With the development of laser technology, high laser-induced damage threshold (LIDT) is required for optical thin film devices used in high power and high energy laser systems and laser protection systems. However, at present, there are still some problems in the measurement of LIDT, such as inconsistent measurement standards, poor repeatability, poor accuracy, and difficult comparison of mutual results. The main reason is that different measurement materials and film stacks are suitable for different damage discrimination methods. In this paper, the research on damage identification method are summarized, and the image method, scattering method, plasma flash method, plasma spectrometry and so on a variety of different damage identification method are presented, the principle and characteristics of various methods, as well as the effect of damage criterion, the research on laser damage threshold test work are described in this paper. It is expected to be a reference for the research work of LIDT test.

With the improvement of industrial automation, the demand for online real-time measurement of workpieces is growing. It is of great significance to detect the difference between the three-dimensional morphology of the measured workpiece and the standard workpiece, so as to realize the rapid screening of qualified products. The traditional 3D difference detection method usually adopts the reverse fringe technology. It is based on the coordinate correspondence between the camera and the projector, and the stripes projected on the standard workpiece are distributed in a straight line. When the workpiece to be measured is placed at the same position, the difference between the workpiece to be measured and the standard workpiece is directly reflected by the deformation of the straight stripe. In this paper, a real-time computer-generated moire profilometry(CGMP) for workpiece 3D difference detection is proposed. The single frame acquisition characteristics of CGMP are calculated. Only the wrapped phase is calculated and the difference evaluation function model is established. The size of the evaluation function is used to directly reflect the difference characteristics. The alignment position between the standard workpiece and the measured workpiece is tracked through the minimum point of the evaluation function, so as to achieve accurate detection of the difference between the two. The collected fringe data information has been saved in the process of difference detection. The real-time 3D reconstruction can be performed directly at the alignment position. The experimental results verify the feasibility of the proposed method in 3D difference detection.

Due to the influence of its optical structure, when using the method of machine vision to detect the surface defects of spherical optical components, it is impossible to image the measured surface on one image plane, and the three-dimensional information of the defects is lost during the detection process. detection error.To solve these problems, a detection method combining machine vision and 3D reconstruction is proposed. First, an image acquisition platform is designed according to the characteristics of spherical optical elements to obtain high-quality defect images. Then, the defect image is preprocessed and identified by the image processing algorithm.Finally, based on the computer vision image reconstruction technology and the spherical center projection technology, the 3D reconstruction is carried out on the image of the defect. Experimental results show that this method improves the accuracy of machine vision detection of spherical optical components surface defects, up to 99%, which is feasible and valuable for research.

In order to obtain the surface gradients in phase measurement deflectometry (PMD), horizontal and vertical phase-shift fringe images need to be obtained respectively, so more images are usually required. In order to reduce the number of fringe patterns, a new phase acquisition method based on composite fringe patterns is proposed, which is realized with five compound oblique fringe patterns by superimposing the horizontal and vertical phase information to form oblique fringes. The phase measurement accuracy is higher than that of the five-step crossed grating phase-shift method. Furthermore, the phase acquisition method is improved to overcome the second-order nonlinear error of the system by using seven compound oblique fringe patterns. Computer simulation and experiments show the feasibility of the proposed method, and its measurement accuracy is higher than that of the crossed fringe method with the same number of frames.

In order to solve the problem that the solidification stress of the micro thick adhesive layer used for optical component bonding cannot be determined under constant temperature, a dynamic monitoring system for the curing state of the micro thick adhesive layer is designed. Firstly, the monitoring principle of the micro thick adhesive layer is established through the analysis of the generation mechanism and influencing factors of the constant temperature solidification stress in the micro thick adhesive layer, and the scheme of the monitoring system of the curing state of the adhesive layer is formulated. Then the key components of each functional module are designed in detail. The stiffness, deflection and deformation of the supporting structure are calculated in details and analyzed by finite element method, and the assembly model of the whole machine is established based on the assembly pattern. Finally, the performance of the system designed to detect curing state is verified by experiments. The results show that the optimized monitoring system is reasonably designed, and the overall stiffness of the U-shaped structure with 45° support angle is 84% higher than that of the initially selected 7-shaped structure. Using this system for practical application, the characteristic curing tensile stress value in the curing stage of the adhesive layer is monitored and obtained, and the application effect is good. This study provides a theoretical reference for the curing principle of micro thick adhesive layer, and makes it possible to monitor the curing state of micro thick adhesive layer under constant temperature.

