CO2 Laser Wavelength Research Articles

CO2 laser enhanced rapid IRMPD spectroscopy for glycan analysis

Infrared Multiple Photon Dissociation (IRMPD) spectroscopy, a combination of Mass Spectrometry (MS) and InfraRed Ion Spectroscopy offers unprecedented performance for molecular structure analysis by adding a spectroscopic dimension to MS workflows. The potential of such approach is particularly relevant for glycomics because carbohydrates of a given mass exist in a large variety of isomers that cannot be resolved by MS alone. We recently reported the development of a rapid and automated IRMPD setup that allowed the acquisition of IR spectra within a few seconds. This rapid IRMPD showed excellent performances in the case of protonated species but also severe limitations when applied to other types of ions. Here we combine a fixed wavelength CO2 laser with a tuneable high repetition rate IR laser to enhance the laser-induced fragmentation. We have applied this method to typical cases encountered in glycan analysis: sodiated species obtained with glycans extracted from natural biological samples, identification of isomers of lithiated hexoses and analysis of acidic negatively charged monosaccharides. This opens new avenues in the development of IRMPD as an analytical tool for glycans.

Bowtie Nanoantenna Coupled Metal-Oxide-Silicon (p-Doped) Diode for 28.3 THz IR Rectification.

Low-temperature waste heat in the infrared (IR) wavelength region offers an opportunity to harvest power from waste energy and requires further investigation in order to find efficient conversion techniques. Although grating-coupled metal-oxide-semiconductor (MOS) diode devices offer efficient conversion from low and moderate-temperature thermal sources, the integration of such diodes with a nanoantenna structure has yet to be explored. We propose a bowtie nanoantenna coupled with a p-doped MOS diode for IR to direct current (DC) conversion without any bias voltage at 28.3 THz. The nanoantenna was designed and optimized to provide maximum field enhancement in a 4 nm-thick oxide layer at the resonant frequency. The device was fabricated following the complementary MOS (CMOS) fabrication process and measured in a custom DC and optical characterization setup using a 10.6 μm wavelength CO2 laser. The results reveal two different types of devices with linear and nonlinear I-V curves having kΩ and MΩ zero-bias resistance, respectively. The linear device generates a micron-level open-circuit voltage (Voc) with clear polarization dependence from the laser input, but the nonlinear case suffers from a weak noise-like signal. Finally, we analyze two types of devices using thermoelectric and tunneling effects and discuss the future direction of nanoantenna-integrated MOS devices for efficient IR harvesters.

Theoretical and experimental investigations for geometrical error during hemispherical cavity machining on CO2 laser

CO2 laser material processing has become popular due to its unique advantages such as high productivity, ease of automation, non-contact processing, greater material utilization, and minimum heat-affected zone. Polymethylmethacrylate (PMMA) is found to be one of the most suitable thermoplastics for CO2 laser machining due to its higher melting point and higher absorptivity at the CO2 laser wavelength. The scope of the present work deals with geometrical error analysis during machining of the three-dimensional spherical cavity with the help of a 2D setup of the laser. The influence of process parameters like power, cutting speed, and the number of passes of laser probe on cusp height is examined. The cusp height is measured after machining equal and unequal step size on PMMA. The experiments were performed for profile controlled approach for equal step size and accuracy approach for unequal step size. An algorithm is proposed for predicting unequal step diameter with a constant value of cusp height. It was observed that higher power, lower speed, and more number of passes of laser probe leads to minimum cusp height. Hence, the proposed algorithm for predicting unequal step diameter for a constant cusp height leads to a reduction in staircase effect, thereby, producing a smoother curve as compared to the profile controlled (equal step diameter) approach.

