Effect Of Laser Parameters Research Articles

Review of high-precision femtosecond laser materials processing for fabricating microstructures: Effects of laser parameters on processing quality, ablation efficiency, and microhole shape

Femtosecond lasers are promising tools for achieving high-precision processing of thin materials without causing any thermal surface damage and bulk distortion. However, thermal damage can occur even with ultrashort laser pulses. This is because of high electron penetration depth and heat accumulation at high fluence and high repetition rate. Nanoparticle redeposition can be dramatically altered with variation in repetition rate. The symmetry of microholes and ablation efficiency vary with laser polarization. The laser wavelength affects the ablation efficiency and surface roughness. Therefore, understanding these laser–matter interactions that depend on the laser parameters is essential for high-precision laser processing. This article reviews laser–matter interactions in the 64FeNi alloy, as well as analytical models for designing the desired hole size and taper angles. This can help establish strategies for creating various high-precision microstructures using femtosecond lasers.

Limitations and characteristics of converted industrial acrylic sheet into an in vitro platform using CO2 laser

The recent US FDA Modernization Act 2.0 has intensified interest in microfluidic-based in vitro systems for preclinical research. However, the high costs of conventional microfabrication methods and commercial devices present significant barriers, particularly in developing countries. This study addresses these challenges by exploring the use of industrial-grade acrylic sheets and a conventional CO2 laser for cost-effective microfabrication. The research investigates the effects of laser parameters—specifically nozzle speed and power—on the dimensions and quality of microchannels, surface roughness, and bonding strength. Results indicate that increased nozzle speed reduces kerf width and enhances microchannel quality, whereas high laser power (∼52 watts) induces bubbling at the edges. A simple acetone and ethanol mixture was found to provide optimal bonding strength without altering the acrylic’s molecular structure. UV spectrophotometry revealed minimal changes (∼6 %) in visible light transmittance due to bonding conditions, while FTIR analysis showed no residuals that could potentially cause cytotoxicity. Despite variations in surface roughness resulting from the etching process, cell viability remained unaffected. The surfaces supported effective cell culture for lung (A549), neuron (SH-SY5Y), and liver (HepG2) cell lines. This approach presents a practical and cost-effective solution for developing in vitro platforms, making it an accessible option for research and academic applications.

Effect of laser parameters and shielding gas flow on co-axial photodiode-based melt pool monitoring signals in laser powder bed fusion

Melt pool monitoring using co-axial photodiodes is increasingly used for online quality monitoring in PBF-LB AM. However, the fundamental correlations between different processing conditions and the co-axial photodiode signals are not well understood. In this study the impact of laser parameters and the shielding gas flow speed on co-axial photodiode-based melt pool monitoring signals is established. It is shown that laser power has positive linear correlation with the photodiode signal, while the correlation with scanning speed is non-linear in the form of y=ax–b. The focal point position, scanning orientation and shielding gas flow speed have highly non-linear response on the photodiode signal, depending on the combinatorial effects of the parameters. These underlying physical correlations should be carefully assessed and taken into consideration when trying to establish correlations between photodiode-based melt pool monitoring signal and defect formation in the PBF-LB process.

Effect of laser parameters on microstructure and mechanical properties of Al–Ni–Sc–Zr alloys fabricated by laser powder bed fusion

The processability, microstructure and mechanical properties of a near eutectic AlNiScZr alloy fabricated by laser powder bed fusion (LPBF) are investigated. The optimal processing windows for the LPBF alloy are determined. The results indicate that laser power exerts a predominant influence on the relative density of the as-built alloy. Elevated laser power can lead to increased relative density. Laser scanning speed exerts a significant impact on the microstructure and mechanical properties of the as-built alloys. An increase in the laser scanning speed can facilitate the growth of coarse columnar grains in the coarse grain region and suppress the formation of ultrafine equiaxed grain bands. Furthermore, the increase in the laser scanning speed can result in a reduction in the size of the cells, which in turn leads to an enhancement in the strength of the alloys. This study examines the evolution of the microstructure and mechanical properties of the as-built alloy as a function of laser scanning speed. By elucidating the relationship between laser parameters, microstructure and mechanical properties, the objective is to provide fundamental guidance for tuning the solidification structures and mechanical properties of LPBF AlNiScZr alloys by selecting appropriate laser parameters.

