Impact of combined CO2 laser irradiation and fluoride on enamel and dentin biofilm-induced mineral loss.

Science.gov (United States)

Esteves-Oliveira, Marcella; El-Sayed, Karim Fawzy; Dörfer, Christof; Schwendicke, Falk

2017-05-01

The caries-protective effects of CO 2 laser irradiation on dental enamel have been demonstrated using chemical demineralization models. We compared the effect of CO 2 laser irradiation, sodium fluoride, or both on biofilm-induced mineral loss (∆Z) and Streptococcus mutans adhesion to enamel and dentin in vitro. Ground, polished bovine enamel, and dentin samples were allocated to four groups (n = 12/group): no treatment (C); single 22,600-ppm fluoride (F) varnish (5 % NaF) application; single CO 2 laser treatment (L) with short pulses (5 μs/λ = 10.6 μm); and laser and subsequent fluoride treatment (LF). Samples were sterilized and submitted to an automated mono-species S. mutans biofilm model. Brain heart infusion plus 5 % sucrose medium was provided eight times daily, followed by rinses with artificial saliva. After 10 days, bacterial numbers in biofilms were enumerated as colony-forming units/ml (CFU/ml) (n = 7/group). ∆Z was assessed using transversal microradiography (n = 12/group). Univariate ANOVA with post hoc Tukey honestly-significant-difference test was used for statistical analysis. Bacterial numbers were significantly higher on dentin than enamel (p  0.05). In dentin, only LF (163/227) significantly reduced ∆Z (p fluoride application was required to protect dentin.

Laser Ablation of Biological Tissue Using Pulsed CO2 Laser

International Nuclear Information System (INIS)

Hashishin, Yuichi; Sano, Shu; Nakayama, Takeyoshi

2010-01-01

Laser scalpels are currently used as a form of laser treatment. However, their ablation mechanism has not been clarified because laser excision of biological tissue occurs over a short time scale. Biological tissue ablation generates sound (laser-induced sound). This study seeks to clarify the ablation mechanism. The state of the gelatin ablation was determined using a high-speed video camera and the power reduction of a He-Ne laser beam. The aim of this study was to clarify the laser ablation mechanism by observing laser excision using the high-speed video camera and monitoring the power reduction of the He-Ne laser beam. We simulated laser excision of a biological tissue by irradiating gelatin (10 wt%) with radiation from a pulsed CO 2 laser (wavelength: 10.6 μm; pulse width: 80 ns). In addition, a microphone was used to measure the laser-induced sound. The first pulse caused ablation particles to be emitted in all directions; these particles were subsequently damped so that they formed a mushroom cloud. Furthermore, water was initially evaporated by laser irradiation and then tissue was ejected.

Silicon isotope separation utilizing infrared multiphoton dissociation of Si2F6 irradiated with two-color CO2 laser light

International Nuclear Information System (INIS)

Yokoyama, Atsushi; Ohba, Hironori; Hashimoto, Masashi; Arai, Shigeyoshi

2002-01-01

Silicon isotope separation has been done by utilizing the Infrared Multiphoton Dissociation (IRMPD) of Si 2 F 6 irradiated with two-color CO 2 laser lights. The two-color excitation method improved the separation efficiency keeping the high enrichment factors. For example, 99.74% of 28 Si was obtained at 49.63% dissociation of Si 2 F 6 after the simultaneous irradiation of 200 pulses with 966.23 cm -1 photons (0.084 J/cm 2 ) and 954.55 cm -1 photons (0.658 J/cm 2 ), while 2000 pulses were needed to obtain 99.35% of 28 Si at 35.6% dissociation in the case of only one-color irradiation at 954.55 cm -1 (0.97 J/cm 2 ). (author)

Thermal damage produced by high-irradiance continuous wave CO2 laser cutting of tissue.

Science.gov (United States)

Schomacker, K T; Walsh, J T; Flotte, T J; Deutsch, T F

1990-01-01

Thermal damage produced by continuous wave (cw) CO2 laser ablation of tissue in vitro was measured for irradiances ranging from 360 W/cm2 to 740 kW/cm2 in order to investigate the extent to which ablative cooling can limit tissue damage. Damage zones thinner than 100 microns were readily produced using single pulses to cut guinea pig skin as well as bovine cornea, aorta, and myocardium. Multiple pulses can lead to increased damage. However, a systematic decrease in damage with irradiance, predicted theoretically by an evaporation model of ablation, was not observed. The damage-zone thickness was approximately constant around the periphery of the cut, consistent with the existence of a liquid layer which stores heat and leads to tissue damage, and with a model of damage and ablation recently proposed by Zweig et al.

Surface morphological modification of crosslinked hydrophilic co-polymers by nanosecond pulsed laser irradiation

Energy Technology Data Exchange (ETDEWEB)

Primo, Gastón A.; Alvarez Igarzabal, Cecilia I. [IMBIV (CONICET), Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Edificio de Ciencias II, Ciudad Universitaria, Córdoba X5000HUA (Argentina); Pino, Gustavo A.; Ferrero, Juan C. [INFIQC (CONICET), Departamento de Fisicoquímica, Facultad de Ciencias Químicas, and Centro Láser de Ciencias Moleculares, Universidad Nacional de Córdoba, Córdoba X5000IUS (Argentina); Rossa, Maximiliano, E-mail: mrossa@fcq.unc.edu.ar [INFIQC (CONICET), Departamento de Fisicoquímica, Facultad de Ciencias Químicas, and Centro Láser de Ciencias Moleculares, Universidad Nacional de Córdoba, Córdoba X5000IUS (Argentina)

2016-04-30

Graphical abstract: - Highlights: • Laser-induced surface modification of crosslinked hydrophilic co-polymers by ns pulses. • Formation of ablation craters observed under most of the single-pulse experimental conditions. • UV laser foaming of dried hydrogel samples resulting from single- and multiple-pulse experiments. • Threshold values of the incident laser fluence reported for the observed surface modifications. • Lower threshold fluences for acrylate-based, compared to acrylamide-based hydrogels. - Abstract: This work reports an investigation of the surface modifications induced by irradiation with nanosecond laser pulses of ultraviolet and visible wavelengths on crosslinked hydrophilic co-polymeric materials, which have been functionalized with 1-vinylimidazole as a co-monomer. A comparison is made between hydrogels differing in the base co-monomer (N,N-dimethylaminoethyl methacrylate and N-[3-(dimethylamino)propyl] methacrylamide) and in hydration state (both swollen and dried states). Formation of craters is the dominant morphological change observed by ablation in the visible at 532 nm, whereas additional, less aggressive surface modifications, chiefly microfoams and roughness, are developed in the ultraviolet at 266 nm. At both irradiation wavelengths, threshold values of the incident laser fluence for the observation of the various surface modifications are determined under single-pulse laser irradiation conditions. It is shown that multiple-pulse irradiation at 266 nm with a limited number of laser shots can be used alternatively for generating a regular microfoam layer at the surface of dried hydrogels based on N,N-dimethylaminoethyl methacrylate. The observations are rationalized on the basis of currently accepted mechanisms for laser-induced polymer surface modification, with a significant contribution of the laser foaming mechanism. Prospective applications of the laser-foamed hydrogel matrices in biomolecule immobilization are suggested.

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

Science.gov (United States)

Bahrololoomi, Zahra; Fotuhi Ardakani, Faezeh; Sorouri, Milad

2015-08-01

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. 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. 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 (Pdiode laser and 1W CO2 laser, 5W and 7W diode laser, or 1W and 2W CO2 laser in this regard. The results showed that enamel surface irradiation by CO2 and diode lasers increases the fluoride uptake.

Angle-dependent light emission from aligned multiwalled carbon nanotubes under CO2 laser irradiation

International Nuclear Information System (INIS)

Zhang, Y; Gong, T; Liu, W J; Wei, J Q; Zhang, X F; Wang, K L; Zhong, M L; Wu, D H

2007-01-01

This paper reports the light emission from aligned multiwalled carbon nanotubes (MWNTs) under continuous wave CO 2 laser (λ = 10.6 μm) irradiation. Results indicate that the light emission is dependent on the angle θ between the laser incident direction and the nanotube axis. The relative intensity of the light emission at certain wavelengths shows a Lorentzian feature when θ varies from 0 0 to 90 0 . The Lorentzian fitting curve displays a distinct tendency between shorter (λ 700 nm). A minimum intensity was observed at θ m close to 67 0 under shorter wavelength, whereas a maximum intensity was shown at θ m of about 60 0 at longer wavelength. These results show the anisotropic property of aligned MWNTs

Femtosecond laser irradiation of the fluorescent molecules-loaded poly(lactic-co-glycolic acid)

Science.gov (United States)

Umemoto, Taiga; Shibata, Akimichi; Terakawa, Mitsuhiro

2017-09-01

Molecular release from scaffolds is desired for tailoring cell-compatible tissue engineering. Several methods have been proposed to control molecular release, such as annealing, plasma treatment, and laser processing. In this study, we describe the alteration of Rhodamine B (RhB)-loaded poly(lactic-co-glycolic acid) (PLGA) after femtosecond laser irradiation, which was evaluated on the basis of the water absorption and mass remaining. Fluorescence measurement of released RhB molecules revealed the acceleration of the molecular release upon 400-nm laser irradiation, whereas 800-nm laser irradiation did not induce a comparable degree of change compared with non-irradiated samples. The result of the water absorption measurement indicates that the large amount of water absorption of 400-nm laser-irradiated PLGA sample may accelerate the diffusion of the loaded molecules through absorbing water, which resulted in the faster molecular release.

The synergistic effects of CO2 laser treatment with calcium silicate cement of antibacterial, osteogenesis and cementogenesis efficacy

International Nuclear Information System (INIS)

Hsu, T-T; Yang, J-J; Kao, C-T; Huang, T-H; Chen, Y-W; Shie, M-Y

2015-01-01

Calcium silicate-based material (CS) has been successfully used in dental clinical applications. Some researches show that the antibacterial effects of CO 2 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 CO 2 laser irradiation on CS, with regard to both material characterization and human periodontal ligament cell (hPDLs) viability. CS was irradiated with a dental CO 2 laser using directly mounted fiber optics in 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 d to set. The hPDLs cultured on CS were analyzed, along with their proliferation and odontogenic differentiation behaviors. The results indicate that the CO 2 laser irradiation increased the amount of Ca and Si ions released from the CS, and regulated cell behavior. CO 2 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 CO 2 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. (letter)

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.

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

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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.

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.

Effect of CPP-ACP paste with and without CO2 laser irradiation on demineralized enamel microhardness and bracket shear bond strength

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Nasrin Farhadian

Full Text Available ABSTRACT Introduction: Many patients seeking orthodontic treatment already have incipient enamel lesions and should be placed under preventive treatments. The aim of this in vitro study was to evaluate the effect of CPP-ACP paste and CO2 laser irradiation on demineralized enamel microhardness and shear bond strength of orthodontic brackets. Methods: Eighty caries-free human premolars were subjected to a demineralization challenge using Streptococcus mutans. After demineralization, the samples were randomly divided into five equal experimental groups: Group 1 (control, the brackets were bonded without any surface treatment; Group 2, the enamel surfaces were treated with CPP-ACP paste for 4 minutes before bonding; Group 3, the teeth were irradiated with CO2 laser beams at a wavelength of 10.6 µm for 20 seconds. The samples in Groups 4 and 5 were treated with CO2 laser either before or through CPP-ACP application. SEM photomicrographs of a tooth from each group were taken to observe the enamel surface. The brackets were bonded to the buccal enamel using a conventional method. Shear bond strength of brackets and ARI scores were measured. Vickers microhardness was measured on the non-bonded enamel surface. Data were analyzed with ANOVA and Tukey test at the p< 0.05 level. Results: The mean shear bond strength and microhardness of the laser group were higher than those in the control group and this difference was statistically significant (p< 0.05. All groups showed a higher percentage of ARI score 4. Conclusion: CO2 laser at a wavelength of 10.6 µm significantly increased demineralized enamel microhardness and enhanced bonding to demineralized enamel.

Comparison of effects of diode laser and CO2 laser on human teeth and their usefulness in topical fluoridation.

Science.gov (United States)

González-Rodríguez, Alberto; de Dios López-González, Juan; del Castillo, Juan de Dios Luna; Villalba-Moreno, Juan

2011-05-01

Various authors have reported more effective fluoridation from the use of lasers combined with topical fluoride than from conventional topical fluoridation. Besides the beneficial effect of lasers in reducing the acid solubility of an enamel surface, they can also increase the uptake of fluoride. The study objectives were to compare the action of CO(2) and GaAlAs diode lasers on dental enamel and their effects on pulp temperature and enamel fluoride uptake. Different groups of selected enamel surfaces were treated with amine fluoride and irradiated with CO(2) laser at an energy power of 1 or 2 W or with diode laser at 5 or 7 W for 15 s each and compared to enamel surfaces without treatment or topical fluoridated. Samples were examined by means of environmental scanning electron microscopy (ESEM). Surfaces of all enamel samples were then acid-etched, measuring the amount of fluoride deposited on the enamel by using a selective ion electrode. Other enamel surfaces selected under the same conditions were irradiated as described above, measuring the increase in pulp temperature with a thermocouple wire. Fluorination with CO(2) laser at 1 W and diode laser at 7 W produced a significantly greater fluoride uptake on enamel (89 ± 18 mg/l) and (77 ± 17 mg/l) versus topical fluoridation alone (58 ± 7 mg/l) and no treatment (20 ± 1 mg/l). Diode laser at 5 W produced a lesser alteration of the enamel surface compared to CO(2) laser at 1 W, but greater pulp safety was provided by CO(2) laser (ΔT° 1.60° ± 0.5) than by diode laser (ΔT° 3.16° ± 0.6). Diode laser at 7 W and CO(2) laser at 2 W both caused alterations on enamel surfaces, but great pulp safety was again obtained with CO(2) (ΔT° 4.44° ± 0.60) than with diode (ΔT° 5.25° ± 0.55). Our study demonstrates that CO(2) and diode laser irradiation of the enamel surface can both increase fluoride uptake; however, laser energy parameters must be carefully

367 cases of CO2 laser therapy on facial acne

Science.gov (United States)

Gao, Yunqing; Liu, Songhao; Zhang, You; Liu, T. C.

1996-09-01

Since 1989, we have cured 367 persons of facial acne of different course by using direct irradiation of high-power CO2 laser combing with operative therapy of low-power CO2 laser. The cure rate is 100 percent. In this paper, we stated the therapeutic approach. It was shown that this therapeutic approach is simple and effective, and its recurrence rate is zero. There are no cicatrices after healing. It is easy to accept it, and is worthy of extension.

CO2-laser fusion

International Nuclear Information System (INIS)

Stark, E.E. Jr.

1978-01-01

The basic concept of laser fusion is described, with a set of requirements on the laser system. Systems and applications concepts are presented and discussed. The CO 2 laser's characteristics and advantages for laser fusion are described. Finally, technological issues in the development of CO 2 laser systems for fusion applications are discussed

Ethylene tetrafluoroethylene nanofibers prepared by CO2 laser supersonic drawing

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A. Suzuki

2013-06-01

Full Text Available Ethylene tetrafluoroethylene (ETFE nanofibers were prepared by carbon dioxide (CO2 laser irradiation of asspun ETFE fibers with four different melt flow rates (MFRs in a supersonic jet that was generated by blowing air into a vacuum chamber through the fiber injection orifice. The drawability and superstructure of fibers produced by CO2 laser supersonic drawing depend on the laser power, the chamber pressure, the fiber injection speed, and the MFR. Nanofibers obtained using a laser power of 20 W, a chamber pressure of 20 kPa, and an MFR of 308 g•10 min–1 had an average diameter of 0.303 µm and a degree of crystallinity of 54%.

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.

Silicon isotope separation utilizing infrared multiphoton dissociation of Si{sub 2}F{sub 6} irradiated with two-color CO{sub 2} laser light

Energy Technology Data Exchange (ETDEWEB)

Yokoyama, Atsushi; Ohba, Hironori; Hashimoto, Masashi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Ishii, Takeshi; Ohya, Akio [Nuclear Development Corp., Tokai, Ibaraki (Japan); Arai, Shigeyoshi [Hill Research Co. Ltd., Tokyo (Japan)

2002-08-01

Silicon isotope separation has been done by utilizing the Infrared Multiphoton Dissociation (IRMPD) of Si{sub 2}F{sub 6} irradiated with two-color CO{sub 2} laser lights. The two-color excitation method improved the separation efficiency keeping the high enrichment factors. For example, 99.74% of {sup 28}Si was obtained at 49.63% dissociation of Si{sub 2}F{sub 6} after the simultaneous irradiation of 200 pulses with 966.23 cm{sup -1} photons (0.084 J/cm{sup 2}) and 954.55 cm{sup -1} photons (0.658 J/cm{sup 2}), while 2000 pulses were needed to obtain 99.35% of {sup 28}Si at 35.6% dissociation in the case of only one-color irradiation at 954.55 cm{sup -1} (0.97 J/cm{sup 2}). (author)

Colour and chemical changes of the lime wood surface due to CO{sub 2} laser thermal modification

Energy Technology Data Exchange (ETDEWEB)

Kubovský, Ivan, E-mail: kubovsky@tuzvo.sk; Kačík, František

2014-12-01

Highlights: • Influences of CO{sub 2} laser on lime wood surface were studied. • With growth of the irradiation dose brightness decrease and increase of the total colour difference were observed. • Cellulose degradation and loss of hemicelluloses were observed. • Higher values at the input energy lead to accelerating the mutual reaction of the functional groups resulting in the subsequent condensation of lignin. • CO{sub 2} laser irradiation can be used as a new colouring method. - Abstract: We studied colour and main wood components changes of lime wood caused by CO{sub 2} laser beam irradiation. The dry surface of lime wood (Tilia vulgaris L.) was irradiated with the CO{sub 2} laser beam (wavelength of 10.6 μm) at different exposures (expressed as the irradiation dose). Colour changes were monitored by the spectrophotometer, chemical changes were observed by the ATR-FTIR spectroscopy and carbohydrates were analysed by the HPLC method. With the growth of the irradiation dose (from 8.1 to 28.7 J cm{sup −2}) lightness (ΔL{sup *}) decrease and increase of the total colour difference (ΔE{sup *}) were observed. Higher values of the input energy lead to accelerating the mutual reaction of the functional groups resulting in the subsequent condensation of lignin. The total decrease in saccharides at the highest irradiation dose reaches 27.39% of the initial amount of saccharides in the reference sample. We have observed degradation and loss of hemicelluloses.

Thermal stress in dentin and enamel under CO2 laser irradiation

Science.gov (United States)

Meyer, Dirk H.; Foth, Hans-Jochen

1996-01-01

Ablation of dentin and tartar was studied under carbon dioxide-laser irradiation in cw and pulse mode with pulse length down to 150 microseconds. The specimens had been cut by a diamant blade to slices of thicknesses between 0.8 and 2.8 mm. The laser induced temperature rise was measured by an infrared camera monitoring the backside of the samples. The specimens shape and structure at the laser spot was analyzed by electron microscopy. Of special interest was the testing of the SwiftLaseTM to reducing the heat. The experimental results show the necessity of a water cooling in all application modes. The origin of the cracks which had been observed in many of the samples, is currently under investigation.

Tritium recovery from co-deposited layers using 193-nm laser

Science.gov (United States)

Shu, W. M.; Kawakubo, Y.; Nishi, M. F.

Recovery of tritium from co-deposited layers formed in deuterium-tritium plasma operations of the TFTR (Tokamak Fusion Test Reactor) was investigated by the use of an ArF excimer laser operating at the wavelength of 193 nm. At the laser energy density of 0.1 J/cm2, a transient spike of the tritium-release rate was observed at initial irradiation. Hydrogen isotopes were released in the form of hydrogen-isotope molecules during the laser irradiation in vacuum, suggesting that tritium can be recovered readily from the released gases. In a second experiment, hydrogen (tritium) recovery from the co-deposited layers on JT-60 tiles that had experienced hydrogen-plasma operations was investigated by laser ablation with a focused beam of the excimer laser. The removal rate of the co-deposited layers was quite low when the laser energy density was smaller than the ablation threshold (1.0 J/cm2), but reached 1.1 μm/pulse at the laser energy density of 7.6 J/cm2. The effective absorption coefficient in the co-deposited layers at the laser wavelength was determined to be 1.9 μm-1. The temperature of the surface during the irradiation at the laser energy density of 0.5 J/cm2 was measured on the basis of Planck's law of radiation, and the maximum temperature during the irradiation decreased from 3570 K at the initial irradiation to 2550 K at the 1000th pulse of the irradiation.

Holographic interferometry of isolated deuterium plasmas produced by a CO2 laser

International Nuclear Information System (INIS)

Gatenby, P.V.; Walker, A.C.

1978-10-01

The application of double exposure fractional fringe holographic interferometry to measurements of electron density in a plasma generated by irradiation of a freely falling pellet of solid deuterium with a focused CO 2 laser pulse is discussed. A particularly simple technique is used for processing and reconstructing the holograms and this is described in detail. A summary and discussion of the results is included with the emphasis on the observed evolution of the deuterium plasma over the duration of the laser irradiation. (author)

Potential of CO2 lasers (10.6 µm associated with fluorides in inhibiting human enamel erosion

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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.

CO2弱激光照射减轻正畸治疗疼痛的临床研究%Clinical studies of CO2 Laser in Reducing Pain in Orthodontics

Institute of Scientific and Technical Information of China (English)

韩晶莹; 刘丽媛; 展望; 陆晓丽; 周珊; 贾莉

2011-01-01

Objective:To investigate the effect of local CO2 laser irradiation on orthodontic pain for the patients with first arch wires. Methods s 60 patients wearing fixed appliance were included in this study, 34 patients accepted local CO2 laser irradiation and 26 patients as a control group. Patients were then instructed to rate their levels of pain on a visual analog scale over time. Results:The level of orthodontic pain in local CO2 laser irradiation group were significantly lower than the control group. Conclusions Local CO2 laser irradiation will reduce pain associated with orthodontic force application.%目的:探计CO2弱激光局部照射减轻正畸治疗疼痛的临床效果.方法:选择60例固定矫治患者,激光照射组34例、对照组26例,使用视觉模拟评分法(VAS)评价CO2激光局部照射在矫治初始弓丝放置后不同时间点患者的疼痛程度.结果；应用CO2弱激光局部照射组患者的正畸疼痛程度明显低于对照组患者.结论:CO2激光局部照射可以减轻固定矫治患者治疗过程中的疼痛.

The investigations of nanoclusters and micron-sized periodic structures created at the surface of the crystal and amorphous silica by resonant CO2 laser irradiation

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Mukhamedgalieva A.F.

2017-01-01

Full Text Available The creation of nanoclasters and micrometer sized periodical structures at the surface of silica (crystal quartz and fused quartz by action of pulsed CO2 laser radiation (pulse energy of 1 J, pulse time of 70 ns have been investigated. The laser action on the surface of samples lead to appearance of two kind of structures – periodical micron-sized structures with the period length close to wave length of CO2 laser irradiation and nanoclusters with size close to 50-100 nanometers. This creation connects with the intensive ablation of matter at the maxima of standing waves which are a results of the interference of falling and surfaces waves. This connects with the resonant absorption of infrared laser radiation by silicate minerals.

In vitro evaluation of the morphologic changes on the root dentine irradiated by CO2 laser associated or not to calcium hydroxide application

International Nuclear Information System (INIS)

Romano, Ana Cristina Cury Camargo

2003-01-01

This in vitro study has evaluated the structural changes on the root dentine irradiated by a CO 2 laser associated or not to calcium hydroxide application, from the irradiated surface analysis by means of Scanning Electronic Microscopy (SEM). The purpose of this evaluation has been the study of an alternative method for the treatment of dentine hypersensitivity. Fourteen human teeth were utilized, third molars, divided into 7 groups. Group I (control group) to which no treatment was applied; Groups II, III and IV were given an application of Ca (OH) 2 paste followed by C0 2 laser irradiation, lasting 5 seconds each with intervals of 10 seconds between each application, with continuous emission, power of 0.5 W (Group II), 1.0 W (Group III), and 1.5 W (Group IV); Groups V, VI, and VII were given laser irradiations without the Ca (OH) 2 paste following the same parameters applied to groups II, III, and IV respectively. Morphologic changes suggesting to fusion and re-solidification have been observed, as well as the presence of material obstructing the whole analyzed surface on groups II, III, and IV (laser + Ca (OH) 2 ). As for groups V, VI, and VII, it has been observed fusion, re-solidification, and cracks, and these results being statistically significant when compared the '(Ca (OH) 2 )' groups to the laser groups. No statistically significant differences were observed regarding the different powers applied in the groups that used the same treatment. Despite this result, it can be stated that powers above 1.0 W (DP = 125,38 W/cm 2 ) are unfavorable due to the undesirable morphologic alterations and aesthetic compromising. (author)

Gaseous saturable absorbers for the Helios CO2 laser system

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Haglund, R.F. Jr.; Nowak, A.V.; Czuchlewski, S.J.

1981-01-01

Saturable absorbers are widely used to suppress parasitic oscillations in large-aperture, high-power CO 2 fusion-laser systems. We report experimental results on SF 6 -based gaseous saturable absorbers used for parasitic suppression in the eight-beam, 10 kJ Helios fusion-laser system. The gas mix effectively quenches self-lasing in the 9 and 10 μm branches of the CO 2 laser spectrum while simultaneously allowing high transmission of subnanosecond multiwavelength pulses for target-irradiation experiments. The gas isolator now in use consists of SF 6 and the additional fluorocarbons: 1, 1-difluoroethane (FC-152a); dichlorodifluoromethane (FC-12); chloropentafluoroethane (FC-115); 1,1-dichloro 2,2-difluoroethylene (FC-1112a); chlorotrifluoroethylene (FC-1113); and perfluorocyclobutane (FC-C318). The saturation of the mix was studied as a function of incident fluence, pressure, cell length, and incident wavelength. Experimental results are presented on the saturation properties of pure SF 6 and FC-152a and compared with the saturation behavior of CO 2 at 400 0 C

Effect of CO2 Laser and Fluoride Varnish Application on Microhardness of Enamel Surface Around Orthodontic Brackets.

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Mahmoudzadeh, Majid; Rezaei-Soufi, Loghman; Farhadian, Nasrin; Jamalian, Seyed Farzad; Akbarzadeh, Mahdi; Momeni, Mohammadali; Basamtabar, Masome

2018-01-01

Introduction: Orthodontic treatment has many advantages such as esthetic improvement and self-esteem enhancement; yet it has some disadvantages such as increasing the risk of formation of white spot lesions, because it makes oral hygiene more difficult. It is rational to implement procedures to prevent these lesions. The present study was aimed to assess the effect of CO 2 laser and fluoride varnish on the surface of the enamel surface microhardness around the orthodontic braces. Methods: Eighty extracted premolar teeth were selected, scaled, polished with nonfluoridated pumic and metal brackets were bonded to them. Then, they were randomly allocated to 5 groups: control (neither fluoride nor laser is used on enamel surfaces), fluoride (4 minutes fluoride varnish treatment of the enamel surfaces), CO 2 laser (10.6 µm CO 2 laser irradiation of the teeth), laserfluoride (fluoride application after laser irradiation) and fluoride-laser (fluoride was applied and then teeth were irradiated with laser). After surface treatment around brackets on enamel, the samples were stored in 0.1% thymol for less than 5 days and then they were exposed to a 10-day microbiological caries model. Microhardness values of enamel were evaluated with Vickers test. One sample of each group (5 teeth from 80 samples) was prepared for SEM (scanning electron microscopy) and the data from 75 remaining teeth were analyzed with analysis of variance (ANOVA) and chi-square tests (α =0.05). Results: Microhardness mean values from high to low were as follow: fluoride-laser, laser-fluoride, laser, fluoride and control. Microhardness in fluoride-laser group was significantly higher compared with that of the control group. Distribution adhesive remnant index (ARI) scores were significantly different between groups and most of bond failures occurred at the enamel-adhesive interface in groups 2 to 5 and at the adhesive-bracket interface in the control group. Conclusion: Combination of fluoride varnish and

Tritium decontamination from co-deposited layer on tungsten substrate by ultra violet lamp and laser

International Nuclear Information System (INIS)

Oya, Yasuhisa; Tadokoro, Takahiro; Shu, Wataru; Hayashi, Takumi; O'hira, Shigeru; Nishi, Masataka

2001-01-01

Tritium decontamination using ultra violet (UV) lamp and laser was performed. Simulated co-deposited layer on tungsten substrate was deposited by C 2 H 2 or C 2 D 2 glow discharge. The co-deposited layer was irradiated to UV lights from a xenon excimer lamp (172 nm) or ArF excimer laser (193 nm) and the in-situ decontamination behavior was evaluated by a mass spectrometer. After the UV irradiation, the hydrogen concentration in the co-deposited layer was evaluated by elastic recoil detection analysis (ERDA) and the depth profile was analyzed by secondary ion mass spectrometry (SIMS). For the co-deposited layer formed by C 2 D 2 glow discharge, it was found that M/e 3 (HD) gas was released mainly during the UV lamp irradiation while both M/e 3 (HD) and M/e 4 (D 2 ) gases were detected during the UV laser irradiation. Though the co-deposited layer was not removed by UV lamp irradiation, almost all the co-deposited layer was removed by UV laser irradiation within 1 min. The ratio of hydrogen against carbon in the co-deposited layer was estimated to be 0.53 by ERDA and the number of photon needed for removing 1 μm thick co-deposited layer was calculated to be 3.7x10 18 cm -2 for the UV laser by SIMS measurement. It is concluded that C-H (C-D) bond on the co-deposited layer were dissociated by irradiation of UV lamp while the co-deposited layer itself was removed by the UV laser irradiation. (author)

Direct biological effects of fractional ultrapulsed CO2 laser irradiation on keratinocytes and fibroblasts in human organotypic full-thickness 3D skin models.

