Low Power CO2 Laser Research Articles

Design of compact dispersion interferometer with a high efficiency nonlinear crystal and a low power CO2 laser

When the electron density of a plasma generated in high pressure environment is measured by a conventional interferometer, the phase shifts due to changes of the neutral gas density cause significant measurement errors. A dispersion interferometer, which measures the phase shift that arises from dispersion of medium between the fundamental and the second harmonic wavelengths of laser light, can suppress the measured phase shift due to the variations of neutral gas density. In recent years, the CO2 laser dispersion interferometer has been applied to the atmospheric pressure plasmas and its feasibility has been demonstrated. By combining a low power laser and a high efficiency nonlinear crystal for the second harmonic component generation, a compact dispersion interferometer can be designed. The optical design and preliminary experiments are conducted.

Enhancement of low power CO2 laser cutting process for injection molded polycarbonate

Laser cutting technology is a non-contact process that typically is used for industrial manufacturing applications. Laser cut quality is strongly influenced by the cutting processing parameters. In this research, CO2 laser cutting specifications have been investigated by using design of experiments (DOE) with considering laser cutting speed, laser power and focal plane position as process input parameters and kerf geometry dimensions (i.e. top and bottom kerf width, ratio of the upper kerf to lower kerf, upper heat affected zone (HAZ)) and surface roughness of the kerf wall as process output responses. A 60 Watts CO2 laser cutting machine is used for cutting the injection molded samples of polycarbonate sheet with the thickness of 3.2mm. Results reveal that by decreasing the laser focal plane position and laser power, the bottom kerf width will be decreased. Also the bottom kerf width decreases by increasing the cutting speed. As a general result, locating the laser spot point in the depth of the workpiece the laser cutting quality increases. Minimum value of the responses (top kerf, heat affected zone, ratio of the upper kerf to lower kerf, and surface roughness) are considered as optimization criteria. Validating the theoretical results using the experimental tests is carried out in order to analyze the results obtained via software.

Analisis Fabrikasi Desain Passive Mixing Microchannel Perangkat Mikrofluidik Material Acrylic Dengan Laser CO2 Daya Rendah

Microfluidics devices have been applied in the biomedical field to manipulate the tissue fluids in channels with dimensions between 5-500 lm. Microfluidics device manufactured by a microfabrication process consisting of design, microstucturing and back-end processes. One application of microfluidics is a passive mixing microchannel. In this device, the liquid will flow through the channel without any moving parts and the pressure from the outside to produce a fluid mixing. It is important to design the shape of the channel to generate a nice passive mixing microchannel. Low power CO2 laser is used to process microstucturing as cutting tools to produce microfluidic devices on acyilic material. Surface roughness lines were designed to be observed. In this study, the design process channel carried by the experimental method through the parameters that affect the output of the process is the power of laser cutting, cutting speed and design channel. And then the fabrication of microfluidics with back-end processing is done by the process of merging with a thermal bonding method. Finally, From the experimental results, the design of the channel 1 has an influence on all the parameters for surface roughness compared with a channel design 2.

Low power CO2 laser modified iron/nickel alloyed pure aluminum surface: Evaluation of structural and mechanical properties

Surface modification of metals is demanding for high strength industrial purposes. Weak mechanical properties of aluminum (Al) are disadvantageous for several applications and needs improvement. We modify the surface of pure Al substrate by alloying it with a thick layer of Fe-Ni, where a low power (27 watt) cw CO2 laser with varying exposure time (30, 40 and 50s) is used. The exposure time dependent microstructure, surface morphology, and surface hardness of the achieved inter-metallic alloyed samples are determined. Microstructure analysis revealed the formation of different phases (Al0.9Ni1.1, AlNi3, Al6Fe, AlFe3, Al5Fe2 and Al76.8Fe14, Al5FeNi) with chemical heterogeneity. Alloyed sample displayed enhanced surface hardness (varied from 27HV0.1 to 53.9HV0.1) for extended laser radiation exposure time (from 30 to 50s). A new inter-metallic compound aluminum-iron-nickel (Al-Fe-Ni) with considerably tougher surface is achieved. Our observations may contribute towards the development of laser assisted modification of metal surface alloying.

