WorldWideScience

Sample records for co2 laser vaporization

  1. Treatment of vulvar intraepithelial neoplasia with CO(2) laser vaporization and excision surgery.

    Science.gov (United States)

    Leufflen, Léa; Baermann, Pauline; Rauch, Philippe; Routiot, Thierry; Bezdetnava, Lina; Guillemin, Francois; Desandes, Emmanuel; Marchal, Frederic

    2013-10-01

    To evaluate the recurrence rate after a single treatment of vulvar intraepithelial neoplasia (VIN) with CO(2) laser vaporization. Fifty women with usual-type or differentiated VIN (grades 2 and 3) treated with CO(2) laser vaporization or surgery excision (cold knife or CO(2) laser) were retrospectively evaluated. Of the 50 patients, 41 (82.0%) had usual-type VIN and 9 (18.0%) had differentiated VIN. Moreover, 24 (48.0%) were treated with surgery excision and 26 (52.0%) underwent CO(2) laser vaporization. Laser-treated patients were significantly younger (p vaporization groups (p vaporization treatment (p vaporization requires regular, close, and extended monitoring.

  2. Laser scar revision: comparison of CO2 laser vaporization with and without simultaneous pulsed dye laser treatment.

    Science.gov (United States)

    Alster, T S; Lewis, A B; Rosenbach, A

    1998-12-01

    Over the past decade, the 585-nm pulsed dye laser (PDL) has been used successfully to treat a variety of cutaneous vascular lesions as well as hypertrophic scars. Laser scar revision has been revolutionized by the recent development of high-energy, pulsed carbon dioxide (CO2) laser systems. These new CO2 lasers allow controlled vaporization of thin layers of skin while minimizing damage to surrounding dermal structures. To determine the effect of a high-energy, pulsed CO2 laser alone and in combination with a 585-nm PDL on nonerythematous hypertrophic scars. Twenty patients with nonerythematous hypertrophic scars were treated with a high-energy, pulsed CO2 laser. One-half of each scar was additionally treated with the 585-nm PDL laser. Sequential clinical and photographic analyses were performed independently by two blinded assessors. In addition, erythema reflectance spectrometry measurements were obtained from the scars before and at regular postoperative intervals. Global assessment scores and erythema spectrometry measurements were significantly improved after laser treatment. Combination CO2 and PDL laser treatment resulted in more significant improvement than CO2 laser irradiation alone. Concomitant use of the high-energy, pulsed CO2 and PDL laser systems was superior to CO2 laser vaporization alone for revision of nonerythematous hypertrophic scars. Once again, the vascular specificity of the 585-nm PDL has been linked to improvement in hypertrophic scar tissue.

  3. Risk factors for treatment failure of CO2 laser vaporization in cervical intraepithelial neoplasia 2.

    Science.gov (United States)

    Yoon, Bo Sung; Seong, Seok Ju; Song, Taejong; Kim, Mi-La; Kim, Mi Kyoung

    2014-07-01

    The aim of our study was to evaluate the risk factors for treatment failure of CO2 laser vaporization in patients with cervical intraepithelial neoplasia 2 (CIN2). Medical records of patients who received either shallow or deep CO2 laser vaporization with biopsy-proven CIN2 during March 2007 to April 2011 were reviewed retrospectively. After laser vaporization, liquid-based cytology and human papilloma virus (HPV) DNA testing were checked in every follow-up visit. Treatment failure was defined when the follow-up biopsy was more than CIN2, needing secondary surgical treatment. During that period, 141 patients with CIN2 underwent CO2 laser vaporization. After laser ablation, 14 of 141 women needed the secondary treatment, a success rate of laser vaporization of 90.1 %. In multivariate analysis, the previous loop electrosurgical excision procedure (LEEP) history (adjusted OR = 13.649; P value = 0.025) and the ablation depth (adjusted OR = 11.279; P value = 0.006) were independent factors associated with treatment failure. Both ablation depth and previous LEEP history were the important factors increasing the risk for the treatment failure of CO2 laser vaporization in CIN2.

  4. CO(2) laser vaporization as primary therapy for human papillomavirus lesions. A prospective observational study.

    Science.gov (United States)

    Savoca, S; Nardo, L G; Rosano, T F; D'Agosta, S; Nardo, F

    2001-12-01

    Human papillomavirus manifestations occur with increased frequency and severity amongst sexually active people. Several therapeutic approaches have been suggested to treat this viral disease. The aim of this prospective observational study was to assess the effectiveness of CO(2) laser vaporization for human papillomavirus warts. Eighty healthy sexually active women with cytologically, colposcopically and histologically diagnosed human papillomavirus urogenital and perianal warts were enrolled and then treated by CO(2) laser (16-18 W). Male partners were also investigated, and interferon-beta was eventually administered. All patients were then followed up for twelve months consecutively. At twelve-month follow-up, warts clearance was observed in 70 (87.5%) women. Recurrence was reported in ten (12.5%) women with multiple partners and affected by flat or endophytic condiloma of the cervix. Moreover, there were no complaints of pain, scar tissue deformity or other side effects. CO(2) laser vaporization is an effective, as well as safe and simple therapeutic approach for treatment of human papillomavirus warts. Its use should be encouraged for condyloma acuminata not associated with malignancy, as well as during pregnancy.

  5. [Comparative study on the effects of LEEP and laser CO(2) vaporization in cervical intraepithelial neoplasia II].

    Science.gov (United States)

    Sun, Lu-Lu; Cao, Dong-Yan; Bian, Mei-Lu; Wei, Li-Hui; Yang, Jia-Xin; Yang, Li; Cheng, Ning-Hai; Wang, You-Fang; Cheng, Xue-Mei; Hu, Li-Jun; Lang, Jing-He; Shen, Keng

    2010-11-23

    to compare the effect and complications of loop electro-surgical excision procedure (LEEP) and laser CO(2) vaporization in the treatment of cervical intraepithelial neoplasia II. a total of 338 CINII women were recruited into this multi-center comparative study. The diagnosis was confirmed by histopathological examination for cervical epithelial cell abnormalities. And colposcopic examination was submitted to LEEP (n = 195) or laser CO(2) vaporization (n = 143) respectively. A post-treatment follow-up of 3, 6 and 12 months was carried out to compare the effect of two methods. among 195 women undergoing LEEP, the frequency of cure, persistent and recurrent CIN was 89.2% (n = 174), 4.1% (n = 8) and 3.6% (n = 7) respectively. And among 143 women receiving laser CO(2) vaporization, the frequency of cure, persistent and recurrent CIN was 86.7% (n = 124), 4.9% (n = 7) and 0.70% (n = 1) respectively. There was no statistical difference in cure rates, persistence or recurrence of CIN (P > 0.05). The recovery time, the operative frequency and intra-operative blood loss were significantly different in two groups. both LEEP and CO(2) vaporization are both effective and reliable for the treatment of cervical intraepithelial neoplasia II. However, pathological specimens may be harvested during LEEP. It is of vital importance to conduct preoperative colposcopic assessment and standard postoperative follow-ups.

  6. CO2 laser resurfacing.

    Science.gov (United States)

    Fitzpatrick, R E

    2001-07-01

    The CO2 Laser offers a variety of unique features in resurfacing facial photodamage and acne scarring. These include hemostasis, efficient removal of the epidermis in a single pass, thermally induced tissue tightening, and safe, predictable tissue interaction. Knowledge of these mechanisms will result in the capability of using the CO2 laser effectively and safely whether the goal is superficial or deep treatment.

  7. Laser CO2 vaporization for high-grade cervical intraepithelial neoplasia: a long-term follow-up series.

    Science.gov (United States)

    Fallani, Maria Grazia; Penna, Carlo; Fambrini, Massimiliano; Marchionni, Mauro

    2003-10-01

    The goal of this study was to evaluate the effectiveness of laser CO(2) vaporization for conservative treatment of ectocervical high-grade cervical intraepithelial neoplasia (CIN) particularly by the evaluation of the reappearance risk of disease in long-term follow-up. One hundred fifty-nine patients were submitted to CO(2) laser vaporization for high-grade CIN and followed up for a minimum of 5 years. Selection of cases, depth of ablation, complications, and cure rate (percentage of treated patients in whom there was no recurrent/persistent high-grade CIN at the 5-year follow-up examination) were retrospectively evaluated. Selected cases for colposcopy were submitted to a 6-mm mean depth of vaporization without intra- or postoperative complications. The cure rate for a single treatment was 97.5% and a satisfactory colposcopic follow-up was possible in 99.4% of treated patients. No case of invasive carcinoma occurred after a mean follow-up of 7.1 years. Four cases (2.5%) were high-grade CIN persistence observed after a mean time of 3.75 months, suggesting incomplete destruction of the deepest part of the lesion involving the glandular crypt base. Long-term follow-up proves that laser CO(2) vaporization still has a place in the treatment of CIN. In selected cases it represents a safe alternative for conization in the treatment of high-grade CIN, but colposcopic expertise is essential for adequate preoperative selection of cases.

  8. Evaluation of different treatment modalities for vulvar intraepithelial neoplasia (VIN): CO(2) laser vaporization, photodynamic therapy, excision and vulvectomy.

    Science.gov (United States)

    Hillemanns, Peter; Wang, Xiuli; Staehle, Stefanie; Michels, Wolfgang; Dannecker, Christian

    2006-02-01

    To evaluate various treatment modalities for vulvar intraepithelial neoplasia (VIN) in relation to possible risk factors for recurrence. Retrospective review of 93 patients with VIN treated by CO(2) laser vaporization, photodynamic therapy with aminolevulinic acid (PDT), excision or vulvectomy. 40.4% of the 47 patients with laser vaporization, 48.1% of 27 patients with PDT, 42% of 12 patients with local excision and none of the 7 patients treated by vulvectomy experienced a relapse within a mean follow-up of 53.7 months. The risk for recurrence significantly increased with VIN grade (P = 0.02), multifocal VIN disease (P = 0.01), multicentric intraepithelial neoplasia (P = 0.05) and high-risk HPV infection (P VIN have high recurrence rates, especially in patients with HPV infection and multifocal disease. Therefore, careful long-term surveillance is mandatory.

  9. Growth dynamics of carbon-metal particles and nanotubes synthesized by CO2 laser vaporization

    Science.gov (United States)

    Kokai, F.; Takahashi, K.; Yudasaka, M.; Iijima, S.

    To study the growth of carbon-Co/Ni particles and single-wall carbon nanotubes (SWNTs) by 20 ms CO2 laser-pulse irradiation of a graphite-Co/Ni (1.2 at.%) target in an Ar gas atmosphere (600 Torr), we used emission imaging spectroscopy and shadowgraphy with a temporal resolution of 1.67 ms. Wavelength-selected emission images showed that C2 emission was strong in the region close to the target (within 2 cm), while for the same region the blackbody radiation from the large clusters or particles increased with increasing distance from the target. Shadowgraph images showed that the viscous flow of carbon and metal species formed a mushroom or a turbulent cloud spreading slowly into the Ar atmosphere, indicating that particles and SWNTs continued to grow as the ejected material cooled. In addition, emission imaging spectroscopy at 1200 °C showed that C2 and hot clusters and particles with higher emission intensities were distributed over much wider areas. We discuss the growth dynamics of the particles and SWNTs through the interaction of the ambient Ar with the carbon and metal species released from the target by the laser pulse.

  10. CO2 laser vaporization in the treatment of cervical human papillomavirus infection in women with abnormal Papanicolaou smears

    DEFF Research Database (Denmark)

    Ruge, S; Felding, C; Skouby, S O

    1992-01-01

    In a randomized study, we have evaluated the treatment of cervical human papillomavirus (HPV) lesions by CO2 laser vaporization. Fifty patients with abnormal Papanicolaou smears and histological evidence of cervical HPV infection associated or not with cervical intraepithelial neoplasia (CIN) grade...... I were randomized to either a treatment or a control group. The cervical swabs were obtained every 3 months in both groups and examined for HPV type 16 DNA by the polymerase chain reaction. After a follow-up period of 12 months no significant differences were found between the laser treatment...... in their cervical smears at 12 months' follow-up was identical in the two groups, supporting the hypothesis that HPV is a persistent infection during which the virus is widespread in the vaginal epithelium....

  11. Different CO2 laser vaporization protocols for the therapy of oral precancerous lesions and precancerous conditions: a 10-year follow-up.

    Science.gov (United States)

    Deppe, Herbert; Mücke, Thomas; Hohlweg-Majert, Bettina; Hauck, Wolfgang; Wagenpfeil, Stefan; Hölzle, Frank

    2012-01-01

    Use of the CO(2) laser (λ = 10.6 μm, continuous wave, defocused) is an established procedure for the treatment of premalignant lesions. Through employment of the sp-mode as well as scanners, thermal laser effects can be reduced but, on the other hand, a lesser degree of destruction of dysplastic cells could lead to an increased recurrence rate. The purpose of this study was to prospectively evaluate the recurrence rates resulting from different methods of CO(2) laser vaporization. From May 1995 to May, 2005, 145 patients with a total of 148 premalignant lesions of the oral mucosa were treated in a prospective clinical study. Sixty-two lesions in 62 patients were vaporized with the defocused CO(2) laser (group 1). In a further 45 lesions (43 patients, group 2), a scanner was additionally employed. In the remaining 41 lesions (40 patients, group 3), vaporization was carried out in the sp-mode in which the scanner was also used. In September, 2005, recurrence rates in the three groups were evaluated. Use of the scanner in sp-mode resulted in the most irregular tissue vaporization. This can be accounted for by the irregular paths of the laser beam and the pulsed delivery of the laser energy. Statistically significant lowest recurrence rates were yielded by the defocused cw-technique followed by the cw-scanner and the sp-mode. These results indicate that for CO(2) laser treatment of premalignant lesions of the oral mucosa, the best results can be achieved with the defocused technique. It may be assumed that other methods with lesser penetration of thermal effects (e.g. sp, scanner) do not reach the deeper-lying cells and, consequently, render higher rates of recurrence.

  12. CO2 laser cutting

    CERN Document Server

    Powell, John

    1998-01-01

    The laser has given manufacturing industry a new tool. When the laser beam is focused it can generate one of the world's most intense energy sources, more intense than flames and arcs, though similar to an electron beam. In fact the intensity is such that it can vaporise most known materials. The laser material processing industry has been growing swiftly as the quality, speed and new manufacturing possibilities become better understood. In the fore of these new technologies is the process of laser cutting. Laser cutting leads because it is a direct process substitu­ tion and the laser can usually do the job with greater flexibility, speed and quality than its competitors. However, to achieve these high speeds with high quality con­ siderable know how and experience is required. This information is usually carefully guarded by the businesses concerned and has to be gained by hard experience and technical understanding. Yet in this book John Powell explains in lucid and almost non­ technical language many o...

  13. Enhanced chemical vapor deposition of diamond by wavelength-matched vibrational excitations of ethylene molecules using tunable CO2 laser irradiation

    Science.gov (United States)

    Ling, H.; Xie, Z. Q.; Gao, Y.; Gebre, T.; Shen, X. K.; Lu, Y. F.

    2009-03-01

    Wavelength-matched vibrational excitations of ethylene (C2H4) molecules using a tunable carbon dioxide (CO2) laser were employed to significantly enhance the chemical vapor deposition (CVD) of diamond in open air using a precursor gas mixture of C2H4, acetylene (C2H2), and oxygen (O2). The CH2-wag vibration mode (ν7) of the C2H4 molecules was selected to achieve the resonant excitation in the CVD process. Both laser wavelengths of 10.591 and 10.532 μm were applied to the CVD processes to compare the C2H4 excitations and diamond depositions. Compared with 10.591 μm produced by common CO2 lasers, the laser wavelength of 10.532 μm is much more effective to excite the C2H4 molecules through the CH2-wag mode. Under the laser irradiation with a power of 800 W and a wavelength of 10.532 μm, the grain size in the deposited diamond films was increased by 400% and the film thickness was increased by 300%. The quality of the diamond crystals was also significantly enhanced.

  14. The effect of CO2 laser treatment on skin tissue.

    Science.gov (United States)

    Baleg, Sana Mohammed Anayb; Bidin, Noriah; Suan, Lau Pik; Ahmad, Muhammad Fakarruddin Sidi; Krishnan, Ganesan; Johari, Abd Rahman; Hamid, Asma

    2015-09-01

    The aim of this study was to evaluate the effects of multiple pulses on the depth of injury caused by CO2 laser in an in vivo rat model. A 10 600-nm CO2 laser was applied to rat skin, with one side of the rat dorsal skin being exposed, leaving the other side as a control. All of the various laser pulses tested led to gradual loss of epidermal thickness as well as a dramatic increase in thermal damage depth. Collagen coagulation was most effective with ten pulses of CO2 laser, while the strength of irradiated skin tissue increased as the influence of the laser increased. Fundamental laser-skin interaction effects were studied using a CO2 laser. The photodamaged areas obtained from laser interaction were recorded via couple charge device video camera and analyzed via ImageJ software. Photodamage induced by CO2 laser is due to photothermal effects, which involve burning and vaporizing mechanisms to ablate the epidermis layer. The burning area literally expands and penetrates deep into the dermis layer, subsequently causing collagen coagulation. This fundamental study shows in detail the effect of CO2 laser interaction with skin. The CO2 attributed severe burning, producing deep coagulation, and induced strength to treated skin. © 2015 Wiley Periodicals, Inc.

  15. The Role of the CO2 Laser and Fractional CO2 Laser in Dermatology.

    Science.gov (United States)

    Omi, Tokuya; Numano, Kayoko

    2014-03-27

    Tremendous advances have been made in the medical application of the laser in the past few decades. Many diseases in the dermatological field are now indications for laser treatment that qualify for reimbursement by many national health insurance systems. Among laser types, the carbon dioxide (CO2) laser remains an important system for the dermatologist. The lasers used in photosurgery have wavelengths that differ according to their intended use and are of various types, but the CO2 laser is one of the most widely used lasers in the dermatology field. With its wavelength in the mid-infrared at 10,600 nm, CO2 laser energy is wellabsorbed in water. As skin contains a very high water percentage, this makes the CO2 laser ideal for precise, safe ablation with good hemostasis. In addition to its efficacy in ablating benign raised lesions, the CO2 laser has been reported to be effective in the field of esthetic dermatology in the revision of acne scars as well as in photorejuvenation. With the addition of fractionation of the beam of energy into myriad microbeams, the fractional CO2 laser has offered a bridge between the frankly full ablative indications and the nonablative skin rejuvenation systems of the 2000s in the rejuvenation of photoaged skin on and off the face. The CO2 laser remains an efficient, precise and safe system for the dermatologist. Technological advances in CO2 laser construction have meant smaller spot sizes and greater precision for laser surgery, and more flexibility in tip sizes and protocols for fractional CO2 laser treatment. The range of dermatological applications of the CO2 laser is expected to continue to increase in the future.

  16. Clinical application of CO2 laser in periodontal treatment

    Science.gov (United States)

    Hayase, Yasuhiro

    1994-09-01

    CO2 lasers in particular are expected to have many dental applications because the CO2 laser beam exhibits strong tissue transpirative actions, such as instant coagulation, carbonization, and vaporization, and because its wavelength at 10.6 micrometers is fully absorbed by water so that the ability to make precise incisions with a high degree of safety is excellent, without damaging the deep tissues. However, clinical application of the CO2 laser has been slowed since a fiber which can conduct the laser beam to the oral cavity has only recently developed. This new fiber is an extremely flexible fiber with a minimum bending radius of 20 mm and utilizes pulse wave modes that have improved the handling characteristics in the mouth, and this has enabled us to apply the CO2 laser to a variety of periodontal conditions. The aim of this study was to evaluate the effectiveness of CO2 lasers for the early treatment of inflammation and pain relief of acute periodontitis, curettage of periodontal pockets, healing after excision of gingiva, and early improvement of gingivitis.

  17. Cutting weeds with a CO2 laser

    DEFF Research Database (Denmark)

    Heisel, T.; Schou, Jørgen; Christensen, S.

    2001-01-01

    Stems of Chenopodium album. and Sinapis arvensis. and leaves of Lolium perenne. were cut with a CO2 laser or with a pair of scissors. Treatments were carried out on greenhouse-grown pot plants at three different growth stages and at two heights. Plant dry matter was measured 2 to 5 weeks after...... treatment. The relationship between dry weight and laser energy was analysed using a non-linear dose-response regression model. The regression parameters differed significantly between the weed species. At all growth stages and heights S. arvensis was more difficult to cut with a CO2 laser than C. album....... When stems were cut below the meristems, 0.9 and 2.3 J mm(-1) of CO2 laser energy dose was sufficient to reduce by 90% the biomass of C. album and S. arvensis respectively. Regrowth appeared when dicotyledonous plant stems were cut above meristems, indicating that it is important to cut close...

  18. Flash scanning the CO2 laser: a revival of the CO2 laser in plastic surgery

    Science.gov (United States)

    Lach, Elliot

    1994-09-01

    The CO2 laser has broad clinical application yet also presents a number of practical disadvantages. These drawbacks have limited the success and utilization of this laser in plastic surgery. Flashscanner technology has recently been used for char-free CO2 laser surgery of the oropharynx, the external female genital tract, and perirectal mucosa. A commercially available optomechanical flashscanner unit `Swiftlase,' was adapted to a CO2 laser and used for treatment in numerous plastic surgical applications. Conditions and situations that were treated in this study included generalized neurofibromatosis, tuberous sclerosis, rhinophyma, viral warts, breast reconstruction, and deepithelialization prior to microsurgery or local flap transfer and/or skin graft placement. There were no significant wound healing complications. Some patients previously sustained undue scarring from conventional CO2 laser surgery. Conservative, primarily ablative CO2 laser surgery with the Swiftlase has usefulness for treatment of patients in plastic surgery including those that were previously unsuccessfully treated.

  19. CW CO2 Laser Induced Chemical Reactions

    Science.gov (United States)

    Pola, Joseph

    1989-05-01

    CW CO2 laser driven reactions between sulfur hexafluoride and carbon oxide, carbon suboxide, carbonyl sulfide and carbon disulfide proceed at subatmospheric pressures and yield fluorinated carbon compounds and sulfur tetrafluoride. CW CO2 laser driven reactions of organic compounds in the presence of energy-conveying sulfur hexafluoride show reaction course different from that normally observed due to elimination of reactor hot surface effects. The examples concern the decomposition of polychlorohydrocarbons, 2-nitropropane, tert.-butylamine, allyl chloride, spirohexane, isobornyl acetate and the oxidation of haloolefins. CW CO2 laser induced fragmentation of 1-methyl-l-silacyclobutanes and 4-silaspiro(3.4)octane in the presence of sulfur hexafluoride is an effective way for preparation and deposition of stable organosilicon polymers.

  20. Bartholin's gland cysts: management with carbon-dioxide laser vaporization Cistos da glândula de Bartholin: tratamento com vaporização laser com CO2

    Directory of Open Access Journals (Sweden)

    Ana Cristina Neves Figueiredo

    2012-12-01

    Full Text Available PURPOSE: To evaluate the effectiveness, recurrence rate, and complications of carbon-dioxide laser vaporization in the treatment of Bartholin's gland cysts. METHODS: A retrospective study including 127 patients with symptomatic Bartholin' gland cysts submitted to carbon-dioxide laser vaporization at our institution from January 2005 to June 2011. Patients with Bartholin's gland abscesses and those suspected of having neoplasia were excluded. All procedures were performed in an outpatient setting under local anaesthesia. Clinical records were reviewed for demographic characteristics, anatomic parameters, intraoperative and postoperative complications, and follow-up data. Data were stored and analyzed in Microsoft Excel® 2007 software. A descriptive statistical analysis was performed, and its results were expressed as frequency (percentage or mean±standard deviation. Complication, recurrence, and cure rates were calculated. RESULTS: The mean age of the patients was 37.3±9.5 years-old (range from 18 to 61 years-old. Seventy percent (n=85 of them were multiparous. The most common symptom was pain and 47.2% (n=60 of patients had a history of previous medical and/or surgical treatment for Bartholin's gland abscesses. Mean cyst size was 2.7±0.9 cm. There were three (2.4% cases of minor intraoperative bleeding. Overall, there were 17 (13.4% recurrences within a mean of 14.6 months (range from 1 to 56 months: ten Bartholin's gland abscesses and seven recurrent cysts requiring reintervention. The cure rate after single laser treatment was 86.6%. Among the five patients with recurrent disease that had a second laser procedure, the cure rate was 100%. CONCLUSIONS: At this institution, carbon-dioxide laser vaporization seems to be a safe and effective procedure for the treatment of Bartholin's gland cysts.OBJETIVO: Avaliar a eficácia, a taxa de recorrência e as complicações da vaporização laser com CO2 no tratamento dos cistos da glândula de

  1. CO2 laser therapy of rhinophyma

    Science.gov (United States)

    Voigt, Peggy; Jovanovic, Sergije; Sedlmaier, Benedikt W.

    2000-06-01

    Laser treatment of skin changes has become common practice in recent years. High absorption of the CO2 laser wavelength in water is responsible for its low penetration dpt in biological tissue. Shortening the tissue exposure time minimizes thermic side effects of laser radiation such as carbonization and coagulation. This can be achieved with scanner systems that move the focused laser beam over a defined area by microprocessor-controlled rapidly rotating mirrors. This enables controlled and reliable removal of certain dermal lesions, particularly hypertrophic scar/span>s, scars after common acne, wrinkles and rhinophyma. Laser ablation of rhinophyma is a stress-minimizing procedure for the surgeon and the patient, since it is nearly bloodless and can be performed under local anaesthesia. Cosmetically favorable reepithelization of the lasered surfaces is achieved within a very short period of time.

  2. Analytical model for CO(2) laser ablation of fused quartz.

    Science.gov (United States)

    Nowak, Krzysztof M; Baker, Howard J; Hall, Denis R

    2015-10-10

    This paper reports the development of an analytical model, with supporting experimental data, which quite accurately describes the key features of CO2 laser ablation of fused silica glass. The quantitative model of nonexplosive, evaporative material removal is shown to match the experimental data very well, to the extent that it can be used as a tool for ablative measurements of absorption coefficient and vaporization energy. The experimental results indicated that a minimum of 12  MJ kg-1 is required to fully vaporize fused quartz initially held at room temperature, which is in good agreement with the prediction of the model supplied with input data available in the literature. An optimal window for the machining of fused quartz was revealed in terms of pulse duration 20-80 μs and CO2 laser wavelength optimized for maximum absorption coefficient. Material removal rates of 0.33 μm per J cm-2 allow for a high-precision depth control with modest laser stability. The model may also be used as a parameter selection guide for CO2 laser ablation of fused silica or other materials of similar thermophysical properties.

  3. Plasma Arc Augmented CO2 laser welding

    DEFF Research Database (Denmark)

    Bagger, Claus; Andersen, Mikkel; Frederiksen, Niels

    2001-01-01

    In order to reduce the hardness of laser beam welded 2.13 mm medium strength steel CMn 250, a plasma arc has been used simultaneously with a 2.6 kW CO2 laser source. In a number of systematic laboratory tests, the plasma arc current, plasma gas flow and distance to the laser source were varied...... with all laser parameters fixed. The welds were quality assessed and hardness measured transversely to the welding direction in the top, middle and root of the seam. In the seams welded by laser alone, hardness values between 275 and 304 HV1 were measured, about the double of the base material, 150 HV1...

  4. A study into CO2 laser cutting process

    Science.gov (United States)

    Yilbas, B. S.

    To improve the laser cutting process, the modeling of the heating mechanism is essential. In the present study a mathematical modeling of CO2 laser cutting process is introduced and numerical solution of the heat transfer equation is obtained. The melting front velocities at different laser output power and workpiece thicknesses are predicted. The temporal development of the melting front profile is computed. The study is extended to include the experimental study of the transient behavior of the vapor ejected from the kerf in the initial stage of the cutting process. To achieve this two methods namely He-Ne laser transmittance and fiber-optic methods are introduced. It is found that the melting front velocity is high in the early stage of the cutting process which agrees with the experimental findings. Zusammenfassung Zur Verbesserung des Laser-Schneideprozesses ist eine Modellvorstellung bezüglich des Aufheizmechanismus erforderlich, die in dieser Untersuchung in einer mathematischen Modellierung des CO2-Laser-Schneidvorgangs besteht, womit numerische Lösungen der Wärmeübergangsgleichung gewonnen werden. Die Schmelzfrontgeschwindigkeit ergibt sich dabei als Funktion der Laser-Leistung und der Werkstückdicken. Auch wird die zeitliche Entwicklung der Schmelzfrontprofile berechnet. In Erweiterung der Studie erfogt die experimentelle Untersuchung des instationären Dampfaustrags an der Kerbe zu Beginn des Schneidprozesses, wobei zwei Methoden zum Einsatz kommen: He-Ne-Laser Transmittanz und faseroptische Techniken. Die rechnerisch vorausgesagte hohe Schmelzfrontgeschwindigkeit zu Beginn des Schneidprozesses wird durch den experimentellen Befund bestätigt.

  5. High gain, multiatmosphere CO2 laser amplifier

    Science.gov (United States)

    Stuart, G. C.; Houtman, H.; Meyer, J.

    1987-02-01

    A novel TE discharge, 15-mm aperture, multiatmosphere, CO2 laser amplifier is described, with measured electrical characteristics and gain measurements on the 9.294-micron, 9R (16) line. The electrical circuit used in this amplifier is a realistic alternative to the Marx bank or conventional LC inversion circuit and, similarly, it would be useful for excitation of other gas lasers as well. This automatically preionized, double-sided, fourfold LC inversion circuit uses only one spark gap, and it is shown to provide small-signal gains of 5.7 percent/cm, at 120 J/l atm and 10 atm. The generalization to an n-stage device, which would be suitable for higher pressures, and larger apertures, is discussed.

  6. Phase Locking of CO(2) Lasers.

    Science.gov (United States)

    Weingartner, W; Schröder, K; Schuöcker, D

    2001-05-20

    A method of phase locking two CO(2) lasers by radiation exchange is presented. This phase-locking was achieved by use of a copper prism as a beam folding device in the resonators and extraction of the output radiation by a common output coupler. Energy exchange led to a phase-locked state if several locking conditions were fulfilled. The amount of radiation injected from one resonator to the second cavity could be adjusted by movement of the prism. The influence of the strength of coupling on the locking range was studied. The beat signal between the two unlocked lasers could be measured, whereas in the case of phase-locked operation twice the intensity was detected. Despite the inclusion of several assumptions, a simplified mathematical model delivered good agreement between calculated and experimental results.

  7. CO2 laser resurfacing of the face and neck.

    Science.gov (United States)

    Goldman, M P

    2001-05-01

    Laser resurfacing with the short-pulsed, high-energy CO2 laser has been used to treat photodamaged skin and acne scars. Efficacy and safety have been demonstrated with this technique since 1992. Newer treatment methods, including sequential or combination treatment with the Er:YAG laser have led to increased efficacy with a decrease in adverse sequelae. This article details the author's experience with CO2 laser resurfacing and promotes the use of sequential CO2/Er:YAG laser resurfacing.

  8. CO2 laser welding of magnesium alloys

    Science.gov (United States)

    Dhahri, Mohammed; Masse, Jean Eric; Mathieu, J. F.; Barreau, Gerard; Autric, Michel L.

    2000-02-01

    Metallic alloys with a low mass density can be considered to be basic materials in aeronautic and automotive industry. Magnesium alloys have better properties than aluminum alloys in respect of their low density and high resistance to traction. The main problems of magnesium alloy welding are the inflammability, the crack formation and the appearance of porosity during the solidification. The laser tool is efficient to overcome the difficulties of manufacturing by conventional processing. Besides, the laser processing mainly using shielding gases allows an effective protection of the metal against the action of oxygen and a small heat affected zone. In this paper, we present experimental results about 5 kW CO2 laser welding of 4 mm-thick magnesium alloy plates provided by Eurocopter France. The focused laser beam has about 0.15 mm of diameter. We have investigated the following sample: WE43, alloy recommended in aeronautic and space applications, is constituted with Mg, Y, Zr, rare earth. More ductile, it can be used at high temperatures until 250 degrees Celsius for times longer than 5000 hours without effects on its mechanical properties. A sample of RZ5 (French Norm: GZ4TR, United States Norm ZE41) is composed of Mg, Zn, Zr, La, rare earth. This alloy has excellent properties of foundry and it allows to the realization of components with complex form. Also, it has a good resistance and important properties of tightness. The parameters of the process were optimized in the following fields: laser power: 2 to 5 kW, welding speed: 1 to 4.5 m/min, focal position: -3 mm to +3 mm below or on the top of the metal surface, shielding gas: helium with a flow of 10 to 60 l/min at 4 bars. Metallurgical analyses and mechanical control are made (macroscopic structure, microscopic structure, interpretations of the structures and localization of possible defects, analyse phases, chemical composition, hardness, tensile test etc.) to understand the parameters influence of welding

  9. THE HIGH GAIN CO2 LASER BY EFFECTIVE MIXING OF N2 AND CO2 GAS

    OpenAIRE

    Hara, H.; Fujisawa, A.

    1980-01-01

    A high-gain CO2 laser is described in which vibrationally excited N2 gas and cold CO2 gas are mixed effectively by means of the diffusion of CO2 gas into N2 gas. By using different types of mixing techniques, a maximum gain of 11 m-1 was obtained when CO2 gas was injected parallel to the expanding N2 gas flow. An output power of 4 W was obtained from an 1.2 cm active length. In addition, He gas addition to the N2 gas flow was found to decrease the small-signal gain with increasing He gas flow...

  10. Fractional CO2 laser resurfacing for atrophic acne scars

    DEFF Research Database (Denmark)

    Hedelund, Lene; Haak, Christina Skovbølling; Togsverd-Bo, Katrine

    2012-01-01

    The treatment of acne scars with fractional CO(2) lasers is gaining increasing impact, but has so far not been compared side-by-side to untreated control skin.......The treatment of acne scars with fractional CO(2) lasers is gaining increasing impact, but has so far not been compared side-by-side to untreated control skin....

  11. Clinical effects of CO2 laser on equine diseases

    Science.gov (United States)

    Lindholm, Arne; Svensson, Ulf; Collinder, Eje

    2002-10-01

    CO2 lasers has been used for five years at Malaren Equine Hospital, as an alternative treatment of some equine diseases. The application of CO2 laser has been studied for evaluation of its appropriateness for treatment of the equine diseases sarcoids, lameness in fetlock joints or pulmonary haemorrhage. During the last five years, above 100 equine sarcoids have been removed by laser surgery (CO2 laser) and so far resulting in significantly few recurrences compared with results from usual excision surgery. In one study, acute traumatic arthritis in fetlock joints was treated three times every second day with defocalised CO2 laser. The therapeutic effectiveness of CO2 laser in this study was better than that of the customary therapy with betamethasone plus hyaluronan. During one year, chronic pulmonary bleeders, namely exercise induced pulmonary haemorrhage, has been treated with defocalised CO2 laser. Six race horses have been treated once daily during five days. Until now, three of these horses have subsequently been successfully racing and no symptoms of pulmonary haemorrhage have been observed. These studies indicate that CO2 laser might be an appropriate therapy on sarcoids and traumatic arthritis, and probably also on exercise induced pulmonary haemorrhage. Other treatments for this pulmonary disease are few.

  12. Comparison of CO2 Laser Cutting with Different Laser Sources

    DEFF Research Database (Denmark)

    Ketting, Hans-Ole; Olsen, Flemmming Ove

    1996-01-01

    This paper contains CO2 laser cutting results in mild and stainless steel with different laser sources. The main factors which affect the cutting speed and quality are the power, the cutting gas and focal point conditions. Keeping the power and cutting gas constant, the focal point conditions have...... size,for the maximum cutting speed. One of the 7 laser sources with different focal length and thus different minimum spot size, was then used to investigate more in details the importance of the focal spot size cutting stainless steel with high pressure nitrogen. It looks as if there is a strong...... been varied with respect to size and power density.In the introduction a theoretical model is presented, showing that the cutting speed is inverse proportional to the width of the cut kerf in a given material, and the definition of the Beam Quality Factor is introduced.In the next chapter this theory...

  13. Medical Applications Of CO2 Laser Fiber Optics

    Science.gov (United States)

    McCord, R. C.

    1981-07-01

    In 1978, Hughes Laboratories reported development of fiber optics that were capable of transmitting CO2 laser energy. These fibers are now being tested for medical applications. Wide ranging medical investigation with CO2 lasers has occurred during the twelve years since the first observations of laser hemostasis. Specialists in ophthalmology, neurosurgery, urology, gynecology, otolaryngology, maxillo-facial/plastic surgery, dermatology, and oncology among others, have explored its use. In principle, all these specialists use CO2 laser radiation at 10.6 microns to thermally destroy diseased tissues. As such, CO2 lasers compare and compete with electrosurgical devices. The fundamental difference between these modalities lies in how they generate heat in treated tissue.

  14. Studies on CO2-laser Hybrid-Welding of Copper

    DEFF Research Database (Denmark)

    Nielsen, Jakob Skov; Olsen, Flemming Ove; Bagger, Claus

    2005-01-01

    CO2-laser welding of copper is known to be difficult due to the high heat conductivity of the material and the high reflectivity of copper at the wavelength of the CO2-laser light. THis paper presents a study of laser welding of copper, applying laser hybrid welding. Welding was performed...... as a hybrid CO2-laser and GTAW welding process in 2 mm pure copper sheets. The purpose was to identify maximum welding speeds for the three independent welding processes, i.e. GTAW alone, laser alone and combined processes. After welding, representative welds were quality assesed according to inernational...... norms. The paper describes the results obtained, showing significant productivity improvements and good weld qualities applying laser hybrid welding....

  15. Thermal injuries as a result of CO2 laser resurfacing.

    Science.gov (United States)

    Grossman, A R; Majidian, A M; Grossman, P H

    1998-09-01

    CO2 laser resurfacing of the face for fine wrinkles has gained great popularity over a short period of time. The use of the CO2 laser has proven to be effective in reducing or eliminating fine wrinkles. This tool in the surgeon's armamentarium has been added to those of dermabrasion and chemical peel. The theoretical advantage of the use of the CO2 laser for resurfacing has been better accuracy and reportedly more control of the depth of penetration. The use of the CO2 laser has been welcomed by many cosmetic surgeons. Until now, there have been few reported cases of complications with the use of the CO2 laser. To many, this would sound too good to be true; unfortunately, that is the case. The CO2 laser is a high-energy machine that can indeed cause thermal injury. This thermal injury can result in deep burns to the skin and hypertrophic scarring. We feel this is more common than is currently being reported, and we share our experience as a burn and wound care referral service. During an 18-month period, 20 consecutive patients were referred to our practice who had received injuries from the CO2 laser resurfacing laser. We present here in this review a summary of those injuries. The CO2 resurfacing laser is a very effective tool for the treatment of fine wrinkles, but it is not without the potential for serious complications. We urge caution with the use of the laser and prompt recognition and treatment of thermal injury to the skin.

  16. Comparison the efficacy of ablative CO2 laser and fractional CO2 laser on the healing of cutaneous leishmaniasis scars.

    Science.gov (United States)

    Nilforoushzadeh, Mohammad Ali; Minaravesh, Shahriar; Jaffary, Fariba; Siadat, Amir Hossein; Haftbaradaran, Elaheh

    2014-01-01

    The aim of this study is to compare ablative CO2 laser with fractional CO2 laser on healing of the wound and the size of cutaneous leishmaniasis scars. This prospective randomized clinical trial study was done on 120 patients in two groups evaluated in Sedigheh Tahereh Hospital in Isfahan. The patients in case group underwent one session ablative CO2 laser for treatment of leishmaniasis scars and the patients in control group underwent six 3-weeks interval sessions fractional CO2 laser for treatment of leishmaniasis scars. All cases were evaluated from size and other aspects of scar by a questionnaire, and before and 6 months after photos were evaluated by blinded dermatologist. The data collected in the check list was then analyzed by t-test and Chi-square with SPSS 20. There were 60 people in case group and 60 in control group. The mean age was 27.21 ± 11.2. Our results show that fractional CO2 laser is better than ablative CO2 laser in various aspect of treatment of leishmaniasis scars (P ablative CO2 laser in variants aspect of treatment of leishmaniasis scars.

  17. A 10 cm aperture, high quality TEA CO2 laser

    NARCIS (Netherlands)

    Ernst, G.J.

    1982-01-01

    Experiments have been performed on a corona preionization type 10 cm aperture TEA CO2 laser. For a CO2:N2:He=1: 1: 7: mixture an output energy of 34 joule per liter and for a 1 : 1 : 10 mixture 40 joule per liter could be obtained. The overall efficiency is about 18%. The time behaviour of the

  18. Airborne Lidar for Simultaneous Measurement of Column CO2 and Water Vapor in the Atmosphere

    Science.gov (United States)

    Singh, Upendra N.; Petros, Mulugeta; Refaat, Tamer F.; Antill, Charles W.; Remus, Ruben; Yu, Jirong

    2016-01-01

    The 2-micron wavelength region is suitable for atmospheric carbon dioxide (CO2) measurements due to the existence of distinct absorption feathers for the gas at this particular wavelength. For more than 20 years, researchers at NASA Langley Research Center (LaRC) have developed several high-energy and high repetition rate 2-micron pulsed lasers. This paper will provide status and details of an airborne 2-micron triple-pulse integrated path differential absorption (IPDA) lidar. The development of this active optical remote sensing IPDA instrument is targeted for measuring both CO2 and water vapor (H2O) in the atmosphere from an airborne platform. This presentation will focus on the advancement of the 2-micron triple-pulse IPDA lidar development. Updates on the state-of-the-art triple-pulse laser transmitter will be presented including the status of seed laser locking, wavelength control, receiver telescope, detection system and data acquisition. Future plans for the IPDA lidar system for ground integration, testing and flight validation will also be presented.

  19. Airborne lidar for simultaneous measurement of column CO2 and water vapor in the atmosphere

    Science.gov (United States)

    Singh, Upendra N.; Petros, Mulugeta; Refaat, Tamer F.; Antill, Charles W.; Remus, Ruben; Yu, Jirong

    2016-10-01

    The 2-micron wavelength region is suitable for atmospheric carbon dioxide (CO2) measurements due to the existence of distinct absorption feathers for the gas at this particular wavelength. For more than 20 years, researchers at NASA Langley Research Center (LaRC) have developed several high-energy and high repetition rate 2-micron pulsed lasers. This paper will provide status and details of an airborne 2-micron triple-pulse integrated path differential absorption (IPDA) lidar. The development of this active optical remote sensing IPDA instrument is targeted for measuring both CO2 and water vapor (H2O) in the atmosphere from an airborne platform. This presentation will focus on the advancement of the 2-micron triple-pulse IPDA lidar development. Updates on the state-of-the-art triple-pulse laser transmitter will be presented including the status of seed laser locking, wavelength control, receiver telescope, detection system and data acquisition. Future plans for the IPDA lidar system for ground integration, testing and flight validation will also be presented.

  20. Isotope selective analysis of CO2 with tunable diode laser (TDL) spectroscopy in the NIR

    OpenAIRE

    Hörner, Gerald; Lau, Steffen; Kantor, Zoltan; Löhmannsröben, Hans-Gerd

    2006-01-01

    The performance of a home-built tunable diode laser (TDL) spectrometer, aimed at multi-line detection of carbon dioxide, has been evaluated and optimized. In the regime of the (3001)III / (000) band of 12CO2 around 1.6 μm, the dominating isotope species 12CO2, 13CO2, and 12C18O16O were detected simultaneously without interference by water vapor. Detection limits in the range of few ppmv were obtained for each species utilizing wavelength modulation (WM) spectroscopy with balanced detection in...

  1. Application of CO2 laser for electronic components soldering

    Science.gov (United States)

    Mascorro-Pantoja, J.; Soto-Bernal, J. J.; Nieto-Pérez, M.; Gonzalez-Mota, R.; Rosales-Candelas, I.

    2011-10-01

    Laser provides a high controllable and localized spot for soldering joint formation and this is a valuable tool in Sn/Pb Soldering process on electronic industry, in recent years, laser beam welding has become an emerging welding technique, the use of laser in welding area is a high efficiency method. A 60 Watts CO2 continuous laser was used on this study, during welding experimental results indicated the laser could significantly improve speed and weld quality. In this work, the welding interactions of CO2 laser with Sn/Pb wire have been investigated in details through varying the energy ratios of laser. And at the same time, the effect of distance from laser spot to material.

  2. 2-Micron Laser Transmitter for Coherent CO2 DIAL Measurement

    Science.gov (United States)

    Singh, Upendra N.; Bai, Yingxin; Yu, Jirong

    2009-01-01

    Carbon dioxide (CO2) has been recognized as one of the most important greenhouse gases. It is essential for the study of global warming to accurately measure the CO2 concentration in the atmosphere and continuously record its variation. A high repetition rate, highly efficient, Q-switched 2-micron laser system as the transmitter of a coherent differential absorption lidar for CO2 measurement has been developed in NASA Langley Research Center. This laser system is capable of making a vertical profiling of CO2 from ground and column measurement of CO2 from air and space-borne platform. The transmitter is a master-slave laser system. The master laser operates in a single frequency, either on-line or off-line of a selected CO2 absorption line. The slave laser is a Q-switched ring-cavity Ho:YLF laser which is pumped by a Tm:fiber laser. The repetition rate can be adjusted from a few hundred Hz to 10 kHz. The injection seeding success rate is from 99.4% to 99.95%. For 1 kHz operation, the output pulse energy is 5.5mJ with the pulse length of 50 ns. The optical-to-optical efficiency is 39% when the pump power is 14.5W. A Ho:YLF laser operating in the range of 2.05 micrometers can be tuned over several characteristic lines of CO2 absorption. Experimentally, a diode pumped Ho:Tm:YLF laser has been successfully used as the transmitter of coherent differential absorption lidar for the measurement of CO2 with a repetition rate of 5 Hz and pulse energy of 75 mJ. For coherent detection, high repetition rate is required for speckle averaging to obtain highly precise measurements. However, a diode pumped Ho:Tm:YLF laser can not operate in high repetition rate due to the large heat loading and up-conversion. A Tm:fiber laser pumped Ho:YLF laser with low heat loading can operate in high repetition rate. A theoretical model has been established to simulate the performance of Tm:fiber laser pumped Ho:YLF lasers. For continuous wave (CW) operation, high pump intensity with small beam

  3. CO2 laser physics and tissue interactions in skin.

    Science.gov (United States)

    Fulton, J E; Shitabata, P K

    1999-01-01

    The theoretical model of CO2 laser tissue interaction appeared to be too simplistic. To explain the reactions seen in skin, a more complex model was needed. We hoped to correlate the clinical-histologic patterns of CO2 laser tissue interactions. The Ultrapulse CO2 laser was used on normal and pathologic skin conditions. Clinical observations were correlated with histologic examinations of biopsies. It was possible to demonstrate cavitation at the dermal-epidermal junction 2-3 diameters beyond the actual spot of CO2 laser contact with the skin. Dermal heat damage was seen as homogenization of collagen 1-2 diameters beyond the spot of laser contact. This flow of energy laterally at the dermal-epidermal junction and vertically down the skin follicles was both clinically beneficial and detrimental. Beneficially, superficial skin lesions separated at this junction and were easily removed. The heat coagulation of the dermis facilitated lesion removal without bleeding. The clinician had a better view of the pathology and could find focal zones of deeper pathology that could be easily re-treated. Detrimentally, this extended damage delayed wound healing and led to persistent erythema. These clinical-histologic correlations have provided a better understanding of CO2 laser tissue interactions in skin. It has been possible to take advantage of these findings to remove pathologic skin conditions more efficiently.

  4. Influence of acoustic waves on TEA CO 2 laser performance

    CSIR Research Space (South Africa)

    Von Bergmann, H

    2007-01-01

    Full Text Available In this paper the author’s present results on the influence of acoustic waves on the output laser beam from high repetition rate TEA CO 2 lasers. The authors show that acoustic waves generated inside the cavity lead to deterioration in beam quality...

  5. Interaction of CO2 laser radiation with dense plasma

    OpenAIRE

    Abdel-Raoof, Wasfi Sharkawy

    1980-01-01

    The instabilities which occur in the interaction of CO2 laser radiation with a dense plasma have been studied. A TEA CO2 laser provided pulses of up to 30 joules of energy with a duration of 50 nanoseconds. By focussing the radiation on to a plane target a focal spot of about 180 micrometers diameter was formed with a irradiance of 10 to 10 W cm. The scattered radiation was collected by a laser focussing lens and analysed with a grating spectrometer. Linear relationships have been found betwe...

  6. CO 2 lasers to destroy defiance of nanobacteria

    Directory of Open Access Journals (Sweden)

    Jafar Kolahi

    2015-01-01

    Full Text Available Introduction: Nanobacteria are mysterious particles that have spurred one of the biggest controversies in modern microbiology. The apatite mineral around the nanobacteria serves as a primary defense shield against various chemicals and extremely harsh condition. It is combined with a very slow metabolism of nanobacteria. These two items would be the likely explanation for the sever resistance of nanobacteria. The Hypothesis: The CO 2 laser is a continuous wave gas laser and emits infrared light at 9,600-10,600 nm in an easily manipulated focused beam that is well absorbed by water and hydroxyapatite. Hence, it seems logical to postulate that CO 2 laser can be used successfully to destroy defensive external hydroxyapatite layer of nanobacteria. Evaluation of the Hypothesis: Main criticism with this hypothesis is differential radiation of nanobacteria. It is well known that CO 2 laser has high water absorption and consequently can cause unwanted damage to human host tissues.

  7. A comparison of CO2 laser versus traditional stapedectomy outcomes.

    LENUS (Irish Health Repository)

    Ryan, S

    2012-02-01

    The aim of this study was to audit the introduction of the use of the CO2 laser into our department and to compare hearing outcomes and complication rates in patients who underwent either laser or mechanical stapedectomy. We found that the use of laser is at least as safe as the traditional approach with regards the rate of post-operative complications. One patient in the laser group suffered prolonged post-operative tinnitus, whilst one patient in the traditional group suffered prolonged post-operative vertigo. There was no evidence, however, of improved Air-Bone Gap closure compared to the traditional approach (Pre- and Post-Op Air Bone Gaps of 34 +\\/- 3 and 9 +\\/- 2 for laser stapedectomy versus 35 +\\/- 4 and 13 +\\/- 2 for traditional stapedectomy (mean +\\/- SEM)). In summary, therefore, CO2 laser surgery for otosclerosis is a safe surgical procedure resulting in similar hearing outcomes to that obtained following mechanical stapes surgery.

  8. Maximizing benefits and minimizing risk with CO2 laser resurfacing.

    Science.gov (United States)

    Fitzpatrick, Richard E

    2002-01-01

    Laser resurfacing using the high-energy, pulsed and scanned CO2 laser produces the most dramatic improvement in severe photo-induced facial rhytides and deeply atrophic scars. More recently, the use of short- and long-pulsed erbium lasers in conjunction with CO2 laser resurfacing has been shown to speed healing by removing the upper layer of thermally induced necrotic tissue. The Er:YAG lasers are more superficial ablative tools that inflict less residual thermal damage on the tissue, thus allowing healing to occur without the requisite internal clearance of excessive debris. With continued research and advances in laser surgery, cutaneous resurfacing will be further enhanced with improved outcomes and lessened morbidity.

  9. Defocused CO2 laser on equine skin: a histological examination.

    Science.gov (United States)

    Bergh, A; Ridderstråle, Y; Ekman, S

    2007-03-01

    No studies have been published on effects of treatment with a defocused beam carbon dioxide (CO2) laser on equine skin histology. A better understanding of this will help to define how lasers should be used, in order to reduce potential side effects. To describe the acute effects of different doses of defocused CO2 laser, ranging from therapeutic to surgical levels, on equine skin. Defocused CO2 laser was administered to the skin in the hamstrings (91 J/cm2), fetlock (137 J/cm2) and loin (450 J/cm2) areas of 13 Standardbred horses. The acute effects on skin histology were examined 90 min after the end of therapy. Mild changes with focal spongiosis and subepidermal clefts were found after 91 J/cm2 irradiation and more severe changes with diffuse subepidermal clefts after the 137 J/cm2 dose. A homogeneous eosinophilic acellular zone of dermis and destruction of adnexal structures, and significant thinning of the epidermis was observed after the 450 J/cm2 dose. The present study indicates acute dose-dependent changes in equine skin histology after laser treatment Severe tissue damage was induced using a 450 J/cm2 dose. To reduce the potential side effects of defocused CO2 laser treatment, the laser parameters must be carefully evaluated. Caution should be taken if doses higher than 91 J/cm2 (16 W, 4 min, and 42 cm2) are used in irradiation of equine skin.

  10. Optical Waveguide Structures for CO(2) Lasers.

    Science.gov (United States)

    Cheo, P K; Berak, J M; Oshinsky, W; Swindal, J L

    1973-03-01

    Thin-film waveguide structures consisting of epitaxially grown low-carrier-concentration GaAs and having two distinct index profiles have been investigated with a 10.6-microm C0(2) laser. Results of Schottky barrier and Hall measurements show that the carrier concentration of some of these films is less than 10(12) cm(-3), and the resistivity can be as high as 1.4 x 10(5) ?-cm. Guided-wave modes were excited by means of a germanium prism or phase grating coupler. When the index difference Deltan between the undoped film and the substrate is approximately 0.3 (strong guide), a number of modes can be obtained with a typical angular full width at half maximum intensity Delta(theta) (1/2) of coupler with a typical Deltatheta((1/2)) of approximately degrees . Measurements were also made of the transmission and cutoff characteristics of the TE and TM modes in weak guides as a function of the guide thickness that varied between 20 micro and 50 micro Results indicate that optical transmission decreases rapidly as the thickness of the weak guide decreases toward the cutoff value.

  11. Advances in CO2-Laser Drilling of Glass Substrates

    Science.gov (United States)

    Brusberg, Lars; Queisser, Marco; Gentsch, Clemens; Schröder, Henning; Lang, Klaus-Dieter

    The CO2 -laser drilling in Schott D263Teco thin glass having a thickness of 500 μm is intensively studied. The nearly cylindrical holes having diameters smaller 100 μm could be drilled in 0.25 seconds per hole. Reliability investigations by performing temperature cycling show cracks in 51% of the drilled holes in the glass substrate. The reason is thermally induced stress during thermal CO2 -laser ablation. Different thermal pre- and post-treatments have been successfully studied avoiding such cracks (98.4% crack-free holes) and show the high potential of CO2 -laser drilling for through glass via (TGV) processing in glass substrates for micro-system applications.

  12. CO2 lasers: beam patterns in relation to surgical use.

    Science.gov (United States)

    Fava, G; Emanuelli, H; Cascinelli, N; Bandieramonte, G; Canestri, F; Marchesini, R

    1983-01-01

    According to surgeons operating with a variety of CO2 lasers available at the National Cancer Institute of Milan (Coherent, Sharplan, Valfivre), these lasers have different cutting and coagulation properties. To identify what physical parameters might corroborate the subjective impression of the surgeons, a comparative study of the crater forms in perspex samples was performed. Perspex was chosen for its thermal properties (in fact, its thermal conductivity and diffusivity are similar to those of organic tissue) and because it allowed good visualization and measurement of crater characteristics. Depth of penetration, crater diameter, and extension of thermal damage were measured against power, focal length, and exposure time for each CO2 laser model. These results can be used as an index of behaviour of different surgical lasers. It appears that for fully characterizing the interaction of surgical lasers with the sample, it is necessary to specify either power, focal length, exposure time, or beam mode.

  13. Characterization of handpieces to control tissue ablation with pulsed CO2 laser

    Science.gov (United States)

    Verdaasdonck, Rudolf M.; van Swol, Christiaan F. P.; Coates, Judith

    1995-05-01

    Focusing handpieces used for CO2 beam delivery allow large variation of the power density in the spot depending on the distance to the tissue and hence the effect on the tissue. In contrast to the cw CO2 laser, the pulsed CO2 laser vaporized tissue water instantly (: equals ablation threshold), leaving a charless crater in the tissue surface. Only if the fluence is below or near threshold, the tissue effects are comparable with the cw laser. The threshold and tissue effects were studied for focusing (f equals 119 mm) and collimating (3 mm) handpieces coupled to an ultrapulsed CO2 laser. Using a special thermal imaging setup based on Schlieren techniques, the ablation threshold was determined depending on spotsize and pulse energy (1-200 mJ). In the focus of the handpiece, the threshold was already exceeded at 1 mJ, creating holes that were larger than the theoretical expected spotsize. The ablation threshold (J/cm2) increased for larger spotsizes. Below threshold, there is heating of the tissue resulting in coagulation. Above threshold, the exploding water vapor consumed thermal energy suppressing heating of the surrounding tissue. The gaussian shape of the collimated beam results in relatively more thermal effects. Focusing handpieces provide a wide range in power density and thus require experience from the surgeon. Collimated handpieces might be more easy to handle but offer less flexibility in tissue effect and a larger thermal zone.

  14. Material Processing with High Power CO2-Lasers

    Science.gov (United States)

    Bakowsky, Lothar

    1986-10-01

    After a period of research and development lasertechnique now is regarded as an important instrument for flexible, economic and fully automatic manufacturing. Especially cutting of flat metal sheets with high power C02-lasers and CNC controlled two or three axes handling systems is a wide spread. application. Three dimensional laser cutting, laser-welding and -heat treatment are just at the be ginning of industrial use in production lines. The main. advantages of laser technology. are - high. accuracy - high, processing velocity - law thermal distortion. - no tool abrasion. The market for laser material processing systems had 1985 a volume of 300 Mio S with growth rates between, 20 % and 30 %. The topic of this lecture are hiTrh. power CO2-lasers. Besides this systems two others are used as machining tools, Nd-YAG- and Eximer lasers. All applications of high. power CO2-lasers to industrial material processing show that high processing velocity and quality are only guaranteed in case of a stable intensity. profile on the workpiece. This is only achieved by laser systems without any power and mode fluctuations and by handling systems of high accuracy. Two applications in the automotive industry are described, below as examples for laser cutting and laser welding of special cylindrical motor parts.

  15. Improvement of dermatochalasis and periorbital rhytides with a high-energy pulsed CO2 laser: a retrospective study.

    Science.gov (United States)

    Alster, Tina S; Bellew, Supriya G

    2004-04-01

    Upper eyelid dermatochalasis is typically treated with excisional blepharoplasty. The role of the CO2 laser previously had been confined to that of a vaporizing, incisional, or hemostatic tool. Over the past several years, however, ablative CO2 laser skin resurfacing has been popularized as an adjunctive treatment to blepharoplasty to minimize periorbital rhytides through its vaporizing as well as skin-tightening action. To evaluate the safety and efficacy of a high-energy pulsed CO2 laser as a stand-alone treatment for dermatochalasis and periorbital rhytides. Sixty-seven patients (skin phototypes I-IV) with mild-to-severe upper eyelid dermatochalasis and periorbital rhytides received periocular CO2 laser skin treatment. Global assessment scores of dermatochalasis and rhytides were determined by a side-by-side comparison of periocular photographs preoperatively and 1, 3, and 6 months postoperatively. In addition, caliper measurements of upper eyelids before and 1, 3, and 6 months after treatment were obtained. Both dermatochalasis and periorbital rhytides were significantly improved after periocular CO2 laser skin resurfacing. Patients with more severe dermatochalasis and rhytides showed greater improvement after CO2 laser treatment than did those with mild or moderate involvement. Side effects were limited to erythema and transient hyperpigmentation. No scarring, hypopigmentation, or ectropion were observed. Periocular skin resurfacing with a CO2 laser can safely and effectively improve upper eyelid dermatochalasis and periorbital rhytides.

  16. Fractional CO(2) laser-assisted drug delivery

    DEFF Research Database (Denmark)

    Haedersdal, Merete; Sakamoto, Fernanda H; Farinelli, William A

    2010-01-01

    Ablative fractional resurfacing (AFR) creates vertical channels that might assist the delivery of topically applied drugs into skin. The purpose of this study was to evaluate drug delivery by CO(2) laser AFR using methyl 5-aminolevulinate (MAL), a porphyrin precursor, as a test drug.......Ablative fractional resurfacing (AFR) creates vertical channels that might assist the delivery of topically applied drugs into skin. The purpose of this study was to evaluate drug delivery by CO(2) laser AFR using methyl 5-aminolevulinate (MAL), a porphyrin precursor, as a test drug....

  17. CO2 - Laser Intestinal Anastomosis Histological And Manometric Study

    Science.gov (United States)

    Rabau, Micha Y.; Goldman, Gideon; Bar-Nea, Lilian; Wiznitzer, Theodor; Rochkind, Semion

    1988-06-01

    Low energy CO2 laser was used to perform intestinal anastomosis by means of tissue welding in 10 Wistar rats. The post operative course in the studied animals was uneventful. The integrity of the anastomosis was investigated manometrically, immediately upon completion of the anasto-mosis and twenty days later. Ten Wistar rats served as control in which conventional interrupted one-layer anastomosis was performed. The results show a significant superior-ity (Phistological examinations up to 90 days following surgery revealed complete healing and epithelialization of the anastomotic site. The technical details of the CO2 laser anastomosis are described.

  18. Investigation of damage to metals by pulsed CO2 laser radiation

    Science.gov (United States)

    Vedenov, A. A.; Gladush, G. G.; Drobyazko, S. V.; Senatorov, Yu M.

    1981-10-01

    A study was made of the physical mechanism involved in piercing holes in metallic plates, using CO2 laser radiation. It was established experimentally that the energy consumed in removing a unit volume of a metal has a minimum, depending on the duration and energy of the laser pulse. An explanation is proposed for the laws governing this behavior, based on ideas of the ejection of liquid from a crater by the vapor pressure of the material. The effect on the interaction efficiency of the absorption of laser radiation in the plasma jet is taken into account.

  19. Effect of Defocused CO2 Laser on Equine Tissue Perfusion

    Directory of Open Access Journals (Sweden)

    Bergh A

    2006-03-01

    Full Text Available Treatment with defocused CO2 laser can have a therapeutic effect on equine injuries, but the mechanisms involved are unclear. A recent study has shown that laser causes an increase in equine superficial tissue temperature, which may result in an increase in blood perfusion and a stimulating effect on tissue regeneration. However, no studies have described the effects on equine tissue perfusion. The aim of the present study was to investigate the effect of defocused CO2 laser on blood perfusion and to correlate it with temperature in skin and underlying muscle in anaesthetized horses. Differences between clipped and unclipped haircoat were also assessed. Eight horses and two controls received CO2 laser treatment (91 J/cm2 in a randomised order, on a clipped and unclipped area of the hamstring muscles, respectively. The significant increase in clipped skin perfusion and temperature was on average 146.3 ± 33.4 perfusion units (334% and 5.5 ± 1.5°C, respectively. The significant increase in perfusion and temperature in unclipped skin were 80.6 ± 20.4 perfusion units (264% and 4.8 ± 1.4°C. No significant changes were seen in muscle perfusion or temperature. In conclusion, treatment with defocused CO2 laser causes a significant increase in skin perfusion, which is correlated to an increase in skin temperature.

  20. Effects of a superpulsed CO2 laser on human teeth

    Science.gov (United States)

    Murgo, Dirian O. A.; Cerruti, Blanche; Redigolo, Marcela L.; Chavantes, Maria C.

    2001-10-01

    The effects of laser exposure on mineralized tissues like enamel have been explored for years as a technique to remove caries and for dental hard-tissue preparation. However the efficiency of this technique has been questioned. In this work, six freshly-extracted third molars were irradiated by a superpulse of CO2 laser, generally used in Transmyocardio Revascularization, and submitted to Scanning Electron Microscopy (SEM) analyzes. The cavities caused by laser irradiation on the dental tissues were analyzed considering its shape and depth. The CO2 superpulse presented a high efficiency in the removal of dental mass and no sign of carbonized tissue was found on the ablated surface. All cavities generated by laser irradiation presented a conic shape with average depth depending on energy density applied.

  1. Nonlinear Interaction of Transversal Modes in a CO2 Laser

    OpenAIRE

    Lopez-Ruiz, Ricardo; Mindlin, G. B.; Perez-Garcia, C.; Tredicce, J. R.

    2002-01-01

    We show the possibility of achieving experimentally a Takens-Bogdanov bifurcation for the nonlinear interaction of two transverse modes ($l = \\pm 1$) in a $CO_2$ laser. The system has a basic O(2) symmetry which is perturbed by some symmetry-breaking effects that still preserve the $Z_2$ symmetry. The pattern dynamics near this codimension two bifurcation under such symmetries is described. This dynamics changes drastically when the laser properties are modified.

  2. Fractional CO(2) laser-assisted drug delivery

    DEFF Research Database (Denmark)

    Haedersdal, Merete; Sakamoto, Fernanda H; Farinelli, William A

    2010-01-01

    Ablative fractional resurfacing (AFR) creates vertical channels that might assist the delivery of topically applied drugs into skin. The purpose of this study was to evaluate drug delivery by CO(2) laser AFR using methyl 5-aminolevulinate (MAL), a porphyrin precursor, as a test drug....

  3. Using a CO2 laser for PIR-detector spoofing

    NARCIS (Netherlands)

    Schleijpen, R.; Putten, F.J.M. van

    2016-01-01

    This paper presents experimental work on the use of a CO2 laser for triggering of PIR sensors. Pyro-electric InfraRed sensors are often used as motion detectors for detection of moving persons or objects that are warmer than their environment. Apart from uses in the civilian domain, also

  4. Efficient TEA CO 2 laser based coating removal system

    CSIR Research Space (South Africa)

    Prinsloo, FJ

    2007-04-01

    Full Text Available A high power 1kW pulsed transversely excited atmospheric CO 2 laser that has been developed for the paint stripping of missiles was used to test paint stripping on several metallic and composite aircraft panels to determine the rate at which...

  5. Absorption Enhanced Liquid Ablation with TEA CO2 Laser

    National Research Council Canada - National Science Library

    Sterling, Enrique

    2004-01-01

    ... that strongly absorbs radiation in the 8-11 m wavelength interval. A TEA CO2 laser (λ = 10.6 m), 300 ns pulse width and 8 J pulse energy, was used for ablation of water diluted NaBF4 contained in a conical aluminum nozzle...

  6. Lithiasis of salivary glands treated with a CO2 laser

    Science.gov (United States)

    Grzesiak-Janas, Grazyna; Janas, Anna

    2003-10-01

    The study compares the results of classical surgical treatment with laserotherapy in lithiasis of submandibular salivary glands. The study included 48 patients, 26 of which were treated with application of a CO2 laser. The follow-up did not reveal any postoperative complications in the course of healing. No relapse of the disease was observed in patients.

  7. Computer modeling of pulsed CO2 lasers for lidar applications

    Science.gov (United States)

    Spiers, Gary D.

