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Optimizing Settings for Officea??Based Endoscopic CO <sub/>2</sub> Laser Surgery Using an Experimental Vocal Cord Model
摘要： Objectives/Hypothesis: To provide insight in the thermal effects of individual laser settings in target tissues to optimize flexible endoscopic CO2 laser surgery treatment. Study Design: Experimental laboratory study. Methods: Thermal effects of the CO2 laser using a fiber delivery system were visualized using the color Schlieren technique in combination with a polyacrylamide gel tissue model. Variable settings were used for emission mode, power, laser fiber distance, and laser duration, which were evaluated in every possible combination. Collateral thermal expansion and incision depth were measured. To validate the model, the results were compared to histology after CO2 laser irradiation of ex vivo human vocal cords, and the intraclass correlation coefficient was calculated. Thermal damage and incision depth were measured by a blinded pathologist. Results: Of all parameters studied, duration of laser irradiation had the greatest effect on thermal expansion. Increased distance between laser tip and target tissue resulted in significantly reduced incision depth and increased thermal expansion. Pulsed emission modes led to increased incision depths. The intraclass correlation coefficient for consistency between the model setup and the ex vivo human vocal cords was classified as “fair.” Conclusions: By using high-intensity pulsed lasers at minimal distance to the target tissue, exposure times and subsequent damage to surrounding tissue can be reduced. If an evaporation technique is used, lower power in continuous wave at a larger distance to the target tissue will lead to superficial but broader thermal effects. The model setup used in this study is a valid model to investigate laser-induced thermal effects in vocal cord tissue.
关键词： vocal cords,thermal effects,Flexible endoscopic CO2 laser
更新于2025-09-19 17:13:59
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Fractionated CO2 Laser as Therapy in Recalcitrant Lichen Sclerosus
摘要： The aim of this study was to evaluate the efficacy of the fractionated CO2 laser in treating recalcitrant lichen sclerosus (LS). The study population was 40 women diagnosed with LS who were symptomatic despite medical treatment. Patients had at least 2 or more laser sessions with a 2-month follow-up visit at the Drexel Vaginitis Center. A fractionated CO2 laser was used on affected areas at mild or standard power settings. Analyses were performed of changes in symptom rating scales, verbal reports, and physical examination findings. In the LS cohort of 40 patients, 22 women (55%) experienced symptoms that had persisted longer than 5 years before treatment. After the appropriate laser sessions, 72.5% of women described their improvement as significant or more than 66% improvement. In addition, there was a statistically significant reduction in vaginal pain, itching, dyspareunia, and dysuria. The presence of white epithelium decreased 20% after treatment. Furthermore, the mean corticosteroid use declined from 4.28 times per week to 2.04 times per week, indicating a resolution of many symptoms. The fractionated CO2 laser may be a helpful approach for managing LS that is unresponsive to traditional treatment options.
关键词： lichen sclerosus,fractionated CO2 laser,corticosteroid
更新于2025-09-19 17:13:59
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Optimization of welding parameters in laser welding of Ti6Al4V using VIKOR optimization method
摘要： Ti6Al4V alloys are widely preferred in the biomedical industries owing to its higher corrosion resistance in human body environment. Welding plays a critical role in the manufacture of complicated biomedical components. Hence, the necessity to identify suitable joining process for joining Ti6Al4V is very important. In this work, an attempt is made to study the CO2 laser welding of titanium sheets (Ti6Al4V) having dimensions of 100 (cid:1) 60 (cid:1) 3 mm. Laser welding was done based on L9 Taguchi array with welding speed (v), laser power(P), and shielding gas ?ow rate(f) as input parameters. The weld quality was analysed by measuring the depth of penetration (DOP), bead width (BW), and hardness values. Full penetration was observed only in two welding trials. The optimized parameters were identi?ed by using the VlseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR) multi-objective optimization technique. Analytic Hierarchy Process (AHP) is used for determining the weights of the relative importance of the output factors. VIKOR method identi?ed that the 7th experimental run (power = 1.3 kW, speed = 0.3 m/min, shielding gas ?ow rate = 20 L/min) as the optimized parameter for getting the weld with full depth of penetration, lesser bead width, higher microhardness values in the fusion zone (FZ) and heat affected zone (HAZ). The metallurgical characterization of the optimized weld is also dicussed with the aid of microstructures taken from Scanning Electron Microscope (SEM).
