Browse Topic: Lasers

Items (2,227)
The accelerating global shift towards decarbonised energy systems has positioned hydrogen as a highly promising carbon-free fuel. This study comprehensively investigates the macroscopic characteristics and temporal evolution of vortex ring trailing helium jets, serving as a surrogate for hydrogen, injected into a quiescent ambient environment using high-speed Schlieren imaging. This research addresses critical insights into fuel-air mixing dynamics essential for optimising hydrogen direct injection (DI) internal combustion engines. Analysis of helium jet tip’s topology revealed a three-stage evolution from an initial pressure-insensitive phase, dominated by pressure wave structures, to a momentum-driven, vortex-dependent growth stage, then to a fully developed stage. Specifically, the lower-pressure cases showed increased Kelvin-Helmholtz instability and distinct head vortex pinch-off at the final stage. Jet tip velocities transitioned from initial high, rapid pressure wave development
Dong, ShuoShi, HaoZhang, GengxinFeng, YizhuoLu, EnshenWang, XinyanZhao, Hua
The present study examines the influence of process parameters on the effect of strength and crystalline properties of AlSi10Mg alloy with laser sintered process. A detailed work was carried out with the effects of varying the laser power, scan speed, and hatch distance on crystalline structure, hardness, and surface roughness. From the analysis, the improved surface quality and mechanical performance were achieved with a scan speed of 1200 mm/s, a laser power of 370 W, and a hatch distance of 0.1 mm. An increase in hardness, improved surface finish, and reduced porosity was observed with decreased hatch distance. However, the balanced results were obtained for scanning speed of 1200 mm/s and laser power of 370 W. The ideal processing conditions decreased the crystalline size, increasing the overall material strength, when crystalline analysis was carried out. The higher scanning speeds supported improved grain refinement and heat diffusion, with the poor hardness value. With the lower
Shailesh Rao, A.
Trains traditionally transmit braking and mitigation commands through the air tube filling and exhausting method, which is easy to cause local large longitudinal impact. In order to meet the high-precision requirements of synchronous transmission of commands for heavy-duty trains with large groupings, this paper proposes a laser+industrial Ethernet network control system, which can meet the requirements of flexible train grouping and virtual connecting under the premise of ensuring synchronous transmission of commands for trains with large groupings. The system consists of central control unit, locomotive laser communication module, locomotive switch, mobile wireless communication terminal, security gateway, vehicle control unit, vehicle laser communication module, vehicle switch, etc. It is designed according to the three-layer architecture of vehicle-level network, train-level network and line-level network, which can realise the issuance of internal control commands and status
Meng, XiangzhenLi, ChuanhuZhu, Youlong
Air pollution is a significant long-term public health issue, with on-road traffic emissions being a primary contributor, especially in urban areas. Remote emission sensing (RES) is an innovative method for large-scale monitoring of vehicle emissions. It not only enables accurate detection of pollutants from vehicles under real-world driving conditions but also offers actionable insights to optimize engine performance. The point sampling-based RES technique involves sampling the vehicle exhaust plume along the roadside with a sampling line and using exhaust analyzers. In this method, the sampling line is placed alongside the road for sample extraction. Thus, the sampling position and knowledge regarding the spread of the exhaust plumes are crucial. Other modern RES systems utilize laser absorption spectroscopy to measure the pollutants in vehicle exhaust. For accurate absorption measurements, the laser’s height must align with the height of the exhaust plume, and the absorption length
Imtiaz, Hafiz HashimLiu, YingjieSchaffer, PaulKupper, MartinBergmann, Alexander
This article presents a novel mechanical model for simulating the behavior of pavement deflection measuring systems (PDMS). The accuracy of the model was validated by comparing the acceleration of the new model with the data achieved through experimental tests fusing a deflection measurement system mounted on a Ford F-150 truck. The experimental test for the PDMS is carried out on a random road profile, generated by an inertial profiler, over a 7.4-mile (12 km) loop around a lake near Austin, Texas. Integrating a reliability-based optimization (RBO) algorithm in a PDMS aims to optimize system parameters and reduce vibrations effectively. The PDMS noises and uncertainties make it crucial to use a robust system to ensure the stability of the system. This article presents a robust algorithm for considering the uncertainties of PDMS parameters, including the damping coefficients and spring stiffness of the supporting brackets. Moreover, it considers the variation of system parameters, such
Yarmohammadisatri, SadeghSandu, CorinaClaudel, Christian
Artificial intelligence systems like ChatGPT are notorious for being power-hungry. To tackle this challenge, a team from the Centre for Optics, Photonics and Lasers (COPL) has come up with an optical chip that can transfer massive amounts of data at ultra-high speed. As thin as a strand of hair, this technology offers unrivaled energy efficiency.