    1993-01-01

    The object of this effort is to develop code to enable the accurate prediction of the performance of pulsed transversely excited (TE) CO2 lasers prior to their construction. This is of particular benefit to the NASA Laser Atmospheric Wind Sounder (LAWS) project. A benefit of the completed code is that although developed specifically for the pulsed CO2 laser much of the code can be modified to model other laser systems of interest to the lidar community. A Boltzmann equation solver has been developed which enables the electron excitation rates for the vibrational levels of CO2 and N2, together with the electron ionization and attachment coefficients to be determined for any CO2 laser gas mixture consisting of a combination of CO2, N2, CO, He and CO. The validity of the model has been verified by comparison with published material. The results from the Boltzmann equation solver have been used as input to the laser kinetics code which is currently under development. A numerical code to model the laser induced medium perturbation (LIMP) arising from the relaxation of the lower laser level has been developed and used to determine the effect of LIMP on the frequency spectrum of the LAWS laser output pulse. The enclosed figures show representative results for a laser operating at 0.5 atm. with a discharge cross-section of 4.5 cm to produce a 20 J pulse with aFWHM of 3.1 microns. The first four plots show the temporal evolution of the laser pulse power, energy evolution, LIMP frequency chirp and electric field magnitude. The electric field magnitude is taken by beating the calculated complex electric field and beating it with a local oscillator signal. The remaining two figures show the power spectrum and energy distribution in the pulse as a function of the varying pulse frequency. The LIMP theory has been compared with experimental data from the NOAA Windvan Lidar and has been found to be in good agreement.

  8. Polycarbonate resin drilling by longitudinally excited CO2 laser

    Science.gov (United States)

    Uno, Kazuyuki; Kato, Masaya; Akitsu, Tetsuya; Jitsuno, Takahisa

    2017-02-01

    We developed a longitudinally excited CO2 laser with a long external cavity and investigated the drilling characteristics of polycarbonate resin. The CO2 laser was very simple and consisted of a 45-cm-long alumina ceramic pipe with an inner diameter of 13 mm, a pulse power supply, a step-up transformer, a storage capacitance, and a long external optical cavity with a cavity length of 175 cm and an aperture of 9 mm. The CO2 laser produced a short pulse that had a spike pulse with the width of 282 ns and the energy of 0.45 mJ, a pulse tail with the length of 66.9 μs and the energy of 15.65 mJ, and a good circular beam. In a processing system, a ZnSe focusing lens with the focal length of 50 mm was used and the location of the focal plane was that of the sample surface. In the drilling of polycarbonate resin by the CO2 laser, the drilling characteristics depended on the number of pulses and the fluence was investigated. Clear drilling without carbonization was produced by the irradiation of 50 pulses or less with the fluence of 19 J/cm2 and the irradiation of 100 pulses or less with the fluence of 8 J/cm2. The clear drilling with the deepest depth in this work was 403 μm at the 50 pulses irradiation with the fluence of 19 J/cm2. The number of pulses and the fluence can control thermal influence in the CO2 laser processing of polycarbonate resin.

  9. Dental hard tissue drilling by longitudinally excited CO2 laser

    Science.gov (United States)

    Uno, Kazuyuki; Yamamoto, Takuya; Akitsu, Tetsuya; Jitsuno, Takahisa

    2017-07-01

    We developed a longitudinally excited CO2 laser with a long optical cavity and investigated the drilling characteristics of dental hard tissue. The CO2 laser was very simple and consisted of a 45-cm-long alumina ceramic pipe with an inner diameter of 13 mm, a pulse power supply, a step-up transformer, a storage capacitance, a spark gap, and a long optical cavity with a cavity length of 175 cm. The CO2 laser produced a short pulse that had a spike pulse with the width of 337 ns and the energy of 1.9 mJ, a pulse tail with the length of 180 μs and the energy of 37.6 mJ, and a doughnut-like beam. In the investigation, a sample was a natural drying human tooth (enamel and dentine). In a processing system, a ZnSe focusing lens with the focal length of 50 mm was used and the location of the focal plane was that of the sample surface. In 1 pulse irradiation, the drilling characteristics depended on the fluence was investigated. In the enamel and dentin drilling, the drilling depth increased with the fluence. The 1 pulse irradiation with the fluence of 21.5 J/cm2 produced the depth of 79.3 μm in the enamel drilling, and the depth of 152.7 μm in the dentin drilling. The short-pulse CO2 laser produced a deeper drilling depth at a lower fluence than long-pulse CO2 lasers in dental hard tissue processing.

  10. Monte-Carlo based Uncertainty Analysis For CO2 Laser Microchanneling Model

    Science.gov (United States)

    Prakash, Shashi; Kumar, Nitish; Kumar, Subrata

    2016-09-01

    CO2 laser microchanneling has emerged as a potential technique for the fabrication of microfluidic devices on PMMA (Poly-methyl-meth-acrylate). PMMA directly vaporizes when subjected to high intensity focused CO2 laser beam. This process results in clean cut and acceptable surface finish on microchannel walls. Overall, CO2 laser microchanneling process is cost effective and easy to implement. While fabricating microchannels on PMMA using a CO2 laser, the maximum depth of the fabricated microchannel is the key feature. There are few analytical models available to predict the maximum depth of the microchannels and cut channel profile on PMMA substrate using a CO2 laser. These models depend upon the values of thermophysical properties of PMMA and laser beam parameters. There are a number of variants of transparent PMMA available in the market with different values of thermophysical properties. Therefore, for applying such analytical models, the values of these thermophysical properties are required to be known exactly. Although, the values of laser beam parameters are readily available, extensive experiments are required to be conducted to determine the value of thermophysical properties of PMMA. The unavailability of exact values of these property parameters restrict the proper control over the microchannel dimension for given power and scanning speed of the laser beam. In order to have dimensional control over the maximum depth of fabricated microchannels, it is necessary to have an idea of uncertainty associated with the predicted microchannel depth. In this research work, the uncertainty associated with the maximum depth dimension has been determined using Monte Carlo method (MCM). The propagation of uncertainty with different power and scanning speed has been predicted. The relative impact of each thermophysical property has been determined using sensitivity analysis.

  11. Atmospheric remote sensing via optically pumped CO2 laser

    Science.gov (United States)

    Shutov, Anton; Shutova, Mariia; Goltsov, Alexander; Sokolov, Alexei; Scully, Marlan

    2017-04-01

    With the growing global warming problem atmospheric remote sensing, especially remote detection of CO2 levels, has become a hot topic nowadays. Here we discuss an idea on how CO2 gas in air can be turned into a laser medium. This type of CO2 laser is pumped via Raman vibrational mode excitation of the nitrogen present in air. We propose an experiment to implement this type of a laser, where vibrational excitation of nitrogen is produced by a pair of Raman-resonant laser pulses. We quantify the efficiency of the Raman excitation process by observing cascaded Raman sideband generation. When excitation of the first vibrational state takes place in some portion of nitrogen molecules, it is accompanied by generation of multiple Stokes and anti-Stokes sideband. Following the excitation of the vibrations in nitrogen, carbon dioxide molecules become excited due to collisions and lasing takes place as in a conventional carbon dioxide laser. The work is funded by:NSF(PHY1307153,CHE1609608),Office of Naval Research(Award N00014-16-1-3054,N00014-16-1-2578),Robert A.Welch Foundation(Grant A-1261,A-1547).AS,MS thank the Herman F.Heep and Minnie Belle Heep TAMU Endowed Fund held by the TAMU Found.

  12. The use of laser CO2 in salivary gland diseases

    Science.gov (United States)

    Ciolfi, C.; Rocchetti, F.; Fioravanti, M.; Tenore, G.; Palaia, G.; Romeo, U.

    2016-03-01

    Salivary gland diseases can include reactive lesions, obstructive lesions, and benign tumors. All these clinical entities are slow growing. Salivary glands reactive lesions, such as mucoceles, can result from extravasation of saliva into the surrounding soft tissue or from retention of saliva within the duct. Sialolithiasis, one of the most common obstructive lesions, is generally due to calculi, which are attributed to retention of saliva. Monomorphic adenoma is a salivary gland benign tumor, which is exclusively resulted from proliferation of epithelial cells, with no alterations interesting the connective tissue. The elective therapy of these lesions is surgical excision because sometimes they can be accompained by difficulties during chewing and phonation and can interfere with prosthesis's stability. The aim of the study is to evaluate the efficacy of CO2 laser in the treatment of patients with salivary gland diseases. Three different cases - a mucocele, a scialolithiasis and a monomorphic adenoma - were treated with CO2 laser excision (CW and 4W), under local anesthesia. Two different techniques were used: circumferential incision for the adenoma, and mucosa preservation technique for mucocele and sialolithiasis. In each case final haemostasis was obtained by thermocoagulation, but suture was applied to guarantee good healing by sewing up the flaps. The patients were checked after twenty days and the healing was good. The carbon dioxide laser (CO2 laser) was one of the earliest gas laser to be developed, and is still the highest-power continuous wave laser that is currently available. In dentistry the CO2 laser produces a beam of infrared light with the principal wavelength bands centering around 9.4 and 10.6 micrometers. Laser excision can be very useful in oral surgery. In the cases presented CO2 laser offered, differently from traditional surgery, simplified surgical technique, shorter duration of operation, minimal postoperative pain, minimal scarring

  13. TEA CO2 laser machining of CFRP composite

    Science.gov (United States)

    Salama, A.; Li, L.; Mativenga, P.; Whitehead, D.

    2016-05-01

    Carbon fibre-reinforced polymer (CFRP) composites have found wide applications in the aerospace, marine, sports and automotive industries owing to their lightweight and acceptable mechanical properties compared to the commonly used metallic materials. Machining of CFRP composites using lasers can be challenging due to inhomogeneity in the material properties and structures, which can lead to thermal damages during laser processing. In the previous studies, Nd:YAG, diode-pumped solid-state, CO2 (continuous wave), disc and fibre lasers were used in cutting CFRP composites and the control of damages such as the size of heat-affected zones (HAZs) remains a challenge. In this paper, a short-pulsed (8 μs) transversely excited atmospheric pressure CO2 laser was used, for the first time, to machine CFRP composites. The laser has high peak powers (up to 250 kW) and excellent absorption by both the carbon fibre and the epoxy binder. Design of experiment and statistical modelling, based on response surface methodology, was used to understand the interactions between the process parameters such as laser fluence, repetition rate and cutting speed and their effects on the cut quality characteristics including size of HAZ, machining depth and material removal rate (MRR). Based on this study, process parameter optimization was carried out to minimize the HAZ and maximize the MRR. A discussion is given on the potential applications and comparisons to other lasers in machining CFRP.

  14. Laser surgery in otolaryngology: interaction of CO2 laser and soft tissue.

    Science.gov (United States)

    Mihashi, S; Jako, G J; Incze, J; Strong, M S; Vaughan, C W

    1976-01-30

    The sequence of histological change induced by CO2 laser irradiation was discussed in terms of two factors: the physiomechanical factor and the physiochemical factor. At sufficiently high heat energy levels, the immediate findings are characterized by crater formation resulting from rapid vaporization of the water and ejection of the solid component. In the immediate vicinity of the crater edge, the maximum tissue temperature rise is 65 degrees C above the 32 degrees C ambient tissue temperature and it decreases to the primary tissue temperature within a distance of 2 mm. The healing process of CO2 laser induced lesions proceeds with minimal delay. The lymphatic and vascular channels are occluded in the marginal area of coagulation resulting in a marked hemostatic effect. This sealing effect increases the margin of safety in preventing possible dissemination of tumor cells. By selecting the appropriate power, time, and focus cone angle, precise destruction of preselected areas of tissue can be achieved with an extraordinary hemostatic effect without damaging the underlying tissue. These advantages are especially helpful in function-preserving surgery.

  15. Laser Sounder for Global Measurement of CO2 Concentrations in the Troposphere from Space: Progress

    Science.gov (United States)

    Abshire, J. B.; Krainak, M.; Riris, H. J.; Sun, X.; Riris, H.; Andrews, A. E.; Collatz, J.

    2004-01-01

    We describe progress toward developing a laser-based technique for the remote measurement of the tropospheric CO2 concentrations from orbit. Our goal is to demonstrate a lidar technique and instrument technology that will permit measurements of the CO2 column abundance in the lower troposphere from aircraft at the few ppm level, with a capability of scaling to permit global CO2 measurements from orbit. Accurate measurements of the tropospheric CO2 mixing ratio from space are challenging due to the many potential error sources. These include possible interference from other trace gas species, the effects of temperature, clouds, aerosols & turbulence in the path, changes in surface reflectivity, and variability in dry air density caused by changes in atmospheric pressure, water vapor and topographic height. Some potential instrumental errors include frequency drifts in the transmitter, small transmission and sensitivity drifts in the instrument. High signal-to-noise ratios and measurement stability are needed for mixing ratio estimates at the few ppm level. We have been developing a laser sounder approach as a candidate for a future space mission. It utilizes multiple different laser transmitters to permit simultaneous measurement of CO2 and O2 extinction, and aerosol backscatter in the same measurement path. It directs the narrow co-aligned laser beams from the instrument's fiber lasers toward nadir, and measures the energy of the strong laser echoes reflected from the Earth's land and water surfaces. During the measurement its narrow linewidth lasers are rapidly tuned on- and off- selected CO2 line near 1572 nm and an O2 absorption line near 770 nm. The receiver measures the energies of the laser echoes from the surface and any clouds and aerosols in the path with photon counting detectors. Ratioing the on- to off-line echo pulse energies for each gas permits the column extinction and column densities of CO2 and O2 to be estimated simultaneously via the

  16. Spectrally Tailored Pulsed Thulium Fiber Laser System for Broadband Lidar CO2 Sensing

    Science.gov (United States)

    Heaps, William S.; Georgieva, Elena M.; McComb, Timothy S.; Cheung, Eric C.; Hassell, Frank R.; Baldauf, Brian K.

    2011-01-01

    Thulium doped pulsed fiber lasers are capable of meeting the spectral, temporal, efficiency, size and weight demands of defense and civil applications for pulsed lasers in the eye-safe spectral regime due to inherent mechanical stability, compact "all-fiber" master oscillator power amplifier (MOPA) architectures, high beam quality and efficiency. Thulium fiber's longer operating wavelength allows use of larger fiber cores without compromising beam quality, increasing potential single aperture pulse energies. Applications of these lasers include eye-safe laser ranging, frequency conversion to longer or shorter wavelengths for IR countermeasures and sensing applications with otherwise tough to achieve wavelengths and detection of atmospheric species including CO2 and water vapor. Performance of a portable thulium fiber laser system developed for CO2 sensing via a broadband lidar technique with an etalon based sensor will be discussed. The fielded laser operates with approximately 280 J pulse energy in 90-150ns pulses over a tunable 110nm spectral range and has a uniquely tailored broadband spectral output allowing the sensing of multiple CO2 lines simultaneously, simplifying future potentially space based CO2 sensing instruments by reducing the number and complexity of lasers required to carry out high precision sensing missions. Power scaling and future "all fiber" system configurations for a number of ranging, sensing, countermeasures and other yet to be defined applications by use of flexible spectral and temporal performance master oscillators will be discussed. The compact, low mass, robust, efficient and readily power scalable nature of "all-fiber" thulium lasers makes them ideal candidates for use in future space based sensing applications.

  17. Pattern dynamics in an annular CO2 laser

    OpenAIRE

    Ramon, M.L. (M. L.); Meucci, R. (R.); Allaria, E.; Boccaletti, S.

    2000-01-01

    Competition among modes in an annular CO2 laser has been experimentally and numerically analyzed. During the coexistence of di erent patterns, each of them resulting from the interaction of two transverse modes with opposite angular momentum, chaos has been experimentally detected. A numerical model, derived from the Maxwell-Bloch equations and including symmetry breaking terms, enables the interpretation of the main experimental features.

  18. Treatment of acne scarring with fractional CO2 laser.

    Science.gov (United States)

    Qian, Hui; Lu, Zhong; Ding, Huilin; Yan, Shuxian; Xiang, Leihong; Gold, Michael H

    2012-08-01

    Fractional ablative CO(2) laser therapy is based on the theory of fractional photothermolysis. It can be effective in treating acne scars in a less invasive fashion than conventional ablative CO(2) laser therapy. In this clinical study, the safety and efficacy of a novel CO(2) fractional ablative laser was investigated for the treatment of facial atrophic acne scarring in Chinese individuals. A total of 31 patients (11 females, 20 males, Fitzpatrick skin phototypes III-IV) with facial acne scarring received three sequential fractional treatments over a 6-month period. Outcome measurements included blinded evaluations of before and after photographs by two physicians at 3 and 12 months after the final treatment. Global improvement was noted as well as any untoward events. At the 12 months follow-up time period, 12.9% of the patients showed excellent improvement in their acne scars, while 38.71% noted good to fair results. The clinical response at the 12-month follow-up visit tended to be better than at the 3-month follow-up visit, but was not statistically significant. Four patients experienced post-treatment and transient PIH but three patients were noted to have prolonged erythema. There was no evidence hypopigmentation or worsening of the scarring in any of the study patients. This high-energy pulsed and cool-scanned fractional ablative CO(2) laser system is safe and effective for facial atrophic acne scarring. Improvement in scarring was noted in the majority of patients with minimal discomfort and minimal downtime. Continued improvement over time is also an important clinical finding.

  19. Parametric study of intersatellite CO2 laser data links

    Science.gov (United States)

    Bonek, E.; Lutz, H.

    The performance capability of current CO2 laser communication tecnology for intersatellite data links is evaluated. The link parameters, such as the distance, bit rate, ac signal-to-noise ratio, are related to the masses and the prime power requirements of satellite laser terminals using variables like the telescope (antenna) aperture diameter and the transmitted laser power. It is found that high data rates could be readily transmitted with telescopes of the order of only 10 cm in diameter, with the complte laser data terminals weighing between 25 kg and 70 kg and consuming prime power in the 90-300 W range. In addition, these terminals would require only about 0.1 cu m or less of volume and a very low movable antenna mass, which would alleviate constraints on satellite attitude control units in remote sensing missions.

  20. Towards absolute laser spectroscopic CO2 isotope ratio measurements

    Science.gov (United States)

    Anyangwe Nwaboh, Javis; Werhahn, Olav; Ebert, Volker

    2017-04-01

    Knowledge of isotope composition of carbon dioxide (CO2) in the atmosphere is necessary to identify sources and sinks of this key greenhouse gas. In the last years, laser spectroscopic techniques such as cavity ring-down spectroscopy (CRDS) and tunable diode laser absorption spectroscopy (TDLAS) have been shown to perform accurate isotope ratio measurements for CO2 and other gases like water vapour (H2O) [1,2]. Typically, isotope ratios are reported in literature referring to reference materials provided by e.g. the International Atomic Energy Agency (IAEA). However, there could be some benefit if field deployable absolute isotope ratio measurement methods were developed to address issues such as exhausted reference material like the Pee Dee Belemnite (PDB) standard. Absolute isotope ratio measurements would be particularly important for situations where reference materials do not even exist. Here, we present CRDS and TDLAS-based absolute isotope ratios (13C/12C ) in atmospheric CO2. We demonstrate the capabilities of the used methods by measuring CO2 isotope ratios in gas standards. We compare our results to values reported for the isotope certified gas standards. Guide to the expression of uncertainty in measurement (GUM) compliant uncertainty budgets on the CRDS and TDLAS absolute isotope ratio measurements are presented, and traceability is addressed. We outline the current impediments in realizing high accuracy absolute isotope ratio measurements using laser spectroscopic methods, propose solutions and the way forward. Acknowledgement Parts of this work have been carried out within the European Metrology Research Programme (EMRP) ENV52 project-HIGHGAS. The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union. References [1] B. Kühnreich, S. Wagner, J. C. Habig,·O. Möhler, H. Saathoff, V. Ebert, Appl. Phys. B 119:177-187 (2015). [2] E. Kerstel, L. Gianfrani, Appl. Phys. B 92, 439-449 (2008).

  1. CO2 laser-driven Stirling engine. [space power applications

    Science.gov (United States)

    Lee, G.; Perry, R. L.; Carney, B.

    1978-01-01

    A 100-W Beale free-piston Stirling engine was powered remotely by a CO2 laser for long periods of time. The engine ran on both continuous-wave and pulse laser input. The working fluid was helium doped with small quantities of sulfur hexafluoride, SF6. The CO2 radiation was absorbed by the vibrational modes of the sulfur hexafluoride, which in turn transferred the energy to the helium to drive the engine. Electrical energy was obtained from a linear alternator attached to the piston of the engine. Engine pressures, volumes, and temperatures were measured to determine engine performance. It was found that the pulse radiation mode was more efficient than the continuous-wave mode. An analysis of the engine heat consumption indicated that heat losses around the cylinder and the window used to transmit the beam into the engine accounted for nearly half the energy input. The overall efficiency, that is, electrical output to laser input, was approximately 0.75%. However, this experiment was not designed for high efficiency but only to demonstrate the concept of a laser-driven engine. Based on this experiment, the engine could be modified to achieve efficiencies of perhaps 25-30%.

  2. Subsurface plasma in beam of continuous CO2-laser

    Science.gov (United States)

    Danytsikov, Y. V.; Dymshakov, V. A.; Lebedev, F. V.; Pismennyy, V. D.; Ryazanov, A. V.

    1986-03-01

    Experiments performed at the Institute of Atomic Energy established the conditions for formation of subsurface plasma in substances by laser radiation and its characteristics. A quasi-continuous CO2 laser emitting square pulses of 0.1 to 1.0 ms duration and 1 to 10 kW power as well as a continuous CO2 laser served as radiation sources. Radiation was focused on spots 0.1 to 0.5 mm in diameter and maintained at levels ensuring constant power density during the interaction time, while the temperature of the target surface was measured continuously. Metals, graphite and dielectric materials were tested with laser action taking place in air N2 + O2 mixtures, Ar or He atmosphere under pressures of 0.01 to 1.0 atm. Data on radiation intensity thresholds for evaporation and plasma formation were obtained. On the basis of these thresholds, combined with data on energy balance and the temperature profile in plasma layers, a universal state diagram was constructed for subsurface plasma with nonquantified surface temperature and radiation intensity coordinates.

  3. Simulation Studies of Satellite Laser CO2 Mission Concepts

    Science.gov (United States)

    Kawa, Stephan Randy; Mao, J.; Abshire, J. B.; Collatz, G. J.; Sun X.; Weaver, C. J.

    2011-01-01

    Results of mission simulation studies are presented for a laser-based atmospheric CO2 sounder. The simulations are based on real-time carbon cycle process modeling and data analysis. The mission concept corresponds to ASCENDS as recommended by the US National Academy of Sciences Decadal Survey. Compared to passive sensors, active (lidar) sensing of CO2 from space has several potentially significant advantages that hold promise to advance CO2 measurement capability in the next decade. Although the precision and accuracy requirements remain at unprecedented levels of stringency, analysis of possible instrument technology indicates that such sensors are more than feasible. Radiative transfer model calculations, an instrument model with representative errors, and a simple retrieval approach complete the cycle from "nature" run to "pseudodata" CO2. Several mission and instrument configuration options are examined, and the sensitivity to key design variables is shown. Examples are also shown of how the resulting pseudo-measurements might be used to address key carbon cycle science questions.

  4. Progress Toward Measuring CO2 Isotopologue Fluxes in situ with the LLNL Miniature, Laser-based CO2 Sensor

    Science.gov (United States)

    Osuna, J. L.; Bora, M.; Bond, T.

    2015-12-01

    One method to constrain photosynthesis and respiration independently at the ecosystem scale is to measure the fluxes of CO2­ isotopologues. Instrumentation is currently available to makes these measurements but they are generally costly, large, bench-top instruments. Here, we present progress toward developing a laser-based sensor that can be deployed directly to a canopy to passively measure CO2 isotopologue fluxes. In this study, we perform initial proof-of-concept and sensor characterization tests in the laboratory and in the field to demonstrate performance of the Lawrence Livermore National Laboratory (LLNL) tunable diode laser flux sensor. The results shown herein demonstrate measurement of bulk CO2 as a first step toward achieving flux measurements of CO2 isotopologues. The sensor uses a Vertical Cavity Surface Emitting Laser (VCSEL) in the 2012 nm range. The laser is mounted in a multi-pass White Cell. In order to amplify the absorption signal of CO2 in this range we employ wave modulation spectroscopy, introducing an alternating current (AC) bias component where f is the frequency of modulation on the laser drive current in addition to the direct current (DC) emission scanning component. We observed a strong linear relationship (r2 = 0.998 and r2 = 0.978 at all and low CO2 concentrations, respectively) between the 2f signal and the CO2 concentration in the cell across the range of CO2 concentrations relevant for flux measurements. We use this calibration to interpret CO2 concentration of a gas flowing through the White cell in the laboratory and deployed over a grassy field. We will discuss sensor performance in the lab and in situ as well as address steps toward achieving canopy-deployed, passive measurements of CO2 isotopologue fluxes. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-675788

  5. Symptomatic hemangioma of oral cavity treated with CO2 laser

    Science.gov (United States)

    Nicola, Ester M. D.; Coutinho, Adriana A.; Nicola, Jorge H.; Gusmao, Reinaldo J.

    1995-05-01

    The CO2 laser has been used by our group as a secure and efficient tool for the treatment of symptomatic oral cavity hemangiomas which can be responsible for disturbance for swallowing, phonation and in hygienic, besides discomfort and bleeding to patients. During the last four years, twelve patients with symptomatic oral cavity hemangioma were treated at the Laser Unit of our University. The treatment consisted in the application of CO2 laser at medium to low intensity according to characteristics and location of the lesions. For hemangiomas located at sites of easy surgical access such as anterior 1/3 of the tongue, lips, bucal vestibule we use 10 to 37 J/mm2 over the surface of the lesion. When the hemangioma was located at difficult surgical access sites, such as, tonsils, posterior 1/3 of tongue, or at pharyngeal wall we used 3.0 to 4.0 J/mm2 encircling the whole hemangioma. This causes reduction in the size of the lesion throughout sclerosis of nutrition vessels. After this initial procedure we applied 0.8 to 1.0 J/mm2 over the whole extent of the lesion. For both procedures we observed no significant bleeding or inflammatory reaction. The patients referred minimal post-operative discomfort with good cicatricial evolution. The evident reduction in the vascularization and size could be confirmed by photographic documentation. The good results described above, with disappearance of symptoms lead to the conclusion that CO2 laser is an efficient and secure method of treatment for symptomatic hemangioma of the oral cavity.

  6. Combined Treatment Of Purulent Wounds With CO2 Laser

    Science.gov (United States)

    Tolstych, P. I.; Skobelkin, O. K.; Derbenev, V. A.

    1988-06-01

    The authors have worked out a programme for combined treatment of purulent wounds with CO2 laser. It consists of following components: a) laserinsision of suppurative wounds,necrectomy,or irradiation of the incised wound with the defocused laser beam; b )diplication of proteinerses and antiseptics immobilized on the textile dressing and dranaige materials; c) applications of biocompatible materials with the immobilized antiseptics and enzyme agents; d) application of low energy laser irradiation in the postoperative period; e) lavage of the sutured wound if indicated. The points of the above-mentioned programme can be used separately as independed methods in several thousands of patients. Their combined applications has been studied on 400 patients. Such treatment allowed to refuse the antibioticotherapy in 98,3% of cases,to reduce the terms of trestment in I,5-2 % times as compared with traditional methods, and to low significantely costs.

  7. Analysis, simulation, and experimental studies of YAG and CO2 laser-produced plasma for EUV lithography sources

    Science.gov (United States)

    Hassanein, A.; Sizyuk, V.; Harilal, S. S.; Sizyuk, T.

    2010-04-01

    Efficient laser systems are essential for the realization of high volume manufacturing in extreme ultraviolet lithography (EUVL). Solid-state Nd:YAG lasers usually have lower efficiency and source suppliers are alternatively investigating the use of high power CO2 laser systems. However, CO2 laser-produced plasmas (LPP) have specific characteristics and features that should be taken into account when considering them as the light source for EUVL. The analysis of recent experimental and theoretical work showed significant differences in the properties of plasma plumes produced by CO2 and the Nd:YAG lasers including EUV radiation emission, source formation, debris generation, and conversion efficiency. The much higher reflectivity of CO2 laser from liquid, vapor, and plasma of a tin target results in the production of optically thinner plumes with higher velocity and in a better formation of plasma properties (temperature and density values) towards more efficient EUV source. However, the spikes in the temporal profiles of current CO2 laser will additionally affect the properties of the produced plasma. We have developed unique combination of state-of-the-art experimental facilities (CMUXE Laboratory) and advanced computer simulation (HEIGHTS) package for studying and optimizing various lasers, discharge produced plasmas (DPP), and target parameters as well as the optical collection system regarding EUV lithography. In this work, detailed characteristics of plasmas produced by CO2 and Nd:YAG lasers were analyzed and compared both experimentally and theoretically for optimizing EUV from LPP sources. The details of lower overheating of plasma produced by CO2 laser are given with time and explain how to utilize the high reflectivity of such lasers in plasmas produced in different target geometries to significantly enhance the conversion efficiency of EUV radiation.

  8. Laser-assisted hair transplantation: histologic comparison between holmium:YAG and CO2 lasers

    Science.gov (United States)

    Chu, Eugene A.; Rabinov, C. Rose; Wong, Brian J.; Krugman, Mark E.

    1999-06-01

    The histological effects of flash-scanned CO2 (λ=10.6μm) and pulsed Holmium:YAG (Ho:YAG, λ=2.12μm) lasers were evaluated in human scalp following the creation of hair transplant recipient channels. Ho:YAG laser irradiation created larger zones of thermal injury adjacent to the laser channels than irradiation with the CO2 laser device. When the two lasers created recipient sites of nearly equal depth, the Holmium:YAG laser caused a larger region of lateral thermal damage (589.30μm) than the CO2 laser (118.07μm). In addition, Holmium:YAG irradiated specimens exhibited fractures or discontinuities beyond the region of clear thermal injury. This shearing effect is consistent with the photoacoustic mechanism of ablation associated with pulsed mid-IR laser irradiation. In contrast, channels created with the CO2 exhibited minimal epithelial disruption and significantly less lateral thermal damage. While the Holmium:YAG laser is a useful tool for ablation soft tissue with minimal char in select applications (sinus surgery, arthroscopic surgery), this study suggests that the use of the CO2 laser for the creation of transplantation recipient channels result in significantly less lateral thermal injury for the laser parameters employed.

  9. Chemical vapor deposition on chabazite (CHA) zeolite membranes for effective post-combustion CO2 capture.

    Science.gov (United States)

    Kim, Eunjoo; Lee, Taehee; Kim, Hyungmin; Jung, Won-Jin; Han, Doug-Young; Baik, Hionsuck; Choi, Nakwon; Choi, Jungkyu

    2014-12-16

    Chabazite (CHA) zeolites with a pore size of 0.37 × 0.42 nm(2) are expected to separate CO2 (0.33 nm) from larger N2 (0.364 nm) in postcombustion flue gases by recognizing their minute size differences. Furthermore, the hydrophobic siliceous constituent in CHA membranes can allow for maintaining the CO2/N2 separation performance in the presence of H2O in contrast with the CO2 affinity-based membranes. In an attempt to increase the molecular sieving ability, the pore mouth size of all silica CHA (Si-CHA) particles was reduced via the chemical vapor deposition (CVD) of a silica precursor (tetraethyl orthosilicate). Accordingly, an increase of the CVD treatment duration decreased the penetration rate of CO2 into the CVD-treated Si-CHA particles. Furthermore, the CVD process was applied to siliceous CHA membranes in order to improve their CO2/N2 separation performance. Compared to the intact CHA membranes, the CO2/N2 maximum separation factor (max SF) for CVD-treated CHA membranes was increased by ∼ 2 fold under dry conditions. More desirably, the CO2/N2 max SF was increased by ∼ 3 fold under wet conditions at ∼ 50 °C, a representative temperature of the flue gas stream. In fact, the presence of H2O in the feed disfavored the permeation of N2 more than that of CO2 through CVD-modified CHA membranes and thus, contributed to the increased CO2/N2 separation factor.

  10. Laser spectrometer for CO2 clumped isotope analysis

    Science.gov (United States)

    Prokhorov, Ivan; Kluge, Tobias; Janssen, Christof

    2017-04-01

    Carbon dioxide clumped isotope thermometry has proven to be a reliable method for biogeochemical and atmospheric research. We present a new laser spectroscopic instrument for doubly-substituted isotopologues analysis. In contrast to a conventional isotope ratio mass spectrometry (IRMS), tunable laser direct absorption spectroscopy (TLDAS) has the advantage of isotopologue-specific determination free of isobaric interferences. Tunable infrared laser based spectrometer for clumped isotope analysis is being developed in collaboration between Heidelberg University, Germany, and LERMA-IPSL, CNRS, France. The instrument employs two continuous intraband cascade lasers (ICL) tuned at 4439 and 4329 nm. The spectral windows covered by the lasers contain absorption lines of the six most abundant CO2 isotopologues, including the two doubly substituted species 16O13C18O and 16O13C17O, and all singly substituted isotopologues with 13C, 18O and 17O. A Herriott-type multi-pass cell provides two different absorption pathlengths to compensate the abundance difference between singly- and doubly-substituted isotopologues. We have reached the sub-permill precision required for clumped isotope measurements within the integration time of several seconds. The test version of the instrument demonstrates a performance comparable to state of the art IRMS. We highlight the following features of the instrument that are strong advantages compared to conventional mass spectrometry: measurement cycle in the minute range, simplified sample preparation routine, table-top layout with a potential for in-situ applications.

  11. Low density, non-ablative fractional CO2 laser rejuvenation.

    Science.gov (United States)

    Christiansen, Kaare; Bjerring, Peter

    2008-09-01

    Fractional skin rejuvenation has gained increased interest since its introduction in 2003. Both non-ablative and ablative lasers as well as different treatment techniques have been devised. Recent clinical studies indicate that a paradigm of low spot density combined with high fluences tend to produce better clinical results and less risk of post-inflammatory hyperpigmentation in darker skin types. The present study is focused on investigations of the clinical outcome by non-ablative fractional CO(2) treatments with a single pass with low spot density. A CO(2) laser was equipped with a scanner enabling it to perform fractional treatments with 36, 64 or 100 microthermal zones (MTZ)/cm(2). Twelve patients participated in the study. The perioral area was treated three times with 1-month intervals using a spot density of 64 MTZ/cm(2), a spot diameter of 0.5 mm, a micro-beam energy of 36-60 mJ, and a pulse duration of 3-5 milliseconds. Follow-up was performed 3 months after the last treatment. At the 3-month follow-up 72.7% of the volunteers had obtained improvement in ultrasonographically determined dermal density, and the average improvement was 40.2% (SD: 48.0%). This improvement was statistically significant (Plaser treatments.

  12. Technology of discharge and laser resonators for high power CO2 lasers. Koshutsuryoku CO2 laser ni tsukawareru hoden reiki laser kyoshinki gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    Takenaka, Y.; Kuzumoto, M. (Mitsubishi Electric Corp., Tokyo (Japan))

    1994-03-20

    This paper describes discharge excitation technology and resonator technology as basic technologies for high power CO2 lasers. As a result of progress in high-frequency power element techniques, the discharge excitation technology now generally uses laser excitation using AC discharge of capacity coupling type. Its representative example is silent discharge (SD) excitation. This is a system to excite laser by applying high voltages with as high frequency as 100 kHz to 1 MHz across a pair of electrodes covered with a dielectric material. The system maintains stability in discharge even if power supply voltage amplitude is modulated, and easily provides pulse outputs. Discharge excitation for diffusion cooled type CO2 laser generates a discharge in a gap with a gap length of about 2 mm, and can perform gas cooling by means of thermal conduction of gas, whereas a compact resonator can be fabricated. A resonator for the diffusion cooled type CO2 laser eliminates gas circulation and cooling systems, hence the device can be made more compact. A report has been given that several of these compact resonators were combined, from which a laser output of 85W was obtained by using RF discharge of 2kW. 43 refs., 21 figs.

  13. Ablation of Liquids for Laser Propulsion with TEA CO2 Laser

    National Research Council Canada - National Science Library

    Sinko, John; Kodgis, Lisa; Porter, Simon; Sterling, Enrique; Lin, Jun; Pakhomov, Andrew V; Larson, C. W; Mead, Jr, Franklin B

    2005-01-01

    .... A Transversely Excited at Atmospheric pressure (TEA) CO2 laser operated at 10.6 micro-m, 300 ns pulse width, and 9 J pulse energy was used to ablate liquids contained in various aluminum and glass vessels...

  14. Ablation of Liquids for Laser Propulsion With TEA CO2 Laser

    National Research Council Canada - National Science Library

    Sinko, John; Kodgis, Lisa; Porter, Simon; Sterling, Enrique; Lin, Jun; Pakhomov, Andrew V; Larson, C. W; Mead, Jr., Franklin B

    2005-01-01

    .... A Transversely Excited at Atmospheric pressure (TEA) CO2 laser operated at 10.6 um, 300 ns pulse width, and 9 J pulse energy was used to ablate liquids contained in various aluminum and glass vessels...

  15. Tunable diode laser measurements of hydrothermal/volcanic CO2 and implications for the global CO2 budget

    Science.gov (United States)

    Pedone, M.; Aiuppa, A.; Giudice, G.; Grassa, F.; Francofonte, V.; Bergsson, B.; Ilyinskaya, E.

    2014-12-01

    Quantifying the CO2 flux sustained by low-temperature fumarolic fields in hydrothermal/volcanic environments has remained a challenge, to date. Here, we explored the potential of a commercial infrared tunable laser unit for quantifying such fumarolic volcanic/hydrothermal CO2 fluxes. Our field tests were conducted between April 2013 and March 2014 at Nea Kameni (Santorini, Greece), Hekla and Krýsuvík (Iceland) and Vulcano (Aeolian Islands, Italy). At these sites, the tunable laser was used to measure the path-integrated CO2 mixing ratios along cross sections of the fumaroles' atmospheric plumes. By using a tomographic post-processing routine, we then obtained, for each manifestation, the contour maps of CO2 mixing ratios in the plumes and, from their integration, the CO2 fluxes. The calculated CO2 fluxes range from low (5.7 ± 0.9 t d-1; Krýsuvík) to moderate (524 ± 108 t d-1; La Fossa crater, Vulcano). Overall, we suggest that the cumulative CO2 contribution from weakly degassing volcanoes in the hydrothermal stage of activity may be significant at the global scale.

  16. A comparative evaluation: Oral leukoplakia surgical management using diode laser, CO2 laser, and cryosurgery.

    Science.gov (United States)

    Natekar, Madhukar; Raghuveer, Hosahallli-Puttaiah; Rayapati, Dilip-Kumar; Shobha, Eshwara-Singh; Prashanth, Nagesh-Tavane; Rangan, Vinod; Panicker, Archana G

    2017-06-01

    The comparatively evaluate the three surgical treatment modalities namely cryosurgery, diode and CO2 laser surgery in terms of healing outcomes on the day of surgery, first and second week post operatively and recurrence at the end of 18 months was assessed. Thirty selected patients were divided randomly into three groups. Each group comprising of ten patients were subjected to one of the three modalities of treatment namely cryosurgery, diode laser or CO2 laser surgery for ablation of OL. Obtained data was analyzed using mainly using Chi-square and Anova tests. Study showed statistical significant differences (p > 0.05) for evaluation parameters like pain, edema and scar. The parameters like infection, recurrence, bleeding showed no statistical significance. Pain was significantly higher in CO2 laser surgery group as compared with diode laser group. There was no recurrence observed at the end of the 6 months follow up period in all the three study groups. Observations from the study highlights that all three surgical modalities used in this study were effective for treatment of OL, and the overall summation of the results of the study showed that laser therapy (CO2 and Diode) seems to offer better clinically significant results than cryotherapy. Key words:Oral premalignant lesion, leukoplakia, cryosurgery, CO2 laser surgery, diode laser surgery.

  17. [Dissertations 25 years after date 29. CO2 laser surgery of leukoplakia of the oral mucosa].

    Science.gov (United States)

    Roodenburg, J L N

    2011-10-01

    With a CO2 laser superficial lesions of the oral mucosa can be removed by evaporation. During CO2 laser evaporation there is minimal damage to the surrounding tissue, resulting in minimal scarring after healing. Therefore the CO2 laser seems to be a modality which is appropriate for the treatment of leukoplakia of the oral mucosa. In 1985, the effect of CO2 laser light on mucosa and the healing after CO2 laser evaporation was studied. In addition, clinical research was carried out concerning the effectiveness of CO2 laser evaporation in the treatment of 103 cases of leukoplakia of the oral mucosa The cure-rate was 91% and no malignant degenerations were seen in the treated area. The group was expanded (282) and evaluated again, with a cure-rate of 90%. In 1% of the cases, malignant degenerations were seen. CO2 laser evaporation seems the modality of choice for the treatment of leukoplakia of the oral mucosa.

  18. CO2 Laser Cutting of Hot Stamping Boron Steel Sheets

    Directory of Open Access Journals (Sweden)

    Pasquale Russo Spena

    2017-10-01

    Full Text Available This study investigates the quality of CO2 laser cutting of hot stamping boron steel sheets that are employed in the fabrication of automotive body-in-white. For this purpose, experimental laser cutting tests were conducted on 1.2 mm sheets at varying levels of laser power, cutting speed, and oxygen pressure. The resulting quality of cut edges was evaluated in terms of perpendicularity tolerance, surface irregularity, kerf width, heat affected zone, and dross extension. Experimental tests were based on a L9(34 orthogonal array design, with the effects of the process parameters on the quality responses being determined by means of a statistical analysis of variance (ANOVA. Quadratic mathematical models were developed to determine the relationships between the cutting parameters and the quality responses. Finally, a routine based on an optimization criterion was employed to predict the optimal setting of cutting factors and its effect on the quality responses. A confirmation experiment was conducted to verify the appropriateness of the optimization routine. The results show that all of the examined process parameters have a key role in determining the cut quality of hot stamping boron steel sheets, with cutting speed and their interactions having the most influencing effects. Particularly, interactions can have an opposite behavior for different levels of the process parameters.

  19. Use of CO2 laser as an adjunctive treatment for caudal stomatitis in a cat.

    Science.gov (United States)

    Lewis, John R; Tsugawa, Anson J; Reiter, Alexander M

    2007-12-01

    Lasers have become a popular tool in veterinary practice, particularly the carbon dioxide (CO2) laser. In humans, the CO2 laser is used most commonly in oral and maxillofacial soft tissue surgery due to its favorable interactions with oral soft tissues. Other types of lasers are better suited for use on hard tissues such as enamel and dentin. This article reviews the history of laser use, physics of laser-tissue interaction, delivery systems, and laser types used in dentistry and oral surgery. This is followed by a case report describing the use of CO2 laser as an adjunctive treatment for therapy of refractory caudal stomatitis in a cat.

  20. Tumor surgery with the CO2 laser studies with the cloudman S91 mouse melanoma.

    NARCIS (Netherlands)

    Oosterhuis, Jan Wolter

    1977-01-01

    In this thesis investigations into iatrogenic tumor spread by the CO2 Iaser are reported. The continuous wave CO2 laser has some properties making it attractive to tumor surgery. No-touch removal of even bone-hard tissues is possible. The CO2 laser incision is relatively bloodless. Endoscopic

  1. Interaction of cw CO2 laser radiation with plasma near-metallic substrate surface

    Science.gov (United States)

    Azharonok, V. V.; Astapchik, S. A.; Zabelin, Alexandre M.; Golubev, Vladimir S.; Golubev, V. S.; Grezev, A. N.; Filatov, Igor V.; Chubrik, N. I.; Shimanovich, V. D.

    2000-07-01

    Optical and spectroscopic methods were used in studying near-surface plasma that is formed under the effect CW CO2 laser of (2- 5)x106W/cm2 power density upon stainless steel in He and Ar shielding gases. The variation of plume spatial structure with time has been studied, the outflow of gas-vapor jets from the interaction area has been characterized. The spectra of plasma plume pulsations have been obtained for the frequency range Δf = 0-1 MHz. The temperature and electron concentration of plasma plume have been found under radiation effect upon the target of stainless steel. Consideration has been given to the most probable mechanisms of CW laser radiation-metal non-stationary interaction.

  2. Differential absorption lidar CO2 laser system for remote sensing of TATP related gases.

    Science.gov (United States)

    Pal, Avishekh; Clark, C Douglas; Sigman, Michael; Killinger, Dennis K

    2009-02-01

    A CW tunable 10.6 microm CO(2) laser differential absorption lidar (DIAL) system has been developed, for the first time to our knowledge, for the remote sensing of triacetone triperoxide (TATP) gas vapors, which have strong absorption lines at several wavelengths, including 3.3, 8.3, and 10.6 microm. The DIAL laser beam was transmitted through an enclosed absorption cell containing TATP or SF(6), and backscattered returns were measured from a retroreflector array target at ranges of 5-100 m. DIAL sensitivity for the detection of TATP was about 0.5 ng/microl [52 parts in 10(6)(ppm)] for a 0.3 m path.

  3. Laser Doppler velocimetry based on the optoacoustic effect in a RF-excited CO2 laser.

    Science.gov (United States)

    Lee, Teaghee; Choi, Jong Woon; Kim, Yong Pyung

    2012-09-01

    We present a compact optoacoustic laser Doppler velocimetry method that utilizes the self-mixing effect in a RF-excited CO(2) laser. A portion of a Doppler-shifted laser beam, produced by irradiating a single wavelength laser beam on a moving object, is mixed with an originally existing laser beam inside a laser cavity. The fine change of pressure in the laser cavity modulated by the Doppler-shifted frequency is detected by a condenser microphone in the laser tube. In our studies, the frequency of the Doppler signal due to the optoacoustic effect was detected as high as 50 kHz. Our measurements also confirmed that the signal varied linearly with the velocity of the external scatterer (the moving object) and the cosine of the angle between the laser beam and the velocity vector of the object.

  4. Liquid-vapor equilibrium of the systems butylmethylimidazolium nitrate-CO2 and hydroxypropylmethylimidazolium nitrate-CO2 at high pressure: influence of water on the phase behavior.

    Science.gov (United States)

    Bermejo, M Dolores; Montero, Marta; Saez, Elisa; Florusse, Louw J; Kotlewska, Aleksandra J; Cocero, M José; van Rantwijk, Fred; Peters, Cor J

    2008-10-30

    Ionic liquids (IL) are receiving increasing attention due to their potential as "green" solvents, especially when used in combination with SC-CO2. In this work liquid-vapor equilibria of binary mixtures of CO2 with two imidazolium-based ionic liquids (IL) with a nitrate anion have been experimentally determined: butylmethylimidazolium nitrate (BMImNO3) and hydroxypropylmethylimidazolium nitrate (HOPMImNO3), using a Cailletet apparatus that operates according to the synthetic method. CO2 concentrations from 5 up to 30 mol % were investigated. It was found that CO2 is substantially less soluble in HOPMImNO3 than in BMImNO3. Since these ILs are very hygroscopic, water easily can be a major contaminant, causing changes in the phase behavior. In case these Ils are to be used in practical applications, for instance, together with CO2 as a medium in supercritical enzymatic reactions, it is very important to have quantitative information on how the water content will affect the phase behavior. This work presents the first systematic study on the influence of water on the solubility of carbon dioxide in hygroscopic ILs. It was observed that the presence of water reduces the absolute solubility of CO2. However, at fixed ratios of CO2/IL, the bubble point pressure remains almost unchanged with increasing water content. In order to explain the experimental results, the densities of aqueous mixtures of both ILs were determined experimentally and the excess molar volumes calculated.

  5. Effect of argon on the performance of a fast-axial flow CO2 laser

    Science.gov (United States)

    Jelvani, S.; Amiri, Kh; Pazokian, H.; Montazerolghaem, M.; Mollabashi, M.; Naeimi, S. A.; Esmaeilpour, D.

    2011-01-01

    The performance characteristics of a fast-axial flow (FAF) cw CO2 laser are described. The dependences of the output power, efficiency, and discharge voltage on the discharge current of a FAF cw CO2 laser with optimised composition of the CO2:N2:He=1:4.4:7.6 gas mixture with a small amount of argon are studied experimentally at two pressures of 50 and 60 mbar in open and closed cycle regimes of the laser system.

  6. On the correlation of water vapor and CO2: Application to flux partitioning of evapotranspiration

    Science.gov (United States)

    Wang, Wen; Smith, James A.; Ramamurthy, Prathap; Baeck, Mary Lynn; Bou-Zeid, Elie; Scanlon, Todd M.

    2016-12-01

    The partitioning of evapotranspiration (ET) between plant transpiration (Et) and direct evaporation (Ed) presents one of the most important and challenging problems for characterizing ecohydrological processes. The exchange of water vapor (q) and CO2 (c) are closely coupled in ecosystem processes and knowledge of their controls can be gained through joint investigation of q and c. In this study we examine the correlation of water vapor and CO2 (Rqc) through analyses of high-frequency time series derived from eddy covariance measurements collected over a suburban grass field in Princeton, NJ during a 2 year period (2011-2013). Rqc at the study site exhibits pronounced seasonal and diurnal cycles, with maximum anticorrelation in June and maximum decorrelation in January. The diurnal cycle of Rqc varies seasonally and is characterized by a near-symmetric shape with peak anticorrelation around local noon. Wavelet and spectral analyses suggest that q and c are jointly transported for most eddy scales (1-200 m), which is important for ET partitioning methods based on flux variance similarity. The diurnal cycle of the transpiration fraction (ratio of Et to total ET) exhibits an asymmetric diurnal cycle, especially during the warm season, with peak values occurring in the afternoon. These ET partitioning results give similar diurnal and seasonal patterns compared with numerical simulations from the Noah Land Surface Model using the Jarvis canopy resistance formulation.

  7. Surgical CO2 Laser Units With Specialized Beam-Delivery Systems

    Science.gov (United States)

    Artjushenko, Vjacheslav G.; Danila, Leon; Dianov, Evgeni M.; Dumitras, Dan C.; Dutu, Doru C.; Konov, Vitaly I.; Nikiforov, Sergey M.; Prokhorov, Alexander M.; Saker, H.; Sargin, M. M.; Ursu, Ioan

    1989-09-01

    The continuous expanding of CO2 laser applications in medicine needs not only compact, reliable and multifunctional surgical CO2 laser units, but also specialized beam delivery systems, which are essential to extend the clinical use of lasers. Our effort for improving the surgical CO2 laser units was directed to : a) developing compact CO2 laser scalpels, reliable and more suitable for the surgical operating theatre by using high performance with low maintenance average power sealed-off CO2 lasers; b) designing specialized electronic circuits to increase the protection degree against uncontrolled irradiation by technical failures or wrong manipulation; c) extending the operating regimes, i.e. continuous wave, laser pulses with pre-established length and laser pulses with variable repetition frequency. The beam delivery systems used with our surgical CO2 lasers units included opto-mechanical articulated arms, IR fiber optic cables and laser microscope adaptors. Coupling different CO2 laser scalpels, beam delivery systems and terminals, we have tested these surgical laser units in neurosurgery, otolaryngology,,ophthalmology and microvascular lympho-venous anastomosis. The most significant data recorded by us on the interaction of laser radiation with living matter are shortly reviewed.

  8. Effectiveness of CO2 laser with subcision in patients with acne scars.

    Science.gov (United States)

    Anupama, Y G; Wahab, Afthab Jameela

    2016-11-01

    Post-acne facial scarring has always been a challenge to treat. It requires multiple therapeutic modalities as single modality is not hundred percent effective. Therefore, we have combined CO2 laser resurfacing with subcision in patients with acne scars for better results. The aim is to study the effectiveness and side effects of CO2 laser with subcision in patients with atrophic acne scars. Fifty patients were selected for the study. Baseline grading was done with Goodman and Baron grading system. Twenty-five patients were randomly selected for subcision followed by CO2 laser and the remaining patients were selected for CO2 laser alone. The treatment was done for four sessions at 4-week interval. Clinical photographs were obtained for evaluation. CO2 laser with subcision showed excellent response in grade-2 and -3 acne scars. Statistically there is a significant difference between CO2 laser following subcision and CO2 laser alone at 5% level (p acne scars. Subcision prior to the CO2 laser procedure showed better improvement when compared to CO2 laser alone. Thus, in acne scars, multiple therapeutic modalities achieve better results.

  9. Tunable CO2 laser system with subnanosecond-pulse-train output

    Science.gov (United States)

    Kimura, W. D.

    2017-02-01

    A CO2 laser system has been demonstrated that generates a train of subnanosecond pulses tunable over the P and R branches of the CO2 laser spectrum at 9-11 μm. It utilizes optical free induction decay to generate a single 100-ps laser pulse from a tunable transverse-excited-atmospheric CO2 laser. This laser pulse is injection-seeded into a high-pressure CO2 oscillator whose output consists of a train of amplified 100-ps pulses with maximum pulse energy of 30 mJ, corresponding to a peak power of 300 MW. The 100-ps, tunable, infrared laser pulses are needed for a new technique to remotely detect atmospheric gaseous molecules, which relies on the train of CO2 laser pulses selectively exciting the target molecules whose presence is then revealed using a separate terahertz probe beam.

  10. The treatment of oral leukoplakia with the CO2 laser: A retrospective study of 65 patients.

    Science.gov (United States)

    Mogedas-Vegara, Alfonso; Hueto-Madrid, Juan-Antonio; Chimenos-Küstner, Eduardo; Bescós-Atín, Coro

    2015-06-01

    The use of CO2 laser has become a routine procedure for the treatment of oral leukoplakia. In this retrospective study, we evaluated 65 patients with oral leukoplakia treated with CO2 laser vaporization. The main location was the tongue (n = 21/65, 32.3%). The initial biopsy showed mild/moderate dysplasia in almost half the patients (n = 29, 44.6%) and hyperplasia without dysplasia in around a third of the patients (n = 21, 32.3%). The recurrence and malignant transformation rates were 33.8% (n = 22) and 15.4% (n = 10), respectively. The follow-up mean (standard deviation) was 15.0 (10.6) months. The procedure-related complications rate was 7.7% (n = 5). The Kaplan-Meier curves for time to recurrence showed differences only for gingiva lesions compared to tongue lesions (log rank, p = 0.032). Malignant leukoplakia transformation is independent of treatment, although it seems advisable to treat leukoplakia with or without dysplasia. Copyright © 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

  11. Comparative study of CO2- and Er:YAG laser ablation of multiple cutaneous neurofibromas in von Recklinghausen's disease.

    Science.gov (United States)

    Kriechbaumer, Lukas K; Susani, Martin; Kircher, Susanne G; Distelmaier, Klaus; Happak, Wolfgang

    2014-05-01

    With a prevalence of 1 in 3,000 births, neurofibromatosis type 1 (NF1) is one of the most common genetic disorders and is characterized by an uninhibited expansion of neural tissue. Occasionally, severe deformities occur, but frequently considerable cosmetic disfigurement is caused by the development of hundreds of benign cutaneous neurofibromas. The objective of this study was to evaluate the erbium:yttrium-aluminium-garnet (Er:YAG) laser as a therapeutic option for the removal of multiple cutaneous neurofibromas. In this prospective, comparative, in vivo study, 15,580 neurofibromas (44 operations on 21 patients) were removed via electrosurgery, CO2- or Er:YAG laser ablation. In 12 adjacent test areas, we compared the zone of thermal necrosis, the postoperative pain, the time to reepithelialization, the duration of postoperative erythema and the cosmetic outcome of these surgical methods. When compared to electrosurgery and CO2 laser ablation, the Er:YAG laser ablation outperformed the other methods of tumor removal. Rapid healing by second intention as well as the minimal discomfort and scar formation following Er:YAG laser ablation were noted. After 36 months of follow-up, permanent dyspigmentation was rare and hypertrophic scarring was not observed. Er:YAG laser vaporization of multiple cutaneous neurofibromas is a simple and rapid procedure that results in significantly better cosmetic results than CO2 laser treatment or electrosurgery.

  12. Comparison of wound healing using the CO2 laser at 10.6 microm and 9.55 microm.

    Science.gov (United States)

    Converse, G M; Ries, W R; Reinisch, L

    2001-07-01

    The wound healing characteristics of incisions made with the short pulsed CO2 laser tuned to 9.55 microm versus the traditional 10.6 microm were investigated. Previous studies have shown that at 9.55 microm, collagen is targeted more selectively than at 10.6 microm, which results in decreased acute thermal injury patterns. This study investigates the difference in wound healing over time between lasers and compares laser incisions with cold knife techniques. Randomized controlled trial using a porcine model. Tissue from 10.6-microm and 9.55-microm incisions of 10 piglets was evaluated with histological analysis and tensiometry at 3, 7, 14, and 21 days postoperatively. A Bonferroni-Dunn corrected analysis of variance analysis at a 95% significance level was used to compare the effect of wavelength. The results demonstrate that although knife incisions are consistently stronger than laser incisions, the 9.55-microm CO2 laser incisions are no stronger than incisions made with the conventional 10.6-microm laser. Furthermore, histological analysis shows no difference in lateral thermal damage between lasers at 3, 7, 14, and 21 days postoperatively. The progression of collagen formation and inflammation does not differ over time. This study of wound healing using a porcine model demonstrates that the 9.55-microm CO2 laser does not demonstrate an improvement in wound healing over the traditional 10.6-microm CO2 laser. These results may be secondary to the common explosive vaporization mechanism produced by both lasers in the infrared spectrum.

  13. Selection of Near Optimal Laser Cutting Parameters in CO2 Laser Cutting by the Taguchi Method

    Directory of Open Access Journals (Sweden)

    Miloš MADIĆ

    2013-12-01

    Full Text Available Identification of laser cutting conditions that are insensitive to parameter variations and noise is of great importance. This paper demonstrates the application of Taguchi method for optimization of surface roughness in CO2 laser cutting of stainless steel. The laser cutting experiment was planned and conducted according to the Taguchi’s experimental design using the L27 orthogonal array. Four laser cutting parameters such as laser power, cutting speed, assist gas pressure, and focus position were considered in the experiment. Using the analysis of means and analysis of variance, the significant laser cutting parameters were identified, and subsequently the optimal combination of laser cutting parameter levels was determined. The results showed that the cutting speed is the most significant parameter affecting the surface roughness whereas the influence of the assist gas pressure can be neglected. It was observed, however, that interaction effects have predominant influence over the main effects on the surface roughness.

  14. The results of CO2 laser surgery in patients with oral leukoplakia : a 25 year follow

    NARCIS (Netherlands)

    van der Hem, PS; Nauta, JM; van der Wal, JE; Roodenburg, JLN

    Oral leukoplakia, is an important premalignant Lesion of the oral mucosa. We treat this Lesion prophylactically with CO2 laser evaporation. In the period from 1976 to 2001, a group of 200 patients with 282 oral leukoplakias were treated by CO2 laser evaporation. In a follow up period of 1-219 months

  15. Stabilization of an AM mode-locked tea CO2 laser

    NARCIS (Netherlands)

    van Goor, F.A.

    1983-01-01

    An increased shot-to-shot reproducibility has been obtained by injection of radiation from a cw CO2 laser in an amplitude mode-locked TEA CO2 laser without additional pulse broadening. Stable pulses variable from 900 ps up to 4 ns have been generated with this new technique.

  16. Hypertrophic scars after therapy with CO2 laser for treatment of multiple cutaneous neurofibromas

    NARCIS (Netherlands)

    J.U. Ostertag (Judith); C.C.W. Theunissen (Chantal); H.A.M. Neumann (Martino)

    2002-01-01

    textabstractBACKGROUND. CO2 laser surgery is a treatment modality for cutaneous neurofibromas. OBJECTIVE. Hypertrophic and atrophic scars can result from treatment with CO2 laser surgery. We present a case of cutaneous neurofibromatosis that developed hypertrophic scars postoperatively. METHODS.

  17. Reflection of Carbon Dioxide (CO 2 ) laser radiation from the theatre ...

    African Journals Online (AJOL)

    This work has investigated the power of both specular and diffusely reflected beams of CO2 laser radiation from metallic and non-metallic surfaces of an operating theatre including surgical instruments (specula) and different samples of wall paints in theatre 6 of the Aberdeen Royal Infirmary, U.K. where the CO2 laser ...

  18. A new approach to model CW CO2 laser using rate equations

    Indian Academy of Sciences (India)

    2016-11-11

    Nov 11, 2016 ... assumption of the different modes to be in thermal equilibrium. Moore et al [8] and Tychinskii [9] were the first to independently propose these rate equations for the CW CO2 laser. Tyte [10] used such a model to calculate population densities of the vibration lev- els of a CW CO2 laser, in the non-lasing case.

  19. Investigations in CO2 laser beam caustics measuring techniques

    DEFF Research Database (Denmark)

    Olsen, Flemming Ove; Bagger, Claus

    2004-01-01

    The performance of an industrial laser is very much depending upon the characteristics of the laser beam. The ISO standards 11146 and 11154 which are describing test methods for laser beam parameters have been approved.......The performance of an industrial laser is very much depending upon the characteristics of the laser beam. The ISO standards 11146 and 11154 which are describing test methods for laser beam parameters have been approved....

  20. Evaluation of catalyst for closed cycle operation of high energy pulsed CO2 lasers

    Science.gov (United States)

    Rogowski, R. S.; Miller, I. M.; Wood, G.; Schryer, D. R.; Hess, R. V.; Upchurch, B. T.

    1983-01-01

    Several catalyst materials have been tested for efficiency of converting CO and O2 to CO2 for use in a high energy CO2 laser. The composition of the gas mixtures was monitored by mass spectrometry and gas chromatography. A copper/copper oxide catalyst and a platinum/tin oxide catalyst were used for closed cycle operation of a CO2 laser (0.7 joules/pulse), operating at 10 pulses/sec.

  1. Comparison of Ultrasonic and CO2 Laser Pretreatment Methods on Enzyme Digestibility of Corn Stover

    Directory of Open Access Journals (Sweden)

    Li-Li Zuo

    2012-03-01

    Full Text Available To decrease the cost of bioethanol production, biomass recalcitrance needs to be overcome so that the conversion of biomass to bioethanol becomes more efficient. CO2 laser irradiation can disrupt the lignocellulosic physical structure and reduce the average size of fiber. Analyses with Fourier transform infrared spectroscopy, specific surface area, and the microstructure of corn stover were used to elucidate the enhancement mechanism of the pretreatment process by CO2 laser irradiation. The present work demonstrated that the CO2 laser had potential to enhance the bioconversion efficiency of lignocellulosic waste to renewable bioethanol. The saccharification rate of the CO2 laser pretreatment was significantly higher than ultrasonic pretreatment, and reached 27.75% which was 1.34-fold of that of ultrasonic pretreatment. The results showed the impact of CO2 laser pretreatment on corn stover to be more effective than ultrasonic pretreatment.

  2. Technology assessment of high pulse energy CO(2) lasers for remote sensing from satellites

    Science.gov (United States)

    Hess, R. V.; Brockman, P.; Schryer, D. R.; Miller, I. M.; Bair, C. H.; Sidney, B. D.; Wood, G. M.; Upchurch, B. T.; Brown, K. G.

    1985-01-01

    Developments and needs for research to extend the lifetime and optimize the configuration of CO2 laser systems for satellite based on remote sensing of atmospheric wind velocities and trace gases are reviewed. The CO2 laser systems for operational satellite application will require lifetimes which exceed 1 year. Progress in the development of efficient low temperature catalysts and gas mixture modifications for extending the lifetime of high pulse energy closed cycle common and rare isotope CO2 lasers and of sealed CW CO2 lasers is reviewed. Several CO2 laser configurations are under development to meet the requirements including: unstable resonators, master oscillator power amplifiers and telescopic stable resonators, using UV or E-beam preionization. Progress in the systems is reviewed and tradeoffs in the system parameters are discussed.

  3. High efficiency metal marking with CO2 laser and glass marking with excimer laser

    DEFF Research Database (Denmark)

    Bastue, Jens; Olsen, Flemmming Ove

    1997-01-01

    with a thoroughly tested ray-tracing model is presented and compared with experimental results. Special emphasis is put on two different applications namely marking in metal with TEA-CO2 laser and marking in glass with excimer laser. The results are evaluated on the basis of the achievable energy enhancement......Today, mask based laser materials processing and especially marking is widely used. However, the energy efficiency in such processes is very low [1].This paper gives a review of the results, that may be obtained using the energy enhancing technique [1]. Results of simulations performed...

  4. Performance of density functionals for modeling vapor liquid equilibria of CO2 and SO2.

    Science.gov (United States)

    Goel, Himanshu; Windom, Zachary W; Jackson, Amber A; Rai, Neeraj

    2017-11-21

    Vapor liquid equilibria (VLE) and condensed phase properties of carbon dioxide and sulfur dioxide are calculated using first principles Monte Carlo (FPMC) simulations to assess the performance of several density functionals, notably PBE-D3, BLYP-D3, PBE0-D3, M062X-D3, and rVV10. GGA functionals were used to compute complete vapor liquid coexistence curves (VLCCs) to estimate critical properties, while the hybrid and nonlocal van der Waals functionals were used only for computing density at a single state point due to the high computational cost. Our results show that the BLYP-D3 functional performs well in predicting VLE properties for both molecules when compared with other functionals. In the liquid phase, pair correlation functions reveal that there is not a significant difference in the location of the peak for the first solvation shell while the peak heights are different for different functionals. Overall, the BLYP-D3 functional is a good choice for modeling VLE of acidic gases with significant environmental implications such as CO2 and SO2 . © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  5. O uso do laser de CO2 na prevenção da carie dentaria

    OpenAIRE

    Lidiany Karla Azevedo Rodrigues

    2005-01-01

    Resumo: A irradiação do esmalte dental com laser de CO2, especialmente se associada ao flúor, aumenta a resistência deste substrato ao desafio ácido. Deste modo, esta tese, constituída por 3 artigos, teve por objetivos: (1) descrever as características do laser de CO2 e revisar a literatura disponível enfocando seus efeitos na prevenção de cárie em esmalte e dentina, bem como discutir os efeitos deste mesmo laser quando associado ao flúor; (2) investigar, in vitro, o efeito do laser de CO2 (?...

  6. Impact of two CO(2) laser heatings for damage repairing on fused silica surface.

    Science.gov (United States)

    Cormont, P; Gallais, L; Lamaignère, L; Rullier, J L; Combis, P; Hebert, D

    2010-12-06

    CO(2) laser is an interesting tool to repair defects on silica optics. We studied UV nanosecond laser-induced damage in fused silica after CO(2) laser heating. The localization of damage sites and the laser damage threshold are closely related to stress area in silica induced by heating. By applying a suitable second laser heating, we managed to eliminate the debris issued from redeposited silica and to modify the stress area. As a consequence, a significant increase of laser resistance has been observed. This process offers the possibility to improve damage repairing sufficiently to extend the lifetime of the silica components.

  7. LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Dynamics of splashing of molten metals during irradiation with single CO2 laser pulses

    Science.gov (United States)

    Arutyunyan, R. V.; Baranov, V. Yu; Bol'shov, Leonid A.; Dolgov, V. A.; Malyuta, D. D.; Mezhevov, V. S.; Semak, V. V.

    1988-03-01

    An experimental investigation was made of the dynamics of the loss of the melt as a result of interaction with single-mode CO2 laser radiation pulses of 5-35 μs duration. The dynamics of splashing of the melt during irradiation with short pulses characterized by a Gaussian intensity distribution differed from that predicted by models in which the distribution of the vapor pressure was assumed to be radially homogeneous.