Tuning the Laser‐Induced Processing of 3D Porous Graphenic Nanostructures by Boron‐Doped Diamond Particles for Flexible Microsupercapacitors

AbstractCarbon (sp3)‐on‐carbon (sp2) materials have the potential to revolutionize fields such as energy storage and microelectronics. However, the rational engineering and printing of carbon‐on‐carbon materials on flexible substrates remains a challenge in wearable electronics technology. This study demonstrates the scalable fabrication of flexible laser‐induced graphene (LIG)‐boron doped diamond nanowall (BDNW) hybrid nanostructures for microsupercapacitors. Direct laser writing on polyimide film is tuned by the presence of BDNW powder where an appreciable absorbance of the BDNWs at the CO2 laser wavelength enhances the local film temperature. The thermal shock due to laser irradiation produces graphitized and amorphous carbon at the diamond grain boundaries which increases the thermal and charge transfer capacity between the LIG–diamond interfaces. The samples are further treated with O2 plasma to tune the wettability or to improve the microsupercapacitor device performance. The outstanding electrical characteristics of graphene, exceptional electrochemical stability of diamond, and essential contributions of oxygen‐containing groups result in a remarkable charge storage capacity (18 mF cm−2 @ 10 mV s−1) and cyclic stability (98% retention after 10 000 cycles) outperforming most state‐of‐the‐art LIG‐based supercapacitors. Furthermore, despite extreme mechanical stress, these microsupercapacitors maintain their outstanding electrochemical properties, thus holding promise for high‐power, flexible/wearable electronics.

Three-dimensional transient simulation of CO2 laser tissue vaporization and experimental evaluation with a hydrogel phantom

A quantitative analysis method of CO2 laser treatments promotes laser treatment performance and rapid clinical application of novel treatment devices. The in silico clinical trial approach, which is based on computational simulation of light-tissue interactions using the mathematical model, can provide quantitative data. Although several simulation methods of laser tissue vaporization with CO2 laser treatments have been proposed, validations of the CO2 laser wavelength have been insufficient. In this study, we demonstrated a tissue vaporization simulation using a CO2 laser and performed the experimental validation using a hydrogel phantom with constant physical parameters to evaluate the simulation accuracy of the vaporization process. The laser tissue vaporization simulation consists of the calculation of light transport, photothermal conversion, thermal diffusion, and phase change in the tissue. The vaporization width, depth, and area with CO2 laser irradiation to a tissue model were simulated. The simulated results differed from the actual vaporization width and depth by approximately 20% and 30%, respectively, because of the solubilization of the hydrogel phantom. Alternatively, the simulation vaporization area for all light irradiation parameters, which is related to the vaporization amount, agreed well with the actual vaporization values. These results suggest that the computational simulation can be used to evaluate the amount of tissue vaporization in the safety and effectiveness analysis of CO2 laser treatments.

Highly sensitive Laser Photo-Acoustic SF6 Gas Analyzer with 10 decades dynamic range of concentration measurement

A highly sensitive Laser Photo-Acoustic (PA) SF6 Gas Analyzer with dynamic range of ∼10 decades (∼0.1 ppb–100% SF6) has been developed and tested. Gas analyzer is built on the base of RF-excited waveguide CO2 laser, resonant differential photo-acoustic detector (PAD), and sealed-off SF6-gas-filled Ref-cell. The resonant frequency of differential PAD is measured automatically in real time (∼1750–1780 Hz, error ± 0.1 Hz). While measuring SF6 concentration (up to 1000 ppm), normalization of PAD’s absorption signals according by Ref-cell absorption signals significantly reduce the error in PA gas analyzer readings caused by spontaneous tuning of waveguide CO2 laser wavelength near ∼10.6 μm. PA gas analyzer’s background readings was ∼0.1 ppb SF6, the standard dispersion of background signal was ∼10 ppt SF6. Minimum average power of waveguide CO2 laser radiation should be no less than ∼150 mW. Dependence of speed of sound vs gas mixture composition was used to measure SF6 concentration in 0.1–100% range. Resonant frequency of differential PAD varied from ∼1780 Hz (pure N2) to ∼690 Hz (pure SF6), which, after appropriate calibration, makes it possible to measure SF6 concentration up to 100%.