Researchers in the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and Vienna University of Technology (TU Wien) have invented a new type of tunable semiconductor laser that combines the best attributes of today’s most advanced laser products, demonstrating smooth, reliable, wide-range wavelength tuning in a simple, chip-sized design.
Researchers have developed a 3D microprinted sensor for highly sensitive on-chip biosensing. The sensor, which is based on a polymer whispering-gallerymode microlaser, opens new opportunities for developing high-performance, cost-effective lab-on-a-chip devices for early disease diagnosis.
Medical tubing is an essential component of countless healthcare applications, from intravenous (IV) and oxygen lines to catheters and diagnostic equipment. These tubes, often made of clear flexible polymers, must be produced to exacting standards: free of contaminants, strong under pressure, and biocompatible. However, the joining process to connect these tubes can introduce significant manufacturing challenges.
Metabolic imaging is a noninvasive method that enables clinicians and scientists to study living cells using laser light, which can help them assess disease progression and treatment responses. But light scatters when it shines into biological tissue, limiting how deeply it can penetrate and hampering the resolution of captured images.
Despite all the technological evolution in navigation, waters just off coastal shores around the globe have remained a black box. That is, until researchers from The University of Texas at Austin and Oregon State University developed a new technology that uses satellites in space to map out these tricky areas.
Researchers have demonstrated a new technique that uses lasers to create ceramics that can withstand ultra-high temperatures, with applications ranging from nuclear power technologies to spacecraft and jet exhaust systems. North Carolina State University, Raleigh, NC A new technique that leverages the concept of sintering, can be used to create ceramic coatings, tiles or complex three-dimensional structures, which allows for increased versatility when engineering new devices and technologies. “Sintering is the process by which raw materials - either powders or liquids - are converted into a ceramic material,” says Cheryl Xu, co-corresponding author of a paper on this research and a Professor of Mechanical and Aerospace Engineering at North Carolina State University (NCSU). “For this work, we focused on an ultrahigh temperature ceramic called hafnium carbide (HfC). Traditionally, sintering HfC requires placing the raw materials in a furnace that can reach temperatures of at least 2,200
A new technique that leverages the concept of sintering, can be used to create ceramic coatings, tiles or complex three-dimensional structures, which allows for increased versatility when engineering new devices and technologies.
This document applies to safety observers or spotters involved with the use of outdoor laser systems. It may be used in conjunction with AS4970.
G-10T Laser Safety Hazards Committee
A pacemaker is a small device that helps control your heartbeat so you can return to your normal life. It has three main parts: a pulse generator that creates electrical signals, a controller-monitor that manages these signals, and leads that deliver the signals to the heart. One key benefit of the pacemaker is its strong titanium casing. Titanium is very strong and lightweight, and it is biocompatible, meaning it works well with the body without causing harmful reactions. This metal is highly resistant to corrosion, which helps keep the casing intact and protective even when exposed to bodily fluids.