  8. Highlights of Thirty-Year Experience of CO2 Laser Use at the Florence (Italy) Department of Dermatology

    Science.gov (United States)

    Campolmi, Piero; Bonan, Paolo; Cannarozzo, Giovanni; Bassi, Andrea; Bruscino, Nicola; Arunachalam, Meena; Troiano, Michela; Lotti, Torello; Moretti, Silvia

    2012-01-01

    The CO2 laser has been used extensively in dermatological surgery over the past 30 years and is now recognised as the gold standard for soft tissue vaporization. Considering that the continuous wave CO2 laser delivery system and the newer “superpulsed” and scanned CO2 systems have progressively changed our practice and patient satisfaction, a long range documentation can be useful. Our experience has demonstrated that the use of CO2 laser involves a reduced healing time, an infrequent need for anaesthesia, reduced thermal damage, less bleeding, less inflammation, the possibility of intra-operative histologic and/or cytologic examination, and easy access to anatomically difficult areas. Immediate side effects have been pain, erythema, edema, typically see with older methods, using higher power. The percentage of after-treatment keloids and hypertrophic scars observed was very low (~1%) especially upon the usage of lower parameters. The recurrence of viral lesions (condylomas and warts) have been not more frequent than those due to other techniques. Tumor recurrence is minor compared with radiotherapy or surgery. This method is a valid alternative to surgery and/or diathermocoagulation for microsurgery of soft tissues. Our results are at times not consistent with those published in the literature, stressing the concept that multicentric studies that harmonization methodology and the patient selection are vital. PMID:22593693

  9. Experimental measurements of vapor-liquid equilibria of the H2O + CO2 + CH4 ternary system

    Science.gov (United States)

    Qin, J.; Rosenbauer, R.J.; Duan, Zhenhao

    2008-01-01

    Reported are the experimental measurements on vapor-liquid equilibria in the H2O + CO2 + CH4 ternary system at temperatures from (324 to 375) K and pressures from (10 to 50) MPa. The results indicate that the CH4 solubility in the ternary mixture is about 10 % to 40 % more than that calculated by interpolation from the Henry's law constants of the binary system, H2O + CH4, and the solubility of CO2 is 6 % to 20 % more than what is calculated by the interpolation from the Henry's law constants of the binary mixture, H 2O + CO2. ?? 2008 American Chemical Society.

  10. Predicting gas decomposition in an industrialized pulsed CO2 laser

    CSIR Research Space (South Africa)

    Forbes, A

    2005-03-01

    Full Text Available to be stable at O2 levels in excess of 2%, whereas previously reported values suggest stable operation at values of less than 1%. This is thought to be related to the unusually high starting CO2 concentration of the gas mix, and the short time pulse...

  11. Effect of impurities in captured CO2 on liquid-vapor equilibrium

    NARCIS (Netherlands)

    Ahmad, Mohammad; Gernert, Johannes; Wilbers, Erwin

    2014-01-01

    The capture of large amounts of CO2 from power plants and other large CO2 point sources has become relevant within the concept to mitigate CO2 emissions via carbon capture and storage. The objective of this study was to investigate the impact of some major impurities found in the CO2 stream captured

  12. Comparative study of upper lip frenectomy with the CO2 laser versus the Er, Cr: YSGG laser

    Science.gov (United States)

    Pié-Sánchez, Jordi; España-Tost, Antonio J.; Arnabat-Domínguez, Josep

    2012-01-01

    Objectives: To compare upper lip frenulum reinsertion, bleeding, surgical time and surgical wound healing in frenectomies performed with the CO2 laser versus the Er, Cr:YSGG laser. Study design: A prospective study was carried out on 50 randomized pediatric patients who underwent rhomboidal resection of the upper lip frenulum with either the CO2 laser or the Er,Cr:YSGG laser. Twenty-five patients were assigned to each laser system. All patients were examined at 7, 14, 21 days and 4 months after the operation in order to assess the surgical wound healing. Results: Insertion of the frenulum, which was preoperatively located between the upper central incisors, migrated to the mucogingival junction as a result of using both laser systems in all patients. Only two patients required a single dose of 650 mg of paracetamol, one of either study group. CO2 laser registered improved intraoperative bleeding control results and shorter surgical times. On the other hand, the Er,Cr:YSGG laser achieved faster healing. Conclusions: Upper lip laser frenectomy is a simple technique that results in minimum or no postoperative swelling or pain, and which involves upper lip frenulum reinsertion at the mucogingival junction. The CO2 laser offers a bloodless field and shorter surgical times compared with the Er,Cr:YSGG laser. On the other hand, the Er,Cr:YSGG laser achieved faster wound healing. Key words:Frenectomy, upper lip frenulum, CO2 laser, Er,Cr:YSGG laser, laser. PMID:22143683

  13. A new frontier in CO2 flux measurements using a highly portable DIAL laser system

    Science.gov (United States)

    Queiβer, Manuel; Granieri, Domenico; Burton, Mike

    2016-01-01

    Volcanic CO2 emissions play a key role in the geological carbon cycle, and monitoring of volcanic CO2 fluxes helps to forecast eruptions. The quantification of CO2 fluxes is challenging due to rapid dilution of magmatic CO2 in CO2-rich ambient air and the diffuse nature of many emissions, leading to large uncertainties in the global magmatic CO2 flux inventory. Here, we report measurements using a new DIAL laser remote sensing system for volcanic CO2 (CO2DIAL). Two sites in the volcanic zone of Campi Flegrei (Italy) were scanned, yielding CO2 path-amount profiles used to compute fluxes. Our results reveal a relatively high CO2 flux from Campi Flegrei, consistent with an increasing trend. Unlike previous methods, the CO2DIAL is able to measure integrated CO2 path-amounts at distances up to 2000 m using virtually any solid surface as a reflector, whilst also being highly portable. This opens a new frontier in quantification of geological and anthropogenic CO2 fluxes. PMID:27652775

  14. Catalytic Oxidation of CO for Closed-Cycle CO2 Lasers

    Science.gov (United States)

    Miller, I. M.; Schryer, D. R.; Hess, R. V.; Sidney, B. D.; Wood, G. M., Jr.; Paulin, P. A.; Upchurch, B. T.; Brown, K. G.

    1987-01-01

    Stoichiometric mixture converted completely. High-energy pulsed CO2 lasers have potential for measuring many different features of atmosphere of Earth and particularly useful on airborne or space platforms. For this application, laser must be operated in closed cycle to conserve gas, especially if rare nonradioactive isotopes of carbon and oxygen used. However, laser discharge decomposes fraction of CO2 to CO and O2, causing rapid loss in power leading to erratic behavior. To maintain operation, CO and O2 must be recombined to form CO2.

  15. CO2 laser-fabricated cladding light strippers for high-power fiber lasers and amplifiers.

    Science.gov (United States)

    Boyd, Keiron; Simakov, Nikita; Hemming, Alexander; Daniel, Jae; Swain, Robert; Mies, Eric; Rees, Simon; Andrew Clarkson, W; Haub, John

    2016-04-10

    We present and characterize a simple CO2 laser processing technique for the fabrication of compact all-glass optical fiber cladding light strippers. We investigate the cladding light loss as a function of radiation angle of incidence and demonstrate devices in a 400 μm diameter fiber with cladding losses of greater than 20 dB for a 7 cm device length. The core losses are also measured giving a loss of laser diode with minimal heating of the fiber coating and packaging adhesives.

  16. Effectiveness of Er:YAG and CO2 lasers in the management of gingival melanin hyperpigmentation.

    Science.gov (United States)

    Kishore, A; Kathariya, R; Deshmukh, V; Vaze, S; Khalia, N; Dandgaval, R

    2014-06-01

    Although clinical melanin pigmentation does not present itself as a medical problem or a disease entity, "black gums" is a major esthetic complaint for many people, who often requests cosmetic corrections. Gingival depigmentation can be carried out using many procedures; lasers of various types being a new addition. This study was undertaken to evaluate and compare the effectiveness of CO2 and Er:YAG lasers for the treatment of gingival melanin hyper pigmentation. Twenty young age and gender matched subjects were selected for a randomized split mouth depigmentation procedure using Er:YAG (Group A) and CO2 laser (Group B). Parameters evaluated were: Dummet index, Hedin melanin Index, Gingival and Plaque Index, time taken for the procedure, bleeding during the procedure, VAS scale for pain perception and wound healing and patient preference for the procedure. Wilcoxon signed rank test, Chi-square test, paired t test were used to analyze statistical significance between different variables. CO2 laser treatment caused increased pain and delayed wound healing when compared to Er:YAG laser treatment. Although both treatment modalities are highly effective depigmentation procedures, giving excellent esthetics results; when pain, wound healing and patient preferences were considered Er:YAG outscored CO2 Laser. The effectiveness of the Er:YAG and CO2 laser for the treatment of gingival melanin depigmentation was evaluated clinically and histologically, although both treatment modalities are highly effective, giving excellent esthetics results, however, when pain and wound healing were considered Er:YAG was better than CO2 laser.

  17. A comparative study of pulsed Nd:YAG and CO2 laser effect on cardiovascular tissue

    OpenAIRE

    Yova, D.; Papadakis, E.; Kassis, K.; Agapitos, E.; Kavantzas, N.; Koutsouris, D.; Serafetinidis, A.

    1994-01-01

    Percutaneous laser angioplasty is receiving increasing attention, as laser ablation of atheromatous plaque presents advantages to direct surgery or balloon angioplasty. One of the main prerequisites of using powerful pulsed lasers in angioplasty is the optimum choice of the irradiation parameters (the wavelength, the pulse shape and duration, the energy parameters e.t.c.). Infrared lasers have numerous applications in surgery. Among them the pulsed CO2 laser emitting at 10.6 µm and the pulsed...

  18. Direct acceleration of electrons by a CO2 laser in a curved plasma waveguide

    OpenAIRE

    Yi, Longqing; Pukhov, Alexander; Shen, Baifei

    2016-01-01

    Laser plasma interaction with micro-engineered targets at relativistic intensities has been greatly promoted by recent progress in the high contrast lasers and the manufacture of advanced micro- and nano-structures. This opens new possibilities for the physics of laser-matter interaction. Here we propose a novel approach that leverages the advantages of high-pressure CO$_{2}$ laser, laser-waveguide interaction, as well as micro-engineered plasma structure to accelerate electrons to peak energ...

  19. Longitudinally excited CO2 laser with short laser pulse operating at high repetition rate

    Science.gov (United States)

    Li, Jianhui; Uno, Kazuyuki; Akitsu, Tetsuya; Jitsuno, Takahisa

    2016-11-01

    A short-pulse longitudinally excited CO2 laser operating at a high repetition rate was developed. The discharge tube was made of a 45 cm-long or 60 cm-long dielectric tube with an inner diameter of 16 mm and two metallic electrodes at the ends of the tube. The optical cavity was formed by a ZnSe output coupler with a reflectivity of 85% and a high-reflection mirror. Mixed gas (CO2:N2:He = 1:1:2) was flowed into the discharge tube. A high voltage of about 33 kV with a rise time of about 200 ns was applied to the discharge tube. At a repetition rate of 300 Hz and a gas pressure of 3.4 kPa, the 45 cm-long discharge tube produced a short laser pulse with a laser pulse energy of 17.5 mJ, a spike pulse energy of 0.2 mJ, a spike width of 153 ns, and a pulse tail length of 90 μs. The output power was 5.3 W. The laser pulse waveform did not depend on the repetition rate, but the laser beam profile did. At a low repetition rate of less than 50 Hz, the laser beam had a doughnut-like shape. However, at a high repetition rate of more than 150 Hz, the discharge concentrated at the center of the discharge tube, and the intensity at the center of the laser beam was higher. The laser beam profile depended on the distribution of the discharge. An output power of 7.0 W was achieved by using the 60 cm-long tube.

  20. Benefits of cryogenic cooling on the operation of a pulsed CO2 laser

    Indian Academy of Sciences (India)

    2014-01-05

    Jan 5, 2014 ... The paper presents results of a theoretical model of a pulsed electron beam controlled CO2 laser (EBCL) to investigate the effect of cooling on the laser gas mixture. It is shown that cryogenic cooling can significantly improve the performance of the laser. The efficiency of an EBCL improved from 20% to ...

  1. Benefits of cryogenic cooling on the operation of a pulsed CO2 laser

    Indian Academy of Sciences (India)

    2014-01-05

    Jan 5, 2014 ... Abstract. The paper presents results of a theoretical model of a pulsed electron beam controlled. CO2 laser (EBCL) to investigate the effect of cooling on the laser gas mixture. It is shown that cryogenic cooling can significantly improve the performance of the laser. The efficiency of an. EBCL improved from ...

  2. Effect of CO2 milliwatt laser on peripheral nerves: Part I. A dose-response study

    NARCIS (Netherlands)

    Menovsky, T.; van den Bergh Weerman, M.; Beek, J. F.

    1996-01-01

    In order to explore further the role of laser for microneural repair, the effect of CO2 laser irradiation on intact rat sciatic nerves was investigated. In total 40 rat sciatic nerves were exposed to 12 different combinations of laser power (50, 100, and 150 mW) and pulse duration (0.1 to 3 s)

  3. Aesthetic skin resurfacing with the high-energy ultrapulsed CO2 laser.

    Science.gov (United States)

    Weinstein, C; Roberts, T L

    1997-04-01

    CO2 laser resurfacing, using the new generation high-energy output pulsed lasers, provides a highly accurate method of resurfacing and rejuvenating facial skin. Its applications are widespread and well accepted by the general population (Color Figs. 3 to 8). Complications may occur, which may be minimized through adequate laser training and appreciation of the mechanisms of skin healing.

  4. Effect of surface-breakdown plasma on metal drilling by pulsed CO2-laser radiation

    Science.gov (United States)

    Arutiunian, P. V.; Baranov, V. Iu.; Bobkov, I. V.; Bol'Shakov, L. A.; Dolgov, V. A.

    1988-03-01

    The effect of low-threshold surface breakdown produced by short (5-microsec) CO2-laser pulses on the metal drilling process is investigated. Data on the interaction of metals with laser pulses having the same duration but different shape are shown to be different. The effect of the ambient atmospheric pressure on the laser drilling process is investigated.

  5. Effect of the CO2 milliwatt laser on tensile strength of microsutures

    NARCIS (Netherlands)

    Menovsky, T.; Beek, J. F.; van Gemert, M. J.

    1997-01-01

    Laser-assisted tissue repair is often accompanied by a high dehiscence rate, which may be due to alterations in suture material after laser exposure. The goal of this study was to investigate the effect of CO2 laser irradiation on the tensile strength of microsurgical suture material. 10-0 nylon and

  6. Stability information in plasma image of high-power CO 2 laser welding

    Science.gov (United States)

    Li, Guohua; Cai, Yan; Wu, Yixiong

    2009-09-01

    In deep penetration laser welding, a capillary called keyhole is formed when the energy intensity reaches 10 6 W/cm 2. During this process, the vaporized metal and the surrounding atmosphere can be ionized to form plasma both in and above the keyhole. The stability of the keyhole has an important influence on the properties of welded components and the fluctuations of plasma. In this paper, a method was developed to acquire the stability information from plasma images taken by high-speed photography. The influences of surface impurity and the flowrate of side-assist gas on the stability were investigated. Bead-on-plate welding was performed on 12 mm E-grade shipbuilding steel plates using a 15 kW CO 2 laser, with helium as the blowing gas. Three characteristic parameters were used to evaluate the stability. It was found that these three characteristic parameters can effectively indicate the stability variation caused by the surface impurity and gas flowrate. The present research provides important insights into developing image-based sensors to monitor the welding process.

  7. Fluoride plus CO2 laser against the progression of caries in root dentin.

    Science.gov (United States)

    Colucci, Vivian; Messias, Danielle Cristine Furtado; Serra, Mônica Campos; Corona, Silmara Aparecida Milori; Turssi, Cecilia Pedroso

    2012-04-01

    To evaluate the effect of a 1.23% acidulated phosphate fluoride (APF) gel combined with CO2 laser in protecting carious root dentin against further cariogenic challenges. After a 7-day lead-in period, 12 volunteers wore an intraoral palatal device containing four carious root dentin slabs, treated with APF and APF+CO2 or placebo and placebo+CO2. After a 14-day wash-out period, volunteers were crossed-over to the other treatment arm. During both intraoral phases, specimens were submitted to cariogenic challenges and then evaluated for cross-sectional Knoop microhardness. Two-way ANOVA demonstrated that there was significant effect for both main factors: CO2 laser irradiation (P interaction between them (P = 0.4706). Protection of carious root dentin against further cariogenic challenges may be provided by APF fluoride gel and CO2 laser, but no additive benefit was found by combining such strategies.

  8. Antibacterial and Odontogenesis Efficacy of Mineral Trioxide Aggregate Combined with CO2 Laser Treatment.

    Science.gov (United States)

    Hsu, Tuan-Ti; Yeh, Chia-Hung; Kao, Chia-Tze; Chen, Yi-Wen; Huang, Tsui-Hsien; Yang, Jaw-Ji; Shie, Ming-You

    2015-07-01

    Mineral trioxide aggregate (MTA) has been successfully used in clinical applications in endodontics. Studies show that the antibacterial effects of CO2 laser irradiation are highly efficient when bacteria are embedded in biofilm because of a photothermal mechanism. The aim of this study was to confirm the effects of CO2 laser irradiation on MTA with regard to both material characterization and cell viability. MTA was irradiated with a dental CO2 laser using directly mounted fiber optics in the wound healing mode with a spot area of 0.25 cm(2) and then stored in an incubator at 100% relative humidity and 37°C for 1 day to set. The human dental pulp cells cultured on MTA were analyzed along with their proliferation and odontogenic differentiation behaviors. The results indicate that the setting time of MTA after irradiation by the CO2 laser was significantly reduced to 118 minutes rather than the usual 143 minutes. The maximum diametral tensile strength and x-ray diffraction patterns were similar to those obtained without CO2 laser irradiation. However, the CO2 laser irradiation increased the amount of Ca and Si ions released from the MTA and regulated cell behavior. CO2 laser-irradiated MTA promoted odontogenic differentiation of hDPCs, with the increased formation of mineralized nodules on the substrate's surface. It also up-regulated the protein expression of multiple markers of odontogenic and the expression of dentin sialophosphoprotein protein. The current study provides new and important data about the effects of CO2 laser irradiation on MTA with regard to the decreased setting time and increased ion release. Taking cell functions into account, the Si concentration released from MTA with laser irradiation may be lower than a critical value, and this information could lead to the development of new regenerative therapies for dentin and periodontal tissue. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  9. Review of long period fiber gratings written by CO2 laser

    Science.gov (United States)

    Wang, Yiping

    2010-10-01

    This paper presents a systematic review of long period fiber gratings (LPFGs) written by the CO2 laser irradiation technique. First, various fabrication techniques based on CO2 laser irradiations are demonstrated to write LPFGs in different types of optical fibers such as conventional glass fibers, solid-core photonic crystal fibers, and air-core photonic bandgap fibers. Second, possible mechanisms, e.g., residual stress relaxation, glass structure changes, and physical deformation, of refractive index modulations in the CO2 -laser-induced LPFGs are analyzed. Third, asymmetrical mode coupling, resulting from single-side laser irradiation, is discussed to understand unique optical properties of the CO2 -laser-induced LPFGs. Fourthly, several pretreament and post-treatment techniques are proposed to enhance the efficiency of grating fabrications. Fifthly, sensing applications of the CO2 -laser-induced LPFGs are investigated to develop various LPFG-based temperature, strain, bend, torsion, pressure, and biochemical sensors. Finally, communication applications of the CO2 -laser-induced LPFGs are investigated to develop various LPFG-based band-rejection filters, gain equalizers, polarizers, and couplers.

  10. A 5 cm single-discharge CO2 laser having high power output

    NARCIS (Netherlands)

    Ernst, G.J.; Boer, A.G.

    1980-01-01

    A single-discharge self-sustained CO2 laser has been constructed with a gap distance of 5 cm. The system has a very simple construction; it produces a very uniform discharge with an output power of 50 Joules per liter for a CO2 : N2 : He = 1 : 1 : 3 mixture. The efficiency can be as high as 19%.

  11. A computer program for the design of optimum catalytic monoliths for CO2 lasers

    Science.gov (United States)

    Guinn, K.; Goldblum, S.; Noskowski, E.; Herz, R.

    1990-01-01

    Pulsed CO2 lasers have many applications in aeronautics, space research, weather monitoring and other areas. Full exploitation of the potential of these lasers is hampered by the dissociation of CO2 that occurs during laser operation. The development of closed-cycle CO2 lasers requires active CO-O2 recombination (CO oxidation) catalysts and design methods for implementation of catalysts inside lasers. The performance criteria and constraints involved in the design of catalyst configurations for use in a closed-cycle laser are discussed, and several design studies performed with a computerized design program that was written are presented. Trade-offs between catalyst activity and dimensions, flow channel dimensions, pressure drop, O2 conversion and other variables are discussed.

  12. The SHARPLAN family of CO2 lasers for surgery.

    Science.gov (United States)

    Dagan, J

    1984-01-01

    The SHARPLAN laser systems are available with a full range of different powers: a 25 watt office system, a 40 watt and a 60 watt system for general surgery and an 80 watt for high power needs like neurosurgery, all powers measured at tissue. A full range of accessories is available for microsurgery enabling adaptation to the most popular surgical microscopes for cavitational surgery. Super-pulse models are available, minimizing the thermal damage to the tissue exposed to the laser. The interaction of the laser with living tissue and its specific use in neurosurgery are discussed.

  13. The Ablation Properties of CO2 Laser Irradiating to Absorption Media: An In Vitro Study

    Directory of Open Access Journals (Sweden)

    Sajee Sattayut

    2012-01-01

    Full Text Available This study aimed to compare histological affected zone of tissue samples irradiated by defocused CO2 laser at 1, 2, and 3W continuous wave with and without absorption media. The in vitro experiment was conducted in 70 tissue blocks. The samples were randomly allocated into 7 groups: 10 samples each group, namely, the groups irradiated with 1, 2, and 3W, defocused CO2 laser for 5 seconds, the groups irradiated with 1, 2, and 3W, defocused CO2 laser to the absorption media, and the media alone group as a control. Then the samples were stained with Masson’s trichrome and measured the affected borders under light microscope at 10 × 10 magnification. There was no histological alteration in the groups irradiated with the defocused CO2 laser to the absorption media while the groups without using the absorption media showed the tissue alteration by photoablation.

  14. HIGH POWER, HELIUM-FREE, SUPERATMOSPHERIC CO2, MINI-TEA LASER

    OpenAIRE

    Marchetti, S.; Simili, R.; Giorgi, M.

    1987-01-01

    Large Helium -free emissions are obtained in two mini-TEA CO2 lasers , by using always a corona preionization, without additives, with a maximum energy density of 900 J/lt. deposited into the discharge

  15. Assisting Gas Optimization in CO2 Laser Welding

    DEFF Research Database (Denmark)

    Gong, Hui; Olsen, Flemming Ove

    1996-01-01

    High quality laser welding is achieved under the condition of optimizing all process parameters. Assisting gas plays an important role for sound welds. In the conventional welding process assisting gas is used as a shielding gas to prevent that the weld seam oxidates. In the laser welding process...... assisting gas is also needed to control the laser induced plasma.Assisting gas is one of the most important parameters in the laser welding process. It is responsible for obtaining a quality weld which is characterized by deep penetration, no interior imperfections, i.e. porosity, no crack, homogeneous seam...... surface, etc. In this work a specially designed flexible off-axis nozzle capable of adjusting the angle of the nozzle, the diameter of the nozzle, and the distance between the nozzle end and the welding zone is tested. In addition to the nozzle parameters three gases, Nitrogen, Argon, and Helium...

  16. Ablative CO2 lasers for skin tightening: traditional versus fractional.

    Science.gov (United States)

    Ortiz, Arisa E; Goldman, Mitchel P; Fitzpatrick, Richard E

    2014-12-01

    With patients more resistant to invasive treatments and those that result in significant downtime, there has been a rise in using lasers to improve skin laxity and induce tissue tightening as an alternative to surgery. Traditional and fractional ablative resurfacing induces skin tightening through precise dermal heating and a wound-healing effect. The purpose of this review was to discuss the mechanism of action of using ablative lasers to induce skin tightening and compare traditional versus fractional technologies. A review of the literature was performed. The authors discuss traditional and fractional ablative lasers for achieving skin tightening. Neocollagenesis and dermal remodeling seen after ablative resurfacing contributes to the clinical improvement seen in tissue tightening. Fractional photothermolysis may enhance tissue tightening effects of ablative lasers because of its ability to ablate deeper into the reticular dermis without significant risk for scarring.

  17. Third harmonic generation of CO2 laser radiation in AgGaSe2 crystal

    Indian Academy of Sciences (India)

    ... for second harmonic and third harmonic generations are 6.3% and 2.4% respectively with the input fundamental pump power density of 5.9 MW/cm2 only. The wavelength of the fundamental CO2 laser radiation used for the generation of harmonics is 10.6 m, (20) line. A compact TEA CO2 laser source has been built in ...

  18. Fabrication of microlens and microlens array on polystyrene using CO 2 laser

    KAUST Repository

    Fan, Yiqiang

    2011-11-01

    This study presents a new process for fabricating microlens and microlens arrays directly on a surface of polystyrene using a CO2 laser. The working spot of the polystyrene is heated locally by a focused CO2 laser beam, which tends to have a hyperboloid profile due to the surface tension and can be used as a microlens. The microlenses with different dimensions were fabricated by changing the power of the laser beam. Microlens array was also fabricated with multiple scans of the laser beam on the polystyrene surface. © (2012) Trans Tech Publications, Switzerland.

  19. Rapidly tuning miniature transversely excited atmospheric-pressure CO2 laser.

    Science.gov (United States)

    Qu, Yanchen; Ren, Deming; Hu, Xiaoyong; Liu, Fengmei; Zhao, Jingshan

    2002-08-20

    An experimental study of a rapidly tuning miniature transversely excited atmospheric-pressure CO2 laser is reported. To rapidly shift laser wavelengths over selected transitions in the 9-11 microm wavelength region, we have utilized a high-frequency stepping motor and a diffraction grating. The laser is highly automated with a monolithic microprocessor controlled laser line selection. For the achievement of stable laser output, a system of laser excitation with a voltage of 10 kV, providing effective surface corona preionization and allowing one to work at various gas pressures, is utilized. Laser operation at 59 emission lines of the CO2 molecule rotational transition is obtained and at 51 lines, the pulse energy of laser radiation exceeds 30 mJ. The system can be tuned between two different rotational lines spanning the wavelength range from 9.2 to 10.8 microm within 10 ms.

  20. Atomic lithium vapor laser isotope separation

    CERN Document Server

    Olivares, I E

    2002-01-01

    An atomic vapor laser isotope separation in lithium was performed using tunable diode lasers. The method permits also the separation of the isotopes between the sup 6 LiD sub 2 and the sup 7 LiD sub 1 lines using a self-made mass separator which includes a magnetic sector and an ion beam designed for lithium. (Author)

  1. Clinical efficacy of utilizing Ultrapulse CO2 combined with fractional CO2 laser for the treatment of hypertrophic scars in Asians-A prospective clinical evaluation.

    Science.gov (United States)

    Lei, Ying; Li, Shi Feng; Yu, Yi Ling; Tan, Jun; Gold, Michael H

    2017-06-01

    Hypertrophic scarring is seen regularly. Tissue penetration of laser energy into hypertrophic scars using computer defaults from some lasers may be insufficient and penetration not enough. We have developed a treatment with an interrupted laser "drilling" by the Ultrapulse CO2 (Manual Fractional Technology, MFT) and, a second pass, with fractional CO2 . The MFT with fractional CO2 lasers to treat hypertrophic scars is evaluated. A total of 158 patients with hypertrophic scars had three sessions of MFT with fractional CO2 laser at 3-month intervals. Evaluations made before and 6 months after the 3rd treatment: (1) the Vancouver Scar Scale (VSS), (2) the University of North Carolina (UNC) Scar Scale, and (3) a survey of patient satisfaction. All data were analyzed using a t-test before and after treatment. The VSS score decreased from 9.35 to 3.12 (PCO2 laser had profound effects on the hypertrophic scars treated. It works by increasing the penetration depth of the CO2 laser in the scar tissue, exerting more precise effects on the hypertrophic scars. MFT combined with fractional CO2 laser has the potential to be a major advance in the treatment of hypertrophic scars. © 2017 Wiley Periodicals, Inc.

  2. Fractional CO 2 laser resurfacing as monotherapy in the treatment of atrophic facial acne scars

    OpenAIRE

    Imran Majid; Saher Imran

    2014-01-01

    Background: While laser resurfacing remains the most effective treatment option for atrophic acne scars, the high incidence of post-treatment adverse effects limits its use. Fractional laser photothermolysis attempts to overcome these limitations of laser resurfacing by creating microscopic zones of injury to the dermis with skip areas in between. Aim: The aim of the present study is to assess the efficacy and safety of fractional CO 2 laser resurfacing in atrophic facial acne scars. Material...

  3. Gain kinetics of CO2 gasdynamic laser mixtures at high pressure.

    Science.gov (United States)

    Christiansen, W. H.; Tsongas, G. A.

    1971-01-01

    Description of a combined analytical and experimental investigation of rapidly expanded CO2 laser mixtures. Study of the vibrational kinetics indicates that population inversions with high vibrational energy density can be produced at high pressures by utilizing low (starved) concentrations of CO2. Scaling laws for predicting the gain of starved systems are developed. A description is given of gain measurements carried out using a CO2 laser to probe the flow in a nozzle at the point where the Mach number is approximately four. Population inversions at static pressures as high as about 1 atm have been observed and found to be in reasonable agreement with predictions.

  4. Swirling Gas Jet-Assisted Laser Trepanning for a Galvanometer-Scanned CO2 Laser

    Directory of Open Access Journals (Sweden)

    Chao-Ching Ho

    2017-05-01

    Full Text Available Laser-drilled hole arrays are part of an important field that aim to improve efficiency without affecting the quality of laser-drilled holes. In this paper, a swirling gas jet was implemented to assist with laser trepanning for a galvanometer scanned CO2 laser. The proposed swirling gas jet is based on laser trepanning. This swirling gas jet nozzle was composed of four inlet tubes to produce the flow of the vortex. Then, the plume particles were excluded, and spatter on the surface of the workpiece decreased. Thus, this approach can mitigate the problem of overcooling. This study manipulated the appropriate parameter settings, which were simulated by computational fluid dynamics software ANSYS CFX. The proposed swirling gas jet can be used with galvanometer-based scanner systems to keep the laser beam from interference by spatter. In addition, a hollow position of the vortex was achieved by using the four inlet tubes, which resulted in pressure asymmetry in the nozzle and velocity distribution on the surface of the workpiece. The experiment verified that the depth of processing could be enhanced by 110% when trepanning at a scanning speed of 30 mm/s, and that the removal of volume could be enhanced by 71% in trepanning at a diameter of 1 mm by using a swirl assistant compared with a non-assisted condition. Furthermore, the material removal rate of the swirling jet increases when the machining area of the galvanometer-based scanner is larger.

  5. High Efficiency Mask Based Laser Materials Processing with TEA-CO2 - and Excimer Laser

    DEFF Research Database (Denmark)

    Bastue, Jens; Olsen, Flemmming Ove

    1997-01-01

    In general, mask based laser materials processing techniques suffer from a very low energy efficiency. We have developed a simple device called an energy enhancer, which is capable of increasing the energy efficiency of typical mask based laser materials processing systems. A short review of the ...... line marking with TEA-CO2 laser of high speed canning lines. The second one is manufactured for marking or microdrilling with excimer laser.......In general, mask based laser materials processing techniques suffer from a very low energy efficiency. We have developed a simple device called an energy enhancer, which is capable of increasing the energy efficiency of typical mask based laser materials processing systems. A short review...... of the most widely used applications of these systems is given and the potential advantages of the energy enhancer are discussed.The basic principle behind the energy enhancing technique is explained and two new energy enhancers are presented and evaluated. The first one is designed especially for single text...

  6. BESTIA - The next generation ultra-fast CO2 laser for advanced accelerator research

    Science.gov (United States)

    Pogorelsky, Igor V.; Babzien, Markus; Ben-Zvi, Ilan; Skaritka, John; Polyanskiy, Mikhail N.

    2016-09-01

    Over the last two decades, BNL's ATF has pioneered the use of high-peak power CO2 lasers for research in advanced accelerators and radiation sources. Our recent developments in ion acceleration, Compton scattering, and IFELs have further underscored the benefits from expanding the landscape of strong-field laser interactions deeper into the mid-infrared (MIR) range of wavelengths. This extension validates our ongoing efforts in advancing CO2 laser technology, which we report here. Our next-generation, multi-terawatt, femtosecond CO2 laser will open new opportunities for studying ultra-relativistic laser interactions with plasma in the MIR spectral domain, including new regimes in the particle acceleration of ions and electrons.

  7. Angular distribution of debris from CO2 and YAG laser-produced tin plasmas

    Science.gov (United States)

    Campos, D.; Coons, R. W.; Fields, M. D.; Crank, M.; Harilal, S. S.; Hassanein, A.

    2010-04-01

    We investigated the angular dependence of atomic and ionic debris from CO2 and YAG laser-produced tin plasmas. Several diagnostic techniques were employed for this study including a Faraday cup, witness plates and subsequent x-ray photoelectron spectroscopic analysis, optical emission spectroscopy etc. It was found that the debris emission from the Nd:YAG laser-produced plasmas fell sharply from the target normal. In contrast, the debris emission from the CO2 laser-produced plasmas was almost constant at short angles from the target normal. Our results also indicated that the plasma produced by the CO2 laser emitted less atomic and ionic debris compared to a plasma produced by Nd:YAG laser.

  8. 10-year experience of CO2-laser application in ambulance gynecology

    Science.gov (United States)

    Stachanov, Michael L.; Masychev, Victor I.; Velsher, Leonid Z.; Kirkin, Vladimir V.; Zhashkov, Roman V.; Kocharian, Emilia A.

    2000-10-01

    CO2-laser surgical systems have come to stay in everyday practice of modern physicians and are successfully used in colposcopic and laparoscopic surgery. Results, obtained in ambulance gynecology are especially impressing. CO2- laser provides high medical- and cost-effective treatment. Presented work describes many-years experience of CO2- laser application. 439 patients with various vulvaric and cervix diseases were operated within this period. Laser beam parameters were selected according to requirements ((tau) =4 J/cm2) treatment without carbonization. Analyses of the results showed that the laser successfully destructs uterine cervix erosion, endocervicosis, dysplasia, leukoplakia, eritoplakia of uterine cervix, various benignant pathologies and focus degenerative process in ambulate conditions.

  9. Laser Wakefield Acceleration Driven by a CO2 Laser (STELLA-LW) - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Wayne D

    2008-06-27

    The original goals of the Staged Electron Laser Acceleration – Laser Wakefield (STELLA-LW) program were to investigate two new methods for laser wakefield acceleration (LWFA). In pseudo-resonant LWFA (PR-LWFA), a laser pulse experiences nonlinear pulse steepening while traveling through the plasma. This steepening allows the laser pulse to generate wakefields even though the laser pulse length is too long for resonant LWFA to occur. For the conditions of this program, PR-LWFA requires a minimum laser peak power of 3 TW and a low plasma density (10^16 cm^-3). Seeded self-modulated LWFA (seeded SM-LWFA) combines LWFA with plasma wakefield acceleration (PWFA). An ultrashort (~100 fs) electron beam bunch acts as a seed in a plasma to form a wakefield via PWFA. This wakefield is subsequently amplified by the laser pulse through a self-modulated LWFA process. At least 1 TW laser power and, for a ~100-fs bunch, a plasma density ~10^17 cm^-3 are required. STELLA-LW was located on Beamline #1 at the Brookhaven National Laboratory (BNL) Accelerator Test Facility (ATF). The ATF TW CO2 laser served as the driving laser beam for both methods. For PR-LWFA, a single bunch was to probe the wakefield produced by the laser beam. For seeded SM-LWFA, the ATF linac would produce two bunches, where the first would be the seed and the second would be the witness. A chicane would compress the first bunch to enable it to generate wakefields via PWFA. The plasma source was a short-length, gas-filled capillary discharge with the laser beam tightly focused in the center of the capillary, i.e., no laser guiding was used, in order to obtain the needed laser intensity. During the course of the program, several major changes had to be made. First, the ATF could not complete the upgrade of the CO2 laser to the 3 TW peak power needed for the PR-LWFA experiment. Therefore, the PR-LWFA experiment had to be abandoned leaving only the seeded SM-LWFA experiment. Second, the ATF discovered that the

  10. Fractional CO2 Laser Pretreatment Facilitates Transdermal Delivery of Two Vitamin C Derivatives

    Directory of Open Access Journals (Sweden)

    Chien-Yu Hsiao

    2016-11-01

    Full Text Available Background: Topical vitamin C derivatives have been used to treat melasma and used as a skin whitener. The aim of this study was to compare skin histology and permeation of l-ascorbic acid 2-phosphate sesquimagnesium salt (MAP-1 and magnesium l-ascorbic acid-2-phosphate (MAP-2 after fractional CO2 laser pretreatment. Methods: The effect of fractional laser treatment on porcine skin was examined by scanning electron microscopy and confocal laser scanning electron microscopy. The effect of fractional CO2 laser treatment of different fluencies and pass numbers on transdermal flux of the two vitamin C derivatives through porcine skin was examined in vitro using a Franz diffusion chamber. Results: Fluxes of MAP-1 and MAP-2 across fractional CO2 laser-treated (5 W skin were eight- to 13-fold, and 20- to 22-fold higher, respectively, than the fluxes of these compounds across intact skin. Fluxes of MAP-1 and MAP-2 across fractional CO2 laser-treated (9 W skin were 14- to 19-fold, and 30- to 42-fold higher, respectively, than their fluxes across intact skin. Conclusion: Fractional CO2 laser treatment is an effective way of delivering vitamin C derivatives into the skin.

  11. Fractional CO2 lasers contribute to the treatment of stable non-segmental vitiligo.

    Science.gov (United States)

    Yuan, Jinping; Chen, Hongqiang; Yan, Ru; Cui, Shaoshan; Li, Yuan-Hong; Wu, Yan; Gao, Xing-Hua; Chen, Hong-Duo

    2016-12-01

    Stable non-segmental vitiligo is often resistant to conventional therapies. The purpose of this study was to investigate the effect of three types of fractional lasers in the treatment of stable non-segmental vitiligo. Twenty patients were enrolled in the study. The vitiligo lesions of each patient were divided into four treatment parts, and all parts were treated with narrowband ultraviolet-B (NB-UVB). Three of the four parts were respectively treated with three types of fractional lasers (two ablative 10,600-nm CO2 lasers and one non-ablative 1,565-nm laser), followed by topical betamethasone solution application. The treatment period lasted six months. Efficacy and satisfaction were respectively assessed by dermatologists and patients. The ablative CO2 lasers, in combination with topical betamethasone solution and NB-UVB, achieved marked to excellent improvement on white patches assessed by dermatologists. Patients showed high satisfaction scores for the treatments. The non-ablative 1,565-nm fractional laser did not provide any further benefit in the treatment of vitiligo. No severe adverse events developed for any of the treatments. The treatment protocol with ablative CO2 lasers, in combination with topical betamethasone solution and NB-UVB, was suitable for stable non-segmental vitiligo. For vitiligo, the ablative fractional CO2 laser is more effective than the non-ablative fractional laser.

  12. A new modality for fractional CO2 laser resurfacing for acne scars in Asians.

    Science.gov (United States)

    Huang, Luping

    2013-02-01

    Since fractional photothermolysis was first introduced in 2004, it has become a very popular procedure, especially with more and more ablative fractional laser systems and treatments. Fractional ablative laser has been shown to be very effective; however, it does not reach the efficacy of conventional ablative laser treatments in most instances. In an attempt order to make the fractional CO2 laser treatment more efficacious and safe, we combined both the conventional CO2 laser and the fractional CO2 laser to treat acne scars. We report our experience with this new modality. A total of 44 Chinese patients with facial acne scars and skin type IV were included in this study. Each patient received a minimum of two treatment sessions. For each laser session, both the conventional CO2 laser treatment and the DeepFX laser treatment were focused on treating the scar areas only. Following this technique, the more superficialf ActiveFX fractional CO2 laser was performed to the entire face. The efficacy of the procedure was evaluated 3 months after the final laser treatment. The improvement in acne scars and the overall skin texture change were assessed by photographic evaluation using the following scales: ≤25 % (mild), 26-50 % (moderate), 51-75 % (marked), and >75 % (excellent). Side effects from this therapy were mild to moderate. Two cases of HSV outbreak were noted; they were treated and resolved without adverse sequelae. Post-laser erythema was resolved within 1 month in one half of the patients. Prolonged erythema (≤3 months) was noted in 12(27 %) cases. Temporary post-inflammatory hyperpigmentation (PIH; ≤1 month) was seen in approximately 50 % of the patients. PIH (≤3 months) was noted in four cases (9 %). Sixty-four percent of the patients (28/44) had an improvement of between 51 and 75 % after more than two sessions of the combination of laser treatments. The average overall improvement was 52.50 % (±12.25 %). Three patients achieved

  13. Direct acceleration of electrons by a CO2 laser in a curved plasma waveguide

    CERN Document Server

    Yi, Longqing; Shen, Baifei

    2016-01-01

    Laser plasma interaction with micro-engineered targets at relativistic intensities has been greatly promoted by recent progress in the high contrast lasers and the manufacture of advanced micro- and nano-structures. This opens new possibilities for the physics of laser-matter interaction. Here we propose a novel approach that leverages the advantages of high-pressure CO 2 laser, laser-waveguide interaction, as well as micro-engineered plasma structure to accelerate electrons to peak energy greater than 1 GeV with narrow slice energy spread (~1%) and high overall efficiency. The acceleration gradient is 26 GV/m for a 1.3 TW CO2 laser system. The micro-bunching of a long electron beam leads to the generation of a chain of ultrashort electron bunches with the duration roughly equal to half-laser-cycle. These results open a way for developing a compact and economic electron source for diverse applications.

  14. Fractional CO2 laser treatment to enhance skin permeation of tranexamic acid with minimal skin disruption.

    Science.gov (United States)

    Hsiao, Chien-Yu; Sung, Hsin-Ching; Hu, Sindy; Huang, Chun-Hsun

    2015-01-01

    Topical tranexamic acid has been used to treat melasma and as a skin whitener. The aim of this study was to compare the skin histology and permeation of tranexamic acid after fractional and conventional CO2 laser pretreatment. The effect of treatment with different strengths of fractional and conventional CO2 laser treatment was examined by scanning and transmission electron microscopy. Permeation of tranexamic acid through porcine skin was tested in vitro using a Franz diffusion chamber. Four passes of fractional laser treatment caused less skin damage than conventional laser treatment at the same fluency. Fractional laser treatment caused at least 85% of the cumulative tranexamic aid permeation at the same fluency, and as fluency increased, the number of passes needed to achieve this goal decreased. Fractional laser treatment is as effective as conventional laser treatment in enhancing tranexamic acid delivery and causes less skin damage.

  15. Direct acceleration of electrons by a CO$_{2}$ laser in a curved plasma waveguide

    CERN Document Server

    Yi, Longqing; Shen, Baifei

    2016-01-01

    Laser plasma interaction with micro-engineered targets at relativistic intensities has been greatly promoted by recent progress in the high contrast lasers and the manufacture of advanced micro- and nano-structures. This opens new possibilities for the physics of laser-matter interaction. Here we propose a novel approach that leverages the advantages of high-pressure CO$_{2}$ laser, laser-waveguide interaction, as well as micro-engineered plasma structure to accelerate electrons to peak energy greater than 1 GeV with narrow slice energy spread ($\\sim1\\%$) and high overall efficiency. The acceleration gradient is 26 GV/m for a 1.3 TW CO$_{2}$ laser system. The micro-bunching of a long electron beam leads to the generation of a chain of ultrashort electron bunches with the duration roughly equal to half-laser-cycle. These results open a way for developing a compact and economic electron source for diverse applications.

  16. Investigation of stress induced by CO2 laser processing of fused silica optics for laser damage growth mitigation.

    Science.gov (United States)

    Gallais, Laurent; Cormont, Philippe; Rullier, Jean-Luc

    2009-12-21

    Laser damage mitigation' is a process developed to prevent the growth of nanosecond laser-initiated damage sites under successive irradiation. It consists of re-fusing the damage area with a CO2 laser. In this paper we investigate the stress field created around mitigated sites which could have an influence on the efficiency of the process. A numerical model of CO2 laser interaction with fused silica is developed. It takes into account laser energy absorption, heat transfer, thermally induced stress and birefringence. Residual stress near mitigated sites in fused silica samples is characterized with specific photoelastic methods and theoretical data are compared to experiments. The stress distribution and quantitative values of stress levels are obtained for sites treated with the CO2 laser in various conditions of energy deposition (beam size, pulse duration, incident power). The results provided evidence that the presence of birefringence/residual stress around the mitigated sites has an effect on their laser damage resistance.

  17. Pseudoxanthoma Elasticum Treatment with Fractional CO2 Laser

    Directory of Open Access Journals (Sweden)

    Alessandra Grassi Salles, MD, PhD

    2014-09-01

    Full Text Available Summary: Pseudoxanthoma elasticum (PE is a rare genetic disease characterized by calcification and fragmentation of elastic fibers of the skin, retina, and cardiovascular system. We report a case of PE in which fractional carbon dioxide laser treatment was successfully used to achieve improvement of the cervical skin with 2-year follow-up, in a patient with Fitzpatrick skin type IV. After the fifth session, the patient presented with a local herpes infection. The postlaser reaction of the PE skin was similar to that of the normal skin, in terms of the duration of redness, pain, swelling, and duration of crusting. The overall cosmetic result was satisfactory, with improvement in skin texture, irregularity, volume, and distensibility. The herpetic infection reinforces the value of antiviral prophylaxis during laser treatment of extrafacial areas.

  18. Comparative study of upper lip frenectomy with the CO2 laser versus the Er, Cr: YSGG laser

    OpenAIRE

    Pié-Sánchez, Jordi; España-Tost, Antonio J.; Arnabat-Domínguez, Josep; Gay-Escoda, Cosme

    2011-01-01

    Objectives: To compare upper lip frenulum reinsertion, bleeding, surgical time and surgical wound healing in frenectomies performed with the CO2 laser versus the Er, Cr:YSGG laser. Study design: A prospective study was carried out on 50 randomized pediatric patients who underwent rhomboidal resection of the upper lip frenulum with either the CO2 laser or the Er,Cr:YSGG laser. Twenty-five patients were assigned to each laser system. All patients were examined at 7, 14, 21 days and 4 months aft...

  19. Comparative study of upper lip frenectomy with the CO 2 laser versus the Er, Cr:YSGG laser

    OpenAIRE

    Pié Sánchez, J.; España Tost, Antonio Jesús; Arnabat Domínguez, Josep; Gay Escoda, Cosme

    2012-01-01

    Objectives: To compare upper lip frenulum reinsertion, bleeding, surgical time and surgical wound healing in frenectomies performed with the CO 2 laser versus the Er, Cr:YSGG laser. Study design: A prospective study was carried out on 50 randomized pediatric patients who underwent rhomboidal resection of the upper lip frenulum with either the CO 2 laser or the Er,Cr:YSGG laser. Twenty-five patients were assigned to each laser system. All patients were examined at 7, 14, 21 days and 4 months a...

  20. Adaptive metal mirror for high-power CO2 lasers

    Science.gov (United States)

    Jarosch, Uwe-Klaus

    1996-08-01

    Spherical mirrors with a variable radius of curvature are used inside laser resonators as well as in the beam path between the laser and the workpiece. Commercially-available systems use piezoelectric actuators, or the pressure of the coolant, to deform the mirror surface. In both cases, the actuator and the cooling system influence each other. This interaction is avoided through the integration of the cooling system with the flexible mirror membrane. A multi- channel design leads to an optimized cooling effect, which is necessary for high power applications. The contour of the variable metal mirror depends on the mounting between the membrane and the mirror body and on the distribution of forces. Four cases of deformation can be distinguished for a circular elastic membrane. The realization of an adaptive metal mirror requires a technical compromise to be made. A mechanical construction is presented which combines an elastic hinge with the inlet and outlet of the coolant. For the deformation of the mirror membranes two actuators with different character of deformation are used. The superposition of the two deformations results in smaller deviations from the spherical surface shape than can be achieved using a single actuator. DC proportional magnets have been introduced as cheap and rigid actuators. The use of this adaptive mirror, either in a low pressure atmosphere of a gas laser resonator, or in an extra-cavity beam path is made possible through the use of a ventilation system.

  1. Acoustic waves in transversely excited atmospheric CO2 laser discharges: effect on performance and reduction techniques

    CSIR Research Space (South Africa)

    von Bergmann, HM

    2008-08-01

    Full Text Available Results are presented on the influence of acoustic waves on the performance of high-repetition-rate TEA CO2 lasers. It is shown that acoustic waves generated inside the laser cavity lead to nonuniform discharges, resulting in a deterioration...

  2. Third harmonic generation of CO2 laser radiation in AgGaSe2 crystal

    Indian Academy of Sciences (India)

    September 2000 physics pp. 405–412. Third harmonic generation of CO2 laser radiation in. AgGaSe2 crystal. GOPAL C BHAR, PATHIK KUMBHAKAR. ½. , D V SATYANARAYANA. ¾. ,. N S N BANERJEE. ¾. , U NUNDY. ¾ and C G CHAO. ¿. Laser Laboratory, Physics Department, Burdwan University, Burdwan 713 104, ...

  3. A compact spark pre-ionized pulser sustainer TE–CO2 laser

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Abstract. A compact spark pre-ionized pulser sustainer TE–CO2 laser that can produce an output energy of one joule with an overall efficiency of 12·4% is presented. Optical pulses have durations of 7·15µs FWHM. Here, the laser uses all solid-state excitation (ASSE) circuit and the discharge formed between two.

  4. Effectiveness of CO2 laser in removal of papillary gingival hyperplasia

    Directory of Open Access Journals (Sweden)

    Sabrina Kívia Correia Gama

    2012-04-01

    Full Text Available INTRODUCTION: Laser applications have increased in a variety of dental procedures, especially in surgeries of soft tissues. Radiation is not invasive and is very well tolerated by tissues. CO2 laser acts in small vessels promoting blood coagulation, making it possible to work in a controlled way. Patients undergoing fixed orthodontic therapy often present injuries of gingival hyperplasia, originating esthetical and functional problems. OBJECTIVE: This study aimed at evaluating the CO2 laser effectiveness in removal of hyperplasia lesions in gingival papilla regions of patients with fixed orthodontic appliances. For this, ten patients were chosen and in these 75 teeth with gingival hyperplasia were identified. Measures from the papilla to incisal edge were performed with the use of a digital caliper. Besides that, the individuals were submitted to previous examinations to the surgical procedure with laser: Full blood count, blood coagulation profile and fasting blood glucose. After this, patients were submitted to the surgery for lesion removal, carried out at the Laser Center of FOUFBA, utilizing a CO2 laser machine (Sharplan 20C, Tel Aviv, Israel. RESULTS: It was showed that laser provided a significant increase (p<0,001 in the distance from the papilla to the incisal edge of the teeth, with no tissue contraction, aspects which were maintained for over two months. CONCLUSION: It can be concluded that CO2 laser has proved to be effective in removal of papillary gingival hyperplasia lesions.

  5. Temperature response of biological materials to pulsed non-ablative CO2 laser irradiation

    NARCIS (Netherlands)

    Brugmans, M. J.; Kemper, J.; Gijsbers, G. H.; van der Meulen, F. W.; van Gemert, M. J.

    1991-01-01

    This paper presents surface temperature responses of various tissue phantoms and in vitro and in vivo biological materials in air to non-ablative pulsed CO2 laser irradiation, measured with a thermocamera. We studied cooling off behavior of the materials after a laser pulse, to come to an

  6. Finding Optimum Focal Point Position with Neural Networks in CO2 Laser Welding

    DEFF Research Database (Denmark)

    Gong, Hui; Olsen, Flemming Ove

    1997-01-01

    CO2 lasers are increasingly being utilized for quality welding in production. Considering the high equipment cost, the start-up time and set-up time should be minimized. Ideally the parameters should be set up and optimized more or less automatically. In this article neural networks are designed...... to optimize the focal point position, one of the most critical parameters in laser welding. The feasibility to automatically optimize the focal point position is analyzed. Preliminary tests demonstrate that neural networks can be used to optimize the focal point position with good accuracy in CW CO2 laser...

  7. H2O and CO2 vapor pressure measurements at temperatures relevant to the middle atmosphere of Earth and Mars

    Science.gov (United States)

    Nachbar, M.; Duft, D.; Leisner, T.

    2017-09-01

    Measurements of the vapor pressure of H2O and CO2 at temperatures relevant to the middle atmosphere of Earth and Mars are rare but important in order to describe cloud formation and ice particle growth processes. In this contribution we present a novel technique for measuring the vapor pressure of condensable gases by analyzing the depositional growth rates on free nanoparticles at high supersaturation. The method is applied to measure the vapor pressure of CO2 between 75K and 85K. By comparison with previous measurements and parameterizations we are able to show the excellent functionality of the method. In addition, the method is used to measure the vapor pressure over H2O ice between 135K and 160K. We show that the vapor pressure of so called stacking disordered ice Isd deposited at temperatures below 160K is significantly higher compared to hexagonal ice Ih. The consequences for ice cloud formation in the atmosphere of Earth and Mars will be discussed.

  8. Volcanic CO2 flux measurement at Campi Flegrei by tunable diode laser absorption spectroscopy

    Science.gov (United States)

    Pedone, M.; Aiuppa, A.; Giudice, G.; Grassa, F.; Cardellini, C.; Chiodini, G.; Valenza, M.

    2014-04-01

    Near-infrared room temperature tunable diode lasers (TDL) have recently found increased usage in atmospheric chemistry and air monitoring research, but applications in volcanology are still limited to a few examples. Here, we explored the potential of a commercial infrared laser unit (GasFinder 2.0 from Boreal Laser Ltd) for measurement of volcanic CO2 mixing ratios, and ultimately for estimating the volcanic CO2 flux. Our field tests were conducted at Campi Flegrei near Pozzuoli, Southern Italy, where the GasFinder was used during three campaigns in October 2012, January 2013 and May 2013 to repeatedly measure the path-integrated mixing ratios of CO2 along cross sections of the atmospheric plumes of two major fumarolic fields (Solfatara and Pisciarelli). By using a tomographic post-processing routine, we resolved, for each of the two fields, the contour maps of CO2 mixing ratios in the atmosphere, from the integration of which (and after multiplication by the plumes' transport speeds) the CO2 fluxes were finally obtained. We evaluate a total CO2 output from the Campi Flegrei fumaroles of ˜490 Mg/day, in line with independent estimates based on in situ (Multi-GAS) observations. We conclude that TDL technique may enable CO2 flux quantification at other volcanoes worldwide.

  9. Clinical applications of CO2 laser resurfacing in the treatment of various pathologic skin disorders

    Science.gov (United States)

    Giler, Shamai

    1997-12-01

    CO2 laser skin resurfacing devices are widely used in cosmetic surgery for the treatment of facial rhytides, acne scars and aging skin. This technique is also useful in the treatment of various benign and premalignant or multiple pathological skin conditions and disorders originating in the epidermal, dermal and skin appendages, vascular lesions, epidermal nevi, infected wounds and ulcers, and keloids. Various surgical techniques have been developed in our clinic using laser resurfacing in the treatment of more than 2,000 patients with various skin pathologic disorders. We describe our experience with the various techniques used. The precise depth control and ablation properties combined with the hemostatic and sterilizing effects of the CO2 laser beam, reduction of the possibility of bleeding, infection and damage to healthy tissues, make the CO2 laser resurfacing techniques the treatment of choice for cosmetic surgery and treatment of benign, premalignant and multiple pathologic skin conditions.

  10. Spatial temperature distribution in human hairy and glabrous skin after infrared CO2 laser radiation.

    Science.gov (United States)

    Frahm, Ken S; Andersen, Ole K; Arendt-Nielsen, Lars; Mørch, Carsten D

    2010-11-08

    CO2 lasers have been used for several decades as an experimental non-touching pain stimulator. The laser energy is absorbed by the water content in the most superficial layers of the skin. The deeper located nociceptors are activated by passive conduction of heat from superficial to deeper skin layers. In the current study, a 2D axial finite element model was developed and validated to describe the spatial temperature distribution in the skin after infrared CO2 laser stimulation. The geometry of the model was based on high resolution ultrasound scans. The simulations were compared to the subjective pain intensity ratings from 16 subjects and to the surface skin temperature distributions measured by an infrared camera. The stimulations were sensed significantly slower and less intense in glabrous skin than they were in hairy skin (MANOVA, p 0.90, p CO2 laser stimulation intensity, temperature levels and nociceptor activation.

  11. Spatial temperature distribution in human hairy and glabrous skin after infrared CO2 laser radiation

    DEFF Research Database (Denmark)

    Frahm, Ken Steffen; Andersen, Ole K.; Arendt-Nielsen, Lars

    2010-01-01

    Background: CO(2) lasers have been used for several decades as an experimental non-touching pain stimulator. The laser energy is absorbed by the water content in the most superficial layers of the skin. The deeper located nociceptors are activated by passive conduction of heat from superficial...... to deeper skin layers. Methods: In the current study, a 2D axial finite element model was developed and validated to describe the spatial temperature distribution in the skin after infrared CO(2) laser stimulation. The geometry of the model was based on high resolution ultrasound scans. The simulations were...... dimensional heat distribution models, the current two dimensional model provides new possibilities for detailed studies regarding CO(2) laser stimulation intensity, temperature levels and nociceptor activation....

  12. High quality electron bunch generation with CO2-laser-plasma interaction

    Science.gov (United States)

    Zhang, Lingang; Shen, Baifei; Xu, Jiancai; Ji, Liangliang; Zhang, Xiaomei; Wang, Wenpeng; Zhao, Xueyan; Yi, Longqing; Yu, Yahong; Shi, Yin; Xu, Tongjun; Xu, Zhizhan

    2015-02-01

    CO2 laser-driven electron acceleration in low-density plasma is demonstrated using particle-in-cell simulation. An intense CO2 laser pulse of long wavelength excites a wake bubble that has a large elongated volume for accelerating a large number of electrons before reaching the charge saturation limit. A transversely injected laser pulse is used to induce and control the electron injection. It is found that an electron bunch with total charge up to 10 nC and absolute energy spread less than 16 MeV can be obtained. As a result, the charge per energy interval of the bunch reaches up to 0.6 nC/MeV. Intense CO2-laser based electron acceleration can provide a new direction for generating highly charged electron bunches with low energy spread, which is of much current interest, especially for table-top X-ray generation.

  13. In situ testing of CO2 laser on dental pulp function: Effects on microcirculation

    Energy Technology Data Exchange (ETDEWEB)

    Friedman, S.; Liu, M.; Doerscher-Kim, J.K.; Kim, S. (Department of Endodontics, Hadassah-Hebrew University School of Dental Medicine, Jerusalem (Israel))

    1991-01-01

    The effect of CO2 laser irradiation on pulpal microcirculation was studied in cat canines. The enamel surfaces of 4 teeth were exposed with energy densities of 304-1440J/cm2, using either a handpiece or a microslad, with a focal spot of 0.21mm and 0.33mm respectively. Pulpal blood flow (PBF) before and following lasing was recorded through the intact tooth surface by a laser Doppler flowmeter. CO2 laser irradiation caused an increase in PBF, which was immediate and transient. The PBF increase was higher in a large pulp than in a small pulp, and it was inversely related to the focal spot size. These findings confirm that the dental pulp is thermally affected by CO2 lasing of the tooth surface, however, without extensive pulp coagulation. It is concluded that the effects of laser irradiation on the pulpal microcirculation may be studied in situ by means of the presented methodology.

  14. Phase-locking of annular-combination CO2 laser

    Science.gov (United States)

    Qi, Tingxiang; Chen, Mei; Zhang, Rongzhu; Xiao, Qianyi

    2015-07-01

    A new annular-combination resonator structure adopting the external-injection phase-locking technology is presented theoretically for that the beam quality of stable annular resonator is not satisfying. The phase-locking principle and feasibility are characterized by energy density of injection beam and coupling coefficient. Based on the diffraction theory, output mode of the resonator with phase-locking is deduced and simulated. Results also confirm that injection beam have a good control effect on output mode. The intensity distributions of output beam are studied briefly and indicate that this new resonator which is adaptable to annular gain media can produce high-power laser beam with high quality.

  15. Mathematical model for CO2 laser high precision ablation of fused silica

    Science.gov (United States)

    He, Ting; Shao, Jianda; Wei, Chaoyang; Jiang, Zhigang; Zhao, Jiaoling

    2017-08-01

    Optics manufactured by mechanical grinding and polishing inevitably will bring surface/subsurface damages and defects during the machining process. Laser polishing has been demonstrated as a technique capable of achieving ultra-smooth surface with no damage and low-defects, but by far optics polished by this technology are only sufficient for illumination applications. To achieve high quality optics, high precision laser ablation has been proved to be a promising technology for shape correction. With pulsed CO2 laser, high precision laser ablation can be performed by direct evaporation of unwanted surface asperities. To acquire nanometer scale high precision ablation, an accurate control and meticulous adjustment of temperature should be needed. Herein, a mathematical model has been established to assist the understanding of the thermal mechanism of CO2 laser ablation and subsequently a series of simulations have been extended to investigate the phase change of evaporation. The temperature of fused silica irradiated by CO2 laser can be controlled via laser power and pulse duration. To achieve nanometer ablation depth, a gentle evaporation regime at low laser intensity is necessary. The results indicated that the ablation depth linearly depend on laser fluence and depth control levels of nanometer are obtainable with the control of laser fluence.

  16. Nd:YAG and CO2 laser therapy of oral mucosal lesions.

    Science.gov (United States)

    White, J M; Chaudhry, S I; Kudler, J J; Sekandari, N; Schoelch, M L; Silverman, S

    1998-12-01

    Experiences gained in the management of oral mucosal lesions by CO2 and Nd:YAG laser therapy in an outpatient clinic treated over an 80-year period are described. Lasers have indications for use in dentistry for incision, excision, and coagulation of intraoral soft tissue. Advances in laser technology have provided delivery systems for site-specific delivery of laser energy with short interaction items on tissue to be ablated. This study retrospectively evaluates a series of clinical case studies. Sixty-four patients with a variety of benign oral soft tissue lesions were treated by laser excision. Thirty-five patients were treated by a pulsed fiberoptic delivered Nd:YAG contact laser, and 29 by a continuous free-beam CO2 non-contact laser. The largest group of lesions treated were leukoplakia (39 cases). Other lesions excised and biopsied were lichen planus, squamous papilloma, pyogenic granuloma, focal melanosis, nonhealing traumatic ulceration, hemangioma, and lymphangioma. All patients were followed postoperatively (mean 6.8 months, range 1-36 months). Laser excision was well tolerated by patients with no intraoperative or postoperative adverse effects. All patients healed postsurgically with no loss of function. CO2 and Nd:YAG lasers are successful surgical options when performing excision of benign intraoral lesions. Advantages of laser therapy include minimal postoperative pain, conservative site-specific minimally invasive surgeries, and elimination of need for sutures.

  17. Surface modification of the titanium implant using TEA CO 2 laser pulses in controllable gas atmospheres - Comparative study

    Science.gov (United States)

    Ciganovic, J.; Stasic, J.; Gakovic, B.; Momcilovic, M.; Milovanovic, D.; Bokorov, M.; Trtica, M.

    2012-01-01

    Interaction of a TEA CO2 laser, operating at 10.6 μm wavelength and pulse duration of 100 ns (FWHM), with a titanium implant in various gas atmospheres was studied. The Ti implant surface modification was typically studied at the moderate laser beam energy density/fluence of 28 J/cm2 in the surrounding of air, N2, O2 or He. The energy absorbed from the TEA CO2 laser beam is partially converted to thermal energy, which generates a series of effects, such as melting, vaporization of the molten material, shock waves, etc. The following titanium implant surface changes and phenomena were observed, depending on the gas used: (i) creation of cone-like surface structures in the atmospheres of air, N2 and O2, and dominant micro-holes/pores in He ambient; (ii) hydrodynamic features, most prominent in air; (iii) formation of titanium nitride and titanium oxide layers, and (iv) occurrence of plasma in front of the implant. It can be concluded from this study that the reported laser fluence and gas ambiences can effectively be applied for enhancing the titanium implant roughness and creation of titanium oxides and nitrides on the strictly localized surface area. The appearance of plasma in front of the implants indicates relatively high temperatures created above the surface. This offers a sterilizing effect, facilitating contaminant-free conditions.

  18. Energy balance in high-power CO2 laser welding

    Science.gov (United States)

    Del Bello, Umberto; Rivela, Cristina; Cantello, Maichi; Penasa, Mauro

    1991-10-01

    The laser energy impinging on a metal workpiece is partially absorbed and partially reflected by the material surface. This work is aimed at gaining a better insight into the energy balance of the process, and it can also provide the correct input for process modeling and the optimum choice of parameters for increasing welding efficiency. Measurements of the absorption coefficient were made using platinum-platinum rhodium thermocouples which monitored the temperature rise. The radiation backscattered by the workpiece or plasma plume was also recorded, and tests were performed to measure the total amount of material lost by evaporation during laser welding. All the tests were performed on austenitic stainless steel. The resulting absorption curves show different behavior at low or high speed and this can be explained only by taking into account the influence on the process of both the size and inclination of the keyhole. To conserve the keyhole, the interaction process must be rapidly interrupted so as to freeze the molten material and preserve the cavity in the form assumed during the process. A fast mechanical switch has been devised and tests seem to confirm the assumption made.

  19. CO2, Er: YAG and Nd:YAG lasers in endodontic surgery

    Directory of Open Access Journals (Sweden)

    Daniel Humberto Pozza

    2009-12-01

    Full Text Available OBJECTIVES: CO2, Er:YAG and Nd:YAG lasers have been used in endodontic surgery. This in vitro study evaluated 1% Rhodamine B dye penetration using computer-assisted morphometry (ImageTool Software® of 108 endodontically treated human permanent canines. MATERIAL AND METHODS: Teeth were divided into 9 groups according to the technique used: A: 90-degree apicoectomy with bur, root-end cavity preparation with ultrasound and filled with MTA; B: 90-degree apicoectomy with bur, root-end cavity prepared with ultrasound and filled with MTA, and treatment of apical surface with CO2 laser (1 W, CW/CW; C: 90-degree apicoectomy with bur, and treatment of apical surface with Nd:YAG laser (150 mJ, 10 Hz; D: 90-degree apicoectomy with bur, and treatment of apical surface with CO2 laser,(1 W, CW/CW; E: apicoectomy with Er:YAG laser (400 mJ, 10 Hz, root-end cavity prepared with ultrasound and filled with MTA; F: apicoectomy with Er:YAG laser (400 mJ, 10 Hz and treatment of apical surface with Nd:YAG laser (150 mJ, 10Hz; G: apicoectomy with CO2 laser (5W, CW/SP, root-end cavity prepared with ultrasound and filled with MTA; H: irradiation of apical end with CO2 laser (1 W, CW/CW; I: irradiation of apical end with Nd:YAG laser (150 mJ, 10 Hz. RESULTS: Dye penetration was found in all specimens at different rates, the lowest penetration occurring in groups C (16.20%, B (17.24% and F (17.84%. CONCLUSIONS: Groups B, C and F represent the best technical sequences to perform endodontic surgery.