Enamel erosion prevention and mechanism: effect of 10.6-μm wavelength CO2 laser low power density irradiation studied by X-ray fluorescence and infrared spectroscopy and scanning electron microscopy

This study assessed the effects of carbon dioxide (CO2) laser (λ = 10.6 μm, 5 W, 70 J/cm2) irradiation alone and after treatment with neutral fluoride gel on enamel and their efficacy in preventing enamel erosion compared to untreated and fluoride gel-treated enamel. Enamel surfaces of the bovine incisor (n = 7/group) were treated with artificial saliva (S, negative control), neutral fluoride (NF, positive control), CO2 laser irradiation (L), and NF + laser (NF + L). Samples were acid demineralized (soft drink, pH ~ 3.2, 10 min), remineralized (saliva, 37 °C, 1 h), and analyzed using micro-energy-dispersive X-ray fluorescence spectrometry (μ-EDXRF), attenuated total reflectance–Fourier-transform infrared (ATR-FTIR) spectroscopy, and scanning electron microscopy (SEM). Results suggest that NF gives the best protection against erosion, followed by NF + L and L. μ- EDXRF showed that changes due to laser treatment in L and NF + L were uneven. SEM images showed morphological changes in L and NF + L such as craters, fissures, and roughness in some regions, again indicating the unevenness of laser-induced enamel changes. ATR-FTIR mean spectra intensity levels and principal component analysis also indicate higher efficacy of fluoride over laser treatments and unevenness of laser treatments. Overall, it can be concluded that CO2 laser parameters need to be further investigated to promote adequate protection with minimum surface changes.

Fissure caries inhibition with a CO2 9.3-μm short-pulsed laser-a randomized, single-blind, split-mouth controlled, 1-year clinical trial.

The objective of this randomized, single-blind, split-mouth controlled, clinical trial was to evaluate whether the use of a short-pulsed 9.3-μm CO2 laser increases the caries resistance of occlusal pit and fissures in addition to fluoride therapy over 12months. A total of 60 participants, average age 13.1years, were enrolled. At baseline, second molars were randomized into test and control, and assessed by ICDAS, SOPROLIFE, and DIAGNOdent. An independent investigator irradiated test molars with a CO2 laser (wavelength 9.3μm, pulse duration 4μs, pulse repetition rate 43Hz, beam diameter 250μm, average fluence 3.9J/cm2, 20 laser pulses per spot). Test molars received laser and fluoride treatment, control teeth fluoride alone. Fluoride varnish was applied at baseline and at 6months. After 6 and 12months, teeth were again assessed. A total of 57 participants completed the 6-month and 51 the 12-month recall. Laser-treated surfaces showed very slight ICDAS improvements over time with ICDAS change - 1 in 11% and 8%, no changes (ICDAS change 0) in 68% and 67%, and slightly worsened (ICDAS change 1) in 19% and 24% at 6- and 12-month recalls, respectively, and worsened by two scores in 2% at both recall time points. Control teeth showed significantly higher ICDAS increases, with 47% and 25% showing ICDAS change 0, ICDAS change 1 in 49% and 55%, and ICDAS change 2 in 4% and 20% at 6- and 12-month recalls, respectively. Differences in ICDAS changes between the groups were statistically significant (P = 0.0002 and P < 0.0001; Wilcoxon's signed-rank test, exact). A total of 22% of the participants developed ICDAS 3 scores on the control teeth. Microsecond short-pulsed 9.3-μm CO2 laser irradiation markedly inhibits caries progression in pits and fissures in comparison with fluoride varnish alone. The 9.3-μm CO2 laser irradiation of pits and fissures enhances caries resistance. ClinicalTrials.gov identifier: NCT02357979.

Experimental Investigation of Industrial Laser Cutting: The Effect of the Material Selection and the Process Parameters on the Kerf Quality

Laser beam cutting is a non-contact, production-flexible and highly productive technique that allows accurate profiling of a wide range of sheet materials. To these and further benefits, laser machining is increasingly being adopted by industry. This paper investigates the effect of material type, workpiece thickness, cutting speed and assistant gas pressure on cut quality for industrial-relevant applications using a CO2 laser. AlMg3 aluminum alloy, St37-2 low-carbon steel and AISI 304 stainless steel were selected to represent the most established materials in many industrial fields and gain insight into different processes (i.e., inert-assisted fusion cutting and oxygen cutting) and absorption behaviors with respect to CO2 laser wavelength. The aim was to enhance the understanding of the mechanisms through which laser cutting parameters and workpiece parameters interact in order to identify general criteria and well-optimized process parameters which guarantee the kerf quality. The quality of laser cut was analyzed in its basic terms: kerf geometry, surface roughness and cut edge quality. The experiments were performed by using a systematic experimental design approach based on Design of Experiments, and the results were validated via Analysis of Variance. Quality assessment was presented and discussed. The visual inspection of cut sections confirms good overall quality and limited presence of laser cut imperfections. The experimental investigation demonstrates that the different materials can be successfully processed within a wide range of the tested values. In addition, optimum cutting conditions which satisfy the straight requirement of the quality standard adopted are identified for each material. This study involves an analysis of both phenomenological and practical issues.

