Quantum Dots (QDs) are zero-dimensional nanomaterials with dimensions less than or close to the exciton Bohr radius. With the development of nanotechnology, metal sulfide QDs has attracted wide attention due to their unique optical, electrical and magnetic properties, which can be classified into transition metal-disulfide QDs (TMD QDs), II-VI QDs and IV-VI QDs. The ultrasonic method for the preparation of QDs has the advantages of high efficiency, environmental protection, easy control and scalability, and has gradually become one of the important techniques for the preparation of metal sulfide QDs. Metal sulfide QDs have excellent optoelectronic properties that are different from those of traditional bulk materials, and their superior and unique properties have led to in-depth research and applications in more fields in recent years, such as optoelectronic devices, bio-imaging, and photocatalysis. In this paper, an overview of the preparation of different metal sulfide QDs by ultrasonication is reviewed, and their properties and applications are summarized and concluded. Finally, an outlook on the preparation of metal sulfide quantum dots by ultrasonication is given.

The movable ultra-stable optical cavity can reduce the influence of environmental vibration on laser stability, and suitable for transportation conditions with high vibration intensity. This paper demonstrates an optical resonator made of ultra-low expansion coefficient glass, and the frequency stability of the laser locking to the movable ultra-stable cavity is tested. The mechanical design of the struts fixed inside the metal heat shielding provides good stability and mobility. In this paper, the laser linewidth locking to the super-stable cavity is measured using short-delay heterodyne interferometry and its stability is tested with the help of a vibration platform. It is found that the laser linewidth is lineally dependent on the vibration frequency and gradually increases to a saturated valued with the increase of vibration acceleration. The laser line width can be restored to the value in the absence of vibration when the vibration is removed, confirming the high stability of the super-stable cavity.

The seed-injected terahertz wave parametric production source (is-TPG) is based on stimulated electromagnetic dipole scattering in nonlinear crystals, and has advantages of narrow line width, good coherence, room-temperature operation, and tunability. In this paper, the tuning range, output energy, threshold, and other aspects of continuous/pulsed seed-injected terahertz wave parametric generation source (is/ips-TPG) are investigated based on a 5% molar percentage magnesium oxide doped lithium niobate crystal (MgO∶CLN) of the same composition. Compared to the is-TPG system, the tuning range of the ips-TPG system is expanded by approximately 80%. The 3 dB bandwidths of the is-TPG system and the ips-TPG system are 1 THz and 1.41 THz, respectively, accounting for 51% and 39% of their respective tuning ranges. The ips-TPG system extends the range of the 3dB bandwidth by 41% compared to the is-TPG system. At similar average power densities, ips-TPG produces a stronger THz wave output with a maximum conversion efficiency of 1.01 × 10-5 due to its higher peak power density lowering the threshold. The injection of different forms of seed light has a significant impact on the terahertz wave parametric radiation sources. The experimental results show that the output characteristics of the ips-TPG system are more prominent and have higher value in practical applications. The paper concludes with an analysis and outlook of its future development.

To address the issues of redundancy in point cloud data, prone to mis-matched point pairs, and low alignment accuracy during the process of point cloud registration, a method that integrating supervoxels and geometric features is proposed in this paper. Firstly, key points are extracted using a combination of supervoxels and normal vector information. Subsequently, during the coarse registration phase, feature descriptions are generated using the Fast Point Feature Histograms (FPFH) method, and then initial correspondences are established based on the feature description using a bidirectional nearest neighbor ratio approach, and the correspondences are optimized using a normal vector angle strategy and the Random Sample Consensus (RASAC) algorithm to acquire a robust initial pose. Finally, in the fine registration phase, an enhanced Iterative Closest Point (ICP) algorithm is used based on the initial pose. By performing alignment experiments on the Stanford dataset, it is verified that the proposed algorithm has better robustness and can accomplish point cloud alignment efficiently and accurately.

