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 have 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.

this paper, a periodic lithium niobate (LiNbO3) electro-optical intensity modulator with a fiber pigtail-type Mach Zengde (MZ) structure is used for active Q-tuning, and a tunable filter is designed to be incorporated into the ring cavity structure to achieve stable output of tunable pulsed lasers with wavelengths in the range of 1882 nm-1992nm. By adjusting the signal frequency applied to the modulator, pulse lasers with a tunable repetition frequency between 15 kHz and 70 kHz are produced. At a repetition frequency of 15 kHz and a pump power of 1 W, the maximum single-pulse energy obtained is 6.4 J, with a peak power of 5.1W. This research exhibits advantages of all-fiber configuration and a wide tunable wavelength range, contributing to further exploration of the tunable range and potential applications of Q-switched pulse lasers.

An air-cooled large energy narrow pulse width MOPA laser pump by a high power laser diode array (LDA) is developed. The end pump Nd∶YAG crystal and decompress electro-optical Q-switching method are used in the oscillation stage and at the repetition rate of 25 Hz, 78 mJ single pulse energy, pulse width of 5.59 ns and beam quality factor of M2≈6.7 are obtained. The laser amplifying stage adopts side-pump zig-zag slab Nd∶YAG crystal dual-pass amplification mode, and at the repetition frequency of 25 Hz, a single-pulse energy of 439 mJ with a pulse width of 6.29 ns and a peak power of 70.46 MW was obtained, with an optical conversion efficiency of 15.25%, a beam quality factor of M2≈8.8, and a continuous operation of 3 min with an energy instability of less than 5%. When output in burst mode, the repetition rate is 1 Hz, the number of sub-pulses is 10, the interval of pulses of 2 ms, and the pulse envelope energy of 4.37 J. The laser adopts semiconductor thermoelectric refrigeration (TEC) combined with forced air cool as the heat dissipation mode, eliminating the bulky water cooling system and realizing the miniaturization of high peak power Nd∶YAG lasers and no water cooling.

Significant progress has been made in the navigation of autonomous mobile robots in indoor environments; however, poor map construction accuracy and poor path planning limit the practical applications of such robots. To solve these problems, a path planning algorithm based on guided search, the Gravitational Bidirectional Rapid Search Randomized Tree Algorithm (GBI-RRT) is proposed, which employs target bias sampling to efficiently guide nodes towards the target and reduce ineffective search. In order to further improve the navigation efficiency, another path reorganization strategy that eliminates low-quality nodes and improves the path curvature is proposed. It is integrated into a mobile robot based on a ROS system and evaluated in simulation and real environment experiments to verify the effectiveness of the above method. The results show that GBI-RRT outperforms the existing algorithms in various indoor environments.

In industrial production, precise control of liquid levels within containers holds paramount importance in ensuring smooth equipment operation and safeguarding the lives of maintenance personnel during production and transportation. This paper proposes the utilization of a laser swept frequency interferometry measurement system for liquid level assessment, which has many advantages, such as large measurement range, non-contact measurement, swift response time and convenient operation. Given that liquids exhibit a relatively high absorption rate for infrared light; the backscattered signal acquired by the measurement system is exceedingly weak, leading to a less-than-ideal signal-to-noise ratio. To address this issue, the phase accumulation method is introduced and combined with the measurement system to improve the accuracy of liquid level detection. In each cycle of the signal, the effective information carried by the signal remains consistent, and the noise information is then random. Therefore, employing the phase accumulation method not only amplifies signal strength but also elevates the signal-to-noise ratio. Further, by utilizing a phase-frequency sampling technique for nonlinear correction of the signal, followed by data processing, the liquid level information can be obtained. The experimental results show that the phase parameter accumulation method has a significant effect on increasing the signal strength and signal-to-noise ratio, thus providing a promising approach to enhance measurement precision under conditions of low signal-to-noise ratio.