Analysis of CFRP inter‐laminar cracking location under laser impacts

AbstractIn this study, a combination of theoretical analysis and experimental verification was used to investigate the effects of laser parameters and shock wave shape on the location of layer cracks in carbon fiber‐reinforced plastics specimens. Firstly, the propagation coupling process of trapezoidal, rectangular, and triangular pulses in the material was investigated based on the one‐dimensional stress wave propagation theory. The study analyzed the effects of shock wave pressure amplitude, pulse width, and other factors on the location of layer cracks in the material. Subsequently, laser impact experiments with varying energies and pulse widths were conducted on specimens of different thicknesses to investigate the impact of shock wave pressure amplitude and laser pulse width on the location of layer cracking. The results show that the theoretical analysis of triangular shock waves has broader applicability and can serve as a representative analytical model to describe single‐layer crack damage.Highlights Laser impact experiments with various specimen thicknesses. Laser pulse width determines the initial location of inter‐laminar cracking. The applicability of the triangular pulsed layer cracking formula. The effect of laser energy on pulse amplitude.

High-strength and impermeable sapphire/aluminum joints fabricated by ultrafast laser microwelding: Microstructures and joining mechanism

In this work, robust joints of sapphire and aluminum were successfully achieved by direct ultrafast laser transmission microwelding. Effects of laser parameters on the microstructures and mechanical properties were comprehensively studied. The welding process highly depended on the laser ablated metal nanoparticles within the heterojunction, as well as the thermal accumulation under multiple laser pulses irradiation. It showed that lack of fusion at the sapphire/aluminum interface can occur due to the incomplete melting of ablated nanoparticles at low laser fluence (<0.48 J/cm2). While serious cavities and cracks inside the brittle sapphire were formed with the intensified stress concentration after melting-solidification process at excessive laser fluence (>0.64 J/cm2). A nearly defect-free joint was obtained with max. shear strength of 128.1 ± 8.2 MPa at room temperature, when the laser fluence was 0.56 J/cm2. The high shear strength can be attributed to the tortuous interface with wide elemental transition layer. Meanwhile, the welded sapphire/aluminum joints exhibited high reliability under extreme service temperatures, which the shear strength can reach 159.8 ± 8.96 MPa at −50 °C and 80.6 ± 11.1 MPa at 200 °C. The sealing tests also showed the excellent impermeability of laser welded sapphire/aluminum structure, confirming the micro-crack free joint formation. This work demonstrates the feasibility of using ultrafast laser to achieve high-quality sapphire/aluminum joint, which is promising in heat-dissipation substrate manufacturing in power semiconductor devices.

Structural and chemical study of complex silver patterns additively manufactured by multi-photon reduction

Multi-photon reduction (MPR) based on femtosecond laser makes rapid prototyping and molding in micro-nano scale feasible, but is limited in material selectivity due to lack of the understanding of the reaction mechanism in MPR process. In this paper, additively manufacturing of complex silver-based patterns through MPR is demonstrated. The effects of laser parameters, including laser pulse energies and scanning speeds, on the structural and chemical characteristics of the printed structures are systematically investigated. The results show that the geometric size of printed cubes deviates from the designed size further by increasing laser pulse energy or decreasing scanning speed. The reaction mechanism of MPR is revealed by studying the elemental composition and chemical structures of printed cubes. The evolution of Raman spectra upon the laser processing parameters suggests that the MPR process mainly includes two processes: reduction and decomposition. In the MPR process, silver ions are reduced and grow into particles by accepting the electrons from ethonal molecules; meanwhile carboxyl groups in polyvinylpyrrolidone are decomposed and form amorphous carbon that is attached on the surface of silver particles. The conductivity of silver wires fabricated by MPR reaches 2 × 105 S m−1 and stays relatively constant as varying their cross section area, suggesting excellent electrical conduction. The understanding of the MPR process would accelerate the development of MPR technology and the implementation of MPR in micro-electromechanical systems could therefore be envisioned.

Nanosecond laser induced periodic silicon microstructures for broadband antireflective applications