Aiming at the problem of defective point cloud of power equipment components due to limited scanning range of LiDAR and mutual occlusion of power equipment components in power scenario, a power equipment component LiDAR point cloud completion network Power Point Cloud Complete Net (PPC-Net) based on point feature transform is proposed in this paper. A multi-scale feature fusion encoder is used to extract global and local features of defective point clouds at different scales to avoid the problem of losing detailed features of power equipment components caused by multi-dimensional mapping, and EdgeConv is used to enhance the extraction of neighborhood information from point clouds. Then, the DT module is proposed to integrate feature transfer from parent to child points during the generation stage of fine and complete point clouds in order to preserve the local features of the generated point cloud. Next, a smooth optimization module is designed to output a complete point cloud of power equipment components with uniform distribution and smooth surface through three-level smooth sampling algorithm. Experiments on the self-built power equipment component point cloud dataset ELE and the public dataset PCN show that PPC-Net has a good completion effect on defective power equipment component point clouds and good generalization on the general shape point clouds.

Aiming at the effect of turbulent distortion on the optical field, a new method to simulate the atmospheric turbulence effect of laser transmission is proposed, which realizes the joint simulation of the atmospheric turbulence effect of laser transmission in two dimensions, the amplitude domain and the phase domain, by using the statistical properties of the atmospheric turbulence effect, and the method is applicable to weak, moderate and strong turbulence cases. Based on the two statistical models that can describe the optical field amplitude aberration under different turbulence intensities, the stochastic differentiation method is used to obtain the optical wave amplitude change sequence, and the simulation results of the optical wave amplitude change sequence match well with the theoretical calculations under different turbulence intensities, and the fitting coefficients are all greater than 0.9767. A power spectrum inversion method based on low-frequency harmonic compensation is utilized to generate a time-varying phase screen using a third-order Bessel function stochastic curve design to simulate phase aberrations in atmospheric turbulence effects. Under different turbulence intensities, a Gaussian beam is used as the light source, and the simulation results show that the simulated effects of the constructed complex-domain simulation model of atmospheric turbulence effects coincide with the actual atmospheric turbulence aberration process through the normalized statistics of the intensity of the received spot during the moving process of the time-varying phase screen.

In this paper, a data transmission method based on the combination of the characteristics of the angular momentum of the vortex optical orbit and octal data encoding is proposed. The principle is to encode the transmitted data in octal and map each bit into different sizes of topological charges, use orbital angular momentum keying method to obtain the corresponding topological charge of the vortex light, and utilize the double amplitude grating to detect the topological charge so as to obtain the corresponding encoded data and finally carry out the reverse decoding. The simulation results show that compared with conventional binary optical transmission, vortex optical octet data transmission has a larger channel capacity. Finally, the actual scroll light grid image is obtained and analyzed through the concrete experiment, and the feasibility of encrypted transmission of scroll light 8-bit data is verified.

Automatic welding of saddle-shaped welds has the problems of difficult identification and localization of the weld seam, and difficult planning of welding torch posture. In order to realize the automatic welding of saddle-shaped welds, a saddle weld identification and planning method based on point cloudis proposed using the actual assembly of pipe cross structures as the research object. This method utilizes tight coupling constraints between the normal vector and spatial distance to extract the key pointsaccording to the spatial semantic features. And the key points are approximated by three-times cubic B-spline curvesto obtain the final spatial welding curve. Experiments show that the maximum error of the extracted weld trajectory compared with the real trajectory is 0.68 mm, and the maximum root mean square error is 0.29. The method has high accuracy and robustness, which can meet the needs of practical welding. The practicality of this method is not only limited to saddle-shaped weld seams, but also can deal with other weld seams with curvilinear variations.

In order toinvestigate the mechanism of top-hat laser cleaning of carbon fiber reinforced composite (CFRP), considering the significant differences in the absorption and reflection characteristics of the components of CFRP, the laser load is layered to the meso-finite element model of CFRP. The dual effect of thermal ablation and thermal stress is introduced to restore the morphology of single-pulse flat-top laser cleaning at different energy densities, and to complete the experimental validation. The results show that the layered application of laser load can effectively improve the simulation accuracy compared with the traditional surface loading mode, and the dual criterion of thermal ablation-thermal stress can further improve the morphology reduction effect. The long-axis accuracy of the simulated topography of this model is not less than 96.64%, and the area accuracy reaches 80.00%. Therefore, the instantaneous temperature field distribution of high-precision models can guide the actual process of laser cleaning of CFRP surface resin.

