This PDF file contains the front matter associated with SPIE Proceedings Volume 12585, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

The standard evaluation methods of the imaging quality of optical imaging systems are divided into evaluation methods based on electrical signals and evaluation methods based on images, but the impact of environmental testing on the imaging quality is rarely studied. This paper aims to analyze the imaging quality of a typical optical imaging system before and after the salt mist testing. By studying its imaging resolution and setting up different optical environments, the influence of salt mist testing on its imaging resolution under different optical environments is discussed here. It is found that different illumination conditions have great influence on imaging resolution, and good illumination conditions can effectively improve the resolution of camera products. In the other hand, salt mist aging testing has a great influence on the imaging resolution of the camera products, and longtime exposure to sodium chloride solution has an irreversible effect on the imaging performance of the camera. The tolerance of cameras to salt mist aging test shows two-level distribution. Some products are completely invalid, and some products have good tolerance and no obvious failure.

Temperature is one of the main factors affecting the normal operation of the optical system of laser communication equipment. Based on the requirements of the air-based platform for the surface shape index of airborne communication equipment, the optical-mechanical thermal integration analysis method is used to analyze the optical system of an airborne communication optical machine. Firstly, the finite element model of the air-based laser communication prototype is established. Secondly, the temperature field distribution and thermal deformation characteristics of the optical system structure during the full-load operation of the communication prototype are extracted by Ansys Workbench finite element analysis software, and the surface shape changes of the primary and secondary mirrors of the beam expansion system under the action of the heat source load are obtained. Finally, the optical software program SigFit is used for Zernike polynomial fitting, and the performance of the laser communication prototype beam expansion system is evaluated according to the fitting results. The results show that the maximum axial displacement of the primary and secondary mirrors of the beam expansion system is less than 0.02mm under both horizontal and vertical conditions of the optical axis when the communication optical machine is fully loaded at an ambient temperature of 22℃, and the mirror surface shape is better than λ/50, which meets the performance index and can adapt to the temperature environment requirements of airborne communication equipment on air-based platforms.

The ultra-efficient standard light baffle plays an important role in the calibration of the stray light test system. In this paper, a three-class baffle is designed. And a design scheme of the baffle with honeycombed wall is proposed, by analyzing the stray light transmission model and suppression mechanism, which can meet the requirements of a baffle with ultra-efficient stray light suppression capability. A simulation model of the baffle was established. The simulation of baffle show that when the stray light suppression angle is greater than 8°, the PST value of the baffle reaches 10^-6 magnitude. When the stray light suppression angle is greater than 17°, the PST value of the baffle reaches 10^-12 magnitude, which can meet the needs of ultra-efficient calibration of laboratory stray light test systems.

Laser degumming is a new technology in the maintenance of press valve, which has the advantages of high efficiency, high accuracy, complete degumming and low pollution. However, the metal matrix is prone to thermal damage when subjected to laser action. It is found that 1Cr18Ni9Ti is the most prone to oxidation. If 1Cr18Ni9Ti is not damaged, 2A12 and HPB59 materials will not be damaged under the same laser parameter processing. The internal metallographic structure of 1Cr18Ni9Ti sample does not change when it is oxidized at the boundary without illumination. Therefore, if the nonilluminated surface does not oxidize, it can be considered that the internal metallography of the press valve has not changed; The simulation model of rubber removal was established, and it was found that the method of switching off and on light could control the temperature in the process. When the time ratio of switching on and off light was 1: 3, the rubber residue could be completely removed without damaging the rubber press valve. The simulation parameters are applied to the actual parts experiment, and the simulation results are verified to be reliable, the temperature is controllable and the parts have no damage. The research results in this paper can achieve the task of rubber removal without damaging the substrate.

The warpage deformation of a silicon plate is monitored in real-time using distributed optical fiber and the influence of data resolution on the measurement result is studied. The experimental results show that this method has good accuracy and the relationship between data resolution and measurement error is non-linear.

Aiming at the stability control requirements of high stability solar simulation light source, a white laser power stability control method based on quartz is proposed. The quartz plate is connected and fixed with the scanlab, and the relationship between the Angle of the incident light and the transmittance is taken as the signal regulation principle. When the scanlab rotates the quartz slab, the light signal transmitted by the quartz slab is adjusted. Based on Fresnel's Law, the rotation Angle and transmittance parameters under different wavelength of incident light are analyzed. And the rotation Angle range of quartz is calculated, which provides the output parameter support for realizing the power stability of light source. PID algorithm is used to modulate the error of the signal of the monitoring detector and the voltage corresponding to reference power so as to accurately adjust the output of scanlab. The stabilizer is used to control the power of the white laser, and the Trap detector is used to verify the level of power stability. The experiment results of the stability of the laser after modulation is as follows: the standard deviation C_V is 0.069%/55min and the peak-to-peak fluctuation S_V is ±0.302%/55min. Compared with the free-running result, S_V and C_V are improved to 1/15.83 and 1/33.04 respectively, and the power stability of the white laser is enhanced, meeting the stability requirement of 99.6%.