Fabrication of a microtoroidal resonator with picometer precise resonant wavelength.

Fabricating an optical microresonator with precise resonant wavelength is of significant importance for fundamental research and practical applications. Here, we develop an effective method to fabricate ultra-high Q microtoroid with picometer-precise resonant wavelength. Our method adds a tuning reflow process, using low-power CO2 laser pulses, to the traditional fabrication process. It can tailor resonant wavelength to a red or blue direction by choosing a proper laser power. Also, this shift can be controlled by the exposure time. Meanwhile, quality factor remains nearly unchanged during this tailoring process. Our method can greatly reduce the difficulties of experiments where precise resonances are required.

Fabrication of microchannels on PMMA using a low power CO2 laser

This study presents a cheap and quick method for the formation of microchannels on poly methyl methacrylate (PMMA). A continuous wave CO2 laser with a wavelength of 10.6 μm was used to inscribe periodic ripple structures on a PMMA substrate. A direct writing technique was employed for micromachining. As PMMA is very sensitive to such laser irradiations, a slightly low power CO2 laser was effective in inscribing such periodic structures. The results show that smooth and fine ripple structures can be fabricated by controlling the input laser parameters and interaction time of the laser beam. This direct laser writing technique is promising enough to prevent us from using complex optical arrangements. Laser power was tested starting from the ablation threshold and was gradually increased, together with the variation in scanning speed of the xy-translational stage, to observe the effects on the target surface in terms of depth and width of trenches. It was observed that the depth of the trenches increases on increasing the laser power, and the bulge formation on the outer sides of the trenches was also studied. It was evident that the formation of bulges across the trenches is dependent on the scanning speed and input laser power. The results depict that a focused laser beam with optimized parameters, such as controlling the scanning speed and laser power, results in fine, regular and tidy periodic structures.

Analisis Fabrikasi Desain Lamination Passive Mixing Microchannel Perangkat Mikrofluidik AcrylicMenggunakan Laser CO Daya Rendah

Microfluidics device has been applied in the biomedical fields to manipulate fluids in a channel network with the dimensions between 5-500 µm. Microfluidics device is manufactured by microfabrication process consists ofdesign, microstucturing and back-end process. One of microfluidics application is passive mixing microchannel. Inthis device, the fluids will flow through the channel without any moving part and pressure from outside to producemixing fluid. It is important to design the form of channel to produce a good lamination passive mixingmicrochannel. In this study, the process of channel design was performed. Low power CO2 laser was used formicrostucturing process as a cutting tool to produce microfluidic device on acrylic material. The parameters affectthe output of the cutting process are the laser power, cutting speed and the design of channel. Surface roughness ofdesigned channel was observed. Finally, back-end process was performed by joining process using thermalbonding method. From the experimental results, the design of lamination channel has an influence on allparameters to the surface roughnes.

Characterization of the absorptance of laser irradiated steel sheets

This work presents an experimental-numerical methodology aimed at deriving the absorptance of both a low output power CO2 laser beam and a Yb fiber laser beam applied to an AISI 304 stainless steel cold-rolled sheet under two different conditions of the sample surface: without and with a spray graphite coating. The absorptance values were obtained by minimizing the error between temperature evolution measurements at various locations of the irradiated sheet and the corresponding finite element predictions. The values obtained for the CO2 laser were a = 0.20 for the stainless steel and a = 0.41 for the graphite coating. For the Yb fiber laser, the values were a = 0.40 for the stainless steel and a = 0.64 for the graphite coating. Degradation of the graphite layer was observed when the resistance temperature of the graphite coating was exceeded.

