In order to test the compressive mechanical properties of porous Ti6A14V alloy specimens with different unit structures, porous specimen models with a pore size of 550 m, a porosity of 65%, and unit structures of 90° V-shaped, regular tetrahedron, cube, and regular octahedron were designed using laser selective melting. The appearance and structural morphology of the formed specimens were observed, and the results were similar to the designed models with a low mismatch rate. Static compression tests were conducted, and the test results showed that the compressive strengths of the 90° V-shaped, regular tetrahedron, cube, and regular octahedron structures were 51.69 MPa, 358.32 MPa, 202.54 MPa, and 279.72 MPa, respectively, with elastic moduli of 2.39 GPa, 9.67 GPa, 5.88 GPa, and 7.81 GPa, respectively. Simulations of the equivalent stress and strain in the porous structures demonstrated that the 90° V-shaped structure exhibited the highest peak stress and strain, suggesting the weakest load-bearing capacity. Conversely, the regular tetrahedron structure displayed a uniform stress distribution and the strongest load-bearing capacity. The regular tetrahedron structure had a uniform stress distribution and the strongest load-bearing capacity. The simulation results are consistent with the experimental results. Finally, the fracture morphologies of the specimens after compression testing were observed, showing a combination of a large number of tearing edges, indicating brittle fracture as the dominant failure mode.

The remelting process in selective laser melting (SLM) significantly influences the surface precision of fabricated samples. This study numerically simulates and experimentally investigates the impact of varying remelting times, powers, and scanning methods on the quality of Ti6Al4V single tracks produced by SLM. The results show that at laser powers below 250 W, increasing remelting power, the number of remelting passes, and altering the remelting direction can enhance the surface quality of the single track. Additional remelting passes reduce surface defects within the melt track. Among the tested methods, round-trip remelting scanning is most effective for improving surface quality. Changes in the weld pool width are identified as the primary factor affecting the melt track′s surface quality. Furthermore, an increase in remelting passes leads to the expansion of phase grain boundaries and an increase in phase transformation.

This research investigates the use of laser direct deposition for the repair of superalloy components, focusing on the repair of damaged GH4169 alloy parts with GH738 substrates. The laser direct deposition process was utilized to fabricate a GH4169/GH738 dissimilar material joint, and an analysis of its high-temperature mechanical properties and microstructure was conducted. The results showed that the tensile strength of laser direct deposited GH4169/GH738 joint at 650 ℃ reached 1 003 MPa, and elongation reached 16.8%; dense metallurgical bonding was formed at the joint cladding interface; the fracture mode of high temperature tensile presented ductile, and a large number of equiaxed dimples were formed on the fracture surface.

Based on the laser internal powder feeding cladding technology, the tip repair technology of ultra-thin variable width aviation turbine blades is studied. According to the blade geometric model, the trajectory planning is carried out, the variable width melt channel model is established, and the single-channel one-time scanning is realized layer by layer. A water-cooled copper plate clamping device is designed as heat dissipation protection at the blade tip. The CCD layer height control system is used to correct the height of the cladding layer in real time to the desired value. The experimental results show that the thickness of the cladding layer repaired on the blade substrate with a thickness of 0.2 mm~2 mm is between 0.67 mm and 2.49 mm, and the heights are generally the same everywhere. The metallographic microstructure is relatively uniform and dense, and there is no obvious crack defect. Variable spot cladding avoids the problems of multi-lap welding channel bulge and repeated heating, improving the cladding accuracy and efficiency. Meanwhile, it provides a reference for the repair and forming of ultra-thin and variable width parts.