  20. Water Vapor Adsorption on Biomass Based Carbons under Post-Combustion CO2 Capture Conditions: Effect of Post-Treatment

    Directory of Open Access Journals (Sweden)

    Nausika Querejeta

    2016-05-01

    Full Text Available The effect of post-treatment upon the H2O adsorption performance of biomass-based carbons was studied under post-combustion CO2 capture conditions. Oxygen surface functionalities were partially replaced through heat treatment, acid washing, and wet impregnation with amines. The surface chemistry of the final carbon is strongly affected by the type of post-treatment: acid treatment introduces a greater amount of oxygen whereas it is substantially reduced after thermal treatment. The porous texture of the carbons is also influenced by post-treatment: the wider pore volume is somewhat reduced, while narrow microporosity remains unaltered only after acid treatment. Despite heat treatment leading to a reduction in the number of oxygen surface groups, water vapor adsorption was enhanced in the higher pressure range. On the other hand acid treatment and wet impregnation with amines reduce the total water vapor uptake thus being more suitable for post-combustion CO2 capture applications.

  1. Water Vapor Adsorption on Biomass Based Carbons under Post-Combustion CO2 Capture Conditions: Effect of Post-Treatment

    Science.gov (United States)

    Querejeta, Nausika; Plaza, Marta G.; Rubiera, Fernando; Pevida, Covadonga

    2016-01-01

    The effect of post-treatment upon the H2O adsorption performance of biomass-based carbons was studied under post-combustion CO2 capture conditions. Oxygen surface functionalities were partially replaced through heat treatment, acid washing, and wet impregnation with amines. The surface chemistry of the final carbon is strongly affected by the type of post-treatment: acid treatment introduces a greater amount of oxygen whereas it is substantially reduced after thermal treatment. The porous texture of the carbons is also influenced by post-treatment: the wider pore volume is somewhat reduced, while narrow microporosity remains unaltered only after acid treatment. Despite heat treatment leading to a reduction in the number of oxygen surface groups, water vapor adsorption was enhanced in the higher pressure range. On the other hand acid treatment and wet impregnation with amines reduce the total water vapor uptake thus being more suitable for post-combustion CO2 capture applications. PMID:28773488

  2. High power pulsed fiber laser development for Co2 space based dial system

    Science.gov (United States)

    Canat, Guillaume; Le Gouët, Julien; Lombard, Laurent; Bresson, Alexandre; Goular, Didier; Dolfi-Bouteyre, Agnès.; Duzellier, Sophie; Boivin, Denis; Nilsson, Johan; Sahu, Jayata; Bordais, Sylvain

    2017-11-01

    High energy fiber lasers emitting around 1579nm is seen as a possible technology for the laser unit of a spaceborn CO2 DIAL system. We are developing an all fiber system with the following expected performances: pulse energy of 260μJ, pulse duration 150ns, beam quality M2 laser stability 200 kHz. One of our main concerns has been the radiation induced attenuation mitigation. Various fiber compositions have been investigated.

  3. Effect of CO2 laser radiation on physiological tolerance of wheat seedlings exposed to chilling stress.

    Science.gov (United States)

    Chen, Yi-Ping; Jia, Jing-Fen; Yue, Ming

    2010-01-01

    To determine the effect of CO(2) laser pretreatment of wheat seeds on the physiological tolerance of seedlings to chilling stress, wheat seeds were exposed to CO(2) laser radiation for 300 s. After being cultivated for 48 h at 25 degrees C, the wheat seedlings were subjected to chilling stress for 24 h. Selected physiological and biochemical parameters were measured in 6-day-old seedlings. We observed that chilling stress enhanced the concentrations of malondialdehyde and oxidized glutathione while decreasing the activities of nitric oxide synthase, catalase, peroxidase, superoxide dismutase and the concentrations of nitric oxide and glutathione in the wheat leaves compared with controls. When the chilling stress was preceded by CO(2) laser irradiation, the concentrations of malondialdehyde and oxidized glutathione were decreased while the activities of nitric oxide synthase, catalase, peroxidase, superoxide dismutase and the concentrations of nitric oxide and glutathione increased. Furthermore, chilling stress decreased the biomass, biophoton intensity and GHS/GSSG ratios of seedlings while these parameters increased when the seedlings were treated with CO(2) laser irradiation prior to the chilling stress. The results suggest that a suitable dose of CO(2) laser stimulation can enhance the physiological tolerance of wheat seedlings to chilling stress.

  4. Effect Of Nd:YAG laser and CO2 laser treatment on the resin bond strength to zirconia ceramic.

    Science.gov (United States)

    Paranhos, Maria Paula Gandolfi; Burnett, Luiz Henrique; Magne, Pascal

    2011-01-01

    this study evaluated the effect of surface treatments (Nd:YAG laser, CO2 laser, Al203 airborne-particle abrasion, and silica-coating) on the zirconia-to-resin shear bond strength (SBS). eighty-one Lava (3M ESPE) blocks (13 x 4 x 2 mm) were embedded in acrylic resin, polished, and randomly divided into three groups, which received the following surface treatments: no abrasion, Al203 airborne-particle abrasion (50 Μm), or silica-coating (Cojet, 3M ESPE). Each group was divided into three subgroups that were treated with Nd:YAG laser, CO2 laser, or no laser irradiation. Following application of a monomer phosphate-containing primer, cylinders of resin cement (Panavia F, Kuraray) (n = 18) were built on the surface. SBS testing was carried out after 24 hours of storage in water. Surface roughness and topography (SEM) after treatments were evaluated. according to ANOVA and Tukey test ( α = 0.05), mean SBS after Nd:YAG laser treatment ranged from 14.09 to 16.20 MPa and was statistically higher than CO2 laser (6.24 to 10.51 MPa) and no laser treatment (4.65 to 8.79 MPa). The Nd:YAG laser created more roughness on zirconia when compared to the CO2 laser and abrasion treatments. Silica-coating increased the SBS of lased and nonlased zirconia. Significant microcracks were found on specimens treated with CO2. Nd:YAG laser pretreatment, whether associated with abrasion methods or not, created consistent roughness on the zirconia surface and significantly increased zirconia SBS to Panavia F. Silica-coating could potentially increase the SBS of lased and nonlased zirconia. Significant microcracks were found on specimens treated with the CO2 laser.

  5. Depth of morphologic skin damage and viability after one, two, and three passes of a high-energy, short-pulse CO2 laser (Tru-Pulse) in pig skin.

    Science.gov (United States)

    Smith, K J; Skelton, H G; Graham, J S; Hamilton, T A; Hackley, B E; Hurst, C G

    1997-08-01

    CO2 laser energy is absorbed by water, which is present in all tissue. The depth of penetration of CO2 lasers is narrow with minimal reflection, scatter, or transmission. However, thermal damage has limited the usefulness of conventional, continuous-wave CO2 lasers for debridement as demonstrated by wound healing studies. The development of high-energy CO2 lasers, with pulse durations that are less than the thermal relaxation time of tissue, have made vaporization of skin for resurfacing and wound debridement possible because of the decreased risk of thermal damage. This study was performed to evaluate thermal damage produced by a CO2 laser. Routine histopathologic examination and nitroblue-tetrazolium chloride (NBTC) staining were used to evaluate the depth of tissue damage and viability in weanling pig skin after one, two, and three passes of the laser. At a pulse energy of 300 mJ, with a pulse duration of 60 microseconds, one pass of the laser produced vaporization of the epidermis with minimal thermal damage. Two passes produced areas of denatured collagen with loss of viable cells in the superficial papillary dermis. Three passes extended the damage into the papillary dermis. Hyalinization of collagen appears to correspond well with the level of thermal damage as measured by NBTC staining. Our findings suggest that the energy necessary to vaporize the dermis may be greater than that needed to vaporize epidermis.

  6. [Evaluation of the use of the CO2 laser in 134 patients with expansive processes in the central nervous system].

    Science.gov (United States)

    Lovrić, D; Negovetić, L; Lupret, V; Vidović, D; Gnjidić, Z

    1989-01-01

    The laser began to be used in neurosurgery towards the end of the 60s. The early experience of their clinical use did not promise much; but from the first half of the 70s with the improvement of the laser and the accumulation of laboratory and clinical experiences, the new technology began irrepressibly to spread throughout the world. Three lasers are in use today: CO2, ND.YAG and Argon laser. Each one of them, due to their different wave length and electromagnetic radiation, gave separate characteristics of employment, i.e., the interaction between the biologic tissues and the radiation is different. Depending upon the type of intraoperative needs we will choose one of the lasers. Presently the CO2-laser is the most used in neurosurgery due to its characteristics of low penetration into the tissue and the vaporization of the tissue which is exposed to the radiation. That is why such a laser (Sharplan 1060) has been acquired by our clinic. During one year we performed 134 operations due to expansive processes in the CNS with a partial or complete use of the laser during every phase of the operation. The accumulated experiences showed that the laser is a fairly useful new tool during the various surgical situations with a wide use of the everyday work of the neurosurgeon; with its implementation we have significantly improved the surgical technique in the tumors of the CNS, both in terms of radicality as well as in sparing the healthy tissue. We believe that the laser has an absolute indication in all the glioma tumors regardless of the localization, thereafter in all remaining tumors which are not extremely supplied by blood, while at the same time reducing the time needed for the surgical procedure. In time we spread the use of the laser on arteriovenous malformations as well, which, until now, has not been suggested in literature. Our results on 4 smaller superficial angiomas fully justified the use of a laser in such cases. But it also showed us that generally

  7. Complications in CO2 Laser Transoral Microsurgery for Larynx Carcinomas

    Directory of Open Access Journals (Sweden)

    Estomba, Carlos Miguel Chiesa

    2016-01-01

    Full Text Available Introduction Transoral laser microsurgery (TLM has established itself as an effective option in the management of malignant tumors of the glottis, supraglottis, and hypopharynx. Nonetheless, TLM is not a harmless technique. Complications such as bleeding, dyspnea, or ignition of the air may appear in this type of surgery. Objective The aim of this study is to describe the complications that occurred in a group of patients treated for glottic and supraglottic carcinomas in all stages by TLM. Methods This study is a retrospective analysis of patients diagnosed with squamous cell carcinoma of the glottis and supraglottis for all stages (T1, T2, T3, T4, N -/ + , M -/+ treated with TLM between January 2009 and March 2012 in a tertiary hospital. Results Ninety-eight patients met the inclusion criteria, which had undergone a total of 131 interventions. Ninety-four (95.9% patients were male and 4 (4.1% were female. The mean age was 64.2 years (± 10.7 years = min 45; max 88. The presence of intraoperative complications was low, affecting only 2% of patients. Immediate postoperative complications occurred in 6.1%, whereas delayed complications affected 13.2% of patients, without any of them being fatal. Conclusion TLM has shown good oncologic results and low complication rate compared with traditional open surgery during intervention, in the immediate and delayed postoperative period and in the long-term with respect to radiotherapy.

  8. Comparison of KTP, Thulium, and CO2 laser in stapedotomy using specialized visualization techniques: thermal effects.

    Science.gov (United States)

    Kamalski, Digna M A; Verdaasdonk, Rudolf M; de Boorder, Tjeerd; Vincent, Robert; Trabelzini, Franco; Grolman, Wilko

    2014-06-01

    High-speed thermal imaging enables visualization of heating of the vestibule during laser-assisted stapedotomy, comparing KTP, CO2, and Thulium laser light. Perforation of the stapes footplate with laser bears the risk of heating of the inner ear fluids. The amount of heating depends on absorption of the laser light and subsequent tissue ablation. The ablation of the footplate is driven by strong water absorption for the CO2 and Thulium laser. For the KTP laser wavelength, ablation is driven by carbonization of the footplate and it might penetrate deep into the inner ear without absorption in water. The thermal effects were visualized in an inner ear model, using two new techniques: (1) high-speed Schlieren imaging shows relative dynamic changes of temperatures up to 2 ms resolution in the perilymph. (2) Thermo imaging provides absolute temperature measurements around the footplate up to 40 ms resolution. The high-speed Schlieren imaging showed minimal heating using the KTP laser. Both CO2 and Thulium laser showed heating below the footplate. Thulium laser wavelength generated heating up to 0.6 mm depth. This was confirmed with thermal imaging, showing a rise of temperature of 4.7 (±3.5) °C for KTP and 9.4 (±6.9) for Thulium in the area of 2 mm below the footplate. For stapedotomy, the Thulium and CO2 laser show more extended thermal effects compared to KTP. High-speed Schlieren imaging and thermal imaging are complimentary techniques to study lasers thermal effects in tissue.

  9. Advanced concepts for high-power, short-pulse CO2 laser development

    Science.gov (United States)

    Gordon, Daniel F.; Hasson, Victor; von Bergmann, Hubertus; Chen, Yu-hsin; Schmitt-Sody, A.; Penano, Joseph R.

    2016-06-01

    Ultra-short pulse lasers are dominated by solid-state technology, which typically operates in the near-infrared. Efforts to extend this technology to longer wavelengths are meeting with some success, but the trend remains that longer wavelengths correlate with greatly reduced power. The carbon dioxide (CO2) laser is capable of delivering high energy, 10 micron wavelength pulses, but the gain structure makes operating in the ultra-short pulse regime difficult. The Naval Research Laboratory and Air Force Research Laboratory are developing a novel CO2 laser designed to deliver ~1 Joule, ~1 picosecond pulses, from a compact gain volume (~2x2x80 cm). The design is based on injection seeding an unstable resonator, in order to achieve high energy extraction efficiency, and to take advantage of power broadening. The unstable resonator is seeded by a solid state front end, pumped by a custom built titanium sapphire laser matched to the CO2 laser bandwidth. In order to access a broader range of mid infrared wavelengths using CO2 lasers, one must consider nonlinear frequency multiplication, which is non-trivial due to the bandwidth of the 10 micron radiation.

  10. Reduction in lateral thermal damage using heat-conducting templates: a comparison of continuous wave and pulsed CO2 lasers.

    Science.gov (United States)

    Spector, Nicole; Spector, Jared; Ellis, Darrel L; Reinisch, Lou

    2003-01-01

    The advantages of the continuous wave (c.w.) CO(2) laser are offset by the delay in laser wound healing secondary to thermal damage. We have developed novel heat-conducting templates to reduce laser thermal damage. Because shortened pulse durations also decrease thermal damage, we tested the effectiveness of heat-conducting templates with a c.w. CO(2) clinical laser and a short-pulsed CO(2) laser to determine the best method and mechanism to minimize thermal damage. Comparison of 0.2-second shuttered c.w. and 5-microsecond pulsed CO(2) lasers were made by doing incisions on 150 tissue samples from reduction mammoplasties and abdominoplasties. Copper, aluminum, glass, and Plexiglass heat-conducting templates were tested against no template (air) with both lasers. Histological samples were evaluated using computerized morphometrics analysis. Statistically significant reductions in lateral thermal damage were seen with the copper (50%) and aluminum (39%) templates used with the c.w. CO(2) laser. Only the copper template (39%) significantly reduced thermal damage when used with the pulsed CO(2) laser. Less thermal damage was seen using the pulsed CO(2) laser compared to the c.w. CO(2) laser with each template. Heat-conducting templates significantly reduced the amount of lateral thermal damage when used with the c.w. CO(2) laser (copper and aluminum) and short-pulsed CO(2) laser (copper). The c.w. CO(2) laser with the copper template compared favorably to the short-pulsed CO(2) laser without a template. Therefore, both heat conductive templates and short-pulse structure provide successful methods for reducing lateral thermal damage, and a combination of the two appears to provide optimal results.

  11. A 490 W transversely excited atmospheric CO2 spark gap laser with added H2

    Science.gov (United States)

    Zand, M.; Koushki, A. M.; Neshati, R.; Kia, B.; Khorasani, K.

    2018-02-01

    In this paper we present a new design for a high pulse repetition rate transversely excited atmospheric CO2 laser with ultraviolet pre-ionization. A new method of fast thyristor capacitor charging and discharging by a spark gap is used. The effect of H2 gas addition on the output and stability of a transversely excited atmospheric laser operating with a basic mixture of CO2, N2 and He is investigated. The output power was increased by adding H2 to the gas mixture ratio of CO2:N2:He:H2  =  1:1:8:0.5 at total pressure of 850 mbar. An average power of 490 W at 110 Hz with 4.5 J per pulse was obtained. The laser efficiency was 11.2% and oxygen gas was used in the spark gap for electron capture to reduce the recovery time and increase the repetition rate.

  12. Nonpenetrating glaucoma surgery using the CO2 laser: experimental studies in human cadaver eyes

    Science.gov (United States)

    Assia, Ehud I.; Barequet, Irina S.; Rosner, Mordechai; Belkin, Michael

    2001-06-01

    Non-penetrating trabeculectomy (NPT) is a potential replacement to conventional trabeculectomy, as it eliminates the necessity of penetrating the eye which is the cause of most of the complications entailed by the latter operation. NPT however, requires considerable surgical skill, is time consuming and entails complications of its own. We have shown that it can be easily performed by using the CO2 laser to ablate the sclera and corneoscleral tissues to the required depth. The use of the CO2 laser eliminates the danger of inadvertent perforation, a common complication of NPT as the tissue ablation ceases when the end-point of the operation, the aqueous humor percolation, is reached. Our experiments, performed on animal and human cadaver eyes showed that CO2 laser NPT rapid is easily mastered and performed rapid and eliminates almost completely the risk of complications.

  13. High quality electron bunch generation with CO2-laser plasma accelerator

    CERN Document Server

    Zhang, L G; Xu, J C; Ji, L L; Zhang, X M; Wang, W P; Zhao, X Y; Yi, L Q; Yu, Y H; Shi, Y; Xu, T J; Xu, Z Z

    2014-01-01

    CO2 laser-driven electron acceleration is demonstrated with particle-in-cell simulation in low-density plasma. An intense CO2 laser pulse with long wavelength excites wakefield. The bubble behind it has a broad space to sustain a large amount of electrons before reaching its charge saturation limit. A transversely propagating inject pulse is used to induce and control the ambient electron injection. The accelerated electron bunch with total charge up to 10 nC and the average charge per energy interval of more than 0.6 nC/MeV are obtained. Plasma-based electron acceleration driven by intense CO2 laser provides a new potential way to generate high-charge electron bunch with low energy spread, which has broad applications, especially for X-ray generation by table-top FEL and bremsstrahlung.

  14. A sulfur hexafluoride sensor using quantum cascade and CO2 laser-based photoacoustic spectroscopy.

    Science.gov (United States)

    Rocha, Mila; Sthel, Marcelo; Lima, Guilherme; da Silva, Marcelo; Schramm, Delson; Miklós, András; Vargas, Helion

    2010-01-01

    The increase in greenhouse gas emissions is a serious environmental problem and has stimulated the scientific community to pay attention to the need for detection and monitoring of gases released into the atmosphere. In this regard, the development of sensitive and selective gas sensors has been the subject of several research programs. An important greenhouse gas is sulphur hexafluoride, an almost non-reactive gas widely employed in industrial processes worldwide. Indeed it is estimated that it has a radiative forcing of 0.52 W/m(2). This work compares two photoacoustic spectrometers, one coupled to a CO(2) laser and another one coupled to a Quantum Cascade (QC) laser, for the detection of SF(6). The laser photoacoustic spectrometers described in this work have been developed for gas detection at small concentrations. Detection limits of 20 ppbv for CO(2) laser and 50 ppbv for quantum cascade laser were obtained.

  15. A clinical efficacy of using CO2 laser irradiating to transparent gel on aphthous stomatitis patients

    Science.gov (United States)

    Trivibulwanich, Juthamanee; Pipithirunkarn, Naruemon; Danvirutai, Nawaporn

    2013-01-01

    Background and aims: Regarding the laser energy delivery with non-tissue alteration when irradiating CO2 laser to the transparent gel, it was worth exploring the clinical efficacy of pain relief on oral ulceration using aphthous stomatitis as a model for painful oral ulcer. The aims of this study were to compare pain scores, daily activity-disturbance scores and sizes of the ulcers between the laser group and the placebo group. Subjects and methods: The double blind- randomized- placebo- controlled trial was conducted in 14 patients with aphthous ulcers. The subjects were allocated into 2 groups; namely, the laser group and the placebo group. The two baselines were measured on the day before and the treatment day. Then the lesions were covered with the transparent gel and irradiated by either 2 W defocused CO2 laser for 5 seconds or the sham laser. The outcomes were collected immediately, on day 1, 3, 5 and 7 after treatment. Results: The means of pain and daily activity-disturbance scores of the laser group were lesser than the placebo group in every episode. A statistically significant difference between the groups was found only the pain score on day 3 after treatment (P-value 0.05). Conclusion: The CO2 laser therapy used in this clinical study was able to relieve pain from aphthous stomatitis compared with the placebo on the day 3 after treatment. PMID:24511206

  16. Pulsed Laser Propulsion Performance of 11-cm Parabolic `Bell' Engines: CO2 TEA vs. EDL

    Science.gov (United States)

    Mori, Koichi; Sasoh, Akihiro; Myrabo, Leik N.

    2006-05-01

    Single pulse laboratory experiments were carried out with a high-power CO2 Transversely-Excited Atmospheric (TEA) laser using three laser pulsejet engines, shaped as parabolic bells, measuring 11-cm in diameter. Assuming the vertex is set at the parabola's focus, the "calibration bell" engines had three different total divergence angles of 60, 87.2, and 120 degrees (i.e., viewing outward towards the 11-cm nozzle exit plane). The objective was to quantify and calibrate the effects of laser pulse duration upon the momentum coupling coefficient (Cm) performance from the two CO2 lasers, using laser pulse energy as the parametric variable. Bell engine performance data from the TEA laser are contrasted with former results from the PLVTS CO2 electron discharge laser (EDL). The single-pulse PLVTS tests were conducted in Sept. 2000 and Sept. 2001, revealing that the impulse and Cm performance of the 60° bell generally exceeded the 87.2° engine, which in turn outperformed the 120° bell. With PLVTS, the maximum single-pulse Cm varied from 275 to 375 N-sec/MJ. In contrast, the 2 microsecond TEA laser tests generated results that were distinctively different from that of the EDL. Both tests used a standard ballistic pendulum to measure airbreathing engine performance at a pressure of one atmosphere.

  17. Effect of pretreatment on the incidence of hyperpigmentation following cutaneous CO2 laser resurfacing.

    Science.gov (United States)

    West, T B; Alster, T S

    1999-01-01

    Transient hyperpigmentation is the most common complication seen following cutaneous carbon dioxide (CO2) laser resurfacing. The purpose of this study was to determine whether the use of a topical skin lightening regimen prior to cutaneous laser resurfacing reduces the incidence of post-laser resurfacing hyperpigmentation. One hundred consecutive CO2 laser resurfacing patients (skin types I-III) were randomized to receive preoperative treatment with 10% glycolic acid cream twice daily (n=25), hydroquinone 4% cream qHS and tretinoin 0.025% cream twice daily (n=25) or no pretreatment (n=50, control) for at least 2 weeks. Clinical and photographic assessments were performed prior to laser resurfacing and at 4 and 12 weeks following treatment. There was no significant difference in the incidence of post-CO2 laser resurfacing hyperpigmentation between subjects who received pretreatment with either topical glycolic acid cream or combination tretinoin/hydroquinone creams and those who received no pretreatment regimen. It is postulated that reepithelialization after cutaneous laser resurfacing includes follicular melanocytes that have not been affected by topical pretreatment. When instituted as a component of the skin care regimen postoperatively, topical hydroquinone, tretinoin and/or glycolic acid preparations may be helpful in reducing post-laser resurfacing hyperpigmentation.

  18. Multi-criteria optimization in CO2 laser ablation of multimode polymer waveguides

    Science.gov (United States)

    Tamrin, K. F.; Zakariyah, S. S.; Sheikh, N. A.

    2015-12-01

    High interconnection density associated with current electronics products poses certain challenges in designing circuit boards. Methods, including laser-assisted microvia drilling and surface mount technologies for example, are being used to minimize the impacts of the problems. However, the bottleneck is significantly pronounced at bit data rates above 10 Gbit/s where losses, especially those due to crosstalk, become high. One solution is optical interconnections (OI) based on polymer waveguides. Laser ablation of the optical waveguides is viewed as a very compatible technique with ultraviolet laser sources, such as excimer and UV Nd:YAG lasers, being used due to their photochemical nature and minimal thermal effect when they interact with optical materials. In this paper, the authors demonstrate the application of grey relational analysis to determine the optimized processing parameters concerning fabrication of multimode optical polymer waveguides by using infra-red 10.6 μm CO2 laser micromachining to etch acrylate-based photopolymer (Truemode™). CO2 laser micromachining offers a low cost and high speed fabrication route needed for high volume productions as the wavelength of CO2 lasers can couple well with a variety of polymer substrates. Based on the highest grey relational grade, the optimized processing parameters are determined at laser power of 3 W and scanning speed of 100 mm/s.

  19. Nonlinear guiding of picosecond CO2 laser pulses in atmosphere(Conference Presentation)

    Science.gov (United States)

    Tochitsky, Sergei

    2017-05-01

    During the last 20 years much attention has been given to the study of propagation of short intense laser pulses for which the peak power exceeds the critical power of self-focusing, Pcr. For a laser power P laser-ionized plasma result in the production of a high intensity laser filament in air within which a variety of nonlinear optical phenomena are observed. However, research in the 0.8-1 μm range so far has shown a fundamental limitation of guided energy to a few mJ transported within an 100 μm single channel. A long-wavelength, 0 10 μm CO2 laser is a promising candidate for nonlinear guiding because expected high Pcr values according to the modeling should allow for the increase of energy (and therefore power) in a self-guided beam from mJ (GW) to few Joules (TW). During the last decade a significant progress has been achieved in amplification of picosecond pulses to terawatt and recently to lasers open possibility for nonlinear propagation studies in an atmospheric window with high transmission. As a natural first step in a our program on picosecond CO2 laser filamentation, we have made first measurements of Kerr coefficients of air and air constituents around 10 μm. We also undertook direct measurements of n2 of air by analyzing nonlinear self-focusing in air using a 3 ps, 600 GW pulses of the BNL CO2 laser.

  20. Management of infantile subglottic hemangioma: Laser vaporization, submucous resection, intubation, or intralesional steroids?

    NARCIS (Netherlands)

    L.J. Hoeve (Hans); G.L.E. Küppers (G. L E); C.D.A. Verwoerd (Carel)

    1997-01-01

    textabstractThe infantile subglottic hemangioma can be treated in various ways. The results of the treatment used in the Sophia Children's Hospital, intralesional steroids and intubation (IS + I), are discussed and compared with the results of other current treatment methods: CO2 laser vaporization,

  1. Comparison of fiber delivered CO2laser and electrocautery in transoral robot assisted tongue base surgery.

    Science.gov (United States)

    Karaman, Murat; Gün, Taylan; Temelkuran, Burak; Aynacı, Engin; Kaya, Cem; Tekin, Ahmet Mahmut

    2017-05-01

    To compare intra-operative and post-operative effectiveness of fiber delivered CO 2 laser to monopolar electrocautery in robot assisted tongue base surgery. Prospective non-randomized clinical study. Twenty moderate to severe obstructive sleep apnea (OSA) patients, non-compliant with Continuous Positive Airway Pressure (CPAP), underwent Transoral Robotic Surgery (TORS) using the Da Vinci surgical robot in our University Hospital. OSA was treated with monopolar electrocautery in 10 patients, and with flexible CO 2 laser fiber in another 10 patients. The following parameters in the two sets are analyzed: Intraoperative bleeding that required cauterization, robot operating time, need for tracheotomy, postoperative self-limiting bleeding, length of hospitalization, duration until start of oral intake, pre-operative and post-operative minimum arterial oxygen saturation, pre-operative and post-operative Epworth Sleepiness Scale score, postoperative airway complication and postoperative pain. Mean follow-up was 12 months. None of the patients required tracheotomy and there were no intraoperative complications related to the use of the robot or the CO 2 laser. The use of CO 2 laser in TORS-assisted tongue base surgery resulted in less intraoperative bleeding that required cauterization, shorter robot operating time, shorter length of hospitalization, shorter duration until start of oral intake and less postoperative pain, when compared to electrocautery. Postoperative apnea-hypopnea index scores showed better efficacy of CO 2 laser than electrocautery. Comparison of postoperative airway complication rates and Epworth sleepiness scale scores were found to be statistically insignificant between the two groups. The use of CO 2 laser in robot assisted tongue base surgery has various intraoperative and post-operative advantages when compared to monopolar electrocautery.

  2. Fabrication of microchannels on PMMA using a low power CO2 laser

    Science.gov (United States)

    Imran, Muhammad; Rahman, Rosly A.; Ahmad, Mukhtar; Akhtar, Majid N.; Usman, Arslan; Sattar, Abdul

    2016-09-01

    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.

  3. Spectroscopic measurements of laser induced plasma during welding with CO2 laser

    Science.gov (United States)

    Szymanski, Z.; Kurzyna, J.

    1994-12-01

    Results of spectroscopic measurements of laser-induced plasma under welding conditions are presented. Welding was performed with the use of a continuous-wave CO2 laser operating at a power of 2 kW. Argon or helium was used as a shielding gas. The welding metal was stainless steel or titanium. Emission spectra from plasma were measured with a spectrograph and 1254 Silicon Intensified Target (SIT) detector connected to the optical multichannel analyzer. The plasma electron temperatures were determined from the relative intensities of spectral lines and the electron densities were determined either from Stark broadening of atomic line or the absolute intensity of ionic line. The distributions of the electron temperature and density over the metal surface are presented and the influence of a shielding gas on plasma parameters is demonstrated. The plasma parameters obtained were used to calculate the absorption of a laser beam in the plasma over the metal surface. No significant absorption was found in our experimental conditions.

  4. New Medical Applications Of Metal Vapor Lasers

    Science.gov (United States)

    Anderson, Robert S.; McIntosh, Alexander I.

    1989-06-01

    The first medical application for metal vapor lasers has been granted marketing approval by the FDA. This represents a major milestone for this technology. Metalaser Technologies recently received this approval for its Vasculase unit in the treatment of vascular lesions such as port wine stains, facial telangiectasia and strawberry hemangiomas.

  5. Long-path absorption measurement of CO(2) with a Raman-shifted tunable dye laser.

    Science.gov (United States)

    Sugimoto, N; Minato, A

    1993-11-20

    A laser long-path absorption system was developed with a hydrogen Raman shifter pumped by a tunable dye laser. The absorption spectrum of CO(2) in the 2-µm region was measured in the open air with a retroreflector or a hard target. The concentration of CO(2) was determined from the spectrum by the least-squares method. Noise in the system was analyzed, and the propagation of error to the obtained concentration was investigated. The statistical error in the concentration was estimated at approximately 1% for a single spectrum measurement. Comparison with the simultaneous measurements with a nondispersive infrared gas analyzer showed good agreement.

  6. Effects of CO2 laser in treatment of cervical dentinal hypersensitivity.

    Science.gov (United States)

    Zhang, C; Matsumoto, K; Kimura, Y; Harashima, T; Takeda, F H; Zhou, H

    1998-09-01

    The effectiveness of CO2 laser therapy in the reduction and elimination of dentinal hypersensitivity in vivo and its thermal effects on tooth surfaces in vitro were investigated. Twenty-three patients with 91 sensitive teeth participated in this study and were followed for 3 months. The parameters used with CO2 laser were 1 W in a continuous wave mode and irradiation time ranging from 5 to 10 s. Hypersensitivity was assessed by thermal stimulus (a blast of air from a dental syringe). Thermal effects were measured by thermography using 10 extracted human teeth. After laser treatment, all patients were immediately free from sensitive pain. Over 3 months, the CO2 laser treatment reduced dentinal hypersensitivity to air stimulus by 50%. All teeth remained vital with no adverse effects. Thermography revealed no temperature increase on irradiated tooth surfaces subjected to water coolant. These results show that the CO2 laser is useful in the treatment of cervical dentinal hypersensitivity without thermal damage to pulp.

  7. Permeability of eroded enamel following application of different fluoride gels and CO2 laser.

    Science.gov (United States)

    Lepri, Taísa Penazzo; Colucci, Vivian; Turssi, Cecília Pedroso; Corona, Silmara Aparecida Milori

    2013-01-01

    This study evaluated the combined effect of fluoride compounds and CO(2) laser in controlling the permeability of eroded enamel. Bovine enamel slabs (3 × 2 mm) were cycled twice through an alternating erosion and remineralization regimen. Slabs were immersed in 20 ml of orange juice (pH 3.84) for 5 min under agitation, rinsed with deionized water, and stored in artificial saliva for 4 h to form erosive lesions. Specimens were then divided into four groups (n = 10), which were treated for 1 min with either a control or with one of the following gels: amine fluoride (AmF), titanium tetrafluoride (TiF(4)), or sodium fluoride (NaF). Half of the specimens were irradiated with a CO(2) laser (λ = 10.6 μm; 2.0 W). Specimens were cycled two more times through the aforementioned erosion-remineralization regimen and were subjected to permeability assessment. ANOVA demonstrated a significant interaction between fluoride and laser treatment (p = 0.0152). Tukey's test showed that when fluoride was applied alone, TiF(4) resulted in lower enamel permeability than that observed after application of the placebo gel. Intermediate permeability values were noted after NaF and AmF had been used. A significant reduction in enamel permeability was obtained when fluoride was combined with CO(2) laser treatment, with no difference between fluoride gels. Permeability of eroded enamel may be reduced by combining the application of fluoride gels with CO(2) laser irradiation.

  8. [Treatment of giant congenital nevus with high-energy pulsed CO2 laser].

    Science.gov (United States)

    Michel, J L; Caillet-Chomel, L

    2001-11-01

    All authors agree upon the need for early treatment of giant congenital nevi. The surgeon must seek to minimize the risk of malignancy. The objective calls for radical excision of all pigmented areas; this may be impossible because of the risk of leaving the patient with disfiguring scars. The aim of this study was to assess treatment of giant congenital nevi with the high-energy pulsed CO2 laser as an alternative to surgery. Between 1998 and 1999, the high-energy pulsed CO2 laser was used in nine newborns and five children. The treatment with the high-energy pulsed CO2 laser achieved 70-90% clearing of the giant nevi in most of the children. Two children developed hypertrophic scars on a companion nevi and on giant congenital nevi. One child required a skin graft because of tissue necrosis, associated with a disseminated intravascular coagulation and septic shock. Laser is a surface technique proposed when surgical excision cannot be performed because the surface is too large or the localization is incompatible with surgery. Early treatment, in the first 15 days, is not required for the quality of the cosmetic result. The high-energy pulsed CO2 laser provides satisfactory cosmetic results with short cicatrisation time. It allows the treatment of the companion nevi at the same time. The risk of malignant transformation is greatly but not totally reduced. Regular clinical surveillance should help reduce the risk.

  9. Fractional CO2laser versus intense pulsed light in treating striae distensae

    Directory of Open Access Journals (Sweden)

    Moustafa Adam El Taieb

    2016-01-01

    Full Text Available Context: Striae distensae are linear atrophic dermal scars covered with flat atrophic epidermis. They may cause disfigurement, especially in females. Many factors may cause striae distensae such as steroids, obesity, and pregnancy. Although there is no standard treatment for striae; many topical applications, peeling, and light and laser systems have been tried. Aims: To evaluate and compare the efficacy of fractional CO2laser with intense pulse light in treating striae distensae. Subjects and Methods: Forty patients with striae distensae were recruited. Twenty of them were treated by fractional CO2laser and 20 were treated with intense pulse light. Length and width of the largest striae were measured pre- and post-treatment. Patient satisfaction was also evaluated and graded. Patients were photographed after each treatment session and photos were examined by a blinded physician who had no knowledge about the cases. Results: Both groups showed significant improvement after treatments (P 0.05. Conclusions: The current study has provided supportive evidence to the effectiveness of both fractional CO2laser and intense pulse light as treatments for striae distensae. Fractional CO2laser was found to be more effective in the treatment of striae distensae compared with intense pulse light.

  10. Fractional CO2 Laser Versus Intense Pulsed Light in Treating Striae Distensae.

    Science.gov (United States)

    El Taieb, Moustafa Adam; Ibrahim, Ahmed Khair

    2016-01-01

    Striae distensae are linear atrophic dermal scars covered with flat atrophic epidermis. They may cause disfigurement, especially in females. Many factors may cause striae distensae such as steroids, obesity, and pregnancy. Although there is no standard treatment for striae; many topical applications, peeling, and light and laser systems have been tried. To evaluate and compare the efficacy of fractional CO2 laser with intense pulse light in treating striae distensae. Forty patients with striae distensae were recruited. Twenty of them were treated by fractional CO2 laser and 20 were treated with intense pulse light. Length and width of the largest striae were measured pre- and post-treatment. Patient satisfaction was also evaluated and graded. Patients were photographed after each treatment session and photos were examined by a blinded physician who had no knowledge about the cases. Both groups showed significant improvement after treatments (P 0.05). The current study has provided supportive evidence to the effectiveness of both fractional CO2 laser and intense pulse light as treatments for striae distensae. Fractional CO2 laser was found to be more effective in the treatment of striae distensae compared with intense pulse light.

  11. Advances in High Energy Solid-State Pulsed 2-Micron Lidar Development for Ground and Airborne Wind, Water Vapor and CO2 Measurements

    Science.gov (United States)

    Singh, Upendra N.; Yu, Jirong; Petros, Mulugeta; Refaat, Tamer; Kavaya, Michael J.; Remus, Ruben

    2015-01-01

    triple-pulsed 2-micron Integrated Differential Absorption Lidar (IPDA) instrument for simultaneous measurement of water vapor and carbon-dioxide column density measurement from an air-borne platform. This presentation will give an overview of the 2 decades of 2-micron coherent and direction detection of laser/lidar development at NASA Langley Research Center and will present the ground and airborne wind and column CO2 measurement intercomparison with in-situ, balloon and flask measurements.

  12. Advances in High Energy Solid-State Pulsed 2-micron Lidar Development for Ground and Airborne Wind, Water Vapor and CO2 Measurements

    Science.gov (United States)

    Singh, Upendra; Yu, Jirong; Petros, Mulugeta; Refaat, Tamer; Kavaya, Michael; Remus, Ruben

    2015-04-01

    ) instrument for simultaneous measurement of water vapor and carbon-dioxide column density measurement from an air-borne platform. This presentation will give an overview of the 2 decades of 2 μm coherent and direction detection of laser/lidar development at NASA Langley Research Center and will present the ground and airborne wind and column CO2 measurement intercomparison with in-situ, balloon and flask measurements.

  13. Standard guidelines of care: CO 2 laser for removal of benign skin lesions and resurfacing

    Directory of Open Access Journals (Sweden)

    Krupashankar D

    2008-03-01

    Full Text Available Resurfacing is a treatment to remove acne and chicken pox scars, and changes in the skin due to ageing. Machines : Both ablative and nonablative lasers are available for use. CO 2 laser is the gold standard in ablative lasers. Detailed knowledge of the machines is essential. Indications for CO 2 laser: Therapeutic indications: Actinic and seborrheic keratosis, warts, moles, skin tags, epidermal and dermal nevi, vitiligo blister and punch grafting, rhinophyma, sebaceous hyperplasia, xanthelasma, syringomas, actinic cheilitis angiofibroma, scar treatment, keloid, skin cancer, neurofibroma and diffuse actinic keratoses. CO 2 laser is not recommended for the removal of tattoos. Aesthetic indications: Resurfacing for acne, chicken pox and surgical scars, periorbital and perioral wrinkles, photo ageing changes, facial resurfacing. Physicians′ qualifications: Any qualified dermatologist (DVD or MD may practice CO 2 laser. The dermatologist should possess postgraduate qualification in dermatology and should have had specific hands-on training in lasers either during postgraduation or later at a facility which routinely performs laser procedures under a competent dermatologist/plastic surgeon, who has experience and training in using lasers. For the use of CO 2 lasers for benign growths, a full day workshop is adequate. As parameters may vary in different machines, specific training with the available machine at either the manufacturer′s facility or at another centre using the machine is recommended. Facility: CO 2 lasers can be used in the dermatologist′s minor procedure room for the above indications. However, when used for full-face resurfacing, the hospital operation theatre or day care facility with immediate access to emergency medical care is essential. Smoke evacuator is mandatory. Preoperative counseling and Informed consent Detailed counseling with respect to the treatment, desired effects, possible postoperative complications, should be

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

    Science.gov (United States)

    Moradi, Mahmoud; Mehrabi, Omid; Azdast, Taher; Benyounis, Khaled Y.

    2017-11-01

    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 3.2 mm. 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.

  15. Raman spectroscopic studies of CO2 laser-irradiated human dental enamel

    Science.gov (United States)

    Aminzadeh, A.; Shahabi, S.; Walsh, L. J.

    1999-06-01

    While the effects of carbon dioxide (CO2) laser radiation on the physical properties of human dental enamel are well characterized, little is known regarding laser-induced chemical changes. In this study, enamel was exposed to CO2 laser radiation to induce fusion and recrystallization, and the Raman spectra recorded using both dispersive and Fourier-transformed (FT) Raman spectroscopy. Spectra were compared to a heat-treated specimen of hydroxyapatite (HAP) and enamel. Laser irradiation induced chemical changes which differed from those induced by heat treatment. Comparing the Raman spectra of lased enamel to HAP and tricalcium phosphate (TCP), it is evident that CO2 laser irradiation of enamel causes the partial conversion of HAP to TCP. The effect of laser irradiation is not merely a simple local heating effect as previously thought, since simple heating of enamel leads to the formation of both TCP and Ca(OH)2, while laser treatment of enamel results in the formation of TCP but not Ca(OH)2.

  16. Sensitive detection of CO2 implementing tunable thulium-doped all-fiber laser.

    Science.gov (United States)

    Bremer, K; Pal, A; Yao, S; Lewis, E; Sen, R; Sun, T; Grattan, K T V

    2013-06-10

    In this paper a compact, yet sensitive gas detection system based on a modulated, tunable thulium-doped fiber laser in the 2 μm wavelength region is reported. The laser operating wavelength range centered at a wavelength of 1.995 μm has been selected to access the R(50) transition (ν1+2ν2+ν3) of CO2 based on its line strength and to achieve isolation from interfering high-temperature water absorption features. The laser linewidth and tuning range are optimized accordingly. The modulation of the fiber laser, achieved through pump source modulation and a locking detection mechanism, has been utilized to stabilize the laser system and therefore to create a compact gas sensor with high sensitivity. The absorption spectrum, as well as the line strength and the concentration level of CO2, have been monitored through absorption spectroscopy techniques. The measured minimum detectable concentration of CO2 obtained using the system shows that it is quite capable of detecting trace gas at the ppm (parts in 10(6)) level. The stable laser performance achieved in the sensor system illustrates its potential for the development of practical, compact, yet sensitive fiber-laser-based gas sensor systems.

  17. Study on Interactions of Continuous Low Power CO2 Laser with Malaysian Molar Teeth

    Science.gov (United States)

    Ahmad, A. L.; Jaafar, M. S.; Ramzun, M. R.; Bermakai, M. Yahaya; Ismail, N. E.; Houssien, Hend A. A.

    2010-07-01

    Recent studies have shown that CO2 lasers can successfully be used at low-energy densities in dentistry. The CO2 laser is effective for a dental hard tissue since it strongly absorbs light in certain regions of the infrared spectrum because of the carbonate and hydroxyl groups in the structure. In this study, nineteen samples of molars extracted human teeth were irradiated with low power CO2 laser. Laser power of 3W, 6W, 9W, 12W, 15W and 18W, with exposure time of 5 s and 10 s, and distance between laser aperture and sample of 4 cm were used. Laser power above 18W is seen to damage the teeth. The teeth compositions were analyzed using the Fourier Transform Infrared Spectroscopy (FTIR). High laser power caused higher reflectance of the beam because the increased in temperature increasing the rate of chemical reaction, hence, the products after the irradiation. This situation can be explained by the Arrhenius equation [1].

  18. Growth CO2 concentration modifies the transpiration response of Populus deltoides to drought and vapor pressure deficit.

    Science.gov (United States)

    Engel, Victor C; Griffin, Kevin L; Murthy, Ramesh; Patterson, Lane; Klimas, Christie; Potosnak, Mark

    2004-10-01

    Cottonwood (Populus deltoides Bartr. ex Marsh.) trees grown for 9 months in elevated carbon dioxide concentration ([CO2]) showed significant increases in height, leaf area and basal diameter relative to trees in a near-ambient [CO2] control treatment. Sample trees in the CO2 treatments were subjected to high and low atmospheric vapor pressure deficits (VPD) over a 5-week period at both high and low soil water contents (SWC). During these periods, transpiration rates at both the leaf and canopy levels were calculated based on sap flow measurements and leaf-to-sapwood area ratios. Leaf-level transpiration rates were approximately equivalent across [CO2] treatments when soil water was not limiting. In contrast, during drought stress, canopy-level transpiration rates were approximately equivalent across [CO2] treatments, indicating that leaf-level fluxes during drought stress were reduced in elevated [CO2] by a factor equal to the leaf area ratio of the two canopies. The shift from equivalent leaf-level transpiration to equivalent canopy-level transpiration with increasing drought stress suggests maximum water use rates were controlled primarily by atmospheric demand at high SWC and by soil water availability at low SWC. Changes in VPD had less effect on transpiration than changes in SWC for trees in both CO2 treatments. Transpiration rates of trees in both CO2 treatments reached maximum values at a VPD of about 2.0 kPa at high SWC, but leveled off and decreased slightly in both canopies as VPD increased above this value. At low SWC, increasing VPD from approximately 1.4 to 2.5 kPa caused transpiration rates to decline slightly in the canopies of trees in both treatments, with significant (P = 0.004) decreases occurring in trees in the near-ambient [CO2] treatment. The transpiration responses at high VPD in the presence of high SWC and throughout the low SWC treatment suggest some hydraulic limitations to water use occurred. Comparisons of midday leaf water potentials

  19. In Vitro Comparison of the Effects of Diode Laser and CO2 Laser on Topical Fluoride Uptake in Primary Teeth

    Directory of Open Access Journals (Sweden)

    Zahra Bahrololoomi

    2016-04-01

    Full Text Available Objectives: Fluoride therapy is important for control and prevention of dental caries. Laser irradiation can increase fluoride uptake especially when combined with topical fluoride application. The objective of this study was to compare the effects of CO2 and diode lasers on enamel fluoride uptake in primary teeth.Materials and Methods: Forty human primary molars were randomly assigned to four groups (n=10. The roots were removed and the crowns were sectioned mesiodistally into buccal and lingual halves as the experimental and control groups. All samples were treated with 5% sodium fluoride (NaF varnish. The experimental samples in the four groups were irradiated with 5 or 7W diode or 1 or 2W CO2 laser for 15 seconds and were compared with the controls in terms of fluoride uptake, which was determined using an ion selective electrode after acid dissolution of the specimens. Data were analyzed by SPSS version 16 using ANOVA treating the control measurements as covariates.Results: The estimated amount of fluoride uptake was 59.5± 16.31 ppm, 66.5± 14.9 ppm, 78.6± 12.43 ppm and 90.4± 11.51 ppm for 5W and 7 W diode and 1W and 2 W CO2 lasers, respectively, which were significantly greater than the values in the conventional topical fluoridation group (P<0.005. There were no significant differences between 7W diode laser and 1W CO2 laser, 5W and 7W diode laser, or 1W and 2W CO2 laser in this regard.Conclusion: The results showed that enamel surface irradiation by CO2 and diode lasers increases the fluoride uptake.

  20. Nitrogen/argon diluted acetylene and ethylene blue flames under infrared CO2 laser irradiation

    Directory of Open Access Journals (Sweden)

    Peter V. Pikhitsa

    2011-09-01

    Full Text Available We investigated changes in emission spectra from nitrogen/argon diluted laminar diffusion acetylene and ethylene blue flames irradiated by a powerful cw infrared CO2 laser. The changes in the radical emission bands can be interpreted as an indication of laser-induced decomposition of ethylene (for laser absorbing C2H4 fuel and of laser-absorbing intermediates (for non-absorbing C2H2 fuel. The results indicate that released active hydrogen plays an important role in addition/abstraction reactions without any participation of oxygen.

  1. Effective way to minimize the initial spike energy in a pulsed TE CO2 laser

    Science.gov (United States)

    Wu, Jin; Wang, Donglei; Wan, Chongyi; Liu, Shiming

    2009-01-01

    A novel method is provided in conventional TE CO2 laser configuration by utilizing a specially designed small capacitance in the UV preionization scheme and a carefully optimized pulser/sustainer discharge circuitry so that the initial spike energy in the laser pulse profile induced by gain-switch effect can be greatly reduced. An experimental illustration is given in which the initial spike energy in the laser pulse is suppressed to less than 3.5% of the total pulse energy while stable laser performance is maintained.

  2. ARTICLES: Physical laws governing the interaction of pulse-periodic CO2 laser radiation with metals

    Science.gov (United States)

    Vedenov, A. A.; Gladush, G. G.; Drobyazko, S. V.; Pavlovich, Yu V.; Senatorov, Yu M.

    1985-01-01

    It is shown theoretically and experimentally that the efficiency of welding metals with a pulse-periodic CO2 laser beam of low duty ratio, at low velocities, can exceed that of welding with cw lasers and with electron beams. For the first time an investigation was made of the influence of the laser radiation parameters (energy and frequency) and of the welding velocity on the characteristics of the weld and on the shape of the weldpool. The influence of the laser radiation polarization on the efficiency of deep penetration was analyzed.

  3. Laser Sounder for Measuring Atmospheric CO2 Concentrations: Progress Toward Ascends

    Science.gov (United States)

    Abshire, J. B.; Kawa, S. R.; Riris, H.; Allan, G. R.; Sun, X.; Stephen, M. A.; Wilson, E.; Burris, J. F.; Mao, J.

    2008-01-01

    The next generation of space-based, active remote sensing instruments for measurement of tropospheric CO2 promises a capability to quantify global carbon sources and sinks at regional scales. Active (laser) methods will extend CO2 measurement coverage in time, space, and perhaps precision such that the underlying mechanisms for carbon exchange at the surface can be understood with .sufficient detail to confidently project the future of carbon-climate interaction and the influence of remediative policy actions. The recent Decadal Survey for Earth Science by the US National Research Council has recommended such a mission called the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) for launch in 2013-2016. We have been developing a laser technique for measurement of tropospheric CO2 for a number of years. Our immediate goal is to develop and demonstrate the method and instrument technology that will permit measurements of the CO2 column abundance over a horizontal path and from aircraft at the few-ppmv level. Our longer-term goal is to demonstrate the required capabilities of the technique, develop a space mission approach, and design the instrument for an ASCENDS-type mission. Our approach is to use a dual channel laser absorption spectrometer (i.e., differential absorption in altimeter mode), which continuously measures from a near-polar circular orbit. We use several co-aligned tunable fiber laser transmitters allowing simultaneous measurement of the absorption from a CO2 line in the 1570 nm band, O2 extinction in the oxygen A-band (near 765 nm), and aerosol backscatter in the same measurement path. We measure the energy of the laser echoes at nadir reflected from land and water surfaces, day and night. The lasers have spectral widths much narrower than the gas absorption lines and are turned on and off the selected CO2 and O2 lines at kHz rates. The gas extinction and column densities for the CO2 and O2 gases are estimated from the ratio of

  4. Proton acceleration using doped Argon plasma density gradient interacting with relativistic CO2 -laser pulse

    Science.gov (United States)

    Sahai, Aakash; Ettlinger, Oliver; Hicks, George; Ditter, Emma-Jane; Najmudin, Zulfikar

    2016-10-01

    We investigate proton and light-ion acceleration driven by the interaction of relativistic CO2 laser pulses with overdense Argon or other heavy-ion gas targets doped with lighter-ion species. Optically shaping the gas targets allows tuning of the pre-plasma scale-length from a few to several laser wavelengths, allowing the laser to efficiently drive a propagating snowplow through the bunching in the electron density. Preliminary PIC-based modeling shows that the lighter-ion species is accelerated even without any significant motion of the heavier ions which is a signature of the Relativistically Induced Transparency Acceleration mechanism. Some outlines of possible experiments at the TW CO2 laser at the Accelerator Test Facility at Brookhaven National Laboratory are presented.

  5. [Laser vaporization of the prostate: all as it should be?].

    Science.gov (United States)

    Reich, O; Seitz, M

    2008-04-01

    Laser vaporization of the prostate currently occupies a prominent place among the surgical options for treatment of benign prostatic syndrome. Particularly the so-called GreenLight laser vaporization with the KTP (80 W) or LBO (120 W) laser has become remarkably widespread throughout the world. There are already 100 of these GreenLight laser systems in use in Germany alone. The introduction of a separate DRG for "laser vaporization" is expected to further increase the significance of this surgical technique. The aim of this study is to evaluate laser vaporization as a whole and to identify possible differences between the different lasers.

  6. Experimental set-up for a pulsed CO2 laser rangefinder with heterodyne detection

    Science.gov (United States)

    Bloem, J.

    1990-08-01

    The creation of a pulsed CO2 laser range finder with heterodyne detection is described. The range finder uses a hybrid CW-TEA (Continuous Wave-Transversely Excited Atmospheric pressure) laser as emitter and an RF laser as local oscillator. The laser stabilization is described. The frequency offset between the transmitted laser pulse and the local oscillator laser is locked at 20 MHz. The long term (20 to 30 min) variation of this offset frequency is limited to 50 kHz. The effects of pulsing on this stabilization were eliminated. The signal processing was started. A rough model of the laser pulse and its frequency characteristics was developed. An AM demodulator was developed to determine the envelope of the reflected pulses. The system created can be used to measure the range to (and in the future also the speed of) diffuse reflecting targets.

  7. Laser Sounder Approach for Measuring Atmospheric CO2 Concentrations for the ASCENDS Mission

    Science.gov (United States)

    Abshire, J. B.; Riris, H.; Allan, G. R.; Sun, X.; Wilson, E.; Stephen, M. A.; Weaver, C.

    2008-12-01

    Accurate measurements of tropospheric CO2 abundances with global-coverage and monthly temporal resolution are needed to quantify processes that regulate CO2 exchange with the land and oceans. To meet this need, the 2007 Decadal Survey for Earth Science by the US National Research Council recommended a laser-based CO2 measuring mission called ASCENDS. In July 2008 NASA convened a science definition workshop for ASCENDS, which helped better define the mission and measurement requirements. We have been developing a technique for the remote measurement of tropospheric CO2 concentrations from aircraft and spacecraft. Our immediate goal is to develop and demonstrate the lidar technique and technology that will permit measurements of the CO2 column abundance over horizontal paths and from aircraft at the few-ppmv level. Our longer-term goal is to demonstrate the capabilities of the technique and instrument design needed for an ASCENDS-type mission. Our approach uses the 1570-nm band and a dual channel laser absorption spectrometer (ie DIAL used in altimeter mode). It uses several tunable fiber laser transmitters allowing simultaneous measurement of the absorption from a CO2 absorption line in the 1570 nm band, O2 extinction in the oxygen A-band, and surface height and aerosol backscatter in the same path. It directs the narrow co-aligned laser beams toward nadir, and measures the energy of the laser echoes reflected from land and water surfaces. The lasers are tuned on and off the sides of CO2 line and an O2 line (near 765 nm) at kHz rates. The receiver uses a telescope and photon counting detectors, and measures the background light and energies of the laser echoes from the surface along with scattering from any aerosols in the path. The gas extinction and column densities for the CO2 and O2 gases are estimated from the ratio of the on and off line signals via the DIAL technique. We use pulsed laser signals and time gating to isolate the laser echo signals from the

  8. Compact, CO2-stabilized tuneable laser at 2.05 microns

    DEFF Research Database (Denmark)

    Westergaard, Philip G.; Thomsen, Jan W.; Henriksen, Martin Romme

    2016-01-01

    We demonstrate a compact fibre-based laser system at 2.05 microns stabilized to a CO2 transition using frequency modulation spectroscopy of a gas-filled hollow-core fibre. The laser exhibits an absolute frequency accuracy of 5 MHz, a frequency stability noise floor of better than 7 kHz or 5......×10−11 and is tunable within ±200 MHz from the molecular resonance frequency while retaining roughly this stability and accuracy....

  9. Development of tunable high pressure CO2 laser for lidar measurements of pollutants and wind velocities

    Science.gov (United States)

    Levine, J. S.; Guerra, M.; Javan, A.

    1980-01-01

    The problem of laser energy extraction at a tunable monochromatic frequency from an energetic high pressure CO2 pulsed laser plasma, for application to remote sensing of atmospheric pollutants by Differential Absorption Lidar (DIAL) and of wind velocities by Doppler Lidar, was investigated. The energy extraction principle analyzed is based on transient injection locking (TIL) at a tunable frequency. Several critical experiments for high gain power amplification by TIL are presented.

  10. Collisionless dissociation and isotopic enrichment of SF6 using high-powered CO2 laser radiation

    Science.gov (United States)

    Gower, M. C.; Billman, K. W.

    1977-01-01

    Dissociation of S-32F6 and the resultant isotopic enrichment of S-34F6 using high-powered CO2 laser radiation has been studied with higher experimental sensitivity than previously reported. Enrichment factors have been measured as a function of laser pulse number, wavelength, energy and time duration. A geometry independent dissociation cross section is introduced and measured values are presented. Threshold energy densities, below which no dissociation was observed, were also determined.

  11. CO2 laser application in gynecology: experience in microsurgery of cervical lesions

    Science.gov (United States)

    Knapp, Piotr A.

    1995-03-01

    A CO2 laser device was used for treating cervical lesions in 1574 patients. Of the total, 163 were diagnosed as CIN. Patients were selected for the study as a result of mass screening during the period from 1988 to 1992 of Bialystok Province, Poland. Treatment of cervical lesions with laser proved to be effective. In the author's opinion it is an essential step in preventing cervical malignancy.

  12. Fabrication of polystyrene microfluidic devices using a pulsed CO2 laser system

    KAUST Repository

    Li, Huawei

    2013-10-10

    In this article, we described a simple and rapid method for fabrication of droplet microfluidic devices on polystyrene substrate using a CO2 laser system. The effects of the laser power and the cutting speed on the depth, width and aspect ratio of the microchannels fabricated on polystyrene were investigated. The polystyrene microfluidic channels were encapsulated using a hot press bonding technique. The experimental results showed that both discrete droplets and laminar flows could be obtained in the device.

  13. Laser Sounder for Global Measurement of CO2 Concentrations in the Troposphere from Space

    Science.gov (United States)

    Abshire, James B.; Riris, Haris; Kawa, S. Randy; Sun, Xiaoli; Chen, Jeffrey; Stephen, Mark A.; Collatz, G. James; Mao, Jianping; Allan, Graham

    2007-01-01

    Measurements of tropospheric CO2 abundance with global-coverage, a few hundred km spatial and monthly temporal resolution are needed to quantify processes that regulate CO2 storage by the land and oceans. The Orbiting Carbon Observatory (OCO) is the first space mission focused on atmospheric CO2 for measuring total column CO, and O2 by detecting the spectral absorption in reflected sunlight. The OCO mission is an essential step, and will yield important new information about atmospheric CO2 distributions. However there are unavoidable limitations imposed by its measurement approach. These include best accuracy only during daytime at moderate to high sun angles, interference by cloud and aerosol scattering, and limited signal from CO2 variability in the lower tropospheric CO2 column. We have been developing a new laser-based technique for the remote measurement of the tropospheric CO2 concentrations from orbit. Our initial goal is to demonstrate a lidar technique and instrument technology that will permit measurements of the CO2 column abundance in the lower troposphere from aircraft. Our final goal is to develop a space instrument and mission approach for active measurements of the CO2 mixing ratio at the 1-2 ppmv level. Our technique is much less sensitive to cloud and atmospheric scattering conditions and would allow continuous measurements of CO2 mixing ratio in the lower troposphere from orbit over land and ocean surfaces during day and night. Our approach is to use the 1570nm CO2 band and a 3-channel laser absorption spectrometer (i.e. lidar used an altimeter mode), which continuously measures at nadir from a near polar circular orbit. The approach directs the narrow co-aligned laser beams from the instrument's lasers toward nadir, and measures the energy of the laser echoes reflected from land and water surfaces. It uses several tunable fiber laser transmitters which allowing measurement of the extinction from a single selected CO2 absorption line in the 1570

  14. Verruca plana as a complication of CO2 laser treatment: a case report.

    Science.gov (United States)

    Winn, Aubrey E; Kentosh, Joshua; Bingham, Jonathan L

    2015-04-01

    Carbon dioxide (CO2) laser treatment is a common therapeutic modality for many dermatologic conditions. It uses a high energy, infrared beam of light, which selectively targets water-containing tissue resulting in controlled ablative resurfacing. This modality, however, can manifest significant cosmetic side effects. Here we report a case of verruca plana manifesting as a response to CO2 laser treatment. A 74-year-old female with recent Mohs surgery for a basal cell carcinoma, presented for full-face-fractionated CO2 treatment to address her surgical scars in addition to treating her mild diffuse actinic damage. Six weeks post treatment, the patient developed erythematous thin plaques over the areas that had been treated. Histology was consistent with verruca plana. Lesions showed mild improvement with topical tretinoin. Verruca plana are benign and typically self-limited; however, they can present a significant cosmetic burden to patients and are an important complication to consider when performing elective cosmetic procedures.

  15. Aprimoramentos no transplante de cabelo com laser de CO2: apresentação de três casos clínicos Improvements in CO2 laser hair transplantation: presentation of three clinical cases

    Directory of Open Access Journals (Sweden)

    Cristina Mansur

    2004-04-01

    Full Text Available Os autores apresentam três casos de transplante de cabelo em que foram feitas incisões receptoras mistas: orifício com vaporização com laser de CO2 nos quais se adicionou uma incisão lateral a frio. Essa incisão lateral facilita a introdução dos microenxertos por permitir a saída do ar e melhora sua fixação por conferir elasticidade ao orifício. Os pacientes foram previamente betabloqueados para evitar o efeito beta da adrenalina.The authors present three hair transplantation cases in which the receptor incisions were made in a variety of ways: CO2 laser vaporization orifices, in addition to which a lateral cold incision was performed. This lateral incision makes it easier to introduce micrografts by allowing air to be released and improves the fixation of the grafts by giving some elasticity to the orifice. The patients were previously beta blocked to prevent the beta-adrenergic action of epinefrin.

  16. Post-operative morbidity and 1-year outcomes in CO2-laser tonsillotomy versus dissection tonsillectomy

    NARCIS (Netherlands)

    Lourijsen, Evelijn S.; Wong Chung, Justin E. R. E.; Koopman, Jan Pieter; Blom, Henk M.

    2016-01-01

    Objective: In this study a type of partial tonsil surgery, CO2-laser tonsillotomy, was compared to regular tonsillectomy. The effectiveness and post-operative recovery rate of both interventions in adult patients was assessed by using a questionnaire.Study design: Prospective follow-up

  17. Endoscopic treatment of pharyngeal pouches: electrocoagulation vs carbon dioxide (CO2) laser

    NARCIS (Netherlands)

    Flikweert, D. C.; van der Baan, S.

    1992-01-01

    Endoscopic treatment of a hypopharyngeal diverticulum was performed in 75 patients during the period 1976-1990. Initially electrocoagulation was used to divide the septum between the diverticulum and oesophagus. More recently, the CO2 laser combined with the operating microscope has been used.

  18. Treatment results of CO2 laser vaporisation in a cohort of 35 patients with oral leukoplakia

    NARCIS (Netherlands)

    Brouns, E.R.E.A.; Baart, J.A.; Karagozoglu, K.H.; Aartman, I.H.A.; Bloemena, E.; van der Waal, I.

    2013-01-01

    Objectives The aim of the present study was to evaluate the treatment results of CO2 laser vaporisation in a well-defined cohort of patients with oral leukoplakia (OL). Material and methods The group consisted of 35 patients. Before treatment, a clinical photograph and an incisional biopsy were

  19. Rapid prototyping of biodegradable microneedle arrays by integrating CO2 laser processing and polymer molding

    Science.gov (United States)

    Tu, K. T.; Chung, C. K.

    2016-06-01

    An integrated technology of CO2 laser processing and polymer molding has been demonstrated for the rapid prototyping of biodegradable poly-lactic-co-glycolic acid (PLGA) microneedle arrays. Rapid and low-cost CO2 laser processing was used for the fabrication of a high-aspect-ratio microneedle master mold instead of conventional time-consuming and expensive photolithography and etching processes. It is crucial to use flexible polydimethylsiloxane (PDMS) to detach PLGA. However, the direct CO2 laser-ablated PDMS could generate poor surfaces with bulges, scorches, re-solidification and shrinkage. Here, we have combined the polymethyl methacrylate (PMMA) ablation and two-step PDMS casting process to form a PDMS female microneedle mold to eliminate the problem of direct ablation. A self-assembled monolayer polyethylene glycol was coated to prevent stiction between the two PDMS layers during the peeling-off step in the PDMS-to-PDMS replication. Then the PLGA microneedle array was successfully released by bending the second-cast PDMS mold with flexibility and hydrophobic property. The depth of the polymer microneedles can range from hundreds of micrometers to millimeters. It is linked to the PMMA pattern profile and can be adjusted by CO2 laser power and scanning speed. The proposed integration process is maskless, simple and low-cost for rapid prototyping with a reusable mold.

  20. CO2 laser-inscribed low-cost, shortest-period long-period fibre ...

    Indian Academy of Sciences (India)

    2014-02-07

    Feb 7, 2014 ... LPG inscribed using CO2 laser in B–Ge-doped fibre as per our knowledge. Since boron doping increases the attenuation near 1500 nm, it is .... mission spectrum of TAP-LPG when it was fixed over two translation stages and strain was applied gradually by pulling one of the stages. Figure 4 shows the ...

  1. Application of Factorial Design for Gas Parameter Optimization in CO2 Laser Welding

    DEFF Research Database (Denmark)

    Gong, Hui; Dragsted, Birgitte; Olsen, Flemming Ove

    1997-01-01

    The effect of different gas process parameters involved in CO2 laser welding has been studied by applying two-set of three-level complete factorial designs. In this work 5 gas parameters, gas type, gas flow rate, gas blowing angle, gas nozzle diameter, gas blowing point-offset, are optimized...

  2. A DC excited waveguide multibeam CO2 laser using high frequency ...

    Indian Academy of Sciences (India)

    A DC excited waveguide multibeam CO2 laser is reported having six glass discharge tubes. Simultaneous excitation of DC discharge in all sections is achieved by producing pre-ionization using an auxiliary high frequency pulsed discharge along with its other advantages. Maximum 170 W output power is obtained with all ...

  3. Pulse forming in an AM mode-locking hybrid TEA-CO2 laser

    NARCIS (Netherlands)

    Bonnie, R.J.M.; van Goor, F.A.

    1986-01-01

    We performed an experimental study on the pulse forming mechanism in an AM mode-locked hybrid TEA-CO2 laser by means of “injection mode-locking”. The results show that bandwidth limited pulses will only be reached within a small - critical - range of parameters. Furthermore, under some stringent

  4. Gingival melanin pigmentation and its treatment with the CO2 laser.

    Science.gov (United States)

    Esen, Emin; Haytac, M Cenk; Oz, I Attila; Erdoğan, Ozgür; Karsli, Ebru D

    2004-11-01

    There are only a few reports in the literature evaluating the effects of the carbon dioxide (CO2) laser on gingival melanin pigmentation (GMP). This study was performed to evaluate the effects of the CO2 laser at superpulse mode, applied for gingival depigmentation. GMP at the anterior maxillary and mandibular gingiva of 10 patients was treated using the superpulsed CO2 laser (10 watts, 0.8 mm spot size, 20 Hz, 10 milliseconds). Pigmented areas were measured on pre- and postoperative standard digital images by the aid of an image- analyzing software. Statistical analysis of the data was performed by Mann Whitney U test. Ablation of the hyperpigmented gingiva was accomplished with minimal carbonization and almost no bleeding. Postoperative healing was uneventful with no significant postoperative pain. Two cases of partial repigmentation were observed during 24-month follow-up. Statistical analysis of the data revealed a significant difference between pre- and postoperative measurements of pigmented area. Application of the superpulse mode of CO2 laser appears to be an effective and safe method for the elimination of GMP.