EXPERIMENTAL STUDY ON THE CO2 LASER CUTTING OF NOVEL POLYAMIDE 6/FLUOROELASTOMER THERMOPLASTIC ELASTOMERIC BLENDS

ABSTRACT The application of the low-power CO2 laser-cutting process to fluoroelastomer (FKM), polyamide 6 (PA6), PA6/FKM thermoplastic elastomers (TPEs), and their thermoplastic vulcanizate (TPV) is reported. The main laser process parameters studied were laser power, cutting speed, and material thickness. The value of the top and bottom widths of the slit that were formed during laser cutting (kerf width), melted transverse area, and melted volume per unit time were measured and analyzed. Interestingly, TPE showed a smaller melted area and melted volume per unit time when compared with those values with PA6. Dynamic vulcanization further decreased these values. For example, the melted areas of PA6 and TPE were 510 × 10−3 mm2 and 305 × 10−3 mm2, respectively, which reduced to 238 × 10−3 mm2 for TPV at 40 W laser power. FKM showed the lowest value (melted area of 180 × 10−3 mm2). In addition, the output quality of the cut surface was examined by measuring the root mean square (RMS) roughness of the cut edges and heat-affected zone (HAZ). The obtained results indicated that the dimension of the HAZ and RMS roughness largely decreased in TPE when compared with PA6. For example, the HAZ of PA6 was 700 μm, which decreased to 230 μm for TPE at 40 W laser power. On the other hand, HAZ was nonexistent for FKM. Infrared spectroscopic analysis showed that there was no structural change of TPE or pristine polymers after applying the low-power CO2 laser on the surface of materials. CO2 laser cutting will be a new technique in this industry, and this analysis will assist the manufacturing industry to choose a suitable laser system with exhaustive information of process parameters for cutting or machining of rubber, TPEs, and TPVs.

Laser Surface Treatment of SAE 4340 and 300M Steels

The 300M steel has emerged from the high strength SAE 4340 steel, which had been developed in order to obtain increased toughness and weldability in applications requiring better mechanical properties; some minor changes in the alloy elements were introduced: addition of vanadium, and raise in the silicon content. The laser surface hardening is a process in which the steel surface is heated below the melting point, in order to produce solid state phase transformations whithout changing the bulk. This work has evaluated which would be the best parameters for the laser carburizing heat treatment using a low power (50W) CO2 laser, comparing and contrasting the resulting microstructure and hardness of both steels. The following CO2 laser parameters were varied: speed, resolution and number of passes; power was kept constant. Carbon black was used as coating. After the surface laser treatment, the samples were cooled in air and the formation of a hardened layer and heat affected zone in both materials was observed. Samples were prepared for metallographic analysis, followed by optical and scanning electron microscopy observation. Layers presented a Vickers hardness value higher than the base metal and the hardened layer had a higher hardness value compared to the heat affect zone. The formation of martensite in the heat affected zone in both steels was observed, although not to the full extension, making this a multiphasic zone.

Comparative Assessment on Laryngeal Function after Radiotherapy and Laser Surgery against Early Glottic Cancer

Objectives: Comparatively assess the laryngeal function and quality of life (QOL) of the patients after laser surgery and radiotherapy against early glottic cancer. Methods: Sixty-seven patients with T1 glottic cancer treated in our institution with radiotherapy (RT, n=30) or CO2 laser surgery (LS, n=37) were incorporated in this retrospective cohort study. LSs were performed following the type II subligamental cordectomy concept. Patients in LS group were categorized into subgroups for further analyses. Twenty-seven patients had vaporization of the lesion with defocused mode, and a residual 10 patients had cancer excision with focused mode using relatively lower power (LS-EX group). GRBAS subjective voice assessment scale, maximum phonation time, and acoustic parameters were measured as vocal parameters. Voice-Related Quality of Life Measure and Voice Handicap Index were used to evaluate post-therapeutic QOL. Laryngeal videostroboscopic images were further examined to assess post-therapeutic laryngeal pliability. The mean follow-up period was 46 months. Results: Compared with their pre-therapeutic scores, worse GRBAS scores were observed at the end of the treatments in 20% and 60% of RT group and LS group respectively. Although these scores recovered 1 year after treatment, abnormal stroboscopic findings remained in 40% and 95% of RT group and LS group respectively. Interestingly, further subgroup analysis proved no significant difference of post-therapeutic vocal parameters and QOL between RT group and LS-EX group. Conclusions: Early glottic cancer could be treated with equivalent post-therapeutic laryngeal function and QOL with either radiotherapy or focused low power CO2 laser surgery.