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Schmitt, L; Huth, S; Amann, P M; Marquardt, Y; Heise, R; Fietkau, K; Huth, L; Steiner, T; Hölzle, F; Baron, J M

2018-05-01

Molecular effects of various ablative and non-ablative laser treatments on human skin cells-especially primary effects on epidermal keratinocytes and dermal fibroblasts-are not yet fully understood. We present the first study addressing molecular effects of fractional non-sequential ultrapulsed CO 2 laser treatment using a 3D skin model that allows standardized investigations of time-dependent molecular changes ex vivo. While histological examination was performed to assess morphological changes, we utilized gene expression profiling using microarray and qRT-PCR analyses to identify molecular effects of laser treatment. Irradiated models exhibited dose-dependent morphological changes resulting in an almost complete recovery of the epidermis 5 days after irradiation. On day 5 after laser injury with a laser fluence of 100 mJ/cm 2 , gene array analysis identified an upregulation of genes associated with tissue remodeling and wound healing (e.g., COL12A1 and FGF7), genes that are involved in the immune response (e.g., CXCL12 and CCL8) as well as members of the heat shock protein family (e.g., HSPB3). On the other hand, we detected a downregulation of matrix metalloproteinases (e.g., MMP3), differentiation markers (e.g., LOR and S100A7), and the pro-inflammatory cytokine IL1α.Overall, our findings substantiate the understanding of time-dependent molecular changes after CO 2 laser treatment. The utilized 3D skin model system proved to be a reliable, accurate, and reproducible tool to explore the effects of various laser settings both on skin morphology and gene expression during wound healing.

Ablation of polytetrafluoroethylene using a continuous CO2 laser beam

International Nuclear Information System (INIS)

Tolstopyatov, E M

2005-01-01

The ablation of polytetrafluoroethylene (PTFE) is studied using a continuous CO 2 laser beam of 30-50 W at a mean intensity of 0.05-50 MW m -2 . The ablation products and changes in the target layer are examined using infrared spectroscopy, x-ray photoelectron spectroscopy, x-ray diffraction and electron microscopy. The main experiments were conducted with an unfocused beam of intensity 0.9-1.2 MW m -2 . The radiation-polymer interaction characteristics were found to change appreciably as the ablation conditions are approached. Within the polymer layer, light scattering diminishes and true resonant light absorption increases. Two distinct polymer components, which differ primarily in their resistance to CO 2 laser radiation, were found to exist under ablation conditions. The less stable component depolymerizes intensively, while the more resistant component is blown up into fibres by intense gas flow. The reasons behind this behaviour are discussed. Preliminary gamma irradiation of PTFE is found to have a significant influence on the laser ablation process

Recent developments in CO2 lasers

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Du, Keming

1993-05-01

CO2 lasers have been used in industry mainly for such things as cutting, welding, and surface processing. To conduct a broad spectrum of high-speed and high-quality applications, most of the developments in industrial CO2 lasers at the ILT are aimed at increasing the output power, optimizing the beam quality, and reducing the production costs. Most of the commercial CO2 lasers above 5 kW are transverse-flow systems using dc excitation. The applications of these lasers are limited due to the lower beam quality, the poor point stability, and the lower modulation frequency. To overcome the problems we developed a fast axial- flow CO2 laser using rf excitation with an output of 13 kW. In section 2 some of the results are discussed concerning the gas flow, the discharge, the resonator design, optical effects of active medium, the aerodynamic window, and the modulation of the output power. The first CO2 lasers ever built are diffusion-cooled systems with conventional dc excited cylindrical discharge tubes surrounded by cooling jackets. The output power per unit length is limited to 50 W/m by those lasers with cylindrical tubes. In the past few years considerable increases in the output power were achieved, using new mechanical geometries, excitation- techniques, and resonator designs. This progress in diffusion-cooled CO2 lasers is presented in section 3.

Experimental research and observation of the skin response of mice with a second-degree scald during irradiation by a CO2 laser

Science.gov (United States)

Wang, Yunxia; Wu, Shulian; Li, Zhifang; Xu, Xiaohui; Li, Hui

2014-05-01

Second-degree scalding is a common dermatological injury. Inappropriate treatment methods in clinical practice always produce scarring, and can lead to skin cancer and other complications in the longer term. In this study optical coherence tomography (OCT) combined with a skin detector was used to monitor the response of second-degree scalded skin tissue irradiated by a CO2 laser. The process of treatment of second-degree scalding was systematically studied from the perspective of tissue optics. The OCT signal intensity was stronger within the whole recovery period in the experimental group undergoing CO2 laser treatment, and the attenuation coefficient (μt) returned to its original value in a shorter time. The results help us to understand tissue injury in a second-degree scald and may help improve the standard treatment.

Preparation of graphite dispersed copper composite on copper plate with CO2 laser

Science.gov (United States)

Yokoyama, S.; Ishikawa, Y.; Muizz, M. N. A.; Hisyamudin, M. N. N.; Nishiyama, K.; Sasano, J.; Izaki, M.

2018-01-01

It was tried in this work to prepare the graphite dispersed copper composite locally on a copper plate with a CO2 laser. The objectives of this study were to clear whether copper graphite composite was prepared on a copper plate and how the composite was prepared. The carbon content at the laser spot decreased with the laser irradiation time. This mainly resulted from the elimination by the laser trapping. The carbon content at the outside of the laser spot increased with time. Both the laser ablation and the laser trapping did not act on the graphite particles at the outside of the laser spot. Because the copper at the outside of the laser spot melted by the heat conduction from the laser spot, the particles were fixed by the wetting. However, the graphite particles were half-floated on the copper plate. The Vickers hardness decreased with an increase with laser irradiation time because of annealing.

Potential of sub-ablative pulsed CO2 laser irradiation on inhibition of artificial caries-like lesion progress in bovine dental enamel

International Nuclear Information System (INIS)

Oliveira, Marcella Esteves

2005-01-01

The aim of this study was to investigate whether sub-ablative pulsed C0 2 laser (1 0,6 μm) irradiation is capable of reducing the susceptibility of the dental enamel to demineralization, and thus achieving a potential caries-protective effect. The crowns of 51 bovine front teeth, embedded in acrylic resin and polished until exposure of flat enamel surface, were used. The samples were cut in cubes of 10x10 mm, and totally coated with acid-resistant nail varnish, except for an enamel exposed window of 16 mm square. Three groups (n=17) were obtained: control group (CG) not irradiated; group laser A (LA) and group laser B (LB) where the samples were irradiated. The conditions were 60 mJ, 100 Hz, 0,3 J/cm 2 for LA and 135 mJ, 10 Hz, 0,7 J/cm 2 for LB. Two samples of each group were submitted to SEM analysis and fifteen to demineralization in 3 ml acetate buffer solution (0,1 mol/L) with pH 4,5 for 24h at 37 deg C, with regular agitation. After the specimens were removed from the solution, the calcium and phosphorous content were measured with an inductively coupled plasma optical emission spectrometer and 2 more samples of each were submitted to SEM analysis. The obtained Ca and P means in μg/ml and the calculated Ca/P molar ratio were: CG (367,88 ± 33,47; 168,91 ± 14,55; 1,70 ± 0,07) ; LA (372,70 ± 41,70; 161,46 ± 15,26; 1,79 ± 0,07) and LB (328,87 ± 24,91; 145,02 ± 11,04; 1,77 ± 0,05). The ANOVA statistical test revealed statistically significant difference for [Ca], [P] e Ca/P content between the groups (p 2 pulsed CO 2 laser irradiation of bovine enamel was capable of reducing the enamel acid solubility without causing damage to the surface and therefore is a potential method of caries prevention. (author)

Ablation threshold and ablation mechanism transition of polyoxymethylene irradiated by CO2 laser.

Science.gov (United States)

Li, Gan; Cheng, Mousen; Li, Xiaokang

2016-09-01

Polyoxymethylene (POM) decomposes gradually as it is heated up by the irradiation of CO2 laser; the long-chain molecules of POM are broken into short chains, which leads to the lowering of the melting point and the critical temperature of the ablation products. When the product temperature is above the melting point, ablation comes up in the way of vaporization; when the product temperature is higher than the critical temperature, all liquid products are transformed into gas instantly and the ablation mechanism is changed. The laser fluence at which significant ablation is observed is defined as the ablation threshold, and the fluence corresponding to the ablation mechanism changing is denoted as the flyover threshold. In this paper, random pyrolysis is adopted to describe the pyrolytic decomposition of POM, and consequently, the components of the pyrolysis products under different pyrolysis rates are acquired. The Group Contribution method is used to count the thermodynamic properties of the pyrolysis products, and the melting point and the critical temperature of the product mixture are obtained by the Mixing Law. The Knudsen layer relationship is employed to evaluate the ablation mass removal when the product temperature is below the critical temperature. The gas dynamics conservation laws associated with the Jouguet condition are used to calculate the mass removal when the product temperature is higher than the critical temperature. Based on the model, a set of simulations for various laser intensities and lengths are carried out to generalize the relationships between the thresholds and the laser parameters. Besides the ablated mass areal density, which fits the experimental data quite well, the ablation temperature, pyrolysis rate, and product components are also discussed for a better understanding of the ablation mechanism of POM.

Study of XUV lasers produced by a CO/sub 2/ laser

International Nuclear Information System (INIS)

Daido, H.; Miura, E.; Kitagawa, Y.; Kato, Y.; Nishihara, K.; Sawai, K.; Nakai, S.S.; Yamanaka, C.

1988-01-01

The authors present recent progress at ILE, Osaka University in plasma recombination-pumped XUV lasers produced by a CO/sub 2/ laser. One way to produce large-population inversion with this scheme is rapid cooling of the gain medium keeping a high electron density, because the three-body recombination probability is proportional to the square of the electron density. The authors used a cylinder-type target made of 30-μm thick parylene (C/sub 8/H/sub 8/) whose diameter and length are 3 and 4 mm. The laser irradiated the 2500-A thick parylene foil attached to the center of the cylinder. The fully ablated plasma expands isotropically, producing an almost uniform plasma on the cylinder wall. Then the almost fully ionized carbon plasma is cooled by heat transport from the hot plasma to the wall. The estimated cooling time is a few nanoseconds assuming classical heat transport

Laser-induced short- and long-range orderings of Co nanoparticles on SiO2

International Nuclear Information System (INIS)

Favazza, C.; Trice, J.; Krishna, H.; Kalyanaraman, R.; Sureshkumar, R.

2006-01-01

Laser irradiation of ultrathin Co films leads to pattern formation by dewetting with short-range order (SRO) as well as long-range order (LRO). When a 1.5 nm thick Co film is irradiated by a single laser beam, a monomodal size distribution of particles with average diameter of 31±10 nm and nearest-neighbor spacing of 75 nm is observed. Moreover, melting by two-beam interference irradiation produces LRO as well as SRO giving a quasi-two-dimensional arrangement of nanoparticles. The SRO is attributed to spinodal dewetting while the LRO is conjectured to be induced by in-plane interfacial tension gradients. Laser-induced dewetting of metals could be a simple technique to fabricate ordered metal nanoarrays

Emerging terawatt picosecond CO2 laser technology

International Nuclear Information System (INIS)

Pogorelsky, I.V.

1997-09-01

The first terawatt picosecond (TWps) CO 2 laser is under construction at the BNL Accelerator Test Facility (ATF). TWps-CO 2 lasers, having an order of magnitude longer wavelength than the well-known table-top terawatt solid state lasers, offer new opportunities for strong-field physics research. For laser wakefield accelerators (LWFA) the advantage of the new class of lasers is due to a gain of two orders of magnitude in the ponderomotive potential. The large average power of CO 2 lasers is important for the generation of hard radiation through Compton back-scattering of the laser off energetic electron beams. The authors discuss applications of TWps-CO 2 lasers for LWFA modules of a tentative electron-positron collider, for γ-γ (or γ-lepton) colliders, for a possible table-top source of high-intensity x-rays and gamma rays, and the generation of polarized positron beams

Effects of Nd:YAG and CO2 lasers on cerebral microvasculature. Study in normal rabbit brain.

Science.gov (United States)

Kuroiwa, T; Tsuyumu, M; Takei, H; Inaba, Y

1986-01-01

The effect of Nd:YAG and CO2 laser beams on cerebral microvasculature was examined in experimental animals. Soft x-ray microangiography and histological examination of the brain after Nd:YAG laser exposure revealed broad avascular or oligovascular zones in the irradiated and the surrounding edematous tissue, in which the surviving vessels were narrowed and tapered without significant leakage of blood. After CO2 laser exposure, a wedge-shaped tissue defect surrounded by layers of charring, coagulation, and edema was observed. The main finding in the surrounding coagulation and edematous layers was dilatation of the vessels. Hemorrhage was sometimes observed, mainly in the edematous layer. These findings seem to explain the effective hemostatic capability of the Nd:YAG laser and the occasional hemorrhage following CO2 laser exposure, especially at high energy output.

High speed surface cleaning by a high repetition rated TEA-CO2 laser

International Nuclear Information System (INIS)

Tsunemi, Akira; Hirai, Ryo; Hagiwara, Kouji; Nagasaka, Keigo; Tashiro, Hideo

1994-01-01

We demonstrated the feasibility of high speed cleaning of solid surfaces by the laser ablation technique using a TEA-CO 2 laser. The laser pulses with the repetition rate of 1 kHz were applied to paint, rust, moss and dirt attached on the surfaces. The attachments were effectively removed without the damage of bulk surfaces by the irradiation of line-focused sequential pulses with an energy of 300 mJ/pulse. A cleaning rate reached to 17 m 2 /hour for the case of paint removal from iron surfaces. (author)

Thoracoscopic CO laser coagulation shrinkage of blebs in treatment of spontaneous pneumothorax

Science.gov (United States)

Sensaki, Koji; Arai, Tsunenori; Kikuchi, Keiichi; Takagi, Keigo; Tanaka, Susumu; Kikuchi, Makoto

1992-06-01

Spontaneous pneumothorax is a common disease in young people. Operative intervention has been done in most of the recurrent cases. Recently thoracoscopic treatment has been tested as a less invasive treatment modarity. We adopted carbon monoxide (CO) laser for thoracoscopic treatment of recurrent spontaneous pneumothorax. CO laser (wavelength; 5.4 micrometers ) could be delivered by chalcogenide glass (As - S) covered with a teflon sheath and ZnSe fiber tip. The sterilized flexible bronchoscope was inserted through the thoracoscopic outer sheath under local anesthesia. Shrinkage of blebs was obtained by non-contact method of CO laser irradiation. Laser power at the tip was 2.5 - 5 W and irradiation duration was 0.5 s each. Excellent shrinkage of bleb and bulla could be obtained by CO laser without perforation complication. Advantages of CO laser as a thoracoscopic treatment were: (1) capability of fiber delivery (flexible thoracoscopy was easy to operate and clear to visualize the blebs which were frequently found at the apical portion of the lung, and (2) shallow extinction length (good shrinkage of blebs, low risk of perforation, and thin layer of carbonization). In conclusion, our new technique of thoracoscopic CO laser irradiation was found to be a safe and effective treatment of spontaneous pneumothorax.

Laser Doppler velocimetry based on the optoacoustic effect in a RF-excited CO{sub 2} laser

Energy Technology Data Exchange (ETDEWEB)

Lee, Teaghee; Choi, Jong Woon [Department of Information and Communication, Honam University, Seobong-dong 59-1, Gwansan-gu, Gwangju 506-714 (Korea, Republic of); Kim, Yong Pyung [College of Electronics and Information, Kyunghee University, 1 Seocheon-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of)

2012-09-15

We present a compact optoacoustic laser Doppler velocimetry method that utilizes the self-mixing effect in a RF-excited CO{sub 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.

D2O laser pumped by an injection-locked CO2 laser for ion-temperature measurements

International Nuclear Information System (INIS)

Okada, Tatsuo; Ohga, Tetsuaki; Yokoo, Masakazu; Muraoka, Katsunori; Akazaki, Masanori.

1986-01-01

The cooperative Thomson scattering method is one of the various new techniques proposed for measuring the temperature of ions in nuclear fusion critical plasma, for which a high-performance FIR laser pumped by an injection-locked CO 2 laser is required. This report deals with D 2 O laser with a wavelength of 385 μm which is pumped by injection-locked single-mole TEA CO 2 laser composed of a driver laser and an output-stage laser. A small-sized automatic pre-ionization type laser is employed for the driver. The resonator of the driver laser consists of a plane grating of littrow arrangement and ZnSe plane output mirrors with reflection factor of 50 %. An aperture and ZnSe etalon are inserted in the resonator to produce single transverse- and longitudinal-mode oscillation, respectively. The output-stage laser is also of the automatic pre-ionization type. Theoretically, an injection power of 0.1 pW/mm 3 is required for a CO 2 laser. Single-mode oscillation of several hundred nW/mm 3 can be produced by the CO 2 laser used in this study. Tuning of the output-stage laser is easily controlled by the driver laser. High stability of the injection-locked operation is demonstrated. CO 2 laser beam is introduced into the D 2 O laser through a KCl window to excite D 2 O laser beam in the axial direction. Input and output characteristics of the D 2 O laser are shown. Also presented are typical pulse shapes from the D 2 O laser pumped by a free-running CO 2 laser pulse or by an injection-locked single-mode CO 2 laser pulse. (Nogami, K.)

Effect of LASER Irradiation on the Shear Bond Strength of Zirconia Ceramic Surface to Dentin

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Sima Shahabi

2012-09-01

Full Text Available Background and Aims: Reliable bonding between tooth substrate and zirconia-based ceramic restorations is always of great importance. The laser might be useful for treatment of ceramic surfaces. The aim of the present study was to investigate the effect of laser irradiation on the shear bond strength of zirconia ceramic surface to dentin. Materials and Methods: In this experimental in vitro study, 40 Cercon zirconia ceramic blocks were fabricated. The surface treatment was performed using sandblasting with 50-micrometer Al2O3, CO2 laser, or Nd:YAG laser in each test groups. After that, the specimens were cemented to human dentin with resin cement. The shear bond strength of ceramics to dentin was determined and failure mode of each specimen was analyzed by stereo-microscope and SEM investigations. The data were statistically analyzed by one-way analysis of variance and Tukey multiple comparisons. The surface morphology of one specimen from each group was investigated under SEM. Results: The mean shear bond strength of zirconia ceramic to dentin was 7.79±3.03, 9.85±4.69, 14.92±4.48 MPa for CO2 irradiated, Nd:YAG irradiated, and sandblasted specimens, respectively. Significant differences were noted between CO2 (P=0.001 and Nd:YAG laser (P=0.017 irradiated specimens with sandblasted specimens. No significant differences were observed between two laser methods (P=0.47. The mode of bond failure was predominantly adhesive in test groups (CO2 irradiated specimens: 75%, Nd:YAG irradiated: 66.7%, and sandblasting: 41.7%. Conclusion: Under the limitations of the present study, surface treatment of zirconia ceramics using CO2 and Nd:YAG lasers was not able to produce adequate bond strength with dentin surfaces in comparison to sandblasting technique. Therefore, the use of lasers with the mentioned parameters may not be recommended for the surface treatment of Cercon ceramics.

Electron microscopy of CO/sub 2/-laser-induced effects in human fibrocartilage

Energy Technology Data Exchange (ETDEWEB)

Whipple, T.L.; Marotta, J.J.; May, T.C.; Caspari, R.B.; Meyers, J.F.

1987-01-01

Previous reports of effects of CO/sub 2/ laser energy on human fibrocartilage suggest thermal injury extends to a depth of approximately 70 microns from the target surface with power settings of 35 W and exposure times of 0.5 seconds. The present study was undertaken to look for more subtle evidence of thermal alteration of human fibrocartilage treated with CO/sub 2/ laser irradiation. Fifteen human menisci were irradiated at power settings of 10, 20, and 30 W with exposure times of 0.1 and 0.5 seconds. The specimens were immediately fixed and sectioned for electron microscopic examination. Loss of a normal cross banding, and marginal clarity of individual collagen fibers were observed in the extracellular matrix and were observed at distances up to 300 microns from the exposed tissue surface. In addition, cellular changes at similar tissue depth consisted of cell membrane invaginations, clumping of nuclear chromatin, breakdown of endoplasmic reticulum architecture, and loss of mitochondria and Golgi complexes from the cytoplasm were observed. This study demonstrates deeper penetration of a radiation that was previously appreciated by light microscopy in irradiated human fibrocartilage, although the implications with respect to contraside viability and healing potential of the tissue in vivo is not known.

Development of high power pulsed CO2 laser

International Nuclear Information System (INIS)

Nakai, Sadao; Matoba, Masafumi; Fujita, Hisanori; Daido, Hiroyuki; Inoue, Mitsuo

1982-01-01

The inertial nuclear fusion research using pellet implosion has rapidly progressed accompanying laser technique improvement and output increase. As the high output lasers for this purpose, Nd glass lasers or CO 2 lasers are used. The CO 2 lasers possess the characteristics required as reactor lasers, i.e., high efficiency, high frequency repetition, possibility of scale-up and economy. So, the technical development of high power CO 2 lasers assuming also as reactor drivers has been performed at a quick pace together with the research on the improvement of efficiency of pellet implosion by 10 μm laser beam. The Institute of Laser Engineering, Osaka University, stated to build a laser system LEKKO No. 8 of 8 beams and 10 kJ based on the experiences in laser systems LEKKO No. 1 and LEKKO No. 2, and the system LEKKO No. 8 was completed in March, 1981. The operation tests for one year since then has indicated as the laser characteristics that the system performance was as designed initially. This paper reviews the structure, problems and present status of the large scale CO 2 lasers. In other words, the construction of laser system, CO 2 laser proper, oscillator, booster amplifier, prevention of parasitic oscillation, non-linear pulse propagation and fairing of output pulse form, system control and beam alignment, and high power problems are described. The results obtained are to be reported in subsequent issues. (Wakatsuki, Y.)

CO2 laser technology for advanced particle accelerators

International Nuclear Information System (INIS)

Pogorelsky, I.V.

1996-06-01

Short-pulse, high-power CO 2 lasers open new prospects for development of ultra-high gradient laser-driven electron accelerators. The advantages of λ=10 μm CO 2 laser radiation over the more widely exploited solid state lasers with λ∼1 μm are based on a λ 2 -proportional ponderomotive potential, λ-proportional phase slippage, and λ-proportional scaling of the laser accelerator structures. We show how a picosecond terawatt CO 2 laser that is under construction at the Brookhaven Accelerator Test Facility may benefit the ATF's experimental program of testing far-field, near-field, and plasma accelerator schemes

Effects of He-Ne laser irradiation on red blood cells in vitro

Science.gov (United States)

Ghadage, Vijay H.; Kulkarni, Gauri R.

2011-03-01

Laser radiation has many applications in biomedical field, such as wound healing, tissue repairing, heating and ablation processes. Intravenous low power laser radiation is used clinically for skin and vascular disorders. Laser radiation improves microcirculation and modulates the rheological properties of blood. FTIR (Fourier Transform Infra Red Spectra) is used to see the structural changes in erythrocyte membrane. In the present work He Ne laser (λ= 632nm, power=2mW) is used to irradiate human Red blood cells. Red blood cells are separated from human whole blood using centrifugation method (time=10 min., temperature=15°C and RPM=3000) and then exposed to HeNe laser radiation. Laser exposure time is varied from 10 min. to 40min for Red blood cells. Absorption spectrum, FTIR and fluorescence spectra of RBC are compared before and after HeNe laser irradiation. The absorption spectrum of RBC after exposure to HeNe laser shows a significant decrease in absorbance. The FTIR spectrum of non irradiated RBC clearly show the peaks due to O-H (free group), C=O (amide I group), N=O (nitro group), C-O (anhydride group) and C-H (aromatic group). Laser radiation changes in transmittance in FTIR spectra related to C=O group and percentage of transmittance increases for O-H, C=C, N=O, C-O and C-H group.

CO2 laser direct writing of silver lines on epoxy resin from solid film

International Nuclear Information System (INIS)

Liu, J.G.; Chen, C.H.; Zheng, J.S.; Huang, J.Y.

2005-01-01

A technique of CO 2 laser direct writing from solid film was proposed in this paper. Patterns of silver lines were locally deposited on the non-conductive substrate using a preset layer of silver compound solid film, which was irradiated by focused CO 2 laser beam. The deposits were analyzed by XPS and EPMA. Results showed that metallic silver was dominant with an even distribution on the surface of the substrate, and part of the deposited silver had diffused into the substrate interior. The deposits had catalytic activity for the further electroless copper plating and had strong adhesion to the substrate. At last, the deposition mechanism and the dependence of the width of silver lines on the laser power and scan speed were roughly explored

Emerging terawatt picosecond CO{sub 2} laser technology

Energy Technology Data Exchange (ETDEWEB)

Pogorelsky, I V [Accelerator Test Facility, Brookhaven National Lab., Upton, NY (United States)

1998-03-01

The first terawatt picosecond (TWps) CO{sub 2} laser is under construction at the BNL Accelerator Test Facility (ATF). TWps-CO{sub 2} lasers, having an order of magnitude longer wavelength than the well-known table-top terawatt solid state lasers, offer new opportunities for strong-field physics research. For laser wakefield accelerators (LWFA) the advantage of the new class of lasers is due to a gain of two orders of magnitude in the ponderomotive potential. The large average power of CO{sub 2} lasers is important for the generation of hard radiation through Compton back-scattering of the laser off energetic electron beams. We discuss applications of TWps-CO{sub 2} lasers for LWFA modules of a tentative electron-positron collider, for {gamma}-{gamma} (or {gamma}-lepton) colliders, for a possible `table-top` source of high-intensity x-rays and gamma rays, and the generation of polarized positron beams. (author)

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

Lithium niobate bulk crystallization promoted by CO{sub 2} laser radiation

Energy Technology Data Exchange (ETDEWEB)

Ferreira, N.M., E-mail: nmferreira@ua.pt [i3N - Aveiro, Physics Department, Aveiro University, Campus Universitario de Santiago, 3810-193 Aveiro (Portugal); Costa, F.M. [i3N - Aveiro, Physics Department, Aveiro University, Campus Universitario de Santiago, 3810-193 Aveiro (Portugal); Nogueira, R.N. [Instituto de Telecomunicacoes, 3810-193 Aveiro (Portugal); Graca, M.P.F. [i3N - Aveiro, Physics Department, Aveiro University, Campus Universitario de Santiago, 3810-193 Aveiro (Portugal)

2012-09-15

Highlights: Black-Right-Pointing-Pointer Crystallization of LiNbO{sub 3} nanocrystals in a SiO{sub 2} matrix by CO{sub 2} laser irradiation process. Black-Right-Pointing-Pointer Samples heat-treated at 650 Degree-Sign C (4 h) and laser treated (4 W/500 s) show similar morphology. Black-Right-Pointing-Pointer Glass-ceramics produced by laser process requires a very low processing time. - Abstract: The crystallization induced by laser radiation is a very promising technique to promote glass/ceramic transformation, being already used to produce crystalline patterns on glass surfaces. In this work, a SiO{sub 2}-Li{sub 2}O-Nb{sub 2}O{sub 5} glass, prepared by the sol-gel route, was submitted to CO{sub 2} laser radiation and conventional heat-treatments in order to induce the LiNbO{sub 3} crystallization. The structure and morphology of the samples prepared by both routes was analyzed as a function of exposure time, radiation power and heat-treatment temperatures by XRD, Raman spectroscopy and SEM. The results reveal a correlation between the crystallization degree of LiNbO{sub 3} particles and glass matrix with the heat treatment type and experimental parameters. An heat-treatment at 650 Degree-Sign C/4 h was necessary to induce crystallization in heat treatments samples while 4 W/500 s was enough for laser radiation ones, corresponding a reduction time processing of {approx}14 000 s.

Electron acceleration by CO/sub 2/ laser

International Nuclear Information System (INIS)

Fujita, H.; Kitagawa, Y.; Daido, H.

1986-01-01

Experiments on electron acceleration have been performed by LEKKO VIII CO/sub 2/ laser system. The laser light was focused by an off-axis parabolic mirror with the F-number of 1.5 and irradiated to thin foil and pipe targets in order to obtain uniform underdense plasmas. Energy spectrum of electrons was measured by an electron spectrometer in the range of 0.3-1.1 MeV. In the single frequency case, electrons up to 1 MeV were observed in the direction of the laser axis for the laser intensity above 1.6 x 10/sup 14/ W/cm/sup 2/ which was equal to the estimated threshold for forward Raman scattering. Amount of high energy electrons depended on the interaction length and the background hot electron temperature. More electrons could resonate with the plasma wave for the higher hot electron temperature. This was confirmed by particle simulation. In most experiments, the plasma density was estimated of about 0.1 n/sub c/. When the plasma density was reduced to 0.01 n/sub c/ using pre-pulse, high energy electrons were not observed because of the low background hot electron temperature and the higher instability threshold. In the two frequency case, energetic electron beam injection is planned for efficient coupling with fast plasma wave. Pipe target seems to be hopeful because 1) the laser light is confined by the plasma fiber and 2) the phase velocity of the plasma wave is controlled by the transverse mode

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.