The high sensitivity Mz rubidium laser optically pumped magnetometer has important applications in geomagnetic field measurement and geophysics exploration. In this paper we analyze the principle of Mz rubidium laser optically pumped magnetometer. We take rubidium 87 isotope ( ⁸⁷𝑅𝑏) as the core material of magnetometer, set up a high sensitivity laser optically pumped magnetometer experimental system and carry out magnetic measurement experiments. The experimental results show that the signal strength is 185 mV, the line width is 1.55 kHz. The intrinsic sensitivity of this magnetometer is 33.51 pT/Hz^1/2. The research work provides technical support for the development of high sensitivity rubidium laser optically pumped magnetometer.

The spin polarization of ⁸⁷Rb and ¹²⁹Xe atomic ensemble has great impact on the signal intensity of a nuclear magnetic resonance gyroscope. The coupled spin polarization modelling process for ⁸⁷Rb and ¹²⁹Xe atoms ensemble is presented in detail. Three dimensional spatial distribution of the spin polarization field is obtained by numerical solution and is in good agreement with the experiment results. Influencing factors including temperature, power and detuned frequency of the pumping laser, average collision times of anti-relaxation coatings and partial pressure of gas composition are investigated. The work presents an indirect method to estimate the average collision times given the Xe polarization with different temperatures. It is found the average collision times of the ¹²⁹Xe atoms with the inner surface of a bare glass cell of 3×3×3mm³ can reach up to about 2.7×10⁵ times. It is also found that the pumping frequency corresponding to the maximum polarization of the Xe atoms polarized by spin exchange of Rb atoms is not consistent with the D₁ line of the ⁸⁷Rb atom when the temperature of the cell is above a certain temperature, but is detuned at a certain frequency. Quantitative analysis of the effect of anti-relaxation coatings on the spin polarization suggests that the appropriate average number of collisions of the Rb atoms with the inner surface of the cell is about 1500 times.

Ghost imaging, a new type of active imaging, has attracted much attention because of its unique imaging mechanism. As an important application of ghost imaging, three-dimensional correlative imaging has been developed in recent years. At present, the main method of 3D ghost imaging is to use the time-of-flight method to obtain the distance from the target object to the imaging system. However, this method is not easy to achieve millimeter-accurate distance measurement in the distance range within 1m because of the limitation of the measuring instruments. In this paper, by using binocular stereo vision which is a more intuitive 3D imaging method combined with computational ghost imaging, millimeteraccurate distance measurement can be performed on objects within 50 cm. Binocular 3D ghost imaging performs well at close range and is relatively simple to implement, which may help robots avoid obstacles and medical imaging.

In this paper, the eigenvalue of the super-high precision stable resonator is used as a reference frequency, and the wide-linewidth semiconductor laser is used as a light source. To keep costs down, this work combines the optical feedback effect with the Pound- Drever- Hall laser frequency stabilization method, abandons the electro-optic modulator used in the traditional technology and adopts the optical path tuning method to carry out the phase modulation of the incident light field. The document derives from the shape of error signal in frequency stabilization technology in the presence of optical feedback effect notionally. As per this error signal, the length of resonator cavity is controlled by feedback controlled via the circuit system, and then successfully stabilizes the resonant frequency of the resonator at the center frequency of the laser output.

In order to ensure the measurement accuracy and long-term working stability of the laser methane sensor in the field environment such as coal mines, a design method of a high-precision double-closed-loop laser temperature control system based on the laser absorption peak and working temperature is proposed to improve the temperature control system of the DFB laser. control accuracy. Based on ADN8834 integrated TEC controller chip, the temperature control system based on PI compensation network is designed, and the simulation analysis of the temperature control system is carried out. In order to verify the accuracy and long-term working stability of the temperature control system, the laser methane sensor has passed the (-20~60)℃ high and low temperature experiment. The application of methane sensors in industrial sites such as coal mines provides technical support.

Carbon monoxide (CO) is an important object for atmospheric quality and medical diagnosis, and its trace concentration detection technology has been of great attention. For this purpose, various new detection methods have emerged, such as cavity ring down absorption spectroscopy and cavity enhanced absorption spectroscopy. In this paper, the demand for CO ppm-level trace concentration detection is taken as the traction, and an optical feedback cavity enhanced absorption spectroscopy system with an equivalent noise absorption sensitivity of 7.4×10^-10cm^-1Hz^-1/2 is established to carry out the experiment of near-infrared detection of CO gas concentration. Based on the measurement data of the OF-CEAS system, the minimum measurable CO concentration of the system was inferred to be 1.98 ppm. This system can be developed as a portable respiratory gas diagnostic device and an atmospheric trace gas detection device such as NH₃ and CO.

