Laser cleaning is a surface engineering technology which uses the high-energy characteristic of laser to remove attachments on the substrate. It has been gradually promoted in the fields of microelectronics, mould, building, aerospace, and so on. However, as a pillar industry of national economy, there are rare reports on the application of laser cleaning technology in petrochemical industry. In this paper, the cleaning needs and technology status of petrochemical industry are introduced, the existing technology cannot fully meet the new requirements of petrochemical industry development. The development of laser cleaning technology both at home and abroad in recent years is reviewed, the work has provided a theoretical basis and ideal reference for the application of laser cleaning in the petrochemical field. And the application occasions of laser cleaning technology in petrochemical field are analyzed. In addition, the specific research directions and application prospect are pointed out.

When the microLED is in the forward working direction, it is difficult to precisely adjust its voltage to obtain different brightness. Moreover, when the microLED/OLED is turned on, they will be in a closed state for a long time, causing the image display brightness to be deteriorated by the human eye. In order to solve these problems, this paper proposes a dual-frame decentralized fusion scanning strategy to achieve different brightness by adjusting the microLED/OLED on-time. Firstly, the method de-weights the data bits and inserts their on-times into the closed time. Then the data bit weights are double-frame fused after decentralization. Finally, the scanning order of the data bits is redefined. According to the proposed scanning strategy, we designed a scanning controller to drive digital on-silicon microdisplay. The results show that the dual-frame decentralized fusion scan proposed in this paper can accurately adjust the luminance of microLED/OLED and improve the brightness of the image observed by human eyes. Compared with other scanning strategies, the scanning strategy improves the scanning efficiency to 93.75%, the field frequency is increased to 2040 Hz, the scanning clock frequency is 102.36 MHz, and the scanning data bandwidth is reduced. The feasibility of the scan controller is proved by testing at last.

Person re-identification is significant but a challenging task in the computer visual retrieval, which has a wide range of application prospects. Background clutters, arbitrary human pose, and uncontrollable camera angle will greatly hinder person re-identification research. In order to extract more discerning person features, a network architecture based on multi-division attention is proposed in this paper. The network can learn the robust and discriminative person feature representation from the global image and different local images simultaneously, which can effectively improve the recognition of person re-identification tasks. In addition, a novel dual local attention network is designed in the local branch, which is composed of spatial attention and channel attention and can optimize the extraction of local features. Experimental results show that the mean average precision of the network on the Market-1501, DukeMTMC-reID, and CUHK03 datasets reaches 82.94%, 72.17%, and 71.76%, respectively.

Water-jet guided laser (WJGL) machining is a novel processing technology using water beam fibers to guide the laser to machine the work-piece surface. This processing technology has the advantage of almost no micro-cracks, small heat-affected zone, pollution-free, less recast layer, high processing accuracy, parallel cuffing, etc. This work aims to investigate the effect of different WGLM parameters on the micro-morphology of materials and the mechanism between lasers and materials. The experiments for slotting and grooving 316L stainless steel thin samples were used by the WGLM system developed by our research group in this work. The 2D micro-topography after experiments were tested by the Zeiss Vert.A1 metalloscope, and the 3D micro-topography of samples after experiments were tested by the Leica DVM6 optical microscope with the large depth of field & Bruke Contour Elite I white-light interferometer. Experimental results show that a certain width deposition layer can be occurred in the machining region, and the width of deposition layers does not change with the parameter of the machining time and the number of machining times. From the 2D micro-topography of samples, it can be found that the ‘dr’ of slotting samples and the ‘wl’ of grooving samples also do not change with the machining parameters. From the 3D micro-topography of grooving samples, it can be found that the cross-section shape is inverted trapezoid.

Frequency modulated (FM) signal is extensively applied in sonar, radar, laser and emerging optical cross-research, its sparsity is a common basic issue for the sampling, denoising and compression of FM signal. This paper mainly studies the sparsity of FM signal in the fractional Fourier transform (FRFT) domain, and a maximum singular value method (MSVM) is proposed to estimate the compact FRFT domain of FM signal. This method uses the maximum singular value of amplitude spectrum of FM signal to measure the compact domain, and WOA is used to search the compact domain, which effectively improves the shortcomings of the existing methods. Compared with MNM and MACF, this method gives a sparser representation of FM signal in the FRFT domain, which has less number of significant amplitudes. Finally, the primary application of this method in the FM signal filtering is given.