Thinning of large-area graphene film from multilayer to bilayer with a low-power CO2 laser

Bilayer graphene has attracted a great deal of attention for many electronic and optical applications. Although large-area bilayer graphene can be synthesized by chemical vapor deposition (CVD), multilayer growth often occurs and subsequent processes are required to obtain uniform bilayer films. We report an efficient way of thinning multilayer graphene film by low-power CO2 laser irradiation in vacuum. With a laser power density of ∼102 W cm−2, pristine graphene film of 4–5 layers can be thinned to a bilayer free of defects in 30 s. Contrary to previous laser-assisted graphene thinning processes, which reduced graphene layers precisely and locally with a high power density and a small beam diameter, our approach enables high-efficiency thinning of large-area graphene film whilst using a significantly reduced power density and an increased laser beam diameter.

A low-cost rapid prototyping method for metal electrode fabrication using a CO2 laser cutter

In this note, a novel approach on the use of a low-power CO2 laser cutter is proposed to pattern thin metal electrode prototypes. Although low-power CO2 laser cutters have been used to etch and cut a wide range of materials, based on our knowledge, metal electrode patterning has not been previously explored. Using the proposed approach, metal electrodes can be patterned on the substrates that are good absorbers of CO2 wavelength. Here, polymethylmethacrylate substrates are selected and metal electrode patterning using the commercial CO2 laser cutter of VLS 3.50 Versa Laser is investigated. This approach has a wide range of applications, and two of those examples for microwave heating and antenna applications are presented.

The effects of low-frequency workpiece vibration on low-power CO2 laser cutting of PMMA: an experimental investigation

The effect of workpiece vibration on low-power CO2 laser cutting of polymethyl methacrylate (PMMA) has been investigated. 6-mm-thick PMMA sheets have been cut using a 70-W continuous wave CO2 laser moving at speeds in the range of 0.1–2.0 m/min. The workpiece was vibrated in a direction parallel to the laser cut at frequencies of 0, 12, 18 and 24 Hz. The use of workpiece vibration was shown to enhance the cutting process. At 12 Hz, the cutting speed was increased to 0.4 m/min compared to 0.2 m/min for the 0-Hz sample. However, the extent of the HAZ increased when workpiece vibration was used.

Modulation of Signal-Transducing Function of Neuronal Membrane Na+,K by Endogenous Ouabain and Low-Power Infrared Radiation Leads to Pain Relief

Effects of infrared (IR) radiation generated by a low-power Co2-laser on sensory neurons of chick embryos were investigated by organotypic culture method. Low-power IR radiation firstly results in marked neurite suppressing action, probably induced by activation of Na+,K+-ATPase signal-transducing function. A further increase in energy of radiation leads to stimulation of neurite growth. We suggest that this effect is triggered by activation of Na+,K+-ATPase pumping function. Involvement of Na+,K+-ATPase in the control of the transduction process was proved by results obtained after application of ouabain at very low concentrations. Physiological significance of low-power IR radiation and effects of ouabain at nanomolar level was investigated in behavioral experiments (formalin test). It is shown that inflammatory pain induced by injection of formalin is relieved both due to ouabain action and after IR irradiation.

Mechanism of Pain Relief by Low-Power Infrared Irradiation: ATP is an IR-Target Molecule in Nociceptive Neurons

Effects of infrared (IR) radiation generated by a low-power CO2-laser on the membrane of cultured dissociated nociceptive neurons of newborn rat spinal ganglia were investigated using the whole-cell patch-clamp method. Low-power IR radiation diminished the voltage sensitivity of activation gating machinery of slow sodium channels (Na(v)1.8). Ouabain known to block both transducer and pumping functions of Na+,K+-ATPase eliminated IR irradiation effects. The molecular mechanism of interaction of CO2-laser radiation with sensory membrane was proposed. The primary event of this interaction is the process of energy absorption by ATP molecules. The transfer of vibrational energy from Na+,K+- ATPase-bound and vibrationally excited ATP molecules to Na+,K+-ATPase activates this enzyme and converts it into a signal transducer. This effect leads to a decrease in the voltage sensitivity of Na(v)1.8 channels. The effect of IR-radiation was elucidated by the combined application of a very sensitive patch-clamp method and an optical facility with a controlled CO2-laser. As a result, the mechanism of interaction of non-thermal low-power IR radiation with the nociceptive neuron membrane is suggested.