Picosecond CO2 laser for relativistic particle acceleration

International Nuclear Information System (INIS)

Pogorelsky, I.; Ben-Zvi, I.; Kimura, W.D.; Kurnit, N.A.; Kannari, F.

1994-01-01

A table-top 20-GW 50-ps CO 2 laser system is under operation at the Brookhaven Accelerator Test Facility. We compare laser performance with model predictions. Extrapolations suggest the possibility of compact terawatt CO 2 laser systems suitable as laser accelerator drivers and for other strong-field applications. Latest progress on an Inverse Cherenkov Laser Accelerator experiment is reported

Plasma production and heating by a laser TEA-CO2

International Nuclear Information System (INIS)

Goes, L.C.S.; Sudano, J.P.; Rodrigues, N.A.S.

1987-01-01

Preliminary experiments of plasma production and heating by laser irradiation of gases and solid targets have been performed with a laser TEA-CO 2 (1 MW, 80 ns, monomode), developed and built at the IEAv/Laser Laboratory. The laser beam was focused in the interior of a vacuum chamber (100 1) with a base pressure of 10 1 torr, and recolimated by a system of confocal lenses. The breakdown theresholds for nitrogen gas was investigated by varying the laser power, the neutral gas density and the focal lenght of the lenses. Plasma breakdown observed in the range of pressures between 100-720 torr was in good agreement with calculations of cascade ionization theory and classical absorption by inverse-Bremsstrahlung. The laser absorption was inferred by measuring the power transmitted in the presence and absence of plasma. The light emitted by the plasma was detected by a fast photo-diode, indicating that the plasma expansion phase lasted for several microseconds. These investigations have been applied in the development of plasma shutters for laser pulse compression. (author) [pt

Development of high-power CO2 lasers and laser material processing

Science.gov (United States)

Nath, Ashish K.; Choudhary, Praveen; Kumar, Manoj; Kaul, R.

2000-02-01

Scaling laws to determine the physical dimensions of the active medium and optical resonator parameters for designing convective cooled CO2 lasers have been established. High power CW CO2 lasers upto 5 kW output power and a high repetition rate TEA CO2 laser of 500 Hz and 500 W average power incorporated with a novel scheme for uniform UV pre- ionization have been developed for material processing applications. Technical viability of laser processing of several engineering components, for example laser surface hardening of fine teeth of files, laser welding of martensitic steel shroud and titanium alloy under-strap of turbine, laser cladding of Ni super-alloy with stellite for refurbishing turbine blades were established using these lasers. Laser alloying of pre-placed SiC coating on different types of aluminum alloy, commercially pure titanium and Ti-6Al-4V alloy, and laser curing of thermosetting powder coating have been also studied. Development of these lasers and results of some of the processing studies are briefly presented here.

Physiological characteristics of cucumber seed production plants by presowing laser and gamma irradiation

International Nuclear Information System (INIS)

Cholakov, D.; Petkova, V.

1994-01-01

Seeds from G-3 maternal line of hybrid cucumber cultivar Pobeda F 1 were treated with helium-neon 632.8 nm laser-exit power 20 mW and gamma-rays ( 60 Co) in a field experiment under conditions suitable for hybrid seed production. The irradiation was carried out a week before sowing and the following variants were investigated: 1. sevenfold laser irradiation; 2. 10 Gy gamma irradiation; 3. combined laser + gamma rays irradiation. Seeds from the parent line were not irradiated. A positive effect of irradiation on the photosynthetic intensity, content of plastid pigments in leaves and activity of catalase and peroxidase has been observed. (author)

The effect of CO2 laser irradiation plus fluoride dentifrice on the inhibition of secondary caries on root surfaces adjacent to glass ionomer cement or composite resin restorations

International Nuclear Information System (INIS)

Rodrigues, S R; Moraes, M; Youssef, M N; De Souza-Zaroni, W C; Hanashiro, F S; Brugnera Junior, A; Nobre-dos-Santos, M

2016-01-01

Although the cariostatic effects of CO 2 laser on the root surface have been shown, there is scarce information regarding its effects on root secondary caries. The objective of this research was to investigate the effect of the association of CO 2 laser and a fluoride dentifrice on the inhibition of secondary caries on root surfaces adjacent to composite-resin or glass-ionomer-cement restorations. Dental blocks of human roots were divided into two groups: composite resin (CR) or glass ionomer cement (GIC). Subsequently, the blocks were divided into four subgroups (n  =  10): C, non-fluoride dentifrice; FD, fluoride dentifrice; L, CO 2 laser with an energy density of 6.0 J cm −2   +  non-fluoride dentifrice; and L  +  FD, CO 2 laser  +  fluoride dentifrice. The blocks were subjected to pH cycling to simulate a high cariogenic challenge. Dental demineralization around the restorations was quantified by microhardness analysis. The results were subjected to analysis of variance (ANOVA) and the Tukey–Kramer test (p  ⩽  0.05). As for mineral loss, it can be observed that all the groups that were treated with a fluoride dentifrice and laser, used alone or not, were statistically similar and superior to the RC–C group. It was concluded that CO 2 laser irradiation and a fluoride dentifrice used alone or combined with each other are efficient surface treatments for preventing secondary root caries, regardless of the restorative material used. (paper)

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.

Effect of CO2 laser on root caries inhibition around composite restorations: an in vitro study.

Science.gov (United States)

de Melo, Jociana Bandeira; Hanashiro, Fernando Seishim; Steagall, Washington; Turbino, Miriam Lacalle; Nobre-dos-Santos, Marinês; Youssef, Michel Nicolau; de Souza-Zaroni, Wanessa Christine

2014-03-01

The aim of the present study was to investigate the in vitro effect of CO2 laser on the inhibition of root surface demineralization around composite resin restorations. For this purpose, 30 blocks obtained from human molar roots were divided into three groups: group 1 (negative control), cavity prepared with cylindrical diamond bur + acid etching + adhesive + composite resin restoration; group 2, cavity prepared with cylindrical diamond bur + CO2 laser (5.0 J/cm(2)) + acid etching + adhesive + composite resin; and group 3, cavity prepared with cylindrical diamond bur + CO2 laser (6.0 J/cm(2)) + acid etching + adhesive + composite resin. After this procedure, the blocks were submitted to thermal and pH cycling. Root surface demineralization around the restorations was measured by microhardness analysis. The hardness results of the longitudinally sectioned root surface were converted into percentage of mineral volume, which was used to calculate the mineral loss delta Z (ΔZ). The percentage of mineral volume, ΔZ, and the percentage of demineralization inhibition of the groups were statistically analyzed by using analysis of variance and Tukey-Kramer test. The percentage of mineral volume was higher in the irradiated groups up to 80 μm deep. The ΔZ was significantly lower in the irradiated groups than in the control group. The percentage of reduction in demineralization ranged from 19.73 to 29.21 in position 1 (50 μm), and from 24.76 to 26.73 in position 2 (100 μm), when using 6 and 5 J/cm(2), respectively. The CO2 laser was effective in inhibiting root demineralization around composite resin restorations.

In vitro evaluation of the morphologic changes on the root dentine irradiated by CO{sub 2} laser associated or not to calcium hydroxide application; Avaliacao in vitro das alteracoes morfologicas da superficie da dentina radicular irradiada pelo laser de CO{sub 2} associado ou nao a aplicacao de hidroxido de calcio

Energy Technology Data Exchange (ETDEWEB)

Romano, Ana Cristina Cury Camargo

2003-07-01

This in vitro study has evaluated the structural changes on the root dentine irradiated by a CO{sub 2} laser associated or not to calcium hydroxide application, from the irradiated surface analysis by means of Scanning Electronic Microscopy (SEM). The purpose of this evaluation has been the study of an alternative method for the treatment of dentine hypersensitivity. Fourteen human teeth were utilized, third molars, divided into 7 groups. Group I (control group) to which no treatment was applied; Groups II, III and IV were given an application of Ca (OH){sub 2} paste followed by C0{sub 2} laser irradiation, lasting 5 seconds each with intervals of 10 seconds between each application, with continuous emission, power of 0.5 W (Group II), 1.0 W (Group III), and 1.5 W (Group IV); Groups V, VI, and VII were given laser irradiations without the Ca (OH){sub 2} paste following the same parameters applied to groups II, III, and IV respectively. Morphologic changes suggesting to fusion and re-solidification have been observed, as well as the presence of material obstructing the whole analyzed surface on groups II, III, and IV (laser + Ca (OH){sub 2}). As for groups V, VI, and VII, it has been observed fusion, re-solidification, and cracks, and these results being statistically significant when compared the '(Ca (OH){sub 2})' groups to the laser groups. No statistically significant differences were observed regarding the different powers applied in the groups that used the same treatment. Despite this result, it can be stated that powers above 1.0 W (DP = 125,38 W/cm{sup 2}) are unfavorable due to the undesirable morphologic alterations and aesthetic compromising. (author)

In vitro evaluation of the morphologic changes on the root dentine irradiated by CO{sub 2} laser associated or not to calcium hydroxide application; Avaliacao in vitro das alteracoes morfologicas da superficie da dentina radicular irradiada pelo laser de CO{sub 2} associado ou nao a aplicacao de hidroxido de calcio

Energy Technology Data Exchange (ETDEWEB)

Romano, Ana Cristina Cury Camargo

2003-07-01

This in vitro study has evaluated the structural changes on the root dentine irradiated by a CO{sub 2} laser associated or not to calcium hydroxide application, from the irradiated surface analysis by means of Scanning Electronic Microscopy (SEM). The purpose of this evaluation has been the study of an alternative method for the treatment of dentine hypersensitivity. Fourteen human teeth were utilized, third molars, divided into 7 groups. Group I (control group) to which no treatment was applied; Groups II, III and IV were given an application of Ca (OH){sub 2} paste followed by C0{sub 2} laser irradiation, lasting 5 seconds each with intervals of 10 seconds between each application, with continuous emission, power of 0.5 W (Group II), 1.0 W (Group III), and 1.5 W (Group IV); Groups V, VI, and VII were given laser irradiations without the Ca (OH){sub 2} paste following the same parameters applied to groups II, III, and IV respectively. Morphologic changes suggesting to fusion and re-solidification have been observed, as well as the presence of material obstructing the whole analyzed surface on groups II, III, and IV (laser + Ca (OH){sub 2}). As for groups V, VI, and VII, it has been observed fusion, re-solidification, and cracks, and these results being statistically significant when compared the '(Ca (OH){sub 2})' groups to the laser groups. No statistically significant differences were observed regarding the different powers applied in the groups that used the same treatment. Despite this result, it can be stated that powers above 1.0 W (DP = 125,38 W/cm{sup 2}) are unfavorable due to the undesirable morphologic alterations and aesthetic compromising. (author)

Yeast cell metabolism investigated by CO{_2} production and soft X-ray irradiation

Science.gov (United States)

Masini, A.; Batani, D.; Previdi, F.; Milani, M.; Pozzi, A.; Turcu, E.; Huntington, S.; Takeyasu, H.

1999-01-01

Results obtained using a new technique for studying cell metabolism are presented. The technique, consisting in CO2 production monitoring, has been applied to Saccharomyces cerevisiae yeast cells. Also the cells were irradiated using the soft X-ray laser-plasma source at Rutherford Appleton Laboratory with the aim of producing a damage of metabolic processes at the wall level, responsible for fermentation, without great interference with respiration, taking place in mitochondria, and DNA activity. The source was calibrated with PIN diodes and X-ray spectrometers and used Teflon stripes as target, emitting X-rays at about 0.9 keV, with a very low penetration in biological material. X-ray doses delivered to the different cell compartments were calculated following a Lambert-Bouguet-Beer law. Immediately after irradiation, the damage to metabolic activity was measured again by monitoring CO2 production. Results showed a general reduction in gas production by irradiated samples, together with non-linear and non-monotone response to dose. There was also evidence of oscillations in cell metabolic activity and of X-ray induced changes in oscillation frequency.

CO2 laser technology for advanced particle accelerators. Revision

International Nuclear Information System (INIS)

Pogorelsky, I.V.

1996-06-01

Short-pulse, high-power CO 2 lasers open new prospects for development of ultra-high gradient laser-driven electron accelerators. The advantages of λ=10 μm CO 2 laser radiation over the more widely exploited solid state lasers with λ∼1 μm are based on a λ 2 -proportional ponderomotive potential, λ-proportional phase slippage distance, and λ-proportional scaling of the laser accelerator structures. We show how a picosecond terawatt CO 2 laser that is under construction at the Brookhaven Accelerator Test Facility may benefit the ATF's experimental program of testing far-field, near-field, and plasma accelerator schemes

Synchronisation of electron-beam controlled CO2 lasers with a plasma mirror

International Nuclear Information System (INIS)

Basov, N.G.; Boiko, V.A.; Danilychev, V.A.; Zvorykin, V.D.; Lobanov, A.N.; Kholin, I.V.; Chugunov, A.Y.

1979-03-01

A new approach to the development of laser systems for spherically symmetrical compression of thermonuclear targets which essentially involves using a plasma formed by the action of laser radiation on the surface of a target as a common mirror for high-power electron-beam-controlled CO 2 lasers distributed uniformly around a sphere has been proposed. The achievement of the required time-synchronised operation of several lasers to obtain symmetrical irradiation is discussed here. It is found that the lasers cannot be synchronised accurately by stabilising only the electrical parameters of the systems. Even if the laser pumping systems are switched on strictly simultaneously, small random fluctuations in the pumping level, active mixture composition, optical Q factor of the resonators and other parameters give rise to an appreciable scatter in the output pulse evolution times. Methods for precise synchronisation based on introducing optical coupling between the laser resonators are proposed. (UK)

Stereotactic CO2 laser therapy for hydrocephalus

Science.gov (United States)

Kozodoy-Pins, Rebecca L.; Harrington, James A.; Zazanis, George A.; Nosko, Michael G.; Lehman, Richard M.

1994-05-01

A new fiber-optic delivery system for CO2 radiation has been used to successfully treat non-communicating hydrocephalus. This system consists of a hollow sapphire waveguide employed in the lumen of a stereotactically-guided neuroendoscope. CO2 gas flows through the bore of the hollow waveguide, creating a path for the laser beam through the cerebrospinal fluid (CSF). This delivery system has the advantages of both visualization and guided CO2 laser radiation without the same 4.3 mm diameter scope. Several patients with hydrocephalus were treated with this new system. The laser was used to create a passage in the floor of the ventricle to allow the flow of CSF from the ventricles to the sub-arachnoid space. Initial postoperative results demonstrated a relief of the clinical symptoms. Long-term results will indicate if this type of therapy will be superior to the use of implanted silicone shunts. Since CO2 laser radiation at 10.6 micrometers is strongly absorbed by the water in tissue and CSF, damage to tissue surrounding the lesion with each laser pulse is limited. The accuracy and safety of this technique may prove it to be an advantageous therapy for obstructive hydrocephalus.

Investigation of scleral buckling by CO2 laser

International Nuclear Information System (INIS)

Maswadi, S.

2001-05-01

This thesis investigates the effect of using the infrared wavelength CO 2 laser (10.6μm) as a localised heat source for inducing scleral buckling on eyes. Retinal detachment disease is a major cause of blindness and the scleral buckling is an important technique used in treatment. A radio-frequency excited 10.6λm laser source is used to heat collagen in the sclera above its shrinkage temperature so as to produce a localised indentation and deformation in the human eye (in vitro). Basic measurements of the onset shrinkage temperatures of porcine and human sclera are taken. Optical properties of sclera tissue at 10.6μm are also determined to provide information about the interaction of the CO 2 laser with the sclera. It is found that CO 2 laser radiation is highly absorbed by the scleral water. Optical diffraction technique is investigated to quantify in-plane deformation in the sclera tissue as result of heating by producing grating on porcine and human sclera using the ArF laser (193nm). Photothermal deflection technique is also used to investigate scleral ablation by using the TEA and Ultrapulse CO 2 laser. This technique provides a useful guide to the regime where ablation rather than heat shrinkage of collagen in the sclera will dominate using the Ultrapulse CO 2 laser. A quantitative assessment of buckling using the technique of projection moire interferometry is described which allows a non-contact measurement to be made of the out-of-plane displacement by laser radiation. In-plane surface strain (shrinkage) has also been demonstrated using in-situ optical microscopy of the laser treated eye. The moire method is suitable to obtain information on buckling in real time and to obtain a three-dimensional view of the eye surface as laser treatment proceeds. A theoretical heat flow model is described for predicting the temperature profile produced in the sclera using the Ultrapulse CO 2 laser. For appropriate exposure parameters the CO 2 laser is found to be an

Pulse laser irradiation into superconducting MgB2 detector

International Nuclear Information System (INIS)

Fujiwara, Daisuke; Miki, Shigehito; Satoh, Kazuo; Yotsuya, Tsutomu; Shimakage, Hisashi; Wang, Zhen; Okayasu, Satoru; Katagiri, Masaki; Machida, Masahiko; Kato, Masaru; Ishida, Takekazu

2005-01-01

We performed 20-ps pulse laser irradiation experiments on a MgB 2 neutron detector to know a thermal-relaxation process for designing a MgB 2 neutron detector. The membrane-type structured MgB 2 device was fabricated to minimize the heat capacity of sensing part of a detector as well as to enhance its sensitivity. We successfully observed a thermal-relaxation signal resulting from pulse laser irradiation by developing a detection circuit. The response time was faster than 1 μs, meaning that the detector would be capable of counting neutrons at a rate of more than 10 6 events per second

Effect of maize seed laser irradiation on plant photosynthetic activity

International Nuclear Information System (INIS)

Antonov, M.; Stanev, V.; Velichkov, D.; Tsonev, Ts.

1986-01-01

Investigations were made with the two hybrids, H-708 and P x -20. The seeds were irradiated by a helium-neon quantum generator (L'vov-1 Electronica) with output power of 24 MW and 632.8 nm wave length. Once and twice irradiated seeds were sown on the 2nd, 5th and 10th day post irradiation. Changes in leaf area, chlorophyll content in the leaves, photosynthetic rate and its dependence on temperature and light, transpiration, stomatal resistance to CO 2 and total dry matter of the overground plant part were traced. Seed irradiation with laser rays did not affect the chlorophyll content of the leaves. The photosynthetic rate did not depend on the cultivar characteristics of the crop. Single and repeated irradiation of the hybrid H-708 in most case enhanced photosynthetic rate, but a similar effect was not observed in P x -20. Transpiration and CO 2 stomatal resistance were not equally affected by radiation. Laser rays enhanced the ability of the photosynthetic apparatus of the entire plants to use more efficiently high light intensities. The leaf area and the total plant dry matter increased in case of sowing on the 2nd and 5th day and a single irradiation and in case of sowing on the 5th and 10th day and twice repeated irradiations

Easy Debonding of Ceramic Brackets Bonded with a Light-Cured Orthodontic Adhesive Containing Microcapsules with a CO2 Laser.

Science.gov (United States)

Arima, Shiori; Namura, Yasuhiro; Tamura, Takahiko; Shimizu, Noriyoshi

2018-03-01

An easy debonding method for ceramic brackets using a light-cured Bis-GMA resin containing heat-expandable microcapsules and CO 2 laser was investigated. Ceramic brackets are used frequently in orthodontic treatment because of their desirable esthetic properties. However, the application of heavy force to ceramic brackets in debonding can fracture the tooth enamel and ceramic brackets, causing tooth pain. In total, 60 freshly extracted bovine permanent mandibular incisors were divided randomly into 10 groups of 6 specimens each, corresponding to the number of variables tested. Ceramic brackets were bonded to bovine permanent mandibular incisors using an orthodontic bonding agent containing heat-expandable microcapsules at different levels (0-30 wt%) and resin composite paste, and cured by a curing device. The bond strengths were measured before and after CO 2 laser irradiation, and the temperature increase in the pulp chamber in fresh human first premolars was also evaluated. With CO 2 laser irradiation for 5 sec to the bracket, the bond strength in the 25% microcapsule group decreased significantly, to ∼0.17-fold, compared with that of the no-laser group (p brackets, with less debonding time and enamel damage.

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...

Comparative study of etched enamel and dentin for the adhesion of composite resins with the Er:YAG 2,94 μm laser and CO2 9,6 μm laser: morphological (SEM) and tensile bond strength analysis

International Nuclear Information System (INIS)

Marraccini, Tarso Mugnai

2002-01-01

The aim of this study was to evaluate and compare the tensile bond strength of a composite resin adhered to the enamel and dentin which have received superficial irradiation with an Er:YAG laser (2.94 μm) or with CO 2 laser ( 9.6 μm) and later on etched with the phosphoric acid at 35%. After the use of the adhesive system, resin cones were made on the etched surfaces by both lasers and tensile bond strength tests were performed. All samples were observed at the SEM - there was an increase of the degree of fusion and resolidification in the irradiated enamel and dentin samples with the CO 2 laser (9.6 μm), creating a vitrified layer with tiny craters. With the Er:YAG laser (2.94 μm) there were typical morphological explosive microablation with the exposition of the tubules in the dentin.The surface acquired by the association of the CO 2 laser ( 9.6 μm) plus acid etching no longer presented the aspect of fusion being this layer completely removed. There were statistical significant differences among ali three methods of etching in the treatment of the enamel and dentin surface. The tensile bond strength test showed that etching of these enamel and dentin surfaces with acid exclusively (control group) presented great values, surpassing the values of the etching acquired with the Er:YAG laser (2.94 μ) plus acid or the CO 2 laser (9.6 μm) plus acid. With the parameters used in this experiment the Er:YAG laser (2.94 μm) showed to be more effective than the CO 2 laser (9.6 μm) for the hard dental surfaces etching procedure. (author)

CO2 laser photolysis of clustered ions, (1)

International Nuclear Information System (INIS)

Ikezoe, Yasumasa; Soga, Takeshi; Suzuki, Kazuya; Ohno, Shin-ichi.

1990-09-01

Vibrational excitation and the following decomposition of cluster ions by CO 2 laser photons are studied. Characteristics of the cluster ion and the CO 2 laser photon are summarized in their relation to the photolysis of cluster ions. An apparatus was installed, which is composed of (1) corona discharge-jet expansion section (formation of cluster ions), (2) CO 2 laser section (photolysis of cluster ions), and (3) mass spectrometer section. Experimental results of ammonia cluster ions were described. Effects of repeller voltage, shape of repellers, and adiabatic cooling are examined on the formation of ammonia cluster ions by corona discharge-jet expansion method. Collisional dissociation of cluster ions was observed at high repeller voltages. Size distribution of the ammonia cluster ion is discussed in connection with the temperature of cluster ions. Intensity of CO 2 laser was related to decomposition yield of cluster ions. (author)

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.

Comparative study of etched enamel and dentin for the adhesion of composite resins with the Er:YAG 2,94 {mu}m laser and CO{sub 2} 9,6 {mu}m laser: morphological (SEM) and tensile bond strength analysis; Estudo comparativo do condicionamento do esmalte e dentina para a adesao de resinas compostas com os lasers Er:YAG 2,94 {mu}m e com o laser CO{sub 2} de 9,6 {mu}m: analise morfologica e de resistencia a tracao

Energy Technology Data Exchange (ETDEWEB)

Marraccini, Tarso Mugnai

2002-07-01

The aim of this study was to evaluate and compare the tensile bond strength of a composite resin adhered to the enamel and dentin which have received superficial irradiation with an Er:YAG laser (2.94 {mu}m) or with CO{sub 2} laser ( 9.6 {mu}m) and later on etched with the phosphoric acid at 35%. After the use of the adhesive system, resin cones were made on the etched surfaces by both lasers and tensile bond strength tests were performed. All samples were observed at the SEM - there was an increase of the degree of fusion and resolidification in the irradiated enamel and dentin samples with the CO{sub 2} laser (9.6 {mu}m), creating a vitrified layer with tiny craters. With the Er:YAG laser (2.94 {mu}m) there were typical morphological explosive microablation with the exposition of the tubules in the dentin.The surface acquired by the association of the CO{sub 2} laser ( 9.6 {mu}m) plus acid etching no longer presented the aspect of fusion being this layer completely removed. There were statistical significant differences among ali three methods of etching in the treatment of the enamel and dentin surface. The tensile bond strength test showed that etching of these enamel and dentin surfaces with acid exclusively (control group) presented great values, surpassing the values of the etching acquired with the Er:YAG laser (2.94 {mu}) plus acid or the CO{sub 2} laser (9.6 {mu}m) plus acid. With the parameters used in this experiment the Er:YAG laser (2.94 {mu}m) showed to be more effective than the CO{sub 2} laser (9.6 {mu}m) for the hard dental surfaces etching procedure. (author)

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 hy...

Influence of multi-wavelength laser irradiation of enamel and dentin surfaces at 0.355, 2.94, and 9.4 μm on surface morphology, permeability, and acid resistance.

Science.gov (United States)

Chang, Nai-Yuan N; Jew, Jamison M; Simon, Jacob C; Chen, Kenneth H; Lee, Robert C; Fried, William A; Cho, Jinny; Darling, Cynthia L; Fried, Daniel

2017-12-01

Ultraviolet (UV) and infrared (IR) lasers can be used to specifically target protein, water, and mineral, respectively, in dental hard tissues to produce varying changes in surface morphology, permeability, reflectivity, and acid resistance. The purpose of this study was to explore the influence of laser irradiation and topical fluoride application on the surface morphology, permeability, reflectivity, and acid resistance of enamel and dentin to shed light on the mechanism of interaction and develop more effective treatments. Twelve bovine enamel surfaces and twelve bovine dentin surfaces were irradiated with various combinations of lasers operating at 0.355 (Freq.-tripled Nd:YAG (UV) laser), 2.94 (Er:YAG laser), and 9.4 μm (CO 2 laser), and surfaces were exposed to an acidulated phosphate fluoride gel and an acid challenge. Changes in the surface morphology, acid resistance, and permeability were measured using digital microscopy, polarized light microscopy, near-IR reflectance, fluorescence, polarization sensitive-optical coherence tomography (PS-OCT), and surface dehydration rate measurements. Different laser treatments dramatically influenced the surface morphology and permeability of both enamel and dentin. CO 2 laser irradiation melted tooth surfaces. Er:YAG and UV lasers, while not melting tooth surfaces, showed markedly different surface roughness. Er:YAG irradiation led to significantly rougher enamel and dentin surfaces and led to higher permeability. There were significant differences in acid resistance among the various treatment groups. Surface dehydration measurements showed significant changes in permeability after laser treatments, application of fluoride and after exposure to demineralization. CO 2 laser irradiation was most effective in inhibiting demineralization on enamel while topical fluoride was most effective for dentin surfaces. Lasers Surg. Med. 49:913-927, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

CO2 electric discharge lasers - Present status and future applications

International Nuclear Information System (INIS)

Reilly, J.P.

1979-01-01

CO 2 electric discharge lasers (EDLs) have proven themselves to be efficient sources of high-power high-quality laser energy. The paper outlines applications of high-power CO 2 EDLs, applications which are now becoming commercially viable, as well as those which are still being investigated in research laboratories. Applications of CO 2 lasers are discussed relative to industrial applications (laser welding, laser surface hardening, heat treatment, and surface chemistry modification by laser alloying and laser glazing), laser radar applications, laser-induced fusion, and laser propulsion. Attention is given to requirements of applications versus status of technology. Examples are given of the engineering solutions used to address the technology issues identified by particular laser applications

Longitudinally excited CO2 laser with multiple laser tubes

Science.gov (United States)

Uno, Kazuyuki; Akitsu, Tetsuya; Jitsuno, Takahisa

2016-11-01

We developed a longitudinally excited CO2 laser system that was constituted of two or three laser tubes and a single driving circuit. The multiple laser tubes simultaneously produced almost the same short laser pulses with a spike pulse width of about 164 ns and a pulse tail length of about 74 μs with a single driving circuit. The double-tube system was constituted of two 30 cm-long laser tubes with inner diameters of 13 mm and 16 mm and a single driving circuit with an input energy of 2.18 J. The output energy of the 13 mm-tube was 23.3 mJ, and that of the 16 mm-tube was 21.9 mJ at a gas pressure of 4.2 kPa (CO2:N2:He = 1:1:2). The triple-tube system was constituted of three 30 cm-long laser tubes with inner diameters of 9 mm, 13 mm, and 16 mm and a single driving circuit with an input energy of 2.18 J. The output energy of the 9 mm tube was 15.9 mJ, that of the 13 mm tube was 24.1 mJ, and that of the 16 mm tube was 19.2 mJ at a gas pressure of 4.2 kPa. With the same driving circuit and the same input energy, the total output energies of the multitube laser systems were higher than the output energy of a single-tube system.

Multistage plasma initiation process by pulsed CO2 laser irradiation of a Ti sample in an ambient gas (He, Ar, or N2)

Science.gov (United States)

Hermann, J.; Boulmer-Leborgne, C.; Mihailescu, I. N.; Dubreuil, B.