Denoising is significant in many fields, especially for computational imaging. Coherent diffraction imaging and speckle correlation imaging are regarded as the most promising computational imaging techniques. The above two imaging techniques can be classified as phase-retrieval-based imaging due to the phase-retrieval is a vital procedure for object reconstruction. However, the acquisition process would generate unavoidable noise and participate in the iteration process of phase-retrieval. Hence, it is necessary to denoising after obtained the original reconstruction image. Here, a denoising method that based on connected domain is proposed for phase-retrieval method. We experimentally demonstrate the denoising results and quantitatively analyze the effect. Comparison of the classical median filter, wiener filter and bilateral filter, our method shows a satisfactory denoising effect. Our results prove that connected domain denoising is useful and promising, which provides a new post-processing denoising method for phase-retrieval-based imaging.

Large alumina electrolysis baths operate at high electrical current and high temperature hence a number of safety hazards. Conventional safety inspection relies on manual temperature monitoring using IR remote thermometers, which is not in real time and not reproducible. This paper presents a distributed fiber optic temperature sensor (DTS) system based on Raman scattering principle. The operation principle and method of deployment of the DTS system in an alumina electrolysis base and on-site monitoring results are discussed. The field measurement results show that the accuracy of the measurement of the distributed fiber optic temperature measurement system meets the application requirements and have great application potential.

Moving the sound transmission device along the sound transmission path (wire rope) point by point is a common measurement method for the acoustic field characterization in an anechoic chamber. In the actual testing process, due to the influence of the weight of the sound transmission device and the wire rope, the sound transmission path will change from an ideal straight line to a curve, resulting in the measurement error for acoustic characteristics. In this paper, the catenary theoretical model is established to describe the sagging wire rope. To consider the gravity of the sound device, the finite element method is used to simulate the sound transmission path. The experimental validation shows that our model can better express the deviation of the sound transmission path concerning gravity. It is of great significance to improve the accuracy and reliability of measuring the acoustic characteristics in an anechoic chamber.

At present, temperature sensors are relatively mature, and commercial sensors are mainly thermistors and thermocouples, which have the advantages of low cost and large temperature range. However, it is difficult to meet the requirements of some special occasions, such as strong electromagnetic interference, strong corrosiveness and other environments, and high-precision temperature measurement cannot be performed. Fiber Bragg grating is a kind of fiber optic sensor, which has the advantages of anti-electromagnetic interference resistance, corrosion resistance and high sensitivity. The fiber Bragg grating obtains sensing information by modulating the Bragg wavelength of the fiber through the change of the external temperature parameter, and can automatically monitor the temperature change of the object to be measured. In this paper, the temperature sensing test experiment of fiber Bragg grating is carried out. The results show that the center wavelength of the grating has a good linear response to the temperature of the object to be measured, and the temperature error is within ±0.5℃. temperature sensing.

The high spectral lidar principled sample machine that can obtain the target spectral information as well as the twodimensional images was developed from the perspective of motoring the marine oil spill pollution in this thesis, this high spectral lidar principled sample machine can cover the wavelength range from 400nm to 1100nm. And this high spectral lidar principled sample machine was applied for the remote sensing detection of vegetation, oceans, minerals and some other ground object targets, through measuring the spectral radiance of the hyperspectral laser interacting with the target and returning to the lidar receiving system, so as to realize the real-time monitoring of vegetation, oceans and minerals. For the purpose of realizing the quantitative observation, an accurate radiometric calibration on high spectral lidar was required. The radiometric calibration of high spectral lidar was aimed at its receiving system, that was to determine the responsivity of the principled sample machine to the target spectral radiance. After finishing debugging, all the indicators of the principled sample machine can meet the application requirements, which provided a new monitoring means for the marine oil spill in our country and was of great significance for the future protection of marine environment and the application and exploitation of marine resources.

Glasses-free three-dimensional (3D) display has attracted widespread attention because of its multi-perception, interactivity and immersion features. Limited by the resolution of the display, the number of views and the spatial resolution of the views are contradictory. In this paper, we propose a vector light field display with multi-directional backlight, which is realized by two directional backlight illumination display modules. By analyzing the deflection error of diffracted light, a suitable directional backlight angular separation is designed. Experimental results show that the proposed prototype generates full-color 3D images that satisfies binocular parallax for the observer, effectively eliminates the gaps between views. The multi-directional backlight module is adopted to maximize the use of the number of views and expand the field of view (FOV). Potential applications include entertainment, exhibition displays, and education.