Laser-driven micro/nano-texturing is a remarkably efficient and cost-effective technique, having diverse applicability in the realm of photonics, optoelectronics, and photovoltaics. Here, we demonstrate the high-intensity nanosecond laser-matter interactions for periodic micro/nanostructures on silicon, exclusively to emphasize the effects of laser parameters for large-scale integration. A wide range of periodic structure rapid fabrication over a wafer level is systematically studied for optimised parameters using nanosecond laser pulses (1064 nm, 50 ns) at different pulse repetition rates ranging from 10 to 40 kHz. A comprehensive understanding based on physical, structural, and optical studies reveals a strong correlation between the formation of nano/microstructure morphology and the laser parameters. The laser-matter interactions result in trench-like periodic patterns, formation of nanostructure agglomerations as light-trap-centres on the silicon surface. Such nano/micro periodic structures provide a dominant reduction in reflection losses of up to 80 % over a broad UV-NIR spectral region. The studies further demonstrate that the periodic structural patterns could also be potentially utilised for large-scale optical diffraction applications. In addition, the extra layer coating of Silicon Nitride (Si3N4) on the textured silicon further reduces the reflection losses, which is an added advantage of integrated silicon technology. The present work could open a commercial pathway for the rapid fabrication of nanosecond laser-based nanotexturing and periodic grating structures, enabling significantly reduced reflection and improved light trapping in large-scale Silicon-based applications due to its speed, repeatability, and high precision.

Comparative Numerical Analysis of Keyhole Shape and Penetration Depth in Laser Spot Welding of Aluminum with Power Wave Modulation

Keyhole mode laser welding is a valuable technique for welding thick materials in industrial applications. However, its susceptibility to fluctuations and instabilities poses challenges, leading to defects that compromise weld quality. Observing the keyhole during laser welding is challenging due to bright process radiation, and existing observation methods are complex and expensive. This paper alternatively presents a novel numerical modeling approach for laser spot welding of aluminum through a modified mixture theory, a modified level-set (LS) method, and a thermal enthalpy porosity technique. The effects of laser parameters on keyhole penetration depth are investigated, with a focus on laser power, spot radius, frequency, and pulse wave modulation in pulsed wave (PW) versus continuous wave (CW) laser welding. PW laser welding involves the careful modulation of power waves, specifically adjusting the pulse width, pulse number, and pulse shapes. Results indicate a greater than 80 percent increase in the keyhole penetration depth with higher laser power, pulse width, and pulse number, as well as decreased spot radius. Keyhole instabilities are also more pronounced with higher pulse width/numbers and frequencies. Notably, the rectangular pulse shape demonstrates substantially deeper penetration compared to CW welding and other pulse shapes. This study enhances understanding of weld pool dynamics and provides insights into optimizing laser welding parameters to mitigate defects and improve weld quality.

Significant improvement in surface hardness of CrMnFeCoNi high entropy alloy via nanosecond pulse laser grain refinement

The CrMnFeCoNi alloy with a stable single face-centered cubic (FCC) phase, representing a typical class of high-entropy alloys (HEAs), has garnered considerable attention owing to their exceptional mechanical properties. However, the inherent low hardness has impeded their utilization in structural or contact components. This study attempted to improve the surface hardness of CrMnFeCoNi HEA via grain refinement realized by nanosecond pulse laser irradiation. The effects of laser parameters on the surface microstructures, chemical composition, and mechanical properties were investigated, and the mechanism for grain refinement was analyzed. The experimental results showed that the hardness of the laser-irradiated surface was significantly improved without altering the chemical composition. This study provides a simple but effective method to refine the grain of HEAs and improve their surface hardness.

Repetitively pulsed streamer discharge with laser-induced surface trapped electron desorption to exploit residual charges in situ

Positive streamer behaviors under repetitive pulses are predominantly dependent on the availability of free electrons. If surface residual electrons stored from previous discharges could be intentionally released and involved into the next discharge, an alternative control freedom is provided apart from voltage waveform tailoring methods that mainly attract or repel gaseous residual charges. Evolutions of repetitively pulsed surface streamers in compressed (0.2 MPa) air were investigated after low-photon-energy pulsed visible (532 nm) and infrared (1064 nm) laser irradiations. Pulse-sequence and temporally resolved diagnostics were implemented to investigate effects of laser parameters (irradiation moment, wavelength, energy) and gas composition. A 2D surface streamer fluid simulation was performed to qualitatively unveil impacts of localized plasma patches. The surface streamer morphology and emission light are significantly and repeatably affected by the laser irradiation before the streamer inception, while, variations totally disappear without the solid surface. The secondary streamer is prolonged accompanied by a higher flashover probability after the pulsed laser irradiation in compressed air. Intriguingly, influences of the infrared laser persist for tens of microseconds before the next voltage pulse. Residual charge dynamics under the laser irradiation are analyzed, where the additional increase of O2− of low electron bound energy is emphasized. The laser induced surface trapped electron desorption is achieved through the direct or the step-wise process, dependent on the laser energy and the surface trap state distribution.