Aiming at the problems of complicated installation and low measurement efficiency of existing inclinometers in measuring the maximum pendulum angle of large observation cars, a swing angle measurement method that combines feature filtering and projection conversion is proposed in this paper. This method uses a combination of LiDAR and surveillance camera data to achieve non-contact, accurate measurement of the swing angle of a large observation vehicle. Firstly, the point cloud of the swing arm is selected by a directional feature filter. Then, the irregularly shaped point cloud is removed by a shape feature filter. Next, the point cloud is projected to a two-dimensional plane and the edge straight line is fitted by the least-squares method to solve the swing angle. Finally, the average absolute value of the angle measurement error of the method is 0.29°, and the maximum absolute value of the error is 0.45°, which is obtained by the equal scale model experiment. The experimental results show that the method can effectively improve the efficiency and ensure the accuracy of the measurement of the pendulum angle of the large observation car.

Given the intricate design of tower facades, generating 3D models from a single data source often results in regional voids and exaggerated textural details. To address these issues, this paper proposes a 3D modeling method for tower buildings by integrating and synthesizing data from Unmanned Aerial Vehicles (UAV), airborne LiDAR, and handheld LiDAR. Illustrated by the case study of the vibrant Wucailou building in Xinping County, Yuxi City, Yunnan Province, data acquisition is conducted using UAVs and handheld laser scanners. Initially, separate collections of UAV imagery, airborne LiDAR, and handheld LiDAR data for the tower are undertaken. Subsequently, UAV image point clouds are generated adhering to photogrammetric principles. And then the three kinds of data are fused with alignment based on the nearest-point iteration algorithm method, and finally, the three kinds of data are fused with alignment by constructing a irregular triangular mesh to represent its 3D model. The experimental results validate that the 3D model derived from the harmonized multi-source LiDAR and UAV image data is more complete, which avoids the problem of voids that exists in the construction of 3D models from a single data source.

The performance of laser fuses in fuse-warhead system affects the effectiveness of the equipment. In this paper, taking the optical transceiver system as the object of study, based on the semiconductor laser life assessment, detector life assessment and equipment life test methods, a simulated life test of the laser fuse was carried out to analyze the changes in the performance of the optical system of the laser fuse and the reasons for such changes after the simulated life test.

In order to study the settlement and horizontal displacement inside the dam, a precise micro displacement measurement device is designed. Among them, the laser spot displacement detection algorithm based on two-dimensional image processing is an important component of the device. In this paper, an anti distortion laser spot center detection algorithm is proposed, in which the image of the divergent part of the spot is derived by threshold segmentation of the original spot, which is denoised and smoothed through closed operations and Gaussian filtering. Then, edge detection is performed using the sobel operator to obtain a smoother edge contour. Finally, the anti-distortion laser spot center detection algorithm is processed to determine the spot center. At the same time, a series of laser spot images are collected through experimental equipment, and processed and compared with the traditional laser spot center detection algorithm and the anti-distortion laser spot center detection algorithm. The results show that the anti-distortion laser spot center detection algorithm has the highest accuracy and effectively eliminates the influence of the aberration of the remote spot on the spot center calculation.

The efficient detection and extraction of lane lines is one of the key technologies that urgently need to be overcome in the field of autonomous driving. Many detection algorithms based on visual solutions have certain limitations due to the characteristics of image data, such as the impact of weather lighting on imaging quality and the difficulty of considering both curved and straight roads. This article proposes an algorithm for automatic extraction of lane lines by combining the advantages of 3D laser point cloud and road knowledge rules. Firstly, road surface points are obtained by enhancing the elevation differences of road boundaries multiple times. Secondly, the Isodata algorithm is simplified to adaptively obtain the threshold for intensity filtering. Then, the random sample consensus algorithm is used to detect straight line clusters and obtain candidate lanes. The candidate lanes are mapped into 2D vectors and correct lane lines are extracted through inter-class distance constraints. Finally, the vector topology consistency based on adjacent key feature point pairs is used to reconstruct the lane topology and obtain complete and meaningful lane lines in the real world. The algorithm achieves 92.46% recall, 94.79% accuracy, and 92.41% overall evaluation index with up to 5~6 lane lines. Experimental results prove effectiveness and feasibility of the method.

In this paper, the PAD used in infrared detector chips is investigated. Although many domestic and foreign infrared detector manufacturers, research institutes have published their own electrode system, but for the design of the electrode is rarely mentioned, for the electrode system of the thickness of each layer of the film design is even rarer. An electrode system is designed by analyzing the physical properties of commonly used electrode materials and the validation test results show that this electrode system does not affect the performance of the device and can meet the reliability requirements of the device.