In terms of light field image array generation, the traditional method of multi-view parallax image synthesis has problems such as computational redundancy and slow pixel mapping. We propose a new design method for light field image arrays for 3D printed images based on backward ray tracing techniques. The farthest point of collision is found when a ray collides with an object. The rendering time is greatly reduced compared to traditional methods, and only related to the resolution of light field image array. Combine with microlens array, 3D printing image with continuous and dynamic parallax effects is obtained, the correctness of the algorithm is proved.

The phase screen with different atmospheric turbulence intensities was numerically simulated by Fourier transform method. Meanwhile, the phase and light intensity distribution characteristics of the Gaussian laser beam passing through the atmospheric turbulence were numerically studied, and the theoretical results and practical conclusions of the atmospheric phase screen were verified. The results show that the phase screen produced by Fourier transform method can intuitively illustrate the phase characteristics of atmospheric turbulence, and the phase and light intensity distribution of the Gaussian laser beam passing through atmospheric turbulence of different intensities were consistent with the theoretical analysis. Numerical simulation has certain guiding significance for the engineering application of laser transmission in the atmosphere.

The core of the study of metalens is the wavefront shaping of incident light using optical elements whose thickness is in the wavelength range. This integrated and miniaturized optical structure will be widely used in common optical instruments and nano optical devices. In this paper, the phase and group delay of light are controlled by designing the nanostructured unit, and the achromatic metalens with a large bandwidth is realized. However, achromatic metalens does not cover the whole visible spectrum. In this paper, the author demonstrates an achromatic metalens for a certain wavelength of visible light (400nm-600nm).

VR installation and detection tasks require the ranging system to combine a high accuracy with a large depth of field and to collect reflection peaks from multiple reflective surfaces. Currently, there is no corresponding device to assist VR optical assembly detection, including tilt, eccentricity, and spacing of lens assembly. To fill this gap, this study applied the FMCW lidar-based ranging system to VR optical testing. Through nonlinear correction and introducing an axicon lens in the optical system, a high-precision FMCW ranging system with a 20 mm depth of field was obtained. The ranging accuracy and ranging resolution of the system could reach 1.3 μm and 14.3 μm, respectively, and the planes of the three glass layers could be simultaneously measured. The proposed system application made it possible to perform the installation and adjustment detection of the multi-lens optical system of VR.

In this paper, the three-dimensional real-life model and laser point cloud data are briefly introduced, and then the actual demand of cadastral survey under the background of big data is put forward. Finally, based on this, a new cadastral survey method is developed. Among them, it consists of three links, namely, data acquisition, data processing and the construction of cadastral model map. At the same time, the application effect of this method is verified from the aspects of result precision, work efficiency and comprehensiveness. Through verification, it can be found that, compared with the traditional surveying and mapping method, the surveying and mapping method based on 3D real-life model and laser point cloud data has higher accuracy, faster working efficiency, and can visually display the results, which is far superior to the traditional surveying method, and can be applied to practice.

The excellent properties of the narrow linewidth, single longitudinal mode and constant frequency of the seed-injected solid-state single-frequency pulse laser make it suitable in the applications of the gravitational wave detection, doppler wind radar, and greenhouse gas flux measurement. FPGAs have been widely utilized in the laser electronic control systems due to its high integration and parallel processing capabilities. Based on the classical Ramp-Hold-Fire principle, we develop an injection locking system by using the modular FPGA architecture and the Verilog programming language. To demonstrate the program's viability, Vivado software is utilized for online simulation and debugging to guarantee the correctness of time conversion between different modules. The simulation results show a good time match between the master and slave lasers. The realization of seed injection locking is verified by detecting the increase of output laser energy, shortening pulse setup time and single longitudinal mode output pulse after injection. Finally, a 2 μm single frequency pulse laser is generated with a repetition rate 300 Hz and output power 4.5 mJ.

The role of the ship exhaust infrared suppression system is to control the infrared radiation of the ship exhaust system by reducing the temperature of the ship's chimney wall and exhaust smoke, thereby reducing the probability of the ship being detected by the infrared system. This paper studies the part of the chimney with shutters installed, and uses the fluid calculation software FLUENT to carry out numerical calculations. By simplifying the actual structure, the shutter flow field model is established. The exhaust temperature and infrared radiance of the ship's power system, as well as the structure and characteristics of the flow field, were simulated under the conditions of four different opening areas of the shutter. By analyzing the effect of the opening area of the shutter on the average temperature of the exhaust system, the variation law of the effect of the opening area of the shutter on the infrared radiation characteristics of the chimney is obtained. It is further found that when the opening area of the shutter is 0.6-0.65 of the side wall area, the infrared stealth performance of the ship's power exhaust will have a better effect.