CO as an important intermediate or emission substance generated in industries such as thermal power, metallurgy, and chemical engineering, has the characteristics of flammability and high toxicity. High-precision online detection of CO is of great significance for improving boiler combustion safety and achieving carbon reduction. In this paper, tunable diode laser absorption spectroscopy (TDLAS) and Herriott multiple reflection cell are used to achieve high-precision online measurement of CO concentration in the order of 10-6(L/L), with a detection limit of 0.35 L/L. In this basis, the measurement system is used to conduct experiments on the catalytic conversion performance of CO. And the effects of catalyst content and CO concentration on catalytic reactions are explored. The experimental results reveal the variation of CO catalytic conversion efficiency with catalyst content at room temperature and pressure, with a CO concentration of 10~80 L/L, the higher the catalyst content, the higher the CO conversion efficiency. The experimental results can provide a method for removing CO from the dilution gas when measuring CO concentration using dilution sampling method, which ensures the accurate measurement of trace CO concentration.

In order to meet the design requirements of high angular resolution and miniaturization design of laser alarm system. Based on the embedded system development process, the architecture of MicroBlaze softcore processor was studied, and a minimum laser signal processing system based on MicroBlaze softcore was designed and implemented. The design uses MicroBlaze softcore to build a microprocessor platform, and other peripheral IP cores to complete the design of programmable system-on-chip (SOPC). The design of monolithic integrted processing enables the signal flow to occur inside a chip, which greatly improves the data operation speed and the real-time data interaction. The experimental results show that the system can well realize the acquisition and processing of laser signals, and the communication results with the serial port of external devices meet expectations.

In this paper, the reflow soldering process without flux for Ge window of infrared detectors is investigated, and soldering tests on Ge windows and Kovar alloys with different plating systems are conducted using In solder pieces in a reducing atmosphere. Through the analysis of weldappearance, vacuum leak rate, X-ray NDT, and reliability test of window components soldered under different plating systems, it is shown that gold plating on the soldering surface of Ge windows and Kovar alloys can be used to prepare window components that meet the requirements of sealing and environmental adaptability under reflow soldering in a reducing atmosphere.

In this paper, the differences in installed performance between early domestic medium-wave 320 × 256 infrared focal plane detector components and their foreign counterparts are analyzed. Three experimental methods are employed to test the photoelectric performance of detector components at home and abroad. By analyzing the photoelectric conversion and structure of the detector components, it is determined that the reflection of stray light inside the cold screen is the reason for the difference in the test results, and the blackened layer on the inner surface of the cold screen and the form of its structure are key to the practical application of the component. The improved structure of the cold screen effectively improves the practical application performance of domestic detector modules.

In order to optimize the imaging parameters of infrared remote sensing cameras, a comprehensive evaluation index of signal-to-noise ratio dynamic range product camera performance is proposed in this paper for the first time. A noise voltage model for infrared remote sensing cameras is established and in-depth analysis of the impact of noise is conducted. When the constant noise voltage is much greater than the time-varying noise voltage, the noise voltage model can be approximately simplified into a linear model. Furthermore, the influence of integrating capacitance and integrating time on signal-to-noise ratio and dynamic range is modeled and analyzed, and for the first time, the signal-to-noise ratio dynamic range product is proposed as an indicator for camera performance evaluation. The signal-to-noise ratio dynamic range product increases synchronously with the integration time, with a faster growth rate when the integration time is smaller, and a rapid decrease in growth rate when the integration time is larger. The signal-to-noise ratio dynamic range product increases first and then decreases with the increase of the integral capacitance, and there is an extreme value. The research results play an important role in the parameter optimization design of infrared remote sensing cameras.