With the rapid development of the third generation infrared detector technology, high operating temperature infrared detector has become an important development direction. This paper reports the research progress of the 11th Institute of CETC. in the miniaturization, low power consumption and high reliability of Dewar structure of high operating temperature tellurium cadmium mercury infrared detector. Through the optimized design of the Dewar structure, combined with the rotary integral cryogenic chiller K562S short, the component volume is 80 mm×61 mm×39 mm, and the weight is 212 g. The HOT component of medium wave cadmium tellurium mercury infrared detector with a starting time of 2.5 min and a working temperature of 150 K has been preliminarily completed, which has laid a certain foundation for the engineering application of high working temperature cadmium tellurium mercury infrared detector, and has certain guiding significance for the miniaturization, low power consumption and high reliability research of high working temperature cadmium tellurium mercury infrared detector.

Aiming at the problem of adaptive display method for high dynamic range infrared images in different scenes, an adaptive platform histogram display method based on image segmentation is proposed. Firstly, image segmentation is performed, and then the selection of platform values is discussed according to the segmentation results, and the basis for the selection of platform values is analyzed finally. The experimental results show that the proposed method obtains good display effect for different scenes and has practicality.

In response to the challenges of weak features, poor visual saliency, and variable morphology of Volatile Organic Compounds (VOCs), a high-precision gas leakage spectral video recognition algorithm based on time-space-frequency joint denoising and multimodal disparity matching model is proposed in this paper. Firstly, the high-precision identification of VOCs is achieved by mining the intrinsic information of high-dimensional time-space-spectrum data, and then the interpretability of traditional methods is organically combined with the powerful representation ability of deep learning through multi-module cascading joint optimization. Finally, by comparing the proposed gas leakage imaging method with international advanced gas monitoring equipment Sencia and Rebellion under the same conditions, it can be seen that the proposed gas leakage imaging method improves the accuracy of methane gas identification by 46.25% for low concentration, and reduces the false alarms to 1/3 of the original one, which verifies the validity and feasibility of the proposed algorithm, providing strong support for monitoring hazardous chemical leakage in the petrochemical industry.

The infrared radiation characteristics of a jet airplane in side-flying state are measured by a 3~5 m medium-wave and 8~12 m long-wave thermal imager, and the infrared radiation luminance distribution of the jet nozzle and tail flame is obtained. The results show that the mid-wave and long-wave radiation of the tail flame in this state presents a symmetrical envelope distribution, and with the increase of distance, the jet beam of the tail flame gradually diffuses, and the radiation brightness gradually decreases. Under the same circumstances, for the same case, the medium-wave band tail flame is about 3.5 times longer and 6.3 times larger than the long-wave one. The tail nozzle is the brightest part of the aircraft's radiation, with contrast ratios of 20.1 in the medium-wave radiation and 8.2 in the long-wave radiation.

Pulse wave is an important detection object for analyzing the physiological condition of human cardiovascular system. Pulse signals collected by wearable photoelectric devices often disturbed by motion artifacts due to human movement, which in turn affects the accuracy of detection results, and it is difficult to reduce the artifacts due to the fact that the main frequency components of the artifacts overlap with the frequency of the optoelectronic signals. In this paper, a pulse rate detection method combining nonlinear adaptive filtering and linear frequency-modulated Z-transform (CZT) is proposed to solve the problems of low pulse rate detection accuracy of existing pulse rate detection and insufficient resistance to motion interference. Firstly, the signal acquired by photoelectric volumetric pulse wave tracing (PPG) is preprocessed to remove high-frequency interference and baseline drift, and then the micro-electro-mechanical system (MEMS) is chosen as the reference signal to construct a nonlinear adaptive filter based on the least mean square (LMS) to remove the motion artifacts. Finally, the frequency spectrum of the signal is analyzed by CZT to calculate the pulse rate. The experiments are carried out by evaluating the performance of the experimental data collected from 10 subjects, and the results show that the method can effectively recover the original signal from the interference pulse wave signal, and the average absolute error of the measured pulse rate is 1.96 bpm, which is highly accurate and anti-interference ability.