In order to ensure that China's mineral industry can achieve higher benefits and improve work efficiency, mineral enterprises should make dynamic detection and mapping of the geological conditions of mines in time, and take the accurate mapping results as the actual basis in the mining process. Therefore, it is necessary to monitor the complex mine environment, effectively deal with emergencies under the concept of sustainable development strategy, and ensure mine production safety and ecological balance.

Because the near eye display (NED) device mainly displays its imaging effect with a unique virtual image, in essence, compared with the traditional display device, the measurement requirements and methods of brightness, light leakage ratio and other related parameters have also changed. By analyzing the imaging characteristics of optical waveguide AR display equipment, a comparative test scheme for brightness and light leakage ratio is proposed. The same type of arrayed optical waveguide NED module is experimentally measured by using equipment with different test principles, and the measurement results are compared and analyzed. The research results show that the measurement results of the ordinary aiming point luminance meter are not the luminance values in the real display. For the measurement of a certain illumination degree of the equipment, the luminance value and light leakage measured by the aiming point luminance meter have lower deviation than that measured by the two-dimensional imaging luminance meter. Therefore, in the process of testing NED, it is necessary to correctly select the measuring instrument according to its imaging characteristics, the size of the area to be tested and the test scene.

The security camera is widely used. With the long-term aging effect of the environment and the increase in service time, its imaging quality will inevitably decrease. However, there are few research on the impact of environmental aging tests on its imaging quality. This article focuses on the gray scale level of image quality. Considering the complexity of the use environment of the camera, the imaging quality of the typical optical imaging system before and after the gas corrosion testing is analyzed. At the same time, the impact of different light source conditions is also considered here. Studies have found that after environmental testing, the gray scale resolution ability of the imaging system decreases. In addition, light source conditions have a greater impact on its gray scale resolution ability. In the case of optical compensation, the gray scale value is significantly reduced, and the camera cannot perform gray scale resolution. In this paper, two test methods, transmitted standard board method and reflective standard board method, are used to analyze the gray scale value. Studies have found that the results of the two methods are self-consistent.

Aiming at the difficulties of high welding accuracy and weld quality of ultrasonic flowmeter, a high-precision and highquality welding method for pipeline products is proposed. Through simulation analysis of weld thermal deformation, the influence of different welding process parameters on weld thermal deformation is determined, the coaxiality of products and the flatness of installation surface are ensured by designing welding equipment, the starting and ending arc position of pipeline automatic welding is set by adjusting pre-welding assembly quality combined with weld thermal deformation law, and the welding depth and welding quality are ensured by setting welding parameters by sections, thus achieving high precision and high quality of ultrasonic flowmeter. This technology has important practical significance for high-precision and high-quality welding of pipelines.

Aerospace medical on orbit inspection instruments have played a great role in the on orbit health inspection and monitoring of astronauts because of their high detection accuracy, portable use and strong environmental adaptability. This paper briefly describes the main detection methods of on orbit medical detection instruments, including electrochemical method, dry chemistry method, flow cytometry combined with fluorescence detection technology, chemiluminescence immunoassay technology and enhanced Raman spectroscopy. The application direction and current situation of on orbit precision detection instruments in the field of aerospace medicine are introduced, and their future development trends are prospected.

The phase unwrapping method is the important step of phase retrieval in fringe projection profilometry. Although the mask cut (MC) algorithm has been successfully applied in multiple fields, it also has inherent flaws. In order to overcome the shortcomings of MC algorithm, and synthesize the advantages of MC and quality-guided (QG) algorithm, a quality-guided mask-cutting (QG - MC) algorithm for phase unwrapping is proposed. The basic idea of QG - MC algorithm is to reduce the effects of noise on phase unwrapping at first., Then, the process of phase unwrapping is guided by the phase quality map from the point with the highest quality value to the point around that point. Take the point with the highest quality as the seed point, put its adjacent points into the queue, sort by quality value, and the new highest quality point is used as a seed point. Repeats the process until the queue is empty and the unwrapped phase will be obtained. To verify the feasibility and reliability of QG - MC algorithm, computer simulations and real experiments are carried out. The results show that the algorithm improves the efficiency of phase unwrapping.

In the field of industrial automation, accurate acquisition of object three-dimensional information is beneficial to better product design. Structured light three-dimensional measurement technique has been widely used in industrial inspection and reverse engineering because of its advantages of non-contact and high measurement accuracy. The structured light three-dimensional measurement technique combined with gray code and phase shift method has high efficiency and strong robustness. However, in the process of extract the phase map of the measured objects, there will be misalignment between the wrapped phase and the fringe order. This will lead to the jump error of wrapping phase edge in phase unwrapping process, which will reduce the measurement accuracy. To solve this problem, the fast tripartite phase unwrapping method is proposed in this paper, which can effectively eliminate the phase unwrapping error and significantly improve the computational efficiency. Firstly, the mask image is obtained by threshold segmentation of full-bright images using OTSU method. Subsequently, phase unwrapping is carried out under the guidance of gray code coding sequence, and the absolute phase value of the target is obtained. In the process of phase unwrapping, the mask image is used as the guide to improve the phase decoding efficiency, and tripartite phase unwrapping method is used to eliminate the phase unwrapping error. Experimental results show that this algorithm eliminates the edge jump error and improves the efficiency of normal gray code phase unwrapping method.