In order to realize high-precision and fast three-dimensional (3D) shape measurement with high-frequency fringes, a method using dual-frequency heterodyne and spatial-temporal phase unwrapping is proposed. In this proposed method, only two sets of high-frequency fringe patterns are needed to project, the wrapped phase distribution of low-frequency fringe is calculated by using the dual-frequency heterodyne method, and its corresponding unwrapped natural phase can be obtained by spatial phase unwrapping manner, which will be used to guide the unwrapping process of the phase of high-frequency fringe and finally recover the absolute phase distribution required for 3D reconstruction. This method performs spatial phase unwrapping on the low-frequency wrapped phase, which reduces the difficulty and increases the application range of 3D shape measurement based on dual frequency fringe projection. The experimental results show that the STD error of this method is 0.06 mm. Therefore, this proposed method can realize high-precision and fast 3D shape measurement only using two sets of high-frequency sinusoidal fringes and without adding a third frequency fringe pattern.

A mathematical model of film thickness uniformity of planar three-stage planetary fixture is established. Based on this model, a computer simulation program is compiled to study the film thickness uniformity of planar three-stage planetary fixture used in 1.8 m large diameter coating machine. Taking Opt-run OTFC-1800-DCI coating machine as the simulation object, the effects of evaporation source characteristics, planetary fixture inclination and planetary orbit radius on film thickness uniformity are analyzed. The simulation results show that the inclination of planetary fixture is the main factor affecting the film thickness uniformity of planar three-stage planetary fixture α= 64°, the film thickness distribution is the most uniform, and the non-uniformity is 0.1%. The radius of planet orbit also has an effect on the uniformity of film thickness. When the radius of planet orbit is 665 mm, the film thickness distribution is the most uniform, and the film thickness uniformity is controlled within 1%.

With the increase in firing rate and ammunition volume of body barrel firing weapons, the mechanical characteristics of the bore plating have put forward higher requirements, making the traditional electrochromic plating process has gradually failed to meet its needs. In this paper, 20 μm and 50 μm metal chromium coatings are prepared by vacuum arc ion plating technology on the substrate surface of PCrNi3MoV alloy steel (special steel) by the same process, and their surface morphology, mechanical and tribological properties are tested. By studying the effect of coating thickness on morphology, it is found that thicker coating plays a positive role in reducing surface defects and improving surface quality. By testing mechanical and tribological properties of the substrate surface before and after coating, it is found that the friction coefficient of the coating is between 0.32 and 0.42, which is 0.02 lower than the current Cr coating prepared by arc ion plating technology in China (0.35~0.45). The bonding strength of the coating with the substrate is 45.3 N, and the microhardness reaches 15.01 GPa. In the process of comparing the plating thickness on the surface wear resistance, it is found that the deposition of thicker plating is beneficial to the improvement of wear resistance, in which the 50 μm thick Cr plating has only slight wear on the surface after 1 800 times, and the wear rate is 0.000 13 mm3/(N·m). Compared with the uncoated substrate, the wear resistance is improved by 75.93%. This will be of great significance in extending the service life of the artillery barrel and promoting the development of protective coatings.

In order to solve the problems of narrow detection band and low resolution of space-to-ground remote sensing optical system, an aspheric off-axis triple inverse optical system is designed. The off-axis field of view of the computed coaxial tri-reflective structure is processed, the aberration is optimized, and the imaging quality of the off-axis tri-reflective system is analyzed and evaluated. The resolution of the designed optical system is improved in the visible and short- and mid-wave infrared bands, reaching 2 m, 3.3 m and 10 m ground resolution, respectively. The system has three reflectors with even aspheric surface, 600 mm focal length, 1/4.3 relative aperture, 8°×4° field of view and 0.4% maximum aberration. The MTF value at Nyquist frequency is higher than 0.2 for each band, and the RMS radius meet the imaging requirement of less than the minimus image element size of the detector. The high resolution and wide band design objectives have been achieved, thus enhancing the system's all-weather information acquisition capability.