In order to investigate the effect of TiC on the microstructure of 304 stainless steel fusion cladding layers, 304 fusion cladding layers without and with varying TiC contents were analyzed by optical microscopy (OM), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The results demonstrate that the solidification model of 304 stainless steel is the FA model. The 304 stainless steel microstructure is austenite and ferrite, and the cladding layer is composed of planar, columnar, and equiaxial crystals, from bottom to top. The TiC is primarily distributed in small round and square grains, with a minor amount present in the agglomerated state. The 10% TiC cladding layer comprises TiC and Cr23C6, with the grains arranged in an isometric crystal morphology. The lower and middle layer grains exhibit strong parallelism within the needle structure, while the upper layer grains display coarsening, however, the needle parallelism is not evident. The 20% and 30% TiC cladding layers have been observed to contain an -Fe martensite phase. The grains of the 20% TiC cladding layer are observed to be large islands, granular, and rod-like, with the grains undergoing grain refinement from bottom to top. The morphology of the 30% TiC cladding layer is granular and rod-like, from the bottom to the top, the grains exhibit slight coarsening. The effect of TiC on the microstructure mechanism can be described as follows: TiC addition can facilitate heterogeneous nucleation and impede grain growth, thereby promoting microstructure refinement. The TiC content in the lower layer of the fusion cladding is relatively low, the TiC of re-nucleation after dissolution and unmelted TiC, which form fine grains as nuclei. In the upper layer of the cladding, the TiC content increases, the proportion of grains reliant on the nucleation of unmelted TiC particles increases, and the formation of grains is coarser than in the lower layer. The addition of TiC powder alters the morphology of the grains in the cladding. With an increase in TiC content, the cladding layer appears to have a martensite phase, and the content and number of holes in the upper layer increase with elevation of the TiC. The study can provide insight into the organization morphology change principle of 304/TiC composite coatings.

CoFeCrNiV cladding layer was prepared on the surface of automobile welding parts by laser cladding technology. The phase composition, metallographic microstructure and crystallographic characteristics of cladding layer were analyzed respectively, and the hardness and wear resistance of cladding layer were studied. Specific conclusions are as follows: The phase composition of the CoFeCrNiV cladding layer is a single FCC solid solution phase. The lattice distortion of the FCC phase is caused by the V element dissolving in the FCC phase, which promotes the solid solution strengthening effect of the FCC phase. The average microhardness of CoFeCrNiV is 466.7±6.9 HV, 1.9 times higher than that of the 201 matrix, with solution strengthening and dislocation strengthening identified as the primary contributors to its elevated hardness. The average friction coefficient of CoFeCrNiV cladding layer is 0.55. The specific wear rate of CoFeCrNiV cladding layer is 1.91×10-5 mm3/(N·m), approximately 0.32 times that of the substrate, indicating its superior wear resistance. The predominant wear mechanisms for the CoFeCrNiV cladding layer are adhesive and abrasive wear. The study demonstrates that the hardness and wear resistance of CoFeCrNiV coating on 201 stainless steel surface of automobile welded parts can be significantly improved by laser cladding technology.

In the laser direct metal deposition forming, surface flatness is the key to its forming quality. To obtain the ideal surface flatness, ER-2209 wire was selected, and the weld seam was shaped based on a single-layer, single-pass fusion weld by laser side-axis feeding. MATLAB software was used for image processing, seam feature extraction, and mathematical fitting. The experimental results show that the parabolic model of the conventional weld differs greatly from the characteristics of the actual clad weld. In order to ensure that the error is controllable and at the same time avoid the generation of unfavorable factors, after several groups of fitting results of different orders are compared, it is found that the use of the 6th order function is a better fit for the experimental object. The optimal fitting function can be derived from the fitting results of the weld curve, and then the best theoretical lap rate can be solved by using the idea of differentiation to establish the mathematical model of optimal flatness. The surface flatness model proposed in this paper was verified by 5 sets of single-factor laser side-axis wire feeding lap experiments. The results show that the weld surface flatness is a function of weld characteristics and interlayer offset, and the theoretical optimum lap rate of the model is 30.46%, ideally between 30% and 35% for experimental verification, the theoretical optimum lap rate holds within the allowable experimental error. In the actual laser side axis feed wire fusion forming process, small flexible adjustments based on the theoretical optimal lap rate can be made according to the actual situation.

As Moore′s Law nears its physical constraints, the pursuit of innovative techniques in integrated circuit (IC) fabrication intensifies, focusing on advanced processes and packaging methodologies. As a high-precision processing method without mechanical contact, laser technology has outstanding advantages in its micro-scale precise physical control capabilities. This paper delves into the diverse applications of laser technology within IC fabrication, including its pivotal role in EUV (extreme ultraviolet) lithography for advanced processes and its utilization in TSV (through dilicon vias), bonding/debonding, laser scribing, hidden cutting, and laser annealing—all of which are essential in advanced packaging technologies. This article summarizes the development prospects and challenges faced by laser technology in IC fabrication, points out the necessity of technological innovation and process improvement, and looks forward to how laser technology will help the IC industry achieve new breakthroughs and development.