1993-02-01

New experimental results are reported on plasma initiation in front of a titanium sample irradiated by ir (λ=10.6 μm) laser pulses in an ambient gas (He, Ar, and N2) at pressures ranging from several Torr up to the atmosphere. The plasma is studied by space- and time-resolved emission spectroscopy, while sample vaporization is probed by laser-induced fluorescence spectroscopy. Threshold laser intensities leading to the formation of a plasma in the vapor and in the ambient gases are determined. Experimental results support the model of a vaporization mechanism for the plasma initiation (vaporization-initiated plasma breakdown). The plasma initiation is described by simple numerical criteria based on a two-stage process. Theoretical predictions are found to be in a reasonable agreement with the experiment. This study provides also a clear explanation of the influence of the ambient gas on the laser beam-metal surface energy transfer. Laser irradiation always causes an important vaporization when performed in He, while in the case of Ar or N2, the interaction is reduced in heating and vaporization of some surface defects and impurities.

Investigation of scleral buckling by CO{sub 2} laser

Energy Technology Data Exchange (ETDEWEB)

Maswadi, S

2001-05-01

This thesis investigates the effect of using the infrared wavelength CO{sub 2} laser (10.6{mu}m) as a localised heat source for inducing scleral buckling on eyes. Retinal detachment disease is a major cause of blindness and the scleral buckling is an important technique used in treatment. A radio-frequency excited 10.6{lambda}m laser source is used to heat collagen in the sclera above its shrinkage temperature so as to produce a localised indentation and deformation in the human eye (in vitro). Basic measurements of the onset shrinkage temperatures of porcine and human sclera are taken. Optical properties of sclera tissue at 10.6{mu}m are also determined to provide information about the interaction of the CO{sub 2} laser with the sclera. It is found that CO{sub 2} laser radiation is highly absorbed by the scleral water. Optical diffraction technique is investigated to quantify in-plane deformation in the sclera tissue as result of heating by producing grating on porcine and human sclera using the ArF laser (193nm). Photothermal deflection technique is also used to investigate scleral ablation by using the TEA and Ultrapulse CO{sub 2} laser. This technique provides a useful guide to the regime where ablation rather than heat shrinkage of collagen in the sclera will dominate using the Ultrapulse CO{sub 2} laser. A quantitative assessment of buckling using the technique of projection moire interferometry is described which allows a non-contact measurement to be made of the out-of-plane displacement by laser radiation. In-plane surface strain (shrinkage) has also been demonstrated using in-situ optical microscopy of the laser treated eye. The moire method is suitable to obtain information on buckling in real time and to obtain a three-dimensional view of the eye surface as laser treatment proceeds. A theoretical heat flow model is described for predicting the temperature profile produced in the sclera using the Ultrapulse CO{sub 2} laser. For appropriate exposure

Controlling chaotic behavior in CO2 and other lasers

Science.gov (United States)

1993-06-01

Additional substantial experimental progress has been made, in the third month of the project, in setting up equipment and testing for producing chaotic behavior with a CO2 laser. The project goal is to synchronize and control chaos in CO2 and other lasers, and thereby increase the power in ensembles of coupled laser sources. Numerous investigations into the chaos regime have been made, a second CO2 laser has been brought on stream, and work is progressing in the fourth month toward coupling the two lasers and control of the first laser. It is also intended to submit at least two papers to the Second Experimental Chaos Conference which is supported by the Office of Naval Research. Abstracts to those two papers are attached. Last month's report discussed the experimental investigation of nonlinear dynamics of CO2 lasers which involved a new technique of inducing chaos. In this new technique, an acoustically modulated feedback of the laser light was used and led to chaotic dynamics at a very low modulation frequency of 375 Hz. Since then, new results have been obtained by an Electro-Optical Modulation (EOM) technique. In the new setup, the electro-optical modulator is placed in an external cavity outside the laser.

Dentinal temperature transients caused by exposure to CO2 laser irradiation and possible pulpal damage.

Science.gov (United States)

Jeffrey, I W; Lawrenson, B; Saunders, E M; Longbottom, C

1990-02-01

An investigation is described that attempts to establish, in vitro, the characteristics of heat transference following laser irradiation of bovine dentinal tissue and the relationship with the periodicity of radiation. The results of this study appear to indicate that at depths of overlying dentine of up to 3 mm, laser-induced thermal injury to the pulp is a definite possibility. Fail-safe facilities to prevent build up of heat must be incorporated into the design of dental lasers to allow their beneficial effects to be utilized without the risk of iatrogenic damage.

Laser-induced breakdown spectroscopy with laser irradiation resonant with vibrational transitions

International Nuclear Information System (INIS)

Khachatrian, Ani; Dagdigian, Paul J.

2010-01-01

An investigation of laser-induced breakdown spectroscopy (LIBS) of polymers, both in bulk form and spin coated on Si wafers, with laser irradiation in the mid-infrared spectral region is presented. Of particular interest is whether the LIBS signals are enhanced when the laser wavelength is resonant with a fundamental vibrational transition of the polymer. Significant increases in the LIBS signals were observed for irradiation on hydride stretch fundamental transitions, and the magnitude of the enhancement showed a strong dependence on the mode excited. The role of the substrate was investigated by comparison of results for bulk and spin-coated samples. The polymers investigated were Nylon 12 and poly(vinyl alcohol-co-ethylene).

One-Pot Hybrid SnO2 /Poly(methyl methacrylate) Nanocomposite Formation through Pulsed Laser Irradiation.

Science.gov (United States)

Caputo, Gianvito; Scarpellini, Alice; Palazon, Francisco; Athanassiou, Athanassia; Fragouli, Despina

2017-06-20

The localized in situ formation of tin dioxide (SnO 2 ) nanoparticles embedded in poly(methyl methacrylate) (PMMA) films is presented. This is achieved by the photoinduced conversion of the tin acetate precursor included in polymeric films, through controlled UV or visible pulsed laser irradiation at λ=355 and 532 nm, respectively. The evolution of the formation of nanoparticles is followed by UV/Vis spectroscopy and shows that their growth is affected in different ways by the laser pulses at the two applied wavelengths. This, in combination with electron microscopy analysis, reveals that, depending on the irradiation wavelength, the size of the nanoparticles in the final nanocomposites differs. This difference is attributed to distinct mechanistic pathways that lead to the synthesis of small nanoparticles (from 1.5 to 4.5 nm) at λ=355 nm, whereas bigger ones (from 5 to 16 nm) are formed at λ=532 nm. At the same time, structural studies with both X-ray and electron diffraction measurements demonstrate the crystallinity of SnO 2 nanoparticles in both cases, whereas XPS analysis confirms the light-induced oxidation of tin acetate into SnO 2 . Taken all together, it is demonstrated that the pulsed laser irradiation at λ=355 and 532 nm leads to the formation of SnO 2 nanoparticles with defined features highly dispersed in PMMA solid matrices. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gain measurements in CO2 CW low pressure lasers

International Nuclear Information System (INIS)

Rodrigues, N.A.S.; Chanes Junior, J.B.; Jayaram, K.

1983-01-01

A series of gain measurements in low pressure CO 2 CW laser were performed in order to study the behaviour of a CO 2 laser ampliflier as a function of pressure and discharge current. A theoretical model, based on rate equations is also presented to describe the laser behaviour and the experimental procedure adopted. (C.L.B.) [pt

Experimental Study of 5-fluorouracil Encapsulated Ethosomes Combined with CO2 Fractional Laser to Treat Hypertrophic Scar.

Science.gov (United States)

Zhang, Zhen; Chen, Jun; Huang, Jun; Wo, Yan; Zhang, Yixin; Chen, Xiangdong

2018-01-18

This study is designed to explore permeability of ethosomes encapsulated with 5-florouracil (5-FU) mediated by CO 2 fractional laser on hypertrophic scar tissues. Moreover, therapeutic and duration effect of CO 2 fractional laser combined with 5-FU encapsulated ethosomes in rabbit ear hypertrophic scar model will be evaluated. The permeated amount of 5-FU and retention contents of 5-FU were both determined by high-performance liquid chromatography (HPLC). Fluorescence intensities of ethosomes encapsulated with 5-FU (5E) labeled with Rodanmin 6GO (Rho) were measured by confocal laser scanning microscopy (CLSM). The permeability promotion of 5E labeled with Rho in rabbit ear hypertrophic scar mediated by CO 2 fractional laser was evaluated at 0 h, 6 h, 12 h, 24 h, 3 days and 7 days after the irradiation. The opening rates of the micro-channels were calculated according to CLSM. The therapeutic effect of 5EL was evaluated on rabbit ear hypertrophic scar in vivo. Relative thickness of rabbit ear hypertrophic scar before and after the treatment was measured by caliper method. Scar elevation index (SEI) of rabbit ear hypertrophic scar was measured using H&E staining. The data showed that the penetration amount of 5EL group was higher than 5E group (4.15 ± 2.22 vs. 0.73 ± 0.33; p 5E group (107.61 ± 13.27 vs. 20.73 ± 3.77; p 5E group (24.42 ± 4.37 vs.12.25 ± 1.64; p 5E group at different time points (1, 6, and 24 h). The opening rates of the micro-channels were decreased gradually within 24 h, and micro-channels were closed completely 3 days after the irradiation by CO 2 fractional laser. The relative thickness and SEI of rabbit ear hypertrophic scar after 7 days of treatment in the 5EL group were significantly lower than the 5E group. CO 2 fractional laser combined with topical 5E can be effective in the treatment of hypertrophic scar in vivo and supply a novel therapy method for human hypertrophic scar.

Cutting using the CO laser. Trennen mit dem CO-Laser

Energy Technology Data Exchange (ETDEWEB)

Maisenhaelder, F.; Stoehr, M. (DLR, Inst. fuer Technische Physik, Stuttgart (Germany))

1991-02-01

Several cutting experiments were performed to investigate the maximum cutting speed when using CO or CO{sub 2} laser radiation. The material which was used for these experiments was mild steel (St 37) and stainless steel (V2A; X5CrNi 189), the material thickness varied from 0.5 mm to 4 mm. The cutting parameters, especially the focal power density and the focal diameter, were equal for both laser wavelengths. The experimental result shows an increased cutting speed with CO laser beams in comparison to CO{sub 2} laser beams.

Development of longitudinally excited CO2 laser

Science.gov (United States)

Masroon, N. S.; Tanaka, M.; Tei, M.; Uno, K.; Tsuyama, M.; Nakano, H.

2018-05-01

Simple, compact, and affordable discharged-pumped CO2 laser controlled by a fast high voltage solid state switch has been developed. In this study, longitudinal excitation scheme has been adapted for simple configuration. In the longitudinal excitation scheme, the discharge is produced along the direction of the laser axis, and the electrodes are well separated with a small discharge cross-section. Triggered spark gap switch is usually used to switch out the high voltage because of simple and low cost. However, the triggered spark gap operates in the arc mode and suffer from recovery problem causing a short life time and low efficiency for high repetition rate operation. As a result, there is now considerable interest in replacing triggered spark gap switch with solid state switches. Solid state switches have significant advantages compared to triggered spark gap switch which include longer service lifetime, low cost and stable high trigger pulse. We have developed simple and low cost fast high voltage solid state switch that consists of series connected-MOSFETs. It has been installed to the longitudinally excited CO2 laser to realize the gap switch less operation. Characteristics of laser oscillation by varying the discharge length, charging voltage, capacitance and gas pressure have been evaluated. Longer discharge length produce high power of laser oscillation. Optimum charging voltage and gas pressure were existed for longitudinally excited CO2 laser.

CO2 and diode laser welding of AZ31 magnesium alloy

International Nuclear Information System (INIS)

Zhu Jinhong; Li Lin; Liu Zhu

2005-01-01

Magnesium alloys are being increasingly used in automotive and aerospace structures. Laser welding is an important joining method in such applications. There are several kinds of industrial lasers available at present, including the conventional CO 2 and Nd:YAG lasers as well as recently available high power diode lasers. A 1.5 kW diode laser and a 2 kW CO 2 laser are used in the present study for the welding of AZ31 alloys. It is found that different welding modes exist, i.e., keyhole welding with the CO 2 laser and conduction welding with both the CO 2 and the diode lasers. This paper characterizes welds in both welding modes. The effect of beam spot size on the weld quality is analyzed. The laser processing parameters are optimized to obtain welds with minimum defects

Analyses of surface coloration on TiO2 film irradiated with excimer laser

International Nuclear Information System (INIS)

Zheng, H.Y.; Qian, H.X.; Zhou, W.

2008-01-01

TiO 2 film of around 850 nm in thickness was deposited on a soda-lime glass by PVD sputtering and irradiated using one pulse of krypton-fluorine (KrF) excimer laser (wavelength of 248 nm and pulse duration of 25 ns) with varying fluence. The color of the irradiated area became darker with increasing laser fluence. Irradiated surfaces were characterized using optical microscopy, scanning electron microscopy, Raman spectroscopy and atomic force microscopy. Surface undergoes thermal annealing at low laser fluence of 400 and 590 mJ/cm 2 . Microcracks at medium laser fluence of 1000 mJ/cm 2 are attributed to surface melting and solidification. Hydrodynamic ablation is proposed to explain the formation of micropores and networks at higher laser fluence of 1100 and 1200 mJ/cm 2 . The darkening effect is explained in terms of trapping of light in the surface defects formed rather than anatase to rutile phase transformation as reported by others. Controlled darkening of TiO 2 film might be used for adjustable filters

Application of CO2 laser cutting machine to shipbuilding; Zosen no setsudan eno CO2 laser no tekiyo

Energy Technology Data Exchange (ETDEWEB)

Fujimoto, Y. [Mitsui Engineering and Shipbuilding Co. Ltd., Tokyo (Japan)

1998-11-01

Carbon dioxide laser has been applied to cutting works in shipbuilding. As NC cutter was obsolete, CO2 laser cutting machine with a rated output 3 kW was introduced. According to the specifications of the machinable plate, the maximum thickness is 19 mm, and effective width and length are 5.4 m and 29.1 m, respectively. As the cutting width is wide and the running distance of laser beam is long, the error of light axis is expanded only by a small error of irradiation angle, which results in the inconvenience. Stable operation was realized by improving the fixation of reflecting mirror. Right angle cutting section with a cutting curve below 0.5 mm was obtained, and cutting time was reduced by the one-line cutting by which both sections can be available with a single cutting line. For the cutting of thin plate with a thickness less than 10 mm, strain was not formed, and remedy was not required. Block strain was remarkably reduced during the assembly process. Maintenance-free operation without monitoring can be performed for a long time. This machine is operated at night and lunch time, resulting in the reduced processes. The working environment is appropriate without noise and dust. Facility cost and maintenance cost were also reduced. Lower cutting speed is a weak point, when compared with the plasma cutting machine. The present machine is not applied to aluminum plates with high surface reflectivity. 13 figs.

Pulsed CH3OH terahertz laser radiation pumped by 9P(36) CO2 lasers

International Nuclear Information System (INIS)

Jiu Zhixian; Zuo Duluo; Miao Liang; Cheng Zuhai

2011-01-01

An efficient pulsed CH 3 OH terahertz (THz) laser pumped by a TEA CO 2 laser was investigated experimentally. A simple terahertz cavity and a TEA CO 2 laser for the optically pumped THz radiation were studied experimentally. To improve THz laser energy and photon conversion efficiency, two different TEA CO 2 lasers were developed to pump CH 3 OH. When CH 3 OH was pumped by the 9P(36) line with different powers of the CO 2 laser, the generation of terahertz radiation with energy as high as 0.307mJ and 23.75mJ were obtained, respectively. The corresponding photon conversion efficiencies were 0.29% and 2.4%. The photon conversion efficiency increases by a factor of about 8. Meanwhile, higher peak power of pump laser effectively improves the photon conversion efficiency. And the optimum THz laser pressure increases with narrower pulse width of pump laser because of increasing absorptive gases molecules of CH 3 OH with higher peak power of pump laser.

Factors affecting color strength of printing on film-coated tablets by UV laser irradiation: TiO2 particle size, crystal structure, or concentration in the film, and the irradiated UV laser power.

Science.gov (United States)

Hosokawa, Akihiro; Kato, Yoshiteru

2011-08-01

The purpose of this article is to study factors affecting color strength of printing on film-coated tablets by ultraviolet (UV) laser irradiation: particle size, crystal structure, or concentration of titanium dioxide (TiO2) in film, and irradiated UV laser power. Hydroxypropylmethylcellulose films containing 4.0% of TiO2, of which BET particle sizes were ranging from 126.1 to 219.8 nm, were irradiated 3.14W of UV laser at a wavelength 355 nm to study effects of TiO2 particle size and crystal structure on the printing. The films containing TiO2 concentration ranging from 1.0 to 7.7% were irradiated 3.14 or 5.39W of the UV laser to study effect of TiO2 concentration on the printing. The film containing 4.0% of TiO2, was irradiated the UV laser up to 6.42W to study effect of the UV laser power on the printing. The color strength of the printed films was estimated by a spectrophotometer as total color difference (dE). Particle size, crystal structure, and concentration of TiO2 in the films did not affect the printing. In the relationship between the irradiated UV laser power and dE, there found an inflection point (1.6W). When the UV laser power was below 1.6W, the films were not printed. When it was beyond the point, total color difference increased linearly in proportion with the irradiated laser power. The color strength of the printing on film was not changed by TiO2 particle size, crystal structure, and concentration, but could be controlled by regulating the irradiated UV laser power beyond the inflection point.

Acquired acid resistance of human enamel treated with laser (Er:YAG laser and Co 2 laser and acidulated phosphate fluoride treatment: An in vitro atomic emission spectrometry analysis

Directory of Open Access Journals (Sweden)

Anju Mathew

2013-01-01

Full Text Available Background: Dental caries is essentially a process of diffusion and dissolution. If the aspect of dissolution can be curtailed some degree of prevention can be achieved. Aims: The present study was carried out to evaluate and compare the effect of Er:YAG laser and Co 2 laser irradiation combined with acidulated phosphate fluoride treatment on in vitro acid resistance of human enamel. Design: An in vitro study was carried out on 30 human premolars to evaluate the enamel′s acid resistance using an atomic emission spectrometry analysis. Materials and Methods: A total of 60 enamel specimens were prepared from 30 human premolars and were randomly assigned to 6 groups: (1 Untreated (control; (2 1.23% acidulated phosphate fluoride (APF gel application alone for 4 min; (3 Er:YAG laser treatment alone; (4 Co 2 laser treatment alone; (5 Er:YAG laser + APF gel application; (6 Co 2 laser + APF gel application. The specimens were then individually immersed in 5 ml of acetate buffer solution (0.1 mol/L, pH 4.5 and incubated at 37°C for 24 h, and the acid resistance was evaluated by determining the calcium ion concentration using the atomic emission spectrometry. Statistical Analysis: An ANOVA model was constructed (P value of 0.05, followed by Tukey′s test for multiple pair wise comparisons of mean values. Results: Significant differences were found between the control group and the test groups ( P < 0.001. Conclusions: Combining acidulated phosphate fluoride with either Er:YAG or Co 2 laser had a synergistic effect in decreasing the enamel demineralization more than either fluoride treatment or laser treatment alone.

High-powered CO2 -lasers and noise control

Science.gov (United States)

Honkasalo, Antero; Kuronen, Juhani

High-power CO2 -lasers are being more and more widely used for welding, drilling and cutting in machine shops. In the near future, different kinds of surface treatments will also become routine practice with laser units. The industries benefitting most from high power lasers will be: the automotive industry, shipbuilding, the offshore industry, the aerospace industry, the nuclear and the chemical processing industries. Metal processing lasers are interesting from the point of view of noise control because the working tool is a laser beam. It is reasonable to suppose that the use of such laser beams will lead to lower noise levels than those connected with traditional metal processing methods and equipment. In the following presentation, the noise levels and possible noise-control problems attached to the use of high-powered CO2 -lasers are studied.

Morphological and spectroscopic characterization of laser-ablated tungsten at various laser irradiances

Energy Technology Data Exchange (ETDEWEB)

Akram, Mahreen; Bashir, Shazia; Hayat, Asma; Mahmood, Khaliq; Dawood, Asadullah [Government College University, Centre for Advanced Studies in Physics, Lahore (Pakistan); Rafique, Muhammad Shahid [University of Engineering and Technology, Department of Physics, Lahore (Pakistan); Bashir, M.F. [COMSATS Institute of Information Technology, Department of Physics, Lahore (Pakistan)

2015-06-15

The variation in surface morphology and plasma parameters of laser irradiated tungsten has been investigated as a function of irradiance. For this purpose, Nd:YAG laser (1064 nm, 10 ns, 10 Hz) is employed. Tungsten targets were exposed to various laser irradiances ranging from 6 to 50 GW/cm{sup 2} under ambient environment of argon at a pressure of 20 Torr. Scanning electron microscope analysis has been performed to analyze the surface modification of irradiated tungsten. It revealed the formation of micro- and nanoscale surface structures. In central ablated area, distinct grains and crack formation are observed, whereas peripheral ablated areas are dominated by cones and pinhole formation. It was observed that at irradiances exceeding a value of 13 GW/cm{sup 2}, the morphological trend of the observed structures has been changed from erosion to melting and re-deposition dominant phase. Ablation efficiency as a function of laser irradiance has also been investigated by measuring the crater depth using surface profilometry analysis. It is found to be maximum at an irradiance of 13 GW/cm{sup 2} and decreases at high laser irradiances. In order to correlate the accumulated effects of plasma parameters with the surface modification, laser-induced breakdown spectroscopy analysis has been performed. The electron temperature and number density of tungsten plasma have been evaluated at various laser irradiances. Initially with the increase of the laser irradiance up to 13 GW/cm{sup 2}, an increasing trend is observed for both plasma parameters due to enhanced energy deposition. Afterward, a decreasing trend is achieved which is attributed to the shielding effect. With further increase in irradiance, a saturation stage comes and insignificant changes are observed in plasma parameters. This saturation is explainable on the basis of the formation of a self-regulating regime near the target surface. Surface modifications of laser irradiated tungsten have been correlated with

Long-lived CO/sub 2/ lasers with distributed heterogeneous catalysis

Energy Technology Data Exchange (ETDEWEB)

Browne, P G; Smith, A L.S.

1974-12-11

In a sealed CO/sub 2/-N/sub 2/-He system with a clean discharge tube the degree of dissociation of the CO/sub 2/ is greater than 80 percent (with no hydrogen present), and laser action cannot be obtained. If Pt is distributed along the discharge tube walls as a discontinuous film it catalyses back-reactions reforming CO/sub 2/. The degree of dissociation is then less than 40 percent, and efficient laser action at 10.6 ..mu.. is obtained. Using such distributed heterogeneous catalysis, a CO/sub 2/-N/sub 2/-He-Xe laser has operated for more than 3000 h. In this system, both H/sub 2/ and D/sub 2/ are undesirable additives because they decrease the excitation rate of the upper laser level. (auth)

Epiglottis reshaping using CO2 laser: A minimally invasive technique and its potent applications

Directory of Open Access Journals (Sweden)

Velegrakis George

2008-07-01

Full Text Available Abstract Laryngomalacia (LRM, is the most common laryngeal abnormality of the newborn, caused by a long curled epiglottis, which prolapses posteriorly. Epiglottis prolapse during inspiration (acquired laryngomalacia is an unusual cause of airway obstruction and a rare cause of obstructive sleep apnea syndrome (OSAS. We present a minimally invasive technique where epiglottis on cadaveric larynx specimens was treated with CO2 laser. The cartilage reshaping effect induced by laser irradiation was capable of exposing the glottis opening widely. This technique could be used in selected cases of LRM and OSAS due to epiglottis prolapse as an alternative, less morbid approach.

Isotopic separation of carbon by dissociation of CF2HCl irradiated by a Q-modulated CO2 laser

International Nuclear Information System (INIS)

Ezubchenko, A.N.; Ilyukhin, A.I.; Karchevskii, A.I.; Krasnikov, N.S.; Merzylakov, A.V.; Soloukhin, A.B.

1993-01-01

Isotopic separation of carbon by selective dissociation of CF 2 HCl by radiation from a CO 2 laser with mechanical Q-modulation has been studied experimentally. The modulation frequency was 10 4 sec -1 with a 20 W output. The peak radiation intensity is increased by a factor of 20-100 when modulated, while the average power is 0.5-0.9 that of the laser when operating in continuous mode. The authors show that under these conditions, a separation coefficient on the order of 40-50 is achieved as well as a high degree of the target isotope extraction (70%)

Multi - pulse tea CO2 laser beam interaction with the TiN thin films

International Nuclear Information System (INIS)

Gakovic, B.; Trtica, M.; Nenadovic, T.; Pavlicevic, B.

1998-01-01

The interaction of various types of energetic beams including a laser beam with the high-hardness coatings is of great fundamental and technological interest. The Nd:YAG, excimer and CO 2 are frequently used laser beams for this purpose. The interaction of a laser beam with low thickness coatings, deposited on austenitic stainless steel, is insufficiently known in the literature. Titanium nitride (TiN) possess the excellent physico-chemical characteristics. For this reason TiN films/coatings are widely used. The purpose of this article is a consideration of the effect of TEA C0 2 laser radiation on the TiN film deposited on austenitic stainless steel substrate (AISI 316). Investigation of TiN morphological changes, after multipulse laser irradiation, shown dependence on laser fluence, number of laser pulses and the laser pulse shape. Subsequently fast heating and cooling during multi-pulse laser bombardment cause the grain growth of TiN layer. Both laser pulses (pulses with tail and tail-free pulses) produced periodical wave like structure on polished substrate material. Periodicity is observed also on AISI 316 protected with TiN layer, but only with laser pulse with tail. (author)

Potential of sub-ablative pulsed CO{sub 2} laser irradiation on inhibition of artificial caries-like lesion progress in bovine dental enamel; Potencial de inibicao da progressao da carie artificial por irradiacao sub-ablativa com laser de CO{sub 2} pulsado em esmalte dental bovino

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Marcella Esteves

2005-07-01

of the irradiated samples showed less porous and smoother surfaces than the control. After demineralization the control and LA samples showed greater porosity and higher enamel rods dissolution. At the LB mild surface dissolution, presenting less porosity and with formation of crystals suggesting the presence of Ca-deficient apatites. In summary, it can be concluded that the 0,7 J/cm{sup 2} pulsed CO{sub 2} laser irradiation of bovine enamel was capable of reducing the enamel acid solubility without causing damage to the surface and therefore is a potential method of caries prevention. (author)

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.

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...

The feasibility of TEA CO2 laser-induced plasma for spectrochemical analysis of geological samples in simulated Martian conditions

Science.gov (United States)

Savovic, Jelena; Stoiljkovic, Milovan; Kuzmanovic, Miroslav; Momcilovic, Milos; Ciganovic, Jovan; Rankovic, Dragan; Zivkovic, Sanja; Trtica, Milan

2016-04-01

The present work studies the possibility of using pulsed Transversely Excited Atmospheric (TEA) carbon dioxide laser as an energy source for laser-induced breakdown spectroscopy (LIBS) analysis of rocks under simulated Martian atmospheric conditions. Irradiation of a basaltic rock sample with the laser intensity of 56 MW cm- 2, in carbon-dioxide gas at a pressure of 9 mbar, created target plasma with favorable conditions for excitation of all elements usually found in geological samples. Detection limits of minor constituents (Ba, Cr, Cu, Mn, Ni, Sr, V, and Zr) were in the 3 ppm-30 ppm range depending on the element. The precision varied between 5% and 25% for concentration levels of 1% to 10 ppm, respectively. Generally, the proposed relatively simple TEA CO2 laser-LIBS system provides good sensitivity for geological studies under reduced CO2 pressure.

Enhancing caries resistance with a short-pulsed CO2 9.3-μm laser: a laboratory study (Conference Presentation)

Science.gov (United States)

Rechmann, Peter; Rechmann, Beate M.; Groves, William H.; Le, Charles; Rapozo-Hilo, Marcia L.; Featherstone, John D. B.

2016-02-01

The objective of this laboratory study was to test whether irradiation with a new 9.3µm microsecond short-pulsed CO2-laser enhances enamel caries resistance with and without additional fluoride applications. 101 human enamel samples were divided into 7 groups. Each group was treated with different laser parameters (Carbon-dioxide laser, wavelength 9.3µm, 43Hz pulse-repetition rate, pulse duration between 3μs to 7μs (1.5mJ/pulse to 2.9mJ/pulse). Using a pH-cycling model and cross-sectional microhardness testing determined the mean relative mineral loss delta Z (∆Z) for each group. The pH-cycling was performed with or without additional fluoride. The CO2 9.3μm short-pulsed laser energy rendered enamel caries resistant with and without additional fluoride use.

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.

Modeling CO2 Laser Ablative Impulse with Polymers

International Nuclear Information System (INIS)

Sinko, John E.; Phipps, Claude R.; Sasoh, Akihiro

2010-01-01

Laser ablation vaporization models have usually ignored the spatial dependence of the laser beam. Here, we consider effects from modeling using a Gaussian beam for both photochemical and photothermal conditions. The modeling results are compared to experimental and literature data for CO 2 laser ablation of the polymer polyoxymethylene under vacuum, and discussed in terms of the ablated mass areal density and momentum coupling coefficient. Extending the scope of discussion, laser ablative impulse generation research has lacked a cohesive strategy for linking the vaporization and plasma regimes. Existing models, mostly formulated for ultraviolet laser systems or metal targets, appear to be inappropriate or impractical for applications requiring CO 2 laser ablation of polymers. A recently proposed method for linking the vaporization and plasma regimes for analytical modeling is addressed here along with the implications of its use. Key control parameters are considered, along with the major propulsion parameters needed for laser ablation propulsion modeling.

