CO2 Laser Beam Research Articles

The diamond-silicon carbide composite Skeleton® as a promising material for substrates of intense X-ray beam optics.

The paper considers the possibility of using the diamond-silicon carbide composite Skeleton® with a technological coating of polycrystalline silicon as a substrate for X-ray mirrors used with powerful synchrotron radiation sources (third+ and fourth generation). Samples were studied after polishing to provide the following surface parameters: root-mean-square flatness ≃ 50 nm, micro-roughness on the frame 2 µm × 2 µm σ ≃ 0.15 nm. The heat capacity, thermal conductivity and coefficient of linear thermal expansion were investigated. For comparison, a monocrystalline silicon sample was studied under the same conditions using the same methods. The value of the coefficient of linear thermal expansion turned out to be higher than that of monocrystalline silicon and amounted to 4.3 × 10-6 K-1, and the values of thermal conductivity (5.0 W cm-1 K-1) and heat capacity (1.2 J K-1 g-1) also exceeded the values for Si. Thermally induced deformations of both Skeleton® and monocrystalline silicon samples under irradiation with a CO2 laser beam have also been experimentally studied. Taking into account the obtained thermophysical constants, the calculation of thermally induced deformation under irradiation with hard (20 keV) X-rays showed almost three times less deformation of the Skeleton® sample than of the monocrystalline silicon sample.

Elevated temperature rusting characteristics of UNS 31254 weldments within the operational confines of fossil fuel-fired plants and municipal waste incinerator surroundings at 700 °C

ABSTRACT This study investigates the air oxidation and rusting traits of fully austenitic alloy 254 stainless steel samples at 700°C after pulse current gas tungsten arc welding (PCGTA) and CO2 laser beam welding (CO2 LBW), with or without molten salt, relevant to coal-fired plants and waste incinerator settings. Among the weldments studied, CO2 laser weldments demonstrate greater resilience to corrosive gas and salt amalgamation, as well as air oxidation, compared to gas tungsten arc weldments, possibly due to thermal disparities and microstructural differences inherent in the welding processes. Protective oxides enhance corrosion resistance in air-oxidised samples, while corrosive compounds like CrS, Cr2K2O7, etc., reduce corrosion resistance and promote spallation in salt-degraded material. A thermogravimetric approach was used to assess rusting effects, alongside microstructural analysis employing optical, Scanning electron microscopy/ Energy dispersive x-ray spectroscopy (SEM/EDS), and X-Ray diffraction analysis (XRD) techniques.

The phenomenon of skin contraction in CO2 LASER surgical incisions using superpulse and continuous emission mode - preliminary study.

The skin contraction phenomenon occurs due to the energy emitted by the surgical CO2 LASER affecting the collagen architecture and intracellular water content in tissues. The study aimed to assess how gender, age, breed, body-weight, CO2 LASER emission mode, and potency influence skin contraction following the incision. The study involved 80 dogs (N = 80) of both genders, multiple breeds, undergoing major surgery with CO2 LASER. Subjects were grouped based on LASER potency (12 or 15 Watts) and emission mode (Superpulse-SP or Continuous-CT): GSP12, GSP15, GCT12, and GCT15. A 10mm incision was performed using the surgical CO2 LASER beam, consistently employing a focal point of 0.4mm, positioned at a distance of 1mm from the skin surface, and always maintained perpendicular to it, and resulting lengths measured with a digital caliper. Results were considered significant for p-value < 0.05. GSP12 showed minimal contraction, while GCT15 exhibited the most significant. Male subjects in GCT12, GCT15, and GSP12 experienced less contraction than females. Purebred dogs had greater contraction than mixed breeds. GSP12 individuals showed age-related contraction decrease (p < 0.01), with skin contracting by 0.09mm per year. Weight and skin contraction trended towards significance (p = 0.06), with a 0.02mm increase per unit weight. For a constant power of 12 W, the analysis of the relationship between the emission mode of the LASER beam and the final skin contraction (GSP12 vs. GCT12) revealed statistically significant differences (p < 0.01). This study suggests that the use of the Continuous mode of LASER emission, regardless of the power used, is associated with a higher level of final skin contraction. TRIAL REGISTRATION NUMBER AND DATE OF REGISTRATION FOR PROSPECTIVELY REGISTERED TRIALS: Project approval registration number by the Research and Teaching Ethics Committee (CEIE),Faculty of Veterinary Medicine-University of Lisbon (FMV_ULisboa), Lisboa-Portugal, N/Refª 015/2022.