  5. Efficacy of fractional CO2 laser in treatment of atrophic scar of cutaneous leishmaniasis.

    Science.gov (United States)

    Banihashemi, Mahnaz; Nahidi, Yalda; Maleki, Masoud; Esmaily, Habibollah; Moghimi, Hamid Reza

    2016-05-01

    Cutaneous leishmaniasis is an endemic disease in Iran. Unfortunately, it can lead to unsightly atrophic scars with limited treatment options. Fractional CO2 laser is accepted for treatment of atrophic acne scars and recently has been used to treat cutaneous leishmaniasis, so we planned to use fractional CO2 laser on leishmaniasis scar. We conducted this study on 60 leishmaniasis scars on the face of 40 patients. The lesions were treated by a fractional CO2 laser with beam size of 120 μm, with energy of 50-90 mJ, and 50-100 spots/cm(2) density with two passes in three monthly sessions. Evaluation was done in the first and second months after the first treatment and 3 and 6 months after the last treatment. Digital photography was performed at each visit. Assessment of improvement rate by patient and physician was rated separately as follows: no improvement (0%), mild (high efficacy of fractional CO2 laser for leishmaniasis scar. No significant adverse effects were noted.

  6. Study of plasma formation in CW CO2 laser beam-metal surface interaction

    Science.gov (United States)

    Azharonok, V. V.; Vasilchenko, Zh V.; Golubev, Vladimir S.; Gresev, A. N.; Zabelin, Alexandre M.; Chubrik, N. I.; Shimanovich, V. D.

    1994-04-01

    An interaction of the cw CO2 laser beam and a moving metal surface has been studied. The pulsed and thermodynamical parameters of the surface plasma were investigated by optical and spectroscopical methods. The subsonic radiation wave propagation in the erosion plasma torch has been studied.

  7. Laser Amplifier Development for the Remote Sensing of CO2 from Space

    Science.gov (United States)

    Yu, Anthony W.; Abshire, James B.; Storm, Mark; Betin, Alexander

    2015-01-01

    Accurate global measurements of tropospheric CO2 mixing ratios are needed to study CO2 emissions and CO2 exchange with the land and oceans. NASA Goddard Space Flight Center (GSFC) is developing a pulsed lidar approach for an integrated path differential absorption (IPDA) lidar to allow global measurements of atmospheric CO2 column densities from space. Our group has developed, and successfully flown, an airborne pulsed lidar instrument that uses two tunable pulsed laser transmitters allowing simultaneous measurement of a single CO2 absorption line in the 1570 nm band, absorption of an O2 line pair in the oxygen A-band (765 nm), range, and atmospheric backscatter profiles in the same path. Both lasers are pulsed at 10 kHz, and the two absorption line regions are sampled at typically a 300 Hz rate. A space-based version of this lidar must have a much larger lidar power-area product due to the approximately x40 longer range and faster along track velocity compared to airborne instrument. Initial link budget analysis indicated that for a 400 km orbit, a 1.5 m diameter telescope and a 10 second integration time, a approximately 2 mJ laser energy is required to attain the precision needed for each measurement. To meet this energy requirement, we have pursued parallel power scaling efforts to enable space-based lidar measurement of CO2 concentrations. These included a multiple aperture approach consists of multi-element large mode area fiber amplifiers and a single-aperture approach consists of a multi-pass Er:Yb:Phosphate glass based planar waveguide amplifier (PWA). In this paper we will present our laser amplifier design approaches and preliminary results.

  8. In-cell measurements of smoke backscattering coefficients using a CO2 laser system for application to lidar-dial forest fire detection

    Science.gov (United States)

    Bellecci, Carlo; Gaudio, Pasquale; Gelfusa, Michela; Lo Feudo, Teresa; Murari, Andrea; Richetta, Maria; de Leo, Leonerdo

    2010-12-01

    In the lidar-dial method, the amount of the water vapor present in the smoke of the vegetable fuel is detected to reduce the number of false alarms. We report the measurements of the smoke backscattering coefficients for the CO2 laser lines 10R20 and 10R18 as determined in an absorption cell for two different vegetable fuels (eucalyptus and conifer). These experimental backscattering coefficients enable us to determine the error to be associated to the water vapor measurements when the traditional first-order approximation is assumed. We find that this first-order approximation is valid for combustion rates as low as 100 g/s.

  9. 13CO2/12CO2 ratio analysis in exhaled air by lead-salt tunable diode lasers for noninvasive diagnostics in gastroenterology

    Science.gov (United States)

    Stepanov, Eugene V.; Zyrianov, Pavel V.; Miliaev, Valerii A.; Selivanov, Yurii G.; Chizhevskii, Eugene G.; Os'kina, Svetlana; Ivashkin, Vladimir T.; Nikitina, Elena I.

    1999-07-01

    An analyzer of 13CO2/12CO2 ratio in exhaled air based on lead-salt tunable diode lasers is presented. High accuracy of the carbon isotope ratio detection in exhaled carbon dioxide was achieved with help of very simple optical schematics. It was based on the use of MBE laser diodes operating in pulse mode and on recording the resonance CO2 absorption at 4.2 micrometers . Special fast acquisition electronics and software were applied for spectral data collection and processing. Developed laser system was tested in a clinical train aimed to assessment eradication efficiency in therapy of gastritis associated with Helicobacter pylori infection. Data on the 13C-urea breath test used for P.pylori detection and obtained with tunable diode lasers in the course of the trail was compared with the results of Mass-Spectroscopy analysis and histology observations. The analyzer can be used also for 13CO2/12CO2 ratio detection in exhalation to perform gastroenterology breath test based on using other compounds labeled with stable isotopes.

  10. CO2 laser nerve welding: optimal laser parameters and the use of solders in vitro.

    Science.gov (United States)

    Menovsky, T; Beek, J F; van Gemert, M J

    1994-01-01

    To improve the welding strength, an in vitro study was performed to investigate the bonding strength of CO2 laser nerve welding (LNW), with and without the use of human albumin solution, dried albumin solution, egg white, fibrinogen solution, fibrin glue, and red blood cells as a solder. Fifteen different combinations of laser power (50, 100, and 150 mW) and pulse duration (0.1 to 3 s) were used with a spot size of 320 microns. The results have been compared to suture, fibrin glue, and laser-assisted nerve repair (LANR). The strongest welds (associated with whitening and caramelization of tissue) were produced at 100 mW with pulses of 1.0 s and at 50 mW with pulses of 3 s. The use of a dried albumin solution as a solder at 100 mW with pulses of 1 s increased the bonding strength 9-fold as compared to LNW (bonding strength 21.0 +/- 8.6 g and 2.4 +/- 0.9 g, respectively). However, positioning the nerves between cottons soaked in saline for 20 minutes resulted in a decrease of the bonding strength (9.8 +/- 4.5 g). The use of a 20% albumin solution and egg white, both at 50 mW with pulses of 3 s, resulted in a bonding strength of, respectively, 5.7 +/- 2.1 g and 7.7 +/- 2.4 g. Other solders did not increase the bonding strength in comparison to LNW. The substantial increase in bonding strength for some solders suggests that it is worthwhile to investigate the dehiscence rate and nerve regeneration of solder enhanced LNW in an in vivo study.

  11. Fractional CO2 Laser Resurfacing as Monotherapy in the Treatment of Atrophic Facial Acne Scars.

    Science.gov (United States)

    Majid, Imran; Imran, Saher

    2014-04-01

    While laser resurfacing remains the most effective treatment option for atrophic acne scars, the high incidence of post-treatment adverse effects limits its use. Fractional laser photothermolysis attempts to overcome these limitations of laser resurfacing by creating microscopic zones of injury to the dermis with skip areas in between. The aim of the present study is to assess the efficacy and safety of fractional CO2 laser resurfacing in atrophic facial acne scars. Sixty patients with moderate to severe atrophic facial acne scars were treated with 3-4 sessions of fractional CO2 laser resurfacing at 6-week intervals. The therapeutic response to treatment was assessed at each follow up visit and then finally 6 months after the last laser session using a quartile grading scale. Response to treatment was labelled as 'excellent' if there was >50% improvement in scar appearance and texture of skin on the grading scale while 25-50% response and boxcar scars responded the best while pitted scars responded the least to fractional laser monotherapy. The commonest reported adverse effect was transient erythema and crusting lasting for an average of 3-4 and 4-6 days, respectively while three patients developed post-inflammatory pigmentation lasting for 8-12 weeks. Fractional laser resurfacing as monotherapy is effective in treating acne scars especially rolling and superficial boxcar scars with minimal adverse effects.

  12. High Repetition Rate Pulsed 2-Micron Laser Transmitter for Coherent CO2 DIAL Measurement

    Science.gov (United States)

    Singh, Uprendra N.; Bai, Yingxin; Yu, Jirong; Petros, Mulugeta; Petzar, Paul J.; Trieu, Bo C.; Lee, Hyung

    2009-01-01

    A high repetition rate, highly efficient, Q-switched 2-micron laser system as the transmitter of a coherent differential absorption lidar for CO2 measurement has been developed at NASA Langley Research Center. Such a laser transmitter is a master-slave laser system. The master laser operates in a single frequency, either on-line or off-line of a selected CO2 absorption line. The slave laser is a Q-switched ring-cavity Ho:YLF laser which is pumped by a Tm:fiber laser. The repetition rate can be adjusted from a few hundred Hz to 10 kHz. The injection seeding success rate is from 99.4% to 99.95%. For 1 kHz operation, the output pulse energy is 5.5mJ with the pulse length of approximately 50 ns. The optical-to-optical efficiency is 39% when the pump power is 14.5W. The measured standard deviation of the laser frequency jitter is about 3 MHz.

  13. Cutaneous pain effects induced by Nd:YAG and CO2 laser stimuli

    Science.gov (United States)

    Wang, Jia-Rui; Yu, Guang-Yuan; Yang, Zai-Fu; Chen, Hong-Xia; Hu, Dong-Dong; Zou, Xian-Biao

    2012-12-01

    The near infrared laser technique can activate cutaneous nociceptors with high specificity and reproducibility and be used in anti-riot equipment. This study aimed to explore cutaneous pain effect and determine the threshold induced by Nd:YAG and CO2 laser stimuli. The corresponding wavelength was 1.32μm and 10.6μm. The pain effect was assessed in three healthy subjects (1 woman and 2 men) on the skin of dorsum of both hands. The energy of each pulse and whether the subjects felt a painful sensation after each stimulus were recorded. A simplified Bliss Method was used to calculate the pain threshold which were determined under three pulse durations for Nd:YAG laser and one pulse duration for CO2 laser. As a result the pain thresholds were determined to be 5.6J/cm2, 5.4J/cm2 and 5.0J/cm2 respectively when using Nd:YAG laser, 4.0mm beam diameter, 8ms, 0.1s and 1s pulse duration. The pain threshold was 1.0J/cm2 when using CO2 laser, 4.0mm beam diameter and 0.1s pulse duration. We concluded that the threshold of cutaneous pain elicited by 1.32μm laser was independent upon the pulse duration when the exposure time ranged from 8ms to 1s. Under the same exposure condition, the threshold of cutaneous pain elicited by 1.32μm laser was higher than that elicited by 10.6μm laser.

  14. CO2 laser scribe of chemically strengthened glass with high surface compressive stress

    Science.gov (United States)

    Li, Xinghua; Vaddi, Butchi R.

    2011-03-01

    Chemically strengthened glass is finding increasing use in handheld, IT and TV cover glass applications. Chemically strengthened glass, particularly with high (>600MPa) compressive stress (CS) and deeper depth of layer (DOL), enable to retain higher strength after damage than non-strengthened glass when its surface is abraded. Corning Gorilla® Glass has particularly proven to be advantageous over competition in this attribute. However, due to high compressive stress (CS) and Central Tension (CT) cutting ion-exchanged glass is extremely difficult and often unmanageable where ever the applications require dicing the chemically strengthened mother glass into smaller parts. We at Corning have developed a CO2 laser scribe and break method (LSB) to separate a single chemically strengthened glass sheet into plurality of devices. Furthermore, CO2 laser scribe and break method enables debris-free separation of glass with high edge strength due to its mirror-like edge finish. We have investigated laser scribe and break of chemically strengthened glass with surface compressive stress greater than 600 MPa. In this paper we present the results of CO2 scribe and break method and underlying laser scribing mechanisms. We demonstrated cross-scribe repetitively on GEN 2 size chemically strengthened glass substrates. Specimens for edge strength measurements of different thickness and CS/DOL glass were prepared using the laser scribe and break technique. The specimens were tested using the standard 4-point bend method and the results are presented.

  15. CO2 laser surface treatment of failed dental implants for re-implantation: an animal study.

    Science.gov (United States)

    Kasraei, Shahin; Torkzaban, Parviz; Shams, Bahar; Hosseinipanah, Seyed Mohammad; Farhadian, Maryam

    2016-07-01

    The aim of the present study was to evaluate the success rate of failed implants re-implanted after surface treatment with CO2 laser. Despite the widespread use of dental implants, there are many incidents of failures. It is believed that lasers can be applied to decontaminate the implant surface without damaging the implant. Ten dental implants that had failed for various reasons other than fracture or surface abrasion were subjected to CO2 laser surface treatment and randomly placed in the maxillae of dogs. Three failed implants were also placed as the negative controls after irrigation with saline solution without laser surface treatment. The stability of the implants was evaluated by the use of the Periotest values (PTVs) on the first day after surgery and at 1, 3, and 6 months post-operatively. The mean PTVs of treated implants increased at the first month interval, indicating a decrease in implant stability due to inflammation followed by healing of the tissue. At 3 and 6 months, the mean PTVs decreased compared to the 1-month interval (P implant stability. The mean PTVs increased in the negative control group compared to baseline (P implants were significantly lower than control group at 3 and 6 months after implant placement (P implantation of failed implants in Jack Russell Terrier dogs after CO2 laser surface debridement is associated with a high success rate in terms of implant stability.

  16. Laser Coulomb Explosion Imaging of molecular dynamics in CO2 molecule

    Science.gov (United States)

    Legare, Francois; Bocharova, Irina; Litvinyuk, Igor; Sanderson, Joseph; Karimi, Reza

    2009-05-01

    Molecular structure dynamics and dissociation pathways of CO2 molecule initiated by interaction with strong laser field were investigated by Laser Coulomb Explosion Imaging (LCEI) technique. Momentum imaging of ions in tree-body fragmentation break-up channels O^++C^++O^+ (1,1,1) and O^2++C^2++O^2+ (2,2,2) was used to determine full geometry of CO2 ionic states before explosion. Varying laser pulse length from sub-7 fs to 200 fs at the same laser field intensity we were able to follow the evolution of the molecular structure and observe dramatic change in total kinetic energy of O^2++C^2++O^2+ channel with increasing pulse length. We observed significantly bent structure of parent ion and low kinetic energy of the (2,2,2) channel for long pulses, compared to the very close to linear geometry, and very high kinetic energy for sub-7 fs laser pulse. This observation supports the idea that a phenomenon known as enhanced ionization takes place for CO2 molecule with the same mechanism as in hydrogen molecule. It also lets us put temporal and spatial limits on this process, and in the future, probing molecular structure within the critical distance range, establish connection between changing geometry and dissociation pathways.

  17. Results of CO2 robotic laser oseotomy in surgery with motion compensation

    Science.gov (United States)

    Mönnich, Holger; Stein, Daniel; Raczkowsky, Jörg; Wörn, Heinz

    2010-02-01

    This paper presents a visual servoing application with and without motion compensation and a fixed visual servoing configuration for CO2 laser osteotomy. A multi camera system from ART is used to track the position of the robot and a skull via marker spheres that are attached to both. A CT scan from the skull is performed and segmented to acquire a 3D model. Inside the model the position for the robot for the laser ablation is planned. The accuracy of the lightweight robot is increased with the additional supervision of an optical tracking system. Accuracy improvement was measured with an FARO measurement arm. A visual servoing control schema is presented. The demonstrator shows a working visual servoing application for laser osteotomy. To improve the error resulting mainly from the delay to acquire the data from the devices a motion compensation algorithm is introduced based on iterative learning and a normalized Least Mean Square (nLMS) filter. The results during the simulation and the experimental setup are shown. The system was then evaluated with the CO2 laser system OsteoLas X10 from Caesar - Bonn, Germany. Different cuts are performed with the robot and the CO2 laser system. For the breathing motion a robotic breathing simulator is used. The reached accuracy and the cutting results on bone are shown.

  18. Preparation of γ-Al2O3 films by laser chemical vapor deposition

    Science.gov (United States)

    Gao, Ming; Ito, Akihiko; Goto, Takashi

    2015-06-01

    γ- and α-Al2O3 films were prepared by chemical vapor deposition using CO2, Nd:YAG, and InGaAs lasers to investigate the effects of varying the laser wavelength and deposition conditions on the phase composition and microstructure. The CO2 laser was found to mostly produce α-Al2O3 films, whereas the Nd:YAG and InGaAs lasers produced γ-Al2O3 films when used at a high total pressure. γ-Al2O3 films had a cauliflower-like structure, while the α-Al2O3 films had a dense and columnar structure. Of the three lasers, it was the Nd:YAG laser that interacted most with intermediate gas species. This promoted γ-Al2O3 nucleation in the gas phase at high total pressure, which explains the cauliflower-like structure of nanoparticles observed.

  19. A compact plasma pre-ionized TEA-CO2 laser pulse clipper for material processing

    Science.gov (United States)

    Gasmi, Taieb

    2017-08-01

    An extra-laser cavity CO2-TEA laser pulse clipper using gas breakdown techniques for high spatial resolution material processing and shallow material engraving and drilling processes is presented. Complete extinction of the nitrogen tail, that extends the pulse width, is obtained at pressures from 375 up to 1500 torr for nitrogen and argon gases. Excellent energy stability and pulse repeatability were further enhanced using high voltage assisted preionized plasma gas technique. Experimental data illustrates the direct correlation between laser pulse width and depth of engraving in aluminum and alumina materials.

  20. Energy modulation of nonrelativistic electrons with a CO2 laser using a metal microslit

    OpenAIRE

    Jongsuck, Bae; Ryo, Ishikawa; Sumio, Okuyama; Takashi, Miyajima; Taiji, Akizuki; Tatsuya, Okamoto; Koji, Mizuno

    2000-01-01

    A metal microslit has been used as an interaction circuit between a CO2 laser beam and nonrelativistic free electrons. Evanescent waves which are induced on the slit by illumination of the laser light modulate the energy of electrons passing close to the surface of the slit. The electron-energy change of more than ±5 eV for the 80 keV electron beam has been observed using the 7 kW laser beam at the wavelength of 10.6 μm.

  1. Energy modulation of nonrelativistic electrons with a CO2 laser using a metal microslit

    Science.gov (United States)

    Bae, Jongsuck; Ishikawa, Ryo; Okuyama, Sumio; Miyajima, Takashi; Akizuki, Taiji; Okamoto, Tatsuya; Mizuno, Koji

    2000-04-01

    A metal microslit has been used as an interaction circuit between a CO2 laser beam and nonrelativistic free electrons. Evanescent waves which are induced on the slit by illumination of the laser light modulate the energy of electrons passing close to the surface of the slit. The electron-energy change of more than ±5 eV for the 80 keV electron beam has been observed using the 7 kW laser beam at the wavelength of 10.6 μm.

  2. Effect of a target on the stimulated emission of microsecond CO2-laser pulses

    Science.gov (United States)

    Baranov, V. Iu.; Dolgov, V. A.; Maliuta, D. D.; Mezhevov, V. S.; Semak, V. V.

    1987-12-01

    The paper reports a change in the pulse shape of a TEA CO2 laser with an unstable cavity under the interaction between the laser radiation and a metal surface in the presence of a breakdown plasma. It is shown that a continuous change in the phase difference between the wave reflected in the cavity and the principal cavity wave gives rise to changes in the pulse shape and the appearance of power fluctuations. The possible effect of these phenomena on the laser treatment of materials is considered.

  3. Enhancing growth of cultured human skin cells using low-energy CO2 laser

    Science.gov (United States)

    Grossman, Nili; Reuveni, Haim; Halevy, Sima; Lubart, Rachel

    1997-12-01

    In view of the versatility and usage of the CO2 laser as a too. in surgery and dermatology, we have studied its effect on enhancing proliferation of cultured skin cells using an attenuated CO2 laser. Exposure of cultured keratinocytes or fibroblasts to continuous wave or pulse mode irradiation enhanced thymidine incorporation by 1.4 to 1.7 folds, and cell number by 1.25 to 1.4 folds, measured 24 and 48 hours later, depending on the fluency applied. As expected, these effects were not suppressed by added antioxidants, indicating that the mechanism involved in this newly observed effect, differ from photosensitization by low energy visible and near IR lasers.

  4. Management of recalcitrant oral pemphigus vulgaris with CO 2 laser - Report of two cases

    Directory of Open Access Journals (Sweden)

    Bhardwaj Ashu

    2010-01-01

    Full Text Available Laser has been used efficiently for treatment of oral lichen planus, leukoplakia, aphthous ulcers and oral manifestations of HIV. Two cases of recalcitrant oral pemphigus vulgaris that were successfully treated with CO 2 laser are described. The patients had been treated by a dermatologist with pulse therapy of methyl prednisolone and cyclophosphamide over a period of 6 to 8 months, but the clinical course was characterized by episodes of painful flare-ups and nonresponsiveness. The patients were extremely uncomfortable with recurrent oral lesions. CO 2 laser at low power was used to irradiate the lesions. It was shown to be effective in relieving pain and healing of lesions, with nonrecurrence. To the best of our knowledge, this is the first case report of such a treatment of oral pemphigus vulgaris. Further clinical studies are warranted to confirm efficacy and to optimize the treatment protocol.

  5. Development of Laser, Detector, and Receiver Systems for an Atmospheric CO2 Lidar Profiling System

    Science.gov (United States)

    Ismail, Syed; Koch, Grady; Abedin, Nurul; Refaat, Tamer; Rubio, Manuel; Singh, Upendra

    2008-01-01

    A ground-based Differential Absorption Lidar (DIAL) is being developed with the capability to measure range-resolved and column amounts of atmospheric CO2. This system is also capable of providing high-resolution aerosol profiles and cloud distributions. It is being developed as part of the NASA Earth Science Technology Office s Instrument Incubator Program. This three year program involves the design, development, evaluation, and fielding of a ground-based CO2 profiling system. At the end of a three-year development this instrument is expected to be capable of making measurements in the lower troposphere and boundary layer where the sources and sinks of CO2 are located. It will be a valuable tool in the validation of NASA Orbiting Carbon Observatory (OCO) measurements of column CO2 and suitable for deployment in the North American Carbon Program (NACP) regional intensive field campaigns. The system can also be used as a test-bed for the evaluation of lidar technologies for space-application. This DIAL system leverages 2-micron laser technology developed under a number of NASA programs to develop new solid-state laser technology that provides high pulse energy, tunable, wavelength-stabilized, and double-pulsed lasers that are operable over pre-selected temperature insensitive strong CO2 absorption lines suitable for profiling of lower tropospheric CO2. It also incorporates new high quantum efficiency, high gain, and relatively low noise phototransistors, and a new receiver/signal processor system to achieve high precision DIAL measurements.

  6. Advantages of CO2 laser use in surgical management of otosclerosis

    Directory of Open Access Journals (Sweden)

    Matković Svjetlana

    2003-01-01

    Full Text Available Background. Otosclerosis is a progressive osteo-destructive disorder of the bony labyrinth in which the fixation of the stapes causes the hearing loss. The aim of this study was the postoperative determination of parameters of the effect of surgical intervention on hearing and the incidence of complications and, on the basis of the differences in the examined parameters of the study, the estimation of the eficacy of the two mentioned surgical thechniques in the treatment of otosclerosis. Methods. In our research 40 patients with conductive hearing loss caused by otosclerosis underwent surgery with CO2 laser. Functional results were compared postoperatively with the results of 40 patients operated by the classical technique without the use of CO2 laser. The research was accomplished as a prospective comparative study. Results. The air-bone interval (gap as the difference between the rim of air and bone conductivity for separate frequencies did not significantly differ between the control and the experimental group. Both methods were effective in closing the air-bone gap with the rates of closure to within 10 dB in 82.6% and 75.3% for the laser and drill, respectively. The incidence of tinnitus was significantly lower in patients who underwent surgery with CO2 laser. The frequency of intraoperative and postoperative complications was significantly lower in the laser group. Differences were statistically significant for all parameters (p<0.05. Conclusion. On the basis of the degree of postoperative hearing improvement, tinnitus and the incidence of complications it can be concluded that the use of CO2 laser during inverse stapedoplasty represents an effective and safe method, justifying the promotion of its use in the surgical management of otosclerosis.

  7. Experimental Investigation of Axial and Beam-Riding Propulsive Physics with TEA CO2 laser

    Science.gov (United States)

    Kenoyer, D. A.; Salvador, I.; Myrabo, L. N.; Notaro, S. N.; Bragulla, P. W.

    2010-10-01

    A twin Lumonics K922M pulsed TEA CO2 laser system (pulse duration of approximately 100 ns FWHM spike, with optional 1 μs tail, depending upon laser gas mix) was employed to experimentally measure both axial thrust and beam-riding behavior of Type ♯200 lightcraft engines, using a ballistic pendulum and Angular Impulse Measurement Device (AIMD, respectively. Beam-riding forces and moments were examined along with engine thrust-vectoring behavior, as a function of: a) laser beam lateral offset from the vehicle axis of symmetry; b) laser pulse energy (˜12 to 40 joules); c) pulse duration (100 ns, and 1 μs); and d) engine size (97.7 mm to 161.2 mm). Maximum lateral momentum coupling coefficients (CM) of 75 N-s/MJ were achieved with the K922M laser whereas previous PLVTS laser (420 J, 18 μs duration) results reached only 15 N-s/MJ—an improvement of 5x. Maximum axial CM performance with the K922M reached 225 N-s/MJ, or about ˜3x larger than the lateral CM values. These axial CM results are sharply higher than the 120 N/MW previously reported for long pulse (e.g., 10-18 μs) CO2 electric discharge lasers.

  8. Thick Er-doped silica films sintered using CO2 laser for scintillation applications

    Science.gov (United States)

    Lei, Jincheng; Trofimov, Artem A.; Chen, Jie; Chen, Zhaoxi; Hong, Yuzhe; Yuan, Lei; Zhu, Wenge; Zhang, Qi; Jacobsohn, Luiz G.; Peng, Fei; Bordia, Rajendra K.; Xiao, Hai

    2017-06-01

    In this work, we demonstrated the fabrication of crack-free luminescent Er-doped silica coatings sintered using a CO2 laser. The silica sol-gel precursor with controllable rheology was developed using tetraethyl orthosilicate (TEOS) and hexamethyldisiloxane (HMDS). Luminescence activation was achieved through doping with Er ions. Coatings sintered at 1100 °C presented green photoluminescence at ∼550 nm and strong radioluminescence as well. After dip-coating, crack-free Er-doped silica thin films were obtained using a CO2 laser. Films sintered by laser had similar microstructure as the films sintered in a furnace. However, laser sintering extended the thickness range for making crack free sintered films. Using laser sintering, the thickness of crack-free silica films could be extended to above 1 μm, which is important for scintillation and optical waveguide applications. In order to understand the cracking control mechanism, a finite element (FEM) model was developed to analyze the stress distribution within the laser-sintered thin film. The model showed that the localized nature of sintering by laser heating allows for constrained sintering stress relaxation by the softer surrounding region of the film, effectively suppressing cracking.

  9. Direct acceleration of electrons by a CO2 laser in a curved plasma waveguide

    Science.gov (United States)

    Yi, Longqing; Pukhov, Alexander; Shen, Baifei

    2016-06-01

    Laser plasma interaction with micro-engineered targets at relativistic intensities has been greatly promoted by recent progress in the high contrast lasers and the manufacture of advanced micro- and nano-structures. This opens new possibilities for the physics of laser-matter interaction. Here we propose a novel approach that leverages the advantages of high-pressure CO2 laser, laser-waveguide interaction, as well as micro-engineered plasma structure to accelerate electrons to peak energy greater than 1 GeV with narrow slice energy spread (~1%) and high overall efficiency. The acceleration gradient is 26 GV/m for a 1.3 TW CO2 laser system. The micro-bunching of a long electron beam leads to the generation of a chain of ultrashort electron bunches with the duration roughly equal to half-laser-cycle. These results open a way for developing a compact and economic electron source for diverse applications.

  10. High-speed high-efficiency 500-W cw CO2 laser hermetization of metal frames of microelectronics devices

    Science.gov (United States)

    Levin, Andrey V.

    1996-04-01

    High-speed, efficient method of laser surface treatment has been developed using (500 W) cw CO2 laser. The principal advantages of CO2 laser surface treatment in comparison with solid state lasers are the basis of the method. It has been affirmed that high efficiency of welding was a consequence of the fundamental properties of metal-IR-radiation (10,6 mkm) interaction. CO2 laser hermetization of metal frames of microelectronic devices is described as an example of the proposed method application.

  11. Simple, compact, and low cost CO2 laser driven by fast high voltage solid state switch for industrial application

    Science.gov (United States)

    Tanaka, Miyu; Tei, Masaya; Uno, Kazuyuki; Nakano, Hitoshi

    2017-02-01

    A longitudinally excited CO2 laser driven with a reverse recovery characteristics of high voltage diode has been developed. A diode is used to control the high voltage pulse as an opening switch. Power supply for longitudinally excited CO2 laser is composed of a pulse generator, transformer, capacitor, and a diode, is very simple. Laser oscillation has been successfully achieved, several tens of mJ in laser energy has been obtained.

  12. Energy balance in high-quality cutting of steel by fiber and CO2 lasers

    Science.gov (United States)

    Fomin, V. M.; Golyshev, A. A.; Orishich, A. M.; Shulyat'ev, V. B.

    2017-03-01

    The energy balance of laser cutting of low-carbon and stainless steel sheets with the minimum roughness of the cut surface is experimentally studied. Experimental data obtained in wide ranges of cutting parameters are generalized with the use of dimensionless parameters (Peclet number and absorbed laser energy). It is discovered for the first time that the minimum roughness is ensured at a certain value of energy per unit volume of the melt (approximately 26 J/mm3), regardless of the gas type (oxygen or nitrogen) and laser type (fiber laser with a wavelength of 1.07 μm or CO2 laser with a wavelength of 10.6 μm).

  13. Influence of secondary treatment with CO2 laser irradiation for mitigation site on fused silica surface

    Science.gov (United States)

    Jiang, Yong; Zhou, Qiang; Qiu, Rong; Gao, Xiang; Wang, Hui-Li; Yao, Cai-Zhen; Wang, Jun-Bo; Zhao, Xin; Liu, Chun-Ming; Xiang, Xia; Zu, Xiao-Tao; Yuan, Xiao-Dong; Miao, Xin-Xiang

    2016-10-01

    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 CO2 laser 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 CO2 laser secondary treatment. Project supported by the National Natural Science Foundation of China (Grant Nos. 61505170, 61505171, and 51535003), the Joint Fund of the National Natural Science Foundation of China, the Chinese Academy of Engineering Physics (Grant No. U1530109), and the China Postdoctoral Science Foundation (Grant No. 2016M592709).

  14. CO2 Laser-Mediated Apically Positioned Flap in Areas Lacking Keratinized Gingiva.

    Science.gov (United States)

    Zeinoun, Toni; Majzoub, Zeina; Khoury, Carlos; Nammour, Samir

    2017-06-30

    Autogenous gingival grafts are considered the "gold standard" for gingival augmentation, however they require a second surgical site for graft harvesting. Apically positioned flaps (APFs) represent an alternative method in soft tissue augmentation procedures. Limited information is available relative to the effectiveness of laser-mediated APF in augmenting keratinized gingiva (KG). The aim of this paper is to evaluate soft tissues changes following APF using CO2 laser in mandibular incisors with minimal KG and high labial frenum attachment. A total of 20 patients with minimal amount of KG (APF consisting of a single superficial horizontal incision just coronal to the mucogingival junction using CO2 laser, elevation of a split-thickness flap, and suturing of the flap to the periosteum in an apical position was performed. The apico-coronal height of KG was measured at baseline, and at 3, 6 and 12 months postoperatively. Uneventful healing was observed in all patients and an increase in KG of 2-3 mm was obtained. Most patients rated the procedure and the postoperative course as non painful. CO2 laser-assisted APF procedure is a minimally invasive treatment modality associated with reduced risk of bleeding and predictable increase in the height of KG.

  15. Benefits of CO2 laser heating for high reliability fiber splicing

    Science.gov (United States)

    Duke, Douglas M.; Nasir, Usman; Saravanos, Elli

    2016-03-01

    The use of a CO2 laser as a heat source became commercially available for optical fiber splicing and component fabrication only in recent years. In addition to long-term trouble-free and low-maintenance heat source operation, laser fusion splicing offers unique benefits for fabricating high-power optical components, as well as for splice reliability. When used as the heating method for fiber splicing, the energy of the CO2 laser beam is efficiently absorbed by the outer layer of the glass, and is then conducted inwards. This heating method is well controlled, and results in a smooth and contamination-free glass surface. Other heating methods, such as arc fusion or resistive heating, may leave tungsten, graphite, or metal oxide deposits on the spliced fiber surface. By contrast, with CO2 laser splicing, the lack of surface irregularities and contamination enables remarkable spliced-fiber strength results, with some strength results nearly within the range of coated fiber breaking strength.

  16. Microsecond enamel ablation with 10.6μm CO2 laser radiation

    Science.gov (United States)

    Góra, W. S.; McDonald, A.; Hand, D. P.; Shephard, J. D.

    2016-02-01

    Lasers have been previously been used for dental applications, however there remain issues with thermally-induced cracking. In this paper we investigate the impact of pulse length on CO2 laser ablation of human dental enamel. Experiments were carried in vitro on molar teeth without any modification to the enamel surface, such as grinding or polishing. In addition to varying the pulse length, we also varied pulse energy and focal position, to determine the most efficient ablation of dental hard tissue and more importantly to minimize or eradicate cracking. The maximum temperature rise during the multi pulse ablation process was monitored using a set of thermocouples embedded into the pulpal chamber. The application of a laser device in dental surgery allows removal of tissue with higher precision, which results in minimal loss of healthy dental tissue. In this study we use an RF discharge excited CO2 laser operating at 10.6μm. The wavelength of 10.6 μm overlaps with a phosphate band (PO3-4) absorption in dental hard tissue hence the CO2 laser radiation has been selected as a potential source for modification of the tissue. This research describes an in-depth analysis of single pulse laser ablation. To determine the parameters that are best suited for the ablation of hard dental tissue without thermal cracking, a range of pulse lengths (10-200 μs), and fluences (0-100 J/cm2) are tested. In addition, different laser focusing approaches are investigated to select the most beneficial way of delivering laser radiation to the surface (divergent/convergent beam). To ensure that these processes do not increase the temperature above the critical threshold and cause the necrosis of the tissue a set of thermocouples was placed into the pulpal chambers. Intermittent laser radiation was investigated with and without application of a water spray to cool down the ablation site and the adjacent area. Results show that the temperature can be kept below the critical threshold

  17. Increased reliability of passive mode-locking a multi-atmosphere TE CO2 laser by injection mode-locking

    NARCIS (Netherlands)

    van Goor, F.A.

    1986-01-01

    By injection of manosecond pulses from an AM mode-locked TEA CO2 laser in a passive mode-locked multi-atmosphere TE CO2 laser the shot-to-shot reproducibility of the generated subnanosecond pulses was increased to almost 100%.

  18. Hypertrophic scars after therapy with CO2 laser for treatment of multiple cutaneous neurofibromas

    NARCIS (Netherlands)

    J.U. Ostertag (Judith); C.C.W. Theunissen (Chantal); H.A.M. Neumann (Martino)

    2002-01-01

    textabstractBACKGROUND. CO2 laser surgery is a treatment modality for cutaneous neurofibromas. OBJECTIVE. Hypertrophic and atrophic scars can result from treatment with CO2 laser surgery. We present a case of cutaneous neurofibromatosis that developed hypertrophic scars postoperatively. METHODS.

  19. Diffusion of Co and W in diamond tool induced by 10.6 µm CO2 laser radiation

    CSIR Research Space (South Africa)

    Masina, Bathusile N

    2011-05-01

    Full Text Available www.csir.co.za Experimental setup CO2 laser ZnSe lens, f = 250 mm HPHT diamond sample Infrared camera Slide 8 © CSIR 2009 www.csir.co.za Experimental setup CO2 laser ZnSe lens, f = 250 mm HPHT diamond sample Infrared camera...

  20. Dentin bond strength after ablation using a CO2 laser operating at high pulse repetition rates

    Science.gov (United States)

    Hedayatollahnajafi, Saba; Staninec, Michal; Watanabe, Larry; Lee, Chulsung; Fried, Daniel

    2009-02-01

    Pulsed CO2 lasers show great promise for the rapid and efficient ablation of dental hard tissues. Our objective was to demonstrate that CO2 lasers operated at high repetition rates can be used for the rapid removal of dentin without excessive thermal damage and without compromising adhesion to restorative materials. Human dentin samples (3x3mm2) were rapidly ablated with a pulsed CO2 laser operating at a wavelength of 9.3-µm, pulse repetition rate of 300-Hz and an irradiation intensity of 18-J/cm2. The bond strength to composite was determined by the modified single plane shear test. There were 8 test groups each containing 10 blocks: negative control (non-irradiated non-etched), positive control (non-irradiated acid-etched), and six laser treated groups (three etched and three non-etched sets). The first and second etched and non-etched sets were ablated at a speed of 25 mm/sec and 50 mm/sec with water, respectively. The third set was also ablated at 50 mm/sec without application of water during laser irradiation. Minimal thermal damage was observed on the dentin surfaces for which water cooling was applied. Bond strengths exceeded 20 MPa for laser treated surfaces that were acid-etched after ablation (25-mm/sec: 29.9-MPa, 50-mm/sec: 21.3-MPa). The water-cooled etched laser groups all produced significantly stronger bonds than the negative control (pbond strength than the positive control (pbond strength than the acid-etched control samples is clinically significant where durability of these bonded restoration supersedes high bond strength.

  1. Caries inhibition in vital teeth using 9.6-μm CO2-laser irradiation

    Science.gov (United States)

    Rechmann, Peter; Fried, Daniel; Le, Charles Q.; Nelson, Gerald; Rapozo-Hilo, Marcia; Rechmann, Beate M. T.; Featherstone, John D. B.

    2011-07-01

    The aim of this study was to test the hypothesis that in a short-term clinical pilot trial short-pulsed 9.6 μm CO2-laser irradiation significantly inhibits demineralization in vivo. Twenty-four subjects scheduled for extraction of bicuspids for orthodontic reasons (age 14.9 +/- 2.2 years) were recruited. Orthodontic brackets were placed on bicuspids (Transbond XT, 3M). An area next to the bracket was irradiated with a CO2-laser (Pulse System Inc, Los Alamos, New Mexico), wavelength 9.6 μm, pulse duration 20 μs, pulse repetition rate 20 Hz, beam diameter 1100 μm, average fluence 4.1 +/- 0.3J/cm2, 20 laser pulses per spot. An adjacent nonirradiated area served as control. Bicuspids were extracted after four and twelve weeks, respectively, for a quantitative assessment of demineralization by cross-sectional microhardness testing. For the 4-week arm the mean relative mineral loss ΔZ (vol% × μm) for the laser treated enamel was 402 +/- 85 (mean +/- SE), while the control showed significantly higher mineral loss (ΔZ 738 +/- 131; P = 0.04, t-test). The difference was even larger after twelve weeks (laser arm ΔZ 135 +/- 98; control 1067 +/- 254; P = 0.002). The laser treatment produced 46% demineralization inhibition for the 4-week and a marked 87% inhibition for the 12-week arm. This study shows, for the first time in vivo, that the short-pulsed 9.6 μm CO2-laser irradiation successfully inhibits demineralization of tooth enamel in humans.

  2. Range Resolved CO2 Atmospheric Backscattering Measurements Using Fiber Lasers and RZPN Code Modulation

    Science.gov (United States)

    Burris, John

    2011-01-01

    We report the use of a return-to- zero (RZPN) pseudo noise modulation technique for making range resolved measurements of CO2 within the planetary boundary layer (PBL) using commercial, off-the-shelf, components. Conventional, range resolved, DIAL measurements require laser pulse widths that are significantly shorter than the desired spatial resolution and necessitate using pulses whose temporal spacing is such that scattered returns from only a single pulse are observed by the receiver at any one time (for the PBL pulse separations must be greater than approximately 20 microseconds). This imposes significant operational limitations when using currently available fiber lasers because of the resulting low duty cycle (less than approximately 0.0005) and consequent low average laser output power. The RZPN modulation technique enables a fiber laser to operate at much higher duty cycles (approaching 0.04) thereby more effectively utilizing the amplifier's output. This increases the counts received by approximately two orders of magnitude. Our approach involves employing two distributed feedback lasers (DFB), each modulated by a different RPZN code, whose outputs are then amplified by a CW fiber amplifier. One laser is tuned to a CO2 absorption line; the other operates offline thereby permitting the simultaneous acquisition of both on and offline signals using independent RZPN codes. This minimizes the impact of atmospheric turbulence on the measurement. The on and offline signals are retrieved by deconvolving the return signal using the appropriate kernels.

  3. CO2 Laser (10.6 microm) parameters for caries prevention in dental enamel.

    Science.gov (United States)

    Esteves-Oliveira, M; Zezell, D M; Meister, J; Franzen, R; Stanzel, S; Lampert, F; Eduardo, C P; Apel, C

    2009-01-01

    Although CO(2) laser irradiation can decrease enamel demineralisation, it has still not been clarified which laser wavelength and which irradiation conditions represent the optimum parameters for application as preventive treatment. The aim of the present explorative study was to find low-fluence CO(2) laser (lambda = 10.6 microm) parameters resulting in a maximum caries-preventive effect with the least thermal damage. Different laser parameters were systematically evaluated in 3 steps. In the first experiment, 5 fluences of 0.1, 0.3, 0.4, 0.5 and 0.6 J/cm(2), combined with high repetition rates and 10 micros pulse duration, were chosen for the experiments. In a second experiment, the influence of different pulse durations (5, 10, 20, 30 and 50 micros) on the demineralisation of dental enamel was assessed. Finally, 3 different irradiation times (2, 5 and 9 s) were tested in a third experiment. In total, 276 bovine enamel blocks were used for the experiments. An 8-day pH-cycling regime was performed after the laser treatment. Demineralisation was assessed by lesion depth measurements with a polarised light microscope, and morphological changes were assessed with a scanning electron microscope. Irradiation with 0.3 J/cm(2), 5 micros, 226 Hz for 9 s (2,036 overlapping pulses) increased caries resistance by up to 81% compared to the control and was even significantly better than fluoride application (25%, p laser irradiation. (c) 2009 S. Karger AG, Basel.

  4. CO2 Laser Microchanneling Process: Effects of Compound Parameters and Pulse Overlapping

    Science.gov (United States)

    Prakash, Shashi; Kumar, Subrata

    2016-09-01

    PMMA (Polymethyl methacrylate) is commonly used in many microfluidic devices like Lab-on-a-chip devices, bioanalytical devices etc. CO2 lasers provide easy and cost effective solution for micromachining needs on PMMA. Microchannels are an integral part of most of these microfluidic devices. CO2 laser beams have been successfully applied by many authors to fabricate microchannels on PMMA substrates. Laser beam power and scanning speed are the most important laser input parameters affecting the output parameters like microchannel depth, width and heat affected zone (HAZ). The effect of these individual parameters on output parameters are well known and already elaborated by many authors. However, these output parameters can more significantly be described by some compound parameters (combination of direct input laser parameters) like laser fluence, specific point energy, interaction time and P/U (power/scanning speed) ratio. The explanation of effect of these compound parameters was not found in earlier researches. In this work, several experiments were carried out to determine the effects of these compound parameters on output parameters i.e. microchannel width, depth and heat affected zone. The effect of pulse overlapping was also determined by performing experiments at different pulse overlaps and with two different energy deposition settings. The concept of actual pulse overlapping has been introduced by considering actual beam spot diameter instead of using theoretical beam diameter. Minimum pulse overlapping was determined experimentally in order to ensure smooth microchannel edges.

  5. Treatment of laryngeotracheal papillomatosis with the CO2 and Nd:YAG laser

    Science.gov (United States)

    Sedlmaier, Benedikt W.; Jovanovic, Sergije

    2000-06-01

    Papillomas are the most common benign neoplasms of the larynx and trachea. There are two types with different biological behavior, both caused by the human papilloma virus: the form that usually manifest itself in adults as a solitary, rarely recurring lesion, whereas one form that manifests in children and adults. It involves multiple lesions with a tendency to spread and recur. There is still no alternative to repeated surgical removal of the papillomas. In a retrospective study the results of laser surgery are compared with the results of instrumental removal of papillomas. The larynges were treated with the CO2 laser applied via high-precision micromanipulators combined with different scanner systems. In cases where the disease has spread into the cervical trachea, the papilloma foci were exposed by special subglottoscopes prior to transglottic removal with the CO2 laser via the operating microscope. The Nd:YAG laser applied through a jet ventilation tracheoscope via optical fibers has proven useful for involvement of the intrathoracic trachea. The use of the laser has not reduce the recurrency rate but the rate of late complications such as anterior synechia. Furthermore in extensive disease laser therapy enables a controlled bloodless removal even in the thoracic trachea and bronchi.

  6. An audit of the use of the CO2 laser in oral and maxillofacial surgery

    Science.gov (United States)

    Pinheiro, Antonio L. B.; Santos de Almeida, Darcy

    2004-09-01

    The use of the Carbon dioxide Laser to perform surgical procedures in the oral cavity has been described as a successful method for the treatment of several conditions affecting the maxillofacial region. Several benefits of the use of the CO2 Laser have been reported and includes reduction of postoperative pain and edema, local hemosthasis, reduction of scaring and wound contraction and infection. The aim of this work is to present our clinical experience in performing several surgical procedures using the CO2 Laser to treat soft tissue pathologies of both benign and malign origin as well as on performing pre-prosthetic surgery, apical surgery and on the treatment of pre-malignancies. Our experience demonstrate that the use of the Carbon dioxide Laser in treating oral soft-tissue pathology presents advantages over conventional techniques and local discomfort and pain are the most common complaints after Laser surgery. The Carbon dioxide Laser does not offer any enhanced cure-rate for oral pathology, but rather it is a precise means of removing soft tissue lesions with little upset afterwards.

  7. An attemp to use a pulsed CO2 laser for decontamination of radioactive metal surfaces

    Directory of Open Access Journals (Sweden)

    MILAN S. TRTICA

    2000-06-01

    Full Text Available There is a growing interest in laser radioactive decontamination of metal surfaces. It offers advantages over conventional methods: improved safety, reduction of secondary waste, reduced waste volume, acceptable cost. The main mechanism of cleaning by lasers is ablation. A pulsed TEA CO2 laser was used in this work for surface cleaning in order to show that ablation of metal surfaces is possible even at relatively low pulse energies, and to suggest that it could be competitive with other lasers because of much higher energy efficiencies. A brief theoretical analysis was made before the experiments. The laser beam was focused using a KBr-lens onto a surface contaminated with 137Cs (b-, t1/2 = 30.17 y. Three different metals were used: stainless steel, copper and aluminium. The ablated material was pumped out in an air atmosphere and transferred to a filter. The presence of activity on the filter was shown by a germanium detector-multichannel analyzer. The activity levels were measured by a GM counter. The calculated decontamination factors and collection factors showed that ablation occurs with a relatively high efficiency of decontamination. This investigation suggests that decontamination using a CO2 laser should be seriously considered.

  8. Ablative fractional laser treatment for hypertrophic scars: comparison between Er:YAG and CO2 fractional lasers.

    Science.gov (United States)

    Choi, Jae Eun; Oh, Ga Na; Kim, Jong Yeob; Seo, Soo Hong; Ahn, Hyo Hyun; Kye, Young Chul

    2014-08-01

    Nonablative fractional photothermolysis has been reported to show early promise in the treatment of hypertrophic scars, but there are few reports on ablative fractional photothermolysis for the treatment of hypertrophic scars. To evaluate and compare the efficacy and safety of Er:YAG fractional laser (EYFL) and CO2 fractional laser (CO2FL) for treatment of hypertrophic scars. Thirteen patients with hypertrophic scars were treated with 2,940 nm EYFL, and ten were treated with 10,600 nm CO2FL. An independent physician evaluator assessed the treatment outcomes using Vancouver scar scale (VSS) and 5-point grading scale (grade 0, no improvement; grade 1, 1-25%; grade 2, 26-50%; grade 3, 51-75%; grade 4, 76-100% improvement). Patients are queried about their subjective satisfaction with the treatment outcomes. After the final treatment, average percentage changes of VSS were 28.2% for EYFL and 49.8% for CO2FL. Improvement was evident in terms of pliability, while insignificant in terms of vascularity and pigmentation. Based on physician's global assessment, mean grade of 1.8 for EYFL and 2.7 for CO2FL was achieved. Patient's subjective satisfaction scores paralleled the physician's objective evaluation. CO2FL is a potentially effective and safe modality for the treatment of hypertrophic scars, particularly in terms of pliability.

  9. Volcanic CO2 mapping and flux measurements at Campi Flegrei by Tunable Diode Laser absorption Spectroscopy

    Science.gov (United States)

    Pedone, Maria; Aiuppa, Alessandro; Giudice, Gaetano; Grassa, Fausto; Chiodini, Giovanni; Valenza, Mariano

    2014-05-01

    Near-infrared room-temperature Tunable Diode Lasers (TDL) have recently found increased usage in atmospheric chemistry and air monitoring research, but applications in Volcanology are still limited to a few examples. Here, we explored the potentiality of a commercial infrared laser unit (GasFinder 2.0 from Boreal Laser Ltd) to measurement of volcanic CO2 flux emissions. Our field tests were conducted at Campi Flegrei (near Pozzuoli, Southern Italy), where the GasFinder was used (during three campaigns in October 2012, January 2013 and May 2013) to repeatedly measure the path-integrated concentrations of CO2 along cross-sections of the atmospheric plumes of the two main fumarolic fields in the area (Solfatara and Pisciarelli). By using ad-hoc designed field-set-up and a tomographic post-processing routine, we resolved, for each of the 2 manifestations, the contour maps of CO2 concentrations in their atmospheric plumes, from the integration of which (and after multiplication by the plumes' transport speeds) the CO2 fluxes were finally obtained [1]. The so-calculated fluxes average of 490 tons/day, which agrees well with independent evaluations of Aiuppa et al. (2013) [2] (460 tons/day on average), and support a significant contribution of fumaroles to the total CO2 budget. The cumulative (fumarole [this study] +soil [2]) CO2 output from Campi Flegrei is finally evaluated at 1600 tons/day. The application of lasers to volcanic gas studies is still an emerging (though intriguing) research field, and requires more testing and validation experiments. We conclude that TDL technique may valuably assist CO2 flux quantification at a number of volcanic targets worldwide. [1] Pedone M. et al. (2013) Gold2013:abs:5563, Goldschmidt Conference, session 11a. [2] Aiuppa A. et al. (2013) Geochemistry Geophysics Geosystems. doi: 10.1002/ggge.20261. [3] Chiodini G. et al. (2010) Journal of Geophysical Research, Volume 115, B03205. doi:10.1029/2008JB006258.

  10. Fractional CO 2 laser resurfacing as monotherapy in the treatment of atrophic facial acne scars

    Directory of Open Access Journals (Sweden)

    Imran Majid

    2014-01-01

    Full Text Available Background: While laser resurfacing remains the most effective treatment option for atrophic acne scars, the high incidence of post-treatment adverse effects limits its use. Fractional laser photothermolysis attempts to overcome these limitations of laser resurfacing by creating microscopic zones of injury to the dermis with skip areas in between. Aim: The aim of the present study is to assess the efficacy and safety of fractional CO 2 laser resurfacing in atrophic facial acne scars. Materials and Methods: Sixty patients with moderate to severe atrophic facial acne scars were treated with 3-4 sessions of fractional CO 2 laser resurfacing at 6-week intervals. The therapeutic response to treatment was assessed at each follow up visit and then finally 6 months after the last laser session using a quartile grading scale. Response to treatment was labelled as ′excellent′ if there was >50% improvement in scar appearance and texture of skin on the grading scale while 25-50% response and <25% improvement were labelled as ′good′ and ′poor′ response, respectively. The overall satisfaction of the patients and any adverse reactions to the treatment were also noted. Results: Most of the patients showed a combination of different morphological types of acne scars. At the time of final assessment 6 months after the last laser session, an excellent response was observed in 26 patients (43.3% while 15 (25% and 19 patients (31.7% demonstrated a good and poor response respectively. Rolling and superficial boxcar scars responded the best while pitted scars responded the least to fractional laser monotherapy. The commonest reported adverse effect was transient erythema and crusting lasting for an average of 3-4 and 4-6 days, respectively while three patients developed post-inflammatory pigmentation lasting for 8-12 weeks. Conclusions: Fractional laser resurfacing as monotherapy is effective in treating acne scars especially rolling and superficial boxcar

  11. Case of acne conglobata successfully treated by CO(2) laser combined with topical tretinoin therapy.

    Science.gov (United States)

    Hasegawa, Toshio; Matsukura, Tomoyuki; Suga, Yasushi; Muramatsu, Shigenori; Mizuno, Yuki; Tsuchihashi, Hitoshi; Haruna, Kunitaka; Ogawa, Hideoki; Ikeda, Shigaku

    2007-08-01

    Acne conglobata is an uncommon disorder characterized by the presence of nodulocystic lesions. Conservative therapy with oral and topical antibiotics is of limited efficacy in many cases, and surgical excision is often needed for removal of the cystic lesions. Treatment is particularly difficult in cases with lesions located in aesthetically sensitive areas, such as the face. We successfully treated a case of acne conglobata by CO(2) laser ablation to remove the top of the sinuses and their tracts. In addition, topical tretinoin therapy was also initiated simultaneously to prevent the appearance of new acne lesions. Based on the results, we propose that the use of CO(2) laser for opening the cysts, combined with topical tretinoin therapy to prevent the appearance of new lesions, is a powerful treatment option for acne conglobata.

  12. CO2 Laser Surgery and Prosthetic Management for the Treatment of Epulis Fissuratum

    Science.gov (United States)

    de Arruda Paes-Junior, Tarcisio José; Cavalcanti, Sâmia Carolina Mota; Nascimento, Daniela Fernandes Figueira; Saavedra, Guilherme de Siqueira Ferreira Anzaloni; Kimpara, Estevão Tomomitsu; Borges, Alexandre Luiz Souto; Niccoli-Filho, Walter; Komori, Paula Carolina de Paiva

    2011-01-01

    The aim of this study was to present a case report of the surgical removal of hyperplasia in the oral cavity, using carbon dioxide (CO2) laser radiation and rehabilitation with a complete denture. Epulis fissuratum occurs in complete denture patients, because a constant irritative action induces the mucosa to grow under poorly fitting dentures. These lesions must be removed, and to avoid a relapse, new complete dentures should be made to maintain healthy surgical tissues. The clinical sequence presented in this case shows a completely edentulous patient with epulis fissuratum on the lower alveolar ridge extending to the vestibular sulcus of the anterior region of mandible. Immediate complete dentures were made prior to the lesion removal with CO2 laser radiation, providing satisfactory results in oral function and tissue health. PMID:21991461

  13. CO2 laser improves 45S5 bioglass interaction with dentin.

    Science.gov (United States)

    Bakry, A S; Takahashi, H; Otsuki, M; Sadr, A; Yamashita, K; Tagami, J

    2011-02-01

    Bioglass 45S5 is a bioactive glass that can create a layer of calcium-phosphate crystals on mineralized hard tissues. In this study, 45S5 bioglass was mixed with phosphoric acid and irradiated with CO(2) laser and examined as a possible aid in the treatment of dentin hypersensitivity. The dentinal surface modified by the aforementioned technique was chemically and micro-morphologically examined with a field emission scanning electron microscope (FE-SEM) equipped with an energy-dispersive x-ray spectroscope (EDS), and the crystalline structures of the examined dentinal surfaces were examined by x-ray diffraction (XRD). Moreover, the mechanical properties of the newly formed layer were examined by nanoindentation. The results showed that 45S5 bioglass could occlude the dentinal tubule orifices with calcium-phosphate crystals. The application of CO(2) laser potentially improved the mechanical organization of these crystals.

  14. Analysis of the heat affected zone in CO2 laser cutting of stainless steel

    Directory of Open Access Journals (Sweden)

    Madić Miloš J.

    2012-01-01

    Full Text Available This paper presents an investigation into the effect of the laser cutting parameters on the heat affected zone in CO2 laser cutting of AISI 304 stainless steel. The mathematical model for the heat affected zone was expressed as a function of the laser cutting parameters such as the laser power, cutting speed, assist gas pressure and focus position using the artificial neural network. To obtain experimental database for the artificial neural network training, laser cutting experiment was planned as per Taguchi’s L27 orthogonal array with three levels for each of the cutting parameter. Using the 27 experimental data sets, the artificial neural network was trained with gradient descent with momentum algorithm and the average absolute percentage error was 2.33%. The testing accuracy was then verified with 6 extra experimental data sets and the average predicting error was 6.46%. Statistically assessed as adequate, the artificial neural network model was then used to investigate the effect of the laser cutting parameters on the heat affected zone. To analyze the main and interaction effect of the laser cutting parameters on the heat affected zone, 2-D and 3-D plots were generated. The analysis revealed that the cutting speed had maximum influence on the heat affected zone followed by the laser power, focus position and assist gas pressure. Finally, using the Monte Carlo method the optimal laser cutting parameter values that minimize the heat affected zone were identified.

  15. High-pressure vapor-liquid equilibrium data for CO2-orange peel oil

    Directory of Open Access Journals (Sweden)

    G.R. Stuart

    2000-06-01

    Full Text Available Recently, there has been a growing interest in fractionating orange peel oil by the use of supercritical carbon dioxide (SCCO2. However, progress in this area has been hindered by the lack of more comprehensive work concerning the phase equilibrium behavior of the SCCO2-orange peel oil system. In this context, the aim of this work is to provide new phase equilibrium data for this system over a wide range of temperatures and pressures, permitting the construction of coexistence PT-xy curves as well as the P-T diagram. The experiments were performed in a high-pressure variable-volume view cell in the temperature range of 50-70ºC from 70 to 135 atm and in the CO2 mass fraction composition range of 0.35-0.98. Based on the experimental phase equilibrium results, appropriate operating conditions can be set for high-pressure fractionation purposes.

  16. Optical Probing of CO2 Laser-Plasma Interactions at Near Critical Density

    Science.gov (United States)

    Gong, Chao

    The interaction of a high-power laser beam with plasma has been explored extensively in the context of laser-driven fusion, plasma-based acceleration of ions and electrons and high energy-density physics. One of the fundamental processes common to all these studies is the penetration of intense light into a dense matter through the hole boring effect and self-induced transparency. Light with a given wavelength lambda will be reflected once the electron density equals the critical electron plasma density nc = 1.1x 1021cm -3 /[lambda(mum)]2. The radiation pressure exerted on the critical density layer is characterized by the ponderomotive force of a focused laser pulse which scales with a laser intensity, I as Ilambda2 Wmum2/cm 2. At Ilambda2 ˜1017 Wmum2/cm2 and above, it becomes possible for the laser pulse not only to steepen the plasma profile but to push the overcritical plasma with ne > nc creating a cavity or a hole in the target. The phenomenon of hole boring, whereby a laser pulse propagates through a reduced density cavity to reach and push the critical density layer, is of importance in fast-ignition fusion because it may allow the laser pulse to deliver its energy closer to the compressed fuel where it can be converted into fast electrons that are needed to ignite a small portion of the fuel. The layer of plasma pushed by the radiation pressure can reflect and accelerate ions via the so called Hole Boring Radiation Pressure Acceleration mechanism. Also the density pile- up in combination with the strong electron heating at the critical density layer can facilitate the formation of a collisionless shock. This shock wave acceleration can produce high energy ion beams with a narrow energy spread. Numerous experiments have been carried out to study dynamics of laser plasma interaction indirectly using solid state targets that are opaque for 1?m laser. However, by using a longer wavelength CO2 laser, lambda = 10.6mum, the critical plasma density is decreased

  17. Oral Crest Lengthening for Increasing Removable Denture Retention by Means of CO2 Laser

    Directory of Open Access Journals (Sweden)

    Samir Nammour

    2014-01-01

    Full Text Available The loss of teeth and their replacement by artificial denture is associated with many problems. The denture needs a certain amount of ridge height to give it retention and a long-term function. Crest lengthening procedures are performed to provide a better anatomic environment and to create proper supporting structures for more stability and retention of the denture. The purpose of our study is to describe and evaluate the effectiveness of CO2 laser-assisted surgery in patients treated for crest lengthening (vestibular deepening. There have been various surgical techniques described in order to restore alveolar ridge height by pushing muscles attaching of the jaws. Most of these techniques cause postoperative complications such as edemas, hemorrhage, pain, infection, slow healing, and rebound to initial position. Our clinical study describes the treatment planning and clinical steps for the crest lengthening with the use of CO2 laser beam (6–15 Watts in noncontact, energy density range: 84.92–212.31 J/cm2, focus, and continuous mode with a focal point diameter of 0.3 mm. At the end of each surgery, dentures were temporarily relined with a soft material. Patients were asked to mandatorily wear their relined denture for a minimum of 4–6 weeks and to remove it for hygienic purposes. At the end of each surgery, the deepest length of the vestibule was measured by the operator. No sutures were made and bloodless wounds healed in second intention without grafts. Results pointed out the efficiency of the procedure using CO2 laser. At 8 weeks of post-op, the mean of crest lengthening was stable without rebound. Only a loss of 15% was noticed. To conclude, the use of CO2 laser is an effective option for crest lengthening.

  18. Bactericidal effect of the CO2 laser in the root canal: an in-vitro study

    Science.gov (United States)

    Gutknecht, Norbert; Wilkert-Walter, Cornelia; Lampert, Friedrich

    1998-04-01

    The purpose of this study was to determine the bactericidal effect of a CO2 laser used in a continuous mode. Classically prepared root canals were irradiated under standardized conditions with power settings of 2, 4, and 6 Watts. The mean elimination of Enterococcus faecalis in prepared and infected root canals of extracted teeth was 98.97%, 99.51% and 99.34% respectively. Minimum elimination was 91.67% and maximum 99.696%.

  19. Experimental observation of parametric effects near period doubling in a loss-modulated CO2 laser

    OpenAIRE

    Chizhevsky, V. N.; Corbalán, R.

    1996-01-01

    A number of parametric effects, such as suppression of period doubling, shift of the bifurcation point, scaling law relating the shift and the perturbation amplitude, influence of the detuning on the suppression, reaching of the maximum gain between the original and shifted bifurcation points, and scaling law for idler power are experimentally observed near period doubling bifurcation in a loss-driven CO2 laser that is subjected to periodic loss perturbations at a frequency that is close to a...

  20. CO2 Laser Beat-Wave Experiment in an Unmagnetized Plasma

    Science.gov (United States)

    Liu, Fei; Hwang, David; Horton, Robert; Hong, Sean; Evans, Russell

    2012-10-01

    The ability to remotely generate plasma current in dense plasmas is a basic yet important investigation in experimental plasma physics and fusion energy research. It is even more advantageous if the wave penetration is independent of the electron acceleration process. Plasma current can be generated through beat-wave mixing process by launching two intense electromagnetic waves (φ>>φpe) into plasma. The beat wave formation process can be efficient if the difference frequency of the two pump waves is matched to a local resonant frequency of the medium, i.e. in this case the local plasma frequency. Beat wave can accelerate plasma electrons via quasi-linear Landau process, which has been demonstrated in a low-density plasma using microwaves.footnotetextRogers, J. H. and Hwang, D. Q., Phys. Rev. Lett. v68 p3877 (1992). The CO2 lasers provide the high tunability for the wave-particle interaction experiment at a variety of plasma densities with plasma frequency in THz range. Two sections of Lumonics TEA CO2 lasers have been modified to serve as the two pump wave sources with peak power over 100MW. The development of the tunable CO2 lasers, a high-density plasma target source and diagnostics system will be presented. The initial results of unbalanced beat-wave experiment using one high-power pulsed and one low-power CW CO2 lasers will be presented and discussed using the independent plasma source to control the φpe of the interaction region. This work is supported by U.S. DOE under Contract No. DE-FG02-10ER55083.

  1. Oral crest lengthening for increasing removable denture retention by means of CO2 laser.

    Science.gov (United States)

    Nammour, Samir; Gerges, Elie; Bou Tayeh, Rima; Zeinoun, Toni

    2014-01-01

    The loss of teeth and their replacement by artificial denture is associated with many problems. The denture needs a certain amount of ridge height to give it retention and a long-term function. Crest lengthening procedures are performed to provide a better anatomic environment and to create proper supporting structures for more stability and retention of the denture. The purpose of our study is to describe and evaluate the effectiveness of CO2 laser-assisted surgery in patients treated for crest lengthening (vestibular deepening). There have been various surgical techniques described in order to restore alveolar ridge height by pushing muscles attaching of the jaws. Most of these techniques cause postoperative complications such as edemas, hemorrhage, pain, infection, slow healing, and rebound to initial position. Our clinical study describes the treatment planning and clinical steps for the crest lengthening with the use of CO2 laser beam (6-15 Watts in noncontact, energy density range: 84.92-212.31 J/cm(2), focus, and continuous mode with a focal point diameter of 0.3 mm). At the end of each surgery, dentures were temporarily relined with a soft material. Patients were asked to mandatorily wear their relined denture for a minimum of 4-6 weeks and to remove it for hygienic purposes. At the end of each surgery, the deepest length of the vestibule was measured by the operator. No sutures were made and bloodless wounds healed in second intention without grafts. Results pointed out the efficiency of the procedure using CO2 laser. At 8 weeks of post-op, the mean of crest lengthening was stable without rebound. Only a loss of 15% was noticed. To conclude, the use of CO2 laser is an effective option for crest lengthening.

  2. Autonomous field measurements of CO2 in the atmospheric column with the miniaturized laser heterodyne radiometer (Mini-LHR)

    Science.gov (United States)

    Melroy, H. R.; Wilson, E. L.; Clarke, G. B.; Ott, L. E.; Mao, J.; Ramanathan, A. K.; McLinden, M. L.

    2015-09-01

    We present column CO2 measurements taken by the passive miniaturized laser heterodyne radiometer (Mini-LHR) at 1611.51 nm at the Mauna Loa Observatory in Hawaii. The Mini-LHR was operated autonomously, during the month of May 2013 at this site, working in tandem with an AERONET sun photometer that measures aerosol optical depth at 15-min intervals during daylight hours. Laser heterodyne radiometry has been used since the 1970s to measure atmospheric gases such as ozone, water vapor, methane, ammonia, chlorine monoxide, and nitrous oxide. This iteration of the technology utilizes distributed feedback lasers to produce a low-cost, small, portable sensor that has potential for global deployment. Applications of this instrument include supplementation of existing monitoring networks to provide denser global coverage, providing validation for larger satellite missions, and targeting regions of carbon flux uncertainty. Also presented here are preliminary retrieval analysis and the performance analysis that demonstrate that the Mini-LHR responds extremely well to changes in the atmospheric absorption.

