In order to improve the laser welding quality, laser welding experiments were carried out, in which the 1CR13 specimens were treated by varied power of ultrasonic vibration. By the test of microstructures of welding joints grains, the effects of ultrasonic vibration on laser welding process were studied, some results were found that the growth of the columnar crystal grain was affected, with the growth of the ultrasonic vibration power the grain was refined. According to the metal solidification theory and ultrasonic vibration cavatition theory, we can conclude that the ultrasonic vibration cavatition causes the fall of temperature of micro zone and partial high pressure in the welding molten bath, which increasing the driving force of melt crystallization and reducing solidification activation energy, increasing the melt nucleation rate.

Nanosecond pulse laser was used to lap weld 316 stainless steel with 0.2 mm thickness, then was used to scan modified the appearance of spots. Through orthogonal experiment for laser scanning process parameters, it was known that when laser power was 25 W, pulse frequency was 600 kHz, scaning speed was 1 500 mm/s, residual height of spots was 28.7 μm, and appearance of spots were not yellowing and blackening, which met requirements of production. Cross section analyzed results showed that after laser scanning, oxide layer produced during welding was removed, residual height of spots was decreased, and appearance was been changed to no yellow, no black.

In order to study the characteristics of porosity formation of mild steel under two conditions of penetration and non-penetration, mild steel (6 mm and 8 mm thick) was welded with a welding power of 3 100 W and a welding speed of 10mm/s, respectively, under the control of two parameters which is shielding gas and surface oxide. The method of cutting cross-section of weld seam was observe the morphology and location of porosity in the weld by scanning electron microscope(SEM).EDS point scanning analysis in the wall of porosity and discuss the causes of porosity formation. In addition, the permeability experiment was designed to study the influence of laser power and welding speed on the porosity. The research results show that the number and rate of porosity in the condition of penetration are far less than those in the condition of non-penetration. The shielding gas of CO2 and the surface oxides can inhibit the pores in the welding process. Under the condition of non-penetration, the porosity formation in the weld are metallurgical pores and process pores. But in the condition of penetration, the pores of the weld are round H2 pores. The content of chemical elements of metallurgical pores in the porosity and weld zone is greatly different, which is mainly caused by metallurgical reaction in the molten pool. Moreover, The higher the laser power, the less the number of porosity, but the rate of porosity first decreased and then increased. With the increase of weld velocity, the number of porosity increased, but the rate of porosity decreased first and then increased.

In order to verify that laser welding meets the generator shell connection requirements, a fiber laser welding test system was developed, and the airbag gas generator shell welding process was optimized by using a 2 500 W laser and LDD laser welding whole process monitoring system. The water burst pressure test and visual inspection test of the high-strength low-alloy carbon steel generator shell have been carried out. The results show that when the laser power is 1 400~1 500 W, the water burst pressure value of the DAB5 series gas generator shell reaches 66 MPa. There is cracking phenomenon, the welding strength is greater than 60 MPa, the penetration depth is within 2~3 mm, the eccentricity of the weld is 0~0.2 mm, and the effective melting width is 0.5~0.8 mm, which all meet the index requirements.

The bottom-locking joint laser welding experiments between titanium alloy TA15 plate with a thickness of 1.8 mm and ZTA15 as-cast conditions with a thickness of (1.8+1.8) mm were carried out by disk laser. The internal quality and microstructure of the welded joints were observed by using X-ray diffraction and metallurgical microscopy, respectively. Mechanical properties of laser welding of bottom-locking joint was also evaluated. The tensile fracture of the bottom-locking joint was analyzed by scanning electron microscope. The results show that good internal quality and forming with the appearance of sliver and white weld can be obtained when welded with reasonable welding parameters. The excellent mechanical properties of the bottom-locking joint can be also obtained in the meantime. The microstructures in the center of weld seam and heat affected zone are composed of slender acicular martensite α′+ α-phase+β-phase. The tensile fracture site of bottom-locking joint mainly appears in the weld seam area. The titanium alloy laser welded joints show a mixture of ductile and brittle fracture after tensile test.