Mechanical properties of CO2 laser beam butt-welded plates of Hastelloy c-276

In the current investigation, thermo-mechanical analysis is carried out for Hastelloy C-276 using laser beam welded butt joints. The Gaussian heat source model is used for transient thermal analysis, and the maximum temperature at the weld area resulted in residual stresses within safe limits. To validate, the experimentation was carried out with CO2 Laser beam welding using an L4 orthogonal array. Sample 2 had the least-residual stresses in the weldment, and the mechanical and metallurgical properties studies were carried out. The residual stress distribution was measured using X-ray diffraction and was acceptable within the yield limits of the material. Finite Element Analysis (FEA) and experimental residual stresses were compared; the FOS was 2.088, and the remaining samples were more than 2.0 compared to the base material tensile strength. Tensile tests confirmed that the strength of the weld zone is higher than that of the parent metals.

Flexible and freestanding temperature sensors based on laser carbonization of carbon nanofibers

A new single-step, low-cost method for producing a wearable, flexible temperature sensor has been developed using laser writing technology. The process involves carbonizing and patterning polymeric nanofibers to create a standalone laser-carbonized nanofibers (LCNFs) substrate. A large-area polyacrylonitrile nanofibers mat is first prepared using electrospinning and then carbonized with a high-power CO2 laser beam. The resulting LCNFs are highly conductive and retain their fibrous structure. The near-complete disappearance of polyacrylonitrile peaks in the FTIR measurements and the high-intensity characteristic peaks of carbon materials obtained in the Raman scattering measurements of the LCNFs confirm their complete carbonization. SEM microscopy showed that the fibrous structure of the LCNFs remained intact after the laser carbonization process with no significant damage. Additionally, TEM microscopy revealed that the LCNFs are made up of axially ordered graphene sheets, which form their unique fibrous structure. LCNFs' temperature sensor exhibits >87% higher temperature coefficient of resistance (TCR) than laser-induced graphene (LIG) temperature sensor on a polyamide substrate when tested under the same experimental conditions. The LCNFs sensor also boasts excellent resistance stability, mechanical stability, and flexibility. To fit various wearable applications and enhance the temperature-sensing capabilities, three different sensor patterns of LCNFs were created: square, serpentine, and heater. Among these patterns, the heater design exhibited superior TCR and temperature response. However, it also had a higher thermal mass compared to the other patterns.

Dual-wavelength lasing at ∼1.2 μm and ∼2.0 μm in a Ho3+-doped fluoroaluminate glass microsphere

This study presents the experimental realization of a microsphere laser resonator designed to operate within the approximate wavelength range of 1.2 μm and 2.0 μm. This resonator, employing a Ho3+-doped fluoroaluminate glass microsphere, was stimulated by a 1150 nm laser, marking the first demonstration of its kind. The observed laser emissions at ∼1.2 μm and ∼2.0 μm were ascribed to the transitions of Ho3+ ions, specifically 5I6 → 5I8 and 5I7 → 5I8, respectively. The fabrication of the microsphere, possessing a characteristic diameter of approximately 50 μm, entailed the controlled melting of a fluoroaluminate glass filament through the application of a focused CO2 laser beam. Concurrently, a tapered fiber with a waist diameter of ∼2 μm was created by subjecting a standard silica single-mode fiber to a process of controlled heating and stretching. The findings of this investigation suggest promising prospects for the development of multi-wavelength lasers utilizing fluoroaluminate glass microspheres, particularly in intricate environmental settings.

Configurable SNAP microresonators induced by axial pre-strain-assisted CO2 laser exposure.