  3. Autonomous Field Measurements of CO2 in the Atmospheric Column with the Miniaturized Laser Heterodyne Radiometer (Mini-LHR)

    Science.gov (United States)

    Melroy, H. R.; Wilson, E. L.; Clarke, G. B.; Ott, L. E.; Mao, J.; Ramanathan, A. K.; McLinden, M. L.

    2015-01-01

    We present column CO2 measurements taken by the passive Miniaturized Laser Heterodyne Radiometer (Mini-LHR) at 1611.51 nm at the Mauna Loa Observatory (MLO) in Hawaii. The Mini-LHR was operated autonomously, during the month of May 2013 at this site, working in tandem with an AERONET sun photometer that measures aerosol optical depth at 15 minute intervals during daylight hours. Laser Heterodyne Radiometry has been used since the 1970s to measure atmospheric gases such as ozone, water vapor, methane, ammonia, chlorine monoxide, and nitrous oxide. This iteration of the technology utilizes distributed feedback lasers to produce a low-cost, small, portable sensor that has potential for global deployment. Applications of this instrument include supplementation of existing monitoring networks to provide denser global coverage, providing validation for larger satellite missions, and targeting regions of carbon flux uncertainty. Also presented here is a preliminary retrieval analysis and the performance analysis that demonstrates that the Mini-LHR responds extremely well to changes in the atmospheric absorption.

  4. HRR TEA CO2 laser with 220W average output power

    Directory of Open Access Journals (Sweden)

    M. Zand

    2008-03-01

    Full Text Available In this study, the design and construction of a pulse high repetition rate (HRR, transverse atmospheric pressure (TEA CO2 laser with ultra violet preionization is presented. In this laser, normal pure, industrial gases and also a combination of spark and corona preionization are used. In semi-sealed off condition, we obtained 220 watts at 300 Hz, %7.7 efficiency, 735 mJ/pulse. The best records that we reached separately were 1.1 J/pulse, 320 Hz PRR, 11 MW peak power and 10.6% efficiency .

  5. Effect of the operating characteristics parameters on the performance of a waveguide CO2 laser

    Science.gov (United States)

    Mortazavi, Somayeh; Sajad, Batol; Jelvani, Saeid; Pazokian, Hedieh; Montazerolghaem, Mohsen; Naeimi, Saeid Amin

    2011-12-01

    In this paper, the influence of the operating parameters on the performance of a waveguide-CO2 laser was investigated. The output power versus discharge current, gas pressure, and gas mixture ratio were measured using a different tube design. Also, it is observed that the laser output wavelengths vary as the discharge current changes. The obtained maximum powers are ~14.5 W in a tube of diameter 3 mm and length 70 cm at the pressure 50 mbar, using the active medium with two discharge regions.

  6. Dispersion of light and heavy pollutants in urban scale models: CO(2) laser photoacoustic studies.

    Science.gov (United States)

    Zelinger, Z; Strizík, M; Kubát, P; Civis, S; Grigorová, E; Janecková, R; Zavila, O; Nevrlý, V; Herecová, L; Bailleux, S; Horká, V; Ferus, M; Skrínský, J; Kozubková, M; Drábková, S; Janour, Z

    2009-04-01

    The distribution of pollutants in two urban scale models (point emission source and street canyon with extensive transport) was investigated by means of CO(2) laser photoacoustic spectroscopy in the region of the atmospheric window (9-10 mum). The experimental results of physical modeling are in a good agreement with the numerical calculations performed in the frame of computational fluid dynamic (CFD) modeling. Methanol, ethanol, and ozone (examples of light pollutants), as well as sulfur hexafluoride and 1,2 dichlorethane (examples of heavy pollutants), were selected on the basis of their high resolution spectra acquired by Fourier transform and laser diode spectroscopy.

  7. Pulsed CO2 laser interaction with a metal surface at oblique incidence

    Science.gov (United States)

    McKay, J. A.; Schriempf, J. T.; Cronburg, T. L.; Eninger, J. E.; Woodroffe, J. A.

    1980-01-01

    Thermal fluence deposition and surface pressure generation produced by a CO2 laser pulse have been measured as a function of angle of incidence theta on sheet aluminum in air. The paper finds that air plasma ignition depends on the laser beam intensity I sub 0 only, not on the surface-normal flux (I sub 0)(cos theta). Conversely, the fluence deposition and surface pressure depend only on the product (I sub 0)(cos theta), and obey the square-root and two-thirds-power dependences observed with simple I sub 0 variation at normal incidence.

  8. Stark-effect modulation of a CO2 laser by NH2D.

    Science.gov (United States)

    Johnston, A. R.; Melville, R. D. S., Jr.

    1971-01-01

    Use of the molecular Stark effect in NH2D to modulate the 10.6-micron P(20) line of a CO2 laser, yielding a modulation depth of 40% from a 200-V/cm rms signal applied to a 19.7-cm gas cell external to the laser. NH2D was prepared by mixing ND3 and NH3. The absorption coefficient of the M = 4 Stark-split line was measured as a function of mixing ratio and pressure. The observed pressure-broadening coefficient was 32.5 MHz/torr.

  9. Two-color CO2/HeNe laser interferometer for C-2 experiment.

    Science.gov (United States)

    Gornostaeva, O; Deng, B H; Garate, E; Gota, H; Kinley, J; Schroeder, J; Tuszewski, M

    2010-10-01

    A six-channel two-color interferometer has been developed for plasma electron density measurements in the C-2 field reversed configuration experiment. A CO(2) laser is utilized as the main probe beams, while copropagating visible HeNe laser beams are mainly sensitive to vibration. Density measurements in C-2 plasmas have shown that this is a reliable turn-key system. The maximum residual phase noise after vibration compensation is less than ±5°, corresponding to a line integral density of 3×10(18) m(-2). The time resolution for routine operation is 2 μs.

  10. Evaluation of CO2 laser irradiation effect on enamel microhardness after incipient caries creation

    Directory of Open Access Journals (Sweden)

    Loghman Rezaei-Soufi

    2016-12-01

    Full Text Available Objective: The important mission in modern science of caries prevention is identification and providing the necessary actions for caries prevention to patients with an elevated risk of caries. The aim of this study was evaluation of CO2 laser irradiation effect on enamel microhardness after incipient caries creation. Material and methods: In this in vitro-experimental study, for evaluation of enamel microhardness 30 teeth after disinfection process were divided randomly into three groups A, B, C [n=10]: A] Control [normal saline] B] Immersed in cariogenic solution for 1 month C] Immersed in cariogenic solution for 1 month + CO2 laser [10.6µm, 10Hz, 0.5W, 20s, beam diameter 0.2 mm]. Data analyzing was used by 16 SPSS software. Parametric one-way ANOVA and Tukey were used for surface microhardness at 0.05% significance level. Results: According to one-way ANOVA parametric test, there was a significant difference between three groups [p=0.047]. In the following, results of Tukey test showed that there was a significant statistical difference between the microhardness of control and other groups [P=0.038]. On the other hand, there wasn’t statistical difference between A, C and B, C group means [P>0.05]. Conclusion: These study findings showed that CO2 laser irradiation on enamel surface with incipient caries had no significant effect on surface microhardness enhancement.

  11. Microstructure change in the interface of co2 laser welded zirconium alloys

    Science.gov (United States)

    Boutarek, N.; Azzougui, B.; Saidi, D.; Neggache, M.

    2009-11-01

    Welding is a joining procedure that offers some benefits over mechanical fasteners such as weight reduction and absence of notches induced by machining operations. CO2 laser beam welding with a continuous wave is a high energy density and low heat input process. The result of this is a small heat-affected zone (HAZ), which cools very rapidly with very little distortion, and a high depth-to-width ratio for the Welding is a necessary process during fabricating fuel rods and fuel assemblies with Zircaloy-4 cladding, and electron beam welding is one of the commonly- used method. In this work, the joining of zirconium alloys was attempted by laser beam welding. A 2 kW CO2 laser is used and the joints are obtained from similar materials, which are plates of Zircaloy-4 (2 mm thick). A series of zirconium alloys were welded and investigated in a tow-fold approach: (1) process optimisation: the laser processing parameters are optimized to obtain welds with minimum defects, and (2) material characterisation: weld microstructures were evaluated. The microstructure and the phases present in the resolidified zone of the laser -welded specimens were analyzed by optical and scanning electron microscopy, X-ray diffraction, and also by the realization of micro hardness diagrams. A particular attention was made to study the correlation between surface structure and mechanical behaviour.

  12. Thermo-mechanical simulations of CO2 laser-fused silica interactions

    Science.gov (United States)

    Doualle, T.; Gallais, L.; Cormont, P.; Hébert, D.; Combis, P.; Rullier, J.-L.

    2016-03-01

    CO2 laser heating of silica glass is used in many scientific and industrial applications. Particularly, localized CO2 laser heating of silica glass has demonstrated its ability to mitigate surface damage on optics used for high power laser applications. To develop such applications, the control of temperature, heat affected area, and resulting mechanical stresses are critical. Therefore, it is necessary to understand the silica transformation, the material ejection, and the thermo-mechanical stresses induced by the laser heating and subsequent cooling. In this paper, we detail the development of comprehensive thermo-mechanical numerical simulations of these physical processes, based on finite-element method. The approach is developed for 2D or 3D cases to tackle the case of a moving beam at the surface of the sample, and we particularly discuss the choice of the different parameters based on bibliographic inputs. The thermal and mechanical numerical results have been compared to different dedicated experimental studies: infrared thermography measurements at the surface of the irradiated area, optical profilometry measurements of the laser-processed sites, and photo-elastic measurements. Very consistent results are obtained between numerical and experimental results for the description of the temperature gradients, the material ejection, and the residual stresses.

  13. Feasibility study of a CO2-laser based lightning-protection system realization

    Science.gov (United States)

    Apollonov, Victor V.

    2005-01-01

    The feasibility of producing a continuous laser spark (CLS) with low resistance by focusing radiation from a CO2 laser with a conic mirror is demonstrated. The laser energy input per unit length required for this is experimentally found to be equal to ≈200 J/m. The possibility to efficiently control the trajectory of an electric discharge by means of a CLS is demonstrated. The effect of polarity in the electric breakdown of the air gaps between the CLS plasma channel and a metal rod is discovered and interpreted. The transverse structure of CLS conductivity is investigated. The possibility of producing a long laser spark (LLS) with much higher resistance by focusing radiation from a CO2 laser with a spherical mirror used to protect objects against lightning is studied. The conditions under which the electric discharges from clouds can be guided reproducibly along a LLS are determined. Experiments reveal that the interaction between the LLS and the discharge from an electrode (lightning rod) leads to a decrease in the lifetime of the streamer corona burst, as well as to an increase in the current of the developing leader and its velocity compared to the case without the LLS.

  14. The stable gastric pentadecapeptide BPC 157, given locally, improves CO2 laser healing in mice.

    Science.gov (United States)

    Bilic, M; Bumber, Z; Blagaic, A Boban; Batelja, L; Seiwerth, S; Sikiric, P

    2005-05-01

    The stable gastric pentadecapeptide BPC 157 (GEPPPGKPADDAGLV; mol. wt. 1419), which is at present in phase II clinical trials for the treatment of inflammatory bowel disease, has been shown to counteract healing impairment by systemic corticosteroids in burned mice, both in vivo and in vitro, in the absence of carrier or protease inhibitor. Because of the particular healing problems associated with laser use, we have now studied the effect of pentadecapeptide BPC 157 on CO(2) laser injuries (Sharplan 1075 laser: 20 W, distance 12.5 cm, spot size 0.8 mm and exposure time 1s) created on the dorsal skin of anaesthetised male NMRI-Hannover mice. The injury was either not treated or treated by topical application of a thin layer of neutral cream containing pentadecapeptide BPC 157 (1 microg, 1 ng or 1 pg (dissolved in saline)/g) or vehicle only, once daily, with the first application 60 min after injury and the last 24 h before killing (1, 7 and 21 days after the laser application). BPC 157 consistently improved healing after the CO(2) laser injury, both macroscopically and microscopically. The effect was produced with a simple method of application and favourable peptide stability (no carrier), and confirms the effectiveness of an ointment containing 1 microg BPC 157 (dissolved in saline)/g neutral cream.

  15. Synthesis, microstructure and phase control of zirconium tungstate with a CO2 laser

    Science.gov (United States)

    Liang, E. J.; Wu, T. A.; Yuan, B.; Chao, M. J.; Zhang, W. F.

    2007-05-01

    Zirconium tungstate was successfully synthesized by rapid solidification with a CO2 laser. Scanning electron microscope observation shows that nano-threads/rods grew horizontally on the surface region and vertically in the interior. The nano-threads in the interior are composed of densely packed nano-crystallites. Raman spectroscopic study shows that the samples solidified in an orthorhombic structure when the laser scan speed was >=2 mm s-1. This is explained by a compressive stress induced during the rapid solidification process due to a sudden drop of temperature from the molten pool to the ambient. The possibilities for tuning the strength of the compressive stress and controlling the production of different phases of ZrW2O8 are proposed. It is analysed and confirmed that the compressive stress can be effectively reduced by lowering laser scan speed. ZrW2O8 samples with cubic structure are produced with laser scan speed <2 mm s-1.

  16. Fabrication of Nanostructured Omniphobic and Superomniphobic Surfaces with Inexpensive CO2Laser Engraver.

    Science.gov (United States)

    Pendurthi, Anudeep; Movafaghi, Sanli; Wang, Wei; Shadman, Soran; Yalin, Azer P; Kota, Arun K

    2017-08-09

    Superomniphobic surfaces (i.e., surfaces that are extremely repellent to both high surface tension liquids like water and low surface tension liquid like oils) can be fabricated through a combination of surface chemistry that imparts low solid surface energy with a re-entrant surface texture. Recently, surface texturing with lasers has received significant attention because laser texturing is scalable, solvent-free, and can produce a monolithic texture on virtually any material. In this work, we fabricated nanostructured omniphobic and superomniphobic surfaces with a variety of materials using a simple, inexpensive and commercially available CO 2 laser engraver. Further, we demonstrated that the nanostructured omniphobic and superomniphobic surfaces fabricated using our laser texturing technique can be used to design patterned surfaces, surfaces with discrete domains of the desired wettability, and on-surface microfluidic devices.

  17. Pulse shaping of transversely excited atmospheric CO2 laser using a simple plasma shutter

    Science.gov (United States)

    Hurst, Noah; Harilal, S. S.

    2009-03-01

    The pulse from a transversely excited atmospheric CO2 laser consists of a sharp spike followed by a long, drawn out tail region spanning about 2-5 μs caused by the nitrogen gas in the laser cavity. The nitrogen tail is undesirable in many applications because it decreases the average power of the laser pulse. We employ a pinhole plasma shutter for eliminating the nitrogen tail and shortening the pulse width. The pinhole shutter optically triggers plasma at a certain point in time with respect to the temporal profile of the laser pulse. This way, a good portion of the sharp spike is transmitted, while the energy stored in the nitrogen tail is consumed in heating the plasma. This simplistic plasma shutter is easy to build and inexpensive compared to other existing plasma shutter designs.

  18. Skin resurfacing improved with a new dual wavelength Er:YAG/CO2 laser system: a comparative study.

    Science.gov (United States)

    Trelles, M A; García-Solana, L; Calderhead, R G

    1999-06-01

    The efficacy of a new dual wavelength Er:YAG and CO2 laser system was tested for skin resurfacing results on rabbits' ears and human facial skin. The dual wavelength laser delivers simultaneous pulses of low-energy CO2 and high-energy Er:YAG energies. Theoretically, combining the strengths of both laser types in one console should lead to improved clinical outcome. The use of the laser for skin resurfacing and remodeling has dramatically increased over the past few years. The CO2 laser was the first laser to be used in this field, followed more recently by the E:YAG laser. Both lasers offer unique advantages and disadvantages. The present study consists of an ear chamber experiment, conducted on eight rabbits, to examine vascular network formation, after laser resurfacing with a standard CO2 laser and the Er:YAG/CO2 laser. Resurfacing was also performed on human patients with the Er:YAG/CO2 laser and the results were compared with previously published results of CO2 laser resurfacing. Significant advantages, including an attenuation in the degree of edema and erythema and a shorter reepithelialization time compared to results with conventional CO2 systems, were observed with the Er:YAG/CO2 system. Improved tissue reorganization and good clinical results in nine of the ten patients (six ratings of "very good" and three "good") were observed. The clinical outcome of the remaining patient was rated as "fair." Minimal side effects were reported and observed in only three patients. The learning curve required to maximize the efficiency of the system is steep, however, requiring a thorough understanding of the different laser/tissue interactions associated with the two wavelengths. It is the authors' opinion that the dual wavelength Er:YAG/CO2 laser system offers a particularly efficient and flexible system to perform standard CO2 procedures for skin resurfacing with an improved clinical outcome, as well as other applications with the CO2 or Er:YAG energy delivered

  19. Analysis of therapeutical effects of Er:YAG and CO2 laser post treatments of small hemangiomas

    Science.gov (United States)

    Remlová, E.; Vránová, J.; Rosina, J.; Navrátil, L.

    2011-09-01

    The main goal of our study was the evaluation of treatment efficiency of two types of ablative laser-CO2 and Er:YAG (or ERB) treatment. 183 patients (Er:YAG—105 patients, CO2—78 patients) were analyzed to compare the curative effects and adverse events, such as loss of pigment and appearance of scars caused by these two lasers. The results of the study showed the slightly better effectiveness of Er:YAG laser radiation in comparison with CO2 laser in the case of treatment of small hemangiomas up to 3 mm in diameter. In the Er:YAG laser application the curative effect was in 99%, hypo-pigmentation occurred in 18%, and scars in 70% of all treatments. In the CO2 laser application the curative effect was in 97%, hypo-pigmentation in 52%, and scars in 77% from all treatments.

  20. Advanced 2-micron Solid-state Laser for Wind and CO2 Lidar Applications

    Science.gov (United States)

    Yu, Jirong; Trieu, Bo C.; Petros, Mulugeta; Bai, Yingxin; Petzar, Paul J.; Koch, Grady J.; Singh, Upendra N.; Kavaya, Michael J.

    2006-01-01

    Significant advancements in the 2-micron laser development have been made recently. Solid-state 2-micron laser is a key subsystem for a coherent Doppler lidar that measures the horizontal and vertical wind velocities with high precision and resolution. The same laser, after a few modifications, can also be used in a Differential Absorption Lidar (DIAL) system for measuring atmospheric CO2 concentration profiles. The world record 2-micron laser energy is demonstrated with an oscillator and two amplifiers system. It generates more than one joule per pulse energy with excellent beam quality. Based on the successful demonstration of a fully conductive cooled oscillator by using heat pipe technology, an improved fully conductively cooled 2-micron amplifier was designed, manufactured and integrated. It virtually eliminates the running coolant to increase the overall system efficiency and reliability. In addition to technology development and demonstration, a compact and engineering hardened 2-micron laser is under development. It is capable of producing 250 mJ at 10 Hz by an oscillator and one amplifier. This compact laser is expected to be integrated to a lidar system and take field measurements. The recent achievements push forward the readiness of such a laser system for space lidar applications. This paper will review the developments of the state-of-the-art solid-state 2-micron laser.

  1. Safety and efficacy of high fluence CO2 laser skin resurfacing with a single pass.

    Science.gov (United States)

    Khosh, M M; Larrabee, W F; Smoller, B

    1999-01-01

    Carbon dioxide (CO2) laser skin resurfacing has nearly replaced more traditional methods of superficial skin rejuvenation. Post-treatment erythema is the most common side effect of this method of skin resurfacing. Sublethal thermal damage to the dermis has been proposed as an etiology for post laser erythema. Recent developments in laser resurfacing technology have aimed at minimizing thermal damage to the dermis. To determine depth of skin ablation, extent of thermal injury, and ideal laser parameters for the FeatherTouch laser system. To assess the safety and efficacy of laser resurfacing at high energy fluences with a single pass. Laser resurfacing was performed in the preauricular skin of five patients undergoing rhytidectomy. A total of 60 sites were tested with fluences of 7 to 17 Joules/cm2. Histologic evaluation of excised skin showed maximal thermal injury to be restricted to 60 microns in the papillary dermis. The reticular dermis showed no evidence of injury. Based on these findings, laser resurfacing at 17 J/cm2 (70 watts) was performed on 30 patients (in the periorbital area, a maximum of 9 J/cm2 or 36 watts was used). Follow up ranged between 12 and 18 months. Based on histologic comparison of average and high fluence laser resurfacing, high fluence laser resurfacing did not cause added thermal damage to the reticular dermis. In the clinical group, no major complications such as scarring, scleral show, infection or ectropion were encountered. Transient hyperpigmentation was noted in three patients. Overall patient satisfaction was good to excellent. Post-treatment erythema lasted an average of 4 weeks. We conclude that CO2 laser resurfacing of the face (excluding the periorbital region) can be performed safely and effectively, with the FeatherTouch laser, at 17 J/cm2 with one pass. In our group of patients, laser resurfacing with a single pass at 17 J/cm2 caused less post-operative erythema than two or more passes at 9 J/cm2.

  2. Effects of CO2 laser irradiation on tooth enamel coated with biofilm.

    Science.gov (United States)

    Cohen, Julie; Featherstone, John D B; Le, Charles Q; Steinberg, Doron; Feuerstein, Osnat

    2014-03-01

    CO2 laser irradiation of tooth enamel can inhibit demineralization of tooth enamel, by changing enamel composition and resistance to acid attack. The aim of this work was to examine these effects of CO2 laser irradiation on enamel covered by biofilm. Streptococcus mutans was grown on bovine enamel surfaces for 48 hours to form a mature biofilm. Samples were irradiated by CO2 laser (wavelength of 10.6 µm) at a power of 0.08 W in a super-pulse mode for 1 second and 24 pulses/second, with an energy density of 0.77 J/cm(2) per pulse. Untreated controls and laser treated samples with and without biofilm were examined for the morphology of the biofilm and the enamel surface by scanning electron microscopy (SEM). Structural biofilm viability was assessed using confocal laser scanning microscopy with live/dead staining. The biofilm was removed in a sonication water bath and the non-treated and irradiated enamel samples were chemically analyzed using energy dispersive X-ray spectrometry (EDS) and Fourier transform infrared spectroscopy (FTIR). Irradiated samples showed a melt zone with micro-cracks in the center of the irradiating beam position, which was smaller when irradiated enamel was covered by biofilm. Confocal microscopy images demonstrated higher proportion of dead bacteria at the margins of the irradiated spot area, while at the spot center the bacteria were evaporated exposing the enamel surface to direct laser irradiation. EDS analysis showed an increase in Ca/P ratio after irradiation of enamel covered with biofilm. FTIR analysis showed an approximately 40% carbonate loss in the irradiated enamel samples, including those with biofilms. Biofilms protect enamel surfaces from possible morphological irradiation damage without interfering with the resultant chemical changes that may increase the enamel resistance to acid attack. Therefore, under certain exposure regimens that are thermally and mechanically safe for enamel, CO2 laser irradiation of

  3. A 4 U Laser Heterodyne Radiometer for Methane (CH4) and Carbon Dioxide (CO2) Measurements from an Occultation-Viewing CubSat

    Science.gov (United States)

    Wilson, Emily L.; DiGregorio, A. J.; Riot, Vincent J.; Ammons, Mark S.; Bruner, WIlliam W.; Carter, Darrell; Mao, Jianping; Ramanathan, Anand; Strahan, Susan E.; Oman, Luke D.; hide

    2017-01-01

    We present a design for a 4 U (20 cm 20 cm 10 cm) occultation-viewing laser heterodyne radiometer (LHR) that measures methane (CH4), carbon dioxide (CO2) and water vapor(H2O) in the limb that is designed for deployment on a 6 U CubeSat. The LHR design collects sunlight that has undergone absorption by the trace gas and mixes it with a distributive feedback (DFB) laser centered at 1640 nm that scans across CO2, CH4, and H2O absorption features. Upper troposphere lower stratosphere measurements of these gases provide key inputs to stratospheric circulation models: measuring stratospheric circulation and its variability is essential for projecting how climate change will affect stratospheric ozone.

  4. LASER PHYSICS: Characteristics of a high-pressure CO2 laser with ultraviolet preionization by surface channel discharges

    Science.gov (United States)

    Kolesnikov, Yu A.; Kotov, A. A.

    1987-07-01

    A surface channel discharge was used as the source of ultraviolet radiation for pulse-periodic photoionization of CO2 laser mixtures. This source was sufficiently powerful to ensure a volume discharge at pressures of ~5 atm necessary for continuous tuning of the emission frequency. Experiments on the use of this source in a laser showed that it could be used at pressures up to 3 atm and in this range the input energy density was 500 J/liter, the output energy density was ~30 J/liter, and the actual output energy in the form of laser radiation was 2.3 J.

  5. In situ study of the anticariogenic potential of fluoride varnish combined with CO2 laser on enamel.

    Science.gov (United States)

    Souza-Gabriel, Aline Evangelista; Turssi, Cecília Pedroso; Colucci, Vivian; Tenuta, Lívia Maria Andaló; Serra, Mônica Campos; Corona, Silmara Aparecida Milori

    2015-06-01

    This in situ study evaluated the effect of fluoride varnish combined with CO2 laser in controlling enamel demineralization caused by cariogenic challenges. In a crossover study conducted in 2 phases of 14 days each, 14 volunteers (n = 14) wore palatal appliances with bovine enamel slabs treated with fluoride varnish + CO2 laser (FV + CO2), fluoride varnish (FV), nonfluoride placebo varnish (PV) and nonfluoride placebo varnish + CO2 laser (PV + CO2). Drops of sucrose solution were dripped onto enamel slabs allowing the accumulation of biofilm. At the first phase, half of the volunteers received 4 enamel slabs treated with FV while the remainders received slabs exposed to the PV with and without CO2 laser. In the second phase, the vonlunteers were reversed treatments. The slabs were evaluated for cross-sectional microhardness (CSMH) and the concentration of loosely bound fluoride (CaF2) and firmly bound fluoride (FAp). The concentration of fluoride in biofilm were also determined. Two-way ANOVA showed that the CSMH values were higher in laser-irradiated enamel, regardless of the fluoride varnish. Friedman test showed that FV group presented significantly larger amount of fluoride in biofilm (P CO2, which was not different from FV (P > 0.05). The synergistic effect of fluoride varnish and CO2 laser on enamel demineralization was not observed, however, CO2 laser reduces enamel demineralization. CO2 laser might reduce the demineralization of subsurface enamel, although its association with a high concentrated fluoride therapy may not result in a positive synergistic interaction. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Assessment of radicular dentin permeability after irradiation with CO2 laser and endodontic irrigation treatments with thermal imaging

    Science.gov (United States)

    Cho, Heajin; Lee, Robert C.; Chan, Kenneth H.; Fried, Daniel

    2017-02-01

    Previous studies have demonstrated that the permeability changes due to the surface modification of dentin can be quantified via thermal imaging during dehydration. The CO2 laser has been shown to remove the smear layer and disinfect root canals. Moreover, thermal modification via CO2 laser irradiation can be used to convert dentin into a highly mineralized enamel-like mineral. The purpose of this study is to evaluate the radicular dentin surface modification after CO2 laser irradiation by measuring the permeability with thermal imaging. Human molar specimens (n=12) were sectioned into 4 axial walls of the pulp chamber and treated with either 10% NaClO for 1 minute, 5% EDTA for 1 minute, CO2 laser or none. The CO2 laser was operated at 9.4 μm with a pulse duration of 26 μs, pulse repetition rate of 300 Hz and a fluence of 13 J/cm2. The samples were dehydrated using an air spray for 60 seconds and imaged using a thermal camera. The resulting surface morphological changes were assessed using 3D digital microscopy. The images from digital microscopy confirmed melting of the mineral phase of dentin. The area enclosed by the time-temperature curve during dehydration, ▵Q, measured with thermal imaging increased significantly with treatments with EDTA and the CO2 laser (P<0.05). These results indicate that the surface modification due to CO2 laser treatment increases permeability of radicular dentin.

  7. Microhardness evaluations of CAD/CAM ceramics irradiated with CO2or Nd:YAP laser.

    Science.gov (United States)

    El Gamal, Ahmed; Rocca, Jean Paul; Fornaini, Carlo; Medioni, Etienne; Brulat-Bouchard, Nathalie

    2017-03-31

    The aim of this study was to measure the microhardness values of irradiated computer-aided design/computer-aided manufacturing (CAD/CAM) ceramics surfaces before and after thermal treatment. Sixty CAD/CAM ceramic discs were prepared and grouped by material, i.e. lithium disilicate ceramic (Emax CAD) and zirconia ceramic (Emax ZirCAD). Laser irradiation at the material surface was performed with a carbon dioxide laser at 5 Watt (W) or 10 W power in continuous mode (CW mode), or with a neodymium:yttrium aluminum perovskite (Nd:YAP) laser at 10 W on graphite and non-graphite surfaces. Vickers hardness was tested at 0.3 kg f for lithium disilicate and 1 kg f for zirconia. Emax CAD irradiated with CO 2 at 5 W increased microhardness by 6.32 GPa whereas Emax ZirCAD irradiated with Nd:YAP decreased microhardness by 17.46 GPa. CO 2 laser effectively increases the microhardness of lithium disilicate ceramics (Emax CAD).

  8. [New treatment possibilities for skin changes with the CO2 laser in head and neck surgery].

    Science.gov (United States)

    Sedlmaier, B; Fuhrer, A; Jovanovic, S

    1997-08-01

    Laser treatment of various skin changes has become common clinical practice in recent years. Due to its physical properties, the CO2 laser is particularly well suited for cutting and ablating tissue. The high absorption of its wavelength in water (lambda = 10600 nm) is responsible for its low penetration depth in biological tissue. Shortening the exposure time minimizes thermal side effects, such as carbonization and coagulation. This effect can be lessened with the Silk Touch scanner, since the focussed laser beam is moved over a defined area by rapidly rotating mirrors. This enables a controlled and reliable removal of various dermal lesions. Particularly well-suited for treatment hypertrophic scars, post-acne scarring, perioral and periorbital wrinkles, rhinophymas and benign neoplasms including verruca vulgaris. Cosmetically favorable reepithelialization of the treated skin surfaces occurs within a very short time after treatment. Periorbital resurfacing and correction of a rhinophyma are used as examples of dermal treatment with the CO2 laser and the Silk Touch scanner.

  9. Outcome assessment in patients with chronic obstructive rhinitis CO2 laser treated

    Science.gov (United States)

    Testa, D; Motta, G; Galli, V; Iovine, R; Guerra, G; Marenzi, G; Testa, B

    2006-01-01

    Summary Surgical lasers have been used to restore nasal flow in chronic obstructive rhinitis, with a significant improvement in symptoms having been reported in almost all cases. However, evidence supporting the efficacy at long-term, and studies on the assessment of quality of life remain limited. In the present study, efficacy at long term and improvement in the quality of life were assessed in patients with chronic obstructive rhinitis, treated with CO2 laser. A total of 308 patients with chronic obstructive rhinitis were enrolled. The primary outcome measure assessed was the change in score regarding specific and general symptoms, between baseline to 2-4.5 and 7.8 mean years follow-up. Laser turbinotomy restored nasal flow and induced a change in total score which was statistically significant, for specific and general symptoms at the first, second and third follow-up, p < 0.01. CO2 laser turbinate surgery improved symptoms and quality of life in patients with chronic obstructive rhinitis as observed at 2-4.5 and 7.8 mean years follow-up. PMID:18383755

  10. CO2 laser myringoplasty: a minimally invasive technique for treating tympanic membrane atelectasis.

    Science.gov (United States)

    Ryan, Marisa; Kaylie, David

    2013-12-01

    1) To describe a cost-effective, minimally invasive technique for treating tympanic membrane atelectasis, and 2) to present data on hearing improvement in patients receiving this as the basis for a future prospective study. Report of hearing and clinical outcome over a 4-year period. Tertiary center. Patients with tympanic membrane atelectasis and hearing loss. Valsalva, hydrodissection, or manual dissection reinflated the atelectatic segment under mask anesthesia. A CO2 laser hand-held fiber contracted the tympanic membrane. Then, myringotomy and pressure equalizing tube placement was performed. Status of the tympanic membrane, patency of the tubes, and pure tone average air-bone gap on preoperative, postoperative, and most recent audiograms. Laser myringoplasty was performed on 60 ears of 43 patients. The average preoperative air-bone gap was 15 dB, and this significantly improved to 7 dB (p elevation did not have significant hearing improvement. Laser myringoplasty for treatment of tympanic membrane atelectasis using a hand-held flexible fiber CO2 laser is feasible and may improve hearing immediately and long term. It is not useful in severe adherent atelectasis. More studies are indicated to confirm its overall cost-effectiveness and competitiveness with traditional methods of managing atelectasis.

  11. Transformation of hydroxyapatite to fluorapatite by irradiation with high-energy CO2 laser.

    Science.gov (United States)

    Meurman, J H; Hemmerlé, J; Voegel, J C; Rauhamaa-Mäkinen, R; Luomanen, M

    1997-01-01

    High-energy laser irradiation has been shown to cause crystalline transformations in apatites, which may lead to the formation of tricalcium phosphates with a resulting decrease in acid resistance. Depending on the nature and energy density of laser irradiation used, however, an increase of acid resistance of dental enamel has also been reported after laser irradiation. The aim of the present study was to investigate the phase transformation of hydroxyapatite (HA) to fluorapatite (FA) in a model system that incorporates sodium fluoride (NaF) into apatite structure by using laser irradiation. A CO2 laser was used at energy densities ranging from 21 to 500 J/cm2. Synthetic HA mixed with NaF (10:1) was the target of laser irradiation. The crystalline structures were then investigated using X-ray diffraction analysis. The results showed that a phase transformation of HA to FA could be realized, and that the threshold energy density needed was 38 J/cm2. Not only is the finding crystallographically important, but it also opens new perspectives for future research regarding the development of laser technology for clinical purposes.

  12. High-pressure continuously tunable CO2 lasers and molecular laser ...

    Indian Academy of Sciences (India)

    2014-01-05

    Jan 5, 2014 ... The acronym MLIS (molecular laser isotope separation) defines the laser process whereby the isotopes of uranium can be separated by mid-infrared laser/s when the molecule employed is UF6. The theoretical and spectroscopical data to configure and enable experiments and demonstrations in the ...

  13. Surface treatment of dental porcelain: CO2 laser as an alternative to oven glaze.

    Science.gov (United States)

    Sgura, Ricardo; Reis, Mariana Cavalcante; Hernandes, Antonio Carlos; de Abreu Fantini, Márcia Carvalho; Andreeta, Marcello Rubens Barsi; Medeiros, Igor Studart

    2015-02-01

    This work tested continuous CO2 laser as a surface treatment to dental porcelain and compared it to oven glaze (auto-glaze) by means of roughness and color parameters. Three commercial veneering porcelains with different crystalline content were tested: VM7, VM9, and VM13. Porcelain discs (3.5 × 2.0 mm, diameter × height) were sintered and had one side ground by a diamond bur (45 μm) simulating a chairside adjustment in a clinical office. Specimens (n = 7) were divided into the following groups: C--control (no treatment), G--auto-glaze (oven), and L--surface continuous irradiation with CO2 laser (Gem Laser, Coherent; λ = 10.6 μm). Laser was tested in three exposure times (3, 4, or 5 min) and two irradiances (45 and 50 W/cm(2)). Roughness parameters (Ra, Rz, and Rpm/Rz) were measured using a rugosimeter (Surftest 301, Mitutoyo). Color differences (ΔE) between the G and L groups were calculated (VITA Easyshade); ΔE values up to 3.3 were considered as not perceivable. A surface analysis was conducted by stereomicroscopy (Olympus SZ61) and SEM (Stereoscan 440, LEO). Crystalline content of specimens from groups C and L (50 W/cm(2), 5 min) was assessed by X-ray diffraction and then compared. Surface roughness (Ra and Rz) observed for laser-irradiated groups was similar to G for all studied porcelains. Rpm/Rz ratios were near 1.0 for all groups that indicated a sharp ridge profile for all specimens. Only one laser condition studied (50 W/cm(2), 3 min) from VM7 porcelain resulted in color difference (ΔE = 3.5) to G. Specimens irradiated with 50 W/cm(2) for 5 min presented the smoother surface observed by SEM, comparable to G. X-ray diffraction data revealed an increase in leucite crystallite size for VM9 and VM13 porcelains after laser treatment. Regarding roughness, continuous CO2 laser applied on porcelain surface was as effective as conventional oven auto-glaze.

  14. Laser induced fluorescence in nanosecond repetitively pulsed discharges for CO2 conversion

    Science.gov (United States)

    Martini, L. M.; Gatti, N.; Dilecce, G.; Scotoni, M.; Tosi, P.

    2018-01-01

    A CO2 nanosecond repetitively pulsed discharge (NRP) is a harsh environment for laser induced fluorescence (LIF) diagnostics. The difficulties arise from it being a strongly collisional system in which the gas composition, pressure and temperature, have quick and strong variations. The relevant diagnostic problems are described and illustrated through the application of LIF to the measurement of the OH radical in three different discharge configurations, with gas mixtures containing CO2 + H2O. These range from a dielectric barrier NRP with He buffer gas, a less hostile case in which absolute OH density measurement is possible, to an NRP in CO2+H2O, where the full set of drawbacks is at work. In the last case, the OH density measurement is not possible with laser pulses and detector time resolution in the ns time scale. Nevertheless, it is shown that with a proper knowledge of the collisional rate constants involved in the LIF process, a collisional energy transfer-LIF methodology is still applicable to deduce the gas composition from the analysis of LIF spectra.

  15. Fabrication of gold and silver nanoparticles with pulsed laser ablation under pressurized CO2

    Science.gov (United States)

    Machmudah, Siti; Wahyudiono; Takada, Noriharu; Kanda, Hideki; Sasaki, Koichi; Goto, Motonobu

    2013-12-01

    Pulsed laser ablation (PLA) has become a promising method for the synthesis of nanoclusters for photonics, electronics and medicine. In this work PLA in pressurized CO2 has been applied for fabrication of gold and silver nanoparticles. Laser ablation was performed with an excitation wavelength of 532 nm under various pressures (0.1-20 MPa), temperatures (40-80 °C) of CO2 medium and ablation times (1500-9000 s). On the basis of the experimental result, it follows that structures of gold (Au) and silver (Ag) nanoparticles were significantly affected by the changes in CO2 density. The structures of gold and silver nanoparticles also changed with an increase of ablation time. From a field-emission scanning electron microscopy (FE-SEM) image of the fabricated gold nano-structured particles on silicon wafer, it was seen that a network structure of smaller gold particles was fabricated. A similar morphology of particles fabricated from silver plate was observed. Silver particles contain nanoparticles with large-varied diameter ranging from 5 nm to 1.2 μm. The mechanism of nanoparticles fabrication could be observed as follows. Bigger gold/silver particles melted during the ablation process and then ejected smaller spherical nanoparticles, which formed nanoclusters attached on the molten particles.

  16. Fractional CO2 laser treatment for vulvovaginal atrophy symptoms and vaginal rejuvenation in perimenopausal women

    Directory of Open Access Journals (Sweden)

    Arroyo C

    2017-08-01

    Full Text Available César Arroyo HM Montepríncipe University Hospital Laser Unit, Madrid, Spain Background: This study investigated a novel fractional carbon dioxide (CO2 laser for treatment of symptoms associated with vulvovaginal atrophy (VVA in perimenopausal women.Methods: The study included 21 perimenopausal women (mean age 45±7 years treated three times by CO2 laser resurfacing and coagulation of the vaginal canal tissue and mucosal tissue of the introitus. Vaginal health index (VHI scores were computed by the investigator at baseline and follow-ups. Subjects reported on sexual function, satisfaction, and improvement with treatment. A visual analog scale was used to measure discomfort with treatment.Results: Vaginal health and subject assessment of vaginal symptoms improved with successive treatments. At 12 weeks following the third treatment, 82% of the patients showed a statistically significant improvement in VHI (P<0.05. Additionally, 81% of subjects reported improvement in sexual gratification, 94% reported improvement in vaginal rejuvenation, and 100% reported satisfaction with treatment. VHI improvement remained significant at 6–8 months after treatments (P<0.01. Most patients (97% reported no to mild discomfort with treatment. Responses were mild and transient following treatment, with itching being the most commonly reported (20% side effect.Conclusion: In this study, fractional CO2 laser treatment was associated with improvement of vaginal health and amelioration of symptoms of VVA, resulting in improved sexual function in perimenopausal women. Treatment time was quick, and there was minimal discomfort associated with treatment. Investigation of clinical outcome in a larger study population is warranted. Keywords: genitourinary syndrome of menopause, vaginal rejuvenation, stress urinary incontinence, collagen remodeling, sexual dysfunction, vulvovaginal atrophy

  17. TREATMENT OF CONDYLOMATA ACUMINATA AND BOWENOID PAPULOSIS WITH CO2 LASER AND IMIQUIMOD.

    Directory of Open Access Journals (Sweden)

    Ilko Bakardzhiev

    2012-05-01

    Full Text Available Some of the most common manifestation of Human Papilloma Virus (HPV infection in venereology are Condylomata acuminata and Bowenoid Papulosis. These diseases are often difficult to diagnose by dermatologists, obstetricians, gynecologists and urologists. This article represents our entire clinical experience with the use of carbon dioxide (CO-2 laser in the treatment of 58 (40 male and 18 female patients with Condylomata Acuminata after other treatments had failed. Successful eradication was accomplished in 53 patients with wide distribution of condylomatous lesions, with 88% per cent responding to a single laser treatment. In our experience there are no side effects, damage to the surrounding tissue is minimal and the lesions have not reccured. In 82.3% of the patients the treatment resulted in complete disappearance of the lesions, whereas in the other two to three percent treatments were required. The advantages of the laser treatment are discussed in this article.

  18. Real-time near IR (1310 nm) imaging of CO2 laser ablation of enamel.

    Science.gov (United States)

    Darling, Cynthia L; Fried, Daniel

    2008-02-18

    The high-transparency of dental enamel in the near-IR (NIR) can be exploited for real-time imaging of ablation crater formation during drilling with lasers. NIR images were acquired with an InGaAs focal plane array and a NIR zoom microscope during drilling incisions in human enamel samples with a lambda=9.3-microm CO(2) laser operating at repetition rates of 50-300-Hz with and without a water spray. Crack formation, dehydration and thermal changes were observed during ablation. These initial images demonstrate the potential of NIR imaging to monitor laser-ablation events in real-time to provide information about the mechanism of ablation and to evaluate the potential for peripheral thermal and mechanical damage.

  19. Process control in continuous high-power CO2 laser beam welding

    Science.gov (United States)

    Seidel, Bernd; Beersiek, Jorg; Beyer, Eckhard

    1994-09-01

    The use of high power CO2 lasers in welding enables processing with high laser intensities at the workpiece which is connected with the formation of a laser induced plasma at the surface of the workpiece. Therefore the effect of deep penetration welding by formation of a plasma filled keyhole and plasma plume above the workpiece is possible, including the risk of plasma shielding, which means strong absorption of the incident laser beam above the workpiece and thus interruption of the welding process. The conditions for ignition of plasma shielding, which is determined by electron density, are mainly influenced by laser intensity, process gas and material. Variations of these parameters have been conducted in order to find limits for the appearance of plasma shielding. Experimental data are used to verify a model concerning the absorption mechanism of a stationary shielding plasma state. The dynamic behavior is treated by time resolved spectroscopic analysis of the light emitted by the plasma above the workpiece yielding monitoring signals that have a strong correlation with the formation of plasma shielding. Based on these investigations a closed-loop process control in continuous high power laser welding has been developed. Using the intensity of a spectral line of laser induced plasma as monitoring signal and the regulation of laser intensity via laser power, plasma shielding can be suppressed. From the industrial point of view increase in economy and reliability of the laser welding process combined with quality improvements which are induced by the application of the plasma shielding controller (PSC) are of great importance. For this reason three examples of PSC application are presented.

  20. Selective Laser Ablation of Carious Lesions using Simultaneous Scanned Near-IR Diode and CO2 Lasers.

    Science.gov (United States)

    Chan, Kenneth H; Fried, Daniel

    2017-01-28

    Previous studies have established that carious lesions can be imaged with high contrast using near-IR wavelengths coincident with high water absorption, namely 1450-nm, without the interference of stains. It has been demonstrated that computer-controlled laser scanning systems utilizing IR lasers operating at high pulse repetition rates can be used for serial imaging and selective removal of caries lesions. In this study, a point-to-point scanning system was developed integrating a 1450-nm diode laser with the CO2 ablation laser. This approach is advantageous since it does not require an expensive near-IR camera. In this pilot study, we demonstrate the feasibility of a combined NIR and IR laser system for the selective removal of carious lesions.

  1. Contribution to the beam plasma material interactions during material processing with TEA CO2 laser radiation

    Science.gov (United States)

    Jaschek, Rainer; Konrad, Peter E.; Mayerhofer, Roland; Bergmann, Hans W.; Bickel, Peter G.; Kowalewicz, Roland; Kuttenberger, Alfred; Christiansen, Jens

    1995-03-01

    The TEA-CO2-laser (transversely excited atmospheric pressure) is a tool for the pulsed processing of materials with peak power densities up to 1010 W/cm2 and a FWHM of 70 ns. The interaction between the laser beam, the surface of the work piece and the surrounding atmosphere as well as gas pressure and the formation of an induced plasma influences the response of the target. It was found that depending on the power density and the atmosphere the response can take two forms. (1) No target modification due to optical break through of the atmosphere and therefore shielding of the target (air pressure above 10 mbar, depending on the material). (2) Processing of materials (air pressure below 10 mbar, depending on the material) with melting of metallic surfaces (power density above 0.5 109 W/cm2), hole formation (power density of 5 109 W/cm2) and shock hardening (power density of 3.5 1010 W/cm2). All those phenomena are usually linked with the occurrence of laser supported combustion waves and laser supported detonation waves, respectively for which the mechanism is still not completely understood. The present paper shows how short time photography and spatial and temporal resolved spectroscopy can be used to better understand the various processes that occur during laser beam interaction. The spectra of titanium and aluminum are observed and correlated with the modification of the target. If the power density is high enough and the gas pressure above a material and gas composition specific threshold, the plasma radiation shows only spectral lines of the background atmosphere. If the gas pressure is below this threshold, a modification of the target surface (melting, evaporation and solid state transformation) with TEA-CO2- laser pulses is possible and the material specific spectra is observed. In some cases spatial and temporal resolved spectroscopy of a plasma allows the calculation of electron temperatures by comparison of two spectral lines.

  2. CO2 laser stapedotomy safety: influence of laser energy and time on bone-conduction hearing levels.

    Science.gov (United States)

    Schönfeld, Uwe; Weiming, Hu; Hofmann, Veit M; Jovanovic, Sergije; Albers, Andreas E

    2017-10-11

    Total laser energy in CO2 stapedotomy depends on the laser settings and the amount of applications. It is unclear if the amount of total laser energy affects bone-conduction hearing thresholds and if possible effects are temporary or permanent. Alterations of bone-conduction hearing thresholds after single or multiple-shot CO2 laser stapedotomy were analyzed between 1 and 3 weeks and 1.5-6 months after primary (n = 501) or revision surgeries (n = 153) and correlated to time, laser energy, frequency, surgical technique, and pathology encountered in revision stapedotomy. In both time periods, most patients showed a lower bone-conduction threshold in the four-tone puretone average (PTA) at frequencies of 0.5, 1, 2, and 3 kHz that further improved over time. Between 1 and 3 weeks, the improvement was significant in subgroups with cumulative energies lower 1 J and successful one-shot technique or in revisions without laser application. The remaining subgroups with higher total energies showed significant improvements between 1.5 and 6 months. At 4 and 8 kHz, significant improvements were found during 1.5-6 months after primary and revision surgery independent of the used energy. Repeated CO2 laser applications showed no impairment in bone-conduction thresholds and can thus be considered as safe. In most patients, significant, yet unexplained, improvements in bone-conduction hearing thresholds were noticed in a time- and energy-related pattern.

  3. Isotope selective analysis of CO(2) with tunable diode laser (TDL) spectroscopy in the NIR.

    Science.gov (United States)

    Horner, Gerald; Lau, Steffen; Kantor, Zoltan; Lohmannsroben, Hans-Gerd

    2004-08-01

    The performance of a home-built tunable diode laser (TDL) spectrometer, aimed at multi-line detection of carbon dioxide, has been evaluated and optimized. In the regime of the (30(0)1)(III) spectroscopy with balanced detection in a long-path absorption cell set-up. High sensitivity in conjunction with high precision -- typically +/-1 (per thousand) and +/-6 (per thousand) for 3% and 0.7% of CO(2), respectively -- renders this experimental approach a promising analytical concept for isotope-ratio determination of carbon dioxide in soil and breath gas. For a moderate (12)CO(2) line, the pressure dependence of the line profile was characterized in detail, to account for pressure effects on sensitive measurements.

  4. Selective bond breaking of CO2 in phase-locked two-color intense laser fields: laser field intensity dependence.

    Science.gov (United States)

    Endo, Tomoyuki; Fujise, Hikaru; Kawachi, Yuuna; Ishihara, Ayaka; Matsuda, Akitaka; Fushitani, Mizuho; Kono, Hirohiko; Hishikawa, Akiyoshi

    2017-02-01

    Selective bond breaking of CO2 in phase-locked ω-2ω two-color intense laser fields (λ = 800 nm and 400 nm, total field intensity I ∼ 10(14) W cm(-2)) has been investigated by coincidence momentum imaging. The CO(+) and O(+) fragment ions produced by two-body Coulomb explosion, CO2(2+) → CO(+) + O(+), exhibit asymmetric distributions along the laser polarization direction, showing that one of the two equivalent C-O bonds is selectively broken by the laser fields. At a field intensity higher than 2 × 10(14) W cm(-2), the largest fragment asymmetry is observed when the relative phase ϕ between the ω and 2ω laser fields is ∼0 and π. On the other hand, an increase of the asymmetry and a shift of the phase providing the largest asymmetry are observed at lower field intensities. The selective bond breaking and its dependence on the laser field intensity are discussed in terms of a mechanism involving deformation of the potential energy surfaces and electron recollision in intense laser fields.

  5. Multipass-prism interferometer for fine-frequency-tuning, single-mode operation of TEA CO(2) lasers.

    Science.gov (United States)

    Giuliani, G; Palange, E; Salvetti, G

    1984-09-01

    A novel interferometric configuration has been used as an efficient, narrow-band output coupler for high-power lasers. Its application to a TEA CO(2) laser has resulted in extremely reliable (100%) single transverse- and longitudinal-mode operation of this laser with a fine-frequency tunability of up to 3 GHz.

  6. Clinical and histologic effects from CO2 laser treatment of keloids.

    Science.gov (United States)

    Nicoletti, Gianfranco; De Francesco, Francesco; Mele, Carmine Michele; Cataldo, Chiara; Grella, Roberto; Brongo, Sergio; Accardo, Marina; Ferraro, Giuseppe Andrea; D'Andrea, Francesco

    2013-05-01

    Keloids and hypertrophic scars are abnormal responses to wound healing. In general, keloids exhibit a proliferative growth beyond the margins of the scar and remain persistent; while hypertrophic scars are contained to the original wound and may regress over time. In particular, keloid formation is one of the most challenging clinical problems, with increasing frequency in surgical practice. Many treatments are available such as intralesional corticosteroids, topical applications, cryotherapy, surgical excision, radiation therapy, silicone gel sheeting, pressure therapy, and laser therapy. There are no set guidelines for the treatment of keloids and the most common treatments are individualized and depended on the distribution, size, thickness, and consistency of lesions. The authors have evaluated carbon dioxide laser successfully in the treatment of keloids and the aim of this study was to determine the immediate and long-term histologic and clinical effects of keloids after carbon dioxide laser. Fifty consecutive patients (40 females, 10 males, ages 18-60 years, mean age 40 years) with moderate to severe keloids were evaluated. All the patients received regional treatments (deltoid, elbow, chin, and ear) in an outpatient setting with a high-energy pulsed CO2 laser. Significant immediate and prolonged clinical improvement in skin tone, texture, and appearance of carbon dioxide laser was examined in all patients. Dermal remodeling was observed also on histologic examination of biopsied tissue after treatment. Carbon dioxide laser appears to be effective and well tolerated for the treatment of keloids, avoiding the adverse effects and lengthy recovery time.

  7. Thermal infrared laser heterodyne spectroradiometry for solar occultation atmospheric CO2 measurements

    Science.gov (United States)

    Hoffmann, Alex; Macleod, Neil A.; Huebner, Marko; Weidmann, Damien

    2016-12-01

    This technology demonstration paper reports on the development, demonstration, performance assessment, and initial data analysis of a benchtop prototype quantum cascade laser heterodyne spectroradiometer, operating within a narrow spectral window of ˜ 1 cm-1 around 953.1 cm-1 in transmission mode and coupled to a passive Sun tracker. The instrument has been specifically designed for accurate dry air total column, and potentially vertical profile, measurements of CO2. Data from over 8 months of operation in 2015 near Didcot, UK, confirm that atmospheric measurements with noise levels down to 4 times the shot noise limit can be achieved with the current instrument. Over the 8-month period, spectra with spectral resolutions of 60 MHz (0.002 cm-1) and 600 MHz (0.02 cm-1) have been acquired with median signal-to-noise ratios of 113 and 257, respectively, and a wavenumber calibration uncertainty of 0.0024 cm-1.Using the optimal estimation method and RFM as the radiative transfer forward model, prior analysis and theoretical benchmark modelling had been performed with an observation system simulator (OSS) to target an optimized spectral region of interest. The selected narrow spectral window includes both CO2 and H2O ro-vibrational transition lines to enable the measurement of dry air CO2 column from a single spectrum. The OSS and preliminary retrieval results yield roughly 8 degrees of freedom for signal (over the entire state vector) for an arbitrarily chosen a priori state with relatively high uncertainty ( ˜ 4 for CO2). Preliminary total column mixing ratios obtained are consistent with GOSAT monthly data. At a spectral resolution of 60 MHz with an acquisition time of 90 s, instrumental noise propagation yields an error of around 1.5 ppm on the dry air total column of CO2, exclusive of biases and geophysical parameters errors at this stage.

  8. HIGH-PRESSURE VAPOR-LIQUID EQUILIBRIUM DATA FOR BINARY AND TERNARY SYSTEMS FORMED BY SUPERCRITICAL CO2, LIMONENE AND LINALOOL

    Directory of Open Access Journals (Sweden)

    MELO S. A. B. VIEIRA DE

    1999-01-01

    Full Text Available The feasibility of deterpenating orange peel oil with supercritical CO2 depends on relevant vapor-liquid equilibrium data because the selectivity of this solvent for limonene and linalool (the two key components of the oil is of crucial importance. The vapor-liquid equilibrium data of the CO2-limonene binary system was measured at 50, 60 and 70oC and pressures up to 10 MPa, and of the CO2-linalool binary system at 50oC and pressures up to 85 bar. These results were compared with published data when available in the literature. The unpublished ternary phase equilibrium of CO2-limonene-linalool was studied at 50oC and up to 9 MPa. Selectivities obtained using these ternary data were compared with those calculated using binary data and indicate that a selective separation of limonene and linalool can be achieved.

  9. Simulation and initial experiments of a high power pulsed TEA CO2 laser

    Science.gov (United States)

    Torabi, R.; Saghafifar, H.; Koushki, A. M.; Ganjovi, A. A.

    2016-01-01

    In this paper, the output characteristics of a UV pin array pre-ionized TEA CO2 laser have been simulated and compared with the associated experimental data. In our simulation, a new theoretical model has been improved for transient behavior analysis of the discharge current pulse. The laser discharge tube was modeled by a nonlinear RLC electric circuit as a real model for electron density calculation. This model was coupled with a six-temperature model (6TM) in order to simulation dynamic emission processes of the TEA CO2 laser. The equations were solved numerically by the fourth order Runge-Kutta numerical method and some important variables such as current and voltage of the main discharge, resistance of the plasma column and electron density in the main discharge region, were calculated as functions of time. The effects of non-dissociation factor, rotational quantum number and output coupler reflectivity were also studied theoretically. The experimental and simulation results are in good agreement.

  10. A new modality for minimally invasive CO2 laser surgery: flexible hollow-core photonic bandgap fibers.

    Science.gov (United States)

    Shurgalin, Max; Anastassiou, Charalambos

    2008-01-01

    Carbon dioxide (CO2) lasers have become one of the most common surgical lasers due to excellent tissue interaction properties that offer precise control of cutting and ablation depth, minimal thermal damage to surrounding tissue, and good hemostasis. However, realization of the benefits offered by using surgical CO2 lasers in many endoscopic, minimally invasive surgical procedures has been inhibited by the absence of reliable, flexible fiber laser beam delivery systems. Recently, novel hollow-core photonic bandgap optical fibers for CO2 lasers were developed that offer high flexibility and mechanical robustness with good optical performance under tight bends. These fibers can be used through rigid and flexible endoscopes and various handpieces and will allow surgeons to perform delicate and precise laser surgery procedures in a minimally invasive manner. This paper describes the basic design of laser beam delivery system, different surgical fiber designs and their characteristics, and usage with existing surgical CO2 laser models. A few examples of successful CO2 laser surgeries performed with these fibers are presented.

  11. GAS AND LIQUID LASERS: Optimization of the conditions for energy extraction from a coupled-mode gasdynamic CO2 laser

    Science.gov (United States)

    Odintsov, A. I.; Fedoseev, A. I.; Fomenko, L. A.

    1988-05-01

    A simplified model is considered of the physical processes occurring in the resonator zone of a gasdynamic laser emitting due to one of the vibrational transitions between levels of coupled CO2 modes. The energy characteristics of the laser are calculated and the energy extraction conditions are optimized for different active mixture parameters at the resonator input. An optimal energy extraction length is defined for a gasdynamic channel of constant cross section. The method developed is used to calculate the optimal nozzle profile in the resonator zone. Numerical calculations are made for CO2-Ar mixtures in which lasing takes place due to a transition with a wavelength of 18.4 μm.

  12. Fabrication Quality Analysis of a Fiber Optic Refractive Index Sensor Created by CO2 Laser Machining

    Directory of Open Access Journals (Sweden)

    Wei-Te Wu

    2013-03-01

    Full Text Available This study investigates the CO2 laser-stripped partial cladding of silica-based optic fibers with a core diameter of 400 μm, which enables them to sense the refractive index of the surrounding environment. However, inappropriate treatments during the machining process can generate a number of defects in the optic fiber sensors. Therefore, the quality of optic fiber sensors fabricated using CO2 laser machining must be analyzed. The results show that analysis of the fiber core size after machining can provide preliminary defect detection, and qualitative analysis of the optical transmission defects can be used to identify imperfections that are difficult to observe through size analysis. To more precisely and quantitatively detect fabrication defects, we included a tensile test and numerical aperture measurements in this study. After a series of quality inspections, we proposed improvements to the existing CO2 laser machining parameters, namely, a vertical scanning pathway, 4 W of power, and a feed rate of 9.45 cm/s. Using these improved parameters, we created optical fiber sensors with a core diameter of approximately 400 μm, no obvious optical transmission defects, a numerical aperture of 0.52 ± 0.019, a 0.886 Weibull modulus, and a 1.186 Weibull-shaped parameter. Finally, we used the optical fiber sensor fabricated using the improved parameters to measure the refractive indices of various solutions. The results show that a refractive-index resolution of 1.8 × 10−4 RIU (linear fitting R2 = 0.954 was achieved for sucrose solutions with refractive indices ranging between 1.333 and 1.383. We also adopted the particle plasmon resonance sensing scheme using the fabricated optical fibers. The results provided additional information, specifically, a superior sensor resolution of 5.73 × 10−5 RIU, and greater linearity at R2 = 0.999.

  13. Fabrication quality analysis of a fiber optic refractive index sensor created by CO2 laser machining.

    Science.gov (United States)

    Chen, Chien-Hsing; Yeh, Bo-Kuan; Tang, Jaw-Luen; Wu, Wei-Te

    2013-03-26

    This study investigates the CO2 laser-stripped partial cladding of silica-based optic fibers with a core diameter of 400 μm, which enables them to sense the refractive index of the surrounding environment. However, inappropriate treatments during the machining process can generate a number of defects in the optic fiber sensors. Therefore, the quality of optic fiber sensors fabricated using CO2 laser machining must be analyzed. The results show that analysis of the fiber core size after machining can provide preliminary defect detection, and qualitative analysis of the optical transmission defects can be used to identify imperfections that are difficult to observe through size analysis. To more precisely and quantitatively detect fabrication defects, we included a tensile test and numerical aperture measurements in this study. After a series of quality inspections, we proposed improvements to the existing CO2 laser machining parameters, namely, a vertical scanning pathway, 4 W of power, and a feed rate of 9.45 cm/s. Using these improved parameters, we created optical fiber sensors with a core diameter of approximately 400 μm, no obvious optical transmission defects, a numerical aperture of 0.52 ± 0.019, a 0.886 Weibull modulus, and a 1.186 Weibull-shaped parameter. Finally, we used the optical fiber sensor fabricated using the improved parameters to measure the refractive indices of various solutions. The results show that a refractive-index resolution of 1.8 × 10(-4) RIU (linear fitting R2 = 0.954) was achieved for sucrose solutions with refractive indices ranging between 1.333 and 1.383. We also adopted the particle plasmon resonance sensing scheme using the fabricated optical fibers. The results provided additional information, specifically, a superior sensor resolution of 5.73 × 10(-5) RIU, and greater linearity at R2 = 0.999.

  14. CO2-laser ablation of Bi-Sr-Ca-Cu oxide by millisecond pulse lengths

    Science.gov (United States)

    Meskoob, M.; Honda, T.; Safari, A.; Wachtman, J. B.; Danforth, S.; Wilkens, B. J.

    1990-03-01

    We have achieved ablation of Bi-Sr-Ca-Cu oxide from single targets of superconducting pellets by CO2-laser pulses of l ms length to grow superconducting thin films. Upon annealing, the 6000-Å thin films have a Tc (onset) of 90 K and zero resistance at 78 K. X-ray diffraction patterns indicate the growth of single-phase thin films. This technique allows growth of uniform single-phase superconducting thin films of lateral area greater than 1 cm2.

  15. CO2 laser-grooved long period fiber grating temperature sensor system based on intensity modulation.

    Science.gov (United States)

    Wang, Yi-Ping; Wang, Dong Ning; Jin, Wei

    2006-11-01

    A long period fiber grating (LPFG) temperature sensor system based on intensity modulation is developed. The LPFG employed is fabricated by the use of a focused CO2 laser beam to carve periodic grooves on the fiber. The temperature measurement resolution of up to 0.1 degrees C has been obtained within the temperature range between 20 degrees C and 100 degrees C. The system uses a simple intensity measurement method and exhibits the advantages of convenient intensity measurement, double temperature sensitivity, high resolution, simple configuration, and low cost.

  16. Recurrence rate and patient satisfaction of CO2 laser evaporation of lesions in patients with hidradenitis suppurativa

    DEFF Research Database (Denmark)

    Mikkelsen, Peter Riis; Dufour, Deirde Nathalie; Zarchi, Kian

    2015-01-01

    : To determine the recurrence rate, time to recurrence, and factors influencing disease recurrence in skin treated with CO2 laser evaporation, and healing by secondary intention; and patients' satisfaction with treatment. METHODS: Fifty-eight patients treated with CO2 laser evaporation were interviewed regarding...... recurrence and satisfaction after a mean of 25.7 months. RESULTS: Seventeen of 58 (29%) reported recurrence of HS lesions within the borders of the treated areas after a mean of 12.7 months. Obesity was a risk factor for recurrence with a hazard ratio of 4.53. Fifty-five patients (95%) reported some or great...... improvement, and 91% would recommend the CO2 laser surgery to other HS patients. CONCLUSION: This study supports the claim that CO2 laser treatment is an effective modality for recurrent HS lesions in a majority of patients. The authors identified obesity as a risk factor for recurrence. Self...

  17. Laser photoacoustic detection of the essential oil vapors of thyme, mint, and anise

    Science.gov (United States)

    El-Kahlout, A. M.; Al-Jourani, M. M.; Abu-Taha, M. I.; Laine, Derek C.

    1998-07-01

    Photoacoustic studies of the vapors of the essential oils of thyme, mint and anise have been made using a line-tunable waveguide CO2 laser in conjunction with a heat-pipe type of photoacoustic vapor sample cell operated over the temperature range 20 - 180 degree(s)C. Identifying spectral fingerprint features are found in the 9 - 10 micrometers spectral region for each of the three essential oils investigated. The principal features of the photoacoustic spectrum of each essential oil are associated with the dominant chemicals present i.e. thymol in thyme oil, menthol in mint and anethole in anise.

  18. Surface hardening using cw CO2 laser: laser heat treatment, modelation, and experimental work

    Science.gov (United States)

    Muniz, German; Alum, Jorge

    1996-02-01

    In the present work are given the results of the application of laser metal surface hardening techniques using a cw carbon dioxide laser as an energy source on steel 65 G. The laser heat treatment results are presented theoretically and experimentally. Continuous wave carbon dioxide laser of 0.6, 0.3, and 0.4 kW were used. A physical model for the descriptions of the thermophysical laser metal interactions process is given and a numerical algorithm is used to solve this problem by means of the LHT code. The results are compared with the corresponding experimental ones and a very good agreement is observed. The LHT code is able to do predictions of transformation hardening by laser heating. These results will be completed with other ones concerning laser alloying and cladding presented in a second paper.

  19. Jaw-opening reflex after CO2 laser stimulation of the perioral region in man.

    Science.gov (United States)

    Cruccu, G; Romaniello, A

    1998-02-01

    CO2 laser pulses selectively excite A-delta and C mechano-thermal nociceptors in the superficial layers of the skin. To study the jaw-opening reflex elicited by a purely nociceptive input, we delivered laser pulses to the perioral region in 15 subjects. Sensory threshold was very low (9 mJ/mm2). High-intensity noxious laser pulses (more than 4 x sensory threshold) evoked a single phase of electromyogram suppression (laser silent period, LSP) at an onset latency of 70 ms in the contracted masseter and temporal muscles, bilaterally. Even maximum-intensity laser pulses failed to activate the suprahyoid muscles. The recovery curves to paired laser stimuli showed that at short interstimulus intervals the test LSP was strongly suppressed. At about 380 ms it recovered to 50%, i.e. its recovery curve resembled that of the masseter late silent period after electrical mental nerve stimulation (SP2). In experiments studying the interaction with heterotopic stimuli and non-nociceptive responses, chin-taps or electrical shocks delivered to the supraorbital, infraorbital or mental nerves before laser stimulation strongly suppressed the LSP. A preceding perioral laser pulse strongly suppressed the masseter SP evoked by supraorbital stimulation and the SP2 evoked by mental stimulation, but left SPI unaffected. We conclude that the perioral A-delta fibre input elicits a jaw-opening reflex simply by inhibiting the jaw-closers. The LSP response is mediated by a multisynaptic chain of brainstem interneurons and shares with the masseter SP2 part of the central circuit in the ponto-medullary region. We also propose that a common centre processes the various inputs for jaw opening.