In this paper, through the laser cladding experiments of pure Co powder mixed with WC particles of different sizes and proportions under different technological equipment and parameters and cladding effect detection, it proved that the semiconductor laser with large fiber core diameter and large light spot is more suitable for metal based cemented carbide cladding. By reducing the energy concentration of the spot and reducing the input power to reduce the heat input, and increasing the WC particle size to reduce the thermal sensitivity of the WC particles, which can effectively inhibit the dissolution and decomposition of WC, and reduce the number and size of pores in the cladding layer. The cracking tendency of the cladding layer can be reduced by substrate preheating or full Ar protection. A large area of laser cladding WC-Co cemented carbide coating with a WC mass fraction of 60%, no cracking, and low porosity can be obtained under full Ar protection conditions, using input power 800 W, scanning speed 4 mm/s, powder feeding rate 11 Hz, or under substrate preheating 400-450 ℃ conditions, using input power 800 W, scanning speed 7 mm/s, powder feeding rate 11 Hz.

In order to understand the influence of process parameters and shape parameters on the forming accuracy of laser selective melting parts, a mathematical model was established for the dimension error in height direction and the shape error of arc surface.The orthogonal experiment of laser selective melting was carried out with 316L powder on the basis of printing layer thickness of 200 μm，five factors and four levels including laser filling power, laser contour power, scanning speed, shape parameters and scanning distance were selected for the experiment. The experimental results show that the influence factor of surface roughness is laser power, and the roughness value decreases with the increase of laser power；the influence factors of profile error are shape parameters and filling laser power. There is the worst center angle, and the profile error increases with the increase of laser power. The influence factor of dimension error in height direction is mainly the structure of the part itself, and the influence of processing technology on dimension error is not significant. This study provides a theoretical and experimental basis for the accuracy analysis of laser selective melting 316 parts.

In order to improve the defects of low hardness and poor wear resistance of titanium alloy (TC4) parts, B4C/Cobalt-based alloy composite coating was prepared on TC4 surface by laser cladding technology. The temperature field of the composite coating was numerically simulated by finite element method, and the influence of laser power on the single laser cladding of B4C/Cobalt-based composite coating was studied by the combination of surface morphologies and micro-hardness. The results show that the peak temperature and depth of molten pool increases with the increase of laser power, whereas the width of molten pool almost has no change. When the laser power is 1 600 W, the micro-hardness of the composite coating reaches the highest value of 618.7 HV(2 N loading force), which is 79.2% higher than that of TC4 substrate, and the strengthening mechanism of B4C is revealed.

The horizontal overhang is a special overhang structure, and it is also a problem with selective laser melting (SLM) molding technology. This paper studies the relationship between the forming characteristics of the first-layer surface profile features and the forming quality at different laser powers by image processing. The results show that there are bright spots and pores of different sizes on the surface of the first layer by using the “Meander” scanning strategy, which have an angle with the scanning direction and change with the input of laser energy; when the laser power is decrease, the pores on the surface of the layer are enlarged, and the bonding strength between melt tracks becomes lower. The scanning strategy of "rotary" remelting can improve the ability of the first layer to resist external force deformation, and effectively avoid the warping deformation and collapse of the forming surface.

The rapid melting and solidification of metal powder in selective laser melting process will produce a large thermal gradient, and the dynamic change of temperature gradient will affect the microstructure and mechanical properties of different powder forming parts. Based on finite element analysis software, three-dimensional transient temperature field of selective laser melting forming process was simulated by using moving Gaussian heat source (Gauss) loading. The different properties, temperature changes and solidification cooling laws of Hastelloy X and Ti6Al4V alloys were studied. At the same time, Hastelloy X and Ti6Al4V alloy samples were prepared by selective laser melting process, and their microstructure and mechanical properties were characterized. The results show that the transient peak temperatures of Hastelloy X and Ti6Al4V alloys reach 2 777.37 ℃ and 3 340.88 ℃, and the average cooling rates are 3.93×106 K/s and 5.11×106 K/s, respectively. In the micro-state, grains of Hastelloy X alloy are arranged in feather-like lamination and cross-arrangement, while needle martensite α′ phases are distributed in Ti6Al4V alloy to form a net basket structure. Compared with 728.08 MPa and 338.91 MPa of tensile strength and yield strength of Hastelloy X alloy, the tensile strength and yield strength of Ti6Al4V alloy with "fine grain strengthening" effect at high cooling rate reach 1 134.05 MPa and 1 055.83 MPa, which are much higher than that of Hastelloy X alloy, but its elongation is lower than that of Hastelloy X alloy, which is generally characterized by high strength and low plasticity.