关键词： CO2 laser welding,Hardness values,Bead geometry,VIKOR multi-objective optimization technique,Ti6Al4V
更新于2025-09-19 17:13:59
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Testing of diffractive optical element as part of specific CO <sub/>2</sub> laser equipment for metallic materials modification
摘要： Testing of a reflective diffractive optical element (DOE) as part of specific CO2 laser equipment Oerlikon OPL 2000 for metallic materials modification was performed. The power density distribution in a plane located behind the DOE focal plane has been measured. It was found that DOEs make it possible to form a predetermined beam power density profile and to perform the transformation of laser energy, chosen by calculation previously. The use of these optical elements in the laser material treatment reveals new possibilities for controlling properties and operational characteristics of processed components. Additional redistribution of the beam power to edges of the laser spot is achieved by increasing the proportion of energy reflected by DOE peripheral zones, for example, by increasing the aperture of the focusable beam. It is proposed using a telescopic system of two lenses to change the aperture of the laser beam focusable by the DOE.
关键词： metallic materials modification,diffractive optical element,beam power density profile,CO2 laser
更新于2025-09-19 17:13:59
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Comparison of Clinical Outcomes of CO2 Laser-Assisted Blepharoplasty Using Two Different Methods
摘要： Numerous methods have been developed for blepharoplasty, including carbon dioxide (CO2) laser-assisted blepharoplasty. Although the superiority of CO2 laser compared with the scalpel for blepharoplasty has been proposed, to the best of our knowledge, no study has compared the clinical outcomes of blepharoplasty with the CO2 laser alone versus the combined use of a scalpel and CO2 laser. In the present randomized clinical trial, 21 healthy patients underwent bilateral upper eyelid blepharoplasty. For each patient, an initial skin incision was made using the CO2 laser (setting, continuous emission; ultrapulse mode; 3 W of power) on 1 side and a scalpel on the other side. The remaining blepharoplasty steps were conducted using the CO2 laser (setting, continuous emission; 9 W of power) in both groups. The patients were evaluated on postoperative days 1, 3, 7, 14, and 30 using the postoperative repair criteria, including edema and ecchymosis. The Manchester scar scale was used to evaluate the results at 60 days after surgery. Our comparison of the 2 methods showed no signi?cant differences at 1 month after surgery using the evaluation criteria. The scar index was not signi?cantly different after 60 days, despite lower scores in the scalpel group. In upper eyelid blepharoplasty, making an initial incision with a scalpel, followed by use of a laser provides advantages similar to those found by performing the entire procedure with a CO2 laser alone.
关键词： Scalpel,CO2 Laser-Assisted Blepharoplasty,Clinical Outcomes,Upper Eyelid Blepharoplasty
更新于2025-09-19 17:13:59
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Comparative Investigation by Infrared Spectroscopy of the Conformational Metamorphosis of Polyvinylidene Fluoride Under the Action of an Infrared Laser and of γ-Irradiation
摘要： The irradiation of a poly(vinylidene ?uoride) (PVDF) plate with γ-rays up to 100 kGy leads to the breaking of the chain and the formation of unsaturated bonds but practically does not have any e?ect on the conformation composition of PVDF macromolecules. The main conformer, as in native PVDF, is the β form. Irradiation with an IR laser leads to a noticeable carbonization of PVDF macromolecules and is accompanied by a structural transition of polymer macromolecules from the β conformer to the α conformer. In the IR spectrum of the powdered product from laser ablation of PVDF, in addition to the absorption bands of the ablation crater, absorption bands from the parent PVDF are still present.
关键词： poly(vinylidene ?uoride),CO2 laser ablation,IR spectra,γ-irradiation
更新于2025-09-19 17:13:59
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CO2 Laser Cutting Performance on Ultra High Strength Steel (UHSS)
摘要： Evolution of a new breed steel, Ultra High Strength Steel (UHSS), has been adapted by the automotive industry after being used for heavy trucks. Higher tensile strength and improved mechanical properties of UHSS are the main reason for its selection particularly in Body In White (BIW) construction at critical chassis area. Laser cutting process is noted as the final trimming method for this harden material as die pressing resulted as an ineffective process. UHSS cutting performance using CO2 laser with variation on laser power, cutting speed, assist gas type and assist gas pressure was determined to identify the effect of these parameters on the cutting quality. Cutting quality assessment was carried out according to EN ISO 9013 standard where kerf width, perpendicularity and microhardness were evaluated based on parameters set at 1.7 mm thickness of 22MnB5 UHSS boron steel. The quality of these cuttings was evaluated as the results show that thermal exposure dependent on energy density and gas type reflect the outcome where higher thermal exposure introduced bigger kerf with better perpendicularity. It was also found that isothermal effects such as Heat Affected Zone (HAZ) and martensitic transformation were also clearly visible since nitrogen produced a better cutting quality and material integrity consumption at the cutting edge.