  20. Histological and SEM analysis of root cementum following irradiation with Er:YAG and CO2 lasers.

    Science.gov (United States)

    Almehdi, Aslam; Aoki, Akira; Ichinose, Shizuko; Taniguchi, Yoichi; Sasaki, Katia M; Ejiri, Kenichiro; Sawabe, Masanori; Chui, Chanthoeun; Katagiri, Sayaka; Izumi, Yuichi

    2013-01-01

    Recently, the Er:YAG and CO(2) lasers have been applied in periodontal therapy. However, the characteristics of laser-irradiated root cementum have not been fully analyzed. The aim of this study was to precisely analyze the alterations of root cementum treated with the Er:YAG and the CO(2) lasers, using non-decalcified thin histological sections. Eleven cementum plates were prepared from extracted human teeth. Pulsed Er:YAG laser contact irradiation was performed in a line at 40 mJ/pulse (14.2 J/cm(2)/pulse) and 25 Hz (1.0 W) under water spray. Continuous CO(2) laser irradiation was performed in non-contact mode at 1.0 W, and ultrasonic instrumentation was performed as a control. The treated samples were subjected to stereomicroscopy, scanning electron microscopy (SEM), light microscopy and SEM energy dispersive X-ray spectroscopy (SEM-EDS). The Er:YAG laser-treated cementum showed minimal alteration with a whitish, slightly ablated surface, whereas CO(2) laser treatment resulted in distinct carbonization. SEM analysis revealed characteristic micro-irregularities of the Er:YAG-lased surface and the melted, resolidified appearance surrounded by major and microcracks of the CO(2)-lased surface. Histological analysis revealed minimal thermal alteration and structural degradation of the Er:YAG laser-irradiated cementum with an affected layer of approximately 20-μm thickness, which partially consisted of two distinct affected layers. The CO(2)-lased cementum revealed multiple affected layers showing different structures/staining with approximately 140 μm thickness. Er:YAG laser irradiation used with water cooling resulted in minimal cementum ablation and thermal changes with a characteristic microstructure of the superficial layer. In contrast, CO(2) laser irradiation produced severely affected distinct multiple layers accompanied by melting and carbonization.

  1. Multiple-pulse irradiation of dental hard tissues at CO2 laser wavelengths

    Science.gov (United States)

    Fried, Daniel; Glena, Richard E.; Featherstone, John D. B.; Seka, Wolf D.

    1995-05-01

    Surface temperatures were monitored using pulsed photothermal radiometry (PPTR) during multiple pulse carbon dioxide laser irradiation ((lambda) equals 9.3, 9.6, 10.3 and 10.6 micrometers ). Permanent changes in the optical properties (reflectance and absorption) were observed at fluences greater than 2 J/cm2 for dentin and 5 J/cm2 for enamel. The laser irradiation changes the thermal and the optical properties of these tissues, substantially changing the energy deposition for subsequent laser pulses. The temperature response of enamel and dentin and the reflectance of dentin changed considerably with successive laser pulses. After 10 to 50 pulses the surface stabilized and no further changes were noted. Scanning electron micrographs of the laser conditioned surfaces showed large crystals of modified hydroxyapatite (approximately equals 500 nm) devoid of the organic matrix. Presumably, the water and the interwoven biopolymer matrix had been carbonized nd vaporized. Caries inhibition measurements after multiple pulse irradiation of enamel indicate that the stable laser conditioned surface is more resistant to acid dissolution than untreated enamel.

  2. Rapid and low-cost fabrication of polystyrene-based molds for PDMS microfluidic devices using a CO2 laser

    KAUST Repository

    Li, Huawei

    2011-11-01

    In this article, we described a rapid and low-cost method to fabricate polystyrene molds for PDMS microfluidic devices using a CO2 laser system. It takes only several minutes to fabricate the polystyrene mold with bump pattern on top of it using a CO2 laser system. The bump pattern can be easily transferred to PDMS and fabricate microchannles as deep as 3μm on PDMS. © (2012) Trans Tech Publications, Switzerland.

  3. Potential of CO2 lasers (10.6 µm associated with fluorides in inhibiting human enamel erosion

    Directory of Open Access Journals (Sweden)

    Thayanne Monteiro RAMOS-OLIVEIRA

    2014-01-01

    Full Text Available This in vitro study aimed to investigate the potential of CO2 lasers associated with different fluoride agents in inhibiting enamel erosion. Human enamel samples were randomly divided into 9 groups (n = 12: G1-eroded enamel; G2-APF gel; G3-AmF/NaF gel; G4-AmF/SnF2 solution; G5-CO2 laser (λ = 10.6 µm+APF gel; G6-CO2 laser+AmF/NaF gel; G7-CO2laser+AmF/SnF2solution; G8-CO2 laser; and G9-sound enamel. The CO2 laser parameters were: 0.45 J/cm2; 6 μs; and 128 Hz. After surface treatment, the samples (except from G9 were immersed in 1% citric acid (pH 4.0, 3 min. Surface microhardness was measured at baseline and after surface softening. The data were statistically analyzed by one-way ANOVA and Tukey’s tests (p < 0.05. G2 (407.6 ± 37.3 presented the highest mean SMH after softening, followed by G3 (407.5 ± 29.8 and G5 (399.7 ± 32.9. Within the fluoride-treated groups, G4 (309.0 ± 24.4 had a significantly lower mean SMH than G3 and G2, which were statistically similar to each other. AmF/NaF and APF application showed potential to protect and control erosion progression in dental enamel, and CO2 laser irradiation at 0.45J/cm2 did not influence its efficacy. CO2 laser irradiation alone under the same conditions could also significantly decrease enamel erosive mineral loss, although at lower levels.

  4. Parameters Influence of CO2 Laser on Cutting Quality of Polymer Materials

    Directory of Open Access Journals (Sweden)

    Robert Cep

    2016-09-01

    Full Text Available The article deals with evaluating of the resulting surface state of the three plastic materials and identification of suitable conditions for laser cutting with CO2 tube. As representative were chosen polypropylene, polymethylmethacrylate and polyamide. When cutting these types of materials it could melt eventually their re-sintering. A suitable combination of parameters is possible to achieve of sufficient quality of the cut. The samples were cut at different feed speed and laser power. Then they was compared on the basis of the measured roughness parameters Ra a Rz by using a portable touch roughness Hommel-Etamic W5 and dates was processed according to ČSN EN ISO 4287. Cutting of samples was realized at the Department of Machining, Assembly and Engineering Metrology, VŠB-TUO.

  5. The potential of CO2 laser photoacoustic spectrometry for detection of methanol in alcoholic beverage

    Science.gov (United States)

    Lin, J.-W.; Shaw, S.-Y.

    2009-03-01

    The first use of CO2 laser photoacoustic measurements for detecting the methanol contents in alcohol-like solutions is presented. With an intracavity cell configuration, the minimum detectable concentration was ˜200 ppm for methanol and the linear range of the calibration curve for methanol was from 200 to 70000 ppm. For demonstrating the reliability of analysis in alcoholic beverages, a series of different concentrations of two-component samples was prepared and measured by the same procedures. The results showed the feasibility on determining methanol and ethanol contents accurately within a specific tolerance, limited mainly by background signal and laser stability. This potential method with no pre-treatment of samples takes only ˜10 min to finish one single measurement. It suggests that the PA detection is suitable for routine diagnosis of adulterated wines in commercial products.

  6. Studies of long-life pulsed CO2 laser with Pt/SnO2 catalyst

    Science.gov (United States)

    Sidney, Barry D.

    1987-01-01

    Closed-cycle CO2 laser testing with and without a catalyst and with and without CO addition indicate that a catalyst is necessary for long-term operation. Initial results indicate that CO addition with a catalyst may prove optimal, but a precise gas mix has not yet been determined. A long-term run of 10 to the 6th power pulses using 1.3% added CO and a 2% Pt on SnO2 catalyst yields an efficiency of about 95% of open-cycle steady-state power. A simple mathematical analysis yields results which may be sufficient for determining optimum running conditions. Future plans call for testing various catalysts in the laser and longer tests, 10 to the 7th power pulses. A Gas Chromatograph will be installed to measure gas species concentration and the analysis will be slightly modified to include neglected but possibly important parameters.

  7. Single-frequency TEA CO2 laser with a bleaching spectral intracavity filter

    Science.gov (United States)

    Sorochenko, V. R.

    2017-02-01

    The regime of single-frequency operation is realised in a TEA CO2 laser with a spectral filter inside the cavity (a cell filled with SF6) on P(12)-P(24) lines of the 10P band. The minimal scatter of the peak powers of the laser pulses in a series of ‘shots’ and the maximal ratio of the output energies in the single-frequency and free running regimes (greater than 0.84) are obtained on the P(16) line at an optimal SF6 pressure in the cell. Experimental results qualitatively agree with the absorption spectrum of SF6 calculated from the SPECTRA information-analytical system. It is shown that the high ratio of energies in two regimes is achived due to gas bleaching in the cell.

  8. Does the CO2 laser reduce bond strength in different types of ceramic brackets?

    Directory of Open Access Journals (Sweden)

    Fábio Lourenço Romano

    Full Text Available ABSTRACT OBJECTIVE: The aim of this study was to assess in vitro the influence of the CO2 laser and of the type of ceramic bracket on the shear bond strength (SBS to enamel. METHODS: A total of 60 enamel test surfaces were obtained from bovine incisors and randomly assigned to two groups, according to the ceramic bracket used: Allure (A; Transcend (T. Each group was divided into 2 subgroups (n = 15: L, laser (10W, 3s; C, no laser, or control. Twenty-four hours after the bonding protocol using Transbond XT, SBS was tested at a crosshead speed of 0.5 mm/min in a universal testing machine. After debonding, the Adhesive Remnant Index (ARI was evaluated at 10 x magnification and compared among the groups. Data were analyzed by one-way ANOVA, Tukey’s, Mann-Whitney’s and Kruskal-Wallis tests (α = 0.05. RESULTS: Mean SBS in MPa were: AL = 0.88 ± 0.84; AC = 12.22 ± 3.45; TL = 12.10 ± 5.11; TC = 17.71 ± 6.16. ARI analysis showed that 73% of the specimens presented the entire adhesive remaining on the tooth surfaces (score 3. TC group presented significantly higher SBS than the other groups. The lased specimens showed significantly lower bond strength than the non-lased groups for both tested brackets. CONCLUSION: CO2 laser irradiation decreased SBS values of the polycrystalline ceramic brackets, mainly Allure.

  9. Spectroscopic observation of copper vapor laser

    Science.gov (United States)

    Ueguri, Shigeo; Hara, Kazuhiko; Iwata, Akihiko; Ueda, Yoshihiro; Tabata, Norikazu

    Time-resolved spectrograms of a Cu-vapor laser plasma were obtained. The discharge was generated in Ne or He buffer gas within an Al2O3 ceramic tube. The electrodes were Mo tubes. The observations were made over the wavelength range from 200 to 650 nm. The spectra from the discharge plasma were mainly composed of Cu I and Ne I or He I. Molecular lines, Na D lines, and H Balmer lines were also observed. From the Inglis-Teller formula applied to the observed H Balmer lines, the average electron density was estimated at about 10 to the 14th/cu cm. The time-resolved spectrograms were obtained with a spectrometer and a boxcar averager during several tens of microsecs after the initiation of pulse discharge.

  10. New approach of Co2 laser use in plastic and dermo-cosmetic surgery

    Science.gov (United States)

    Trelles, Mario A.; Trelles, O. R.; Romero, L. F.

    1996-01-01

    Laboratory and mathematical skin examination has played an important role in defining the clinical usefulness and limitations of laser, developing concepts and techniques that have further improved the effectiveness of laser treatment. In addition to this, new technological developments over the years, have helped define the specificity of laser-tissue interaction. Instantaneous conversion by thermal energy of water in a liquid state to a gaseous state when irradiation of skin is done by high power density carbon dioxide laser in short pulses, occurs so quickly that there is minimal thermal conduction to the adjacent tissues structures. The zone of thermal injury could be minimized to the order of only 50 micron thick. In spite of the limited effects of heat conduction, coagulation in vessels can be obtained as well, since small blood vessels are immediately sealed by the laser. Modern carbon dioxide systems can be programmed and make it possible to reproduce shots precisely to vaporize identically thin layers of soft tissue, since absorption by intracellular water limits the depth of penetration. Moreover, collimated handpieces make it possible to deliver a fixed beam diameter and a constant power density as the handpiece is steadily moved over lesions situated on uneven facial contours. The use of large spot sizes gives a more uniform vaporization thus damaging adjacent tissues to a lesser degree, but enlarging of the spot size requires higher energy levels per pulse so that the whole surface can reach a sufficiently high fluence for clean vaporization to take place. For this to be achieved, the fluence required is about 4 - 5 J/cm2 and so UltraPulseR carbon dioxide laser with a 3 mm spot size may be operated with optimal parameters for clean ablation. The resulting surface, covered by dry debris, can be removed by gently scrubbing to avoid thermal build-up, otherwise this remaining tissue can act as a refracting surface as the practical absence of water content

  11. Study of electron kinetics in nitrogen plasma induced by CO2 laser radiation

    Science.gov (United States)

    Nassef, O. Aied; Gamal, Yosr E. E.-D.

    2017-12-01

    In the present work, a numerical modeling is performed to study the electron kinetics in nitrogen plasma induced by CO2 laser radiation operating at wavelength 9.621 μm, and pulse duration of 60 ns corresponding to the measurements carried out by Camacho et al. (J Phys B At Mol Opt Phys 40:4573, 2007). In this experiment, the breakdown threshold intensity is determined for molecular nitrogen over a pressure range 301-760 torr. A previously developed electron cascade model (Evans and Gamal in J Phys D Appl Phys 13:1447, 1980) is modified and applied. This model is based on numerical solution of a time-dependent energy equation and a set of rate equations that describe the time variation of the formed excited states population. The effect of breakdown mechanism is decided through the calculations of the threshold intensity as a function of gas pressure considering the various physical processes that might take place during the interaction. The individual effect of each loss process on the electron energy distribution function and its parameters is studied. This study is performed at the lowest and highest values of the experimentally tested gas pressure range namely; 301 and 760 torr. The obtained results clarified the exact contribution of each loss process to the breakdown of nitrogen induced by CO2 laser radiation.

  12. Study of electron kinetics in nitrogen plasma induced by CO2 laser radiation

    Science.gov (United States)

    Nassef, O. Aied; Gamal, Yosr E. E.-D.

    2017-06-01

    In the present work, a numerical modeling is performed to study the electron kinetics in nitrogen plasma induced by CO2 laser radiation operating at wavelength 9.621 μm, and pulse duration of 60 ns corresponding to the measurements carried out by Camacho et al. (J Phys B At Mol Opt Phys 40:4573, 2007). In this experiment, the breakdown threshold intensity is determined for molecular nitrogen over a pressure range 301-760 torr. A previously developed electron cascade model (Evans and Gamal in J Phys D Appl Phys 13:1447, 1980) is modified and applied. This model is based on numerical solution of a time-dependent energy equation and a set of rate equations that describe the time variation of the formed excited states population. The effect of breakdown mechanism is decided through the calculations of the threshold intensity as a function of gas pressure considering the various physical processes that might take place during the interaction. The individual effect of each loss process on the electron energy distribution function and its parameters is studied. This study is performed at the lowest and highest values of the experimentally tested gas pressure range namely; 301 and 760 torr. The obtained results clarified the exact contribution of each loss process to the breakdown of nitrogen induced by CO2 laser radiation.

  13. Treatment and cosmetic outcome of superpulsed CO2 laser for basal cell carcinoma.

    Science.gov (United States)

    Kavoussi, Hossein; Ebrahimi, Ali

    2013-09-01

    There are many different treatments for basal cell carcinoma, but the most common is surgical excision. CO2 laser could be an alternative treatment for many situations in which other treatments are not possible or available. This follow-up study was performed on 74 (40 female and 34 male) patients with a total of 113 basal cell carcinoma lesions that were pathologically documented. First, the tumor mass was debulked by curettage and later 2 to 5 mm of marginal skin and the debulked area were subjected to 2 to 4 passes of pulsed CO2 laser. Out of 113 lesions, the nodular type accounted for 67 (59.3%) lesions, and 40 (35.4%) lesions were seen in the nasal area as the most common clinical subtype and site of involvement. One hundred six lesions (93.7%) of basal cell carcinoma showed a cure after one session. Good to excellent cosmetic outcomes were seen in 97 (85.8%) cases. This method appears to be an appropriate alternative treatment for basal cell carcinoma lesions that are smaller than 2 cm, superficial, and pigmented, and have a nodular clinical subtype without an aggressive pathologic pattern. This method should be used with caution in the nasal area with lesions larger than 2 cm.

  14. Estudo comparativo entre blefaropeeling e laser fracionado de CO2 no tratamento do rejuvenescimento periorbital

    Directory of Open Access Journals (Sweden)

    Elisangela dos Santos Boeno

    2010-06-01

    Full Text Available Introdução: A queixa de rugas e flacidez na região periocular é freqüente.O blefaropeelingutilizando a fórmula de Baker-Gordon e a aplicação de laser fracionado ablativo de CO2 fracionado são consideradas opções efetivas para o tratamento dessa região. Objetivo: Comparar as técnicas, a recuperação e os resultados finais das duas modalidades terapêuticas. Material e Métodos: Estudo comparativo de hemi-faces em pacientes com dermatocálase e rítides moderadas. Realizou-se no lado direito blefaropeeling e, no esquerdo, laser fracionado de CO2, cujos resultados foram avaliados por fotografia, medidas do sulco palpebral superior e melhora clínica. Resultados: Foram incluídas 11 pacientes no protocolo.Verificou-se melhora clínica efotográfica com ambos os métodos. O tempo de recuperação foi maior com o peeling de fenol. As medidas do sulco palpebral superior não mostraram diferenças significativas. Conclusões: Ambas as modalidades terapêuticas são efetivas no tratamento do envelhecimento periorbital. O processo de recuperação o blefaropeeling foi mais demorado. Clinicamente a melhora da flacidez palpebral foi superior com o blefaropeeling.

  15. Advanced Sine Wave Modulation of Continuous Wave Laser System for Atmospheric CO2 Differential Absorption Measurements

    Science.gov (United States)

    Campbell, Joel F.; Lin, Bing; Nehrir, Amin R.

    2014-01-01

    NASA Langley Research Center in collaboration with ITT Exelis have been experimenting with Continuous Wave (CW) laser absorption spectrometer (LAS) as a means of performing atmospheric CO2 column measurements from space to support the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission.Because range resolving Intensity Modulated (IM) CW lidar techniques presented here rely on matched filter correlations, autocorrelation properties without side lobes or other artifacts are highly desirable since the autocorrelation function is critical for the measurements of lidar return powers, laser path lengths, and CO2 column amounts. In this paper modulation techniques are investigated that improve autocorrelation properties. The modulation techniques investigated in this paper include sine waves modulated by maximum length (ML) sequences in various hardware configurations. A CW lidar system using sine waves modulated by ML pseudo random noise codes is described, which uses a time shifting approach to separate channels and make multiple, simultaneous online/offline differential absorption measurements. Unlike the pure ML sequence, this technique is useful in hardware that is band pass filtered as the IM sine wave carrier shifts the main power band. Both amplitude and Phase Shift Keying (PSK) modulated IM carriers are investigated that exibit perfect autocorrelation properties down to one cycle per code bit. In addition, a method is presented to bandwidth limit the ML sequence based on a Gaussian filter implemented in terms of Jacobi theta functions that does not seriously degrade the resolution or introduce side lobes as a means of reducing aliasing and IM carrier bandwidth.

  16. INTERACTION OF LASER RADIATION WITH MATTER: Influence of a target on operation of a pulsed CO2 laser emitting microsecond pulses

    Science.gov (United States)

    Baranov, V. Yu; Dolgov, V. A.; Malyuta, D. D.; Mezhevov, V. S.; Semak, V. V.

    1987-12-01

    The profile of pulses emitted by a TEA CO2 laser with an unstable resonator changed as a result of interaction of laser radiation with the surface of a metal in the presence of a breakdown plasma. This influence of a target on laser operation and its possible applications in laser processing of materials are analyzed.

  17. Design and optimisation of a pulsed CO2 laser for laser ultrasonics

    CSIR Research Space (South Africa)

    Forbes, A

    2006-02-01

    Full Text Available Laser ultrasonics is the present state-of-the art method for non-destructive testing of composite materials in the aerospace industry. The process is based on an IR laser generating an ultrasound wave that propagates inside the composite material...

  18. Cirurgia de revascularização transmiocárdica a laser de CO2 Transmyocardial laser revascularization surgery using CO2 laser ray

    Directory of Open Access Journals (Sweden)

    Luís Alberto Oliveira DALLAN

    2000-06-01

    Full Text Available Os autores descrevem os princípios de ação dos raios laser, seus diversos tipos e sua interação com os tecidos biológicos. É também relatado o emprego dos raios laser em medicina, desde os estudos experimentais de fotocoagulação em retina de animais, até sua utilização em placas de ateroma e no músculo cardíaco, dando destaque para os trabalhos pioneiros realizados no Brasil. São também descritos os métodos indiretos de revascularização miocárdica, que serviram de base para o emprego dos raios laser na cirurgia de revascularização transmiocárdica, além dos protocolos randomizados que demonstraram ser esse procedimento adequado para o tratamento de um grupo seleto de pacientes. É dado enfoque especial para o tipo de doente selecionado para a revascularização com raios laser, constituído por pacientes na fase final da doença arterial coronária, com miocárdio isquêmico (porém, viável e que ainda apresentam angina, apesar de esgotados todos os recursos habituais de tratamento, especialmente a revascularização miocárdica clássica e a angioplastia. A experiência do Instituto do Coração, num período de dois anos, consiste em 40 pacientes com as características clínicas acima descritas e que foram submetidos à revascularização transmiocárdica com raios laser. Ao final de 12 meses de seguimento, cerca de 87,8% deles obtiveram melhora significativa dos sintomas, com regressão da angina de classes III ou IV, para classes 0, I ou II (pThe authors report the effects of laser rays, the different kinds of rays and their interaction with biological tissues. The use of laser rays in medicine, from photocoagulation experimental studies in the animal retina to their use in atheroma plaques and the cardiac muscle is also reported, with emphasis on the pioneer studies carried out in Brazil. Indirect methods of myocardial revascularization, the basis for the use of laser rays in transmyocardial revascularization

  19. Fabrication of rectangular cross-sectional microchannels on PMMA with a CO2 laser and underwater fabricated copper mask

    Science.gov (United States)

    Prakash, Shashi; Kumar, Subrata

    2017-09-01

    CO2 lasers are commonly used for fabricating polymer based microfluidic devices. Despite several key advantages like low cost, time effectiveness, easy to operate and no requirement of clean room facility, CO2 lasers suffer from few disadvantages like thermal bulging, improper dimensional control, difficulty to produce microchannels of other than Gaussian cross sectional shapes and inclined surface walls. Many microfluidic devices require square or rectangular cross-sections which are difficult to produce using normal CO2 laser procedures. In this work, a thin copper sheet of 40 μm was used as a mask above the PMMA (Polymethyl-methacrylate) substrate while fabricating the microchannels utilizing the raster scanning feature of the CO2 lasers. Microchannels with different width dimensions were fabricated utilizing a CO2 laser in with mask and without-mask conditions. A comparison of both the fabricating process has been made. It was found that microchannels with U shape cross section and rectangular cross-section can efficiently be produced using the with mask technique. In addition to this, this technique can provide perfect dimensional control and better surface quality of the microchannel walls. Such a microchannel fabrication process do not require any post-processing. The fabrication of mask using a nanosecond fiber laser has been discussed in details. An underwater laser fabrication method was adopted to overcome heat related defects in mask preparation. Overall, the technique was found to be easy to adopt and significant improvements were observed in microchannel fabrication.

  20. OmniGuide photonic bandgap fibers for flexible delivery of CO2 laser energy for laryngeal and airway surgery

    Science.gov (United States)

    Torres, David; Weisberg, Ori; Shapira, Gil; Anastassiou, Charalambos; Temelkuran, Burak; Shurgalin, Max; Jacobs, Steven A.; Ahmad, Rokan U.; Wang, Tairan; Kolodny, Uri; Shapshay, Stanley M.; Wang, Zimmern; Devaiah, Anand K.; Upadhyay, Urmen D.; Koufman, Jamie A.

    2005-04-01

    The CO2 laser is the most widely used laser in laryngology, offering very precise cutting, predictable depth of penetration, and minimal collateral damage due to the efficient absorption of CO2 laser by water. Surgical applications of CO2 laser in microlaryngoscopy include removal of benign lesions and early-stage laryngeal cancer. A Transoral Laser Microsurgery (TLM) approach is routinely employed for treatment of laryngeal cancer; however, the role of TLM in advanced malignant lesions remains controversial. The main limiting factor of TLM is the restrictive exposure of the endoscopes combined with the limited cutting ability offered by the existing micromanipulator, enabling cutting only along the straight line-of-sight axis. A flexible fiber delivery system offering a very high quality output beam can offer tangential cutting and can therefore significantly enhance the existing surgical capabilities. Moreover, a flexible fiber for CO2 laser delivery can be used for treatment of benign conditions through flexible endoscopy in an office setting using local anesthesia. OmniGuide Communications Inc. (OGCI) has fabricated a photonic bandgap fiber capable of flexibly guiding CO2 laser energy. Results of laryngeal in-vivo and in-vitro animal studies will be presented. We will discuss the system setup, fiber performance and clinical outcomes. In addition we will present the results of the first human treatment and highlight additional otolaryngology conditions, which will likely benefit from the new technology herein presented.

  1. Laser-based sensor for detection of hazardous gases in the air using waveguide CO2 laser.

    Science.gov (United States)

    Gondal, Mohammed A; Bakhtiari, Imran A; Dastageer, Abdul K

    2007-06-01

    A spectrometer based on the principle of photoacoustic spectroscopy has been developed recently at our laboratory for the detection of hazardous gases such as O3, C2H4, SO2, NO2 and SF6. In most of our earlier works, we employed a mechanical chopper to modulate the laser beam and this chopper modulation has the crucial disadvantage of instability in the chopper frequency. Even a minor shift of about 1 Hz in the modulation frequency could significantly reduce the photoacoustic signal by an order of magnitude at the acoustic resonant mode of the photoacoustic cell. To overcome this problem, we developed a photoacoustic spectrometer where a wave guided CW CO2 laser beam is modulated electronically with the external frequency generator. Our preliminary results show that the electronic modulation of CO2 laser beam improved the sensitivity of our spectrometer by a factor of 6. The parametric dependence of photoacoustic signal on laser power, modulation frequency and trace gas concentration, was investigated and the comparison between the two modulation techniques is presented in this paper for detection of trace gases such as C2H4.

  2. Laser Radiation CO2 Effects in Cement Paste at Different Hydration Stages after Preparation

    Directory of Open Access Journals (Sweden)

    Moreno-Virgen M.R.

    2011-07-01

    Full Text Available In this work the changes occurring in cement pastes irradiated by 10.6µm CO2 laser at diff erent stages of hydration after preparation are presented. Raman spectroscopy, X-ray diffraction and Scanning Electronic Microscopy (SEM techniques were used to observe molecular structural changes. Intensity of cement paste Raman peaks after laser irradiation was monitored in samples irradiated 2, 3, 4, 5, 6, 7, 8, 9, 10 and 11 days after their preparation. Applied laser power changed Raman peaks intensity at 187.5cm-1, 563cm-1, 695cm-1, 750cm-1, 897cm-1, 1042cm-1 and 1159cm-1 that correspond to compounds already present in cement pastes. X-ray diffraction, SEM images and changes in the Raman peaks confirm the recrystalization of cement paste compounds into new phases (alite and belite after irradiation. The produced changes show a clear dependence on the applied laser power density and age of samples.

  3. Plasma column development in the CO2 laser-heated solenoid

    Science.gov (United States)

    Tighe, W.; Offenberger, A. A.; Capjack, C. E.

    1987-08-01

    Axial and radial plasma dynamics in the CO2 laser-heated solenoid have been studied experimentally and numerically. The axial behavior is found to be well described by a self-regulated bleaching wave model. The radial expansion is found to be strongly dependent on the focusing ratio of the input laser beam. With a fast focus ( f/5), the early radial expansion rate is twice that found with a slower focusing arrangement ( f/15). The faster focusing ratio also results in a significantly wider plasma column. On the other hand, no significant dependence of f/♯ on the axial propagation was found. A finite ionization time and the rapid formation of a density minimum on axis are observed and verify earlier experimental results. Detailed comparisons are made with a 2-D magnetohydrodynamic (MHD) and laser propagation code. The axial and radial plasma behavior and, in particular, the dependence of the radial behavior on the focal ratio of the laser are reasonably well supported by the simulation results. Computational results are also in good agreement with experimental measurements of temperature and density using stimulated scattering (Brillouin, Raman) and interferometry diagnostic techniques.

  4. Initiation of long, free-standing z discharges by CO2 laser gas heating

    Science.gov (United States)

    Niemann, C.; Tauschwitz, A.; Penache, D.; Neff, S.; Knobloch, R.; Birkner, R.; Presura, R.; Hoffmann, D. H. H.; Yu, S. S.; Sharp, W. M.

    2002-01-01

    High current discharge channels can neutralize both current and space charge of very intense ion beams. Therefore, they are considered an interesting solution for final focus and beam transport in a heavy ion beam fusion reactor. At the Gesellschaft für Schwerionenforschung accelerator facility, 50 cm long, free-standing discharge channels were created in a 60 cm diameter metallic chamber. Discharges with currents of 45 kA in 2 to 25 mbar ammonia (NH3) gas are initiated by a CO2 laser pulse along the channel axis before the capacitor bank is triggered. Resonant absorption of the laser, tuned to the v2 vibration of the ammonia molecule, causes strong gas heating. Subsequent expansion and rarefaction of the gas prepare the conditions for a stable discharge to fulfill the requirements for ion beam transport. The influence of an electric prepulse on the high current discharge was investigated. This article describes the laser-gas interaction and the discharge initiation mechanism. We found that channels are magnetohydrodynamic stable up to currents of 45 kA, measured by fast shutter and streak imaging techniques. The rarefaction of the laser heated gas is studied by means of a one-dimensional Lagrangian fluid code (CYCLOPS) and is identified as the dominant initiation mechanism of the discharge.

  5. Visualization of transient phenomena during the interaction of pulsed CO2 laser radiation with matter

    Science.gov (United States)

    Schmitt, R.; Hugenschmidt, Manfred

    1996-05-01

    Carbon-dioxide-lasers operating in the pulsed mode with energy densities up to several tens of J/cm2 and peak power densities in the multi-MW/cm2-range may cause fast heating and melting. Eventually quasi-explosive ejection, decomposition or vaporization of material can be observed. Surface plasmas are strongly influencing the energy transfer from the laser radiation field to any target. For optically transparent plastics, such as PMMA for example, only slowly expanding plasmas (LSC-waves) are ignited at fluences around 20 J/cm2, with a low level of self-luminosity. High brightness, supersonically expanding plasma jets (LSD-waves) are generated at the same fluences on glasses. Similar conditions were found for metals as well. From recordings with a high speed CCD-camera, interesting features concerning the initial plasma phases and temporal evolution were deduced. Additionally, information was obtained concerning the quasi explosive ejection of material for PMMA.

  6. Promotional effects of CO2 laser on neoplastic lesions in hamsters

    Science.gov (United States)

    Kingsbury, Jeffrey S.; Margarone, Joseph E., III; Satchidanand, S.; Liebow, Charles

    1991-06-01

    Surgical incision may have promotional effects on neoplastic lesions, possibly through release of tissue growth factors (e.g., EGF, FGF(beta) , IGF, TGF(alpha) ). The CO2 laser may precipitate altered release of these factors. To test this, .5 cm laser, and scalpel incisions were made into fields treated by application of .5% DMBA in acetone, 3 times a week for 6 weeks (group 1) and 12 weeks (group 2). DMBA is a complete carcinogen (initiator and promoter). At 6 weeks, chemically, but not histologically, definable premalignant lesions are seen. Treatment for 12 weeks causes histologic neoplasia which can be graded with T-N-M classification. For both groups, the surgical sites were examined clinically and histologically 4 weeks post-op in a blind fashion. Standard criteria were utilized for defining neoplasia. For group 1, 3 out of 6 laser treated animals developed large exophytic squamous cell carcinomas, but no lesions developed in 12 contralateral, 3 control and 3 scalpel treated pouches. For group 2, 12 of 16 laser treated animals developed tumor with mean grade of 1.75 and mean size of 7.4 mm, 5 of 6 scalpel treated animals developed tumor with mean grade of 1.83 and mean size of 3.6 mm and 3 of 6 control animals developed tumor with mean grade of 1.00 and mean size of 1.5 mm. By the Student 't' test on the binomial distribution lasers cause significant promotion (p < .01). These results suggest that laser surgery may have earlier and more profound promotional effects than scalpel on initiated cells relative to tumor size in the vicinity of the wound site by increased release of growth factors.

  7. Update on Greenlight laser vaporization (PVP) 2014.

    Science.gov (United States)

    Rieken, Malte; Bachmann, Alexander

    2015-04-01

    To asses the (1) outcomes and (2) intraoperative, perioperative, and long-term complications of photoselective vaporization of the prostate (PVP) with Greenlight laser. A systematic review of outcomes and complications of PVP was conducted. The article selection process was performed according to PRISMA guidelines and included publications published between 2009 and 2014. All generations of PVP (80, 120, 180 W) lead to a significant improvement of micturition symptoms (IPSS, QoL) and voiding parameters (Q max, PVR volume) during follow-up. Data on sexual function are heterogeneous and suggest a trend toward decline in erectile function in men with sustained preoperative erection. The rate of intraoperative complications is low. Data on peri- and postoperative complications show a large variation that mainly can be attributed to heterogeneity in documentation. PVP leads to a statistically significant and clinically relevant improvement of voiding parameters and micturition symptoms in patients with prostates technique is characterized by a high degree of intra- and perioperative safety. Long-term evidence on functional outcomes and complications beyond 3 years from RCTs is currently missing for all generations of the Greenlight laser.

  8. Effect of prepulse laser wavelength on EUV emission from CO2 reheated laser-produced Sn plasma

    Science.gov (United States)

    Freeman, J. R.; Harilal, S. S.; Hassanein, A.; Rice, B.

    2013-03-01

    We investigated the role of prepulse laser wavelength on extreme-ultraviolet (EUV) emission and ionic debris generation. A 6 ns Nd:YAG laser operating at 266 nm was used to generate a pre-plasma that was then reheated by a 35 ns CO2 laser pumping pulse at 10.6 μm. At an ideal delay time, improvement in EUV conversion efficiency (CE) of up to 30 % was seen compared to the CE from the pumping pulse alone. It was also shown that the most probable Sn ion kinetic energies were reduced significantly with the use of a prepulse, however, ion fluence increased. These results were compared to those obtained using a 1064 nm prepulse.

  9. Tunable Seed Lasers for Laser Remote Sensing of CO2 and O2 Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Vescent Photonics propose to develop a chip-sized narrow linewidth (< 50 kHz), widely tunable (> 10 nm's) diode laser that will be suitable for a wide variety...

  10. $CO_{2}$ laser ion source Comparison between mode-locked and free- running laser beams

    CERN Document Server

    Lisi, N; Scrivens, R

    2001-01-01

    The production of highly charged ions in a CO/sub 2/ laser-generated plasma is compared for different laser pulse-time structures. The work was performed at the CERN Laser Ion Source, which has the aim of developing a high current, high charge-state ion source for the Large Hadron Collider (LHC). When an intense laser pulse is focused onto a high-Z metal target, the ions expanding in the plasma plume are suitable for extraction from the plasma and matching into a synchrotron. For the first time, a comparison is made between free- running pulses with randomly fluctuating intensity, and mode-locked pulse trains with a reproducible structure and the same energy. Despite the lower power density with respect to the mode-locked pulse train, the free-running pulse provides higher charge states and higher yield. (10 refs).

  11. Laser Prostatectomy: Holmium Laser Enucleation and Photoselective Laser Vaporization of the Prostate

    Science.gov (United States)

    Bostanci, Yakup; Kazzazi, Amir; Djavan, Bob

    2013-01-01

    Historically, transurethral resection of the prostate has been the gold standard for the treatment of benign prostatic hyperplasia (BPH). Laser technology has been used to treat BPH for > 15 years. Over the past decade, it has gained wide acceptance by experienced urologists. This review provides an evidence-based update on laser surgery for BPH with a focus on photoselective laser vaporization and holmium laser enucleation of the prostate surgeries and assesses the safety, efficacy, and durability of these techniques. PMID:23671400

  12. A simple digital control system with field-programmable gate array for stabilization of CO2 laser output

    Science.gov (United States)

    Huang, Renshuai; Guo, Xiaoyang; Meng, Qinglong; Zhang, Bin

    2017-04-01

    A simple digital control system was designed to stabilize CO2 laser based on digital signal processing with the Field-Programmable Gate Array (FPGA) controlling chip and Very-High-Speed Integrated Circuit Hardware Description Language program. In this system, the control parameters were easily determined by software real-time control, and the control circuit was also designed compactly. In addition, the theoretical analysis on the stabilization of CO2 laser output characteristics was presented based on the photoacoustic effect, and the corresponding experiments on the stabilization of CO2 laser output characteristics were further performed. The results show that the output power of CO2 laser is stabilized at the peak with a relative power stability of 2.71%. Furthermore, the frequency of CO2 laser 9P(36) line is stabilized at the center of the laser gain curve with a relative stability of (1.57 ± 0.37)×10-8. This system has a potential of further improvements by optimizing the algorithm and choosing higher-speed signal processor.

  13. A Randomized Controlled Pilot Study on Ablative Fractional CO2 Laser for Consecutive Patients Presenting With Various Scar Types

    NARCIS (Netherlands)

    van Drooge, Anne Margreet; Vrijman, Charlotte; van der Veen, Wietze; Wolkerstorfer, Albert

    2015-01-01

    BACKGROUND Although ablative fractional laser is the gold standard for acne scars, evidence is still lacking for other types of scars. OBJECTIVE To evaluate the efficacy and safety of the ablative fractional 10,600-nm CO2 laser in the treatment of various scar types. MATERIALS AND METHODS The

  14. In Situ analysis of CO2 laser irradiation on controlling progression of erosive lesions on dental enamel.

    Science.gov (United States)

    Lepri, Taísa Penazzo; Scatolin, Renata Siqueira; Colucci, Vivian; De Alexandria, Adílis Kalina; Maia, Lucianne Cople; Turssi, Cecília Pedroso; Corona, Silmara Aparecida Milori

    2014-08-01

    The present study aimed to evaluate in situ the effect of CO2 laser irradiation to control the progression of enamel erosive lesions. Fifty-six slabs of bovine incisors enamel (5 × 3 × 2.5 mm(3) ) were divided in four distinct areas: (1) sound (reference area), (2) initial erosion, (3) treatment (irradiated or nonirradiated with CO2 laser), (4) final erosion (after in situ phase). The initial erosive challenge was performed with 1% citric acid (pH = 2.3), for 5 min, 2×/day, for 2 days. The slabs were divided in two groups according to surface treatment: irradiated with CO2 laser (λ = 10.6 µm; 0.5 W) and nonirradiate. After a 2-day lead-in period, 14 volunteers wore an intraoral palatal appliance containing two slabs (irradiated and nonirradiated), in two intraoral phases of 5 days each. Following a cross-over design during the first intraoral phase, half of the volunteers immersed the appliance in 100 mL of citric acid for 5 min, 3×/day, while other half of the volunteers used deionized water (control). The volunteers were crossed over in the second phase. Enamel wear was determined by an optical 3D profilometer. Three-way ANOVA for repeated measures revealed that there was no significant interaction between erosive challenge and CO2 laser irradiation (P = 0.419). Erosive challenge significantly increased enamel wear (P = 0.001), regardless whether or not CO2 laser irradiation was performed. There was no difference in enamel wear between specimens CO2 -laser irradiated and non-irradiated (P = 0.513). Under intraoral conditions, CO2 laser irradiation did not control the progression of erosive lesions in enamel caused by citric acid. © 2014 Wiley Periodicals, Inc.

  15. CO2 Laser Glazing Treatment of a Veneering Porcelain: Effects on Porosity, Translucency, and Mechanical Properties.

    Science.gov (United States)

    Sgura, R; dos Reis, M C; Salvadori, M C; Hernandes, A C; Cesar, P F; Medeiros, I S

    2015-01-01

    This work tested CO2 laser as a glazing agent and investigated the effects of irradiation on the porosity, translucency, and mechanical properties of veneering porcelain. Sixty discs (diameter 3.5 × 2.0 mm) of veneering porcelain for Y-TZP frameworks (VM9, VITA Zahnfabrik) were sintered and had one of their faces mirror polished. The specimens were divided into six groups (n=10/group) according to surface treatment, as follows: no treatment-control; auto-glaze in furnace following manufacturer's instructions (G); and CO2 laser (45 or 50 W/cm(2)) applied for four or five minutes (L45/4, L45/5, L50/4, L50/5). Optical microscopy (Shimadzu, 100×) was conducted and the images were analyzed with Image J software for the determination of the following porosity parameters: area fraction, average size, and Feret diameter. The translucency parameter studied was masking ability, determined by color difference (ΔE) over black and white backgrounds (CM3370d, Konica Minolta). Microhardness and fracture toughness (indentation fracture) were measured with a Vickers indenter (HMV, Shimadzu). Contact atomic force microscopy (AFM) (50 × 50 μm(2), Nanoscope IIIA, Veeco) was performed at the center of one sample from each group, except in the case of L45/5. With regard to porosity and translucency parameters, auto-glazed and laser-irradiated specimens presented statistical similarity. The area fraction of the surface pores ranged between 2.4% and 5.4% for irradiated specimens. Group L50/5 presented higher microhardness when compared to the G group. The higher (1.1) and lower (0.8) values for fracture toughness (MPa.m(1/2)) were found in laser-irradiated groups (L50/4 and L45/4, respectively). AFM performed after laser treatment revealed changes in porcelain surface profile at a submicrometric scale, with the presence of elongated peaks and deep valleys.

  16. Wavelength dependence of prepulse laser beams on EUV emission from CO2 reheated Sn plasma

    Science.gov (United States)

    Freeman, J. R.; Harilal, S. S.; Sizyuk, T.; Hassanein, A.; Rice, B.

    2012-03-01

    Extreme ultraviolet (EUV) emission from laser-produced plasmas (LPP) centered at 13.5 nm is considered a leading candidate for the light source in future lithography systems. Tin is currently the best material for generating this EUV emission since it emits strongly within the 13.5 nm region due to its various ionic states (Sn8+-Sn14+). Highly efficient and low-debris LPPs are a pre-requisite for their use as light sources for EUV lithography. Tin plasmas generate debris that can damage collection optics over time. Techniques to mitigate debris are needed to extend the lifetime of these components and the system. Optimization of plasma conditions is necessary for increasing EUV emission and enhancing conversion efficiency (CE). Improving the source CE is necessary in order to reduce the cost of ownership and hence, develop a commercially viable lithography system for the semiconductor industry. One method to accomplish this is to reheat pre-formed plasma with a laser pulse to enhance EUV emission. This enhancement is achieved by controlling those plasma conditions necessary for optimizing EUV emission. We investigated the role of prepulse laser wavelength on prepulse plume formation and EUV in-band signal enhancement. A 6 ns Nd:YAG laser operating at 1064 nm and 266 nm was used for generating the prepulse plume. The expanding plume was then reheated by a 35 ns CO2 laser operating at 10.6 μm. The role of prepulse wavelength and energy on EUV conversion efficiency is discussed.

  17. Optimization of CO2 laser cutting parameters on Austenitic type Stainless steel sheet

    Science.gov (United States)

    Parthiban, A.; Sathish, S.; Chandrasekaran, M.; Ravikumar, R.

    2017-03-01

    Thin AISI 316L stainless steel sheet widely used in sheet metal processing industries for specific applications. CO2 laser cutting is one of the most popular sheet metal cutting processes for cutting of sheets in different profile. In present work various cutting parameters such as laser power (2000 watts-4000 watts), cutting speed (3500mm/min - 5500 mm/min) and assist gas pressure (0.7 Mpa-0.9Mpa) for cutting of AISI 316L 2mm thickness stainless sheet. This experimentation was conducted based on Box-Behenken design. The aim of this work is to develop a mathematical model kerf width for straight and curved profile through response surface methodology. The developed mathematical models for straight and curved profile have been compared. The Quadratic models have the best agreement with experimental data, and also the shape of the profile a substantial role in achieving to minimize the kerf width. Finally the numerical optimization technique has been used to find out best optimum laser cutting parameter for both straight and curved profile cut.

  18. Treatment of tooth fracture by medium energy CO2 laser and DP-bioactive glass paste: thermal behavior and phase transformation of human tooth enamel and dentin after irradiation by CO2 laser.

    Science.gov (United States)

    Lin, C P; Lee, B S; Kok, S H; Lan, W H; Tseng, Y C; Lin, F H

    2000-06-01

    Acute trauma or trauma associated with occlusal disharmony can produce tooth crack or fracture. Although several methods are proposed to treat the defect, however, the prognosis is generally poor. If the fusion of a tooth fracture by laser is possible it will offer an alternative to extraction or at least serve as an adjunctive treatment in the reconstruction. The responses of soft tissues to lasers of different wavelengths are fairly well known, but the reactions of hard tissues are still to be understood. The purpose of this research was to study the feasibility of using a medium energy continuous-wave CO(2) laser and a low melting-point bioactive glass to fuse or bridge tooth fractures. The present report is focused on the first part of the research, the analysis of changes in laser-irradiated human tooth enamel/dentin by means of X-ray diffractometer (XRD), Fourier-transforming infrared spectroscopy (FTIR), differential thermal analysis/thermogravimetric analysis (DTA/TGA), and scanning electron microscopy (SEM). After CO(2) laser irradiation, there were no marked changes in the X-ray diffraction pattern of the enamel when compared to that before laser treatment. However, a small peak belonging to alpha-TCP appeared at the position of 2theta=30.78 degrees C. After being treated with CO(2) laser, the dentin showed much sharper peaks on the diffraction patterns because of grain growth and better crystallinity. alpha-TCP and beta-TCP were identified after laser treatment. In the FTIR analysis, an HPO(4)(-2) absorption band was noted before laser treatment disappeared after the irradiation. No significant change in the absorption band of HPO(4)(-2) was found on the FTIR curves of enamel after laser treatment. The results of DTA/TGA indicated that loss of water and organic materials occurred in both enamel and dentin after laser treatment. Under SEM, melting and resolidification occurred in both enamel and dentin by medium energy of CO(2) laser. This implies that

  19. Experimental comparison of laser energy losses in high-quality laser-oxygen cutting of low-carbon steel using radiation from fibre and CO2 lasers

    Science.gov (United States)

    Golyshev, A. A.; Malikov, A. G.; Orishich, A. M.; Shulyat'ev, V. B.

    2015-09-01

    We report a comparative experimental study of laseroxygen cutting of low-carbon steel using a fibre laser with a wavelength of 1.07 μm and a CO2 laser with a wavelength of 10.6 μm at the sheet thickness of 3 - 16 mm. For the two lasers we have measured the dependence of the cutting speed on the radiation power and determined the cutting speed at which the surface roughness is minimal. The coefficient of laser radiation absorption in the laser cutting process is measured for these lasers at different values of the cutting speed and radiation power. It is found that the minimal roughness of the cut surface is reached at the absorbed laser energy per unit volume of the removed material, equal to 11 - 13 J mm-3; this value is the same for the two lasers and does not depend on the sheet thickness.

  20. Nickel Nanoparticles Production using Pulsed Laser Ablation under Pressurized CO2

    Science.gov (United States)

    Mardis, Mardiansyah; Takada, Noriharu; Machmudah, Siti; Diono, Wahyu; Kanda, Hideki; Sasaki, Koichi; Goto, Motonobu

    2014-10-01

    We used nickel (Ni) plate as a target and irradiated pulse laser ablation with a fundamental wavelength of 1064 nm under pressurized CO2. The Ni plate was ablated at various pressure (5-15 MPa), temperature (15-80°), and irradiation time (3-30 min). The method successfully generated Ni nanoparticles in various shape and size. Generated Ni nanoparticles collected on a Si wafer and the ablated Ni plate were analyzed by Field Emission Scanning Electron Microscope (FE-SEM). With changing pressure and temperature, the structures of Ni nanoparticles also changed. The shape of generated particles is sphere-like structure with diameter around 10--100 nm. Also it was observed that a network structure of smaller particles was fabricated. The mechanism of nanoparticles fabrication could be explained as follows. Ablated nickel plate melted during the ablation process and larger particles formed, then ejected smaller spherical nanoparticles, which formed nanoclusters attached on the large particles. This morphology of particles was also observed for gold and silver nanoparticles with same condition. Further, the optical emission intensity from ablation plasma and the volume of the ablated crater were also examined under pressurized CO2.

  1. Microstructure and Mechanical Properties of Hybrid Welded Joints with Laser and CO2-Shielded Arc

    Science.gov (United States)

    Wahba, M.; Mizutani, M.; Katayama, S.

    2016-07-01

    With the objective of reducing the operating costs, argon-rich shielding gas was replaced by 100% CO2 gas in hybrid laser-arc welding of shipbuilding steel. The welding parameters were optimized to obtain buried-arc transfer in order to mitigate spatter formation. Sound butt joints could be successfully produced for plates of 14 and 17 mm thickness in one welding pass. Subsequently, the welded joints were subjected to different tests to evaluate the influence of CO2 shielding gas on the mechanical properties of the welded joints. All tensile-tested specimens failed in the base material, indicating the higher strength of the welded joints. The impact toughness of the welded joints, measured at -20 °C, reached approximately 76% of that of the base material, which was well above the limit set by the relevant standard. The microstructure of the fusion zone consisted of grain boundary ferrite and acicular ferrite uniformly over the plate thickness except for the joint root where the microstructure was chiefly ferrite with an aligned second phase. This resulted in higher hardness in the root region compared with the top and middle parts of the fusion zone.

  2. Food powder analysis by using transversely excited atmospheric CO2 laser-induced plasma spectroscopy

    Science.gov (United States)

    Khumaeni, Ali; Sukra Lie, Zener; Setiabudi, Wahyu; Hendrik Kurniawan, Koo; Kagawa, Kiichiro

    2015-06-01

    A direct and sensitive analysis of food powder sample has successfully been carried out by utilizing the special characteristics of pulsed transversely excited atmospheric (TEA) CO2 laser. In this study, a food powder was placed in a container made of copper plate and covered by a metal mesh. The container was perpendicularly attached on a metal surface. A high-temperature luminous plasma was induced on a metal surface 5 mm above the mesh. Once the plasma was produced, a strong shock wave was induced, blowing-off of the powder from the container to enter into the plasma to be dissociated and excited. By using this method, a semi-quantitative analysis of food powder was made. The detection limits of Cr in the powdered agar and Cd in the powdered rice were 9 mg/kg and 50 mg/kg, respectively.

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

    Directory of Open Access Journals (Sweden)

    Javad Sarabadani

    2017-09-01

    Full Text Available 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.

  4. Carbon cloth damage induced by various shapes of CO2 laser pulses

    Science.gov (United States)

    Kaludjerović, B.; Trtica, M.; Babić, B.; Radak, B.; Ionin, A.

    2008-04-01

    A qualitative study of the damages on a carbon cloth induced by various shapes of CO2 laser pulses is presented. Three pulse shapes were used: short (100 ns, 84 MW/cm2), tailed (˜100-ns spike of 70 MW/cm2, 2-μs tail), and extralong (45 μs, 0.5 MW/cm2). Apparently, the energy absorbed by the cloth was mainly converted into thermal energy, causing a range of damages, from instantaneous evaporation to cracking and melting, all of which resulted in the cutting of individual fibers in the yarns of the cloth. The two longer types of pulses allowed sufficient time for the stabilization of the affected zone temperature, thus producing melting and a crater-like “burning through” of the cloth.

  5. Estudo comparativo entre blefaropeeling e laser fracionado de CO2 no tratamento do rejuvenescimento periorbital

    OpenAIRE

    Elisangela dos Santos Boeno; Thiago Vinícius Ribeiro Cunha; André César Antiori Freire Pessanha; Tatiana Aline Steiner; Fernanda Ayres de Morais e Silva; Denise Steiner

    2010-01-01

    Introdução: A queixa de rugas e flacidez na região periocular é freqüente.O blefaropeelingutilizando a fórmula de Baker-Gordon e a aplicação de laser fracionado ablativo de CO2 fracionado são consideradas opções efetivas para o tratamento dessa região. Objetivo: Comparar as técnicas, a recuperação e os resultados finais das duas modalidades terapêuticas. Material e Métodos: Estudo comparativo de hemi-faces em pacientes com dermatocálase e rítides moderadas. Realizou-se no lado direito blefaro...

  6. HOS cell adhesion on Ti6Al4V ELI texturized by CO2 laser

    Science.gov (United States)

    Sandoval-Amador, A.; Bayona–Alvarez, Y. M.; Carreño Garcia, H.; Escobar-Rivero, P.; Y Peña-Ballesteros, D.

    2017-12-01

    In this work, the response of HOS cells on Ti6Al4V ELI textured surfaces by a CO2 laser was evaluated. The test surfaces were; smooth Ti6Al4V, used as the control, and four textured surfaces with linear geometry. These four surfaces had different separation distances between textured lines, D1 (1000 microns), D2 (750 microns), D3 (500 microns) and D4 (250 microns). Toxicity of textured surfaces was assessed by MTT and the cellular adhesion test was performed using HOS ATCC CRL 1543 line cells. This test was done after 5 days of culture in a RPMI 1640 medium supplemented with 10% fetal bovine serum and 1% antibiotics. The results showed that the linear textures present 23% toxicity after 30 days of incubation, nevertheless, the adhesion tests results are inconclusive in such conditions and therefore the effect of the line separation on the cell adhesion cannot be determined.

  7. Design and optimisation of a pulsed CO2 laser for laser ultrasonic applications

    CSIR Research Space (South Africa)

    Forbes, A

    2006-07-01

    Full Text Available at the material surface is detected and converted into a defect map across the aircraft. The design and optimization of a laser system for this application, together with the basic science involved, is reviewed in this paper. This includes the optimization...

  8. Low-fluence CO2 laser irradiation: selective epidermal damage to human skin.

    Science.gov (United States)

    Kamat, B R; Tang, S V; Arndt, K A; Stern, R S; Noe, J M; Rosen, S

    1985-09-01

    The interaction of normal human skin with low-fluence CO2 laser irradiation was studied using a three-phase approach. In phase one, freshly excised skin was observed immediately after impact. In phase two, skin irradiated 2 h prior to excision was studied. In phase three, human volunteers were irradiated and biopsied at time zero, 24 h and 48 h. Seventy-five sites were exposed and 60 biopsies were performed. The earliest histologic changes were observed in the 6-10 J/cm2 fluence (radiant exposure) range and these changes included spindle and vacuolar changes in the basal layer of the epidermis. Papillary dermal coagulation was present to a maximum of 0.03 mm. At fluences of 10-25 J/cm2, superficial dermal necrosis (0.06-0.08 mm) was observed. At fluences above 25 J/cm2, transepidermal necrosis was present with increasing papillary dermal necrosis that was in proportion to the energy density delivered. At 2h, basal vacuolar changes were accompanied by diffuse keratinocytic cell death where contact was maintained between the epidermis and dermis, while where separation occurred limited keratinocytic death was observed. The earliest changes occurred at lower threshold fluences (4-6 J/cm2). After 24 h, these doses resulted in extensive epidermal necrosis with focal acute inflammatory infiltrates. At 48 h, the degree of epidermal "slough" was proportional to the energy density delivered and was maximal with a fluence of 5.7 J/cm2 delivered whereas with a fluence of 3.8 J/cm2 thin slough (0.02 mm) was observed. These findings suggest that low-dose CO2 laser irradiation may provide a new approach to selectively damage the epidermis with minimal dermal damage.

  9. Prospective evaluation of CO2 laser-assisted sclerectomy surgery (CLASS) with Mitomycin C.

    Science.gov (United States)

    Cutolo, Carlo Alberto; Bagnis, Alessandro; Scotto, Riccardo; Bonzano, Chiara; Traverso, Carlo Enrico

    2018-01-01

    Our purpose was to evaluate the clinical safety and efficacy of CO2 laser-assisted sclerectomy surgery (CLASS) with Mitomycin C (MMC) in open angle glaucoma (OAG). This was a prospective, uncontrolled, interventional case series. All subjects underwent CLASS procedure by a single surgeon. After the dissection of a partial thickness scleral flap, topical MMC 0.2 mg/ml was applied to the sclera and the conjunctiva for 3 min. The CO2 laser with a beam-manipulating system was used to ablate the scleral tissue and expose the Schlemm's canal area. Primary outcomes: intraocular pressure (IOP) change, number of IOP-lowering medicaments change. Adverse events were evaluated as secondary outcomes. Twenty-one eyes of 21 patients underwent the CLASS procedure. Thirteen were primary OAG (62%), two normal pressure glaucoma (10%), three exfoliative glaucoma (14%) and three others secondary OAG. With a mean (SD) follow-up of 15.3 (5.9) months, the IOP changed from 25.4 (6.7) mmHg at baseline to 10.9 (3.4) mmHg al the last visit. Mean reduction of IOP was -14.5 mmHg (95% CI, -17.7 to -11.2, P maculopathy successfully treated with placement of additional transconjunctival scleral flap sutures. The CLASS procedure with MMC is clinically safe and effective maintaining a large reduction in IOP and in the number of IOP-lowering medications with a mean follow-up of 15 months. Iris adhesion at the filtrating area warrants further evaluation and possibly reflects the surgeon's learning curve.

  10. Resonant excitation of ethylene molecules in the combustion flame CVD of diamond using a wavelength tunable CO2 laser

    Science.gov (United States)

    Xie, Z. Q.; Park, J. B.; He, X. N.; Gao, Y.; Zhou, Y. S.; Lu, Y. F.

    2010-02-01

    CO2 laser resonant excitations of precursor molecules were applied in combustion flame synthesis of diamond films. The combustion flame was produced from a mixture of ethylene (C2H4), acetylene (C2H2) and oxygen (O2). A wavelength-tunable CO2 laser with wavelength range from 9.2 to 10.9 μm was used for wavelength-matched excitation of the ethylene molecules. By irradiating the flame using CO2 laser at 10.532 μm, the ethylene molecules were resonantly excited through the CH2 wagging vibrational mode (ν7, 949.3 cm-1). Irradiation of the flame using the common CO2 laser wavelength at 10.591 μm was also carried out for comparison. It was found that diamond synthesis was more obviously enhanced by the CO2 laser resonant excitation at 10.532 μm as compared to that at 10.591 μm. Firstly, the flame was shortened by 50%, indicating a promoted reaction in the process. Secondly, the diamond grain sizes as well as the diamond film thicknesses were increased by 200~300% and 160% respectively, indicating a higher growth rate of diamond films. Finally, Raman spectra of the diamond sample showed a sharp diamond peak at 1334 cm-1 and a suppressed G-band, indicating higher diamond quality.

  11. Fractional CO(2) laser treatment vs autologous fat transfer in the treatment of acne scars: a comparative study.

    Science.gov (United States)

    Azzam, Omar A; Atta, Ahmed T; Sobhi, Rehab M; Mostafa, Pakinam I N

    2013-01-01

    Acne scars present a highly challenging and frustrating clinical problem. Fractional CO2 laser treatment has led to marked improvement in scars, and fat transfer, or fat grafting, has also recently proven very useful in regenerative medicine. To compare fractional CO2 laser treatment and fat grafting in the treatment of acne scars. Twenty patients were included in this study, 10 received 3 sessions of fractional CO2 laser therapy, and 10 received fat grafting. All patients were then followed up for 3 months, and results were assessed with digital photographs taken by a committee of 3 physicians, by a single-blinded physician, and by reports of patient satisfaction. In the fractional CO2 laser treatment group, under 20% of patients were graded as having excellent scar improvement, 0 as having marked scar improvement, under 10% as having mild scar improvement, and almost 70% as having moderate scar improvement. In the fat-grafting group, the scar and overall improvement were graded as 30% excellent, 30% marked, 20% moderate, and 20% mild. Fat grafting proved to be more effective in the treatment of acne scars than ablative fractional CO2 laser treatment. There were many points in its favor, the most significant being the clinical improvement in scars and texture. This supports the stem cell theory of adipose tissue in regenerative medicine.

  12. Various effects of the CO2-, the neodymium-YAG-, and the argon-laser irradiation on bladder tissue.

    Science.gov (United States)

    Frank, F; Keiditsch, E; Hofstetter, A; Pensel, J; Rothenberger, K

    1982-01-01

    Application of lasers as cutting or coagulation instruments is based on the conversion of light energy into heat in the irradiated tissue. The extent and degree of the thermal action depends on the beam geometry and the energy of the incident light, as well as on the optic and thermal properties of this tissue. The extinction behavior in the tissue differs for the various laser systems employed in medicine. A comparison of the effects on bladder tissue of rats and rabbits is made with Neodymium-YAG laser and the argon and CO2 lasers to demonstrate the advantages of the Neodymium-YAG laser, especially for the therapeutic irradiation of bladder tumors.

  13. The synergistic effects of CO2 laser treatment with calcium silicate cement of antibacterial, osteogenesis and cementogenesis efficacy

    Science.gov (United States)

    Hsu, T.-T.; Kao, C.-T.; Chen, Y.-W.; Huang, T.-H.; Yang, J.-J.; Shie, M.-Y.

    2015-05-01

    Calcium silicate-based material (CS) has been successfully used in dental clinical applications. Some researches show that the antibacterial effects of CO2 laser irradiation are highly efficient when bacteria are embedded in biofilm, due to a photo-thermal mechanism. The purpose of this study was to confirm the effects of CO2 laser irradiation on CS, with regard to both material characterization and human periodontal ligament cell (hPDLs) viability. CS was irradiated with a dental CO2 laser using directly mounted fiber optics in wound healing mode with a spot area of 0.25 cm2, and then stored in an incubator at 100% relative humidity and 37 °C for 1 d to set. The hPDLs cultured on CS were analyzed, along with their proliferation and odontogenic differentiation behaviors. The results indicate that the CO2 laser irradiation increased the amount of Ca and Si ions released from the CS, and regulated cell behavior. CO2 laser-irradiated CS promoted cementogenic differentiation of hPDLs, with the increased formation of mineralized nodules on the substrate’s surface. It also up-regulated the protein expression of multiple markers of cementogenic and the expression of cementum attachment protein. The current study provides new and important data about the effects of CO2 laser irradiation on CS. Taking cell functions into account, the Si concentration released from CS with laser irradiated may be lower than a critical value, and this information could lead to the development of new regenerative therapies for dentin and periodontal tissue.

  14. Thermal behaviors of stainless steel tube based GeO2 ATR hollow fibers for transmitting CO2 laser radiations

    Science.gov (United States)

    Wang, Xu; Wang, Lin; Fu, Xiaohong; Jing, Chengbin; Yue, Fangyu; Yang, Pingxiong; Chu, Junhao

    2017-10-01

    The stainless steel (SUS) capillary tube attenuated total reflective (ATR) GeO2 hollow waveguide has advantages of low fabrication cost, strong mechanic strength and low transmission loss. It can find laser power delivery applications such as laser surgery, and material processing. However, the temperature rise of the operating waveguide may affect the laser delivery stability and the laser surgery safety. The thermal behaviors of the SUS ATR hollow fiber transmitting CO2 laser were investigated theoretically and experimentally in this work. Both theoretic simulations and experimental results disclose the periodic oscillatory behavior of the fiber temperature. The influence of input laser power on fiber temperature has been quantitatively discussed. A maximum input laser power of 23 W is predicted for laser surgery in which case the fiber temperature had better be lower than 47 °C to avoid tissue scalds. An input laser power smaller than 137 W is suggested preventing the fiber from being overheated (150 °C).

  15. Preliminary investigation into laser high voltage interaction in the case of streamer-to-leader process using a high power CO 2 laser

    CSIR Research Space (South Africa)

    West, NJ

    2006-01-01

    Full Text Available This paper describes the preliminary small-scale experiments conducted in order to investigate the influence of intensely focused laser light produced by a CO 2 laser on high voltage fields. The laser used operated at a maximum energy of 430 mJ per...

  16. Vaporization reduction characteristics of aqueous ammonia solutions by the addition of ethylene glycol, glycerol and glycine to the CO2 absorption process.

    Science.gov (United States)

    Seo, Jong-Beom; Jeon, Soo-Bin; Kim, Je-Young; Lee, Gang-Woo; Jung, Jong-Hyeon; Oh, Kwang-Joong

    2012-01-01

    Aqueous ammonia (NH3) solution can be used as an alternative absorption for the control of CO2 emitted from flue gases due to its high absorption capacity, fast absorption rate and low corrosion problem. The emission of CO2 from iron and steel plants requires much attention, as they are higher than those emitted from power plants at a single point source. In the present work, low concentration ammonia liquor, 9 wt.%, was used with various additives to obtain the kinetic properties using the blast furnace gas model. Although a solution with a high ammonia concentration enables high CO2 absorption efficiency, ammonium ions are lost as ammonia vapor, resulting in reduced CO2 absorption due to the lower concentration of the ammonia absorbent. To decrease the vaporization of ammonia, ethylene glycol, glycerol and glycine, which contain more than one hydroxyl radical, were chosen. The experiments were conducted at 313 K similar to the CO2 absorption conditions for the blast furnace gas model.

  17. Tratamiento del rinofima con láser de CO2: Presentación de un caso Treatment of rhinophyma with CO2 laser: A case report

    Directory of Open Access Journals (Sweden)

    J.L. Cebrián Carretero

    2006-04-01

    Full Text Available Introducción. El rinofima es una alteración cutánea de la región nasal que produce problemas estéticos importantes. Describimos nuestra experiencia en un caso de rinofima avanzado y su resolución por medio de una técnica sencilla. Material y métodos. Previa desinfección cutánea se realizó anestesia infiltrativa y bloqueo troncular de nervios infraorbitarios y etmoidales. A continuación se realizó la resección de casi todo el espesor cutáneo con un láser de CO2 Lumenis Sharplan conservando la dermis profunda para permitir la curación por segunda intención. Posteriormente se aplicó vaselina y se realizaron curas y lavados diarios. El paciente fue dado de alta al día siguiente de la intervención. Resultados. Los resultados estéticos fueron muy buenos. El dolor postoperatorio fue controlado con analgesia habitual. En la primera semana se objetivaba un buen grado de cicatrización. A los 2 meses la reepitelización fue completa y ya no se observaban costras ni eritema. Conclusión. La utilización del láser de CO2 en el tratamiento del rinofima avanzado logra unos excelentes resultados estéticos con una morbilidad y riesgo operatorio mínimos.Introduction. Rhinophyma is a skin alteration of the nasal region that causes considerable aesthetic problems. We describe our experience with a case of advanced rhinophyma and its resolution by means of a simple technique. Materials and methods. The skin area was disinfected beforehand, anaesthesia infiltration and the infraorbital and ethmoidal nerve trunks were blocked. Then, using a Lumenis Sharplan CO2 laser almost the complete skin thickness was resected while preserving the deep dermis layer so as to allow second intention healing. Later, Vaseline was applied and the area was treated daily. The patient was discharged the day after the intervention. Results. The aesthetic results were very good. Postoperative pain was controlled with standard analgesics. Adequate healing was

  18. 5-Aminolevulinic Acid Photodynamic Therapy combined with CO2 laser therapy in treatment of laryngeal papilloma: Case report.

