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Surface quality inspection and control are extremely important for electronic manufacturing. The use of machine vision technology to automatically detect the defects of products has become an indispensable means for better quality control. A machine vision-based surface quality inspection system is usually composed of two processes: image acquisition and automatic defect detection. In this paper, we propose a deep learning-based approach for the defect detection of Copper Clad Laminate (CCL) images acquired from an industrial CCL production line. In the proposed approach, a new convolutional neural network (CNN) that realizes fast defect detection while maintaining high accuracy is designed. Our proposed approach makes four contributions. First, we introduce the depthwise separable convolution to reduce the calculation time. Second, we improve the squeeze-and-excitation block to improve network performance. Third, we introduce the squeeze-and-expand mechanism to reduce the computation cost. Fourth, we employ a smoother activation function (Mish) to allow improved information flow. The proposed network is compared with the benchmark CNNs (including Inception, ResNet and MobileNet). The experimental results show that compared with the benchmark networks, our proposed network has achieved the best results regarding the accuracy and suboptimal results in terms of the speed compared with the benchmark networks. Therefore, our proposed method has been integrated into an industrial CCL production line as a guideline for online defective product rejection.

This work proposes a detailed process of micro/nano-structure surface modification in relation to temperature field. In this paper, a femtosecond laser is used to induce the surface morphology of a silicon substrate. We provide a new method for the fabrication of a micro/nano-cantilever probe by controlling the aspect ratio of the silicon surface morphology. A computational method is used to investigate the mechanical behaviors of early perturbation to late-stage structure. A diffuse interface model is employed to describe the evolution and provide a general framework. The theoretical model of femtosecond laser control surface morphology is verified by the experiments. For systematic study, the model involves the interface energy and kinetics of diffusion. This method provides an effective way to improve the sensitivity of micro/nano-cantilever sensors.

Aiming at the problem of extracting cracks on highway pavement under complex backgrounds such as water stains and rutting marks, the global image processing method is difficult to separate the foreground and the background, and the cracks cannot be extracted correctly. For this situation, this paper proposes a method based on probability statistics. The original image is divided into blocks, and then statistics and comparisons are performed on each image to complete the preliminary positioning of the crack area, and then perform the traditional image on the crack area. After treatment, the crack was finally extracted successfully. The experimental results show that the method proposed in this paper has a good effect and high accuracy for the extraction of pavement cracks with complex backgrounds.

Information extraction from images is a key problem. In this paper, a fast, high-precision, multi-target image processing method based on machine vision is proposed to detect nanoparticles. The proposed methods include the following steps: image pre-processing, feature extraction, and result output. An auxiliary-Calibration plate is used as the auxiliary need to determine the measurement accuracy. Through the analysis and calculation of the characteristic scales of nanoparticles, our results are highly consistent with the experiment, indicating the accuracy of our method and algorithm. From the input test images to the output results, the algorithm only takes less than a second. For the image including more complexed structures, it can also be accurately detected. Furthermore, the algorithm is transferable and extensible, and can be applied in wider image processing fields.

The effect of spatial phase modulation on the propagation of finite-energy Airy beam (FEAB) is investigated. A sinusoidal phase is introduced on a FEAB and the propagation behavior is analyzed in Kerr medium by numerical simulation. The basic idea is to impose a sinusoidal phase modulator on the beam before entering the medium. It is found that optical amplitude, spatial modulation frequency, phase shift and truncated factor have important impact on the propagation behavior. Deflection, soliton-like propagation, beam splitting and periodical oscillation can be easily realized by choosing different values of modulation parameters. These results may found novel applications in beam splitter, modulator and other optical steering application for Airy beams. Keywords: Nonlinear optics, Finite-energy Airy beam, Spatial phase modulation

Catalytic gas sensors are widely used for measuring concentrations of combustible gases to prevent explosive accidents in industrial and domestic environments. The typical structure of the sensitive element of the sensor consists of carrier and catalyst materials, which are in and around a platinum coil. However, the size of the platinum coil is micron-grade and typically has a cylindrical shape. It is extremely difficult to control the amount of carrier and catalyst materials and to fulfill the inner cavity of the coil, which adds to the irreproducibility and uncertainty of the sensor performance. To solve this problem, this paper presents a new method which uses a drop-on-demand droplet generator to add the carrier and catalytic materials into the platinum coil and fabricate the micropellistor. The materials in this article include finely dispersed Al2O3 suspension and platinum palladium (Pd-Pt) catalyst. The size of the micropellistor with carrier material can be controlled by the number of the suspension droplets, while the amount of Pd-Pt catalyst can be controlled by the number of catalyst droplets. A bridge circuit is used to obtain the output signal of the gas sensors. The original signals of the micropellistor at 140 mV and 80 mV remain after aging treatment. The sensitivity and power consumption of the pellistor are 32 mV/% CH4 and 120 mW, respectively.