The startup error of fiber optic gyroscope (FOG) in north-seeking is the error caused by the zero-bias drift of FOG caused by drastic change of the temperature in the starting process. The start-up error significantly increases north-seeking error during the cold startup phase compared to the stable phase, which prolongs the effective north-seeking time. Through the analysis of the factors affecting the temperature drift of FOG, the multi-parameter linear model was established by empirical mode decomposition (EMD), autoregressive-moving average (ARMA) modeling and Kalman filtering to realize a temperature drift compensation method applied to FOG north-seeking. The experimental results show that the method can reduce the north-seeking startup error by nearly 80%, so that the startup north-seeking precision is equivalent to the stable phase and the effective north-seeking time is shortened.

For an optic-electro tracking system, an image sensor such as charge-coupled device (CCD) cannot provide target trajectories except for line-of-sight (LOS) error. Thus, it is difficult to achieve direct feedforward control for the tracking loop, which determines the closed-loop performance. An error-based observer (EBO) control of a CCD-based tracking loop is proposed to enhance the tracking performance for an optic-electro tracking system on moving platforms. The EBO control can be plugged into an existing feedback control loop. The closed-loop performance of the CCD-based control system can be improved by optimizing the feedforward filter Q(s). Because this EBO method relies only on the final LOS error, it benefits the control system both in disturbance suppression and target tracking and it can be applied to an optic-electro tracking system in moving platforms as well as in ground platforms. An optimal Q31 filter rather than a low-pass filter is improved for this EBO control. Simulations and experiments show that the tracking performance is effectively enhanced in low frequency compared to traditional control methods.

Automatic identification and location of Mura defect in various screens plays an important role in improving the quality of screens. It is one of the most important technologies that need to be developed urgently. Aiming at the features of low contrast and lack of obvious edge of Mura defect, this paper proposes a method of Mura detection based on image gray curve and its improved method. This improved method is based on the principle of mean filter to smooth the picture and down-sampling. By studying the information about peak and trough of the gray curve on sampling lines, the BP neural network is used to construct an automatic detection and location algorithm for line Mura. The experimental results show that, compared with the existing Mura detection methods, the improved method in this paper can distinguish line Mura defect on the mobile phone screen more accurately and quickly. The accuracy rate is 98.33%, and no parameter needs to be adjusted during the detection process, realizing automatic detection, and positioning of line Mura.

In order to further improve the performance index of second-order Raman fiber amplifier, the main parameters of second-order RFA were analyzed. First, a structural model that can be controlled by optical switches and switched between two modes of traditional second-order and traditional first-order RFA is designed. It is proved through simulation that second-order RFA can increase the system gain and improve noise performance. The gain performance of first-order RFA is optimized. The optimization goal is to reduce the flatness. The particle swarm optimization algorithm is used to optimize the configuration of the wavelength and power of the pump light. After further structural improvement, a second-order RFA with a gain of 24.50 dB and a gain flatness of 0.98 dB were achieved in a 100 nm bandwidth. These results provide a reference for the design of second-order RFA with better performance in the future.

Metal surface plasmon has many novel optical properties and important applications, and it is also a research hotspot. In this paper, a crescent cross (CC) nanostructure composed of a crescent and a cross is studied by the finite element method. New plasmon magnetic mode and multiple Fano resonance can be induced by breaking structure symmetry through changing structure parameters. Meanwhile, by changing the angle between the two rods symmetrically, the figure of merit (FOM) can reach 61. Our structure has important applications in the fields of multi-wavelength sensor, ultra-sensitive biosensor, surface enhanced spectroscopy, and slow light transmission.

We demonstrate a mode-locked Yb-doped fiber laser (YDFL) that enables fiber high-order mode (HOM) oscillation inside the ring cavity, by using a pair of mode selective couplers (MSCs) as an effective mode converter, the optical fiber HOM is obtained. The central wavelength of MSC is located at 1064 nm, which can achieve 80 nm mode conversion bandwidth and 94% high-order mode purity. A mode-locked pulsed fiber laser with a 3 dB spectral width of 7.4 nm, a pulse repetition frequency of 10.9 MHz, and a radio frequency signal-to-noise ratio of 55 dB is obtained, and the slope efficiency of the output power is 2.3%. These results show that the HOM can be directly oscillated by the cascaded MSCs in the fiber laser and participated in the mode-locking process to obtain a pulsed HOM laser.