High-frequency Satellite laser ranging (SLR) has the advantages of high accuracy, fast capture, large amount of observation data and high reliability. However, as the repetition frequency increases to more than 100 kHz, the existing measurement timing circuits cannot meet the requirements of system operation processing speed and real-time backscatter avoidance. In this paper, a design method for ultra-high-frequency satellite laser ranging timing circuits is proposed, using FPGAs instead of control computers for real-time calculation of gating distances, accurately generating gating signals to control the detector open, and using an alternating transceiver to adjust the laser ignition signal in real time to avoid backward-scattering interference. It can independently complete the calculation, storage and signal output of the distance gating output moment in laser ranging, and the highest working frequency is more than 500 kHz, which meets the requirement of 100 kHz ultra-high frequency ranging. The system has been successfully applied to the 100 kHz repetition rate SLR at Shanghai Observatory, and the standard point accuracy exceeds 200 m, which verifies the correctness and potential of the FPGA-based ranging timing circuit. The circuit is simple in design, high in resolution, and easy to interact with the host computer, which provides an effective solution for the design of the timing control circuit of the ultra-high repetition rate SLR system from 100 kHz to MHz.

Absolute attenuation coefficient is an important parameter to characterize the intrinsic optical properties of seawater, and its measurement in the field of water body absolute attenuation coefficient is of great value in the field of underwater photoelectricity detection. VIPER hyperspectral attenuation meter can be used to measure the attenuation coefficient of the water body, and it has a relatively obvious cost advantage compared with AC-S meter. However, VIPER can only measure the relative attenuation coefficient of the water body, and cannot directly obtain the absolute attenuation coefficient of the water body. To address this problem, this paper gives a VIPER-based field measurement of the absolute attenuation coefficient of the water body, the derivation of the basic formula for the VIPER measurement of the absolute attenuation coefficient of the water body, and the design of experiments to verify the reliability of the VIPER measurement of the absolute attenuation coefficient of the water body. Comparative experimental results show that the field measurement method of absolute attenuation coefficient of water body based on VIPER given in this paper has good accuracy and reliability. The method of this paper can make VIPER used in various underwater photoelectric detection fields, and realize the rapid calibration of the absolute attenuation coefficient of the water body.

In order to meet the high-precision requirements for machine vision for detecting the inner diameter of glass tubes in optical communication, as well as to address the influence of uneven lighting on detection accuracy, a large-aperture, high-resolution double-sided telecentric optical system with coaxial illumination through aberration balancing and optimization design is proposed based on the theory of four-component structural design. The system consists of a spherical lens and a splitter prism, with a magnification of 6×, F-number of 8, and an object numerical aperture of 0.3759, and is suitable for large format industrial cameras with a resolution of 65 million pixels. The design results show that the imaging quality of the system is close to the diffraction limit, the optical modulation transfer function is greater than 0.1 at the Nyquist frequency of 156 lp/mm, the maximum distortion is less than 0.1%, the object-image square telecentricity is less than 0.1° in all cases, and the system resolution is as high as 1 m.

Based on the light mapping method of optimal transmission theory, the initial parameters of the free-form optical system for zero extension light source are calculated for the design of the optical system for asymmetric illumination, with the distance from the light source to the irradiated surface of 20 mm, and the realization of the letter “JL” within the range of 50 mm×50 mm as the target. The initial parameters of the free-form optical system for zero extension light source are calculated, and based on this, the free-form optical system for zero extension light source and extended light source is optimally designed and simulated using LightTools software. The results show that for zero extension light source, the free-form surface diameter is 86.52 mm, the distance between the light source and the free-form surface is 34 mm, and the illumination distribution control of the letter “JL” can be realized on the irradiated surface; when facing the extended light source with a diameter of 10mm, the diameter of the free surface is 435.16 mm, the distance between the light source and the free surface is 242 mm, and the illumination distribution control of the letter “JL” can be achieved on the irradiated surface, indicating that the designed system can realize the asymmetric illumination distribution control and effectively improve the efficiency of the design of the free-form optical system.