The Department of Defense (DoD) is developing technology for satellites to communicate via lasers. Laser communications could transmit data faster and more securely than traditional radio frequency communications. DoD has made progress in developing this technology, but it has also faced delays and other issues-and hasn't fully demonstrated that it works in space. Despite these challenges, DoD plans to continue to develop and launch hundreds of satellites worth billions of dollars that require the use of laser communications.
Researchers have developed a new type of sensor platform using a gold nanoparticle array. The sensor is made up of a series of gold disk-shaped nanoparticles on a glass slide. When an infrared laser is pointed at a precise arrangement of the particles, they start to emit unusual amounts of ultraviolet (UV) light.
BlueHalo Albuquerque, NM Ashley.Young@bluehalo.com
This standard is applicable to the marking of aerospace vehicle electrical wires and cables using ultraviolet (UV) lasers. This standard specifies the process requirements for the implementation of UV laser marking of aerospace electrical wire and cable and fiber-optic cable to achieve an acceptable quality mark using equipment designed for UV laser marking of identification codes on aerospace wire and cable. Wiring specified as UV laser markable subject to AS4373 and which has been marked in accordance with this standard will conform to the requirements of AS50881.
AE-8A Elec Wiring and Fiber Optic Interconnect Sys Install
Metabolic imaging is a noninvasive method that enables clinicians and scientists to study living cells using laser light, which can help them assess disease progression and treatment responses. But light scatters when it shines into biological tissue, limiting how deeply it can penetrate and hampering the resolution of captured images.
In February, the Joint Interagency Field Experimentation (JIFX) team at the Naval Postgraduate School (NPS) executed another highly collaborative week of rapid prototyping and defense demonstrations with dozens of emerging technology companies. Conducted alongside NPS’ operationally experienced warfighter-students, the event is a win-win providing insight to accelerate potential dual-use applications.
Scientists from Tomsk Polytechnic University and Saratov State University teamed up with colleagues from Taiwan and proposed to make a laser “blade” for a medical scalpel with a specified curved shape using a photonic “hook.” Currently there are laser scalpels only with an axisymmetric focus area, i.e., with a cylindrical blade. According to scientists, changing the shape of the blade will expand the possibilities of using the laser in medicine, while it is about two times thinner than the cylindrical option. The concept and its rationale are published in the Journal of Biophotonics.
The efficiency and performance of lithium-ion batteries are highly influenced by the quality of laser cutting of electrode materials. The laser cut quality of thin foils is often measured by amount of kerf width and heat-affected zone (HAZ). This article adopts a novel approach that involves pre-cooling of thin copper foils prior to the laser cutting process. The impact of laser conditions and foil temperature were analyzed on HAZ and kerf width induced during laser cutting experiments conducted based on L27 orthogonal array. Teaching–learning–based optimization (TLBO) technique was employed to identify the optimal laser parameters. ANOVA results indicated that the temperature was the most significant factor influencing kerf width and HAZ. The optimized laser parameters identified through TLBO technique were 16 W laser power, 69.47 mm/s scanning speed, and 20 kHz pulse frequency at dry ice conditions. A reduction of 50.76% kerf width and a decrease in 7.6% HAZ were observed when the
Rao, Akshay P.Bharatish, A.Solaiachari, SivakumarKumar, S. Mahendra
Most 3D object detection methods employ LiDAR sensors to create 3D point clouds of their environment. Simply put, LiDAR sensors use laser beams to rapidly scan and measure the distances of objects and surfaces around the source. However, using LiDAR data alone can lead to errors due to the high sensitivity of LiDAR to noise, especially in adverse weather conditions like during rainfall.