Sialon ceramic tool material has excellent mechanical properties and high temperature resistance, which is one of the most potential tool materials at present, and it has been widely used in the machining of Inconel 718 superalloy. It is of great value to discuss the high-speed cutting of superalloy Inconel 718. Therefore, it is necessary to clarify the wear principle and cutting performance of Sialon ceramic tool during high-speed cutting of superalloy Inconel 718, so as to ensure the overall cutting quality and prolong the service life of the tool. Based on this, this paper introduces the basic situation of Sialon series materials, and discusses the wear principle and cutting performance of Sialon during high-speed cutting of superalloy Inconel 718 from the aspects of tool service time, cutting force and surface roughness by means of experiments, so as to provide reference for high-speed cutting of superalloy Inconel 718 in China.

Under the dual effects of the growing demand for efficient distribution and the normalized management of the epidemic, the application of intelligent robots in the intelligent distribution process is considered. In order to let the robot choose the optimal path to reach the target point, and at the same time in each movement process, the obtained detection data are real and reliable. In this paper, combined with the characteristics of the robot itself, the ant colony algorithm is applied, and the detection data is processed through the BP neural network. Using MATLAB simulation platform to generate a twodimensional map randomly, the simulation experiment is carried out. The simulation experiment shows that the proposed algorithm has achieved good results.

In order to analyze the noise spectrum of converter substation and control the occupational exposure noise of operators at an acceptable level, this paper makes field measurement and spectrum analysis of occupational exposure noise of converter transformers, converter valve halls, AC filters and other operators in converter substations with different voltage levels. The results show that the noise energy of converter substation is mainly concentrated in the middle and low frequencies, and the sound pressure level of the line spectrum with even frequency doubling of 50Hz is prominent, and the frequency is concentrated in the frequency range of 100 ~ 1000 Hz. Except that the energy of the valve hall is still high at the high frequency, the sound pressure level of noise in other workplaces almost drops below 50dB when the frequency is higher than 5kHz. Based on this feature, noise control measures are put forward from three aspects: sound source control, sound insulation control and personnel protection.

In this paper, we design and theoretically simulate a highly sensitive photonic crystal fiber sensor based on lossy mode resonance. An ITO/HfO₂ bilayer was coated onto the exposed area of the fiber core as the sensing material. This asymmetrical structure can lead both TM-and TE-polarization to improve the detection performance. In addition, we further investigated the influence of the ratio of ITO/HfO₂ bilayer film thickness on the maximum sensitivity of the proposed sensor and finally reached a maximum sensitivity at 1.92nm/1% for glycerol solutions detection, which plays a significant role in the optical fiber sensor in the field of glycerol detection.

Ethanol has a characteristic narrow band absorption peak (2989.6 cm^-1) that overlaps heavily with the airborne water vapour spectrum, severely affecting detection accuracy when the ambient humidity varies significantly. To this end it is particularly critical to investigate a method to eliminate background effects and improve the accuracy of ethanol telemetry. Firstly, the second harmonic signal of ethanol concentration under 5000~20000ppm*m water vapour environment was simulated by multi-functional fitting method, and the multivariate linear relationship between the second harmonic amplitude and water vapour concentration and ethanol concentration is obtained. Two sets of signals were obtained in one triangular wave period using double modulated amplitude and linear regression was used to solve the coefficients of the two equations, which in turn inverted the ethanol concentration in other water vapour environments. Simulation results show that the maximum error is less than 2.23ppm*m. The method also eliminates the need for complex reference light paths or expensive wide-range tunable mid-infrared lasers, reduces measurement errors due to variations in ambient humidity, and provides a basis for further development of simple, miniaturised ethanol telemetry systems.

This paper mainly discusses the underwater fog technology, and mainly uses some image evaluation algorithms. Compared with other image processing algorithms, it improves the running speed of the algorithm. In short, the underwater image denoising and contrast after processing are better than the traditional image polarization defogging algorithm. The experiment specifically uses the split focus plane polarization imaging system to collect polarization pictures from multiple angles in multiple underwater scenes, and calculate its polarization stokes vector, calculate the polarization information of the scene through the stokes vector, use the general light source and linear polarization light source to illuminate the diffuse reflection and specular reflection targets respectively, compare the polarization information of different scenes, and get that the polarization information distribution of the background and target of the scene using polarization light source is clearer than that of the general light source. Then, a stokes polarization defogging algorithm is proposed. The polarization degree information calculated by stokes vector is compared with the transmission information obtained by the dark channel prior algorithm. It is found that under the condition of using polarized light source and uniform illumination, the transmission of scene can be predicted by DOP (Degree of polarization) calculated by stokes vector and used for image defogging, then some image evaluation algorithms are used to compare it with other image processing algorithms, which improves the running speed of the algorithm. The denoising and contrast of the underwater image after processing are better than the traditional image polarization defogging algorithm.