The Co-based alloy coating was prepared by laser cladding on GCr15 bearing steel with fiber laser. The effects of laser power, scanning speed and powder feeding rate on the dilution ratio of the coating were studied by orthogonal experiment. According to the results of orthogonal test, RBF neural network was used to establish the prediction model between the laser process parameters and the dilution rate of cladding layer, then the network was tested with test samples. The results show that the most significant factor affecting the dilution rate is the powder feeding rate. Due to the energy threshold and "heat shield" effect of powder melting, the dilution rate does not increase or decrease with the increase of laser power and powder feeding rate, there are some fluctuations；With the increase of scanning speed, the dilution ratio decreases gradually, and the variation of dilution ratio is determined by the interaction of various cladding process parameters. The RBF neural network model trained by the experimental data can predict the dilution ratio of the Co-based cladding layer prepared under different laser processing parameters. The relative error between the predicted value and the measured value is within 6%, which has a high prediction ability.

Ultra-high-speed laser cladding technology replaces chromium plating, which can solve the industrial application problem of heavy metal pollution caused by chromium ion (Cr6+) in chromium plating process. Hard chromium plating on the surface of metal workpiece is a combination of corrosion resistance protection and decoration, which has a great application prospect.Hard chromium plating on the surface of metal workpiece is a combination of corrosion resistance protection and decoration, which has a great application prospect.The research and development of ultra-high speed laser cladding technology in China mainly focuses on equipment integration and process experiment research, but lacks the simulation model of cladding process.In this paper, the ultra-high speed laser cladding ring cladding head is taken as the research object, and a CFD simulation model based on unsteady particle tracking technology is established by using FLUENT, and a temperature field model of laser cladding powder for ring cladding head is developed.The ultra-high speed laser cladding process is tested and analyzed. The theoretical model of the process is established.Through simulation results, it is found that powder spots with a radius of 0.8 mm can be formed by ultra-high speed laser cladding ring cladding head, and the powder concentration is the highest in the space of 15 mm~19 mm below the cladding head. The feasibility of the model is verified by experimental comparison.

A repair method of rapid cladding and remelting on automobile transmission shaft material is proposed. The composite material of 316L stainless steel powder and nano SiC particles is used as the cladding powder. The porosity, microstructure, phase, hardness, residual stress and tensile strength of the repair layer are studied by experimental characterization. The results show that the porosity decreases from the bottom to the top of the repair layer, which is mainly composed of fine dendrite and cellular crystal, and the phase composition contains γ-CrFeNi、M7C3、FeSi、SiC. Besides, the average microhardness was 577 9.5 HV. Each layer of the cladding has been remelted synchronously, and most of the stress is released to form residual compressive stress. The average tensile strength, elasticity modulus and elongation are 835.5 MPa ± 22.0 MPa, 110.6 GPa± 17.0 GPa and 25.3% ± 0.6%, respectively.

In this paper, experimental investigation on 1 kW fiber laser cutting carbon fiber composite materials is carried out. The influence of laser power, cutting speed, and assistant gas pressure on the slit width, the heat-affected zone and the slit taper is studied using single factor method. Orthogonal experiments are used to study the main factor that affect the width of the slit and the width of the heat-affected zone. The results show that the slit width, notch taper and heat-affected zone increase with the increasing of laser power. With the cutting speed increasing, the width of the slit and the heat-affected zone decreased, and the notch taper increased first and then decreased. With the increase of the assistant gas pressure, the slit width and the taper of the incision increased, and the width of the heat affected zone decreased. When the laser power, the cutting speed, and the assistant gas pressure is 100 W, 1 m/min, and 0.5 MPa respectively, the cutting quality is better, and the cutting efficiency is higher.