低功率CO2激光辐照对多层石墨烯结构的影响

低功率CO₂激光辐照对多层石墨烯结构的影响

Fabrication and characterization of a polymethyl methacrylate continuous-flow PCR microfluidic chip using CO2 laser ablation

An improved microfabrication method was used to fabricate a continuous-flow PCR (polymerase chain reaction) microfluidic chip on the PMMA substrate using the low-power CO2 laser ablation technique. The use of the low-power CO2 laser and the PMMA material could reduce the cost and the time of the fabrication process, especially at the step of laboratory research because of the high flexibility of the laser fabrication technique and the low cost of PMMA. A CO2 laser output power of 4.5 W and a laser scanning velocity of 76.2 mm/s were chosen to fabricate the chip in this work. The micromachining quality could satisfy the microfluidic requirement of the PCR mixture within the microchannel. Good temperature distribution and gradient were obtained on the PMMA chip with a home-built integrated heating system. An amplification of DNA template with a 990 base pair fragment of Pseudomonas was successfully performed with this chip to characterize its availability and performance with various flow rates.

Fabrication and flow test of long-term hydrophilic fluidic chip without using any surface modification treatment

In order to effectively pump liquid in a fluidic chip, the PDMS or SU8 channels were frequently modified by surface treatments to obtain the hydrophilic surface but encountered the problem of the hydrophobic recovery. In this article, long-term highly hydrophilic fluidic chips were demonstrated using rapid fabrication of low-power CO2 laser ablation and low-temperature glass bonding with an interlayer of liquid crystal polymer (LCP). The intrinsic hydrophilic materials of glass and LCP were beneficial for self-driven flow in the long-term fluidic chip by surface-tension force with no extra fluidic pumps. The higher viscosity fluid could increase the difficulty of self-driven capability. The stability of contact angle and flow test of the chip after 2 months is similar to that at beginning. The high-viscosity human whole blood was successfully driven at an average moving velocity of about 1.89 mm/s for the beginning and at 2.04 mm/s after 2 months. Our fluidic chip simplifies the traditional complex fabrication procedure of glass chips and conquers the problem of traditional hydrophobic recovery.

Thermal Treatment of the AISI M2 High Speed Steel Promoted by a CO2 Laser Beam

The purpose of this paper is the evaluation of the use of a low power CO2 laser beam (50W) to promote the thermal treatment of AISI M2 high-speed steels and evaluate the tribological properties of the graphite coating that takes place on the steel surface after laser irradiation. In order to minimize the steel surface reflection at approximately 90% of the incident radiation wavelength (10.5 μm), an incident radiation absorber layer was applied to the steel surface sample. This coating aims to absorber the incident heat and transfer part of heat to the steel surface. As results the surface presented high hardness and a thin coating of graphite on the surface. The micro-structural changes, occurred on the steels surface, resulting from heat transfer from the absorbing layer, were evaluated through optical microscopy (MO), scanning electron microscopy (MEV), micro-hardness essays (MH), X-ray analysis (XRD), Raman spectroscopy and tribological testers on the graphite coating. MO analysis showed on the transversal section of the heated affected zone a brighter layer than the sample’s core, 30 micrometers thickness, in the surface sample a black coat 10 micrometers thickness. By MH analysis this brighter layer presented hardness approximately 30% superior than the regions without treatment, and by Raman spectroscopy it was evaluated the graphite coating. The XRD analysis on the surface sample reveals an increasing of the martensite and iron-carbide phase. The experimental results of pin-on-disk tests on the graphite coatings reveal a reduced coefficient friction as compared to the original surface.