Pulsed CO laser for isotope separation of uranium

Energy Technology Data Exchange (ETDEWEB)

Baranov, Igor Y.; Koptev, Andrey V. [Rocket-Space Technics Department, Baltic State Technical University, 1, 1st Krasnoarmeyskaya st.,St. Petersburg, 190005 (Russian Federation)

2012-07-30

This article proposes a technical solution for using a CO laser facility for the industrial separation of uranium used in the production of fuel for nuclear power plants, employing a method of laser isotope separation of uranium with condensation repression in a free jet. The laser operation with nanosecond pulse irradiation can provide an acceptable efficiency in the separating unit and a high efficiency of the laser with the wavelength of 5.3 {mu}m. In the present work we also introduce a calculation model and define the parameters of a mode-locked CO laser with a RF discharge in the supersonic stream. The average pulsed CO laser power of 3 kW is sufficient for efficient industrial isotope separation of uranium in one stage.

Fractional CO2 laser treatment for vaginal laxity: A preclinical study.

Science.gov (United States)

Kwon, Tae-Rin; Kim, Jong Hwan; Seok, Joon; Kim, Jae Min; Bak, Dong-Ho; Choi, Mi-Ji; Mun, Seok Kyun; Kim, Chan Woong; Ahn, Seungwon; Kim, Beom Joon

2018-05-07

Various studies have investigated treatment for vaginal laxity with microablative fractional carbon dioxide CO 2 laser in humans; however, this treatment has not yet been studied in an animal model. Herein, we evaluate the therapeutic effects of fractional CO 2 laser for tissue remodeling of vaginal mucosa using a porcine model, with the aim of improving vaginal laxity. The fractional CO 2 laser enables minimally invasive and non-incisional procedures. By precisely controlling the laser energy pulses, energy is sent to the vaginal canal and the introitus area to induce thermal denaturation and contraction of collagen. We examined the effects of fractional CO 2 laser on a porcine model via clinical observation and ultrasound measurement. Also, thermal lesions were histologically examined via hematoxylin-eosin staining, Masson's trichrome staining, and Elastica van Gieson staining and immunohistochemistry. The three treatment groups, which were determined according to the amount of laser-energy applied (60, 90, and 120 mJ), showed slight thermal denaturation in the vaginal mucosa, but no abnormal reactions, such as excessive hemorrhaging, vesicles, or erythema, were observed. Histologically, we also confirmed that the denatured lamina propria induced by fractional CO 2 laser was dose-dependently increased after laser treatment. The treatment groups also showed an increase in collagen and elastic fibers due to neocollagenesis and angiogenesis, and the vaginal walls became firmer and tighter because of increased capillary and vessel formation. Also, use of the fractional CO 2 laser increased HSP (heat shock protein) 70 and collagen type I synthesis. Our results show that microablative fractional CO 2 laser can produce remodeling of the vaginal connective tissue without causing damage to surrounding tissue, and the process of mucosa remodeling while under wound dressings enables collagen to increase and the vaginal wall to become thick and tightened. Lasers Surg. Med

In-situ investigation of laser surface modifications of WC-Co hard metals inside a scanning electron microscope

Science.gov (United States)

Mueller, H.; Wetzig, K.; Schultrich, B.; Pompe, Wolfgang; Chapliev, N. I.; Konov, Vitaly I.; Pimenov, S. M.; Prokhorov, Alexander M.

1989-05-01

The investigation of laser interaction with solid surfaces and of the resulting mechanism of surface modification are of technical interest to optimize technological processes, and they are also of fundamental scientific importance. Most instructive indormation is available with the ail of the in-situ techniques. For instance, measuring of the photon emission of the irradiated surface ane the plasma torch (if it is produced) simultaneously to laser action, makes it possible to gain a global characterization of the laser-solid interaction. In order to obtain additional information about surface and structure modifications in microscopic detail , a laser and scanning electron microscope were combined in to a tandem equipment (LASEM). Inside this eqiipment the microscopic observation is carried out directly at the laser irradiated area without any displacement of the sample. In this way, the stepwise development of surface modification during multipulse irradiation is visible in microscopic details and much more reliable information about the surface modification process is obtainable in comparison to an external laser irradiation. Such kind of equipments were realized simultaneously and independently in the Institut of General Physics (Moscow) and the Central Institute of Solid State Physics and Material Research (Dresden) using a CO2 and a LTd-glass-laser, respectively. In the following the advantages and possibilities of a LASEM shall be demonstrated by some selected investigations of WC-CO hardmeta. The results were obtained in collaboration by both groups with the aid of the pulsed CO2-laser. The TEA CO2 laser was transmitted through a ZnSe-window into the sample chamber of the SEM and focused ofAo tfte sample surface. It was operated in TEM - oo mode with a repetition rate of about 1 pulse per second. A peak power density of about 160 MW/cm2 was achieved in front of the sample surface.

Parameter optimization for steel quenching by C02-laser irradiation

International Nuclear Information System (INIS)

Moryashchev, S.F.; Kislitsyn, A.A.; Kosyrev, F.K.

1984-01-01

The dependence of average absorption factor on maximal temperature of the article surface during quenching by CO 2 -laser irradiation was determined empirically. The calculations of depth of a hardening zone and process productivity in 40 Kh, 4Kh13 steels and Armco-iron with regard to this dependence were conducted

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.

Highly efficient repetitively pulsed electric-discharge industrial CO2 laser

International Nuclear Information System (INIS)

Osipov, V V; Ivanov, M G; Lisenkov, V V; Platonov, V V

2002-01-01

The results of investigations aimed at the development of a repetitively pulsed CO 2 laser with an active medium volume of 1000 cm 3 pumped by a combined discharge are generalised. It is shown that, at pump pulse durations of 200-500 μs the optimal characteristics are achieved at active-medium pressures of 60-100 Torr. In this case, the laser efficiency at the initial stage of its operation can reach 22% and; if the energy dissipated in the region of the cathode potential drop is neglected, the efficiency is 28%. After emission of 3x10 5 pulses, the laser efficiency falls to 12%. It has been found that adding CO with a relative concentration [CO]/[CO 2 ] ∼0.75 increases the input and output power by almost 50%. The lasing efficiency is then 10%-12%, and the service life of the laser is by more than 10 6 pulses with a power decrease of no more than 10%. Adding hydrogen up to a concentration [H 2 ]/[CO 2 ] ∼10 leads to an increase in the energy supplied to the gas due to a decrease in the rate of ionisation processes. However, the optimal ratio is [H 2 ]/[CO 2 ] ∼ 1, at which the output power increases by 15%. In a long-term operating mode, the laser power is 1 kW at a peak power of 10 kW and an efficiency of 12%. (lasers)

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....

Approach to compact terawatt CO2 laser system for particle acceleration

International Nuclear Information System (INIS)

Pogorelsky, I.V.; Kimura, W.D.; Fisher, C.H.; Kannari, F.

1994-01-01

A compact table-top 20-GW 50-ps CO 2 laser system is in operation for strong-field physics studies at the ATF. We propose scaling up of the picosecond CO 2 laser to a terawatt peak power level to meet the requirements of advanced laser accelerators. Computer modeling shows that a relatively compact single-beam picosecond CO 2 laser system with a high-pressure x-ray picosecond amplifier of a 10-cm aperture is potentially scalable to the ∼1-TW peak power level

Efficient TEA CO2 laser based coating removal system

CSIR Research Space (South Africa)

Prinsloo, FJ

2007-04-01

Full Text Available stream_source_info Prinsloo_2007.pdf.txt stream_content_type text/plain stream_size 11617 Content-Encoding UTF-8 stream_name Prinsloo_2007.pdf.txt Content-Type text/plain; charset=UTF-8 Efficient TEA CO2 laser based... by keeping energy density below the damage threshold. The advantage of a pulsed TEA CO2 laser system is that a laser frequency and temporal profile can be chosen to maximize paint removal and concurrently minimize substrate damage. To achieve...

H+ irradiation effect in Co-doped BaFe2As2 single crystals

International Nuclear Information System (INIS)

Nakajima, Y.; Tsuchiya, Y.; Taen, T.; Tamegai, T.; Kitamura, H.; Murakami, T.

2011-01-01

The effect of H + irradiation on the suppression of Tc in Co-doped BaFe 2 As 2 . H + irradiation introduces nonmagnetic scattering centers. Critical Scattering rate is much higher than that expected in s±-pairing scenario. We report the suppression of the critical temperature T c in single crystalline Ba(Fe 1-x Co x ) 2 As 2 at under-, optimal-, and over-doping levels by 3 MeV proton irradiation. T c decreases and residual resistivity increases monotonically with increasing the dose. The low-temperature resistivity does not show the upturn in contrast with the α-particle irradiated NdFeAs(O,F), which suggests that proton irradiation introduces nonmagnetic scattering centers. Critical scattering rates for all samples obtained by three different ways are much higher than that expected in s±-pairing scenario based on inter-band scattering due to antiferro-magnetic spin fluctuations.

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.

Damage rates in neutron irradiated FeCo and FeCo2V ordered and disordered alloys

International Nuclear Information System (INIS)

Riviere, J.P.; Dinhut, J.F.

1979-01-01

Ordered and disordered samples of FeCo and FeCo2V alloys have been irradiated at liquid hydrogen temperature with fission neutrons up to an integrated dose of about 7.2 x 10 17 n/cm 2 (E > 1 MeV). During the irradiation, the resistivity increases continuously due to point defect production. (author)

CO2 laser pulse shortening by laser ablation of a metal target

International Nuclear Information System (INIS)

Donnelly, T.; Mazoyer, M.; Lynch, A.; O'Sullivan, G.; O'Reilly, F.; Dunne, P.; Cummins, T.

2012-01-01

A repeatable and flexible technique for pulse shortening of laser pulses has been applied to transversely excited atmospheric (TEA) CO 2 laser pulses. The technique involves focusing the laser output onto a highly reflective metal target so that plasma is formed, which then operates as a shutter due to strong laser absorption and scattering. Precise control of the focused laser intensity allows for timing of the shutter so that different temporal portions of the pulse can be reflected from the target surface before plasma formation occurs. This type of shutter enables one to reduce the pulse duration down to ∼2 ns and to remove the low power, long duration tails that are present in TEA CO 2 pulses. The transmitted energy is reduced as the pulse duration is decreased but the reflected power is ∼10 MW for all pulse durations. A simple laser heating model verifies that the pulse shortening depends directly on the plasma formation time, which in turn is dependent on the applied laser intensity. It is envisaged that this plasma shutter will be used as a tool for pulse shaping in the search for laser pulse conditions to optimize conversion efficiency from laser energy to useable extreme ultraviolet (EUV) radiation for EUV source development.

Reduction of birefringence in a skin-layer of injection molded polymer strips using CO{sub 2} laser irradiation

Energy Technology Data Exchange (ETDEWEB)

Kurosaki, Yasuo; Satoh, Isao; Saito, Takushi [Tokyo Inst. of Tech. (Japan). Dept. of Mechanical Intelligent Systems Engineering

1995-12-31

Injection molding of polymers is currently utilized for numerous industrial applications. Because of high productivity and stable quality of molded products, the injection-molding process makes the production costs lower, and therefore, is expected to spread more widely in the future. This paper deals with a technique for improving the optical quality of injection molded polymer products using radiative heating. The birefringence frozen in a skin-layer of the molded part was reduced by CO{sub 2} laser heating, and the efficiency of this technique was investigated experimentally. Namely, a simple numerical calculation was performed to estimate the heating efficiency of CO{sub 2} laser in the polymer, effects of radiation heating on the skin-layer of the molded polymer were observed by using a mold with transparent windows, and the residual birefringence frozen in the final molded specimen was measured. The results clearly showed that the birefringence in the skin-layer of injection molded polymer strips was reduced with CO{sub 2} laser heating. The authors believe that the proposed method for reducing the birefringence frozen in injection-molded polymer products is suitable for practical molding, because process time required for the injection-molding is only slightly increased with this method.

Diffraction efficiency enhancement of femtosecond laser-engraved diffraction gratings due to CO2 laser polishing

International Nuclear Information System (INIS)

Choi, Hun-Kook; Jung, Deok; Sohn, Ik-Bu; Noh, Young-Chul; Lee, Yong-Tak; Kim, Jin-Tae; Ahsan, Shamim

2014-01-01

This research demonstrates laser-assisted fabrication of high-efficiency diffraction gratings in fused-silica glass samples. Initially, femtosecond laser pulses are used to engrave diffraction gratings on the glass surfaces. Then, these micro-patterned glass samples undergo CO 2 laser polishing process. unpolished diffraction gratings encoded in the glass samples show an overall diffraction efficiency of 18.1%. diffraction gratings imprinted on the glass samples and then polished four times by using a CO 2 laser beam attain a diffraction efficiency of 32.7%. We also investigate the diffraction patterns of the diffraction gratings encoded on fused-silica glass surfaces. The proposed CO 2 laser polishing technique shows great potential in patterning high-efficiency diffraction gratings on the surfaces of various transparent materials.

Laser plant "Iguana" for transmyocardial revascularization based on kW-level waveguide CO2 laser

Science.gov (United States)

Panchenko, Vladislav Y.; Bockeria, L. A.; Berishvili, I. I.; Vasiltsov, Victor V.; Golubev, Vladimir S.; Ul'yanov, Valery A.

2001-05-01

For many years the Institute on Laser and Information Technologies RAN has been developing a concept of high-power industrial CO2 lasers with diffusion cooling of the working medium. The paper gives a description of the laser medical system Iguana for transmyocardial laser revascularization (TMLR) as an example of various applications of high-power waveguide CO2 lasers. The clinical results of the TMLR method application in surgical treatment are presented. The methods of determination of the time, when the laser beam passes through the demarcation line between myocardium tissue and blood, are discussed.

INTERACTION OF LASER RADIATION WITH MATTER AND OTHER LASER APPLICATIONS: Changes in the emission properties of metal targets during pulse-periodic laser irradiation

Science.gov (United States)

Konov, Vitalii I.; Pimenov, S. M.; Prokhorov, A. M.; Chapliev, N. I.

1988-02-01

A scanning electron microscope was used with a pulse-periodic CO2 laser to discover the laws governing the correlation of the modified microrelief of metal surfaces, subjected to the action of multiple laser pulses, with the emission of charged particles and the luminescence of the irradiated zone. It was established that the influence of sorption and laser-induced desorption on the emission signals may be manifested differently depending on the regime of current generation in the "target-vacuum chamber" circuit.

Excimer laser irradiation of metal surfaces

Science.gov (United States)

Kinsman, Grant

In this work a new method of enhancing CO2 laser processing by modifying the radiative properties of a metal surface is studied. In this procedure, an excimer laser (XeCl) or KrF) exposes the metal surface to overlapping pulses of high intensity, 10(exp 8) - 10(exp 9) W cm(exp -2), and short pulse duration, 30 nsec FWHM (Full Width Half Maximum), to promote structural and chemical change. The major processing effect at these intensities is the production of a surface plasma which can lead to the formation of a laser supported detonation wave (LSD wave). This shock wave can interact with the thin molten layer on the metal surface influencing to a varying degree surface oxidation and roughness features. The possibility of the expulsion, oxidation and redeposition of molten droplets, leading to the formation of micron thick oxide layers, is related to bulk metal properties and the incident laser intensity. A correlation is found between the expulsion of molten droplets and a Reynolds number, showing the interaction is turbulent. The permanent effects of these interactions on metal surfaces are observed through scanning electron microscopy (SEM), transient calorimetric measurements and Fourier transform infrared (FTIR) spectroscopy. Observed surface textures are related to the scanning procedures used to irradiate the metal surface. Fundamental radiative properties of a metal surface, the total hemispherical emissivity, the near-normal spectral absorptivity, and others are examined in this study as they are affected by excimer laser radiation. It is determined that for heavily exposed Al surface, alpha' (10.6 microns) can be increased to values close to unity. Data relating to material removal rates and chemical surface modification for excimer laser radiation is also discussed. The resultant reduction in the near-normal reflectivity solves the fundamental problem of coupling laser radiation into highly reflective and conductive metals such as copper and aluminum. The

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

High power CO2 lasers and their applications in nuclear industry

International Nuclear Information System (INIS)

Nath, A.K.

2002-01-01

Carbon dioxide laser is one of the most popular lasers in industry for material processing applications. It has very high power capability and high efficiency, can be operated in continuous wave (CW), modulated and pulsed modes, and has relatively low cost. Due to these characteristics high power CO 2 lasers are being used worldwide in different industries for a wide variety of materials processing operations. In nuclear industry, CO 2 laser has made its way in many applications. Some of the tasks performed by multikilowatt CO 2 laser are cutting operations necessary to remove unprocessible hardware from reactor fuel assemblies, sealing/fixing/removing radioactive contaminations onto/from concrete surfaces and surface modification of engineering components for improved surface mechanical and metallurgical characteristics. We have developed various models of CW CO 2 lasers of power up to 12 kW and a high repetitive rate TEA (Transversely Excited Atmospheric pressure) CO 2 laser of 500 W average power operating at 500 Hz repetition rates. We have carried many materials processing applications of direct relevance to DAE. Recent work includes laser welding of end plug PFBR fuel tubes, martensitic stainless steel and titanium alloy, surface cladding of turbine blades made of Ni-super alloy with stellite 694, fabrication on graded material of stainless steel and stellite, and laser scabbling, drilling and cutting of concrete which have potential application in decontamination and decommissioning of nuclear facilities. A brief overview of these indigenous developments will be presented. (author)

A study of the formation of Cr-surface alloyed layer on structural alloy steel by Co2 laser

International Nuclear Information System (INIS)

Kim, T.H.; Han, W.S.

1986-01-01

In order to improve wear and erosion-resistances of a structural alloy steel (SNCM 8) during heat-cycling, chromium-alloyed layers were produced on the surface by irradiating Co 2 laser. Specimens were prepared either by electroplating of hard-chromium or coating of chromium powders on the steel followed by the laser treatment. Index values, which related the depth and the width of the alloyed layers to the scanning speed of laser, for both samples are experimentally measured. At a fixed scanning speed, while both samples resulted in a similar depth of the alloyed layers, the chromium powder coated specimen showed larger width of the alloyed layer than the chromium electroplated one. The hardness values of the alloyed layers in both samples were slightly lower than that of the martensitic region beneath the alloyed layers. But they are considerably higher than those of steel matrices. Regardless of the prior treatments before laser irradiation, distributions of chromium were fairly uniform throughout the alloyed layers. (Author)

Catalysts for long-life closed-cycle CO2 lasers

Science.gov (United States)

Schryer, David R.; Sidney, Barry D.; Miller, Irvin M.; Hess, Robert V.; Wood, George M.; Batten, Carmen E.; Burney, Lewis G.; Hoyt, Ronald F.; Paulin, Patricia A.; Brown, Kenneth G.

1987-01-01

Long-life, closed-cycle operation of pulsed CO2 lasers requires catalytic CO-O2 recombination both to remove O2, which is formed by discharge-induced CO2 decomposition, and to regenerate CO2. Platinum metal on a tin (IV) oxide substrate (Pt/SnO2) has been found to be an effective catalyst for such recombination in the desired temperature range of 25 to 100 C. This paper presents a description of ongoing research at NASA-LaRC on Pt/SnO2 catalyzed CO-O2 recombination. Included are studies with rare-isotope gases since rare-isotope CO2 is desirable as a laser gas for enhanced atmospheric transmission. Results presented include: (1) achievement of 98% to 100% conversion of a stoichiometric mixture of CO and O2 to CO2 for 318 hours (greater than 1 x 10 to the 6th power seconds), continuous, at a catalyst temperature of 60 C, and (2) development of a technique verified in a 30-hour test, to prevent isotopic scrambling when CO-18 and O-18(2) are reacted in the presence of a common-isotope Pt/Sn O-16(2) catalyst.

Research on interaction of laser light and non-metals. Evaluation of laser irradiation behavior to concrete

International Nuclear Information System (INIS)

Yamada, Tomonori; Muramatsu, Toshiharu

2015-02-01

In this study the response of hardened cement pastes, which are a major component of concrete, to laser irradiation was investigated under various experimental conditions aiming at the future application to “laser-processing” of concrete. (1) 75 tests were performed with combinations of following experimental conditions: (a) a water/cement ratio of the hardened cement pastes was either of 0.25, 0.30, or 0.35; (b) a laser power density was either of 100, 200, 300, 400, or 500 W/cm 2 ; and (c) laser irradiation duration was ranging from 1 to 40 seconds. It was found that hardened cement paste subjected to laser irradiation explodes very easily to be hollowed in all the experimental conditions; this response is applicable to “laser-drilling” of a hardened cement paste. The “laser-drilling” speeds up following to laser power increment or to irradiation time extension. It was also found that samples tend to melt rather than explode under the irradiation with a smaller laser power density (100 W/cm 2 ) at a high water/cement ratio (0.35). (2) Totally 75 laser irradiation tests for fixed mortar blocks were performed with combinations of following experimental conditions: (a) fine aggregate in the mortar blocks was either of quartz, limestone, or Nachiguro-ishi; (b) a laser power density was either of 100, 200, 300, 400, or 500 W/cm 2 ; and (c) laser irradiation duration was ranging from 0.2 to 40 seconds. Although it was found that all kinds of the mortar fuse under laser irradiation after all, difference in the response to laser irradiation among the mortars was also found; energy density required to fuse the mortar including limestone was larger than that required to fuse the mortar including quartz or Nachiguro-ishi. (author)

Effects of CO2 laser irradiation on the wettability and human skin fibroblast cell response of magnesia partially stabilised zirconia

International Nuclear Information System (INIS)

Hao, L.; Lawrence, J.

2003-01-01

Human skin fibroblast cells in vitro responses on the surface of a bioinert zirconia ceramic partially stabilised with magnesia partially stabilised zirconia (MgO-PSZ) bioinert ceramic before and after CO 2 laser treatment were investigated to find the interrelationship between the cell adhesion, wettability and laser parameters. Contact angle, θ, measurements of a set of test liquids were a clear indication that surface treatment of the MgO-PSZ with a CO 2 laser brought about a reduction in θ, indicating that the wettability of the MgO-PSZ had been enhanced. A relationship was found between the wettability and the microstructure of the MgO-PSZ surface and laser processing parameters. It was subsequently deduced that the factors active in causing the observed modification in the wettability of the MgO-PSZ were the increases in the surface O 2 content and the polar component of the surface energy, γ sv p , the latter resulting from surface melting and resolidification. Moreover, the investigation into the human skin fibroblast cell response revealed that the CO 2 laser treatment of the MgO-PSZ had resulted in a surface favourable for cell adhesion, as the extent of cell attachment and adhesion on the MgO-PSZ surface was enhanced depending on laser parameters. Such an improvement in cell adhesion, which could be greatly beneficial to developing enhanced bonding at the tissue and implant interface, was influenced by the surface properties of the modified MgO-PSZ, particular wettability

Possible applications of powerful pulsed CO2-Lasers in tokamak

International Nuclear Information System (INIS)

Nastoyashchii, A.F.; Morozov, I.N.; Hassanein, A.

1998-01-01

Applications of powerful pulsed CO 2 -lasers for injection of fuel tablets or creation of a protective screen from the vapor of light elements to protect against the destruction of plasma-facing components are discussed, and the corresponding laser parameters are determined. The possibility of using CO 2 -lasers in modelling the phenomena of powerful and energetic plasma fluxes interaction with a wall, as in the case of a plasma disruption, is considered. (author)

High-quality laser cutting of stainless steel in inert gas atmosphere by ytterbium fibre and CO2 lasers

International Nuclear Information System (INIS)

Golyshev, A A; Malikov, A G; Orishich, A M; Shulyat'ev, V B

2014-01-01

Processes of cutting stainless steel by ytterbium fibre and CO 2 lasers have been experimentally compared. The cut surface roughnesses for 3- and 5-mm-thick stainless steel sheets are determined. The absorption coefficient of laser radiation during cutting is measured. It is established that the power absorbed by metal during cutting by the CO 2 laser exceeds that for the ytterbium laser (provided that the cutting speed remains the same). The fact that the maximum cutting speed of the CO 2 laser is lower than that of the ytterbium fibre laser is explained. (laser technologies)

Sb2S3:C/CdS p-n junction by laser irradiation

International Nuclear Information System (INIS)

Arato, A.; Cardenas, E.; Shaji, S.; O'Brien, J.J.; Liu, J.; Castillo, G. Alan; Das Roy, T.K.; Krishnan, B.

2009-01-01

In this paper, we report laser irradiated carbon doping of Sb 2 S 3 thin films and formation of a p-n junction photovoltaic structure using these films. A very thin carbon layer was evaporated on to chemical bath deposited Sb 2 S 3 thin films of approximately 0.5 μm in thickness. Sb 2 S 3 thin films were prepared from a solution containing SbCl 3 and Na 2 S 2 O 3 at 27 deg. C for 5 h and the films obtained were highly resistive. These C/Sb 2 S 3 thin films were irradiated by an expanded laser beam of diameter approximately 0.5 cm (5 W power, 532 nm Verdi laser), for 2 min at ambient atmosphere. Morphology and composition of these films were analyzed. These films showed p-type conductivity due to carbon diffusion (Sb 2 S 3 :C) by the thermal energy generated by the absorption of laser radiation. In addition, these thin films were incorporated in a photovoltaic structure Ag/Sb 2 S 3 :C/CdS/ITO/Glass. For this, CdS thin film of 50 nm in thickness was deposited on a commercially available ITO coated glass substrate from a chemical bath containing CdCl 2 , sodium citrate, NH 4 OH and thiourea at 70 deg. C . On the CdS film, Sb 2 S 3 /C layers were deposited. This multilayer structure was subjected to the laser irradiation, C/Sb 2 S 3 side facing the beam. The p-n junction formed by p-Sb 2 S 3 :C and n-type CdS showed V oc = 500 mV and J sc = 0.5 mA/cm 2 under illumination by a tungsten halogen lamp. This work opens up a new method to produce solar cell structures by laser assisted material processing

QCL seeded, ns-pulse, multi-line, CO2 laser oscillator for laser-produced-plasma extreme-UV source

Science.gov (United States)

Nowak, Krzysztof Michał; Suganuma, Takashi; Kurosawa, Yoshiaki; Ohta, Takeshi; Kawasuji, Yasufumi; Nakarai, Hiroaki; Saitou, Takashi; Fujimoto, Junichi; Mizoguchi, Hakaru; Sumitani, Akira; Endo, Akira

2017-01-01

Successful merger of state-of-the-art, semiconductor quantum-cascade lasers (QCL), with the mature CO2 laser technology, resulted in a delivery of highly-desired qualities of CO2 laser output that were not available previously without much effort. These qualities, such as multi-line operation, excellent spectro-temporal stability and pulse waveform control, became available from a single device of moderate complexity. This paper describes the operation principle and the unique properties of the solid{state seeded CO2 laser, invented for an application in laser-produced-plasma (LPP), extreme-UV (EUV) light source.

BRIEF COMMUNICATIONS: Experimental study of the energy balance in the interaction of a pulsed CO2 laser with metal and insulating targets in air

Science.gov (United States)

Babaeva, N. A.; Vas'kovskiĭ, Yu M.; Rovinskiĭ, R. E.; Ryabinkina, V. A.

1991-09-01

Measurements were made of components of the energy balance in the interaction of pulsed CO2 laser radiation with Dural, glass, quartz, ebonite, and Plexiglas in air at atmospheric pressure. At laser energy densities between 1 and 20 J/cm2 and in the spectral range 0.2-7 μm, the re-emission of radiation by the laser plasma was found to be less than 1 %. At energy densities exceeding 10 J/cm2, up to 90% of the laser energy failed to reach the irradiated surface.

Effects of low intensity laser acupoint irradiation on inhibiting islet beta-cell apoptosis in rats with type 2 diabetes

Science.gov (United States)

Xiong, Guoxin; Xiong, Leilei; Li, Xinzhong

2016-09-01

To investigate the effects of low intensity semiconductor laser acupoint irradiation on inhibiting islet beta-cell apoptosis in rats with type 2 diabetes, a method using a high-fat diet and low-dose intraperitoneal injections of streptozotocin established a type 2 diabetes mellitus rat model. Model rats were randomly divided into a laser acupoint irradiation group, rosiglitazone control group, and placebo group; each group had 10 rats. In addition, 10 normal male rats were selected for the normal control group. The Housanli, Neiting and Yishu acupoints of the rats in the laser acupoint irradiation group were irradiated with a 10 mW semiconductor laser; each point was irradiated for 15 min, once every 2 d over 28 d, for a total of 14 episodes of irradiation. The rosiglitazone group rats were given rosiglitazone (0.2 mg kg-1) intragastrically; the placebo group rats were given 0.9% brine (0.2 mg kg-1) intragastrically, once daily, for four consecutive weeks. The change of fasting blood glucose was determined before and after each treatment. The islet beta-cell apoptosis was determined. The islet beta-cell apoptosis rates of the laser acupoint irradiation group and the rosiglitazone group were significantly lower than the rate of the placebo group. Even though the rate was lower in the laser acupoint irradiation group than in the rosiglitazone group, there was no significant difference between them. It is shown that acupoint irradiation with a semiconductor laser can effectively inhibit islet beta-cell apoptosis in rats with type 2 diabetes.

A 2.5-kW industrial CO2 laser

Science.gov (United States)

Golov, V. K.; Ivanchenko, A. I.; Krasheninnikov, V. V.; Ponomarenko, A. G.; Shepelenko, A. A.