Laser machining is a processing technique that utilizes the properties of laser beams interacting with matter to cut, weld, surface treat, punch and micro-process materials. The research progress, application prospects, and development trends of various laser processing techniques were examined in typical aviation structural materials, including nickel-based alloys, aluminum alloys, titanium alloys, and high-strength steels. The impact of different processing methods on the quality of processing and forming was summarized. The characteristics of laser processing technologies such as welding, cladding, cleaning, cutting, and additive manufacturing were compared and analyzed. The significant advantages and existing problems of laser processing technology in the field of aviation structural components were summarized, and its future development and application were discussed.

This paper investigates the critical factors influencing cutting efficiency and quality in practical production applications, focusing on the use of a 355 nm wavelength laser to cut 1mm thick carbon fiber plates. Under the premise of ensuring the free drop of the cutting area, the single factor control variable method was used to explore the effects of duty cycle, slit width and spot overlap rate on cutting quality and cutting efficiency. The results show that the extreme parameter values negatively affect cutting efficiency, with the duty cycle ratio exerting the most significant impact. The thermal impact on the cutting edge is similar to the trend of the amount of edge collapse, while the greatest impact on the cross-sectional taper is the change in seam width. Under the condition that the thermal impact is less than 225 m, edge collapse is less than 85 m, and the taper is less than 0.1, the minimum time required to make it fall automatically is 26.44 s.

Carbon fiber reinforced plastics (CFRP) is widely used in the field of aerospace and new energy vehicles. Traditional machining methods are usually used to process CFRP, but the cost is high and the efficiency is low. Laser processing method has the advantages of high efficiency, green and high precision, but there is a large heat affected zone in laser processing CFRP. In order to explore the transfer rule of laser energy in CFRP and restrain the generation of heat affected zone, the experiments for CRFP of CO2 continuous laser spot and rectangular cutting were carried out. The spot experiment showed that the maximum power density of the laser was determined to be 198.84 W/mm2. The single rectangular cutting experiment showed that the energy was mainly transferred to the carbon fiber on the surface of the material and affected the thermal expansion and melting of the resin. When the scanning speed was 3 mm/s and the laser power density was 198.84 W/mm2, the concave convex fluctuation value (Fv) of the rectangular surface reached the maximum of approximately 25.83 m, and the surface energy accumulation was most obvious. In addition, it was found that the increasing scanning speed or the decreasing laser power could effectively reduce the concave convex fluctuation value and suppress the expansion of the heat affected zone. The multiple rectangular cutting experiment showed that under the condition of different processing times, the phenomena of the laser energy transfer layer at surface level and between layers were existed. When the number of processing times was 15, the concave convex fluctuation value reached the maximum of approximately 41.75 m. When the number of processing times was 20, the energy transfer between layers was better than that at surface level.

This study investigates the surface morphology characteristics of TC4 titanium alloy material subjected to water jet-guided laser processing. Cutting tests were performed on 2 mm thick TC4 titanium alloy rolled plates using LCS305 water jet-guided laser processing equipment from Synova. The surface morphology of the cuts was examined using a CCD industrial microscope, scanning electron microscope, and optical profilometer. The experimental results show that the cross-section of TC4 titanium alloy processed by water jet-guided laser will produce transverse stripes, and the number of transverse stripes is the same as the scanning cycle of water jet-guided laser. The cutting surface of TC4 titanium alloy can be divided into four kinds of regions according to the different characteristics, namely: uplift zone, depression zone, crushed stone zone and ripple zone. The morphology and generation mechanism of each region are preliminarily analyzed.