Aiming at the problem of non-dispersive infrared CO2 sensor are susceptible to temperature, a new method of double semi ellipsoidal and double channel gas absorption chamber and generalized gaussian radial basis function neural network for temperature compensation is proposed in this paper. Firstly, the right focus of the semi ellipsoidal long axis coincides with the left focus of the right semi ellipsoidal long axis in the double semi ellipsoidal and double channel gas absorption chamber structure, the infrared light source is located at the overlap of the left and right semi ellipsoidal long axes, and the detector is located at another focus of the semi ellipsoidal long axis, which enables the light to be received by the gas sufficiently, and reduces the loss of light propagation. Secondly, the differential calculation of the output voltage of a single wavelength double channel pyroelectric detector is used to obtain the concentration of CO2 gas. Finally, the influence of shape parameters and auxiliary shape parameters of the generalized gaussian radial basis function neural network on improving approximation performance is analyzed. The experiment shows that CO2 gas absorption rate reaches its maximum value at a long axis length of 4 cm and a short axis length of 3 cm in the double semi ellipsoidal and double channel gas absorption chamber structure. At room temperature 250 C, the measurement error of different concentrations of CO2 is not much changed, with an absolute error fluctuation range of 0.004%~0.006% and the relative error fluctuation range is between 0.067%~0.100%. When the CO2 concentration is 2%, the measurement error varies greatly at different temperatures, with an absolute error fluctuation range of 0.001%~0.024% and the relative error fluctuation range is between 0.017%~0.400%. The average response time of a CO2 gas sensor with a measurement concentration of 2% for six times is 27.46 seconds, indicating fast response time.

Taking a certain high-precision tracking and search integrated photoelectric device as the target object, a high-precision opto-electronic turntable structure is designed according to the technical specification requirements of the product. By assembling and testing the precision opto-electronic turntable, it is ensured that the error of axis sloshing meets the requirements of this structure. Using ANSYS software to conduct modal analysis on the three-dimensional model of the opto-electronic turntable and opto-electronic equipment, it is concluded that the intrinsic frequency of the high-precision opto-electronic turntable and opto-electronic equipment is higher than the operating frequency, and does not produce resonance phenomenon. The application of the opto-electronic turntable shows that the structure design of the high-precision opto-electronic turntable is successful and it can be used as a reference for the structure design of similar opto-electronic turntable.

In this paper, the design optimization and simulation analysis on passive air-cooled finned heat sinks is carried-out for the heat dissipation issue of electronic components in the enclosed spaces of airborne. Firstly, a three-factor, four-level orthogonal experiment is designed based on the orthogonal experimental design method, which takes fin thickness, fin spacing and fin height into account. Then, CFD numerical simulation method is used to simulate and analyze heat sinks with different fin forms. Finally, the significance of the influence of various factors on the heat dissipation performance of the radiator is analyzed based on the extreme value analysis. The results show that the fin height has the greatest impact on the performance of the radiator, followed by the fin spacing and the fin thickness, and the optimal fin form is obtained.

In this paper, based on the practical application requirements of simulating infinitely distant target stars in high-precision star sensor ground testing tasks, and in view of the practical problems of large volume, difficult installation and calibration of conventional star simulators, an opto-mechanical structure of off-axis reflector star simulator with large aperture, long focal length and self-collimation function is designed to simulate the parallel light emitted from stars at infinitely distant distances. The design adopts off-axis reflective optical design to avoid center blocking. By adopting the focal plane splitting method of the optical tube, the transmission of the optical path through the reflection and transmission function of the semi-transparent semi-trans spectroscope is realized, and the length of the mirror tube is compressed. Collimation performance of the optical system can be directly distinguished by the detector receiving the light image transmitted by the beam splitter, which is easy to install and convenient for later use and calibration. And the use of the jackscrew to adjust the posture reduces the difficulty of mounting and adjusting. The actual test results show that the optical machine system has an inlet pupil aperture of ϕ210 mm and outlet pupil distance of 2100 mm, whose wave aberration (rms) of the whole optical machine system is 0.030, can accurately simulate 0~7 magnitude stars, and the working band is 500~800 nm. The design meets the requirement of calibration technical index for high-precision star sensor, and provides a design method for the efficient and rapid development of star simulator.