The effect of CO2 9.3μm short-pulsed laser irradiation in enamel erosion reduction with and without fluoride applications-a randomized, controlled in vitro study.

The aim of this in vitro study was to evaluate the protective effect of short-pulsed CO2 9.3μm laser irradiation against erosion in human enamel without and combined with TiF4 and AmF/NaF/SnCl2 applications, respectively, as well as compared to the protective effect of these fluoride treatments alone. After polishing, ninety enamel samples (3 × 3mm) were used for 9 different treatment groups: 4% TiF4 gel (pH1.5, 24,533ppmF-); AmF/NaF/SnCl2 rinse (pH4.5; 500ppmF-, 800ppm Sn2); CO2 laser (average power 0.58W); CO2 laser (0.58W) + TiF4; CO2 laser (0.58W) + AmF/NaF/SnCl2; CO2 laser (0.69W); CO2 laser (0.69W) + TiF4; CO2 laser (0.69W) + AmF/NaF/SnCl2; negative control (deionized water). TiF4 gel was brushed on only once before the first erosive cycling, while samples treated with AmF/NaF/SnCl2 were daily immersed in 5ml of the solution before cycling. Laser treatment occurred with a CO2 laser (wavelength 9.3μm, pulse repetition rate 100Hz, pulse duration 14.6μs/18μs, average power 0.58W/0.69W, fluence 1.9J/cm2/2.2J/cm2, beam diameter 0.63mm, irradiation time 10s, air cooling). TiF4 was applied only once, while AmF/NaF/SnCl2 was applied once daily before the erosive challenge. Surface loss (in μm) was measured with optical profilometry immediately after treatment, and after 5 and 10days of erosive cycling (0.5% citric acid, pH2.3, 6 × 2min/day). Additionally, scanning electron microscopy investigations were performed. All application measures resulted in loss of surface height immediately after treatment. After 5days, significantly reduced surface loss was observed after applying laser irradiation (both power settings) followed by applications of TiF4 or AmF/NaF/SnCl2 solution (p < 0.05; 2-way ANOVA and Tukey test) compared to fluoride application alone. After 10days, compared to after 5days, a reduced tissue loss was observed in all groups treated with AmF/NaF/SnCl2 solution. This tissue gain occurred with the AmF/NaF/SnCl2 application alone and was significantly higher when the application was combined with the laser use (p < 0.05). Short-pulsed CO2 9.3μm laser irradiation followed by additional application of AmF/NaF/SnCl2 solution significantly reduces the progression of dental enamel erosion in vitro.

Experimental and statistical study on kerf taper angle during CO2 laser cutting of thermoplastic material

CO2 laser machining is an advanced material processing technology, gaining more popularity due to its low cost and rapidity as well as good cutting quality depending on the material and its properties. Polymethylmethacrylate (PMMA) is found to be one of the most suitable thermoplastics for CO2 laser machining due to its higher melting point and higher absorptivity at the CO2 laser wavelength. The kerf taper angle is one of the most important quality characteristics because it is one of the measures for the geometrical accuracy of the machined cavities. The present work deals with the CO2 laser (0–25 W) cutting of 8 mm thick PMMA material. The influence of process parameters like power, speed, and a number of passes of the laser probe is examined on the kerf taper angle. The regression analysis has been done to develop a model that studies the effect of process parameters on the kerf taper angle which is one of the important cutting quality characteristics. Experiments were carried out using the full factorial methodology, and the cylindrical blind cavities were machined for different combinations of parameters. It is found that power, speed, and a number of passes have a significant effect on the kerf taper angle. Higher laser power, lower speed, and higher number of passes of laser probe result in low kerf taper. The statistical model developed can be used for the selection of process parameters for process control.