Flexible engineering of the complex shapes of the surface nanoscale axial photonics (SNAP) bottle microresonators (SBMs) is challenging for future nanophotonic technology applications. Here, we experimentally propose a powerful approach for the one-step fabrication of SBMs with simultaneous negative and positive radius variations, exhibiting a distinctive "bump-well-bump" profile. It is executed by utilizing two focused and symmetrical CO2 laser beams exposed on the fiber surface for only several hundred milliseconds. The spectral characteristics of different eigenmodes are analyzed, providing deep insights into the complex physical processes during the CO2 laser exposure. The shapes of the SBMs can be flexibly adjusted by the exposure time, laser power, and applied pre-strains. As a proof of this technique, the developed approach enables the efficient production of a bat SBM, ensuring a uniform field amplitude of the bat mode over the length exceeding 120 µm with 7% deviation. Our proposed technique provides a powerful technique for the efficient fabrication of SBMs with predetermined shapes, laying the groundwork for its applications on microscale optical signal processing, quantum computing, and so on.

Optimizing CO2 laser beam welding parameters for magnesium hybrid metal matrix composites (ZE41A)

ABSTRACT The current work is the investigation of optimizing input welding parameters of CO2 laser welding of two stir squeeze casted magnesium (ZE41A) matrix silicon nitride and alumina-reinforced hybrid metal matrix composites (MMCs). Two similar hybrid MMC plates were joined by the CO2 laser beam welding process and were investigated for input welding parameters influencing the metallurgical and mechanical properties. The identified parameters were subjected to optimization by Box-Behnken experimental design of Response Surface Methodology (RSM) and the experimental trials were validated by Analysis of Variance (ANOVA). With increases of 16% and 23%, the microhardness and tensile strength peaked at 207 MPa and 78 HV, respectively. The ideal input welding settings were 3500W of laser power, 4 mm/minute welding speed, and a focus length of 1.5 mm.

Process Parameter Optimization for CO2 Laser Polishing of Fused Silica Using the Taguchi Method.

Fused silica was polished to a high quality by a CO2 laser beam with a rapid scanning rate. The rapid scanning rate produced a line laser heat source, resulting in a "polishing line" during the polishing process. The Taguchi method was used to evaluate the comprehensive influence of polishing process parameters on the polishing qualities. Four factors, namely the length of laser reciprocating scanning (A), laser beam scanning speed (B), feed speed (C), and defocusing amount (D), were investigated in this study. The optimal process parameter combination (A1B1C1D1) was obtained. The surface roughness of fused silica was reduced from Ra = 0.157 μm to 0.005 μm. Through analysis of variance (ANOVA), it was found that laser beam scanning speed (B) had a significant influence on the polishing quality. The interaction of the two factors plays a decisive role in the determination of the best process parameters, and the influence of other multi-factor interaction can be ignored; the interaction between A × B is the largest, with a contribution of 42.69%.

Fabrication of PEEK Ag/AgI mid-infrared hollow fiber and transmission reliability study for CO2 laser radiation

Hollow fiber is a crucial means for delivery of mid-infrared laser radiation and has a wide range of applications in laser surgery and other fields. At present, there is still a lack of low-cost, highly flexible plastic hollow fiber that can reliably transmit mid-infrared laser with low loss. In this study, flexible Poly ether ether ketone (PEEK) tubing material was selected as the structural tube for establishing a robust plastic Ag/AgI mid-infrared hollow fiber. Fiber samples with inner diameters of 1.0, 1.5 and 2.0 mm were prepared using plasma treatment and dynamic chemical liquid deposition processes. The transmission losses for CO2 laser of the 1.0-, 1.5- and 2.0-mm-bore PEEK Ag/AgI hollow fibers increased from 0.40, 0.18 and 0.10 dB/m to 2.35, 1.60 and 1.05 dB/m, respectively, as they were bent at an angle from 0° to 180° with a radius of 15 cm. The hollow fibers could stably transmit CO2 laser in high (120 °C) and low (-78.5 °C) temperature environments. After undergoing 100 h of accelerated humidity-heat aging (85 °C, 85 % RH) and 10 cycles of high-low (-40 ∼ 85 °C) temperature cycling treatment, the transmission loss remained almost unchanged. The PEEK Ag/AgI hollow fiber exhibited high energy damage threshold and it could stably deliver a 10 ∼ 20 W CO2 laser beam for 20 min to 5 h when bent at a 25 cm radius and a 90° angle. The current research provides a possible approach for developing low-cost, highly flexible, low-loss and highly reliable mid-infrared hollow fibers. It is helpful to promote the applications of CO2 laser in laser medicine, intelligent manufacturing and sensing.