Fe‐Based Amorphous Alloy Coatings: A Review

Fe‐based amorphous alloy coatings (Fe‐AACs) have exhibited appropriate corrosion and wear resistance and improved the performance of material surfaces. This study summarizes the advances related to Fe‐based amorphous alloys pertaining to their chemical compositions and manufacturing processes and their associated effect on the amorphous structure, microstructure, and properties. In particular, Fe‐based amorphous alloy coatings produced by laser cladding are investigated to study the effect of amorphous structure, partial crystallization, and composition on the microstructure, hardness, corrosion, and wear resistance of these coatings. In addition, the effects of laser parameters (power and scanning speed) on the geometric and metallurgical characteristics of produced amorphous coatings are also covered.

Laser welding of pipe from steel 09G2S

Subject of research: laser welding of pipe steels. Purpose of research: variation of laser welding parameters to obtain optimal combinations of welded joints. Object of research: structure and properties of welded joints as a result of laser welding of pipe steel. Methods of research: optical microscopy, X-ray tomography and tensile tests were used to study the effect of laser parameters on the weld. Main results of research: the results of laser welding of tubing with different thickness by varying the power and parameters of laser radiation are presented. Possibilities of technology of laser welding of pipes with big thicknesses, with application of a filler wire are shown.

Laser-assisted (e,2e) study with twisted electron beam on H-atom

We study the laser-assisted twisted electron beam impact ionization of the hydrogen atom in coplanar asymmetric geometry. We develop the theoretical model in the first Born approximation. In the presence of the laser field, we treat the incident and scattered electrons as Volkov waves; the ejected electron, moving in the combined field of the laser and residual ion H+ , as a Coulomb–Volkov wave function. In this communication, we compare the angular profile of triple differential cross-section (TDCS) for laser-assisted twisted electron beam incidence with the plane-wave, laser-assisted plane wave, and field-free twisted electron beam for (e,2e) processes for different orbital angular momentum (OAM) number (ml ) values. We analyze the effect of impact-parameter b of twisted electron beam and the laser parameters on the angular distribution of the TDCS. We study the (TDCS)av for the macroscopic target to examine the effect of opening angle θ p of the twisted electron beam on the angular profile of TDCS. We also observe the influence of coherent superposition of two Bessel states on the angular profile of TDCS. Our results clearly show the effects of laser parameters (electric field ɛ and number of photon exchanged (l)) and twisted electron beam parameters (OAM number (ml ) and opening angle (θ p )) on the angular distribution of TDCS.

Laser drilling through Hashma sandstone

The application of laser in the drilling and perforation of oil wells can achieve great benefits such as reduced drilling costs and time with a higher rate of penetration (ROP) and elimination of casing necessity in oil and gas well drilling. This paper presents an original experimental investigation of Laser cutting through Hashma sandstone (a common quarry rock in Egypt) to develop a good understanding of the laser cutting process in sandstone. Five blocks of Hashma sandstone with dimensions of 35 cm × 35 cm × 10 cm were utilized to study the effects of the various parameters involved in the lasing (cutting) process in order to evaluate the cutting process through sandstone, investigate the effect of laser parameters on the process and the cutting mechanisms. The experimental results showed that the laser drilling can provide lower specific energy (SE) compared to conventional drilling methods, revealed the effect of various laser and rock parameters (such as beam power, intensity, duration, sample size, and orientation) on the cutting process, and demonstrated the laser cutting mechanisms through sandstone such as thermal spallation and melting mechanisms. Several parameters must be optimized for an optimum laser cutting process with the lowest SE, such as using the optimum beam power, beam duration (or Lasig time), and beam mode (continuous or pulsed). The optimum parameters may change from one case to another and depend on the overall interactions among the various variables such as thermal dissipation rate and purging system efficiency.

A new capacitive inductive system design for LASER-induced kilotesla magnetic field generation

This research focuses on exploring the nanosecond laser-driven coil systems capable of generating kT magnetic fields and the diverse applications of this system. Through investigating the effects of laser parameters and coil structures, the aim of this study is to unveil the physics of these generated intense magnetic fields. The outcomes gained from this research give an important and fundamental understanding on high magnetic field production, informing the development in laser-driven systems. The implications of this study extend to plasma physics, astrophysics simulations and fusion research. Furthermore, the study explains the advantages and applications of these intense magnetic fields and includes measurements of laser pulse powers according to coil materials.

Cost-effective fabrication of a high-conductivity copper electrode for heterojunction solar cells via laser-induced selective metallization.