Zero bias emission current in laser heated emissive probe and proper choice of probe-tip material

Emissive probes are considered as one of the best diagnostic tools for the direct measurement of plasma potential in low temperature plasma systems. Laser-heated emissive probes (LHEPs), due to their higher lifetime, are becoming more popular than their current-heated conventional counterparts. Graphite due to its higher absorption coefficient at CO2 laser wavelength and LaB6 due to its lower work function are commonly used as the probe materials for laser heated probes. Experiments with a probe-tip made of a graphite material have revealed that the emission processes other than thermionic emission also occur on heating the material with the laser, which can affect the plasma potential measurements and change the I-V characteristics of the LHEP. This additional emission due to the laser irradiation on the graphite-tip explains the measurements of lower values of plasma potentials and also describes the observation of an increase in electron saturation current with the increase in thermionic emission current due to heating. The possible mechanisms of this negatively charged-emission other than the thermionic emission from the graphite-tip have been thoroughly characterized in the absence of plasma. This extra emission is not observed in the probe-tip made up of LaB6, and a good comparison of I-V characteristics could be established with a conventional filament emissive probe in the case of LaB6.

Use of carbon dioxide lasers in dentistry

This paper aims to perform a descriptive analysis by reviewing publications concerned with the production of carbon dioxide (CO2) lasers and their technological advancement, optical properties, and parameters in relation to clinical applications in dentistry. This review was based on the literature search in Scopus, Google Scholar, and PubMed in English. The last search was made in December 2017 and there was no publication-year limit. : The 10,600-nm CO2 laser is a readily available dental laser on the market. It enables performance of a bloodless surgical procedure and reduces post-operative discomfort in soft tissue dental surgery. Due to the advancement of technology, CO2 lasers with short pulse duration and high peak power are available. This new-parameter CO2 laser causes less collateral thermal damage to soft tissue than conventional lasers with continuous wave mode. Recently, a 9,300-nm wavelength CO2 laser has been introduced for clinical use in dental hard tissue removal. These developments make CO2 lasers fitting for dental hard tissue preparation. The 10,600-nm CO2 laser is widely accepted for soft tissue surgery applications. Although CO2 lasers have been studied extensively in caries prevention, they have not been applied in clinical practice. The optical properties of 9,300-nm and 9,600-nm CO2 wavelengths are suitable for dental hard tissue treatment. Technological advancements in software and laser parameters will aid in new clinical application and technique development. CO2 lasers as hard tissue lasers will become more popular and more widely accessible to researchers and clinicians.

The Effects of CO2 Laser Irradiation on Color and Major Chemical Component Changes in Hardwoods

The influence of laser radiation was evaluated relative to the color and major chemical component changes of three hardwood species. The surfaces of maple (Acer pseudoplatanus L.), beech (Fagus sylvatica L.), and lime (i.e. linden, Tilia vulgaris) wood were exposed to radiation from a CO2 laser (wavelength = 10.6 µm, output power = 45 W). It was observed that increased doses of irradiation resulted in a decrease in the lightness (L*), increase in the total color difference, and a drop in the total polysaccharide content. Compared with the non-irradiated specimens, the ΔL* values at the highest irradiation doses were −56 (maple), −46.8 (beech), and −50.5 (lime). The trends observed in the FTIR spectra also showed there was a relationship between the breaking of C=O and C=C bonds in important functional groups in the lignin, hemicellulose, and carbohydrates. A highly linear correlation (R2 from 0.902 to 0.987) was observed between the increase in the ΔL* and decrease in the hemicellulose content, which degrades faster than other basic wood components. Such a phenomenon may have been related to the formation of new chromophore structures, which caused the color changes in the wood.

