Influence of secondary treatment with CO_2 laser irradiation for mitigation site on fused silica surface

The ablation debris and raised rim, as well as residual stress and deep crater will be formed during the mitigation of damage site with a CO2 laser irradiation on fused silica surface, which greatly affects the laser damage resistance of optics. In this study, the experimental study combined with numerical simulation is utilized to investigate the effect of the secondary treatment on a mitigated site by CO2laser irradiation. The results indicate that the ablation debris and the raised rim can be completely eliminated and the depth of crater can be reduced. Notable results show that the residual stress of the mitigation site after treatment will reduce two-thirds of the original stress. Finally, the elimination and the controlling mechanism of secondary treatment on the debris and raised rim, as well as the reasons for changing the profile and stress are analyzed. The results can provide a reference for the optimization treatment of mitigation sites by CO2laser secondary treatment.

STUDY ON Na_2O-GeO_2-SiO_2-PbO GLASSES USED AS THE CLADDING MATERIALS OF HOLLOW WAVEGUIDES FOR TRANSMITTING CO_2 LASER

In this paper a new kind of mid - infrared fiber material is reported. The reflective coefficients (R) of glasses in the system Na2O - ZnO - GeO2-SiO2-PbO have been measured-the refractive index becomes less than unity at 1180 - 900cm-1 range because of the existence of anomalous dispersion. The optical losses of hollow waveguides were calculated,the predicted losses at 940cm-1are 0. 65 and 0. 081B/ m as the inner diameter of fiber is 0. 5 and 1. 0mm respectively. The glasses can be used as the cladding materials of hol-low waveguides for transmitting CO2 laser from the measurements of characteristic temperatures, coefficient of expansion and chemical durability.

Accurate method for determining vibration temperatures, and gain limitation in pulse RF-discharge CO_2 laser

An accurate method of determining gain coefficients of pulse RF-discharge CO2 laser is developed, which involves the use of both the regular 00o1 and 00o2 laser transitions as probes of CO2 laser. The results indicate that the majority of transitions in discharge have anomalous gain coefficients under RF-discharge condition. This fact has not been generally recognized and the neglect of overlapping transitions can lead to errors in determining rotational temperature.

METHOD AND INSTRUMENT OF CIRCULAR CO_2 LASER MICROVASCULAR ANASTOMOSIS

ＭＥＴＨＯＤＡＮＤＩＮＳＴＲＵＭＥＮＴＯＦＣＩＲＣＵＬＡＲＣＯ＿２ＬＡＳＥＲＭＩＣＲＯＶＡＳＣＵＬＡＲＡＮＡＳＴＯＭＯＳＩＳＭＥＴＨＯＤＡＮＤＩＮＳＴＲＵＭＥＮＴＯＦＣＩＲＣＵＬＡＲＣＯ＿２ＬＡＳＥＲＭＩＣＲＯＶＡＳＣＵＬＡＲＡＮＡＳＴＯＭＯＳＩＳＹ...

Prediction and Analysis of Surface Quality of Northeast China Ash Wood during Water-Jet Assisted CO_(2) Laser Cutting

As a natural and environmentally friendly renewable material,Northeast China ash wood(NCAW)(Fraxinus mandshurica Rupr.)was cut by water-jet assisted CO_(2) laser(WACL),the surface quality was evaluated by surface roughness of cut section.The surface roughness was measured by three-dimensional(3D)profilometry.Furthermore,the micromorphology of machined surface was observed by scanning electronic microscopy(SEM).Carbon content changes of machined surface were measured by energy dispersive spectrometer(EDS).A relationship between surface roughness and cutting parameters was established using response surface methodology(RSM).It is concluded that the cutting speed,laser power and water pressure played an important role in surface roughness of cut section.The surface roughness increased as an increase in laser power.It decreased caused by increasing of cutting speed and water pressure.Measurements revealed that the surface quality of NCAW part was improved using the optimized combination of cutting parameters.The established quadratic mathematical model of a good prediction is helpful for matching suitable cutting parameters to obtain expected surface quality.

Pure germanium dioxide hollow-core fiber for transmitting CO_2 laser

A method of fabricating pure germanium dioxide hollow-core fibers has been introduced for the first time. The output power of the fabricated fiber can come to 18 W, with the transmission loss of 1.23 dB/m at 10.6 μm. The mechanism of transmitting CO2 laser by the fiber is analyzed, the transmitting loss is further discussed and its application fields are envisaged.