Replacing expensive silver with inexpensive copper for the metallization of silicon wafer solar cells can lead to significant reductions in material costs associated with cell production, but the susceptibility of the Cu material to oxidation remains a challenging issue to solve. In this study, we investigate copper metallization of Indium Tin Oxide surfaces to define copper grid electrodes for heterojunction cells. We propose a novel laser-induced selective metallization (LISM) method to fabricate large-scale copper electrodes for heterojunction solar cells at low cost. This study includes a comprehensive evaluation of the morphological characteristics and electrical properties of the electrodes. The effects of laser parameters on the morphology, composition, size, and conductivity of copper electrodes are investigated. The goal of establishing the process window is to obtain the optimal laser parameters for manufacturing highly conductive copper electrodes. These optimized parameters will then be employed to fabricate high-performance electrodes for solar cells. Furthermore, a detailed analysis of the mechanism underlying laser selective metallization is provided. The resulting Cu electrodes exhibit high conductivity and low resistivity of 1.98 × 10-5Ω.cm, demonstrating the potential of this method for efficient and cost-effective solar electrode production.

Laser Texturing of Soda Lime Glass Surface for Hydrophobic Surface in Wenzel State

Glass surfaces tend to be hydrophilic when exposed to water resulting in a low water contact angle and high adhesion. Fabrication on a glass surface with low water adhesion can minimize the droplet’s adhesion conduct self-cleaning, and improve the cleanliness of the glass surface. This paper presents surface texturing of the soda-lime glass surface by laser processing three different patterns to improve water contact angle with low water adhesion on the modified glass surface. A design experiment method was developed to determine the effects of laser parameters on the glass surfaces. The laser parameters used are laser power between 0.45 and 1.05W and scanning speeds of 210, 420, and 600 mm/min. The effects of laser parameters on surface morphology, water contact angle measurement, and average surface roughness, Ra were investigated. The characterization was conducted for surface morphology, two-dimensional surface roughness profile, and water contact angle. The results show that the highest water contact angle obtained after laser texturing is up to 125.29° compared to the as-received surface with a contact angle of 32.35°. The highest water contact angle resulted from 420 mm/min scanning speed and 0.45 W of laser power, responding to the surface with a minimum range of Rax and Ray of 0.96 and 1.5 μm. These findings are significant for designing surface modification of self-cleaning glass surface applications like the automotive windscreens, and window panels for high-rise buildings.

Lipophilic and friction properties of 20CrMnTi steel with laser-induced texturing

Laser surface texturing is an effective method to enhance gear lubrication by improving lipophilic properties, thereby increasing transmission performance and longevity. This study investigated the effects of laser parameters on lipophilicity using a grid texture and found that a scanning speed of 100 mm/s maximized diffusion and climbing. The textured specimens showed higher wetting hysteresis and adsorption, forming a thicker oil film for better lubrication. Wear tests indicated that the textured specimen had reduced friction, wear quality, and depth by 49.2% and 66.34% compared to unprocessed specimens. Gear efficiency is effectively increased, and gear oil temperature is significantly reduced. This research offers insights into lipophilic characterization and gear lubrication enhancement, potentially decreasing surface failures like pitting, adhesion, and wear.

Optimization of Laser Cutting Parameters for PMMA Using Metaheuristic Algorithms

This study fixates on determining the optimum laser input parameters that simultaneously meet the desired kerf width and depth during CO2 laser cutting of various polymethylmethacrylate (PMMA) sheets. It has three contributions. The first is to model the cutting process of PMMA by polynomial curve fitting as a function of laser power, laser speed, and standoff distance. R-squared (R2), adjusted R2 and root-mean-square error (RMSE) criteria were taken into account to measure the performance of the proposed model. The effect of laser parameters on the process is investigated by analysis of variance (ANOVA) and sensitivity analysis. The second is to optimize the derived nonlinear regression models using genetic algorithm (GA), particle swarm optimization (PSO), whale optimization algorithm (WOA) and ant lion optimization (ALO) metaheuristic methods and compare the performances of the algorithms. The third is to compare the adequacy of the optimization process with the artificial neural network (ANN). The investigations exhibited that the best-fitting polynomials are obtained with the R2 and adjusted R2 values of over 99% and 97%, respectively. ANOVA and sensitivity test revealed that the sensitivity of the laser power, which is the most effective parameter, was 150 at low powers and decreased to 0 as the power value increased. When the nozzle distance is 4.1, the proposed metaheuristics gave effective and sufficiently accurate results. PSO stood out in terms of both best cost value (3.49 × 10–8) and relative error value (0.19%). The relative error of the ANN was found as 3% in terms of kerf depth.