Hydro-pneumatic suspension is widely used due to its favorable nonlinear stiffness and damping characteristics. However, with the presence of parameter uncertainties and high nonlinearities in the hydro-pneumatic suspension system, the effectiveness of the controller is often suboptimal in practical applications. To mitigate the influence of these issues on the control performance, an adaptive sliding mode control method with an expanded state observer (ESO) is proposed. Firstly, a nonlinear mathematical model of hydro-pneumatic suspension, considering seal friction, is established based on the hydraulic principle and the knowledge of fluid mechanics. Secondly, the ESO is designed to estimate the total disturbance caused by the nonlinearities and uncertainties, and it is incorporated into the sliding mode control law, allowing the control law to adapt to the operating state of the suspension system in real time, which solves the effect of uncertainties and nonlinearities on the system
Niu, ChangshengLiu, XiaoangJia, XingGong, BoXu, Bo
The accident reconstruction community frequently uses Terrestrial LiDAR (TLS) to capture accurate 3D images of vehicle accident sites. This paper compares the accuracy, workflow, benefits, and challenges of Unmanned Aerial Vehicle (UAV) LiDAR, or Airborne Laser Scanning (ALS), to TLS. Two roadways with features relevant to accident reconstruction were selected for testing. ALS missions were conducted at an altitude of 175 feet and a velocity of 4 miles per hour at both sites, followed by 3D scanning using TLS. Survey control points were established to minimize error during cloud-to- cloud TLS registration and to ensure accurate alignment of ALS and TLS point clouds. After data capture, the ALS point cloud was analyzed against the TLS point cloud. Approximately 80% of ALS points were within 1.8 inches of the nearest TLS point, with 64.8% at the rural site and 59.7% at the suburban site within 1.2 inches. These findings indicate that UAV-based LiDAR can achieve comparable accuracy to TLS
Foltz, StevenTerpstra, TobyClarson, Julia
The tensile and low-cycle fatigue (LCF) properties of Ti6Al4V specimens, manufactured using the selective laser melting (SLM) additive manufacturing (AM) process and subsequently heat-treated in argon, were investigated at elevated temperatures. Specifically, fully reversed strain-controlled tests were performed at 400°C to determine the strain-life response of the material over a range of strain amplitudes of industrial interest. Fatigue test results from this work are compared to those found in the literature for both AM and wrought Ti6Al4V. The LCF response of the material tested here is in-family with the AM data found in the literature. Scanning electron microscopy performed on the fracture surfaces indicate a marked increase in secondary cracking (crack branching) as a function of increased plastic deformation and demonstrating equivalent performance when compared to the wrought Ti6AL4V at RT (room temperature) at 1.4% strain amplitude and better performance when compared to the
Gadwal, Narendra KumarBarkey, Mark E.Hagan, ZachAmaro, RobertMcDuffie, Jason G.
This study investigates the nonlinear correlation between laser welding parameters and weld quality, employing machine learning techniques to enhance the predictive accuracy of tensile lap shear strength (TLS) in automotive QP1180 high-strength steel joints. By incorporating three algorithms: random forest (RF), backpropagation neural network (BPNN), and K-nearest neighbors regression (KNN), with Bayesian optimization (BO), an efficient predictive model has been developed. The results demonstrated that the RF model optimized by the BO algorithm performed best in predicting the strength of high-strength steel plate-welded joints, with an R2 of 0.961. Furthermore, the trained RF model was applied to identify the parameter combination for the maximum TLS value within the selected parameter range through grid search, and its effectiveness was experimentally verified. The model predictions were accurate, with errors controlled within 6.73%. The TLS obtained from the reverse-selected process
Han, JinbangJi, YuxiangLiu, YongLiu, ZhaoWang, XianhuiHan, WeijianWu, Kun
Researchers from the School of Engineering of the Hong Kong University of Science and Technology (HKUST) have successfully developed what they believe is the world’s smallest multifunctional biomedical robots. Capable of imaging, high-precision motion, and multifunctional operations like sampling, drug delivery, and laser ablation, the robot offers competitive imaging performance and a tenfold improvement in obstacle detection, paving the way for robotic applications in narrow and challenging channels of the human body, such as the lung’s end bronchi and the oviducts.