In order to obtain the best technological parameters for laser cutting of 304 stainless steel with a thickness of 3 mm, a laser cutting machine with a power of 3 kW was used for laser cutting experiment. A four-factor and three-level orthogonal experiment scheme was designed to study the effects of laser power, cutting speed, oxygen pressure and defocusing amount on laser cutting quality. Through poor analysis to explore the weight of each factor on laser cutting quality, and then by the orthogonal experiment data, a BP neural network prediction model was set up and use method of combining the BP neural network and genetic algorithm to find the best parameter combination. Comprehensive optimization to obtain the optimal process parameters of laser cutting quality, the laser power is 750 W, the cutting speed is 2 000 mm/min, oxygen pressure is 0.5 MPa, and the coke is +2 mm. The test results show that the optimized specimen has smooth cutting surface, small roughness and slit width, and meets the expected requirements.

In this study, the effects of process parameters such as power, filling intervals and repetition rate on the surface roughness of aluminum alloy (2024) were studied in order to analyze the law of influence between process parameters and roughness from the aspects of morphology and product composition. Firstly, 1 060 nm MOPA laser was used to mark aluminum alloy 2024, and then the surface roughness of the mark was measured by roughness detector under different process parameters, and the results show that power, filling interval and repetition rate affect the melting, gasification and recasting degree of the material surface, resulting in different surface roughness and different roughness variation rules. The surface morphology of the marking area was observed by digital microscope system, and the chemical composition of the marking area surface was analyzed by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The results show that the melting, vaporization and recasting degree of the marking area surface are obviously different with different process parameters, so the surface morphology and products affect the surface roughness of the marking area.

Powder transportation is the main factor affecting the morphology of the laser cladding layer of the coaxial powder feeding nozzle. In order to improve the concentration effect of the powder flow in the flow field outside the nozzle and study the influence of the elastic recovery coefficient on the powder flow, this paper combines the existing four-channel coaxial powder feeding nozzle in the laboratory to establish a three-dimensional simplified model based on the gas-solid two-phase flow theory the velocity field, concentration field, focal length, and spot size under different elastic recovery coefficients are simulated and calculated by Fluent software. Numerical simulation results show that when the carrier gas flow rate and powder feeding rate are constant, with the increase of the elastic recovery coefficient, the powder flow velocity increases slightly, and the air flow velocity changes little, the concentration and focal length of the convergence point decrease, the powder flow converges increase.

In this paper, an experimental study of the picosecond pulsed laser processing with constant single pulse energy, different filling distance and processing times was carried out on Co-WC binary cemented carbide with WC particle size of 0.7-0.8 μm and mass fraction of 91.5%-92.0%. It is found that in the range of the filling distance smaller than the light spot width, the filling distance increases, and the processed surface presents a finishing effect with reduced surface roughness, the filling distance decreases, the laser ablation effect on the material increases; the more processing times, the greater the depth of material removal; with the increase of processing times, the surface of the material is passivated and deactivated, and the ablation effect of the laser weakens; through the detection of the residual stress in the laser processing area, it is found that the picosecond laser processing has no obvious effect on the residual stress on the surface of the cemented carbide; pulse laser edge grinding is performed on the secondary cutting edge of the cemented carbide drill, which removes the residual micro-notches of grinding wheel, and obtains better edge quality and rake surface quality.

Titanium alloy possess outstanding comprehensive properties, and they are important metal structural materials which have been widely used in aerospace industry, chemical industry, marine engineering and other fields. This study adopts laser melting deposition (LMD) technique to prepare TC4 titanium alloy, and mainly focuses on the study of optimal optical powder matching for forming equipment. As a result, a method for optimizing the processing parameters of forming was established, which based on such constraints like macro profile of cladding layer, dilution rate, shape coefficient, etc. Moreover, this study determines the optimum range of overlapping ratio through establishing critical lap rate model of cladding layer and conducting a single factor experiment. The optimal combination of processing parameters was used to form TC4 titanium alloy and its structure and properties were evaluated. The result shows that the low-magnification structure of TC4 titanium alloy as deposited is mainly composed of epitaxially grown coarse β columnar crystals and continuous intergranular α phase. The intragranular structure is mainly acicular martensite α phase, and granular secondary α phase dispersed in the microstructure under SEM. The microhardness and elongation in longitudinal of sediment state are slightly greater than that in transverse, nevertheless, the transverse tensile strength and yield strength are both higher than that in longitudinal state. The transverse tensile fracture is characterized by intergranular fracture and the longitudinal tensile fracture is characterized by plastic fracture. The sediment state of TC4 titanium alloy formed by optimized processing parameters is superior to the mechanical properties stipulated in SAE AMS 4999A standard.