Laser-induced carbonization of carbon nanofibers free-standing electrodes for flexible interdigitated micro-supercapacitors

A versatile one-step laser writing technique is introduced in this work for carbonizing and patterning polymeric nanofibers mat to produce a free-standing laser carbonized nanofibers (LCNFs) electrode for flexible interdigitated microsupercapacitors. A large-area polyacrylonitrile nanofibers mat was first prepared with the facile electrospinning technique on a collecting drum followed by a stabilizing step. A high-power CO2 laser beam is used to carbonize the stabilized nanofibers into highly conductive LCNFs at ambient atmospheric conditions and draw the interdigitated pattern at the same time. The complete carbonization of the nanofibers is confirmed by the nearly complete disappearance of polyacrylonitrile peaks in the FTIR measurements and from the high-intensity characteristic peaks of carbon materials obtained in the Raman scattering measurements of the LCNFs. The SEM microscopy showed that the LCNFs were able to survive their fibrous structure after the laser carbonization process and without any significant damage. Also, the TEM microscopy revealed that the LCNFs are composed of graphene sheets that are axially ordered to form such a unique fibrous structure. Owing to its outstanding structural and electrical properties, the LCNFs interdigitated supercapacitor attained an aerial specific capacitance of 20.38 mF/cm2, a high energy density of 0.64 μWh/cm2, and a high-power density of 224.6 μW/cm2 which are almost two-fold higher than those of the laser-induced graphene (LIG) on a polyamide substrate assembled with the same conditions. This was accompanied by an excellent capacitance retention of 95.3 % after 10,000 electrochemical cyclic stability and impressive mechanical stability and flexibility.

Microstructure and tensile behavior of CO2 laser beam welded AISI 409 ferritic stainless steel tubes

Laser beam welding (LBW) is a suitable process to join ferritic stainless steels (FSS). LBW process helps to suppress grain growth and intermetallic phases. CO2-based laser source was used to join AISI 409 FSS tubes having a thickness of 4 mm. The laser scanning speed, which determines the production rate, was varied from 1.3 m/min to 3.3 m/min. There were no defects at the joint region except an undercut at the highest scanning speed. The micrographs showed no coarsening of grains at HAZ. The fusion zone showed a dendritic structure composed of columnar grains and axial grains. The increase in scanning speed refined the dendritic structure. The fusion zone experienced phase transformation from δ ferrite to martensite. TEM micrographs revealed the formation of substructures and dislocation fields. The microstructural changes caused the strengthening of the fusion zone. The joint strength in most of the weldment reached the strength of the base metal. All the joints failed in a ductile manner and the elongation was more than 10%.

Waveguide mode of drilling high-aspect ratio holes in PMMA by CO laser beam

Experimental results on drilling of PMMA by mid-IR lasers are presented and discussed. Proper choice of a CO laser beam focusing conditions made it possible to produce high aspect ratio (∼100) holes. During the laser drilling a waveguide-like structure of the hole was formed in PMMA with almost a constant sub-millimeter diameter along its whole length. Characteristics of the holes drilled by CO laser (wavelength 5.0–5.5 µm) and CO2 laser (10.6 µm) beams are compared.

Drilling of cylindrical holes in Crown glass by a short-pulse flat-top CO2 laser beam

We investigated cylindrical hole drilling in a crown glass with a high thermal expansion coefficient of 94 × 10–7 K−1 and a low melting point of 724 °C using a short-pulse CO2 laser with a flat-top beam, and also examined the drilling characteristics. The short laser pulse consisted of a pulse spike with a pulse width of 276 ns and a pulse tail with a length of 56.9 µs at a repetition rate of 200 Hz. The laser beam had a flat-top profile with an estimated M2 parameter of 13.5 and a diameter of 12.5 mm before a focusing lens. The flat-top beam was focused by the focusing lens, which had a focal length of 12.7 mm, on the glass surface at a focus offset of −0.20 mm to +0.40 mm. The incident flat-top beam produced conical holes at focus offsets of −0.20 mm to 0.00 mm and produced cylindrical holes at focus offsets of +0.20 mm to +0.40 mm. The hole depth of the cylindrical holes was 109 μm to 434 μm, the surface hole diameter was 150 μm to 366 μm, and the aspect ratio, defined as the ratio of the hole depth to the surface hole diameter, was 0.30 to 2.89. The hole depth was influenced by the focus offset and the total irradiation fluence, whereas the surface hole diameter, the taper angle and the ratio of the surface hole diameter to the irradiation diameter were influenced by the focus offset only. The ratio of the surface HAZ (Heat affected zone) diameter to the irradiation diameter was influenced by both the focus offset and the total irradiation fluence.