关键词： Perpendicularity,22MnB5,Microhardness,CO2 laser,Kerf width
更新于2025-09-19 17:13:59
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Synthesis and Characterization of Laser Induced Graphene (LIG) and laser Reduced Graphene Oxide (lrGO) by using a pulsed CO <sub/>2</sub> laser
摘要： We detail a method to produce graphite materials with a three-dimensional, flexible and porous structure obtained from the exposure to CO2 laser radiation. One of them is Laser Induced Graphene (LIG) grown from an insulating polyimide as raw material, and the other is laser reduced graphene oxide (lrGO), obtained from a graphene oxide (GO) thin film. For both materials, we describe their morphology, crystalline structure and electrical characterizations. These materials have important applications in organic electronics technology.
关键词： LIG,laser reduced graphene oxide,Laser Induced Graphene,lrGO,flexible electronics,CO2 laser
更新于2025-09-16 10:30:52
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Enhanced topical cutaneous delivery of indocyanine green after various pretreatment regimens: comparison of fractional CO2 laser, fractional Er:YAG laser, microneedling, and radiofrequency
摘要： Different devices have been used to enhance topical drug delivery. Aim of this study was to compare the efficacy of different skin pretreatment regimens in topical drug delivery. In six ex vivo human abdominal skin samples, test regions were pretreated with fractional CO2 and Er:YAG laser (both 70 and 300 μm ablation depth, density of 5%), microneedling (500 μm needle length), fractional radiofrequency (ablation depth of ± 80–90 μm), and no pretreatment. The fluorescent agent indocyanine green (ICG) was applied. After 3 h, fluorescence intensity was measured at several depths using fluorescence photography. Significantly higher surface fluorescence intensities were found for pretreatment with fractional Er:YAG and CO2 laser and for microneedling vs. no pretreatment (p < 0.05), but not for radiofrequency vs. no pretreatment (p = 0.173). Fluorescence intensity was highest for the Er:YAG laser with 300 μm ablation depth (mean 38.89 arbitrary units; AU), followed by microneedling (33.02 AU) and CO2 laser with 300 μm ablation depth (26.25 AU). Pretreatment with both lasers with 300 μm ablation depth gave higher fluorescence intensity than with 70 μm ablation depth (Er:YAG laser, 21.65; CO2 laser, 18.50 AU). Mean fluorescence intensity for radiofrequency was 15.27 AU. Results were comparable at 200 and 400 μm depth in the skin. Pretreatment of the skin with fractional CO2 laser, fractional Er:YAG laser, and microneedling is effective for topical ICG delivery, while fractional radiofrequency is not. Deeper laser ablation results in improved ICG delivery. These findings may be relevant for the delivery of other drugs with comparable molecular properties.
关键词： Radiofrequency,Fractional laser,Er:YAG laser,Microneedling,Drug delivery,CO2 laser
更新于2025-09-16 10:30:52
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AIP Conference Proceedings [AIP Publishing PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS WITH HIERARCHICAL STRUCTURE FOR NEW TECHNOLOGIES AND RELIABLE STRUCTURES 2019 - Tomsk, Russia (1–5 October 2019)] PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS WITH HIERARCHICAL STRUCTURE FOR NEW TECHNOLOGIES AND RELIABLE STRUCTURES 2019 - Cutting of aluminum alloys with a Q-switched repetitively pulsed CO2 laser under conditions of intense material evaporation
摘要： The results of an experimental study of laser cutting of aluminum-lithium alloys using a repetitively pulsed CO2 laser with Q-switching under conditions of intense material evaporation are presented. The dependence of cut quality on the assisted gas pressure is determined. It is shown that a high-quality cut with a sheet thickness of 1.5 mm can be obtained at a gas pressure of 0.5–0.6 bar, which is significantly less compared to cutting with a continuous laser power. This makes it possible to reduce the assisted gas consumption. The dependence of cut surface roughness on the pulse repetition rate is measured.
关键词： laser cutting,aluminum-lithium alloys,material evaporation,Q-switched CO2 laser,cut quality,pulse repetition rate,gas pressure
更新于2025-09-16 10:30:52