In selective laser melting (SLM) additive manufacturing, the high thermal stress induced by the high temperature gradient causes the deformation of the parts, which seriously affects the dimensional accuracy of SLM parts and has become the main obstacle to its engineering application. In the study, a large-scale thermo-mechanical indirect coupling finite element numerical model is developed to study the deformation distribution of the typical parts fabricated by SLM. The results indicate that the typical parts, such as the thin-walled part, incline-walled part, block, cylinder, and tri-prism, show an internal concave deformation. The maximum deformation occurs at the middle of the side of the parts. The simulated deformation results are in good agreement with the experimental data, and the error is less than ± 20 μm. The results provide the theoretical guidance for the deformation and accuracy control in SLM.

In order to study the effect of laser direct part marking (DPM) on the mechanical properties of aluminum alloy 2024, the marking depth, microhardness, static tensile test and high cycle fatigue test were carried out on the marked aluminum alloy 2024. The results show that the marking depth varies greatly under different process parameters, ranging from 5.26 μm to 525.7 μm; recast zone will be formed in the marking area, and the microhardness is 51-62 HV, which is significantly less than the microhardness value of the material matrix; the marking depth will affect the tensile properties and fatigue properties of aluminum alloy 2024, and the tensile properties of aluminum alloy 2024 after marking at a certain marking depth will be improved The energy and fatigue properties are equivalent to the tensile and fatigue properties of normal materials.

Aiming at the laser cleaning of petrochemical equipment, firstly, the laser cleaning process for black skin of stainless steel weldment is studied by building a process platform, and the process parameters of the best cleaning effect and the most efficient cleaning process were obtained. Secondly, tensile and bending test of the stainless steel weldment with excessive laser cleaning, normal laser cleaning and without cleaning were carried out. The ultimate tensile strength of the stainless steel weldment with excessive laser cleaning exceeded the value in the standard by 17.3%, and no cracks were found on the surface of the welding area and the heat affected zone in the bending test, which means that all specimens are accord with NB/T47016-2011 “Mechanical property tests of product welded test coupons for pressure equipment”. It is proved that static strength mechanical properties of welding area of petrochemical equipment with laser cleaning meets the engineering requirements, indicating that laser cleaning is a safe cleaning method. Finally, through the situ laser cleaning test, the cleaning effect and cleaning efficiency is considered, and the advantages of selective laser cleaning, small damage and good accessibility are also taken into account, the recommended level of laser cleaning on various occasions of petrochemical equipment is proposed, which provides a reference for the application of laser cleaning technology in the petrochemical field.

As an advanced processing method, laser is widely used in cutting and modifying of wood materials, which could significantly improve the processing efficiency and product performance. In this study, the bamboo inner layer was irradiated by CO2 laser, and the laser power, moving speed and moving path distance were selected as input variables to explore the effects of laser modification parameters on the color changes and created the prediction models for color difference. The results showed that the total color difference of bamboo inner layer increased with the increased of laser power, but decreased with the increased of moving speed and moving path distance. The brightness values showed a downward trend, and the surface color of bamboo inner layer became darker after laser treatment, the absolute value of brightness difference also increased with the enhancement of laser power, and decreased with the increased of moving speed and moving path distance. After laser treatment, the maximum value of total color difference was 19.9, and the value of brightness decreased 16.2. The values of R2 of quadratic prediction models for total color difference and brightness were 0.981 1 and 0.984 3, respectively. It meant these two models had good prediction. After laser treatment, bamboo inner layer can present different color such as light yellow and yellowish brown, which enriches the visual effect of the bamboo materials.

The optical parametric oscillator (OPO) is a simple and effective method to generate desirable and specific wavelength. The OPO laser is small, portable and has high efficiency, low threshold and can be operated at room temperature. In this paper, we report an electrically controlled tunable optical parametric oscillator operating from wavelength of 2.97 to 6.35 μm. The nanosecond OPO is based on BaGa4Se7 crystal and pumped by a 10 ns 1.06 μm electro-optic Q-switched Nd:YAG laser. The output mid-infrared idler wave can be tuned from 2.97 μm to 6.35 μm with pulse energy as high as 1.97 mJ at 3.8 μm and can be even increased with more pump power. The central idler wavelength is 4.66 μm (rotation angle is 0°). The output idler wavelength can be tuned by turning the rotation angle of the crystal, which is controlled by an electronic motor. The motorized continuous rotation stage is compact and highly precise with minimum rotation step of 0.002 5°. This enables the fine tuning of the phase-matching angel and the resulting output wavelength.