Fabrication of Spiral Low-Cost Microchannel with Trapezoidal Cross Section for Cell Separation Using a Grayscale Approach.

Trapezoidal cross-sectional spiral microfluidic channels showed high resolution and throughput in cell separation in bio-applications. The main challenges are the complexity and high cost of the fabrication process of trapezoidal cross-sectional channels on the micro-scale. In this work, we present the application of grayscale in microfluidic channel design to overcome the complexity of the fabrication process. We also use direct engraving with a CO2 laser beam on polymethyl methacrylate (PMMA) material to drastically reduce the microfluidic chip's cost (to <30 cents) and fabrication time (to 20 min). The capability of the present fabrication methodology for cell sorting applications is demonstrated through experimental tests for the separation of white blood cells (WBCs) from whole blood at different dilution factors. The experimental results indicated that an 800 µL/min flow rate provided the optimal separation efficiency using the fabricated chip. A 90.14% separation efficiency at 1% hematocrit diluted blood sample was reported.

Influence of CO2 laser beam modelling on electronic and electrochemical properties of paper-based laser-induced graphene for disposable pH electrochemical sensors

Laser-induced graphene (LIG) allows for the fabrication of cost-effective, flexible electrodes on a multitude of recyclable and sustainable substrates, for implementation within electrochemical biosensors. This work expands on current LIG research, by experimentally modeling the effects of several CO2 laser irradiation variables towards resulting conductive and electrochemical properties of paper-derived LIG. Instead of relying on the established paradigm of manipulating power and scan speed of the laser irradiation process for optimized outcomes, modeling of underlying laser operation principles for pulse modulation, regarding pulse repetition frequencies, pulse duration and defocus are presented as the key aspects dominating graphitization processes of materials. This approach shows that graphitization is dominated by appropriate pulse durations, dictating the time the substrate is exposed to each laser pulse, with laser fluence and irradiation defocus influencing the resulting conductive properties, with sheet resistances as low as 14 Ω sq−1. Similarly, fabrication settings controlled by these parameters have a direct influence on the properties of LIG-based electrochemical three-electrode cells, with optimized fabrication settings reaching electrochemically active surface area as high as 35 mm2 and heterogeneous electron transfer rates of 3.4 × 10−3 cm.s−1. As a proof-of-concept, the production of environmentally friendly, accessible, and biocompatible pH sensors is demonstrated, using two modification approaches, employing riboflavin and polyaniline as pH-sensitive elements.

An Overview Study on Laser Technology and Conventional Technology’s Effect on Wood and Sheet Metal Manufacturing for The Furniture Industry

The laser was one of the most important inventions of the twentieth century, improving many aspects of daily life. Because of its clean cutting-edge capabilities, delicate welding lines, potent etching strokes, high power operation, and precise distance measurement capabilities, laser technology has gradually taken over and dominated the mechanical market, particularly in the field of material handling and metal parts for the furniture industry. By creating intricate and continuous features, lines, shapes, and patterns in metal using lasers, the wood, and sheet metal furniture industries are given new opportunities. However, it is still confusing for designers and manufacturers which is the best method to produce their designs. Hence, there is a need to compare the conventional technology of traded furniture production with laser technology. In order to support the industry in a way that serves to save time and effort and enhances sustainability. We demonstrate that using laser cutting and engraving devices in intricate and sophisticated processing is an amazing technology on flat sheet materials. In conclusion, the laser is more flexible in conjugation with a high degree of accuracy, and the quality of the cutting kerf all add up to make the use of this tool particularly interesting for machining. The focused beam of a modern CO2 laser cuts wood and metal sheets quickly, and accurately and requires no contact or clamping. There is no tool wear and the laser is more or less maintenance-free. Otherwise, using a CNC router is preferred when cutting, or engraving in case of thick wood or metals sheet.