1986-06-01

A fast-flow laser is reported in which the active medium is excited by a self-sustained dc discharge produced by an electric-discharge device with nonsectioned electrodes. In the laser, two discharge gaps are formed by a flat anode and two cathodes, one on each side of the anode. A gas mixture is driven through the gasdynamic channel by a centrifugal fan rotating at 6000 rpm/min. With a mixture of CO2:N2:He = 2.5:7.5:5 mm Hg, the rated power is 2.5 kW; the maximum power is 4 kW with the mixture 2.5:7.5:10 mm Hg. The general design of the laser is described, and its principal performance characteristics are given.

Diffraction efficiency enhancement of femtosecond laser-engraved diffraction gratings due to CO{sub 2} laser polishing

Energy Technology Data Exchange (ETDEWEB)

Choi, Hun-Kook [Gwangju Institute of Science and Technology, Gwangju (Korea, Republic of); Chosun University, Gwangju (Korea, Republic of); Jung, Deok; Sohn, Ik-Bu; Noh, Young-Chul; Lee, Yong-Tak [Gwangju Institute of Science and Technology, Gwangju (Korea, Republic of); Kim, Jin-Tae [Chosun University, Gwangju (Korea, Republic of); Ahsan, Shamim [Khulna University, Khulna (Bangladesh)

2014-11-15

This research demonstrates laser-assisted fabrication of high-efficiency diffraction gratings in fused-silica glass samples. Initially, femtosecond laser pulses are used to engrave diffraction gratings on the glass surfaces. Then, these micro-patterned glass samples undergo CO{sub 2} laser polishing process. unpolished diffraction gratings encoded in the glass samples show an overall diffraction efficiency of 18.1%. diffraction gratings imprinted on the glass samples and then polished four times by using a CO{sub 2} laser beam attain a diffraction efficiency of 32.7%. We also investigate the diffraction patterns of the diffraction gratings encoded on fused-silica glass surfaces. The proposed CO{sub 2} laser polishing technique shows great potential in patterning high-efficiency diffraction gratings on the surfaces of various transparent materials.

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

CO2 laser photo-induced decomposition of ammoniated ammonium ions

International Nuclear Information System (INIS)

Ikezoe, Yasumasa; Soga, Takesi; Suzuki, Kazuya; Moriyama, Noboru; Ohno, Shin-ichi

1995-01-01

Photo-induced decomposition of ammoniated (clustered) ammonium ions was studied using a CO 2 laser to excite vibrational levels of the cluster ion. A tandem mass spectrometer (TMS) was installed with two quadrupole mass filters, a corona discharge ionization chamber, and a series of einzel lenses. Cluster ions of NH 4 + ·nNH 3 with n=1-7 were formed in TMS, and found to decompose at the frequency of 1077 cm -1 to an extent in proportional to laser intensity. CO 2 laser between 925 and 1055 do not decompose the cluster ions with laser intensities examined. (author)

Laser irradiation of carbon–tungsten materials

International Nuclear Information System (INIS)

Marcu, A; Lungu, C P; Ursescu, D; Porosnicu, C; Grigoriu, C; Avotina, L; Kizane, G; Marin, A; Osiceanu, P; Grigorescu, C E A; Demitri, N

2014-01-01

Carbon–tungsten layers deposited on graphite by thermionic vacuum arc (TVA) were directly irradiated with a femtosecond terawatt laser. The morphological and structural changes produced in the irradiated area by different numbers of pulses were systematically explored, both along the spots and in their depths. Although micro-Raman and Synchrotron-x-ray diffraction investigations have shown no carbide formation, they have shown the unexpected presence of embedded nano-diamonds in the areas irradiated with high fluencies. Scanning electron microscopy images show a cumulative effect of the laser pulses on the morphology through the ablation process. The micro-Raman spatial mapping signalled an increased percentage of sp 3 carbon bonding in the areas irradiated with laser fluencies around the ablation threshold. In-depth x-ray photoelectron spectroscopy investigations suggested a weak cumulative effect on the percentage increase of the sp 2 -sp 3 transitions with the number of laser pulses just for nanometric layer thicknesses. (paper)

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...

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.

Modeling of UV laser-induced patterning of ultrathin Co films on bulk SiO2: verification of short- and long-range ordering mechanisms

Science.gov (United States)

Trice, Justin; Favazza, Christopher; Kalyanaraman, Ramki; Sureshkumar, R.

2006-03-01

Irradiating ultrathin Co films (1 to 10 nm) by a short-pulsed UV laser leads to pattern formation with both short- and long-range order (SRO, LRO). Single beam irradiation produces SRO, while two-beam interference irradiation produces a quasi-2D arrangement of nanoparticles with LRO and SRO. The pattern formation primarily occurs in the molten phase. An estimate of the thermal behavior of the film/substrate composite following a laser pulse is presented. The thermal behavior includes the lifetime of the liquid phase and the thermal gradient during interference heating. Based on this evidence, the SRO is attributed to spinodal dewetting of the film while surface tension gradients induced by the laser interference pattern appear to influence LRO [1]. [1] C.Favazza, J.Trice, H.Krishna, R.Sureshkumar, and R.Kalyanaraman, unpublished.

Biomodulatory effects of laser irradiation on dental pulp cells in vitro

Science.gov (United States)

Milward, Michael R.; Hadis, Mohammed A.; Cooper, Paul R.; Gorecki, Patricia; Carroll, James D.; Palin, William M.

2015-03-01

Low level laser/light therapy (LLLT) or photobiomodulation is a biophysical approach that can be used to reduce pain, inflammation and modulate tissue healing and repair. However, its application has yet to be fully realized for dental disease treatment. The aim of this study was to assess the modulation of dental pulp cell (DPC) responses using two LLLT lasers with wavelengths of 660nm and 810nm. Human DPCs were isolated and cultured in phenol-red-free α- MEM/10%-FCS at 37°C in 5% CO2. Central wells of transparent-based black walled 96-microplates were seeded with DPCs (passages 2-4; 150μL; 25,000 cell/ml). At 24h post-seeding, cultures were irradiated using a Thor Photomedicine LLLT device (THOR Photomedicine, UK) at 660nm (3, 6 or 13s to give 2, 5 and 10J/cm2) or 810nm (for 1, 2 or 5s to deliver 5, 10 and 20J/cm2). Metabolic activity was assessed via a modified MTT assay 24h post-irradiation. Statistical differences were identified using analysis of variance and post-hoc Tukey tests (P=0.05) and compared with nonirradiated controls. Significantly higher MTT activity was obtained for both lasers (P0.05). Consequently, enhanced irradiation parameters was apparent for both lasers. These parameters should be further optimised to identify the most effective for therapeutic application.

Analysis on the electron motion in the laser mixture CO/sub 2/-N/sub 2/-He-CO

Energy Technology Data Exchange (ETDEWEB)

Braglia, G L [Parma Univ. (Italy). Ist. di Fisica; Parma Univ. (Italy). Ist. di Matematica); Bruzzese, R [Naples Univ. (Italy). Ist. Elettrotecnico; Caraffini, G L [Parma Univ. (Italy). Ist. di Matematica

1979-06-02

An analysis of the electron motion in the laser mixture CO/sub 2/-N/sub 2/-He-CO (6:34:54:6) is presented. The transport coefficients are given as a function of E/N. Special attention is turned to the operating characteristics of the laser mixture. The results obtained from the Boltzmann equation are tested by the Monte-Carlo technique for E/N=1.5 10/sup -16/ and 5.0 10/sup -16/ (V cm/sup 2/).

Elevated CO2 increases photosynthesis in fluctuating irradiance regardless of photosynthetic induction state

NARCIS (Netherlands)

Kaiser, Elias; Zhou, Dianfan; Heuvelink, Ep; Harbinson, Jeremy; Morales Sierra, A.; Marcelis, Leo F.M.

2017-01-01

Leaves are often exposed to fluctuating irradiance, which limits assimilation. Elevated CO2 enhances dynamic photosynthesis (i.e. photosynthesis in fluctuating irradiance) beyond its effects on steady-state photosynthesis rates. Studying the role of CO2 in dynamic photosynthesis is important for

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.

Effects of CO{sub 2} laser irradiation on the wettability and human skin fibroblast cell response of magnesia partially stabilised zirconia

Energy Technology Data Exchange (ETDEWEB)

Hao, L.; Lawrence, J

2003-10-15

Human skin fibroblast cells in vitro responses on the surface of a bioinert zirconia ceramic partially stabilised with magnesia partially stabilised zirconia (MgO-PSZ) bioinert ceramic before and after CO{sub 2} laser treatment were investigated to find the interrelationship between the cell adhesion, wettability and laser parameters. Contact angle, {theta}, measurements of a set of test liquids were a clear indication that surface treatment of the MgO-PSZ with a CO{sub 2} laser brought about a reduction in {theta}, indicating that the wettability of the MgO-PSZ had been enhanced. A relationship was found between the wettability and the microstructure of the MgO-PSZ surface and laser processing parameters. It was subsequently deduced that the factors active in causing the observed modification in the wettability of the MgO-PSZ were the increases in the surface O{sub 2} content and the polar component of the surface energy, {gamma}{sub sv}{sup p}, the latter resulting from surface melting and resolidification. Moreover, the investigation into the human skin fibroblast cell response revealed that the CO{sub 2} laser treatment of the MgO-PSZ had resulted in a surface favourable for cell adhesion, as the extent of cell attachment and adhesion on the MgO-PSZ surface was enhanced depending on laser parameters. Such an improvement in cell adhesion, which could be greatly beneficial to developing enhanced bonding at the tissue and implant interface, was influenced by the surface properties of the modified MgO-PSZ, particular wettability.

INTERACTION OF RADIATION WITH MATTER. LASER PLASMA: Increase in the amplitude of hf currents during exposure of a neutral target to microsecond CO2 laser pulses

Science.gov (United States)

Antipov, A. A.; Losev, Leonid L.; Meshalkin, E. A.

1988-09-01

High-frequency electric currents were generated by irradiation of a metal target with CO2 laser pulses. It was found that the region where the ambient gas was photoionized had a decisive influence on the hf current amplitude. A method for increasing the amplitude of the current by creating an auxiliary laser jet on the target was proposed and used. An hf current of up to 1 A amplitude was observed at a frequency of 75 MHz and this current lasted for 1.5 μs.

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.

Effect of CO2 low-intensity laser in reducing pain in orthodontics and ortho-dontic tooth movement%CO2弱激光照射对减轻正畸疼痛及牙齿移动速度的影响

Institute of Scientific and Technical Information of China (English)

韩晶莹; 朱晓红; 侯录; 李鹍

2013-01-01

目的：探讨不同能量参数CO2弱激光局部照射对尖牙向远中移动过程中牙齿疼痛及牙齿移动速度的影响。方法选择60例拔牙矫正的错合畸形患者，在牙列排齐整平后，使用0.018英寸不锈钢圆丝，用链状皮圈以150 g力量拉上颌尖牙向远中移动的过程中以两种不同强度能量参数的CO2弱激光对右侧尖牙根部区域进行照射，左侧作为对照侧。使用视觉模拟评分法（ VAS）评价CO2弱激光局部照射对牙齿疼痛程度的影响。用游标卡尺测量尖牙远移的距离和支抗丧失（第一磨牙近中移动距离）的程度，评价两种能量参数CO2弱激光局部照射对尖牙向远中移动的过程中牙齿移动速度的影响。结果两种能量参数均能减轻正畸牙齿疼痛程度。高能量参数组激光能有效地加快牙齿移动速度，而低能量参数组没有明显加速牙齿的移动速度。结论不同能量参数的CO2弱激光局部照射对减轻正畸牙齿疼痛程度及牙齿移动速度的影响不同。%Objective To explore the effects of different energy parameters of CO 2 low-intensity laser in reducing orthodontic pain and tooth movement during canine distal movement .Meth-ods Sixty patients were included .After the dentition aligned , 0.018 inch stainless steel round wire was used , the device for canine distal movement was elastomeric chain which produced o-riginally 150 g force, the right canine root area was irradiated by two different energy parame-ters of CO2 low laser, the left was control group .The impact of the CO 2 low-intensity laser local irradiation on the patients ’ level of pain was evaluated with the visual analog scale ( VAS ) . The distance of canine to molar was measured with a vernier caliper , efect of two kinds of ener-gy parameters of CO 2 low laser irradiation on the distal movement of the canine tooth movement speed was evaluated .Results The two energy parameters of CO 2 low laser

Vacuum laser acceleration using a radially polarized CO sub 2 laser beam

CERN Document Server

Liu, Y; He, P

1999-01-01

Utilizing the high-power, radially polarized CO sub 2 laser and high-quality electron beam at the Brookhaven Accelerator Test Facility, a vacuum laser acceleration scheme is proposed. In this scheme, optics configuration is simple, a small focused beam spot size can be easily maintained, and optical damage becomes less important. At least 0.5 GeV/m acceleration gradient is achievable by 1 TW laser power.

Temporal and spatial temperature distribution in the glabrous skin of rats induced by short-pulse CO2 laser

Science.gov (United States)

Lu, Pen-Li; Hsu, Shu-Shen; Tsai, Meng-Li; Jaw, Fu-Shan; Wang, An-Bang; Yen, Chen-Tung

2012-11-01

Pain is a natural alarm that aids the body in avoiding potential danger and can also present as an important indicator in clinics. Infrared laser-evoked potentials can be used as an objective index to evaluate nociception. In animal studies, a short-pulse laser is crucial because it completes the stimulation before escape behavior. The objective of the present study was to obtain the temporal and spatial temperature distributions in the skin caused by the irradiation of a short-pulse laser. A fast speed infrared camera was used to measure the surface temperature caused by a CO2 laser of different durations (25 and 35 ms) and power. The measured results were subsequently implemented with a three-layer finite element model to predict the subsurface temperature. We found that stratum corneum was crucial in the modeling of fast temperature response, and escape behaviors correlated with predictions of temperature at subsurface. Results indicated that the onset latency and duration of activated nociceptors must be carefully considered when interpreting physiological responses evoked by infrared irradiation.

High-quality laser cutting of stainless steel in inert gas atmosphere by ytterbium fibre and CO{sub 2} lasers

Energy Technology Data Exchange (ETDEWEB)

Golyshev, A A; Malikov, A G; Orishich, A M; Shulyat' ev, V B [S.A. Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation)

2014-03-28

Processes of cutting stainless steel by ytterbium fibre and CO{sub 2} lasers have been experimentally compared. The cut surface roughnesses for 3- and 5-mm-thick stainless steel sheets are determined. The absorption coefficient of laser radiation during cutting is measured. It is established that the power absorbed by metal during cutting by the CO{sub 2} laser exceeds that for the ytterbium laser (provided that the cutting speed remains the same). The fact that the maximum cutting speed of the CO{sub 2} laser is lower than that of the ytterbium fibre laser is explained. (laser technologies)

New technique for the direct analysis of food powders confined in a small hole using transversely excited atmospheric CO(2) laser-induced gas plasma.

Science.gov (United States)

Khumaeni, Ali; Ramli, Muliadi; Deguchi, Yoji; Lee, Yong Inn; Idris, Nasrullah; Kurniawan, Koo Hendrik; Lie, Tjung Jie; Kagawa, Kiichiro

2008-12-01

Taking advantage of the differences between the interactions of transversely excited atmospheric (TEA) CO(2) lasers with metal and with organic powder, a new technique for the direct analysis of food powder samples has been developed. In this technique, the powder samples were placed into a small hole with a diameter of 2 mm and a depth of 3 mm and covered by a metal mesh. The TEA CO(2) laser (1500 mJ, 200 ns) was focused on the powder sample surfaces, passing through the metal mesh, at atmospheric pressure in nitrogen gas. It is hypothesized that the small hole functions to confine the powder particles and suppresses the blowing-off of sample, while the metal mesh works as the source of electrons to initiate the strong gas breakdown plasma. The confined powder particles are then ablated by laser irradiation and the ablated particles move into the strong gas breakdown plasma region to be atomized and excited; this method cannot be applied for the case of Nd:YAG lasers because in such case the metal mesh itself was ablated by the laser irradiation. A quantitative analysis of a milk powder sample containing different concentrations of Ca was successfully demonstrated, resulting in a good linear calibration curve with high precision.

Possible applications of powerful pulsed CO2-lasers in tokamak reactors

International Nuclear Information System (INIS)

Nastoyashchii, A.F.; Morozov, I.N.; Hassanein, A.

1998-01-01

Applications of powerful pulsed CO 2 -lasers for injection of fuel tablets or creation of a protective screen from the vapor of light elements to protect against the destruction of plasma-facing components are discussed, and the corresponding laser parameters are determined. The possibility of using CO 2 -lasers in modeling the phenomena of powerful and energetic plasma fluxes interaction with a wall, as in the case of a plasma disruption, is considered

Ablative skin resurfacing with a novel microablative CO2 laser.

Science.gov (United States)

Gotkin, Robert H; Sarnoff, Deborah S; Cannarozzo, Giovanni; Sadick, Neil S; Alexiades-Armenakas, Macrene

2009-02-01

Carbon dioxide (CO2) laser skin resurfacing has been a mainstay of facial rejuvenation since its introduction in the mid 1990s. Recently, a new generation of fractional or microablative CO2 lasers has been introduced to the marketplace. According to the concept of fractional photothermolysis, these lasers ablate only a fraction of the epidermal and dermal architecture in the treatment area. An array of microscopic thermal wounds is created that ablates the epidermis and dermis within very tiny zones; adjacent to these areas, the epidermis and dermis are spared. This microablative process of laser skin resurfacing has proven safe and effective not only for facial rejuvenation, but elsewhere on the body as well. It is capable of improving wrinkles, acne scars, and other types of atrophic scars and benign pigmented lesions associated with elastotic, sun-damaged skin. Because of the areas of spared epidermis and dermis inherent in a procedure that employs fractional photothermolysis, healing is more rapid compared to fully ablative CO2 laser skin resurfacing and downtime is proportionately reduced. A series of 32 consecutive patients underwent a single laser resurfacing procedure with the a new microablative CO2 laser. All patients were followed for a minimum of 6 months and were asked to complete patient satisfaction questionnaires; a 6 month postoperative photographic evaluation by an independent physician, not involved in the treatment, was also performed. Both sets of data were graded and reported on a quartile scale. Results demonstrated greater than 50% improvement in almost all patients with those undergoing treatment for wrinkles, epidermal pigment or solar elastosis deriving the greatest change for the better (>75%).

Interaction of CO2 laser-modified nylon with osteoblast cells in relation to wettability

International Nuclear Information System (INIS)

Waugh, D.G.; Lawrence, J.; Morgan, D.J.; Thomas, C.L.

2009-01-01

It has been amply demonstrated previously that CO 2 lasers hold the ability to surface modify various polymers. In addition, it has been observed that these surface enhancements can augment the biomimetic nature of the laser irradiated materials. This research has employed a CO 2 laser marker to produce trench and hatch topographical patterns with peak heights of around 1 μm on the surface of nylon 6,6. The patterns generated have been analysed using white light interferometry, optical microscopy and X-ray photoelectron spectroscopy was employed to determine the surface oxygen content. Contact angle measurements were used to characterize each sample in terms of wettability. Generally, it was seen that as a result of laser processing the contact angle, surface roughness and surface oxygen content increased whilst the apparent polar and total surface energies decreased. The increase in contact angle and reduction in surface energy components was found to be on account of a mixed intermediate state wetting regime owing to the change in roughness due to the induced topographical patterns. To determine the biomimetic nature of the modified and as-received control samples each one was seeded with 2 x 10 4 cells/ml normal human osteoblast cells and observed after periods of 24 h and 4 days using optical microscopy and SEM to determine mean cell cover densities and variations in cell morphology. In addition, a haemocytometer was used to show that the cell count for the laser patterned samples had increased by up to a factor of 1.5 compared to the as-received control sample after 4 days of incubation. Significantly, it was determined that all laser-induced patterns gave rise to better cell response in comparison to the as-received control sample studied due to increased preferential cell growth on those surfaces with increased surface roughness.

Power stabilized CO2 gas transport laser

International Nuclear Information System (INIS)

Foster, J.D.; Kirk, R.F.; Moreno, F.E.; Ahmed, S.A.

1975-01-01

The output power of a high power (1 kW or more) CO 2 gas transport laser is stabilized by flowing the gas mixture over copper plated baffles in the gas channel during operation of the laser. Several other metals may be used instead of copper, for example, nickel, manganese, palladium, platinum, silver and gold. The presence of copper in the laser gas circuit stabilizes output power by what is believed to be a compensation of the chemical changes in the gas due to the cracking action of the electrical discharge which has the effect of diminishing the capactiy of the carbon dioxide gas mixture to maintain the rated power output of the laser. (U.S.)

CO2 Laser Market

Science.gov (United States)

Simonsson, Samuel

1989-03-01

It gives me a great deal of pleasure to introduce our final speaker of this morning's session for two reasons: First of all, his company has been very much in the news not only in our own community but in the pages of Wall Street Journal and in the world economic press. And, secondly, we would like to welcome him to our shores. He is a temporary resident of the United States, for a few months, forsaking his home in Germany to come here and help with the start up of a new company which we believe, probably, ranks #1 as the world supplier of CO2 lasers now, through the combination of former Spectra Physics Industrial Laser Division and Rofin-Sinar GMBH. Samuel Simonsson is the Chairman of the Board of Rofin-Sinar, Inc., here in the U.S. and managing director of Rofin-Sinar GMBH. It is a pleasure to welcome him.

Research on catalysts for long-life closed-cycle CO2 laser oaperation

Science.gov (United States)

Sidney, Barry D.; Schryer, David R.; Upchurch, Billy T.; Hess, Robert V.; Wood, George M.

1987-01-01

Long-life, closed-cycle operation of pulsed CO2 lasers requires catalytic CO-O2 recombination both to remove O2, which is formed by discharge-induced CO2 decomposition, and to regenerate CO2. Platinum metal on a tin-oxide substrate (Pt/SnO2) has been found to be an effective catalyst for such recombination in the desired temperature range of 25 to 100 C. This paper presents a description of ongoing research at NASA-Langley on Pt/SnO2 catalyzed CO-O2 recombination. Included are studies with rare-isotope gases since rare-isotope CO2 is desirable as a laser gas for enhanced atmospheric transmission. Results presented include: (1) the effects of various catalyst pretreatment techniques on catalyst efficiency; (2) development of a technique, verified in a 30-hour test, to prevent isotopic scrambling when C(O-18) and (O-18)2 are reacted in the presence of a common-isotope Pt/Sn(O-16)2 catalyst; and (3) development of a mathematical model of a laser discharge prior to catalyst introduction.

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 CO 2 (Manual Fractional Technology, MFT) and, a second pass, with fractional CO 2 . The MFT with fractional CO 2 lasers to treat hypertrophic scars is evaluated. A total of 158 patients with hypertrophic scars had three sessions of MFT with fractional CO 2 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 (Plaser drilling by MFT and a fractional CO2 laser had profound effects on the hypertrophic scars treated. It works by increasing the penetration depth of the CO 2 laser in the scar tissue, exerting more precise effects on the hypertrophic scars. MFT combined with fractional CO 2 laser has the potential to be a major advance in the treatment of hypertrophic scars. © 2017 Wiley Periodicals, Inc.

Helios, a 20 TW CO2 laser fusion facility

International Nuclear Information System (INIS)

Ladish, J.S.

1979-01-01

Since June 1978 the Los Alamos Scientific Laboratory's Helios CO 2 laser fusion facility has been committed to an experimental target program to investigate the feasibility of laser produced inertial confinement fusion. This system is briefly described, and preliminary experimental results are reported

Comparative study of Nd:YAG laser-induced breakdown spectroscopy and transversely excited atmospheric CO2 laser-induced gas plasma spectroscopy on chromated copper arsenate preservative-treated wood.

Science.gov (United States)

Khumaeni, Ali; Lie, Zener Sukra; Niki, Hideaki; Lee, Yong Inn; Kurihara, Kazuyoshi; Wakasugi, Motoomi; Takahashi, Touru; Kagawa, Kiichiro

2012-03-01

Taking advantage of the specific characteristics of a transversely excited atmospheric (TEA) CO(2) laser, a sophisticated technique for the analysis of chromated copper arsenate (CCA) in wood samples has been developed. In this study, a CCA-treated wood sample with a dimension of 20 mm × 20 mm and a thickness of 2 mm was attached in contact to a nickel plate (20 mm × 20 mm × 0.15 mm), which functions as a subtarget. When the TEA CO(2) laser was successively irradiated onto the wood surface, a hole with a diameter of approximately 2.5 mm was produced inside the sample and the laser beam was directly impinged onto the metal subtarget. Strong and stable gas plasma with a very large diameter of approximately 10 mm was induced once the laser beam had directly struck the metal subtarget. This gas plasma then interacted with the fine particles of the sample inside the hole and finally the particles were effectively dissociated and excited in the gas plasma region. By using this technique, high precision and sensitive analysis of CCA-treated wood sample was realized. A linear calibration curve of Cr was successfully made using the CCA-treated wood sample. The detection limits of Cr, Cu, and As were estimated to be approximately 1, 2, and 15 mg/kg, respectively. In the case of standard LIBS using the Nd:YAG laser, the analytical intensities fluctuate and the detection limit was much lower at approximately one-tenth that of TEA CO(2) laser. © 2012 Optical Society of America

Method for measuring energy-input inhomogeneities in electroionization CO/sub 2/-lasers

Energy Technology Data Exchange (ETDEWEB)

Borovkov, V V; Kornilov, V G; Sukhanov, L V; Chelpanov, V I

1987-08-01

A Michelson interferometer at a wavelength of 0.63 micron was used to measure optical inhomogeneities due to variations of the polarizability of the molecular components in CO/sub 2/-laser mixtures under vibrational excitation in a nonself-sustained electric discharge. It is suggested that the observed effect can be used for the noninertial and noncontact diagnostics of energy-input distribution over the cross section of the active medium of an electroionization CO/sub 2/-laser. Results are presented for N/sub 2/-He, CO/sub 2/-He, CO/sub 2/-N/sub 2/-He, and CO/sub 2/-He mixtures. 10 references.

Direct writing Eu3+-doped Ba2TiSi2O8 crystalline pattern by femtosecond laser irradiation

International Nuclear Information System (INIS)

Zhu Bin; Dai Ye; Ma Hongliang; Zhang Songmin; Qiu Jianrong

2008-01-01

A femtosecond laser with 800 nm, 250 kHz and 150 fs has been used to irradiate Eu 3+ -doped BaO-TiO 2 -SiO 2 glasses. It is found from micro-Raman spectra and optical microscope that crystalline dots and lines are formed around the focal point of the femtosecond laser beam. Both blue emission at 400 nm due to the second harmonic generation and red emission due to the transitions of Eu 3+ are observed from the irradiation region with the precipitation of Ba 2 TiSi 2 O 8 crystal. The mechanism of the observed phenomenon is discussed

Modematic: a fast laser beam analyzing system for high power CO2-laser beams

Science.gov (United States)

Olsen, Flemming O.; Ulrich, Dan

2003-03-01

The performance of an industrial laser is very much depending upon the characteristics of the laser beam. The ISO standards 11146 and 11154 describing test methods for laser beam parameters have been approved. To implement these methods in industry is difficult and especially for the infrared laser sources, such as the CO2-laser, the availabl analyzing systems are slow, difficult to apply and having limited reliability due to the nature of the detection methods. In an EUREKA-project the goal was defined to develop a laser beam analyzing system dedicated to high power CO2-lasers, which could fulfill the demands for an entire analyzing system, automating the time consuming pre-alignment and beam conditioning work required before a beam mode analyses, automating the analyzing sequences and data analysis required to determine the laser beam caustics and last but not least to deliver reliable close to real time data to the operator. The results of this project work will be described in this paper. The research project has led to the development of the Modematic laser beam analyzer, which is ready for the market.

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.

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.

CO2 laser milling of hard tissue

Science.gov (United States)

Werner, Martin; Ivanenko, Mikhail; Harbecke, Daniela; Klasing, Manfred; Steigerwald, Hendrik; Hering, Peter

2007-02-01

Drilling of bone and tooth tissue belongs to recurrent medical procedures (screw- and pin-bores, bores for implant inserting, trepanation etc.). Small round bores can be in general quickly produced with mechanical drills. Problems arise however by angled drilling, by the necessity to fulfill the drilling without damaging of sensitive soft tissue beneath the bone, or by the attempt to mill precisely noncircular small cavities. We present investigations on laser hard tissue "milling", which can be advantageous for solving these problems. The "milling" is done with a CO2 laser (10.6 μm) with pulse duration of 50 - 100 μs, combined with a PC-controlled galvanic beam scanner and with a fine water-spray, which helps to avoid thermal side-effects. The damaging of underlying soft tissue can be prevented through control of the optical or acoustical ablation signal. The ablation of hard tissue is accompanied with a strong glowing, which is absent during the laser beam action on soft tissue. The acoustic signals from the diverse tissue types exhibit distinct differences in the spectral composition. Also computer image analysis could be a useful tool to control the operation. Laser "milling" of noncircular cavities with 1 - 4 mm width and about 10 mm depth is particularly interesting for dental implantology. In ex-vivo investigations we found conditions for fast laser "milling" of the cavities without thermal damage and with minimal tapering. It included exploration of different filling patterns (concentric rings, crosshatch, parallel lines and their combinations), definition of maximal pulse duration, repetition rate and laser power, optimal position of the spray. The optimized results give evidences for the applicability of the CO2 laser for biologically tolerable "milling" of deep cavities in the hard tissue.

