production process. To address the problems of low sensitivity and lag feedback of existing contact detection， a non-contact wire break detection method is proposed based on machine vision detection of light spots reflected by diamond lines under strong light. Here， the study addresses the limitations of complex spot detection operation and ease of influence from external illumination of traditional image processing by investigating spot target detection on the embedded platform of diamond line spot detection using deep learning. A variety of Yolo-type models were trained and deployed. The problem of poor real-time detection in embedded devices due to the deep network level and large model volume of the original model was also addressed through a lightweight target spot detection model MCA-Yolox based on Yolox. The MobileNetV3 lightweight feature extraction network was used to replace the backbone feature extraction network of the Yolox model， and the model was lightweighted. Then， the enhanced feature extraction network was lightweight using the deep separable convolution and inverted residual structures. Then， combined with the CA attention mechanism， the detection accuracy of the lightweight model was improved. Finally， the improved model was deployed on the embedded platform. The experimental results show that the size and computation amount of the improved model， MCA-Yolox， are reduced to less than 1/3 those of the Yolox model， and compared with Yolox-Tiny and Yolov4-Tiny of the same scale， it has higher detection accuracy. The mAP of the model increased by more than 1%， and the detection speed can reach 30 frames/s after accelerated optimization. In summary， this paper presents a complete industrial detection scheme based on deep learning to detect diamond wire breaks.关键词：machine vision;diamond wire;detection of broken wire;light spot;deep learning;embedded type
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发布时间：2023-08-28 - 摘要：To address the problem of the blurring of the texture details of reconstructed images due to the insufficient utilization of global and local high- and low-frequency spatial information， this paper proposes an image super-resolution reconstruction model based on attention and a wide-activated dense residual network. First， four parallel convolution kernels with different scales are used to fully extract the low-frequency features of the image as the prior information for spatial feature transformation. Second， a wide-activated residual block fused with attention is constructed in the deep feature mapping module， and the low-frequency prior information is used to guide the extraction of the high-frequency features. In addition， the wide-activated residual block extracts deeper feature maps by expanding the number of feature channels before the activation function. As a result， the constructed global and local residual connections not only strengthen the forward propagation of the residual blocks and network features， but also enrich the diversity of the extracted features without increasing the number of parameters. Finally， the feature map is upsampled and reconstructed to obtain a clear high-resolution image. the experimental results show that compared with the LatticeNet model， the peak signal-to-noise ratio of the proposed algorithm is improved by 0.14 dB， and the structural similarity is improved by 0.001 at 4× super resolution on the BSD100 dataset. In addition， the local texture details of the reconstructed image are also clearer in subjective visualization.关键词：residual network;Super-resolution;wide activation;attention mechanism;dense connectivity
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发布时间：2023-08-28 - 摘要：The robustness of convolutional neural network （CNN） models is usually improved by deepening the number of network layers to ensure the accuracy of the results. However， increasing the number of network layers will make the network more complex and occupy more space. This paper proposes an improved CNN modeling method based on human visual features. Through the CNN， the structural features of human vision are fused to improve the robustness of the network against noise without increasing the number of layers or affecting the original accuracy of the model. The experimental results on the Cifar10 dataset show that the classification accuracy of the image inserted into the proposed VVNet is almost the same as that of the original network， and the classification accuracy is improved by approximately 10% in the case of image destruction. Compared with the original deep learning network， the network based on human visual system structure can effectively enhance the robustness of the network while maintaining the original accuracy.关键词：computer vision;machine learning;image recognition;visual cortex
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发布时间：2023-08-28 - 摘要：The detection of naval targets is a key area of research interest in the field of remote sensing image processing and pattern recognition. Moreover， the automatic detection of naval targets is crucial to both civil and military applications. In this study， we discuss and analyze the advantages and disadvantages of typical deep-learning-based target-detection algorithms， compare and summarize them， and summarize state-of-the-art deep-learning-based ship target detection methods. We also provide a detailed introduction to five aspects of state-of-the-art ship target detection methods， including multi-scale detection， multi-angle detection， small target detection， model light-weighting， and large-format wide remote sensing imaging. We also introduce the common evaluation criteria of ship target recognition algorithms and existing ship image datasets， and discuss the current problems faced by ship target detection algorithms using remote sensing images and future development trends in the field.关键词：remote sensing imagery;ship target detection;convolutional neural networks;image dataset
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发布时间：2023-08-28
Information Sciences
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