Optimization of laser machining parameters of SS 314 using response surface methodology

Stainless steel (SS) is an essential industrial and structural material that is challenging to be machined by conventional methods due to its very high melting temperature and the oxides that are formed. Still, as an alternate method, it can be machined by a laser. The primary objective of the current study is to optimize the CO2 laser beam cutting process parameters (viz. are (i) laser power, (ii) cutting speed, and (iii) gas pressure) on surface characteristics of machining 5 mm Stainless Steel (SS 314). Using Response Surface Methodology (RSM) optimization approach and the Box Behnken method, the process parameter of laser cutting were optimized while minimizing the surface roughness. RSM suggested a quadratic regression equation for surface roughness prediction in terms of process parameters. The optimum process parameters obtained are laser power = 1.2 kW, gas pressure = 0.579 bar, and the cutting speed = 2.4 m/min, which results in surface roughness of 2.132 µm.

Sensitivity enhancement of gold nanospheres assisted CO2 laser tapered optical fiber for refractive index sensor

Tapered optical fibers (TOFs) have been intensively used as sensors due to their high sensitivity, simple structure, and excellent coupling efficiency. In this paper, we reported the successful rapid tapering of single mode and multimode fibers using CO2 laser beam at working wavelength of 10.6 μm. Clean and symmetric tapers could be produced in just 5 s using this method. Arduino-based microcontroller was included in the tapering set-up to precisely control the fiber pulling speed and distance. Smaller waist diameters that were observed in multimode than in single mode fibers generated more evanescent waves on the cladding of tapered multimode fibers (TMMFs). This implied that TMMFs performed better refractive index (RI) sensitivity, within the range of 1.3325–1.4266, than tapered single mode fibers (TSMFs). Furthermore, localized surface plasmon resonance (LSPR) effect was coupled with evanescent wave through AuNSs immobilization on the TOF surface. The AuNSs having average particle diameter of 12.70 nm was synthesized by citrate reduction route. The formation of AuNSs was confirmed by (ultraviolet–visible) UV–vis and high-resolution transmission electron microscopy (HRTEM) data. Self-assembly monolayer approach was conducted to immobilize AuNSs on the 3-mercaptopropyl trimethoxysilane (MPTMS)-functionalized surface of the TOFs. The AuNSs immobilization on TMMFs could improve the sensitivity up to 122 %. Besides sensitive to RI changes, the sensors were also excellent in terms of repeatability and reversibility performances. Finally, this paper described the amplitude modality-based RI sensing mechanism due to evanescent wave and LSPR effects.

Microstructure and electrical characterizations of CuO/Fe2O3 ceramics sintered by CO2 laser beams

Layers of CuO/Fe2O3 mixture powders in a Cu/Fe molar ratio of 1:1 irradiated by continuous-wave CO2 laser beams in air transformed into face-centered-cubic Cu0.67Fe2.33O4 or CuFe5O8. The uneven or wavy surface with precursor residues after laser sintering was attributed to the intrinsic Gaussian beam profile and the temperature-induced tension gradient in the melt pool. The center valleys of the laser tracks exhibited larger faceted particles and more circular voids than those in the edge peaks. The nonstoichiometric phase transformation to Cu0.67Fe2.33O4 or CuFe5O8 grains and the formation of Cu2O along the grain boundaries can be seen in the X-ray diffraction patterns and transmission electron microscopic images. Microstructure characterizations via selected area electron diffraction revealed a preferred growth direction of <111> and coherent interfaces between the CO2 laser sintered Cu0.67Fe2.33O4 or CuFe5O8 grains and precipitated Cu2O due to a small lattice mismatch. The electrical voltage sweep measurements showed the resistivity in the range of 1.5 × 10−5–1.5 × 10−4 Ω ∙ m in the center valleys, indicating their potential applications on sensors, thermistor, and thermoelectric materials.