This paper describesthe optical-mechanical structure design and analysis of a Cassegrain reflection system (here in after referred to as Cassegrain subassembly or Cassegrain system). At first decompose the index according to the design input. Finish the design of the Cassegrain subassembly. Then iterate and verify the design by tolerance and simulation analysis. At last verify the reliability and environmental probability of the machined and adjusted Cassegrain subassembly by environmental tests. The Cassegrain subassembly described in this paper has characteristics of high stability and rigidity, strong reliability and environmental probability. Also it meets the optical performance requirements.

Aiming at the problems of edge blurring and detail loss in the fusion of infrared and visible image, this paper proposes a fusion algorithm based on alternating guided filter (AGF) and mask-guided convolutional neural network (CNN). Firstly, the source images is decomposed into a base layer and a detail layer by alternating guided filtering. Then, the base layer is passed through the fusion rule with energy attributes to get the base fusion image, and the detail layer is guided by the loss function based on the mask guidance to get the fused detail image by convolutional neural network. Finally, the base fusion image and the detail fusion image are summed to generate the final fused image. The experimental results demonstrate that the proposed method effectively retains abundant background edge texture information while highlighting significant thermal targets, and achieves better results in objective evaluation metrics compared with the comparison methods, which proves the superiority of the proposed algorithm.

In this paper, a new evaluation method based on a multi-feature indicator decision tree is proposed to address the complexity in weight allocation for evaluation metrics and the flexibility of algorithm development platforms in camouflage effectiveness evaluation. The method selects five features, texture, color, brightness, structural similarity, and camouflage target size, as evaluation indicators based on visual attention mechanisms and trains a camouflage effectiveness evaluation model using a machine-learning decision tree classifier, which is ported to a small-sized, low-power Raspberry Pi development platform. Through the accuracy comparison experiment with two evaluation methods of mean weight method and entropy weight method, the accuracy of mean weight method is 56%, the accuracy rate of entropy weight method is 74%, and the proposed method achieves an accuracy of 90%. The real-time experiments demonstrate that the method can get the evaluation results of camouflage effect in about two seconds outside the field.

In order to solve the problem of different cost of image acquisition in different light segments, an image conversion method based on pix2pix was proposed. It mainly focuses on the generator and discriminator. In terms of generators, the residual structures generator was used instead of the original U-Net generator to alleviate the gradient vanishing problem. Deformable convolution is introduced to improve the generation effect of target edges and small targets. The BAM attention mechanism is introduced to improve the feature extraction ability of the algorithm for the main target in the image to improve the image generation effect. In terms of discriminators: change the number of convolutional layers in PatchGAN (the original PatchGAN is 3-layer convolution), and set up a control experiment to find the convolutional layer with the best conversion effect. Some KAIST datasets are selected for training and testing. The experimental results show that the Root Mean Square Error (MSE) of the improved algorithm is reduced by 31.4% and the Structural Similarity (SSIM) is increased by 11.2%, which can better realize the conversion between infrared and visible images.

Partial discharge detection is crucial to ensure the safe operation of high-power systems. In this paper, a surface plasmon resonance D-type photonic crystal fiber sensor for partial discharge detection in high-voltage equipment is proposed, and the scheme employs a photochromic gel as a sensitive unit for sensing the ultraviolet radiation generated by partial discharges. The refractive index of the gel varies with the radiation intensity, affecting the coupling resonance wavelength between the fiber core and the surface plasmon modes. The performance of the sensor is analyzed theoretically and simulated firstly by the full vector finite element method, then the geometric parameters of the sensor are studied to optimize the sensitivity of the sensor, and experimental verification is carried out finally. The results show that the sensitivity value of the designed sensor can reach up to 2.4 nm/mW·cm-2. The simple structure and low cost of the sensor provide a reference for the study of fibre optic partial discharge sensing.

As a core component for data transmission, the wavelength division multiplexer/demultiplexer (WDM) is extensively utilized in on-chip optical interconnect networks, where the most crucial parameters for these devices include device size, insertion loss, and crosstalk levels. To address the issues of large size and uneven optical power distribution in conventional silicon-based arrayed waveguide gratings (AWGs), a 1×4 WDM based on a silicon-on-insulator (SOI) platform incorporating a ring reflector-assisted multimode interference waveguide is proposed, which can realize the wavelength separation of different channels. The core size of the device is only 10 m×34 m, and the minimum crosstalk between adjacent channels is -14.42 dB.