With the development of display technology, people can get immersive experience and more realistic stereoscopic visual enjoyment from three-dimensional (3D) display. In order to improve the imaging quality, the collimating backlight integral imaging system can converge the divergence angle of pixel light, effectively reduce the tendency of voxel diffusion behind the central depth plane, thereby reducing the size of reconstructed voxels and improving the resolution of the system. However, the light propagation of collimating backlight system is different from the traditional scattering backlight system. There is deviation compared the light propagation path of both system, which leads to the pixel mapping error of the sampling light, and then induce voxel drift and aliasing. Therefore, in this paper, we propose a precise method to generate elemental image array. By combining reverse ray tracing technology, we establish the ray propagation geometry of the collimating backlight system, re-determine the starting point and direction of the sampling ray, and reversely track each rayed, so that the information of each ray is correctly mapped to the corresponding pixel. The experimental results show that the proposed method can effectively correct the light deviation, solve the problems of voxel drift and aliasing, and improve the imaging resolution of the system.

Femtosecond laser in green band is usually generated by frequency doubling of Ti: sapphire femtosecond laser. However, the high cost of Ti: sapphire laser and poor stability of its solid system limit the application of femtosecond green laser. In this paper, the femtosecond seed source based on SESAM passive mode-locking and chirp (CPA) technology are used to generate 1 030 nm fundamental frequency light. After compression and frequency doubling, the 515 nm femtosecond laser with pulse width 2 W is achieved. The femtosecond laser has the ability to switch the output of fundamental frequency light and frequency doubling light, and has the advantages of compact size, stable pulse, high conversion efficiency and good beam quality. It can be used as the light source of ultrafast laser processing system.

The optical thin films play a very important role in the regulation of the light field in the laser system, but they are also easily damaged by the cumulative effect of high-energy-density pulsed laser irradiation. The damage such as melting and cracking occurs. In this paper, Ta2O5/SiO2 double-layer antireflection coating (183.33 nm/249.3 nm) is designed. Based on the thermodynamic principle, the temperature field and stress field model of the laser-induced Ta2O5/SiO2 double-layer film are constructed. The temperature and stress of the film were simulated. The results show that when the laser irradiates the Ta2O5/SiO2 double-layer anti-reflection coating, the coating layer is thermally damaged and thermal stress is generated, the thermal stress changes abruptly, and the coating layer is thermally induced stress damage. The damage mechanism has important guiding significance.

All-optical phase modulation is an important part of all-optical signal processing, which is of great significance to the realization of all-optical networks. Semiconductor optical amplifier (SOA) is a key component of all optical phase modulation system because of its high nonlinear coefficient and small size. However, due to the concurrence of cross phase modulation and cross gain modulation in SOA, the power fluctuation of current SOA-based phase modulation signals is inevitable, which affects the signal quality. Therefore, an all-optical phase modulation scheme of cascading SOA controlled by differential balance signal is proposed, and the principle of the scheme is analyzed. Then, the all-optical phase modulation is realized through experiments, and the waveform fluctuation caused by SOA cross gain modulation is eliminated during the phase modulation process, and the principle is verified. This modulation scheme is of great significance to realize all-optical wavelength conversion for high-order coding formats and improve the flexibility and expansibility of the network.

Semiconductor single-photon avalanche photodiodes can carry out weak signals detections and have important applications in quantum communications, lidar and atmospheric detection. Although the performance of semiconductor single-photon avalanche photodiodes mainly depends on the design of detector chip, chip fabrication technology and design of peripheral matching circuit, the subsequent packaging technology also has an important influence on its performance. This paper focuses on the packaging development of semiconductor single-photon avalanche photodiodes over the years. The corresponding packaging forms and technologies briefly are introduced, as well as the impact of packaging on the performance of avalanche photodiodes. Finally a prospect for the packaging development of semiconductor single-photon avalanche photodiodes is presented.