Based on the requirement of laser adjustment system for power supply output voltage accuracy and ripple, the paper proposed a circuit scheme for synchronous adjustment of positive and negative output voltage, designed a voltage regulator circuit controlled by a mirror current source and a power supply prototype for debugging. The power supply that was a simple structure, realized a high-precision voltage adjustment function with low ripple and met the requirement of laser adjustment system. The test result showed that the designed power supply achieved high-precision adjustable and low ripple output below 5 mV, met the requirements of laser trimming system for power supply.

Photovoltaic cells as an important part of the national "dual carbon strategy", the improvement of its conversion efficiency is of great significance. Aiming at the invalid conversion area of crystalline silicon and other solar cells, this paper designs and prepares microstructure light-enhanced films based on the principle of total reflection. The microstructure of the film is triangular groove orthogonal grating with period and groove depth of 80 μm. The test results of photovoltaic cell modules fitted with thin film samples show that the conversion efficiency of the three groups of modules is increased by more than 2%. Compared with other methods to improve the efficiency of photovoltaic cells, this method is simple and feasible, and is expected to be widely used in photovoltaic cell modules, and contribute to our country′s "dual carbon strategy".

For improving the efficiency of single-beam laser processing QR code, a parallel processing method based on spatial light modulator is proposed. The GS algorithm is used to generate a two-dimensional code multi-beam hologram with high beam uniformity, combined with a spatial light modulator and femtosecond laser to mark a QR code that can be effectively identified on the stainless steel surface. The effects of single pulse energy, pulse number, defocus amount and beam uniformity on the processing quality of QR codes are studied, and the optimal parallel processing parameters of QR codes are obtained through experiments.

The three-dimensional calibration of the line structured light measurement system is a necessary part of the three-dimensional measurement. Its calibration accuracy directly determines the accuracy of the three-dimensional measurement. The calculation process for the current line structure cursor positioning is complicated, limited, high cost, low precision, etc. Problem, this paper proposes a direct calibration method of spatial high-precision line structured light. Design a special-shaped calibration block, remove the noise points and boundary points on the line laser stripe of the calibration block through the DBSCAN algorithm, then use the improved PSO algorithm to optimize the objective function of the shortest path optimization, extract the characteristic calibration points on the line laser stripe, and establish the pixel coordinates The mapping relationship table with the world coordinates, so as to directly obtain the world coordinates corresponding to the pixel coordinates of the point to be calibrated, or calculate the relationship conversion matrix through the three characteristic calibration points closest to the point to be calibrated to obtain the world coordinates of the point to be calibrated. Experiments show that the optimized PSO algorithm′s optimization ability has increased by 27.23%, the convergence speed has increased by 66.67%, and the extraction error of the feature calibration point is about 0.4 pixels. After the linear structured light measurement system is calibrated, the direction along the x direction The average absolute measurement error is 0.0156 mm, and the average absolute measurement error along the z direction is 0.0174 mm.

In the actual construction process of shield machine, in order to solve the problem that when the non-contact measurement is used to detect the segment state, the segment end face has more interference, and the traditional light strip center point coordinate extraction algorithm is easy to be disturbed and fluctuated, an optimization algorithm for light strip center point coordinate extraction is proposed. Firstly, the image is preprocessed by adaptive threshold binarization and morphological processing to eliminate some interference; secondly, the weighted gray barycenter method is used to extract the coordinates of the initial light stripe center point, which is taken as the optimization object. The distance threshold and cubic spline interpolation method are used to preliminarily optimize and secondary optimize the coordinates, and the final optimized line structured light center point is obtained.The test results show that the algorithm not only improves the extraction accuracy of the center point coordinate, but also meets the industrial requirements with high real-time performance, which lays a good foundation for subsequent detection of the ellipticity of the segment and capturing the relative shield tunneling attitude of the segment.