In this paper, the processing of micro hole on thick alumina ceramic by using a QCW high-power fiber laser was studied. The influence of laser process factors such as peak laser power, pulse width, pulse frequency, and defocusing amount on micro-hole shape and quality was primarily explored. The experimental results show that micro-holes with high roundness, minimal taper, reduced slagging, and no cracks can be achieved on thick alumina ceramic plates at a peak laser power of 5.0 to 6.5 kW, a pulse width of 4 to 8 ms, a frequency of 50 to 100 Hz, and a defocusing amount of -3 to -4 mm. The radius of the micro-hole can be controlled in the range of 130~400 m, and the taper of the hole can be varied in the range of -1.4°~-0.6°. By modelling the temperature field of the drilling process, it is discovered that the accumulation of heat near the exit of the micro-hole is the primary cause of the machined hole shape′s inverted taper.

In this paper, in order to meet the needs of transparent glass decoration and high-quality graphic marking, UV nanosecond laser source is used to conduct laser direct identification technology research on the surface of transparent glass materials (high borosilicate glass, quartz glass). By changing the laser process parameters, the effects of the cumulative pulse energy density, peak power density and laser pulse scanning mode on the integrity, roughness and ablation depth of the marking area were studied, so as to understand the marking characteristics of two kinds of glass materials. The experiment results show that the cumulative pulse energy density mainly affects the integrity of the logo pattern. The peak power density determines the damage threshold of the material identification, and the filling mode with the short side scanning back and forward is more complete. Compared with high borosilicate material, quartz material has higher damage threshold and wider processing window.

In recent years, stainless steel surface laser-induced coloring process has become one of the key research hotspots of laser technology due to its simple process, high processing accuracy, easy automation, environmental protection and other advantages. Despite these advantages, challenges such as low color saturation and inadequate color reproducibility persist. This study undertakes a full-factor experiment to delineate the formation of five primary colors on 304 stainless steel surfaces using a laser marking machine. The study correlates the micro-morphology of the experimental samples to validate the coloring mechanism and scrutinizes the causes of color unevenness. Utilizing the outcomes from the full-factor test, an orthogonal test is designed for each color system. Subsequently, SPSS software is employed to conduct a multi-factor analysis of variance (ANOVA), elucidating the impact of process parameters—encompassing laser power, frequency, scanning distance, and speed—on the three-channel values within the HSV color space. The findings provide valuable insights into the regularity and significance of process parameters, offering a practical reference for optimizing laser-induced coloring processes.

A novel full optical path laser methane sensor probe has been developed for continuous, safe, and accurate in-situ monitoring of mine gas (methane) concentration. The methane probe, with a volume of only 4 cm×8 cm (cylindrical), is housed in a stainless steel casing to ensure measurement safety. Internally, the probe consists of all optical components without any related electrical structures, utilizing a three-mirror reflection system to form the optical path. The absorption path of the probe is approximately 20 cm. The methane probe is characterized by its high sensitivity, strong robustness, and high safety. To validate its performance, a methane concentration detection system based on laser probes was constructed in the laboratory, using a distributed feedback laser (DFB) with a central wavelength of 1 653.7 nm as the light source. The system combined wavelength modulation spectroscopy (WMS) and direct absorption spectroscopy (DAS) technologies to achieve high-sensitivity detection of methane gas. Experimental results demonstrate that, at room temperature and pressure, the measurement error is less than ±5.0×10-4 for low concentrations (0~1%), and less than ±5% of the true value for high concentrations, with a full-range linear fitting coefficient of 0.999 8. The detection limit of the sensor (1 standard) is 68 ppm and the response time is not exceeding 10 s. Experiments confirmed that different distances (1 km、2 km、5 km) from the probe have almost no effect on methane concentration measurements. These results confirm the probe′s capability for accurate methane detection and its suitability for in-situ mine gas monitoring.

In the domain of precision measurement and sensing technology, laser feedback technology is widely used due to its unique advantages. In order to reduce the impact of deadpath error on the system, a measurement method based on laser feedback effect was proposed, and the full quasi-common-path measurement system was constructed. The working principle and optical structure of the system were analyzed, and the resolution and stability of the system were experimented. The experimental results show that the full quasi-common-path method can improve the system resolution to 2 nm, and it has good stability at different distances and times. It effectively diminishes the influence of environmental fluctuations and significantly compensates for deadpath errors, making it suitable for displacement and vibration measurements in precision machining equipment.