In this paper, an improved YOLOv5-based submarine target detector is proposed to solve the problems that traditional submarine target detection lacks robustness to complex backgrounds and noises, is sensitive to changes in illumination and viewing angle, and is difficult to deal with large-scale datasets. With the C3~~Transformer structure, the global context modeling ability of the features and the long-range dependency capturing ability are effectively improved. And the simOTA algorithm is employed to address the issue of imbalanced positive and negative samples in anchor-based algorithms, thereby enhancing the model's learning capabilities for small targets and challenging samples. Additionally, the decoupledhead approach is utilized to overcome the mutual exclusivity problem between classification and position prediction tasks, resulting in improved detection accuracy and robustness. The experimental results show that compared to the original YOLOv5, the improved model shows significant advancements in terms of Precision, Recall, mAP@0.5, and mAP@0.5∶0.95, with improvements of 2.8%, 10.9%, 3.8%, and 14.7% respectively, which indicates that the improved model achieves notable progress in terms of accuracy, recall rate, and average precision at different confidence thresholds in submarine target detection. Furthermore, the improved model effectively addresses the issues of "missed detection" and "false detection" in the actual detection task.

In unknown environments without global obstacle location information, real-time avoidance is a challenging task for unmanned platforms. To address this issue, a method that fuses deep neural networks (DNNs) with an improved artificial potential field (APF) algorithm is proposed in this paper. Firstly, YOLOv5s and a lightweight depth estimation model is used to construct an obstacle perception module to detect the location and depth of obstacles. Then, the target frame and equivalent depth are utilized to describe the three-dimensional information of the surrounding obstacles. Subsequently, the platform is projected onto the image plane, and the core area is calculated based on the positional relationship between the obstacle's equivalent depth grid and the core area to compute the direction of the core area in terms of the force on the virtual potential field in the image plane, the required yaw angle, and the linear velocity. Finally, the control system receives the signals and guides the unmanned platform to steer or brake, ensuring that the internal depth of the core area is greater than the safety distance. The experiment is based on monocular visible light and infrared for obstacle avoidance test, and the results demonstrate that the perception module can accurately detect the location and depth of common obstacles and the core area can intuitively reflect the positional relationship between the unmanned platform and surrounding obstacles. Compared to traditional methods, the proposed method relies on a monocular sensor alone to effectively avoid obstacles, achieving lower cost and flexible deployment, which provides a new idea for unmanned platforms to avoid obstacles in unknown environments during daytime and nighttime.

Aiming at the problem that aerial images are often affected by hazy weather with image blurring and loss of details, an improved SRGAN algorithm is proposed to remove haze in aerial images quickly and efficiently and restore image details and texture information. In this paper, the core structure of discriminator SResblock is redesigned and CBAM attention mechanism is introduced to improve the original SRGAN, and DH-SRGAN algorithm is proposed. The test results on the VISDRONE outdoor aerial synthetic fog dataset show that the proposed algorithm achieves significant improvement in the fog removal of a single image, with the defogged image reaching 24.48 dB PSNR and 95.29% SSIM compared to the original image, which are better than the traditional algorithms in both metrics. Compared with original SRGAN, the DH-SRGAN algorithm is more lightweight and suitable for embedding into the image preprocessing process of UAV reconnaissance missions.

Silicon photonic modulator is an important electro-optical conversion element in silicon-based optical links, and the performance of traveling wave electrode, as a key part of silicon optical modulator carrying microwave signals, is a core factor in determining the modulation efficiency and transmission loss of the modulators. Currently, the design of traveling wave electrodes is mainly divided into coplanar waveguide structure and coplanar stripline structure. A coplanar stripline has a larger design matching range with respect to a coplanar waveguide, but the signal shielding capability is lower than that of the CPW's double-grounded system, which leads to the emergence of problems such as higher-order mode excitation and multimode interference. In order to optimize the modulator performance, many scholars have proposed finger-shaped extension electrodes, T-shaped extension electrodes, segmented electrodes, and other shapes to optimize the electrode structure to achieve impedance matching while enhancing electro-optical interactions and reducing the transmission loss. This paper summarizes the research results of domestic and foreign scholars on traveling wave electrodes, and analyzes and prospects the development trend of traveling wave electrodes.