Catalyst plays an important role in the production efficiency of products in chemical production. Some catalysts need to be calcined and heated in the process of production and manufacturing, and the traditional heating method generally uses resistance wire for heating. However, using resistance wire heating cannot reach the required temperature in a short time, and it is difficult to accurately control the temperature and heating area. Therefore, a new selective laser heating method is proposed in this paper. Firstly, the laser beam shaping is simulated by Zemax software to achieve the actual catalyst heating requirements of 200 mm2 light output area and uniform energy density (5 W/cm2) in the area. Secondly, a set of bearing device is designed to realize modular disassembly and assembly of laser, lens holding device and test tube clamping device, which is convenient for subsequent replacement and maintenance. Finally, a set of temperature detection and control scheme is proposed. Through Ansys simulation of Gaussian light source heating, it is found that the heat source power is linearly related to the maximum temperature of catalyst material receiving hot spot. The appropriate parameters of PID control laser power and temperature are obtained by using Simulink simulation PID algorithm in Matlab.

In view of the fact that there are pseudo boundary points close to the real hole boundary points in the model, the large hole recognition algorithm cannot extract the complete boundary point set and is prone to misrecognition of boundary points. A fusion of first-order tensor and second-order tensor is proposed. Hole boundary feature point detection method based on voting algorithm. First, establish a new attenuation function to achieve the preliminary extraction of the boundary points of the first-order rod tensor voting in the neighborhood; then perform the eigenvalue and saliency of the semi-definite matrix obtained by the addition of the second-order rod, board, and ball tensors correspondence analysis, further extract the boundary points of the hole; finally, the boundary point set extracted twice is combined, and the noise is removed at the same time to achieve the purpose of detecting the boundary point of the hole. Experimental results show that this method can effectively eliminate the influence of false boundary points on the extraction of hole boundary features, can achieve a more ideal detection effect, is more robust to noise, and has a low algorithm complexity.

Tunable diode laser absorption spectroscopy tomography (TDLAT) is one of the combustion diagnosis methods. Aiming at the problem that the existing TDLAT reconstruction algorithm is difficult to reconstruct gas parameters rapidly and accurately in limited-data absorption spectroscopy, the existing TDLAT reconstruction algorithm based on convolutional neural network (CNN) is improved by combining with the deep learning theory, which improve the accuracy of reconstructed flame temperature distribution to a large extent, and is suitable for different flame characteristics and a variety of beam arrangements. The CNN training and structure optimization methods for TDLAT reconstruction are studied. The necessity of preprocessing the integrated absorbance data and the temperature data is discussed. A hierarchical learning model is proposed, which effectively utilizes the prior smoothness information of gas parameters. The verification results on gaussian phantoms show that the average reconstruction error of this algorithm is only 0.24% when there is no noise. The algorithm is further validated on turbulent methane plume. Finally, a flat flame burner temperature measurement system is built. The experimental results show that this algorithm can rapidly reconstruct the two-dimensional temperature distribution at the z=1.5 cm cross section of the flame under different combustion states.

A high sensitivity NMR magnetometer is realized by laser pumping in this paper. In this scheme,87Rb-129Xe atoms are used as the working material, a resonance laser is used to polarize the reactive alkali metal atom87Rb, and then to polarize the nucleus of129Xe by means of spin exchange collision.Under the action of fixed magnetic field and driving magnetic field, the macroscopic magnetic moment of atoms precesses, and the precession frequency is proportional to the fixed magnetic field.When there is an external magnetic field in the direction of the fixed magnetic field, the precession frequency detected will change, and the magnetic field can be accurately measured by the change of precession frequency. We tested the magnetometer from the sensitivity, linear responsiveness and resolution.Result shows that the magnetic sensitivity was 0.28 pT/Hz1/2 (@1 Hz), the resolution was better than 0.171 nT, and the non-linearity was 0.662 6%.

In order to solve the problems such as crazing deformation and hole caused by missing point cloud in 3D model reconstruction of complex curved buildings, a research scheme combining 3D laser scanning technology and oblique photogrammetry technology is proposed, which is to obtain laser point cloud after the data and the oblique image point cloud data, the two point cloud data are registered and fused. This paper takes a complex surface building as an example, uses the improved SICP algorithm to complete the registration fusion of two point cloud data, and realizes the 3D model reconstruction of the complex surface building through the fusion point cloud data. The experimental results show that the registration and fusion of laser point cloud and oblique image point cloud can effectively construct high-precision and high-resolution 3D models.