Cutting Experiment of Fraxinus mandshurica UsingWaterjet-Assisted CO_(2)Laser

High-quality wood products and valuable wood crafts receive everyone’s favor with the rapid development of the economy.In order to improve the cutting surface quality of wood forming parts,the cutting experiment of renewable Fraxinus mandshurica was conducted by waterjet-assisted CO_(2)laser(WACL)technology.A quadratic mathematical model for describing the relationship between surface roughness changes and cutting parameters was established.The effects of cutting speed,flow pressure and laser power on the kerf surface roughness of Fraxinus mandshurica when cutting transversally were discussed by response surface method.The experimental results showed that kerf surface roughness decreased under a lower laser power,higher cutting speed and higher flow pressure.When the cutting speed was 30 mm/s,flow pressure was 1.58 MPa and laser power was 45 W,the actual surface roughness of the optimized Fraxinus mandshurica was 2.41μm,and it was in accord with the theoretically predicted surface roughness value of 2.54μm,so the model fitted the actual situation well.Through the analysis of 3D profile morphology and micromorphology,it was concluded that the optimized kerf surface of Fraxinus mandshurica was smoother,the cell wall was not destroyed and the tracheid was clear.It provides the theoretical basis for wood micromachining.

Effect of laser characteristics on the weld shape and properties of penetration laser weld of BT20 titanium alloy

The laser beam welding of BT20 titanium alloy was conducted to investigate the weld shape, microstructures and properties. The full penetration weld characteristics produced by CO_2 laser and by YAG laser were compared. The results show that the full penetration weld of YAG laser welding closes to “X” shape, and weld of CO_2 laser welding is “nail-head” shape. Those result from special heating mode of laser deep penetration welding. The tension strength of CO_2 laser and YAG laser joints equal to that of the base metal, but the former has better ductility. All welds consist mainly of the acicular α phase and a few β phase in microstructure. The dendritic crystal of CO_2 laser weld is a little finer than YAG laser weld. According the research CO_2 laser is better than YAG laser for welding of BT20 titanium alloy.

Corrosion Resistance of AZ91 Magnesium Alloy after Laser Remelting Treatment

The main objective of the study was the modification of the surface layer of magnesium alloy by the COlaser. The studied material was the commercial AZ91 magnesium alloy. The effectiveness of the alternations caused by the remelting process was verified on the basis of microscopic observation and corrosion investigations, i e, recording of potentiodynamic polarization curves, electrochemical noise measurements and hydrogen evolution rate measurements. For the adopted range of the treatment parameters, favourable changes were observed in the surface layer such as the refinement of structure and more uniform arrangement of individual phases. As a consequence of those favourable structural changes the improvement of the corrosion resistance of the alloy was achieved in comparison to its non-remelted equivalent. For the treated material corrosion rates expressed as corrosion current densities were at least three times lower than the appropriate values for the untreated alloy comparing them for the same period of samples immersion in the test solution. The obtained results have confirmed the effectiveness of the applied surface treatment resulting in favourable changes in the structure and corrosion properties of the AZ91 magnesium alloy.

A Case of Refractory Childhood Glaucoma Secondary to Weill-Marchesani Syndrome:Management with Combined CO_(2) Laser-Assisted Sclerectomy Surgery and Trabeculectomy

A 2-year-old girl was diagnosed as Weill-Marchesani syndrome with typical systemic features of short stature,short and stubby hands and feet,language disorders and mental retardation.He developed bilateral angle closure glaucoma,ectopia lentis and suffered visual loss from the ocular features of Weill-Marchesani syndrome.The child was successfully treated by combined CO_(2) laser-assisted sclerectomy surgery and trabeculectomy.

Combined Treatment with Electrocauterization,Carbon Dioxide Laser,and Microneedle Fractional Radiofrequency for Facial Angiofibromas in Tuberous Sclerosis Complex:A Case Report and Literature Review

Tuberous sclerosis complex is a type of genetic multisystem disease that causes hamartomas in various organs.Facial angiofibromas commonly occur in 80%of patients and are prominently distributed over the cheek,chin,and nasolabial folds with severe disfigurement and emotional distress.Recently,photoelectric devices have been identified for the treatment of angiofibromas with great efficacy and fewer side effects.We report a case of a 42-year-old man with facial angiofibromas,who was treated with a combination of high-frequency electrocauterization,Ultrapulse CO_(2) laser,and microneedle fractional radiofrequency with 7 sessions and a 6-month follow-up.The patient showed great improvement in relation to the elevated lesions and nodules.A low recurrence rate was observed.This is the first study to investigate the efficacy of high-frequency electrocauterization and microneedle fractional radiofrequency in angiofibromas.It may provide an optimal approach for clinicians wherein a combined treatment of various lasers and electric devices is effective for complicated,protuberant,and firm angiofibromas of specific patients.