The osmotic fragility of human erythrocytes is inhibited by laser irradiation

International Nuclear Information System (INIS)

Habodaszova, D.; Sikurova, L.; Waczulikova, I.

2004-01-01

In this study we investigated the influence of green laser irradiation (532 nm, 30 mW, 31,7 J/cm 2 ) on the membrane integrity of human erythrocytes and compared the results with the effect of infrared laser irradiation (810 nm, 50 mW, 31,3 J/cm 2 ). To evaluate the membrane integrity of erythrocytes, one clinical parameter, the osmotic fragility, was investigated. We observed a decrease in osmotic fragility of the erythrocytes after irradiation by the green laser light as well as by the infrared laser compared to non-irradiated controls (Authors)

Low-power laser irradiation did not stimulate breast cancer cells following ionizing radiation

Science.gov (United States)

Silva, C. R.; Camargo, C. F. M.; Cabral, F. V.; Ribeiro, M. S.

2016-03-01

Cancer has become a public health problem worldwide. Radiotherapy may be a treatment to a number of types of cancer, frequently using gamma-radiation with sources such as 137Cs and 60Co, with varying doses, dose rates, and exposure times to obtain a better as a stimulant for cell proliferation and tissue healing process. However, its effects on cancer cells are not yet well elucidated. The purpose of this work was to evaluate the effects of the LPL on breast cancer cultures after ionizing radiation. The breast cancer-MDA-MB-231 cells were gamma irradiated by a 60Co source, with dose of 2.5 Gy. After 24h, cells were submitted to LPL irradiation using a red laser emitting at λ= 660 nm, with output power of 40 mW and exposure time of 30 s and 60 s. The plates were uniformly irradiated, with energy of 1.2 J and 2.4 J, respectively. Cell viability was analyzed using the exclusion method with trypan blue. Our results show that breast cancer cells submitted to LPL after ionizing radiation remained 95 % viable. No statistically significant differences were observed between laser and control untreated cells, (P > 0.05). These findings suggest that LPL did not influenced cancer cells viability.

Criteria for formation of low-frequency sound under wide-aperture repetitively pulsed laser irradiation of solids

International Nuclear Information System (INIS)

Tishchenko, V N; Posukh, V G; Gulidov, A I; Zapryagaev, V I; Pavlov, A A; Boyarintsev, Ye L; Golubev, M P; Kavun, I N; Melekhov, A V; Golobokova, L S; Miroshnichenko, I B; Pavlov, Al A; Shmakov, A S

2011-01-01

The criteria for merging shock waves formed by optical breakdowns on the surface of solids have been investigated. Targets made of different materials were successively irradiated by two CO 2 -laser pulses with energies up to 200 J and a duration of ∼1 μs. It is shown that the criteria under consideration can be applied to different targets and irradiation regimes and make it possible to calculate the parameters of repetitively pulsed laser radiation that are necessary to generate low-frequency sound and ultrasound in air.

State of the art of CO laser angioplasty system

Science.gov (United States)

Arai, Tsunenori; Mizuno, Kyoichi; Miyamoto, Akira; Sakurada, Masami; Kikuchi, Makoto; Kurita, Akira; Nakamura, Haruo; Takaoka, Hidetsugu; Utsumi, Atsushi; Takeuchi, Kiyoshi

1994-07-01

A unique percutaneous transluminal coronary angioplasty system new IR therapy laser with IR glass fiber delivery under novel angioscope guidance was described. Carbon monoxide (CO) laser emission of 5 mm in wavelength was employed as therapy laser to achieve precise ablation of atheromatous plaque with a flexible As-S IR glass fiber for laser delivery. We developed the first medical CO laser as well as As-S IR glass fiber cable. We also developed 5.5 Fr. thin angioscope catheter with complete directional manipulatability at its tip. The system control unit could manage to prevent failure irradiations and fiber damages. This novel angioplasty system was evaluated by a stenosis model of mongrel dogs. We demonstrated the usefulness of our system to overcome current issues on laser angioplasty using multifiber catheter with over-the-guidewire system.

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...

Osteogenesis differentiation of human periodontal ligament cells by CO2 laser-treatment stimulating macrophages via BMP2 signalling pathway

International Nuclear Information System (INIS)

Hsieh, Wen-Hui; Chen, Yi-Jyun; Hung, Chi-Jr; Huang, Tsui-Hsien; Kao, Chia-Tze; Shie, Ming-You

2014-01-01

Immune reactions play an important role in determining the biostimulation of bone formation, either in new bone formation or inflammatory fibrous tissue encapsulation. Macrophage cell, the important effector cells in the immune reaction, which are indispensable for osteogenesis and their heterogeneity and plasticity, render macrophages a primer target for immune system modulation. However, there are very few studies about the effects of macrophage cells on laser treatment-regulated osteogenesis. In this study, we used CO 2 laser as a model biostimulation to investigate the role of macrophage cells on the CO 2 laser stimulated osteogenesis. Bone morphogenetic protein 2 (BMP2) was also significantly up regulated by the CO 2 laser stimulation, indicating that macrophage may participate in the CO 2 laser stimulated osteogenesis. Interestingly, when laser treatment macrophage-conditioned medium were applied to human periodontal ligament cells (hPDLs), the osteogenesis differentiation of hPDLs was significantly enhanced, indicating the important role of macrophages in CO 2 laser-induced osteogenesis. These findings provided valuable insights into the mechanism of CO 2 laser-stimulated osteogenic differentiation, and a strategy to optimize the evaluation system for the in vitro osteogenesis capacity of laser treatment. (paper)

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

KAUST Repository

Fan, Yiqiang; Li, Huawei; Foulds, Ian G.

2011-01-01

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

Control of laser pulse waveform in longitudinally excited CO2 laser by adjustment of excitation circuit

Science.gov (United States)

Uno, Kazuyuki; Jitsuno, Takahisa

2018-05-01

In a longitudinally excited CO2 laser that had a 45 cm-long discharge tube with a 1:1:2 mixture of CO2/N2/He gas at a pressure of 3.0 kPa, we realized the generation of a short laser pulse with a spike pulse width of about 200 ns and a pulse tail length of several tens of microseconds, control of the energy ratio of the spike pulse part to the pulse tail part in the short laser pulse, the generation of a long laser pulse with a pulse width of several tens of microseconds, and control of the pulse width in the long laser pulse, by using four types of excitation circuits in which the capacitance was adjusted. In the short laser pulse, the energy ratio was in the range 1:14-1:112. In the long laser pulse, the pulse width was in the range 25.7-82.7 μs.

Single mode operation of a TEA CO2 laser

International Nuclear Information System (INIS)

Wada, Kazuhiro; Tunawaki, Yoshiaki; Yamanaka, Masanobu.

1993-01-01

Single mode operation of a TEA CO 2 laser was performed by using an optical system of Fox-Smith type. Laser beam was taken out from the cavity by using a beam splitter, and was reflected by a mirror back to the cavity. By inserting a Fabry-Perot etalon between the splitter and the mirror, beat of laser pulses can be removed completly. (author)

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...

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....

Automation methodology for the development of LPFG using CO2 laser radiation

Science.gov (United States)

Castro Alves, D.; Coelho, João. M. P.; Nespereira, Marta; Monteiro, Fernando; Abreu, Manuel; Rebordão, J. M.

2013-11-01

The mid-infrared radiation produced by CO2 lasers is being widely used to produce long period fiber gratings (LPFG) with several advantages over other methods. Several techniques can be used to irradiate the fiber in order to produce the necessary effect. Using a cylindrical lens to create a line of light or scanning of a spot over the fiber are the most common approaches. Usually, the period is produced either by a translation stage moving perpendicular to the incident beam or by using a two mirrors scanner that inscribes the entire period directly on the fiber. In both cases, the synchronization between the laser and the moving elements is critical. Also, when using a two mirrors scanner, the dimension of the LPFG is limited by the focusing lens diameter and its focal length. All this become critical when one needs to increase the LPFG's length or reduce its period. The later usually implies shorter laser emission times, which is limited by the laser emission physics (at least for cheap low power CW lasers). In order to overcome the disadvantages of each method, a combined approach is presented and analyzed. A mirror scans vertically the beam over a cylindrical lens and a translation stage moves the fiber to create the different periods. The laser keeps emitting during the complete process increasing laser power stability and thus, improving grating homogeneity. To guarantee the synchronization between the translation table and the one mirror scanner, special hardware and software was created.

Responses of C4 grasses to atmospheric CO2 enrichment : I. Effect of irradiance.

Science.gov (United States)

Sionit, Nasser; Patterson, David T

1984-12-01

The growth and photosynethetic responses to atmospheric CO 2 enrichment of 4 species of C 4 grasses grown at two levels of irradiance were studied. We sought to determine whether CO 2 enrichment would yield proportionally greater growth enhancement in the C 4 grasses when they were grown at low irradiance than when grown at high irradiance. The species studied were Echinochloa crusgalli, Digitaria sanguinalis, Eleusine indica, and Setaria faberi. Plants were grown in controlled environment chambers at 350, 675 and 1,000 μl 1 -1 CO 2 and 1,000 or 150 μmol m -2 s -1 photosynthetic photon flux density (PPFD). An increase in CO 2 concentration and PPFD significantly affected net photosynthesis and total biomass production of all plants. Plants grown at low PPFD had significantly lower rates of photosynthesis, produced less biomass, and had reduced responses to increases in CO 2 . Plants grown in CO 2 -enriched atmosphere had lower photosynthetic capacity relative to the low CO 2 grown plants when exposed to lower CO 2 concentration at the time of measurement, but had greater rate of photosynthesis when exposed to increasing PPFD. The light level under which the plants were growing did not influence the CO 2 compensation point for photosynthesis.

二氧化碳弱激光照射减轻正畸治疗疼痛的临床研究%Clinical studies of CO2 laser in reducing pain in orthodontics

Institute of Scientific and Technical Information of China (English)

韩晶莹; 刘丽媛; 展望; 陆晓丽; 周珊; 贾莉

2011-01-01

Objective To investigate the effect of local CO2 laser irradiation on orthodontic pain for the patients with firstarch wires. Methods 60 patients wearing fixed appliance were included in this study, 34 patients accepted local CO2laser irradiation and 26 patients as a control group.Patients were then instructed to rate their levels of pain on a visualanalog scale over time. Results The level of orthodontic pain in local CO2 laser irradiation group were significantly lowerthan the control group. Conclusion Local CO2 laser irradiation will reduce pain associated with orthodontic forceapplication.%目的:探讨C02弱激光局部照射减轻正畸治疗疼痛的临床效果.方法:选择60例固定矫治患者,激光照射组34例、对照组26例,使用视觉模拟评分法(VAS)评价C02激光局部照射在矫治初始弓丝放置后不同时间点患者的疼痛程度.结果:应用C02弱激光局部照射组患者的正畸疼痛程度明显低于对照组患者.结论:C02激光局部照射可以减轻固定矫治患者治疗过程中的疼痛.

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.

Accelerator mass spectrometry 14C determination in CO2 produced from laser decomposition of aragonite.

Science.gov (United States)

Rosenheim, Brad E; Thorrold, Simon R; Roberts, Mark L

2008-11-01

The determination of (14)C in aragonite (CaCO(3)) decomposed thermally to CO(2) using an yttrium-aluminum-garnet doped neodymium laser is reported. Laser decomposition accelerator mass spectrometry (LD-AMS) measurements reproduce AMS determinations of (14)C from the conventional reaction of aragonite with concentrated phosphoric acid. The lack of significant differences between these sets of measurements indicates that LD-AMS radiocarbon dating can overcome the significant fractionation that has been observed during stable isotope (C and O) laser decomposition analysis of different carbonate minerals. The laser regularly converted nearly 30% of material removed into CO(2) despite it being optimized for ablation, where laser energy breaks material apart rather than chemically altering it. These results illustrate promise for using laser decomposition on the front-end of AMS systems that directly measure CO(2) gas. The feasibility of such measurements depends on (1) the improvement of material removal and/or CO(2) generation efficiency of the laser decomposition system and (2) the ionization efficiency of AMS systems measuring continuously flowing CO(2).

Structure and properties of optical-discharge plasma in CO2-laser beam near target surface

Science.gov (United States)

Danshchikov, Ye. V.; Dymshakov, V. A.; Lebedev, F. V.; Ryazanov, A. V.

1986-05-01

An experimental study of optical-discharge plasma in a CO2-laser beam at a target surface was made for the purpose of exploring the not yet understood role of this plasma in the laser-target interaction process. Such a plasma was produced by means of a quasi-continuous CO2-laser with an unstable resonator, its power being maintained constant for 1 ms periods. Its radiation was focused on the surfaces of thick and seeding thin Al, Ti, and Ta targets inclined at an approximately 70 deg. angle to the beam, inside a hermetic chamber containing air, argon, or helium under atmospheric pressure. The radiation intensity distribution over the focal plane and the nearest caustic surface in the laser beam was measured along with the plasma parameters, the latter by the methods of spectral analysis and photoelectric recording. The instrumentation for this purpose included an MDR-3 monochromator with an entrance slit, a double electron-optical converter, a memory oscillograph, and an SI-10-30 ribbon lamp as radiation reference standard. The results yielded integral diametral intensity distributions of the emission lines Ti-II (457.2 nm), Ti-I (464 nm), Ar-II (462 nm), radial and axial temperature profiles of optical discharge in metal vapor in surrounding gas, and the radial temperature profile of irradiated metal surface at successive instants of time. The results reveal marked differences between the structures and the properties of optical-discharge plasma in metal vapor and in surrounding gas, optical discharge in the former being characterized by localization within the laser beam and optical discharge in the latter being characterized by a drift away from the target.

13CO2/12CO2 isotope ratio analysis in human breath using a 2 μm diode laser

Science.gov (United States)

Sun, Mingguo; Cao, Zhensong; Liu, Kun; Wang, Guishi; Tan, Tu; Gao, Xiaoming; Chen, Weidong; Yinbo, Huang; Ruizhong, Rao

2015-04-01

The bacterium H. pylori is believed to cause peptic ulcer. H. pylori infection in the human stomach can be diagnosed through a CO2 isotope ratio measure in exhaled breath. A laser spectrometer based on a distributed-feedback semiconductor diode laser at 2 μm is developed to measure the changes of 13CO2/12CO2 isotope ratio in exhaled breath sample with the CO2 concentration of ~4%. It is characterized by a simplified optical layout, in which a single detector and associated electronics are used to probe CO2 spectrum. A new type multi-passes cell with 12 cm long base length , 29 m optical path length in total and 280 cm3 volume is used in this work. The temperature and pressure are well controlled at 301.15 K and 6.66 kPa with fluctuation amplitude of 25 mK and 6.7 Pa, respectively. The best 13δ precision of 0.06o was achieved by using wavelet denoising and Kalman filter. The application of denoising and Kalman filter not only improved the signal to noise ratio, but also shorten the system response time.

Nano-pulsed laser irradiation scanning system for phase-change materials

International Nuclear Information System (INIS)

Kim, Sookyung; Li Xuezhe; Lee, Sangbin; Kim, Kyung-Ho; Lee, Seung-Yop

2008-01-01

Recently, the demand of a laser irradiation tester is increasing for phase change random access memory (PRAM) as well as conventional optical storage media. In this study, a nano-pulsed laser irradiation system is developed to characterize the optical property and writing performance of phase-change materials, based on a commercially available digital versatile disk (DVD) optical pick-up. The precisely controlled focusing and scanning on the material's surface are implemented using the auto-focusing mechanism and a voice coil motor (VCM) of the commercial DVD pick-up. The laser irradiation system provides various writing and reading functions such as adjustable laser power, pulse duration, recording pattern (spot, line and area), and writing/reading repetition, phase transition, and in situ reflectivity measurement before/after irradiation. Measurements of power time effect (PTE) diagram and reflectivity map of Ge 2 Sb 2 Te 5 samples show that the proposed laser irradiation system provides the powerful scanning tool to quantify the optical characteristics of phase-change materials

Research on industrial 10kW CO2 laser achieves major breakthrough

Science.gov (United States)

1991-01-01

The industrial 10kW CO2 laser is one of the items which the industrially developed nations are competing to develop. This laser is capable of continuous output power of over 10kW and can operate continuously for more than 6 hours. The 10kW CO2 laser developed as a key task of China's 7th Five-Year Plan and all its technological targets such as output power, electrooptical conversion efficiency and primary charging continuous operating time, have reached the level of world advancement, allowing China to enter the ranks of international advancement in the area of laser technology. The industrial 10kW CO2 laser can have wide application in such areas of industry as heat treating, machining, welding and surface treatment in industries such as steel, automobiles, ship building and aircraft manufacturing. For instance, using the high-efficiency laser beams of this 10kW laser to treat rollers, fan blades and automotive cylinder blocks can increase the life of these parts and produce large economic benefits. At present, industrial tests of gear welding is already being done on this 10kW laser.

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....

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.

Particularities of interaction of CO sub 2 -laser radiation with oxide materials

CERN Document Server

Salikhov, T P

2002-01-01

The results of experimental investigation of vapor phase influence on the interaction parameters of the infrared laser radiation with oxide materials (Al sub 2 O sub 3 , ZrO sub 2 , CeO sub 2) have been presented. A phenomenon of laser radiation by the samples investigated under laser heating has been experimentally discovered for the first time. This phenomenon connected with forming of the stable vapor shell above the irradiated samples was expressed as a sharp drop in temperature on the heating curve and called as an absorption flash. (author)

Novel CO2 laser robotic controller outperforms experienced laser operators in tasks of accuracy and performance repeatability.

Science.gov (United States)

Wong, Yu-Tung; Finley, Charles C; Giallo, Joseph F; Buckmire, Robert A

2011-08-01

To introduce a novel method of combining robotics and the CO(2) laser micromanipulator to provide excellent precision and performance repeatability designed for surgical applications. Pilot feasibility study. We developed a portable robotic controller that appends to a standard CO(2) laser micromanipulator. The robotic accuracy and laser beam path repeatability were compared to six experienced users of the industry standard micromanipulator performing the same simulated surgical tasks. Helium-neon laser beam video tracking techniques were employed. The robotic controller demonstrated superiority over experienced human manual micromanipulator control in accuracy (laser path within 1 mm of idealized centerline), 97.42% (standard deviation [SD] 2.65%), versus 85.11% (SD 14.51%), P = .018; and laser beam path repeatability (area of laser path divergence on successive trials), 21.42 mm(2) (SD 4.35 mm(2) ) versus 65.84 mm(2) (SD 11.93 mm(2) ), P = .006. Robotic micromanipulator control enhances accuracy and repeatability for specific laser tasks. Computerized control opens opportunity for alternative user interfaces and additional safety features. Copyright © 2011 The American Laryngological, Rhinological, and Otological Society, Inc.

Effect of semiconductor GaAs laser irradiation on pain perception in mice

Energy Technology Data Exchange (ETDEWEB)

Zarkovic, N.; Manev, H.; Pericic, D.; Skala, K.; Jurin, M.; Persin, A.; Kubovic, M.

1989-01-01

The influence of subacute exposure (11 exposures within 16 days) of mice to the low power (GaAs) semiconductive laser-stimulated irradiation on pain perception was investigated. The pain perception was determined by the latency of foot-licking or jumping from the surface of a 53 degrees C hot plate. Repeated hot-plate testing resulted in shortening of latencies in both sham- and laser-irradiated mice. Laser treatment (wavelength, 905 nm; frequency, 256 Hz; irradiation time, 50 sec; pulse duration, 100 nsec; distance, 3 cm; peak irradiance, 50 W/cm2 in irradiated area; and total exposure, 0.41 mJ/cm2) induced further shortening of latencies, suggesting its stimulatory influence on pain perception. Administration of morphine (20 mg/kg) prolonged the latency of response to the hot plate in both sham- and laser-irradiated mice. This prolongation tended to be lesser in laser-irradiated animals. Further investigations are required to elucidate the mechanism of the observed effect of laser.

Morphological Changes Of The Root Surface And Fracture Resistance After Treatment Of Root Fracture By CO2 Laser And Glass Ionomer Or Mineral Trioxide Aggregates

Science.gov (United States)

Badr, Y. A.; Abd El-Gawad, L. M.; Ghaith, M. E.

2009-09-01

This in vitro study evaluates the morphological changes of the root surface and fracture resistance after treatment of root cracks by CO2 laser and glass Ionomer or mineral trioxide aggregates (MTA). Fifty freshly extracted human maxillary central incisor teeth with similar dimension were selected. Crowns were sectioned at the cemento-enamel junction, and the lengths of the roots were adjusted to 13 mm. A longitudinal groove with a dimension of 1×5 mm2 and a depth of 1.5 mm was prepared by a high speed fissure bur on the labial surface of the root. The roots were divided into 5 groups: the 10 root grooves in group 1 were remained unfilled and were used as a control group. The 10 root grooves in group 2 were filled with glass Ionomer, 10 root grooves in group 3 were filled with MTA, the 10 root grooves in group 4 were filled with glass Ionomer and irradiated by CO2 laser and the 10 root grooves in group 5 were filled with MTA and irradiated with CO2 laser. Scanning electron microscopy was performed for two samples in each group. Tests for fracture strength were performed using a universal testing machine and a round tip of a diameter of 4 mm. The force was applied vertically with a constant speed of 1 mm min 1. For each root, the force at the time of fracture was recorded in Newtons. Results were evaluated statistically with ANOVA and Turkey's Honestly Significant Difference (HSD) tests. SEM micrographs revealed that the melted masses and the plate-like crystals formed a tight Chemical bond between the cementum and glass Ionomer and melted masses and globular like structure between cementum and MTA. The mean fracture resistance was the maximum fracture resistance in group 5 (810.8 N). Glass Ionomer and MTA with the help of CO2 laser can be an alternative to the treatment of tooth crack or fracture. CO2 laser increase the resistance of the teeth to fracture.

Hologaphy of a CO2 laser generated plasma

International Nuclear Information System (INIS)

Elkerbout, A.C.H.; Van Dijk, J.W.; Donaldson, T.P.

1976-01-01

An expermental technique for generating holographic interferograms is discussed and illustrated with results obtained on a plasma generated by a 75 J CO 2 laser pulse incident at intensities of approximately 9 x 10 12 W/cm 2 on a plane carbon target. (author)

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 CO 2 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 CO 2 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 CO 2 lasers, in combination with topical betamethasone solution and NB-UVB, was suitable for stable non-segmental vitiligo. For vitiligo, the ablative fractional CO 2 laser is more effective than the non-ablative fractional laser.

Influence of irradiation conditions on plasma evolution in laser-surface interaction

Science.gov (United States)

Hermann, J.; Boulmer-Leborgne, C.; Dubreuil, B.; Mihailescu, I. N.

1993-09-01

The plasma plume induced by pulsed CO2 laser irradiation of a Ti target at power densities up to 4×108 W cm-2 was studied by emission spectroscopy. Time- and space-resolved measurements were performed by varying laser intensity, laser temporal pulse shape, ambient gas pressure, and the nature of the ambient gas. Experimental results are discussed by comparison with usual models. We show that shock wave and plasma propagation depend critically on the ratio Ivap/Ii, Ivap being the intensity threshold for surface vaporization and Ii the plasma ignition threshold of the ambient gas. Spectroscopic diagnostics of the helium breakdown plasma show maximum values of electron temperature and electron density in the order of kTe˜10 eV and ne=1018 cm-3, respectively. The plasma cannot be described by local thermodynamic equilibrium modeling. Nevertheless, excited metal atoms appear to be in equilibrium with electrons, hence, they can be used like a probe to measure the electron temperature. In order to get information on the role of the plasma in the laser-surface interaction, Ti surfaces were investigated by microscopy after irradiation. Thus an enhanced momentum transfer from the plasma to the target due to the recoil pressure of the breakdown plasma could be evidenced.

CO2 laser-aided waste incineration

International Nuclear Information System (INIS)

Costes, J.R.; Guiberteau, P.; Caminat, P.; Bournot, P.

1994-01-01

Lasers are widely employed in laboratories and in certain industrial applications, notably for welding, cutting and surface treatments. This paper describes a new application, incineration, which appears warranted when the following features are required: high-temperature incineration (> 1500 deg C) with close-tolerance temperature control in an oxidizing medium while ensuring containment of toxic waste. These criteria correspond to the application presented here. Following a brief theoretical introduction concerning the laser/surface interaction, the paper describes the incineration of graphite waste contaminated with alpha-emitting radionuclides. Process feasibility has been demonstrated on a nonradioactive prototype capable of incinerating 10 kg -h-1 using a 7 kW CO 2 laser. An industrial facility with the same capacity, designed to operate within the constraints of an alpha-tight glove box environment, is now at the project stage. Other types of applications with similar requirements may be considered. (authors). 3 refs., 7 figs

Synergistic effect of fluoride and laser irradiation for the inhibition of the demineralization of dental enamel

Science.gov (United States)

Lee, Raymond; Chan, Kenneth H.; Jew, Jamison; Simon, Jacob C.; Fried, Daniel

2017-02-01

Both laser irradiation and fluoride treatment alone are known to provide increased resistance to acid dissolution. CO2 lasers tuned to a wavelength of 9.3 μm can be used to efficiently convert the carbonated hydroxyapatite of enamel to a much more acid resistant purer phase hydroxyapatite (HAP). Further studies have shown that fluoride application to HAP yields fluoroapatite (FAP) which is even more resistant against acid dissolution. Previous studies show that CO2 lasers and fluoride treatments interact synergistically to provide significantly higher protection than either method alone, but the mechanism of interaction has not been elucidated. We recently observed the formation of microcracks or a "crazed" zone in the irradiated region that is resistant to demineralization using high-resolution microscopy. The microcracks are formed due to the slight contraction of enamel due to transformation of carbonated hydroxyapatite to the more acid resistant pure phase hydroxyapatite (HAP) that has a smaller lattice. In this study, we test the hypothesis that these small cracks will provide greater adhesion for topical fluoride for greater protection against acid demineralization.

Proton- and x-ray beams generated by ultra-fast CO2 lasers for medical applications

Science.gov (United States)

Pogorelsky, Igor; Polyanskiy, Mikhail; Yakimenko, Vitaly; Ben-Zvi, Ilan; Shkolnikov, Peter; Najmudin, Zulfikar; Palmer, Charlotte A. J.; Dover, Nicholas P.; Oliva, Piernicola; Carpinelli, Massimo

2011-05-01

Recent progress in using picosecond CO2 lasers for Thomson scattering and ion-acceleration experiments underlines their potentials for enabling secondary radiation- and particle- sources. These experiments capitalize on certain advantages of long-wavelength CO2 lasers, such as higher number of photons per energy unit, and favorable scaling of the electrons' ponderomotive energy and critical plasma density. The high-flux x-ray bursts produced by Thomson scattering of the CO2 laser off a counter-propagating electron beam enabled high-contrast, time-resolved imaging of biological objects in the picosecond time frame. In different experiments, the laser, focused on a hydrogen jet, generated monoenergetic proton beams via the radiation-pressure mechanism. The strong power-scaling of this regime promises realization of proton beams suitable for laser-driven proton cancer therapy after upgrading the CO2 laser to sub-PW peak power. This planned improvement includes optimizing the 10-μm ultra-short pulse generation, assuring higher amplification in the CO2 gas under combined isotopic- and power-broadening effects, and shortening the postamplification pulse to a few laser cycles (150-200 fs) via chirping and compression. These developments will move us closer to practical applications of ultra-fast CO2 lasers in medicine and other areas.

Independent CO2 loop for cooling the samples irradiated in the RA reactor vertical experimental channels, Task 2.50.05

International Nuclear Information System (INIS)

Stojic, M.; Pavicevic, M.