    Science.gov (United States)

    Zhang, Yunjie; Yang, Yuguang; Zou, Xianbiao; Huang, Zheng

    2016-06-01

    This article describes the case of 5-Aminolevulinic Acid Photodynamic Therapy (ALA-PDT) via self-retaining laryngoscope under general anesthesia combined with CO2 Laser Therapy in the treatment of three patients with juvenile laryngeal papilloma. Laryngeal papilloma Clinically, it features rapid growth, multi-focus, frequent recurrence and possibility of spreading to the lower respiratory tract. ALA-PDT via self-retaining laryngoscope under general anesthesia combined with CO2 Laser Therapy is safe and effective for clearing laryngeal papilloma, laryngeal papilloma was fully removed from the three patients, with no recurrence during the 6-24 months of follow-up medical examination. 5-Aminolevulinic Acid Photodynamic Therapy (ALA-PDT) via self-retaining laryngoscope under general anesthesia combined with CO2 Laser can be used for treating laryngeal papilloma. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Single Session Treatment of Rolling Acne Scars Using Tumescent Anesthesia, 20% Trichloracetic Acid Extensive Subcision, and Fractional CO2 Laser.

    Science.gov (United States)

    Taylor, Mark B; Zaleski-Larsen, Lisa; McGraw, Timothy A

    2017-01-01

    Successful treatment of acne scars is challenging. Many modalities have been used with marginal success. The authors describe a combination of a superficial chemical peel, subcision, and fractional carbon dioxide (CO2) laser resurfacing in a single-treatment session as a novel treatment approach for rolling acne scars. A total of 114 patients (75 women and 39 men) with predominantly rolling acne scars were treated with a 20% trichloracetic acid chemical peel, subcision with a novel dissecting instrument, and the CO2 laser under tumescent anesthesia. This was a retrospective, uncontrolled, unblinded study. The mean improvement after a single treatment was 2.9 on a scale of 1 to 4 with few complications. Ninety percent of the patients were satisfied with their final result and desired no additional treatment. The combination of a trichloracetic acid 20% chemical peel, subcision, and fractional CO2 laser resurfacing combined with tumescent anesthesia is both safe and effective in the treatment of rolling acne scars.

  20. Treatment results of CO2 laser vaporisation in a cohort of 35 patients with oral leukoplakia.

    Science.gov (United States)

    Brouns, E R E A; Baart, J A; Karagozoglu, K H; Aartman, I H A; Bloemena, E; van der Waal, I

    2013-03-01

    The aim of the present study was to evaluate the treatment results of CO2 laser vaporisation in a well-defined cohort of patients with oral leukoplakia (OL). The group consisted of 35 patients. Before treatment, a clinical photograph and an incisional biopsy were performed in all cases. Also posttreatment results were documented with clinical photographs. The assessment of the treatment results was performed by an independent clinician who had not performed the treatment. The mean follow-up period was 61.9 months (range 12-179 months). In 14/35 patients, there was a recurrence between 1 and 43 months (mean 18.7 months), the annual recurrence rate being approximately 8%. In three of these patients, malignant transformation occurred at a later stage. In two other patients, a malignancy occurred without a prior recurrence. In altogether 5 of 35 patients, malignant transformation occurred in a mean period of 54 months, the annual malignant transformation rate being approximately 3%. The results in the present study are worse than those reported in the literature, perhaps owing to the use of different diagnostic criteria for OL, differences in the employed laser technique and assessment of possible recurrences by an independent clinician. © 2012 John Wiley & Sons A/S.

  1. Interaction of CO2 laser pulses with solid targets in magnetic fields

    Science.gov (United States)

    Loter, N. G.; Halverson, W.; Lax, B.

    1981-08-01

    High-temperature plasmas were generated by focussing 225-J gain-switched CO2 laser pulses onto planar solid targets within the bore of a Bitter solenoid magnet. DC magnetic fields up to 100 kG were applied parallel to the laser propagation vector, partially confining a long plasma column streaming away from the target. Target materials included teflon (CF2), graphite, and Al. Soft x-ray diagnostics, including a dual-channel, time-resolving TAP crystal spectrometer, a pinhole camera, and differentially-filtered p-i-n diodes, were used to determine electron density, electron temperature, and axial and radial expansion characteristics of the plasma. From these measurements, it was deduced that effects of refraction became increasingly important as B was increased; furthermore, these effects were strongly dependent on target material. For all targets, refraction occurred late in the pulse when the radially confined plasmas left the focal volume. For teflon and aluminum targets, but not for the lower Z graphite targets, it was inferred that significant side scattering also occurred early in the pulse with sufficiently strong magnetic fields.

  2. Corrosion of Ti6Al4V ELI surfaces texturized by CO2 laser in SBF

    Science.gov (United States)

    Sandoval-Amador, A.; Daza Rodriguez, J. J.; Montañez Supelano, N. D.; Sanabria Cala, J. A.; Y Peña-Ballesteros, D.

    2017-12-01

    The purpose of our study was to evaluate the corrosion behavior of Ti6Al4V ELI surfaces textured with linear geometry using a CO2 laser. The linear geometry of the textures was obtained using a laserpro X380RX device with a 40W power supply. The characterization of the textured surface was performed by scanning electron microscope and X-ray dispersive energy spectroscopy. The effect of the separation distance of the linear textures on the corrosion resistance of the Ti6Al4V ELI alloy was evaluated by resistance to linear polarization, electrochemical impedance spectroscopy and potentiodynamic polarization curves in SBF. The results showed that the separation distance of the linear textures does not generate a significant effect on the corrosion resistance of the material. However, all the textured surfaces presented less resistance to corrosion than the unmodified material. This decrease in the corrosion resistance is attributed to the inclusion of elements such as molybdenum, silicon and phosphorus that are present in the lines due to the implementation of the cermark coating prior to the laser textured process.

  3. Er:YAG, CO, and CO(2) laser delivery by ZnS-coated Ag hollow waveguides.

    Science.gov (United States)

    Matsuura, Y; Miyagi, M

    1993-11-20

    ZnS-coated Ag hollow waveguides for Er:YAG, CO, and CO(2) laser light are fabricated based on a sputtering and an electroplating technique. Three types of these waveguides with a 1-mm diameter and a 1-m length are fabricated. Two of them are designed to achieve the minimum loss at the wavelengths of Er:YAG and CO laser light, and the other is for all the lasers. Straight losses of 0.4, 0.5, and 0.25 dB/m are obtained for Er:YAG, CO, and CO(2) laser light, respectively. Because the waveguides are flexible and low loss, they are useful in delivery of mid-infrared lasers in industrial and medical applications.

  4. Effects of early combinatorial treatment of autologous split-thickness skin grafts in red duroc pig model using pulsed dye laser and fractional CO2 laser.

    Science.gov (United States)

    Bailey, J Kevin; Blackstone, Britani N; DeBruler, Danielle M; Kim, Jayne Y; Baumann, Molly E; McFarland, Kevin L; Imeokparia, Folasade O; Supp, Dorothy M; Powell, Heather M

    2017-07-31

    The use of pulsed dye laser (PDL) and fractional CO2 (FX CO2 ) laser therapy to treat and/or prevent scarring following burn injury is becoming more widespread with a number of studies reporting reduction in scar erythema and pruritus following treatment with lasers. While the majority of studies report positive outcomes following PDL or FX CO2 therapy, a number of studies have reported no benefit or worsening of the scar following treatment. The objective of this study was to directly compare the efficacy of PDL, FX CO2 , and PDL + FX CO2 laser therapy in reducing scarring post burn injury and autografting in a standardized animal model. Eight female red Duroc pigs (FRDP) received 4 standardized, 1 in. x 1 in. third degree burns that were excised and autografted. Wound sites were treated with PDL, FX CO2 , or both at 4, 8, and 12 weeks post grafting. Grafts receiving no laser therapy served as controls. Scar appearance, morphology, size, and erythema were assessed and punch biopsies collected at weeks 4, 8, 12, and 16. At week 16, additional tissue was collected for biomechanical analyses and markers for inflammatory cytokines, extracellular matrix (ECM) proteins, re-epithelialization, pigmentation, and angiogenesis were quantified at all time points using qRT-PCR. Treatment with PDL, FX CO2 , or PDL + FX CO2 resulted in significantly less contraction versus skin graft only controls with no statistically significant difference among laser therapy groups. Scars treated with both PDL and FX CO2 were visually more erythematous than other groups with a significant increase in redness between two and three standard deviations above normal skin redness. Scars treated with FX CO2 were visually smoother and contained significantly fewer wrinkles. In addition, hyperpigmentation was significantly reduced in scars treated with FX CO2 . The use of fractional carbon dioxide or pulsed dye laser therapy within 1 month of autografting significantly reduced scar

  5. The effect of CO2 and Nd:YAP lasers on CAD/CAM Ceramics: SEM, EDS and thermal studies.

    Science.gov (United States)

    El Gamal, Ahmed; Fornaini, Carlo; Rocca, Jean Paul; Muhammad, Omid H; Medioni, Etienne; Cucinotta, Annamaria; Brulat-Bouchard, Nathalie

    2016-03-31

    The objective of this study was to investigate the interaction of infrared laser light on Computer Aided Design and Computer Aided Manufacturing (CAD/CAM) ceramic surfaces. Sixty CAD/CAM ceramic discs were prepared and divided into two different groups: lithiumdisilicate ceramic (IPSe.maxCADs) and Zirconia ceramic (IPSe.maxZirCADs). The laser irradiation was performed on graphite and non-graphite surfaces with a Carbon Dioxide laser at 5W and 10W power in continuous mode (CW mode) and with Neodymium Yttrium Aluminum Perovskite (Nd:YAP) laser at 10W. Surface textures and compositions were examined using Scanning Electron Microscopy (SEM), and Energy Dispersive Spectroscopy (EDS). Thermal elevation was measured by thermocouple during laser irradiation. The SEM observation showed a rough surface plus cracks and fissures on CO2 10W samples and melting areas in Nd:YAP samples; moreover, with CO2 5W smooth and shallow surfaces were observed. EDS analysis revealed that laser irradiation does not result in modifications of the chemical composition even if minor changes in the atomic mass percentage of the components were registered. Thermocouple showed several thermal changes during laser irradiation. CO2 and Nd:YAP lasers modify CAD/CAM ceramic surface without chemical composition modifications.

  6. Raman spectroscopy differentiates squamous cell carcinoma (SCC) from normal skin following treatment with a high-powered CO2 laser.

    Science.gov (United States)

    Fox, Sara A; Shanblatt, Ashley A; Beckman, Hugh; Strasswimmer, John; Terentis, Andrew C

    2014-12-01

    The number of cases of non-melanoma skin cancer (NMSC), which include squamous cell carcinoma (SCC) and basal cell carcinoma (BCC), continues to rise as the aging population grows. Mohs micrographic surgery has become the treatment of choice in many cases but is not always necessary or feasible. Ablation with a high-powered CO2 laser offers the advantage of highly precise, hemostatic tissue removal. However, confirmation of complete cancer removal following ablation is difficult. In this study we tested for the first time the feasibility of using Raman spectroscopy as an in situ diagnostic method to differentiate NMSC from normal tissue following partial ablation with a high-powered CO2 laser. Twenty-five tissue samples were obtained from eleven patients undergoing Mohs micrographic surgery to remove NMSC tumors. Laser treatment was performed with a SmartXide DOT Fractional CO2 Laser (DEKA Laser Technologies, Inc.) emitting a wavelength of 10.6 μm. Treatment levels ranged from 20 mJ to 1200 mJ total energy delivered per laser treatment spot (350 μm spot size). Raman spectra were collected from both untreated and CO2 laser-treated samples using a 785 nm diode laser. Principal Component Analysis (PCA) and Binary Logistic Regression (LR) were used to classify spectra as originating from either normal or NMSC tissue, and from treated or untreated tissue. Partial laser ablation did not adversely affect the ability of Raman spectroscopy to differentiate normal from cancerous residual tissue, with the spectral classification model correctly identifying SCC tissue with 95% sensitivity and 100% specificity following partial laser ablation, compared with 92% sensitivity and 60% selectivity for untreated NMSC tissue. The main biochemical difference identified between normal and NMSC tissue was high levels of collagen in the normal tissue, which was lacking in the NMSC tissue. The feasibility of a combined high-powered CO2 laser ablation, Raman diagnostic procedure for the

  7. Influence of water layer thickness on hard tissue ablation with pulsed CO2 laser.

    Science.gov (United States)

    Zhang, Xianzeng; Zhan, Zhenlin; Liu, Haishan; Zhao, Haibin; Xie, Shusen; Ye, Qing

    2012-03-01

    The theory of hard tissue ablation reported for IR lasers is based on a process of thermomechanical interaction, which is explained by the absorption of the radiation in the water component of the tissue. The microexplosion of the water is the cause of tissue fragments being blasted from hard tissue. The aim of this study is to evaluate the influence of the interdependence of water layer thickness and incident radiant exposure on ablation performance. A total of 282 specimens of bovine shank bone were irradiated with a pulse CO(2) laser. Irradiation was carried out in groups: without a water layer and with a static water layer of thickness ranging from 0.2 to 1.2 mm. Each group was subdivided into five subgroups for different radiant exposures ranging from 18 to 84 J/cm(2), respectively. The incision geometry, surface morphology, and microstructure of the cut walls as well as thermal injury were examined as a function of the water layer thickness at different radiant exposures. Our results demonstrate that the additional water layer is actually a mediator of laser-tissue interaction. There exists a critical thickness of water layer for a given radiant exposure, at which the additional water layer plays multiple roles, not only acting as a cleaner to produce a clean cut but also as a coolant to prevent bone heating and reduce thermal injury, but also helping to improve the regularity of the cut shape, smooth the cut surface, and enhance ablation rate and efficiency. The results suggest that desired ablation results depend on optimal selection of both water layer thickness and radiant exposure. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE).

  8. Efficient fabrication of fused-fiber biconical taper structures by a scanned CO2 laser beam technique.

    Science.gov (United States)

    Bayle, Fabien; Meunier, Jean-Pierre

    2005-10-20

    The driving mechanism of a scanning mirror can cause significant impairment of expanded beam properties, which we investigated for several scanning waveforms. Engineering on the scanning waveform is then carried out by a scanned CO2 laser beam technique to enlarge the uniform heating region for stretching and sintering of silica fibers. Details of the derivation are given. A simple thermal model is presented to account for the relationship between the scanning beam profile and the taper shape. Fusion profiles are also compared for various scanning waveforms. The corresponding scanned beam power distributions are determined experimentally, which enables us to determine precise power density conditions for CO2 laser fusion.

  9. Contact laser vaporization of the prostate for benign prostatic hypertrophy

    Science.gov (United States)

    Gomella, Leonard G.; Lotfi, M. A.; Milam, Douglas F.; Albala, David; Reagan, Gary

    1994-05-01

    The contact laser applications for the removal of the enlarged prostate are distinctly different than the majority of non-contact Nd:YAG lasers that rely on coagulation necrosis and delayed sloughing. Contact Nd:YAG laser allows cutting, coagulation and vaporization of tissue with minimal penetration beyond the contact surface. Using the contact laser prostatectomy technique, the contact laser probe directly touches and immediately vaporizes the prostatic tissue under the probe. The net result is the immediate removal of the obstructing tissue, in a manner similar to the standard electrosurgical TURP. This immediate removal of tissue offers the patient treated with the contact laser the potential for decreased catheter time and a more rapid resolution of symptoms. Our initial experience suggests that the contact technique may be better suited for the smaller prostate gland (i.e. less than 30 gm). The contact laser may also be used for a procedure termed the `laser assisted TURP': a standard electrosurgical TURP is performed and the contact laser is used for hemostasis. Several investigators have reported non-randomized results of the contact technique with good outcomes. A prospective randomized trial of the contact laser prostatectomy vrs the electrosurgical TURP is underway. The contact laser vaporization of the prostate holds great promise for the treatment of symptomatic benign prostatic hypertrophy: it is virtually bloodless and allows immediate visualization of the TUR defect.

  10. Bond strength of resin cement to CO2 and Er:YAG laser-treated zirconia ceramic

    Directory of Open Access Journals (Sweden)

    Shahin Kasraei

    2014-11-01

    Full Text Available Objectives It is difficult to achieve adhesion between resin cement and zirconia ceramics using routine surface preparation methods. The aim of this study was to evaluate the effects of CO2 and Er:YAG laser treatment on the bond strength of resin cement to zirconia ceramics. Materials and Methods In this in-vitro study 45 zirconia disks (6 mm in diameter and 2 mm in thickness were assigned to 3 groups (n = 15. In control group (CNT no laser treatment was used. In groups COL and EYL, CO2 and Er:YAG lasers were used for pretreatment of zirconia surface, respectively. Composite resin disks were cemented on zirconia disk using dual-curing resin cement. Shear bond strength tests were performed at a crosshead speed of 0.5 mm/min after 24 hr distilled water storage. Data were analyzed by one-way ANOVA and post hoc Tukey's HSD tests. Results The means and standard deviations of shear bond strength values in the EYL, COL and CNT groups were 8.65 ± 1.75, 12.12 ± 3.02, and 5.97 ± 1.14 MPa, respectively. Data showed that application of CO2 and Er:YAG lasers resulted in a significant higher shear bond strength of resin cement to zirconia ceramics (p < 0.0001. The highest bond strength was recorded in the COL group (p < 0.0001. In the CNT group all the failures were adhesive. However, in the laser groups, 80% of the failures were of the adhesive type. Conclusions Pretreatment of zirconia ceramic via CO2 and Er:YAG laser improves the bond strength of resin cement to zirconia ceramic, with higher bond strength values in the CO2 laser treated samples.

  11. CO2 laser and/or fluoride enamel treatment against in situ/ex vivo erosive challenge

    Directory of Open Access Journals (Sweden)

    Maísa Camillo JORDÃO

    Full Text Available ABSTRACT Objective This in situ/ex vivo study investigated the effect of CO2 laser irradiation and acidulated phosphate fluoride gel (APF application, separately and in combination, on enamel resistance to erosion. Material and Methods During 2 experimental 5-day crossover phases, 8 volunteers wore intraoral appliances containing bovine enamel blocks which were submitted to four groups: 1st phase - control, untreated and CO2 laser irradiation, 2nd phase - fluoride application and fluoride application before CO2 laser irradiation. Laser irradiation was performed at 10.6 µm wavelength, 5 µs pulse duration and 50 Hz frequency, with average power input and output of 2.3 W and 2.0 W, respectively (28.6 J/cm2. APF gel (1.23%F, pH 3.5 was applied on enamel surface with a microbrush and left on for 4 minutes. Then, the enamel blocks were fixed at the intraoral appliance level. The erosion was performed extraorally 4 times daily for 5 min in 150 mL of cola drink. Enamel loss was measured profilometrically after treatment and after the in situ phase. The data were tested using one-way Repeated Measures Anova and Tukey's test (p<0.05. Results CO2 laser alone (2.00±0.39 µm did not show any significantly preventive effect against enamel erosion when compared with the control group (2.41±1.20 µm. Fluoride treated enamel, associated (1.50±0.30 µm or not (1.47±0.63 µm with laser irradiation, significantly differed from the control. Conclusion The APF application decreased enamel wear; however, CO2 laser irradiation did not enhance fluoride ability to reduce enamel wear.

  12. Combination of intense pulsed light and fractional CO(2) laser treatments for patients with acne with inflammatory and scarring lesions.

    Science.gov (United States)

    Wang, B; Wu, Y; Luo, Y-J; Xu, X-G; Xu, T-H; Chen, J Z S; Gao, X-H; Chen, H-D; Li, Y-H

    2013-06-01

    Various laser and light sources are been used increasingly in cosmetic dermatology. To evaluate the efficacy and safety of combination intense pulsed light (IPL) and fractional CO2 laser in treating patients with acne with both inflammatory and scarring lesions. In total, 37 Chinese patients with acne with facial inflammatory and scar lesions were treated. Successive sessions of 4-6 IPL treatments followed by 2 sessions of fractional CO2 laser treatments were applied. Effectiveness was determined by the dermatologist's evaluation, patient self-assessment, and devices that measure skin colour, sebum secretion and skin hydration. IPL treatments significantly reduced the inflammatory lesion score and the atrophic scar score compared with baseline. Subsequent fractional CO2 laser treatments further decreased the atrophic scar score. Both scores remained low when patients were followed up at 6 months. Around 90% of the patients experienced significant or moderate overall improvement, and almost 80% patients rated their results as 'excellent' or 'good'. The melanin index (MI), erythema index (EI) and skin sebum level all significantly decreased after IPL treatments, and the EI and sebum level were still low when assessed at the 3-month follow-up, although the MI had increased again. The adverse effects (AEs) of both treatments were transient and bearable. IPL in combination with fractional CO2 laser was effective in treating patients with acne with both inflammatory lesions and atrophic scars, and the AEs were acceptable. © The Author(s) CED © 2013 British Association of Dermatologists.

  13. Treatment of atrophic facial scars with combined use of high-energy pulsed CO2 laser and Er:YAG laser: a practical guide of the laser techniques for the Er:YAG laser.

    Science.gov (United States)

    Cho, S I; Kim, Y C

    1999-12-01

    Although CO2 laser resurfacing provides substantial clinical improvement for atrophic facial scars, the CO2 laser often results in excessive thermal damage to the skin. It increases complications postoperatively. The Er:YAG laser ablates thinner layers of tissue than the CO2 laser with minimal thermal damage to the surrounding skin. To determine the efficacy of combined treatment of atrophic facial scars with high-energy pulsed CO2 laser and Er:YAG laser. One hundred fifty-eight patients were treated with a combination of high-energy pulsed CO2 laser and Er:YAG laser for atrophic facial scars. All patients were evaluated after 3 months of treatment. The scars improved 80-89% in 65 patients, 70-79% in 56 patients, more than 90% in 32 patients, 60-69% in 2 patients, and less than 60% in 3 patients after laser treatment. Treatment of atrophic facial scars with combined use of high-energy pulsed CO2 laser and Er:YAG laser is a very effective and useful method.

  14. Synthesis of single walled carbon nanotubes by dual laser vaporization

    CSIR Research Space (South Africa)

    Moodley, MK

    2006-07-01

    Full Text Available Single walled carbon nanotubes were synthesized by the laser vaporization of graphite composite targets in a tube furnace. Two pulsed Nd:Yag lasers operating at fundamental (1064 nm) and 2 nd harmonic (532 nm) were combined, focused and evaporated...

  15. Tunable single-longitudinal-mode operation of an injection-locked TEA CO2 laser. [ozone absorption spectroscopy

    Science.gov (United States)

    Megie, G.; Menzies, R. T.

    1979-01-01

    The tunable single-longitudinal-mode operation of a TEA CO2 laser by an injection technique using a CW waveguide laser as the master oscillator is reported. With the experimental arrangement described, in which the waveguide laser frequency is tuned to correspond to one of the oscillating longitudinal modes of the TEA laser, single-longitudinal-mode operation was achieved with no apparent reduction in the TEA output energy, on various CO2 lines with frequency offsets from the line center as large as 300 MHz. The capability of this technique for high-resolution spectroscopy or atmospheric lidar studies is demonstrated by the recording of the absorption spectrum of a strong ozone line.

  16. Selective Removal of Natural Occlusal Caries by Coupling Near-infrared Imaging with a CO2 Laser

    OpenAIRE

    Tao, You-Chen; Fried, Daniel

    2008-01-01

    Laser removal of dental hard tissue can be combined with optical, spectral or acoustic feedback systems to selectively ablate dental caries and restorative materials. Near-infrared (NIR) imaging has considerable potential for the optical discrimination of sound and demineralized tissue. Last year we successfully demonstrated that near-IR images can be used to guide a CO2 laser ablation system for the selective removal of artificial caries lesions on smooth surfaces. The objective of this stud...

  17. [Measurements of CO2 concentration at high temperature and pressure environments using tunable diode laser absorption spectroscopy].

    Science.gov (United States)

    Cai, Ting-Dong; Gao, Guang-Zhen; Wang, Min-Rui; Wang, Gui-Shi; Gao, Xiao-Ming

    2014-07-01

    The present research was planned to develop a method for species concentration measurements under high temperature and pressure environments. The characteristics of CO2 spectrum at high temperature and pressure were studied at first. Based on the research above, tunable diode-laser absorption of CO2 near 2.0 microm incorporating fixed-wavelength modulation spectroscopy with second-harmonic detection was used to provide a method for sensitive and accurate measurements of gas temperature and CO2 concentration at high temperature and pressure. Measurements were performed in a well-controlled high temperature and pressure static cell. The results show that the average error of the CO2 concentration measurements at 5 atm, 500 K and 10 atm, 1000 K is 4. 49%. All measurements show the accuracy and potential utility of the method for high temperature and pressure diagnostics.

  18. Fuzzy Logic Approach for the Prediction of Dross Formation in CO2 Laser Cutting of Mild Steel

    Directory of Open Access Journals (Sweden)

    Miloš Madić

    2015-11-01

    Full Text Available Dross free laser cutting is very important in the application of laser cutting technology. This paper focuses on the development of a fuzzy logic model to predict dross formation in CO2 laser oxygen cutting of mild steel. Laser cutting experiment, conducted according to Taguchi’s experimental design using L25 orthogonal array, provided a set of data for the development of a fuzzy rule base. The predicting fuzzy logic model is based on using Mamdani-type inference system. Developed fuzzy logic model considered the cutting speed, laser power and assist gas pressure as inputs. Using this model the effects of the selected laser cutting parameters on the dross formation were investigated. Additionally, 3-D surface plots were generated to study the interaction effects of the laser cutting parameters. The analysis revealed that the cutting speed has the most significant effect, followed by laser power and assist gas pressure. The results indicated that the fuzzy logic modeling approach can be effectively used for the dross formation prediction in CO2 laser cutting of mild steel.

  19. Fundamental study about CO2 laser welding of titanium aluminide intermetallic compound

    Science.gov (United States)

    Kuwahara, Gaku; Yamaguchi, Shigeru; Nanri, Kenzo; Ootani, Masanori; Tetsuka, Masato; Seto, Sachio; Arai, Mikiya; Fujioka, Tomoo

    2000-11-01

    Titanium aluminide intermetallic compound is attracting attentions as heat-resistant and high-specific strength material in the next generation, especially, it is promising material in the field of aerospace components. Conventional machining process including welding, however, can be hardly applied due to its very low ductility. The objective of this study, as a first stage, is to find out paying attention to crack and hardness the fundamental good conditions of the bead-on-plate welding of TiAl intermetallic compound using CO2 laser irradiation. In the experiment, we used the casting gamma titanium aluminide contained iron, vanadium and boron with a thickness of 2mm. We carried out bead-on-plate laser welding in the titanium aluminide material in inert gas environment filled with argon. We measured fused depth, Vickers hardness, transverse crack numbers and so on as major parameters of welding speed from 1000 to 4600 mm/min and initial temperature of specimen from R.T. to 873 K with a beam spot size of 0.5 mm and an output power of 1.5 kW. In addition, the specimens were analyzed by Electron Probe X-ray Micro Analyzer, Energy Dispersive X-ray Spectroscopy and X-ray Diffractometry. As a result of experiments, transverse crack-free welding was achieved, when initial temperature was at 873 K. In every condition, the value of Vickers hardness of fused zone increased compared with base. We think the reason of it is an increase of (alpha) 2(Ti3Al) phase, which is caused by rapid cooling, taking in Oxygen, fine structure and so on.

  20. Comparison of multiple rebond shear strengths of debonded brackets after preparation with sandblasting and CO2 laser

    Directory of Open Access Journals (Sweden)

    Mojgan Kachoei

    2016-08-01

    Full Text Available Background. Failure of orthodontic bracket bonds is a common occurrence during orthodontic treatment. Different techniques have been suggested in the literature to remove resin residues from the bracket bases and enamel surfaces to prepare the surfaces again after debonding. This study attempted to compare multiple rebond shear strengths (SBS of debonded brackets following preparation with sandblasting and CO2 laser. Methods. The brackets were bonded on 30 human and bovine maxillary central incisors using self-curing composite resin. SBS was measured using Hounsfield testing machine. The brackets were rebonded for two other times after composite resin residues on their surfaces were removed, either with air abrasion or CO2 laser. The debonded brackets and enamel surfaces were also evaluated after each debonding procedure under a stereomicroscope in order to determine adhesive remnant index (ARI. SBS of debonded brackets after each step were compared between sandblast and CO2 laser groups. Results. We observed significant differences in SBS values between pre-recycling and first (P = 0.04, second (P = 0.007 and third recycling (P = 0.007 with laser. Recycling with sandblasting resulted in a decrease in SBS after the first and second recycling procedure; however, the SBS increased after the third recycling procedure, with no significant differences. Conclusion. SBS of brackets after recycling with sandblasting and laser beams was not significantly different, and both were at a favorable level. However, repeating the recycling procedure with sandblasting resulted in more favorable SBS compared to laser.

  1. Measurement of the Nonlinearity of Heat-Flux Sensors Employing a CO_2 laser

    Science.gov (United States)

    van der Ham, E. W. M.; Beer, C. M.; Ballico, M. J.

    2018-01-01

    Heat-flux sensors are widely used in industry to test building products and designs for resistance to bushfire, to test the flammability of textiles and in numerous applications such as concentrated solar collectors. In Australia, such detectors are currently calibrated by the National Measurement Institute Australia (NMIA) at low flux levels of 20 W \\cdot m^{-2}. Estimates of the uncertainty arising from nonlinearity at industrial levels (e.g. 50 kW \\cdot m^{-2} for bushfire testing) rely on literature information. NMIA has developed a facility to characterize the linearity response of these heat-flux sensors up to 110 kW \\cdot m^{-2} using a low-power CO_2 laser and a chopped quartz tungsten-halogen lamp. The facility was validated by comparison with the conventional flux-addition method, and used to characterize several Schmidt-Boelter-type sensors. A significant nonlinear response was found, ranging from (3.2 ± 0.9)% at 40 kW \\cdot m^{-2} to more than 8 % at 100 kW \\cdot m^{-2}. Additional measurements confirm that this is not attributable to convection effects, but due to the temperature dependence of the sensor's responsivity.

  2. Nondestructive testing by using long-wave infrared interferometric techniques with CO2 lasers and microbolometer arrays.

    Science.gov (United States)

    Alexeenko, Igor; Vandenrijt, Jean-François; Pedrini, Giancarlo; Thizy, Cédric; Vollheim, Birgit; Osten, Wolfgang; Georges, Marc P

    2013-01-01

    We describe three different interferometric techniques (electronic speckle pattern interferometry, digital holographic interferometry, and digital shearography), using a long-wave infrared radiation produced by a CO(2) laser and recorded on a microbolometer array. Experimental results showing how these methods can be used for nondestructive testing are presented. Advantages and disadvantages of these approaches are discussed.

  3. TEA CO2 laser-induced reaction of CH3NO2 with CF2HCl: A ...

    Indian Academy of Sciences (India)

    Unknown

    vibrational energy transfer processes from the TEA CO2 laser-excited CF2HCl to. CH3NO2. Time-resolved infrared fluorescence from vibrationally excited CF2HCl and CH3NO2 molecules as well as UV absorption of CF2 radicals are carried out to elucidate the dynamics of excitation/dissociation and the chemical reactions ...

  4. CO2 Laser and Topical Fluoride Therapy in the Control of Caries Lesions on Demineralized Primary Enamel

    Directory of Open Access Journals (Sweden)

    R. A. Valério

    2015-01-01

    Full Text Available This study evaluated the effect of CO2 laser irradiation and topical fluoride therapy in the control of caries progression on primary teeth enamel. 30 fragments (3×3×2 mm from primary canines were submitted to an initial cariogenic challenge that consisted of immersion on demineralizing solution for 3 hours and remineralizing solution for 21 hours for 5 days. Fragments were randomly assigned into three groups (n=10: L: CO2 laser (λ=10.6 μm, APF: 1.23% acidulated phosphate fluoride, and C: no treatment (control. CO2 laser was applied with 0.5 W power and 0.44 J/cm2 energy density. Fluoride application was performed with 0.1 g for 1 minute. Cariogenic challenge was conducted for 5 days following protocol previously described. Subsurface Knoop microhardness was measured at 30 μm from the edge. Obtained data were subjected to analysis the variance (ANOVA and Duncan test with significance of 5%. It was found that the L group showed greater control of deciduous enamel demineralization and were similar to those of APF group, while being statistically different from C group (P≤0.05 that showed the lowest microhardness values. It was concluded that CO2 laser can be an additional resource in caries control progression on primary teeth enamel.

  5. CO2 laser and topical fluoride therapy in the control of caries lesions on demineralized primary enamel.

    Science.gov (United States)

    Valério, R A; Rocha, C T; Galo, R; Borsatto, M C; Saraiva, M C P; Corona, S A M

    2015-01-01

    This study evaluated the effect of CO2 laser irradiation and topical fluoride therapy in the control of caries progression on primary teeth enamel. 30 fragments (3 × 3 × 2 mm) from primary canines were submitted to an initial cariogenic challenge that consisted of immersion on demineralizing solution for 3 hours and remineralizing solution for 21 hours for 5 days. Fragments were randomly assigned into three groups (n = 10): L: CO2 laser (λ = 10.6 μm), APF: 1.23% acidulated phosphate fluoride, and C: no treatment (control). CO2 laser was applied with 0.5 W power and 0.44 J/cm(2) energy density. Fluoride application was performed with 0.1 g for 1 minute. Cariogenic challenge was conducted for 5 days following protocol previously described. Subsurface Knoop microhardness was measured at 30 μm from the edge. Obtained data were subjected to analysis the variance (ANOVA) and Duncan test with significance of 5%. It was found that the L group showed greater control of deciduous enamel demineralization and were similar to those of APF group, while being statistically different from C group (P ≤ 0.05) that showed the lowest microhardness values. It was concluded that CO2 laser can be an additional resource in caries control progression on primary teeth enamel.

  6. HIGHER LARYNGEAL PRESERVATION RATE AFTER CO(2) LASER SURGERY COMPARED WITH RADIOTHERAPY IN T1A GLOTTIC LARYNGEAL CARCINOMA

    NARCIS (Netherlands)

    Schrijvers, Michiel L.; van Riel, Eva L.; Langendijk, Johannes A.; Dikkers, Frederik G.; Schuuring, Ed; van der Wal, Jacqueline E.; van der Laan, Bernard F. A. M.

    Background. Clinical outcome of endoscopic CO(2) laser surgery and radiotherapy in early-stage glottic laryngeal carcinoma is difficult to compare because of differences in treatment selection and patient groups. Therefore, we compared local control, overall survival, and laryngeal preservation in a

  7. Selective laser vaporization of polypropylene sutures and mesh

    Science.gov (United States)

    Burks, David; Rosenbury, Sarah B.; Kennelly, Michael J.; Fried, Nathaniel M.

    2012-02-01

    Complications from polypropylene mesh after surgery for female stress urinary incontinence (SUI) may require tedious surgical revision and removal of mesh materials with risk of damage to healthy adjacent tissue. This study explores selective laser vaporization of polypropylene suture/mesh materials commonly used in SUI. A compact, 7 Watt, 647-nm, red diode laser was operated with a radiant exposure of 81 J/cm2, pulse duration of 100 ms, and 1.0-mm-diameter laser spot. The 647-nm wavelength was selected because its absorption by water, hemoglobin, and other major tissue chromophores is low, while polypropylene absorption is high. Laser vaporization of ~200-μm-diameter polypropylene suture/mesh strands, in contact with fresh urinary tissue samples, ex vivo, was performed. Non-contact temperature mapping of the suture/mesh samples with a thermal camera was also conducted. Photoselective vaporization of polypropylene suture and mesh using a single laser pulse was achieved with peak temperatures of 180 and 232 °C, respectively. In control (safety) studies, direct laser irradiation of tissue alone resulted in only a 1 °C temperature increase. Selective laser vaporization of polypropylene suture/mesh materials is feasible without significant thermal damage to tissue. This technique may be useful for SUI procedures requiring surgical revision.

  8. O emprego do laser de CO2 no controle da cárie dentária = The use of CO2 laser on dental on dental caries control

    Directory of Open Access Journals (Sweden)

    Rodrigues, Lidiany Karla Azevedo

    2007-01-01

    Full Text Available O laser de dióxido de carbono atua na inibição da desmineralização do esmalte, reduzindo sua solubilidade aos ácidos e, este efeito pode ser potencializado quando associado a agentes fluoretados. Assim, o objetivo deste trabalho foi descrever as características do laser de CO2, discutir os mecanismos de ação do laser na inibição da desmineralização do esmalte e ainda, revisar a literatura a respeito de seus efeitos quando combinado ao íon flúor

  9. Fractional CO2 laser is as effective as Q-switched ruby laser for the initial treatment of a traumatic tattoo.

    Science.gov (United States)

    Seitz, Anna-Theresa; Grunewald, Sonja; Wagner, Justinus A; Simon, Jan C; Paasch, Uwe

    2014-12-01

    Q-switched laser treatments are considered the standard method for removing both regular and traumatic tattoos. Recently, the removal of tattoo ink using ablative fractional lasers has been reported. Ablative fractional CO2 laser and q-switched ruby laser treatments were used in a split-face mode to compare the safety and efficacy of the two types of laser in removing a traumatic tattoo caused by the explosion of a firework. A male patient suffering from a traumatic tattoo due to explosive deposits in his entire face was subjected to therapy. A series of eleven treatments were performed. The right side of the face was always treated using an ablative fractional CO2 laser, whereas the left side was treated only using a q-switched ruby laser. After a series of eleven treatments, the patient demonstrated a significant lightening on both sides of his traumatic tattoo, with no clinical difference. After the first six treatments, the patient displayed greater lightening on the right side of his face, whereas after another five treatments, the left side of the patient's face appeared lighter. No side effects were reported. In the initial stage of removing the traumatic tattoo, the ablative fractional laser treatment appeared to be as effective as the standard ruby laser therapy. However, from the 6th treatment onward, the ruby laser therapy was more effective. Although ablative fractional CO2 lasers have the potential to remove traumatic tattoos, they remain a second-line treatment option.

  10. Development of a laser remote sensing instrument to measure sub-aerial volcanic CO2 fluxes

    Science.gov (United States)

    Queisser, Manuel; Burton, Mike

    2016-04-01

    A thorough quantification of volcanic CO2 fluxes would lead to an enhanced understanding of the role of volcanoes in the geological carbon cycle. This would enable a more subtle understanding of human impact on that cycle. Furthermore, variations in volcanic CO2 emissions are a key to understanding volcanic processes such as eruption phenomenology. However, measuring fluxes of volcanic CO2 is challenging as volcanic CO2 concentrations are modest compared with the ambient CO2 concentration (~400 ppm) . Volcanic CO2 quickly dilutes with the background air. For Mt. Etna (Italy), for instance, 1000 m downwind from the crater, dispersion modelling yields a signal of ~4 ppm only. It is for this reason that many magmatic CO2 concentration measurements focus on in situ techniques, such as direct sampling Giggenbach bottles, chemical sensors, IR absorption spectrometers or mass spectrometers. However, emission rates are highly variable in time and space. Point measurements fail to account for this variability. Inferring 1-D or 2-D gas concentration profiles, necessary to estimate gas fluxes, from point measurements may thus lead to erroneous flux estimations. Moreover, in situ probing is time consuming and, since many volcanoes emit toxic gases and are dangerous as mountains, may raise safety concerns. In addition, degassing is often diffuse and spatially extended, which makes a measurement approach with spatial coverage desirable. There are techniques that allow to indirectly retrieve CO2 fluxes from correlated SO2 concentrations and fluxes. However, they still rely on point measurements of CO2 and are prone to errors of SO2 fluxes due to light dilution and depend on blue sky conditions. Here, we present a new remote sensing instrument, developed with the ERC project CO2Volc, which measures 1-D column amounts of CO2 in the atmosphere with sufficient sensitivity to reveal the contribution of magmatic CO2. Based on differential absorption LIDAR (DIAL) the instrument measures

  11. A fast, easy circumcision procedure combining a CO2 laser and cyanoacrylate adhesive: a non-randomized comparative trial

    Directory of Open Access Journals (Sweden)

    Tahsin Gorgulu

    2016-02-01

    Full Text Available ABSTRACT Background Circumcision is performed as a routine operation in many countries, more commonly for religious and cultural reasons than for indicated conditions, such as phimosis and balanitis. There are many techniques available, and recently electrocautery and both Nd:YAG and CO2 lasers, instead of blades, have been used for skin and mucosal incisions. However, the infection risk in circumcisions performed using a CO2 laser was 10% higher. There are also reports of sutureless procedures using cyanoacrylate, but these have higher risks of hematoma and hemorrhage. We combined a CO2 laser and cyanoacrylate to shorten the operation time and to decrease bleeding complications. Materials and Methods : Circumcisions were performed under general anesthesia with CO2 laser and cyanoacrylate combination in 75 6–9-year-old boys between May 2013 and August 2014 only for religious reasons. As a control, we compared them retrospectively with 75 age-matched patients who were circumcised using the conventional guillotine method in our clinic. Results No hematomas, bleeding, or wound infections were observed. One wound dehiscence (1.33% occurred during the early postoperative period and healed without any additional procedures. The median operating time was 7 (range 6–9 minutes. The conventional guillotine group comprised one hematoma (1.3%, two wound dehiscences (2.6%, and two hemorrhages (2.6%, and the median operating time was 22 (range 20–26 minutes. The difference in surgical time was significant (p<0.001, with no significant difference in the rate of complications between the two groups. Conclusion The combined CO2 laser and cyanoacrylate procedure not only decreased the operating time markedly, but also eliminated the disadvantages associated with each individual procedure alone.

  12. CO2laser-induced bump formation and growth on polystyrene for multi-depth soft lithography molds

    KAUST Repository

    Li, Huawei

    2012-10-19

    This paper reports the process of creating bumps on the surface of polystyrene (PS) induced by a CO2laser at low powers. The paper also outlines the procedure for growing bumps induced by multiple laser scans on the aforementioned bumps. These bumps result from the net volume gain of the laser heat-affected zone on the PS rather than from a deposition process, and the expansion of the heat-affected zone on PS was verified by measuring the hardness change using nanoindentation. The bumps have a much smoother surface than microchannels fabricated with laser cutting; depending on the laser power, they have heights ranging from hundreds of nanometers to 42m. The laser scanning speed and scan times along with this technique offer a fast and low-cost alternative for fabricating molds for multi-depth PDMS microfluidic devices. © 2012 IOP Publishing Ltd.

  13. Laser-induced chemical vapor deposition of nanostructured silicon carbonitride thin films

    Science.gov (United States)

    Besling, W. F. A.; Goossens, A.; Meester, B.; Schoonman, J.

    1998-01-01

    Laser-induced chemical vapor deposition of silicon carbonitride thin films has been investigated using a continuous wave CO2 laser in parallel configuration with the substrate. The reactant gases in this process, hexamethyl disilazane and ammonia, are rapidly heated by CO2 laser radiation due to their absorption of the laser energy. Polymerlike silicon carbonitride films or agglomerated nanosized particles are formed depending on process conditions. Dense, smooth films or nanostructured deposits have been synthesized at low substrate temperatures (Tssilicon and can be obtained with controlled microstructures. Surface morphology, composition, and type of chemical bonding have been studied with electron microscopy and spectroscopic analysis and are correlated to the most important laser process parameters. X-ray photoelectron spectroscopy and reflectance Fourier transform infrared spectroscopy show that the deposits consist of Si-N, Si-C, and Si-O bonds, linked together in a x-ray amorphous, polymerlike structure. The nitrogen content is about 40% and can be varied by adding ammonia to the reactant gas flow. The layers are readily contaminated with oxygen after exposure to air, caused by hydrolysis and/or oxidation.

  14. CO2-laser micromachining and back-end processing for rapid production of PMMA-based microfluidic systems

    DEFF Research Database (Denmark)

    Klank, Henning; Kutter, Jörg Peter; Geschke, Oliver

    2002-01-01

    , a three-layer polymer microstructure with included optical fibers was fabricated within two days. The use of CO2-laser systems to produce microfluidic systems has not been published before. These systems provide a cost effective alternative to UV-laser systems and they are especially useful...... for microstructured PMMA [poly( methyl methacrylate)] parts were investigated, such as solvent-assisted glueing, melting, laminating and surface activation using a plasma asher. A solvent-assisted thermal bonding method proved to be the most time-efficient one. Using laser micromachining together with bonding...

  15. Experimental and numerical investigations on the density profile of CO2 laser-produced Sn plasma for an EUVL source

    Science.gov (United States)

    Tao, Y.; Ueno, Y.; Yuspeh, S.; Burdt, R. A.; Amin, N.; Shaikh, N. M.; Tillack, M. S.; Najmabadi, F.

    2010-04-01

    Experimentally observed density profile of CO2 laser-produced Sn plasma was compared with that predicted by one dimensional hydrodynamic radiation numerical code. Experimental data showed a much smaller corona and a much shorter shift distance of the critical density from the initial target surface as compared with those predicted by an isothermal model and the numerical simulation. The possible reason may come from thin localized laser deposition region, less energy transport into the corona and into the dense region beyond the critical density. This research suggests that more efforts to understand the fundamental dominating the interaction of CO2 laser with high Z plasma are necessary to form a more solid foundation for the application of numerical method to the development of the EUVL source.

  16. Temporal characterization of plasma cw high-power CO2 laser-matter interaction: contribution to the welding process control

    Science.gov (United States)

    Engel, Thierry; Kane, M.; Fontaine, Joel

    1997-08-01

    During high-power laser welding, gas ionization occurs above the sample. The resulting plasma ignition threshold is related to ionization potential of metallic vapors from the sample, and shielding gases used in the process. In this work, we have characterized the temporal behavior of the radiation emitted by the plasma during laser welding in order to relate the observed signals to the process parameters.

  17. Effect of CO2 and Nd:YAG Lasers on Shear Bond Strength of Resin Cement to Zirconia Ceramic

    Directory of Open Access Journals (Sweden)

    Shahin Kasraei

    2016-05-01

    Full Text Available Objectives: Because of poor bond between resin cement and zirconia ceramics, laser surface treatments have been suggested to improve adhesion. The present study evaluated the effect of CO2 and Nd:YAG lasers on the shear bond strength (SBS of resin cement to zirconia ceramic.Materials and Methods: Ninety zirconia disks (6×2 mm were randomly divided into six groups of 15. In the control group, no surface treatment was used. In the test groups, laser surface treatment was accomplished using CO2 and Nd:YAG lasers, respectively (groups two and three. Composite resin disks (3×2 mm were fabricated and cemented to zirconia disks with self-etch resin cement and stored in distilled water for 24 hours. In the test groups four-six, the samples were prepared as in groups one-three and then thermocycled and stored in distilled water for six months. The SBS tests were performed (strain rate of 0.5 mm/min. The fracture modes were observed via stereomicroscopy. Data were analyzed with one and two-way ANOVA, independent t and Tukey’s tests.Results: The SBS values of Nd:YAG group (18.95±3.46MPa was significantly higher than that of the CO2 group (14.00±1.96MPa, but lower than that of controls (23.35±3.12MPa. After thermocycling and six months of water storage, the SBS of the untreated group (1.80±1.23 MPa was significantly lower than that of the laser groups. In groups stored for 24 hours, 60% of the failures were adhesive; however, after thermocycling and six months of water storage, 100% of failures were adhesive.Conclusion: Bonding durability of resin cement to zirconia improved with CO2 and Nd:YAG laser surface treatment of zirconia ceramic.

  18. All-fiber versatile laser frequency reference at 2 μm for CO2 space-borne lidar applications

    Science.gov (United States)

    Schilt, Stéphane; Matthey, Renaud; Hey Tow, Kenny; Thévenaz, Luc; Südmeyer, Thomas

    2017-12-01

    We present a frequency stabilized laser at 2051 nm based on a versatile all-fibered stabilization setup. A modulation sideband locking technique is implemented to lock the laser at a controlled frequency detuning from the center of the CO2 R(30) transition envisaged for space-borne differential absorption lidar (DIAL) applications. This method relies on the use of a compact all-fibered gas reference cell that makes the setup robust and immune to mechanically induced optical misalignments. The gas cell is fabricated using a hollow-core photonic crystal fiber filled with pure CO2 at a low pressure of 20 mbar and hermetically sealed at both ends by splices to silica fibers. Different configurations of this fibered cell have been developed and are presented. With this technique, frequency stabilities below 40 kHz at 1-s integration time and laser detuning by around 1 GHz from the center of the CO2 transition. These stabilities are compliant with typical requirements for the reference seed source for a space CO2 DIAL.

  19. All-fiber versatile laser frequency reference at 2 μm for CO2 space-borne lidar applications

    Science.gov (United States)

    Schilt, Stéphane; Matthey, Renaud; Hey Tow, Kenny; Thévenaz, Luc; Südmeyer, Thomas

    2017-06-01

    We present a frequency stabilized laser at 2051 nm based on a versatile all-fibered stabilization setup. A modulation sideband locking technique is implemented to lock the laser at a controlled frequency detuning from the center of the CO2 R(30) transition envisaged for space-borne differential absorption lidar (DIAL) applications. This method relies on the use of a compact all-fibered gas reference cell that makes the setup robust and immune to mechanically induced optical misalignments. The gas cell is fabricated using a hollow-core photonic crystal fiber filled with pure CO2 at a low pressure of 20 mbar and hermetically sealed at both ends by splices to silica fibers. Different configurations of this fibered cell have been developed and are presented. With this technique, frequency stabilities below 40 kHz at 1-s integration time and <100 kHz up to 1000-s averaging time were achieved for a laser detuning by around 1 GHz from the center of the CO2 transition. These stabilities are compliant with typical requirements for the reference seed source for a space CO2 DIAL.

  20. Thermal detection thresholds of Aδ- and C-fibre afferents activated by brief CO2 laser pulses applied onto the human hairy skin

    National Research Council Canada - National Science Library

    Churyukanov, Maxim; Plaghki, Léon; Legrain, Valéry; Mouraux, André

    2012-01-01

    .... Here, using a novel CO(2) laser stimulator able to deliver constant-temperature heat pulses through a feedback regulation of laser power by an online measurement of skin temperature at target site, combined with an adaptive...

  1. Rotationally resolved IR-diode laser studies of ground-state CO2 excited by collisions with vibrationally excited pyridine.

    Science.gov (United States)

    Johnson, Jeremy A; Kim, Kilyoung; Mayhew, Maurine; Mitchell, Deborah G; Sevy, Eric T

    2008-03-27

    Relaxation of highly vibrationally excited pyridine (C5NH5) by collisions with carbon dioxide has been investigated using diode laser transient absorption spectroscopy. Vibrationally hot pyridine (E' = 40,660 cm(-1)) was prepared by 248 nm excimer laser excitation followed by rapid radiationless relaxation to the ground electronic state. Pyridine then collides with CO2, populating the high rotational CO2 states with large amounts of translational energy. The CO2 nascent rotational population distribution of the high-J (J = 58-80) tail of the 00(0)0 state was probed at short times following the excimer laser pulse to measure rate constants and probabilities for collisions populating these CO2 rotational states. Doppler spectroscopy was used to measure the CO2 recoil velocity distribution for J = 58-80 of the 00(0)0 state. The energy-transfer distribution function, P(E,E'), from E' - E approximately 1300-7000 cm(-1) was obtained by re-sorting the state-indexed energy-transfer probabilities as a function of DeltaE. P(E,E') is fit to an exponential or biexponential function to determine the average energy transferred in a single collision between pyridine and CO2. Also obtained are fit parameters that can be compared to previously studied systems (pyrazine, C6F6, methylpyrazine, and pyrimidine/CO2). Although the rotational and translational temperatures that describe pyridine/CO2 energy transfer are similar to previous systems, the energy-transfer probabilities are much smaller. P(E,E') fit parameters for pyridine/CO2 and the four previously studied systems are compared to various donor molecular properties. Finally, P(E,E') is analyzed in the context of two models, one indicating that P(E,E') shape is primarily determined by the low-frequency out-of-plane donor vibrational modes, and the other that indicates that P(E,E') shape can be determined from how the donor molecule final density of states changes with DeltaE.

  2. LASER EMISSIONS FROM CO2 VIBRATIONAL TRANSITIONS IN A LOW TEMPERATURE SUPERSONIC FLOW EXCITED BY A PULSED ELECTRON BEAM STABILIZED DISCHARGE

    OpenAIRE

    Fontaine, B.; Forestier, B.; Gross, P.; Koudriavtsev, E.

    1980-01-01

    High power long pulse infrared laser emission has been achieved on CO2 molecule with the high density and very low temperature supersonic flow-electron beam-stabilized discharge excitation device developped at I.M.F.M. ([MATH] [MATH] 2 amagats, T [MATH] 70 - 150 K). Laser emission at [MATH] = 10.6 µ has been achieved for a resonant cavity set at the discharge location and also 3 cm downstream of the discharge location. With Ar/CO2, Ar/CO2/H2, He/CO2, and He/CO2/N2 mixtures, lasing energy and ...

  3. High-brightness picosecond ion beam source based on BNL Terawatt CO2 laser: Proof-of-principle experiments

    Energy Technology Data Exchange (ETDEWEB)

    Shkolnikov, Peter

    2012-10-04

    Under the continuing DOE support, we have: o assembled the basic experiment setup and then continued expanding it to include diverse diagnostics and to accommodate gas jet targets in addition to metal foils; o conducted an extensive study of our novel laser, significantly enhanced laser beam diagnostics, and improved relevant laser parameters; o turned our experiments into a truly international endeavor with active collaboration of close to 20 researchers in US, UK, and Germany; o conducted the first ever experiments with proton and ion acceleration by lasers interacting with overcritical plasma of gas jets; o for the first time directly observed radiation pressure acceleration of protons, including quasi-monoenergetic spectra promising for future applications; o for the first time directly observed quasi-stable, bubble-like plasma structures that likely evolved from relativistic laser-plasma solitons (post-solitons). Thus, we have confirmed a strong potential of a picosecond TW CO2 laser as a research tool in laser-plasma science and as a promising vehicle for future applications of laser ion acceleration. This has led to apparent increase of the interest in mid-IR laser ion acceleration. In particular, another major research group began extensive proton acceleration experiments with their own CO2 laser at UCLA. As a result, the mechanisms responsible for laser proton acceleration in gas jets have become somewhat clearer. It is also important to note that modest DOE funding played the role of a seed support ensuring the formation of a multinational research team, whose members contributed its time and equipment with value well in excess of that seed amount.

  4. Treatment of tooth fracture by medium-energy CO2 laser and DP-bioactive glass paste: the interaction of enamel and DP-bioactive glass paste during irradiation by CO2 laser.

    Science.gov (United States)

    Lin, C P; Tseng, Y C; Lin, F H; Liao, J D; Lan, W H

    2001-03-01

    Acute trauma or trauma associated with occlusal disturbance can produce tooth crack or fracture. Although several methods are proposed to treat the defect, however, the prognosis is generally poor. If the fusion of a tooth fracture by laser is possible, it will offer an alternative to extraction or at least serve as an adjunctive treatment in the reconstruction. We have tried to use a continuous-wave CO2 laser and a newly developed DP-bioactive glass paste (DPGP) to fuse or bridge tooth crack or fracture lines. Both the DP-bioactive glass paste and tooth enamel have strong absorption bands at the wavelength of 10.6 microm. Therefore, under CO2 laser, DPGP and enamel should have an effective absorption and melt together. The interface between DPGP and enamel could be regarded as a mixture of DPGP and enamel (DPG-E). The study focused on the phase transformation, microstructure, functional group and thermal behavior of DPG-E with or without CO2 laser irradiation, by the analytical techniques of XRD, FTIR, DTA/TGA, and SEM. The results of XRD showed that the main crystal phase in the DPG-E was dicalcium phosphate dihydrate (CaHPO4.2H2O). It changed into CaHPO4, gamma-Ca2P2O7, beta-Ca2P2O7 and finally alpha-Ca2P2O7 with increasing temperature. In the FTIR analysis, the 720 cm(-1) absorption band ascribed to the P-O-P linkage in pyrophosphate rose up and the intensities of the OH- bands reduced after laser irradiation. In regard to the results of DTA/TGA after irradiation, the weight loss decreased due to the removal of part of absorption water and crystallization water by the CO2 laser. SEM micrographs revealed that the melted masses and the plate-like crystals formed a tight chemical bond between the enamel and DPGP. We expect that DPGP with the help of CO2 laser can be an alternative to the treatment of tooth crack or fracture.

  5. Energy balance in laser-irradiated vaporizing droplets.

    Science.gov (United States)

    Zardecki, A; Armstrong, R L

    1988-09-01

    The interactions of vaporizing aerosols with a high energy laser beam are analyzed in the diffusive vaporization regime. This is the regime in which diffusive mass transport and conductive energy transport dominate the aerosol-beam interactions. A numerical analysis of the coupled aerosol-beam equations allows us to compute the energy conversion of the incident laser pulse. The plots showing the functional form of the pulse shape and the fractional energy conversion are given to illustrate the interactions for a wide range of pulse energies. A new term describing the droplet radius shrinking in time, similar in form to that recently analyzed by Davies and Brock, is included.

  6. Single photon ionization of van der Waals clusters with a soft x-ray laser: (CO2)n and (CO2)n(H2O)m.

    Science.gov (United States)

    Heinbuch, S; Dong, F; Rocca, J J; Bernstein, E R

    2006-10-21

    Pure neutral (CO2)n clusters and mixed (CO2)n(H2O)m clusters are investigated employing time of flight mass spectroscopy and single photon ionization at 26.5 eV. The distribution of pure (CO2)n clusters decreases roughly exponentially with increasing cluster size. During the ionization process, neutral clusters suffer little fragmentation because almost all excess cluster energy above the vertical ionization energy is taken away by the photoelectron and only a small part of the photon energy is deposited into the (CO2)n cluster. Metastable dissociation rate constants of (CO2)n+ are measured in the range of (0.2-1.5) x 10(4) s(-1) for cluster sizes of 5CO2-H2O clusters are studied under different generation conditions (5% and 20% CO2 partial pressures and high and low expansion pressures). At high CO2 concentration, predominant signals in the mass spectrum are the (CO2)n+ cluster ions. The unprotonated cluster ion series (CO2)nH2O+ and (CO2)n(H2O)2+ are also observed under these conditions. At low CO2 concentration, protonated cluster ions (H2O)nH+ are the dominant signals, and the protonated CO2(H2O)nH+ and unprotonated (H2O)n+ and (CO2)(H2O)n+ cluster ion series are also observed. The mechanisms and dynamics of the formation of these neutral and ionic clusters are discussed.

  7. Electrospun Polymer Fiber Lasers for Applications in Vapor Sensing

    DEFF Research Database (Denmark)

    Krämmer, Sarah; Laye, Fabrice; Friedrich, Felix

    2017-01-01

    A sensing approach based on laser emissionfrom polymer fiber networks is presented. Poly(methyl methacrylate) (PMMA) fibers doped with a laser dye are fabricated by electrospinning. They form random loop resonators, which show laser emission upon optical pumping. The shift of the spectral positio...... in the transient shift of the lasing peaks can be used to discriminate ethanol and methanol vapor in mixtures of them. The sensing mechanism is expected to be applicable to other solvent vapors that cause polymer swelling.......A sensing approach based on laser emissionfrom polymer fiber networks is presented. Poly(methyl methacrylate) (PMMA) fibers doped with a laser dye are fabricated by electrospinning. They form random loop resonators, which show laser emission upon optical pumping. The shift of the spectral position...... feature excellent sensing performance due to the large overlap (more than 80%) of light field and transducer. The shift of the laser modes results from the swelling of the polymer when exposed to solvent vapors. Due to distinctly different diffusion coefficients in polymers, the uptake dynamics reflected...

  8. Effect of the focal plane position on CO2 laser beam cutting of injection molded polycarbonate sheets

    Science.gov (United States)

    Moradi, Mahmoud; Mehrabi, Omid; Azdast, Taher; Benyounis, Khaled Y.

    2016-11-01

    In the present research, the effect of laser beam focal plane position (FPP) on the kerf quality of the polycarbonate laser cutting is investigated. Low power CO2 laser is used as the heat source of the cutting runs. In the experiments, FPP is varied from 0 to -4mm while other processing parameters (i.e. laser power, cutting speed and gas pressure) are considered constant. Upper and lower kerf width, kerf taper, upper heat affected zone and surface roughness of the kerf wall are also considered as the responses. Observations signified that reducing the position of the laser beam focal point from zero to - 3mm reduces the upper and lower kerf width. However reducing FPP below -3mm leads to an increase in the kerf width. Results also reveals that upper heat affected zone value reduces by reduction in FPP. Moreover the best kerf wall surface roughness occurred at FPP= -3mm.

  9. Effects of CO2 laser irradiation on matrix-rich biofilm development formation–an in vitro study

    Directory of Open Access Journals (Sweden)

    Bruna Raquel Zancopé

    2016-11-01

    Full Text Available Background A carbon dioxide (CO2 laser has been used to morphologically and chemically modify the dental enamel surface as well as to make it more resistant to demineralization. Despite a variety of experiments demonstrating the inhibitory effect of a CO2 laser in reduce enamel demineralization, little is known about the effect of surface irradiated on bacterial growth. Thus, this in vitro study was preformed to evaluate the biofilm formation on enamel previously irradiated with a CO2 laser (λ = 10.6 µM. Methods For this in vitro study, 96 specimens of bovine enamel were employed, which were divided into two groups (n = 48: 1 Control-non-irradiated surface and 2 Irradiated enamel surface. Biofilms were grown on the enamel specimens by one, three and five days under intermittent cariogenic condition in the irradiated and non-irradiated surface. In each assessment time, the biofilm were evaluated by dry weigh, counting the number of viable colonies and, in fifth day, were evaluated by polysaccharides analysis, quantitative real time Polymerase Chain Reaction (PCR as well as by contact angle. In addition, the morphology of biofilms was characterized by fluorescence microscopy and field emission scanning electron microscopy (FESEM. Initially, the assumptions of equal variances and normal distribution of errors were conferred and the results are analyzed statistically by t-test and Mann Whitney test. Results The mean of log CFU/mL obtained for the one-day biofilm evaluation showed that there is statistical difference between the experimental groups. When biofilms were exposed to the CO2 laser, CFU/mL and CFU/dry weight in three day was reduced significantly compared with control group. The difference in the genes expression (Glucosyltransferases (gtfB and Glucan-binding protein (gbpB and polysaccharides was not statically significant. Contact angle was increased relative to control when the surface was irradiated with the CO2 laser. Similar

  10. Formation of plano-convex micro-lens array in fused silica glass using CO2 laser assisted reshaping technique

    CERN Document Server

    Sohn, Ik-Bu; Yoo, Dongyoon; Noh, Young-Chul; Ahsan, Md Shamim; Sung, Jae-Hee; Lee, Seong-Ku

    2016-01-01

    We report on fabricating high-fill-factor plano-convex spherical and square micro-lens arrays on fused silica glass surface using CO2 laser assisted reshaping technique. Initially, periodic micro-pillars have been encoded on the glass surface by means of a femtosecond laser beam. Afterwards, the micro-pillars are polished several times by irradiating a CO2 laser beam on top of the micro-pillars. Consequently, spherical micro-lens array with micro-lens size of 50 um x 50 um and square micro-lens array with micro-lens size of 100 um x 100 um are formed on fused silica glass surface. We also study the intensity distribution of light passed through the spherical micro-lens array engraved glass sample. The simulation result shows that, the focal length of the spherical micro-lens array is 35 um. Furthermore, we investigate the optical properties of the micro-lens array engraved glass samples. The proposed CO2 laser based reshaping technique is simple and fast that shows promises in fabrication arrays of smooth mic...

  11. Exogenous bFGF or TGFβ1 accelerates healing of reconstructed dura by CO2 laser soldering in minipigs.

    Science.gov (United States)

    Wang, Zhenmin; Zhong, Hongliang; Yang, Zhijun; Zhao, Fu; Wang, Bo; Qu, Peiran; Liu, Pinan

    2014-05-01

    This study aims to explore the probable mechanism of better result of dural reconstruction by CO2 laser soldering and the effect of exogenous basic fibroblast growth factor (bFGF) or transforming growth factor-beta1(TGFβ1) on wound healing. In part I of the study, ten minipigs were randomized into two equal groups, and the dural defects were reconstructed by conventional fibrin glue (FG) bonding (group I a) or by CO2 laser soldering (group Ib). In part II, 36 minipigs were randomized into three equal groups, and the dural defect was reconstructed by CO2 laser soldering; then exogenous bFGF or TGFβ1 was administered in group IIb and group IIc, respectively, while group IIa served as control group. The dural specimens were harvested at 1st week postoperatively in part I; and at 1st, 2nd, 3rd, and 4th week postoperatively in part II, they were examined for healing condition and subjected to hematoxylin-eosin (HE) staining and immunohistochemical (IHC) staining with antibodies against bFGF and TGFβ1. In part I, group Ib showed higher fibroblast cell density than group Ia (P laser may trigger fibroblast proliferation through stimulating the secretion of bFGF and TGFβ1. Topically administering exogenous bFGF or TGFβ1 could accelerate the healing of the reconstructed dura by enhancing secretion of bFGF and/or TGFβ1 and promoting the process of fibroblast gathering-degrading.

  12. Harmonic scalpel versus flexible CO2 laser for tongue resection: A histopathological analysis of thermal damage in human cadavers

    Directory of Open Access Journals (Sweden)

    Wolf Tamir

    2011-08-01

    Full Text Available Abstract Background Monopolar cautery is the most commonly used surgical cutting and hemostatic tool for head and neck surgery. There are newer technologies that are being utilized with the goal of precise cutting, decreasing blood loss, reducing thermal damage, and allowing faster wound healing. Our study compares thermal damage caused by Harmonic scalpel and CO2 laser to cadaveric tongue. Methods Two fresh human cadaver heads were enrolled for the study. Oral tongue was exposed and incisions were made in the tongue akin to a tongue tumor resection using the harmonic scalpel and flexible C02 laser fiber at various settings recommended for surgery. The margins of resection were sampled, labeled, and sent for pathological analysis to assess depth of thermal damage calculated in millimeters. The pathologist was blinded to the surgical tool used. Control tongue tissue was also sent for comparison as a baseline for comparison. Results Three tongue samples were studied to assess depth of thermal damage by harmonic scalpel. The mean depth of thermal damage was 0.69 (range, 0.51 - 0.82. Five tongue samples were studied to assess depth of thermal damage by CO2 laser. The mean depth of thermal damage was 0.3 (range, 0.22 to 0.43. As expected, control samples showed 0 mm of thermal damage. There was a statistically significant difference between the depth of thermal injury to tongue resection margins by harmonic scalpel as compared to CO2 laser, (p = 0.003. Conclusion In a cadaveric model, flexible CO2 laser fiber causes less depth of thermal damage when compared with harmonic scalpel at settings utilized in our study. However, the relevance of this information in terms of wound healing, hemostasis, safety, cost-effectiveness, and surgical outcomes needs to be further studied in clinical settings.

  13. Microleakage in Class V Composite Restorations after Desensitizing Surface Treatment with Er:YAG and