Three-dimensional transient simulation of CO_(2) laser tissue vaporization and experimental evaluation with a hydrogel phantom

A quantitative analysis method of CO_(2) 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 CO_(2) laser treatments have been proposed,validations of the CO_(2) laser wavelength have been insuffcient.In this study,we demonstrated a tissue vaporization simulation using a CO_(2) 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 CO_(2) 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 CO_(2) laser treatments.

The Characteristics of Glued Tensile Shear Strength Constituted of Wood Cut by CO_(2) Laser

The performance of engineered wood products is highly associated with proper bonding and an efficient cutting method.This paper investigates the influence of CO_(2) laser cutting on the wetting properties,the modified che-mical component of the laser-cut surface,and the strength and adhesive penetration near the bondline.Beech-wood is cut by the laser with varying processing parameters,cutting speeds,gas pressures,and focal point positions.The laser-cut samples were divided into two groups,sanded and non-sanded samples.Polyvinyl acetate adhesive(PVAc)was used to bond the groups of laser-cut samples.After assembly with cold pressing,the tensile shear test was carried out.Numerical modelling was carried out to determine the partial elongation and shear strain of the glue line.Based on this,the shear modulus and linear elasticity of the glue line were estimated.Scan-ning electron microscopy was used to assess the adhesive penetration into the porosity structure of the laser-cut samples,and the depth of the heat-affected zone.The laser-cut surface was analysed by Fourier transform infrared spectroscopy.The wetting properties of the laser-cut surface were investigated by using a contact angle goni-ometer.The numerical model of the strain-stress curve confirmed the experimental model.The highest modulus of the linear elasticity of the glue in the numerical calculation belongs to the joint containing laser-cut samples at a gas pressure of 21(bar).The penetration depth of PVAc adhesive into the porosity structure of the laser-cut sam-ples was similar to that of sawn samples.The deepest heat-affected zone in the laser-cut samples was 150µm.A PVAc drop disappeared immediately on the laser-cut surface without sanding,but gradually on the sanded surface.In contrast,the drop on the sawn surface remained with an angle of 32°–48°.The degradation of hemi-cellulose and lignin was proven by the lower intensity of the C=O and C-O Bonds,compared to the sawn surface.

CO_(2)LASER PLUS PHOTODYNAMIC THERAPY VERSUS CO_(2)LASER IN THE TREATMENT OF CONDYLOMA ACUMINATUM:A RANDOMIZED COMPARATIVE STUDY

To compare the efficacy and safety of CO_(2)laser plus 5-aminolevulinic acid(ALA)photodynamic therapy(PDT)with CO_(2)laser for the treatment of multiple condyloma acuminatum(CA),120 patients with multiple CA were allocated into two groups—combined group(CO_(2)laser plus ALA-PDT,n=60)and CO_(2)laser group(CO_(2)laser plus placebo-PDT,n=60).After CO_(2)laser,a 20%ALA or a placebo solution was applied to the CA area 3 h before illumination with red light(635 nm,100mW/cm^(2),80 J/cm^(2)).The treatment was repeated seven days after the first treatment if the lesions were not completely resolved.The complete response rate,recurrence rate and adverse effects in the two groups were analyzed.After two treatments,the complete response rates in the CO_(2)laser group and combined group were 100%(509/509)and 100%(507/507)in the CA(p>0:05),respectively.The recurrence rates in the CO_(2)laser group and combined group were 44.9%(229/509)and 10.6%(54/507)in the CA(p<0:05),respectively.The adverse effects in CO_(2)laser group was more than that in combined group.The combined group is a more effective treatment for multiple CA compared with CO_(2)laser group.T/S.Style the highlighted text as abstract.

Diagnostics of laser-induced plasma on carbon-based polymer material using atomic and molecular emission spectra

Time-integrated optical emission analysis of laser-induced plasma on Teflon is presented.Plasma was induced under atmospheric pressure air using transversely excited atmospheric CO_(2) laser pulses.Teflon is a C-based polymer that is,among other things,interesting as a substrate for laser-induced breakdown spectroscopy analysis of liquid samples.This study aimed to determine the optimal experimental conditions for obtaining neutral and ionized C spectral lines and C2 and CN molecular band emission suitable for spectrochemical purposes.Evaluation of plasma parameters was done using several spectroscopic techniques.Stark profiles of appropriate C ionic lines were used to determine electron number density.The ratio of the integral intensity of ionic-to-atomic C spectral lines was used to determine the ionization temperature.A spectral emission of C2 Swan and CN violet bands system was used to determine the temperature of the colder,peripheral parts of plasma.We critically analyzed the use of molecular emission bands as a tool for plasma diagnostics and suggested methods for possible improvements.