Formation of surface nanolayers in chalcogenide crystals using coherent laser beams

We have shown a possibility to form laser modified surface nanolayers with thickness up to 60 nm in some ternary chalcogenide crystals (Ag3AsS3, Ag3SbS3, Tl3SbS3) The laser treatment was performed by two coherent laser beams split in a space. As the inducing lasers we have applied continuous wave (cw) HeCd laser at wavelength 441 nm and doubled frequency cw Nd: YAG laser at 532 nm. The spectral energies of these lasers were higher with respect to the energy gaps of the studied crystals. The optical anisotropy was appeared and defected by monitoring of birefringence at probing wavelength of cw HeNe laser at λ = 3390 nm. The changes of the laser stimulated near the surface layer morphology was monitored by TEM and AFM methods as well as by the reflected optical second harmonic generation at fundamental wavelength of microsecond CO2 laser generating at wavelength 10600 nm. This technique may open a new approach for the formation of the near the surface nanolayers in chalcogenides using external cw laser illumination.

A Case Report of Multifocal Epithelial Hyperplasia (Heck's Disease) Treated with CO2 Laser

Focal epithelial hyperplasia or Heck’s disease is a rare benign lesion of oral mucosa caused by human papilloma virus especially subtypes 13 and 32. The disease is predominantly found in children and adolescents with indigenous heritage. This paper reports a unique case of Heck's disease in an 11-year-old Iranian girl with multiple, bilateral and elevated lesions on the buccal and labial mucosa. The lesions had persisted for a year. The disease was diagnosed as focal epithelial hyperplasia through the clinical examination. Considering esthetic and functional problems, CO2 laser (Wavelength: 10600 nm) surgery was determined as a suitable choice of treatment. The patient was followed up over 1 year with no signs of lesion recurrence.

Reflectivity modulator based on GaSb/GaAs heterostructure

A structure of gallium antimonide (GaSb) and gallium arsenide (GaAs) wafers is built to modulate light reflectivity at CO2 laser wavelength. A quantum well composed of GaSb/GaAs heterojunction with highly doped GaAs up to 3×1018 cm-3 is inserted inside a layer structure. A grating of periodic structure of GaAs and gold layer is added just below the substrate. Gsolver software is used to determine the reflectivity of incident light with the existence of free carriers. A voltage is applied to the doped layer to deplete the free electrons and the reflectivity is determined again. The significant difference in reflectivity between the two cases can be used to build a light reflectivity modulator device.

Realization of compatible stealth material for infrared, laser and radar based on one-dimensional doping-structure photonic crystals

To inhibit the radiant infrared energy between 8 and 14μm, which is the infrared atmospheric window, and decrease the echo power of detecting laser and radar, to achieve compatible stealth, a doping structural one-dimensional photonic crystal (1-D PC) with Ge, ZnSe and Si was fabricated; and then combine it with radar absorbing material (RAM) to make a compound. After that, the reflection spectra of this compound was tested, and the result shows a high average reflectance (89.5%) in 8–14μm waveband, and a reflective valley (39.8%) in the wavelength of 10.6μm, which is the wavelength of CO2 laser; and the reflectance in radar band shows that at high frequency, especially between 7.8 and 18GHz, the radar power is strongly absorbed by this material and the reflected energy attenuate over 10dB within the range from 11.1GHz to 18.3GHz, even 24.5dB to the most in the frequency of 14.6GHz.

Development and research of a laser photo-acoustic SF6 gas analyzer

An analysis of various optical schemes for the development of a laser SF6 gas analyzer based on a CO2 laser operating in free-running mode and a resonant photo-acoustic detector (PAD) is presented. The use of a sealed gas-filled cell to normalize PAD signals on the absorbed power in the cell is suggested. Compensation for the influence of the tuning of the CO2 laser wavelength near 10.6 μm on measured SF6 concentration is possible. The results of experimental studies of a laser photo-acoustic SF6 gas analyzer at various concentrations, including in the air flow, are presented. It is shown experimentally that the relative measurement error of the SF6 concentration due to the instability of the laser radiation wavelength does not exceed 5% in the range from ~80 ppb to 40 ppm. The limit of the sensitivity of the developed gas analyzer was ~1 ppb SF6.

Frequency tunable CO laser operating on the highest vibrational transition with wavelength of 8.7 μm.

A carbon monoxide laser emitting on the highest ever observed vibrational transition with a wavelength of 8.7 μm was for the first time launched. An influence of gas mixture content on the CO laser spectrum and factors limiting the longest CO laser wavelength are discussed.