H₂O is an important molecule in the atmosphere, which is closely related to climate change and industrial applications (such as combustion process). The detection of trace water vapor concentration is of great significance in earth ecology and industrial production. Tunable diode laser absorption spectroscopy (TDLAS) inverses the gas concentration by measuring the gas absorption spectrum. The wavelength of the common characteristic absorption peak of H₂O molecule is 7181.16 cm-¹. The spectral absorption peaks of different wavelengths are analyzed in the paper. It is proved that when 7306.75 cm^-1 characteristic absorption peak is used to replace 7181.16 cm^-1 characteristic absorption peak for concentration inversion, the influence can be reduced and the measurement accuracy can be improved by combining the target peak with the interference peak.

Aiming to fulfill the need for noise monitoring of a power grid, a self-powered system was established in this study for noise monitoring sensors of power equipment. Specifically, the self-powered system is a wireless vibrational energy transduction and storage system that has low power consumption and does not require a power supply. It includes a transducer module, a circuit conditioning module, and an energy storage module. In particular, the piezoelectric sheet was designed based on the vibration characteristics of power equipment and a zinc oxide nanowire array was selected as the material of the transducer module, which converts vibrational power used by the power equipment into electrical energy. An LTC 3588-1 chip was adopted for the circuit conditioning module to rectify the electrical energy collected. Meanwhile, lithium batteries were employed for the energy storage module. Through preliminary experimental research, the system demonstrates good energy transduction and storage functions. Regarding the technical characteristics of this self-powered system, the respective installation and maintenance are convenient. Further, such vibrational energy harvesting technology uses the vibration of the power equipment itself as an energy source; thus, it has potential in applications in which obtaining light energy and replacing batteries are difficult.

Algorithms for locating the center position of the crosshair image are studied, and a method based on machine vision to verify the compensation error of automatic levels is proposed. An illumination device is added behind the reticle of the automatic level. The reticle image is focused to infinity, imaged on the focal plane of the lens of the collimator, and images are captured using a CCD camera. Moreover, the necessary processing is performed to locate the center position of the crosshair image by the gray squared center of gravity method and the iterative weighted fitting method to obtain the subpixel level position coordinates. The metrological verification of the compensation error is completed after calibrating the angular grid values of the CCD in the x and y directions, the error angles of the x and y axes, and the parameters of the collimator coordinate system and attitude. The experimental results show that the machine vision-based method meets the requirements of the metrological verification of the compensation error of automatic levels, and the accuracy of the measurement results is higher than the traditional optical method.

The calibration accuracy of inertial measurement unit (IMU) is one of the important factors affecting the positioning accuracy of strapdown inertial navigation system (SINS). A 24-sequence calibration rotation scheme is proposed in this paper, which improves the observability and observability degree compared with the traditional 18-sequence scheme, and makes the calibration results more accurate. Simulation results show that the calibration results of 24-sequence scheme are closer to the actual value than those of 18-sequence scheme.

In this paper, the five-sensor magnetic gradient tensor system is taken as the research object, and the alignment error correction is studied. Firstly, a single sensor error model is established. Secondly, the overall error model is established. Finally, the proposed method is verified by simulation. The simulation results show that the proposed correction method can effectively reduce the alignment error of the system.

There are many kinds of infrared detection system operating range evaluation models and their parameters are complex, which result in the lacking of evidence for model selection in practical application. To solve this problem, the adaptability of four common operating range models of infrared detection system are analyzed. Using theoretical and simulation analysis, the defects of traditional model, NETD based model and SNR based model in practical application are pointed out, and the model based on NEP is selected as the operating range evaluation model of airborne infrared detection system. Then an operating range evaluation system is developed to provide reference and evidence for model selection in practical application.

Forest canopy structure is an important parameter for measuring forest changes and forest coverages. It is significant to explore the application of TerraSAR-X/TanDEM-X data in tree height inversion. In this research, the phase difference-phase coherence magnitude algorithm and the digital elevation model (DEM) method were investigated based on the random-volume-over-ground (RVoG) model. With Mengla County in Xishuangbanna Dai Autonomous Prefecture in Yunnan Province as the research area, the forest height inversion was performed based on TerraSAR-X/TanDEM-X data. Finally, the results were verified by combining field-measured data. For natural forests and rubber plantations, the DEM height difference method magnitude tree height inversion algorithm improves the estimation of the earth phase and canopy phase favorably, while the traditional algorithm presents a high height inversion precision for rubber plantations.