Monitoring the safety and structural condition of tunnels is crucial for maintaining critical infrastructure. Traditional inspection methods are inefficient, labor-intensive, and pose safety risks. With its non-contact, high-precision, and high-efficiency features, mobile laser scanning technology has emerged as a vital tool for tunnel monitoring. This paper presents a mobile laser scanning system for tunnel measurement and examines techniques for calculating geometric parameters and processing high-resolution imaging data. Empirical evidence demonstrates that mobile laser scanning offers a reliable solution for evaluating and maintaining tunnel safety.
Lianbi, YaoZhang, KaikunDuan, WeiSun, Haili
Despite its success, integrated photonics has been missing a key component to achieve complete miniaturization: high-performance chip-scale lasers. While some progress has been made on near-infrared lasers, the visible-light lasers that currently feed photonic chips are still benchtop and expensive. Since visible light is essential for a wide range of applications including quantum optics, displays, and bioimaging, there is a need for tunable and narrow-linewidth chip-scale lasers emitting light of different colors.
Metal bipolar plates are important components of fuel cells, playing a role in conducting electricity, gas, and heat during the operation of fuel cells. The sealing and joint quality of the bipolar plates have a significant impact on the performance and service life of fuel cell stacks. In actual production, laser technology is often used for welding bipolar plates, and the welding quality is ensured by laser process parameters when using the same equipment. Therefore, in order to further optimize the laser welding process of metal bipolar plates, this paper selects three laser parameters for single-factor analysis to evaluate the impact of each parameter on laser welding quality. The Box-Behnken design-response surface method is used for multi-factor analysis, with process parameters as inputs and weld quality parameters as outputs, to assess the sensitivity of each laser process parameter to laser welding quality, and to fit a nonlinear function. Based on the results, the optimal
Li, WeiChang, GuofengXu, HuashengHuang, Ziheng
Researchers from the State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, have successfully developed a wide-bandwidth, low-polarization semiconductor optical amplifier (SOA) based on tensile-strained quantum wells. The study, published in the journal Sensors, presents a significant advancement in optical communication technology, addressing the growing demand for higher bandwidth and lower polarization sensitivity.
This specification covers an alpha-beta Ti-6Al-4V alloy produced by laser powder bed fusion (L-PBF) additive manufacturing and subjected to hot isostatic press (HIP) operation. Typically, this material is used for complex-shaped aerospace products made to near net shape dimensions. These products have been used typically for parts requiring operating strength up to 750 °F (399 °C), but usage is not limited to such applications.
AMS AM Additive Manufacturing Metals
A new feature of the modern high-powered laser is the need to transmit various wavelengths through fiber optics. Fiber optics have emerged as the primary method for transmitting laser light due to its ease of setup and disconnection. Moreover, it safeguards end users from light exposure or eye contact, as the light is conveyed through an enclosed conduit.
Researchers have designed a six-hole micro-structure antiresonant air-core fiber (AR-HCF) with a large core diameter of 78 μm. The researchers say it is the first time that 2.79 μm high energy pulsed laser has been transmitted with good efficiency at room temperature.
The dissimilar welding of titanium to steel enables the integration of the advantageous properties of both metals, facilitating the design of lightweight, corrosion-resistant, and high-strength multifunctional composite structures. However, significant differences in their thermophysical properties pose substantial technical challenges in practical welding scenarios, necessitating careful selection of process parameters to enhance the quality and performance of the weld joint. This article establishes a support vector machine (SVM) model with laser power, welding speed, and laser spot diameter as independent variables, and the maximum residual stress and minimum yield strength of the weld joint as dependent variables. To improve prediction accuracy, the SVM model is optimized using the beluga whale optimization (BWO) algorithm. Taking the established model as the objective function, the multi-objective salp swarm algorithm (MSSA) is employed to optimize the laser welding process
Zhu, YubinMeng, XiangliZhang, Xinran
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