The ore pass is an important part of the mining system, and its deformation degree is directly related to the safe production of the mine. Aiming at the problems of traditional detection methods such as low efficiency, poor accuracy, and intuitionistic results, the article proposes a method for detecting deformation of the main ore pass based on simultaneous localization and mapping technology. First, a handheld type based on SLAM technology is designed. The laser scanner acquires data inside the main ore pass, and uses the three-dimensional Delaunay growth method to construct a three-dimensional ore pass model to accurately extract the internal deformation information. Deformation detection of a pass in a gold mine in Shandong. Experimental results show that mobile measurement based on SLAM technology can quickly and comprehensively obtain three-dimensional data inside the pass, and the results can meet the accuracy requirements of the later treatment work of the ore pass well.

In order to observe the clinical efficacy of single-point vaporization and double-point vaporization in the treatment of patients with lumbar disc herniation by percutaneous laser disc decompression (PLDD), 82 patients with lumbar intervertebral disc herniation were enrolled, and they were divided into two groups by random number table method, 41 cases in single-point gasification group in group A, 41 cases in double-point gasification group in group B, and both groups were local under anesthesia, a percutaneous stimulation phosgenation decompression operation was performed under the guidance of the "C" arm, and connected to a manometer to measure the pressure, compare the pressure difference in the intervertebral disc, and evaluate the clinical efficacy with MacNab, VAS, and ODI scores. The results show that all patients successfully completed PLDD under local anesthesia and completed the follow-up. The pressure in the lumbar intervertebral disc of the two groups of patients changed significantly before and after the operation, which was statistically significant (P＜0.05), and the average average pressure difference before and after the operation was (5.2±1.6) mmHg, but the pressure in the lumbar intervertebral disc between group A and group B was not statistically significant (P>0.05); the preoperative and postoperative follow-up evaluation results of the two groups of patients showed that the excellent and good rate of patients in group A was 92.7%, the excellent and good rate of patients in group B was 90.2%, the total excellent and good rate was 91.5%, the total effective rate was 97.6%, and the total recurrence rate was 2.4%. There was no statistically significant difference in the excellent and good rate and effective rate between the two groups (P>0.05); The results of the low back pain VAS score and ODI score of the two groups of patients before and after treatment showed that the low back pain VAS score, leg pain VAS score and ODI score of the two groups were significantly lower than those before the operation, and the difference was statistically significant (P＜0.05). The comparison of follow-up 3 days after operation and 3 months after operation showed that the VAS score, leg pain VAS score and ODI score of the two groups of patients were also significantly reduced, and the difference was statistically significant (P＜0.05). The results of low back pain VAS score, leg pain VAS score and ODI score between group A and group B showed that the difference between the two groups was not significant, and there was no statistical significance (P>0.05). Conclusion: PLDD can significantly reduce the intradiscal pressure in patients with lumbar disc herniation and improve the clinical symptoms of patients, but the clinical efficacy is not affected by single-point vaporization and double-point vaporization.

In order to observe the exprssion of SP and ALP in rat pulp after direct pulp capping by low level laser +Dycal, 64 SD rats were randomly divided into 4 groups (n=16):Normal control group (ZC group), low level laser group (LLL group), Dycal group (Dy group) and low level laser+Dycal group (LLL+Dy group). The first molars of the left maxillary and mandibular of the rats mechanical wear pulp after direct pulp capping. SP and ALP expression in pulp tisssue was measured with immunohistochemical staining in different time. The mean optical density (MOD) of each specimen was measured. The results show that: According to the statistical analysis of two-factor univariate variance, there was a significant difference in SP expression on the 7th and 14th day after surgery. SP expression reached its peak and LLL+Dy group>Dy gruop>LLL group>ZC group(PLLL group>Dy group>ZC group (P<0.05) on the 7th day. SP and ALP expression gradually decreased to normal level with the formation of repaired dentin on the 28th day. Conclusion: The low level laser and Dycal can promote the repair of pulp injury and the formation of restorative dentin, which may be related toinduction of the expression of SP and ALP.