The traditional detection methods of substance concentration are mainly based on absorption spectrophotometry, including spectrophotometer, gas phase or liquid chromatography, etc. Although these methods have high sensitivity, due to the complex testing process, testing equipment is too large and time-consuming. Therefore, a convenient method for measuring small changes in refractive index of solution is investigated. We mainly use the high order model of the double-sided metal clad waveguide to achieve the high sensitivity of measurement. We proposed a bimetallic clad waveguide structure, the sample to be tested was used as its guide layer, and two metal films were used as its cladding layer. A tiny change of extinction coeffient in the waveguide guiding layer where the acetic acid solution and bromocresol green can lead to a significant change of light intensity in the reflection spectrum. Trace detection of substances was achieved by using the Attenuated Total Reflection curves of the double-sided metal-clad waveguides in response to the waveguides structure. Both theoretical simulation and experimental results showed that using this method, the detection limit of acetic acid can be as low as 1.3 nm, which was 16 times higher than the surface plasma field enhanced resonance scattering (SP-RLS) method, and four times higher than flame atomic absorption spectrometry and fluorescence spectrometry, respectively. This method is a real-time detection technology of solution concentration which is short in time, requires less samples, has high stability, is convenient and cheap, and provides an effective detection route for the chemical production process in the future.

With the increase of the service life of the curtain wall of existing buildings and the impact of the harsh environment, China, as the world's first curtain wall producer and user country, is frequently harmed by accidents such as curtain wall falling off. This study first reviews the key failure types and influencing factors of curtain walls of existing buildings, and analyzes the safety status of existing curtain walls and the risk of accidents such as curtain wall falling off. Subsequently, this study summarizes traditional curtain wall safety detection methods such as visual method and pulling method, and finds that the existing technical means have the characteristics of low accuracy, poor timeliness or high cost, and it is difficult to cope with the rapidly increasing demand for curtain wall safety status evaluation. It is concluded that a new type of detection method is urgently needed in the field of curtain wall safety detection to change this situation. Finally, based on the application of laser vibration measurement in curtain wall inspection, it is concluded that the non-contact laser vibration detection method formed by the relationship between the dynamic characteristic attributes of the existing building curtain wall and its safety has more application prospects in terms of accuracy, timeliness and cost than the existing technical means. Non-contact non-destructive testing methods are the development direction of curtain wall safety testing in the future. Based on the rapid development of sensing technology, this study provides guidance and direction for the future realization of comprehensive and refined supervision of building curtain walls.

Because the high-precision detection of large-aperture plane mirror surface shape is a process of precise adjustment, the surface shape recovery accuracy is easily disturbed by human subjective factors in the detection process. In order to solve the problem of high-precision surface shape detection of large-aperture plane mirrors, the eccentricity error of optical path detection and the resulting change in the calculation accuracy of the ritchey angle, the distance from the center of the interferometer to the plane mirror and other linkage errors are analyzed. By using optical software to build a 2 m plane mirror detection model, set different eccentricity errors to obtain the system wave aberration, solve the system wave aberration data to obtain the plane mirror shape data to be measured, and compare it with the preset standard surface shape. The analysis shows that the surface shape recovery result is more sensitive to the eccentricity error. It is necessary to ensure that the difference between the two ritchey angles is within the range of 12°~25°, and the eccentricity error is controlled within 5% of the diameter during detection. It is not sensitive to the eccentricity error and the change of linkage error caused by it, and the RMS accuracy of the surface to be measured is within 10-3. Based on the above error simulation analysis, the actual 2 m plane mirror surface shape detection is guided, and the results show that the RMS of the plane mirror reaches 0.020 9 , and the PV is 0.128 4 (=632.8 nm). The purpose of this paper is to reveal the degree of influence of eccentricity error and linkage error on the shape of a 2 m plane mirror, which has a guiding role in the construction of the actual optical path of the large-aperture mirror plane mirror and the reduction of artificial adjustment errors.