金刚石砂轮的CO_2脉冲激光修锐研究

利用ＣＯ２激光对树脂结合剂金刚石砂轮片的表面进行了扫描试验，对扫描前后砂轮片的表面三维形貌进行了测试分析，研究了激光脉冲频率和占空比等参数的影响。结果表明，尽管平均扫描能量密度一定，但频率和占空比对修锐效果均会产生影响，其中频率的影响更为显著。同时，通过使用铝工件和砂轮片的相对刻划试验，对不同扫描条件下刻划时的切向力与法向力之比进行了对比分析，发现由于该力比可以有效地反映出砂轮片的切削性能，因此可以用来对修锐效果进行定量评价。

几种CO_2激光切雕机光开关的设计与研究

设计与研究了几种用于ＣＯ２激光切雕机的光开关，并对其性能进行了讨论和比较。

CO_2激光术与手术切除术治疗头皮疣状痣的临床探讨

目的 :用 CO2 激光法与手术切除法治疗头皮疣状痣 ,比较二种方法在治愈疾病及美容效果上的优越性。方法 :根据临床观察皮损形态特征明确诊断头皮疣状痣病例 10 6例 ,二种方法各取5 3例 ,皮损范围约 1.0× 2 .5× 0 .5 cm,采用在局麻下行 CO2 激光术及手术切除术治疗。 CO2 激光利用聚焦光束烧灼患处 ,去除皮损。手术切除法切除皮损。二种手术方法的深度均宜达到真皮浅层。术后 ,前者要求创面暴露 ,每日搽一次金霉素眼膏 ,后者缝合后切口处加压包扎 ,避免局部发生血肿 ,影响创口愈合。结果 :根据评判标准 ,CO2 激光术痊愈率达 96.2 % ,手术切除术痊愈率为 92 .4 %。根据美容效果的评判 :CO2 激光术治疗后毛发生长密度均匀 ,达到好的标准为 90 .6% ,手术切除术达到好的标准为 73.6%。结论 :CO2 激光术与手术切除术二者比较 ,结果证明前者方法简便 。

折叠式准封离型CO_2激光器及其在切割和焊接中的应用

为满足激光切割、焊接对高光束质量激光器的迫切需求 ,开发了一种折叠式准封离型有自主知识产权的高光束质量、高稳定性、高可靠性、低消耗、长寿命千瓦级CO2 激光器。目前已批量生产 ,成功应用于激光切割与焊接生产 ,打破了高光束质量激光器长期被国外产品垄断局面。

点阵CO_(2)激光联合他克莫司软膏治疗稳定期白癜风效果分析

目的:探讨点阵CO_(2)激光联合他克莫司软膏治疗稳定期白癜风对患者白斑面积及美学满意度的影响。方法:选取2022年2月-2023年1月宝鸡市中心医院收治的78例稳定期白癜风患者作为研究对象,采用随机数字表法分为A组(26例)、B组(26例)和C组(26例)。A组给予点阵CO_(2)激光联合他克莫司软膏治疗,B组给予他克莫司软膏,C组给予点阵CO_(2)激光治疗。三组均持续治疗16周并随访3个月。比较三组治疗16周后的临床疗效、复色率、白斑面积及美学满意度,治疗前、治疗16周后的肉眼下皮损情况、免疫功能及炎症反应,随访期间的安全性,预后。结果:治疗16周后,A组、B组、C组总有效率分别为96.15%、69.23%、73.08%,A组高于B、C组(P<0.05)。与治疗前比较,治疗16周后,三组皮损色素岛形成、毛囊周围毛细血管扩张、皮损周围色素的患者占比均升高,A组高于B、C组(P<0.05)。治疗16周后,A组复色率均高于B、C组;A组白斑面积均低于B、C组;A组、B组、C组美学满意率分别为96.15%、65.38%、69.23%,A组高于B、C组(P<0.05)。与治疗前比较,治疗16周后,三组血清CD4^(+)、CD36(+)CD8^(+)、CD4^(+)CD45^(+)水平均升高,且A组高于B、C组,C组高于B组;三组血清CD8+、白细胞介素-17(IL-17)、白细胞介素-22(IL-22)水平均降低,且A组低于B、C组,C组低于B组(P<0.05)。随访期间,三组不良反应发生率比较,差异无统计学意义(P>0.05)。随访3个月后,A、B、C组复发率分别为3.85%、30.77%、15.38%,A组低于B、C组(P<0.05)。结论:在稳定期白癜风的治疗中,点阵CO_(2)激光联合他克莫司软膏治疗可显著提高患者免疫功能,减轻患者炎症反应,并缓解患者皮损症状,减少白斑面积,提高复色率,进而提高患者美学满意度,且安全性良好,复发率较低。