A resonator with a right-angle conical reflector has been proposed to produce high-power CO2 laser beams. To analyze eigenfields of the right-angle conical reflector resonator, this paper adopts and demonstrates the transfer matrix method. In this paper, the mode-fields and corresponding losses are described as eigenvectors and eigenvalues of a transfer matrix according to the self-reproducing principle of laser field. By solving the transfer matrix for eigenvectors and eigenvalues, we obtain field distributions and losses of the dominant eigenmodes. The calculation results reveal that the right-angle conical reflector resonator could be used for a high-power CO2 laser to achieve low-order modes. However, the beam quality is reduced due to the residual blind-hole, which is in accord with the experimental result.

Coffee-ring structures, which are easy to prepare, have many hotspots for surface-enhanced Raman scattering (SERS). However, the inhomogeneous distribution of hotspots causes very poor SERS detection reproducibility, which strongly restricts their practical applications. In this paper, by combining a coffee-ring structure with the waveguide effect of optical fibers, we propose novel micro-coffee-ring-patterned fiber SERS probes fabricated by a laboratory-developed laser-induced dynamic dip-coating method. The mechanisms of micro-coffee-ring formation on fiber facet are analyzed in detail. With the help of a programmable dip-coater, micro-coffee-ring-patterned fiber SERS probes can be automatically and reproducibly fabricated, and they simultaneously show high sensitivity and good reproducibility in SERS detections. A detection limit lower than 10−8 M in aqueous solvent for thiram and methyl parathion (MP) is achieved, and the relative standard deviation (RSD) of the SERS peaks is less than 6%. In addition, benefiting from numerous hotspots provided by micro-coffee rings, this micro-coffee-ring-patterned fiber SERS probe presents superior performance in in-situ trace detection of target molecules in complex liquid environments. Detection sensitivities of 10−7 M for thiram in lake water and in orange juice and 10−6 M for melamine and tetracycline in liquid milk are achieved.

In recent decades, microfluidics in biological applications have experienced significant growth due to their advantages of small volume, low cost, short reaction time and high throughput. Almost all cross-section shapes of micro-channels in microfluidic chips are rectangular or triangular by the existing chip fabricating technologies, including hot embossing, lithography, etching and injection molding, etc. However, compared with the above micro-channel shapes, the circular one has the advantages in aspects of fluid flow, droplet generating, heat transfer and its replication for blood vessels. This paper presents a T-junction droplet microfluidic chip with circular cross-section micro-channels. The effect of micro-channel wettability, interfacial tension, velocity and flow rate of continuous phase on droplet size are simulated and mechanism of droplets generating process is explored. Comparing with continuous phase viscosity and interfacial tension, flow rate plays a decisive role in determining the droplet size which is in the range of 100–350 [Formula: see text]m according to the simulation result. The Capillary number is affected by the above three parameters and an estimating numerical method for generated droplet size was proposed according to the above simulation results and calculated by Capillary number. The droplets, the sizes of which were in the range of 20–400 [Formula: see text]m, were produced by varying the parameters of water and oil flow rates in the designed T-junction droplet microfluidic chip with circular cross-section micro-channels.

In microfluidic chips, most micro-channel cross-section shapes are rectangular or triangular in existing chip fabricating technologies, including hot embossing, lithography, etching, injection molding, etc. However, compared with the above micro-channel shapes, a circular shape has advantages in aspects of fluid flow, droplet generation, heat transfer and blood vessel replication. This paper presents a sandwich-like microfluidic chip with circular cross-section micro-channels. The sandwich-like structure includes three layers. The top and bottom layers are PDMS material while the middle layer is composed of micron glass capillaries (used as micro-channels) with circular cross-sections. The glass capillaries are made of borosilicate tube by a glass heating process. Sphere shaped paraffin wax is used as a sacrificial material to form micro-channel junctions. To test the functions of the fabricated micro sandwich-like microfluidic chip, a droplet generating experiment was conducted in the T-junction chip. The droplet size can be controlled in the range of 20–400 [Formula: see text]m by varying the water and oil flow rates. This proposed microfluidic chip structure has the advantages of short processing cycle, low cost and small flow resistance.

High performance grid-controlled electron gun is the base of modern high power and broadband traveling-wave-tubes. We have developed a shadow grid electron gun, its perveance can be more than 1.6 micro-perveance. The parameters and diagram of the gun is given in this article. Better tactical performance, better anti-interference performance, good mobility are the important conditions for radar to alive. High power traveling-wave-tubes are the key device of the radar; they need high output power, flexible modulation method, and small permanent magnetic focusing system. Accordingly the electron gun of high power TWT should provide high perveance electron beam and should be shadow grid controlled. This article introduces a shadow grid controlled electron gun, the cathode voltage is 26kV, and the perveance can be up to 1.6 micro perveance. The calculated electron trajectories by the 2D compute program are shown. The affect of the circular wires of the shadow grid and the control grid to the moving of the electrons are taken into account during calculation. The shielding factor due to radial grid wires has also been considered.