The traditional iterative closest point registration method relies on the initial pose of the registration point cloud, otherwise it will fall into the local optimal solution during iteration, resulting in low registration accuracy. Aiming at the shortcomings of the traditional iterative closest point registration method, this paper proposes a point cloud registration method based on the eigenvalue deviation ratio, so that the point cloud can have a better initial pose when iterative closest point registration. The point cloud registration method proposed in this paper firstly performs voxel filtering preprocessing on the decentralized initial point cloud. Secondly, the method uses the deviation ratio of the eigenvalue to screen out the feature points. Thirdly it uses the invariant characteristics of the neighbor dimension of the point cloud to find the matching points of the two groups of point clouds, and then performs coarse registration. Finally the method uses the improved iterative closest point for fine registration. Experimental results show that the point cloud registration method proposed in this paper can make the registration point cloud have a good initial pose, compared with iterative closest point registration methods and registration methods based on sampling consistency initial registration and normal distribution transformation fusion. The proposed method in this paper has greater efficiency and precision.

This paper addresses the limitations of traditional point cloud registration methods, including low computational efficiency, sparse feature point extraction, and weak robustness, by introducing a novel fast point feature histogram (FPFH) closest distance ratio point cloud registration method. First, the original point cloud data is downsampled by voxels, and the feature descriptors are obtained from the downsampled data using the FPFH method. Then, the normal vector threshold of the bidirectional K dimension tree and the nearest neighbor distance ratio method are used to extract features, change the distance weight, count more point pair parameters, eliminate mismatched point pairs, speed up the point pair search, and make the registration more accurate. Huber loss function weight is introduced to optimize the objective function of rigid body registration model to enhance robustness; Then the sample consensus based method (SAC-IA) is used for initial coarse registration, and the iterative closest point (ICP) point to surface method is used to complete fine registration; In order to avoid the local minimum, Levenberg-Marquardt (LM) algorithm and singular value decomposition (SVD) alternate iteration strategy are used for optimization. Compared with ICP, SAC-IA+ICP, Intrinsic Shape Signatures (ISS)+ICP and FPFH+ICP, the experiment shows that the registration speed of the proposed method is 31.07%, 53.46%, 3.09% and 25.05% higher than that of the ISS, 49.09% higher than that of the ISS, and an order of magnitude higher than that of ICP and SAC-IA+ICP. When the number of iterations is small and the precision setting is large, the registration precision is the same as that of the FPFH+ICP method, but the speed is faster than that of the FPFH method. In the case of noise, the speed of this algorithm is 30.53% higher and the registration accuracy is 15.47% higher than that of FPFH, which is smoother; Compared with ISS registration algorithm, the registration accuracy is improved by an order of magnitude, and the average registration time is slightly faster; ICP and SAC-IA+ICP methods failed to register and did not participate in the comparison. The experimental results show that this method is feasible, the registration speed and accuracy are improved, and the robustness and stability are better.

Mode mismatch is a primary factor contributing to coupling loss in heterogeneous optoelectronic devices. In this paper, the transmission characteristics of the semiconductor laser and the photonic crystal fiber are researched. Besides, optical lens are designed to achieve the shaping and modification of the output light of the semiconductor laser. In addition, the coupling efficiency, alignment accuracy requirements and 3 dB mismatch tolerance of the semiconductor laser and photonic crystal fiber coupling system are analyzed by using mode overlap integration. The research results show that the semiconductor laser can be highly matched with the photonic crystal fiber mode after optical lens shaping and modification, and coupling efficiency and 3 dB alignment tolerance can achieve 91% and 0.5 m, respectively.

In this paper, an interferometric integrated optical gyro system based on silica waveguide interference ring is proposed and designed to realize the miniaturization and integration of interferometric integrated optical gyro. Firstly, the structure and cross section size of silica waveguide were determined, and the cross-section size was 4.5 m×4.5 m. Secondly, the bending radius of silica waveguide rings is determined to be 10 mm and the spacing between waveguide rings is determined to be 50 m. Finally, the length of 2.434 m silica waveguide interference ring is fabricated. Meanwhile, an interferometric integrated optical gyroscope tst system was built using the silica waveguide ring, and the Allan variance of gyroscope was 110.5 (°)/h. The successful fabrication and testing of the waveguide ring is beneficial to reduce the volume of interferometric gyroscope and promote the engineering application of interferometric integrated optical gyro.