Auditory perception is an indispensable function of mobile robots. Electroacoustic microphones have the disadvantages of low sensitivity and susceptibility to electromagnetic interference, which greatly limits the use of mobile robots. In this paper, a Fabry-Perot interferometric (FPI) optical fiber microphone is used to replace the electroacoustic microphone, and a cross-type array is constructed on the mobile robot platform. The FPGA-based signal processing and sound source localization algorithm software is designed to realize the functions of robot auditory perception and passive acoustic navigation. Firstly, the working principle of FPI fiber optic microphone is introduced, and its sensitivity with electret microphone is tested and compared. Then, the FPGA-based time difference of arrival (TDOA) localization algorithm was optimized, and the design and integration of the sound source localization system on the mobile robot was completed. Experiments show that when the average distance is 6.60 m, the average error of indoor positioning azimuth is 1.54° and the average error of distance is 0.09 m and the average error of outdoor positioning azimuth is 1.84° and the average error of distance is 0.16 m. The robot can accurately reach the position of the sound source. All these show that the system has strong practicability and broad application prospects.

China's power grid technology is developing towards informatization and intelligence. Targeted management platform research is one of the most effective construction and upgrading methods of power related projects. Based on the technology of image recognition and internet of things, a new substation facility management system is designed, which extracts the image feature points with surf recognition algorithm and calculates the feature vector through the euclidean distance method, so as to quickly identify the substation facility image, and use the established substation facility management system to provide diversified information such as engineering situation and facility status to the on-site construction personnel. At the same time, intelligent applications are developed under the hybrid architecture to support the use of a variety of intelligent mobile terminal devices. The development and use of this system can improve the construction efficiency of substation facilities, and then reduce the construction, reconstruction and supervision costs of related projects. Finally, the substation facility management system designed for a substation test institute verifies the reliability and effectiveness of the system.

For piezoelectric ceramic fast steering mirror, a transfer function identification method based on frequency domain analysis is designed, which can realize frequency sweeping and transfer function fitting for any system with known transfer function order. Then the fitted transfer function of piezoelectric fast steering mirror is used for controller design, simulation, and physical verification. The closed-loop performance of the designed controller is verified, which achieves a bandwidth of 600 Hz and a step response time of 12 ms.The results show that the controller meets the performance requirements.The equipment will be affected by temperature drift during operation, therefore the relationship between temperature, optical deflection angle and control voltage is used for temperature compensation. The experimental results show that the temperature compensation function can suppress the temperature drift by 90%, which greatly improves the system control accuracy.

The control of two-dimensional scanning mirror may encounter the problem of pulse interference and the parameter uncertainty caused by the equipment manufacturing error. A method for calculating the conservative bound of impulse response and designing a state feedback controller is proposed based on the robust pulse-peak theory. The parameter uncertainty should be considered when modeling the azimuth motor servo control system of two-dimensional scanning mirror. After LMI optimization, the conservative boundary of controller parameters and peak response is obtained. The simulation results show that the proposed method reduces the peak response by 20% and the recovery time by 50% compared with the conventional PID control method, and has a good suppression effect on the pulse interference of the two-dimensional scanning mirror.

The optimal configuration process of the AC-DC hybrid power system will be affected by the output uncertainty of photovoltaics and wind turbines, and the power system planning effect is poor. Therefore, a medium- and long-term double-layer optimal configuration planning method for the AC-DC hybrid power system is designed. We will introduce the binary variable model into the uncertainty model, calculate the influence parameters of wind and light resources on the optimal configuration of the AC-DC hybrid microgrid, calculate the power flow of the AC-DC power system, set the objective function and system power conditions, perform capacity optimization, and realize AC-DC power flow. The experimental results show that the proposed planning method improves the estimation accuracy of the voltage phase angle interval and the voltage amplitude, and also reduces the commutation loss and planning cost, and meets the actual design requirements.