To further investigate the failure process of concrete in demolition blasting, the concrete blasting experiments were conducted. The digital image correlation (DIC) method was used to measure the full field surface deformation. In the DIC method, the surface fitting sub-pixel displacement algorithm has simple structure and high computational efficiency, however, the accuracy is poor. A new surface fitting algorithm based on moving least square method with a Gaussian basis function and a 3×3 fitting window was used and the accuracy was improved to 1/200 pixel. The blasting experiment results show that the failure of concrete is driven by blasting stress wave and gas. The action time is about 4.5 ms. The formation of crack is dominated by stress wave. The maximum velocity of crack propagation is 225.95 m/s, the average velocity is 122.27 m/s, and the time is about 1.75 ms. The gas mainly makes the crack to expand, and then divides the concrete. Under explosion loading, the concrete also shows a fracture process zone, and a strain concentration is formed at the crack tip. The length of the fracture process zone is 8~9 times of the maximum aggregate size.

In the process of aligning and assembling prefabricated segmental beams, the measurement method of using total station to obtain spatial pose has the problems of high manual dependence, low measurement efficiency and high construction risk. The existing non-contact measurement methods are analyzed. It is concluded that photogrammetry has the conditions to realize automatic measurement and can reduce certain construction risks. According to the complex situation of bridge construction site and the harsh environment, traditional camera calibration methods are not applicable. Therefore, a self-calibration method is proposed. At the same time, according to the self-calibration algorithm, all photos taken cannot be solved, and there are problems of photo redundancy. The algorithm is further optimized to obtain a focal length calibration method based on global scanning, and the camera shooting is used to test and verify the construction site of prefabricated segmental beam assembly to explore whether the measurement accuracy of the method can meet the construction requirements in the actual construction environment. The results show that the measurement method can be realized in the construction environment of precast segmental beams. And the measurement accuracy meets the assembly requirements of precast segmental beams.

When two aircraft interact in an aerial refueling operation (confluence, pre-docking, docking and separation), it is challenging for pilots alone to control the distance and speed between the two aircrafts. Based on GPS dynamic differential equipment, this paper studies the relative positioning algorithm that measures the relative position between the refueling probe and drogue, forming a unified coordinate system of the moving space platform. This method builds a high-precision, stable and reliable two-machine relative position measurement special system and provides auxiliary guidance and safety warning for the aerial refueling process.

Under the background of information technology, virtual reality technology has gradually been applied to the field of education and training. Immersive VR can promote the progress of university education, realize the transformation of university education from two-dimensional flat teaching to three-dimensional three-dimensional teaching, and enhance the situational and contextual nature of classroom teaching. Interactivity. The application of VR technology in education can effectively improve the learning effect and enthusiasm of students. Students can independently choose their own learning time, learning location, and learning style, with stronger learning motivation and higher autonomy. This article is based on the establishment of an immersive interactive teaching platform and a teaching resource library so that users can better enter the learning atmosphere.

Magnetic gradient tensor detection is suitable for geological exploration, target location and many other fields. Among the commonly used magnetic gradient tensors, the third-order magnetic gradient tensor has higher resolution and can obtain more and more magnetic source information. But its stability is poor. It will lead to a large error under the condition of noise. Aiming at the above shortcomings, this paper puts forward an improved method. The approximate calculation formula of the third-order magnetic gradient tensor is analyzed and improved. It can be concluded from the simulation results that the improved method is more stable.

A motion state model set for maneuvering target has been established to solve the problem of the increased trajectory measurement error in the maneuvering process of aerial vehicle. The low accuracy of filter caused by the incomplete description of motion state for the single model has been solved by utilizing the interacting multiple model (IMM) algorithm. The adaptive factor has been introduced to the Unscented Kalman Filter (UFK) to resolve the inaccurate observation error prior by adjusting the process noise covariance matrix in real time. The adaptive probability conversion factor based on compression ratio has been added to the IMM algorithm, enhancing its convergence rate. At last, a new AIMM-AUKF trajectory measurement filter algorithm has been formed so that the high accuracy measurement for the trajectory of random maneuvering target has been achieved and the validity the proposed algorithm has been verified through simulation.

Electrical importance tomography (EIT) is a non-invasive technique that aims at reconstructing the internal tissue image of the human body. In this paper, the application of EIT technology in pressure equipment flaw detection is experimentally studied. This paper mainly studies the feasibility of applying EIT technology to temperature monitoring and location, pressure damage location and surface crack defect location. The results show that this method can better detect and locate damage.