1964-01-01

This report contains the following volumes V and VI of the Project 'Independent CO 2 loop for cooling the samples irradiated in RA reactor vertical experimental channels': Design project of the dosimetry control system in the independent CO 2 loop for cooling the samples irradiated in the RA reactor vertical experimental channels, and Safety report for the Independent CO 2 loop for cooling the samples irradiated in the RA reactor vertical experimental channels [sr

Effect of laser irradiation on the structural, morphological and electrical properties of polycrystalline TiO2 thin films

Directory of Open Access Journals (Sweden)

M.I. Khan

Full Text Available TiO2 thin film is deposited on glass substrate by sol-gel dip coating technique. After deposition, films were irradiated by continuous wave (CW diode laser at an angle of 45°. XRD shows both the anatase and brookite phases of TiO2. Nano particles of regular and control sizes are appeared in SEM micrographs. Therefore, shape and size of nano particles can be control by using Laser irradiation. The average sheet resistivity of TiO2 thin film irradiated by 0, 2, 4 and 6 min are 6.72 × 105, 5.32 × 105, 3.44 × 105 and 4.95 × 105 (ohm-m respectively, according to four point probe. Keywords: TiO2, Diode laser, XRD, SEM

SiC interlayer by laser-cladding on WC-Co substrates for CVD diamond deposition

Energy Technology Data Exchange (ETDEWEB)

Contin, Andre; Fraga, Mariana Amorim; Vieira, Jose; Trava-Airoldi, Vladimir Jesus; Corat, Evaldo Jose, E-mail: andrecontin@yahoo.com.br [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil); Campos, Raonei Alves [Universidade Federal do Sul e Sudeste do Para (UNIFESSPA), Belem, PA (Brazil); Vasconcelos, Getulio [Instituto de Estudos Avancados (IEA), Sao Jose dos Campos, SP (Brazil)

2016-07-01

Full text: Despite their huge industrial potential and commercial interest, the direct diamond coating on cemented carbide (WC-Co) is limited, mainly because of the catalytic effect of Cobalt (Co) and the high difference in thermal expansion coefficient [1]. This results in poor adherence between diamond and WC-Co. In addition, the low diamond film adhesion to the cemented carbide useless for machining applications. Removal of Co binder from the substrate surface by superficial etching is one of the techniques used to improve the adhesion between diamond and WC-Co. For the present study, diamond films were deposited on WC-Co substrates with an intermediate barrier to block the Co diffusion to the surface substrate. The laser cladding process produced the SiC barrier, in which a powder layer is melted by a laser irradiation to create the coating on the substrate. The use of laser cladding is the novel method for an intermediate barrier for cemented carbides. The advantages of laser cladding include a faster processing speed, precision, versatility. We reported the application of pretreatment method called ESND (Electrostatic self-assembly seeding of nanocrystalline diamond). The nucleation density was around 10{sup 11}part/cm{sup 2}. Diamond films were grown by Hot Filament Chemical Vapor Deposition. Characterization of samples included Field Emission Gun-Scanning Electron Microscopy (FEG-SEM), Energy Dispersive X-ray (EDX), X-ray diffraction (XRD) and Raman Scattering Spectroscopy. Results showed that laser irradiation formed stable Co compounds in the interfacial barrier. It is because nucleation and good quality of diamond film since the cobalt are no longer free to migrate to the surface during the CVD diamond deposition. Reference: [1] Y. X. Cui, B. Shen, F. H. Sun. Diamond deposition on WC–Co substrate with amorphous SiC interlayer, Surface Engineering, 30, (2014) 237-243. (author)

Water vapor-nitrogen absorption at CO2 laser frequencies

Science.gov (United States)

Peterson, J. C.; Thomas, M. E.; Nordstrom, R. J.; Damon, E. K.; Long, R. K.

1979-01-01

The paper reports the results of a series of pressure-broadened water vapor absorption measurements at 27 CO2 laser frequencies between 935 and 1082 kaysers. Both multiple traversal cell and optoacoustic (spectrophone) techniques were utilized together with an electronically stabilized CW CO2 laser. Comparison of the results obtained by these two methods shows remarkable agreement, indicating a precision which has not been previously achieved in pressure-broadened studies of water vapor. The data of 10.59 microns substantiate the existence of the large (greater than 200) self-broadening coefficients determined in an earlier study by McCoy. In this work, the case of water vapor in N2 at a total pressure of 1 atm has been treated.

Effect of Irradiation Parameters on Morphology of Polishing DF2 (AISI-O1 Surface by Nd:YAG Laser

Directory of Open Access Journals (Sweden)

Wei Guo

2007-01-01

Full Text Available Pulse Nd:YAG laser was used to polish DF2 cold work steel. Influence of irradiation parameters on the 3D surface morphology was studied by 3D profilometer, scanning electron microscopy (SEM, and atomic force microscope (AFM. Results among the tests showed when DF2 specimens were irradiated with parameters of (i laser input energy P=1 J, (ii pulse feedrate=300 mm/min, (iii pulse duration (PD =3 milliseconds, and (iv pulse frequency f=20∼25 Hz, laser polishing of DF2 cold work steel seemed to be successful.

Absorption homogenization at wavy melt films by CO{sub 2}-lasers in contrast to 1 μm-wavelength lasers

Energy Technology Data Exchange (ETDEWEB)

Kaplan, Alexander F.H., E-mail: alexander.kaplan@ltu.se

2015-02-15

Highlights: • The absorption distribution of 1 μm wavelength lasers compared to 10 μm CO{sub 2}-lasers across a wavy molten steel surface is calculated, at grazing angle of incidence. • For a wide range of surface waviness parameters the CO{sub 2}-laser shows a much more homogenizing absorption behaviour than 1 μm-lasers. • Although the interaction is very complex and non-linear, it is fundamental and very distinct between CO{sub 2}-lasers and 1 μm-lasers, due to their very different Fresnel-absorption characteristics. • The strong local absorption peaks for 1 μm-lasers can cause very strong local boiling and amplification of surface waves, in good correlation to empirical experimental trends. • Such differences can in turn have strong consequences during laser materials processing like laser keyhole welding, laser drilling or laser remote fusion cutting. - Abstract: For wavy metal melts, across a wide range of their topology parameters, lasers with about 1 μm wavelength experience the highest Fresnel absorption around the shoulders of the waves. Calculations show that this induces a strong peak of the absorbed power density of the laser beam. The high temperature gradients have the potential to cause very local boiling and growth of the valleys. In contrast, for a certain parameter category the small Brewster angle for the CO{sub 2}-laser partially homogenizes the temperatures by elevated absorption at domains of grazing incidence. This has the potential to cause opposite consequences on the process, like wave smoothing.

High efficiency pump combiner fabricated by CO2 laser splicing system

Science.gov (United States)

Zhu, Gongwen

2018-02-01

High power combiners are of great interest for high power fiber lasers and fiber amplifiers. With the advent of CO2 laser splicing system, power combiners are made possible with low manufacturing cost, low loss, high reliability and high performance. Traditionally fiber optical components are fabricated with flame torch, electrode arc discharge or filament heater. However, these methods can easily leave contamination on the fiber, resulting inconsistent performance or even catching fire in high power operations. The electrodes or filaments also degrade rapidly during the combiner manufacturing process. The rapid degradation will lead to extensive maintenance, making it unpractical or uneconomic for volume production. By contrast, CO2 laser is the cleanest heating source which provides reliable and repeatable process for fabricating fiber optic components including high power combiners. In this paper we present an all fiber end pumped 7x1 pump combiner fabricated by CO2 laser splicing system. The input pump fibers are 105/125 (core/clad diameters in μm) fibers with a core NA of 0.22. The output fiber is a 300/320 fiber with a core NA of 0.22. The average efficiency is 99.4% with all 7 ports more than 99%. The process is contamination-free and highly repeatable. To our best knowledge, this is the first report in the literature on power combiners fabricated by CO2 laser splicing system. It also has the highest reported efficiency of its kind.

Effects of electrocautery, CO/sub 2/ laser, and contact Nd:YAG laser scalpel on the healing of intestinal incision

Energy Technology Data Exchange (ETDEWEB)

Puolakkainen, P.; Brackett, K.; Sankar, M.Y.; Joffe, S.; Schroeder, T.

1987-01-01

Leakage after intestinal resection is a serious complication with a high mortality rate. A recent study claims that cutting the intestine with the CO/sub 2/ laser improves the healing of intestinal anastomoses. The present study was undertaken to analyze the effects of electrocautery, CO/sub 2/ laser, and contact Nd:YAG laser on the healing of intestinal incisions. Fifteen piglets were used and the cutting and reanastomosing were performed by using all cutting methods in each animal in randomized order. Resection sites were 50 cm, 100 cm, and 150 cm distal to the ligament of Treitz. On the seventh day the bursting pressures were measured for each anastomosis. They were 172 +/- 17 mmHg for normal bowel segment and 133 +/- 12, 135 +/- 40, and 139 +/- 17 mmHg for electrocautery, CO/sub 2/ laser, and Nd:YAG laser, respectively. There were no mortality, no anastomotic leaks, and no statistically significant differences in the bursting pressures, in histology, or in the healing of anastomotic sites, indicating that electrocautery, CO/sub 2/ laser, and contact Nd:YAG laser scalpel can safely be used in the surgery of small intestine.

Tritium-doping enhancement of polystyrene by ultraviolet laser and hydrogen plasma irradiation for laser fusion experiments

Energy Technology Data Exchange (ETDEWEB)

Iwasa, Yuki, E-mail: iwasa-y@ile.osaka-u.ac.jp [Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871 (Japan); Yamanoi, Kohei; Iwano, Keisuke; Empizo, Melvin John F.; Arikawa, Yasunobu; Fujioka, Shinsuke; Sarukura, Nobuhiko; Shiraga, Hiroyuki; Takagi, Masaru; Norimatsu, Takayoshi; Azechi, Hiroshi [Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871 (Japan); Noborio, Kazuyuki; Hara, Masanori; Matsuyama, Masao [Hydrogen Isotope Research Center, Organization for Promotion of Research, University of Toyama, 3190 Gofuku, Toyama 930-8555 (Japan)

2016-11-15

Highlights: • Tritium-doped polystyrene films are fabricated by the Wilzbach method with UV laser and hydrogen plasma irradiation. • The 266-nm laser-irradiated, 355-nm laser-irradiated, and hydrogen plasma-irradiated polystyrene films exhibit higher PSL intensities and specific radioactivities than the non-irradiated sample. • Tritium doping by UV laser irradiation can be largely affected by the laser wavelength because of polystyrene’s absorption. • Hydrogen plasma irradiation results to a more uniform doping concentration even at low partial pressure and short irradiation time. • UV laser and plasma irradiations can be utilized to fabricate tritium-doped polystyrene shell targets for future laser fusion experiments. - Abstract: We investigate the tritium-doping enhancement of polystyrene by ultraviolet (UV) laser and hydrogen plasma irradiation. Tritium-doped polystyrene films are fabricated by the Wilzbach method with UV laser and hydrogen plasma. The 266-nm laser-irradiated, 355-nm laser-irradiated, and hydrogen plasma-irradiated polystyrene films exhibit higher PSL intensities and specific radioactivities than the non-irradiated sample. Tritium doping by UV laser irradiation can be largely affected by the laser wavelength because of polystyrene’s absorption. In addition, UV laser irradiation is more localized and concentrated at the spot of laser irradiation, while hydrogen plasma irradiation results to a more uniform doping concentration even at low partial pressure and short irradiation time. Both UV laser and plasma irradiations can nevertheless be utilized to fabricate tritium-doped polystyrene targets for future laser fusion experiments. With a high doping rate and efficiency, a 1% tritium-doped polystyrene shell target having 7.6 × 10{sup 11} Bq g{sup −1} specific radioactivity can be obtained at a short period of time thereby decreasing tritium consumption and safety management costs.

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

Compact transversely excited atmospheric (TEA) CO2 lasers (Marchetti et al 1983) find numerous scientific and technical applications. These include pulsed laser deposition (PLD). (Sankur et al 1988), photo-chemistry (Baranov 1983), lidar (Killinger & Menyuk 1981), optical pumping of molecular lasers (Midorikawa et al ...

60Co-labeling in 59Co(n,γ)60Co reaction and γ-ray irradiation of [Co(dien)2]3+ and [Co(en)3]3+ in crystals and/or in polyvinyl alcohol

International Nuclear Information System (INIS)

Sasaki, K.; Iiyoshi, N.; Watanabe, J.; Yamatera, H.

1982-01-01

Three isomers (sym-fac, unsym-fac, and mer forms) of [Co(dien) 2 ]Cl 3 were irradiated in a reactor in the form of crystals and in amorphous solids, where the ions were dissolved in polyvinyl alcohol (PVA) or adsorbed on an SP-Sephadex ion exchanger. The distribution of produced 60 Co among the isomers of the Co(III) complex and the Co(II) species was determined. The preferential labeling on the parent isomer was observed in crystals but not in PVA. In the Sephadex, no marked labeling occurred. For comparison with reactor-irradiated samples, mixed solutions of [Co(dien) 2 ]Cl 3 and 60 Co-labeled cobalt (II) chloride dissolved in PVA films ([Co(III)]/[Co(II)] = 2 - 3) were irradiated by γ-rays. Significant labeling was observed after the irradiation. Comparison of the results from the above experiments showed that the labeling was enhanced by radiation chemical reactions, and that the preferential labeling on the parent isomer of crystal samples resulted from the stiffness of the crystal matrix. (orig.)

Acute effects of pulsed-laser irradiation on the arterial wall

Science.gov (United States)

Nakamura, Fumitaka; Kvasnicka, Jan; Lu, Hanjiang; Geschwind, Herbert J.; Levame, Micheline; Bousbaa, Hassan; Lange, Francoise

1992-08-01

Pulsed laser coronary angioplasty with an excimer or a holmium-yttrium-aluminum-garnet (Ho:YAG) laser may become an alternative treatment for patients with coronary artery disease. However, little is known about its acute consequences on the normal arterial wall. This study was designed to examine the acute histologic consequences of these two pulsed lasers on the arterial wall of normal iliac arteries in rabbits. Irradiation with each laser was performed in 15 normal iliac sites on eight male New Zealand white rabbits. The excimer laser was operated at 308 nm, 25 Hz, 50 mJ/mm2/pulse, and 135 nsec/pulse and the Ho:YAG laser was operated at 2.1 micrometers , 3/5 Hz, 400 mJ/pulse, and 250 microsecond(s) ec/pulse. The excimer and Ho:YAG laser were coupled into a multifiber wire-guided catheter of 1.4 and 1.5 mm diameter, respectively. The sites irradiated with excimer or Ho:YAG laser had the same kinds of histologic features, consisting of exfoliation of the endothelium, disorganization of internal elastic lamina, localized necrosis of vascular smooth muscle cells, and fissures in the medial layer. However, the sites irradiated with excimer laser had lower grading scores than those irradiated with Ho:YAG laser (p vascular injury.

Early Regenerative Modifications of Human Postmenopausal Atrophic Vaginal Mucosa Following Fractional CO2 Laser Treatment

Directory of Open Access Journals (Sweden)

Stefano Salvatore

2018-01-01

Full Text Available BACKGROUND: Postmenopausal women experience undesired symptoms that adversely affect their quality of life. In the recent years, a specific 12 - week fractional CO2 laser treatment has been introduced, with highly significant relief of symptoms. AIM: The aim of this paper is the identification of the early modifications of structural components of atrophic vaginal mucosa induced by laser irradiation, which is responsible for the restorative processes. MATERIAL AND METHODS: We investigated by microscopical, ultrastructural and biochemical methods the modifications of the structural components of postmenopausal atrophic vaginal mucosa tissues after 1 hour following a single fractional laser CO2 application. RESULTS: In one hour, the mucosal epithelium thickens, with the maturation of epithelial cells and desquamation at the epithelial surface. In the connective tissue, new papillae indenting the epithelium with newly formed vessels penetrating them, new thin fibrils of collagen III are also formed in a renewed turnover of components due to the increase of metalloproteinase - 2. Specific features of fibroblasts support stimulation of their activity responsible of the renewal of the extracellular matrix, with an increase of mechanical support as connective tissue and stimulation of growth and maturation to epithelium thanks to new vessels and related factors delivered. CONCLUSION: We found the activation of regenerative mechanisms expressed both in the connective tissue - with the formation of new vessels, new papillae, and new collagen - and in the epithelium with the associated thickening and desquamation of cells at the mucosal surface.

CO2-laser-assisted processing of glass fiber-reinforced thermoplastic composites

Science.gov (United States)

Brecher, Christian; Emonts, Michael; Schares, Richard Ludwig; Stimpfl, Joffrey

2013-02-01

To fully exploit the potential of fiber-reinforced thermoplastic composites (FRTC) and to achieve a broad industrial application, automated manufacturing systems are crucial. Investigations at Fraunhofer IPT have proven that the use of laser system technology in processing FRTC allows to achieve high throughput, quality, flexibility, reproducibility and out-of-autoclave processing simultaneously. As 90% of the FRP in Europe1 are glass fiber-reinforced a high impact can be achieved by introducing laser-assisted processing with all its benefits to glass fiber-reinforced thermoplastics (GFRTC). Fraunhofer IPT has developed the diode laser-assisted tape placement (laying and winding) to process carbon fiber-reinforced thermoplastic composites (CFRTC) for years. However, this technology cannot be transferred unchanged to process milky transparent GFRTC prepregs (preimpregnated fibers). Due to the short wavelength (approx. 980 nm) and therefore high transmission less than 20% of the diode laser energy is absorbed as heat into non-colored GFRTC prepregs. Hence, the use of a different wave length, e.g. CO2-laser (10.6 μm) with more than 90% laser absorption, is required to allow the full potential of laser-assisted processing of GFRTC. Also the absorption of CO2-laser radiation at the surface compared to volume absorption of diode laser radiation is beneficial for the interlaminar joining of GFRTC. Fraunhofer IPT is currently developing and investigating the CO2-laser-assisted tape placement including new system, beam guiding, process and monitoring technology to enable a resource and energy efficient mass production of GFRP composites, e.g. pipes, tanks, masts. The successful processing of non-colored glass fiber-reinforced Polypropylene (PP) and Polyphenylene Sulfide (PPS) has already been proven.

Absorption of CO2 laser light by a dense, high temperature plasma

International Nuclear Information System (INIS)

Peacock, N.J.; Forrest, M.J.; Morgan, P.D.; Offenberger, A.A.

1977-01-01

The interaction between a pulsed, CO 2 laser beam and the plasma produced in a plasma focus device is investigated theoretically and experimentally. The CO 2 laser radiation, directed orthogonal to the pinch axis and along the density gradient only weakly perturbs the focus since the radiation density of 30 J cm -3 (allowing for the Airy enhancement factor near the critical layer), is still less than the plasma thermal energy >=1 kJ cm -3 . On the contrary, the CO 2 laser beam is grossly affected by the plasma and absorption during the compressed pinch phase when the plasma frequency is much more complete than can be predicted by classical resistivity. Density fluctuations at the Langmuir frequency are measured directly for forward scattering from a probe, ruby laser beam. Since the wave numbers correspond to approximately 0.1 the Langmuir waves should appear as electron 'lines' in the scattered spectrum shifted by 427 A from the ruby laser wavelength. At low CO 2 laser pump intensity the electron wave intensity is close to the thermal level. As the pump is increased beyond a threshold of approximately 3x10 9 W/cm -2 (in vacuo) enhanced scattering is observed, reaching a factor of 30 above thermal. A WKB treatment of the electron-ion decay instability which takes into account the linear growth of waves at equal electron and ion temperatures and their convection in an inhomogeneous plasma is reasonably consistent with the observations

LASERS: A cryogenic slab CO laser

Science.gov (United States)

Ionin, Andrei A.; Kozlov, A. Yu; Seleznev, L. V.; Sinitsyn, D. V.

2009-03-01

A compact capacitive transverse RF-discharge-pumped slab CO laser with cryogenically cooled electrodes, which operates both in the cw and repetitively pulsed regimes, is fabricated. The laser operation is studied in the free running multifrequency regime at the vibrational - rotational transitions of the fundamental (V + 1 → V) vibrational bands of the CO molecule in the spectral region from 5.1 to 5.4 μm. Optimal operation conditions (gas mixture composition and pressure, RF pump parameters) are determined. It is shown that only gas mixtures with a high content of oxygen (up to 20% with respect to the concentration of CO molecules) can be used as an active medium of this laser. It is demonstrated that repetitively pulsed pumping is more efficient compared to cw pumping. In this case, quasi-cw lasing regime can be obtained. The maximum average output power of ~12 W was obtained for this laser operating on fundamental bands and its efficiency achieved ~14 %. The frequency-selective operation regime of the slab RF-discharge-pumped CO laser was realised at ~ 100 laser lines in the spectral region from 5.0 to 6.5 μm with the average output power of up to several tens of milliwatts in each line. Lasing at the transitions of the first vibrational overtone (V + 2 → V) of the CO molecule is obtained in the spectral region from 2.5 to 3.9 μm. The average output power of the overtone laser achieved 0.3 W. All the results were obtained without the forced gas mixture exchange in the discharge chamber. Under fixed experimental conditions, repetitively pulsed lasing (with fluctuations of the output characteristics no more than ±10 %) was stable for more than an hour.

Treatment of striae distensae with needling therapy versus CO2 fractional laser.

Science.gov (United States)

Khater, Mohamed H; Khattab, Fathia M; Abdelhaleem, Manal R

2016-01-01

Striae are atrophic dermal scars with overlying epidermal atrophy causing cosmetic concern. This study assesses and compares the efficacy and safety of needling therapy versus CO2 fractional laser in treatment of striae. Twenty Egyptian female patients with striae in the abdomen and lower limbs were involved in the study. The patients were treated with needling therapy and CO2 laser every 1 month for 3 sessions. Follow-up by digital photography and skin biopsy was conducted at baseline and 6 months after treatment. Clinical improvement was assessed by comparing photographs and patient's satisfaction before and after treatment. Nine of 10 (90%) needle-treated patients showed improvement. Among them, 3 (30%) had good, 4 (40%) had fair, and 2 (20%) had poor improvements; however, 1 (10%) did not show any improvement after the treatment. In CO2-laser treated patients, 5 of 10 (50%) of the patients showed clinical improvement; 1 (10%) were good, 3 (30%) were fair, and 1 (10%) were poor; however, 5 (50%) did not show improvement. The results support the use of microneedle therapy over CO2 lasers for striae treatment.

Retention of radiolytic CO gas in irradiated pepper grains and irradiation detection of spices and dry grains with the level of stocked CO gas

International Nuclear Information System (INIS)

Furuta, M.; Dohmaru, T.; Katayama, T.; Toratani, H.; Takeda, A.

1995-01-01

The release of radiolytic CO gas from 60Co gamma-irradiated pepper seeds was unexpectedly slower than that of radiolytic H2 gas during a storage period after irradiation. These gases were retained in the grains and could be recovered by pulverization under gaslight condition. Using this procedure, 10-kGy-irradiated pepper grains could be distinguished from nonirradiated samples for more than 2 months by the level of CO and H2 gases. The patterns of CO change at 10, 20, and 30 kGy were similar, and the CO amounts were proportional to irradiation doses at any point of the storage period after irradiation. 60Co gamma-irradiated grains of allspice, cinnamon, cumin, polished rice, and wheat could be distinguished from nonirradiated ones by the level of retained CO gas even after 2 months of storage at room temperature. Thus, radiolytic CO gas could be an effective probe for rapid screening of irradiated pepper and dry grains

CO2 Laser Cutting of Hot Stamping Boron Steel Sheets

OpenAIRE

Pasquale Russo Spena

2017-01-01

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 wer...

High pressure X-ray preionized TEMA-CO2 laser

Science.gov (United States)

Bonnie, R. J. M.; Witteman, W. J.

1987-09-01

The construction of a high-pressure (up to 20 atm) transversely excited CO2 laser using transverse X-ray preionization is described. High pressure operation was found to be greatly improved in comparison to UV-preionized systems. Homogeneous discharges have been achieved in the pressure range 5-20 atm, yielding a specific laser output in the order of 35 J/l.

Investigation of small-scale optical inhomogeneities in an electroionization CO/sub 2/-laser

Energy Technology Data Exchange (ETDEWEB)

Borovkov, V V; Kornilov, V G; Lazhintsev, B V; Nor-arevian, V A; Sukhanov, L V

1987-08-01

A technique for the interferometer investigation of optical inhomogeneities in an electroionization CO/sub 2/-laser in the free-oscillation regime is developed which involves active-medium sounding that is coaxial with the laser resonator. Experimental results are presented on small-scale optical inhomogeneities for a pulsed electroionization laser pumped by a nonself-sustained discharge in a CO/sub 2/:N/sub 2/:He = 1:3:6 mixture at a total pressure of 1 atm. 11 references.

Influence of acoustic waves on TEA CO2 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 CO2 lasers. The authors show that acoustic waves generated inside the cavity lead to deterioration in beam quality...

Parameter optimization for selective laser melting of TiAl6V4 alloy by CO2 laser

Science.gov (United States)

Baitimerov, R. M.; Lykov, P. A.; Radionova, L. V.; Safonov, E. V.

2017-10-01

TiAl6V4 alloy is one of the widely used materials in powder bed fusion additive manufacturing technologies. In recent years selective laser melting (SLM) of TiAl6V4 alloy by fiber laser has been well studied, but SLM by CO2-lasers has not. SLM of TiAl6V4 powder by CO2-laser was studied in this paper. Nine 10×10×10 mm cubic specimens were fabricated using different SLM process parameters. All of the fabricated specimens have a good dense structure and a good surface finish quality without dimensional distortion. The lowest porosity that was achieved was about 0.5%.

Sb{sub 2}S{sub 3}:C/CdS p-n junction by laser irradiation

Energy Technology Data Exchange (ETDEWEB)

Arato, A. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon (Mexico); Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia-Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico); Cardenas, E. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon (Mexico); Shaji, S. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon (Mexico); Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia-Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico); O' Brien, J.J.; Liu, J. [Center for Nanoscience, University of Missouri-St. Louis, One University Boulevard, St. Louis, Missouri-63121 (United States); Department of Chemistry and Biochemistry, University of Missouri-St. Louis, One University Boulevard, St. Louis, Missouri-63121 (United States); Castillo, G. Alan; Das Roy, T.K. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon (Mexico); Krishnan, B. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon (Mexico); Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia-Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico)], E-mail: bkrishnan@fime.uanl.mx

2009-02-02

In this paper, we report laser irradiated carbon doping of Sb{sub 2}S{sub 3} thin films and formation of a p-n junction photovoltaic structure using these films. A very thin carbon layer was evaporated on to chemical bath deposited Sb{sub 2}S{sub 3} thin films of approximately 0.5 {mu}m in thickness. Sb{sub 2}S{sub 3} thin films were prepared from a solution containing SbCl{sub 3} and Na{sub 2}S{sub 2}O{sub 3} at 27 deg. C for 5 h and the films obtained were highly resistive. These C/Sb{sub 2}S{sub 3} thin films were irradiated by an expanded laser beam of diameter approximately 0.5 cm (5 W power, 532 nm Verdi laser), for 2 min at ambient atmosphere. Morphology and composition of these films were analyzed. These films showed p-type conductivity due to carbon diffusion (Sb{sub 2} S{sub 3}:C) by the thermal energy generated by the absorption of laser radiation. In addition, these thin films were incorporated in a photovoltaic structure Ag/Sb{sub 2}S{sub 3}:C/CdS/ITO/Glass. For this, CdS thin film of 50 nm in thickness was deposited on a commercially available ITO coated glass substrate from a chemical bath containing CdCl{sub 2}, sodium citrate, NH{sub 4}OH and thiourea at 70 deg. C . On the CdS film, Sb{sub 2}S{sub 3}/C layers were deposited. This multilayer structure was subjected to the laser irradiation, C/Sb{sub 2}S{sub 3} side facing the beam. The p-n junction formed by p-Sb{sub 2}S{sub 3}:C and n-type CdS showed V{sub oc} = 500 mV and J{sub sc} = 0.5 mA/cm{sup 2} under illumination by a tungsten halogen lamp. This work opens up a new method to produce solar cell structures by laser assisted material processing.

Part II. Large scale applications of Ni{sub x}Mn{sub 0.8-x}Mg{sub 0.2}Fe{sub 2}O{sub 4}; 0.1 {<=} x {<=} 0.35 using laser irradiation

Energy Technology Data Exchange (ETDEWEB)

Ahmed, M.A., E-mail: moala1947@yahoo.com [Materials Science. Lab (1), Physics Department, Faculty of Science, Cairo University, Giza (Egypt); Bishay, Samiha T. [Department of Physics, Faculty of Girls for Art, Science and Education, Ain Shams University, Cairo (Egypt); El-dek, S.I.; Omar, G. [Materials Science. Lab (1), Physics Department, Faculty of Science, Cairo University, Giza (Egypt)

2011-07-28

Highlights: >X-ray diffractograms of Ni{sub x}Mn{sub 0.8-x}Mg{sub 0.2}Fe{sub 2}O{sub 4} samples before and after laser irradiation are characteristic of cubic spinel structure with better crystallinity after irradiation. > The crystal size of the ferrite increases after laser irradiation. > The main conduction mechanism in the investigated system is the correlated barrier hopping and it is the same before and laser irradiation. > The conductivity decreases after laser irradiation. - Abstract: Ni{sub x}Mn{sub 0.8-x}Mg{sub 0.2}Fe{sub 2}O{sub 4}; 0.1 {<=} x {<=} 0.35 was prepared by standard ceramic technique at sintering temperature 1200 deg. C using heating / cooling rate 4 deg. C/min. The samples were irradiated by Nd YAG pulsed laser with energy of the pulse 250 mJ. X-ray diffractograms reveal cubic spinel structure for all the samples before and after laser irradiation. After laser irradiation, better crystallinity was obtained in a form of an increase in the calculated crystal size. This increase was discussed as due to the change in the valence of some ions like Fe{sup 3+}, Ni{sup 2+} and Mn{sup 2+}. The conductivity of all the investigated samples decreases after laser irradiation and becomes temperature independent for a wider range than that before irradiation. This was ascribed to electron rearrangement after laser irradiation. Accordingly, these ferrites are recommended to be useful in electronic devices.

Tritium removal by CO2 laser heating

International Nuclear Information System (INIS)

Skinner, C.H.; Kugel, H.; Mueller, D.

1997-01-01

Efficient techniques for rapid tritium removal will be necessary for ITER to meet its physics and engineering goals. One potential technique is transient surface heating by a scanning CO 2 or Nd:Yag laser that would release tritium without the severe engineering difficulties of bulk heating of the vessel. The authors have modeled the heat propagation into a surface layer and find that a multi-kW/cm 2 flux with an exposure time of order 10 ms is suitable to heat a 50 micron co-deposited layer to 1,000--2,000 degrees. Improved wall conditioning may be a significant side benefit. They identify remaining issues that need to be addressed experimentally

Tritium removal by CO2 laser heating

International Nuclear Information System (INIS)

Skinner, C.H.; Kugel, H.; Mueller, D.

1997-10-01

Efficient techniques for rapid tritium removal will be necessary for ITER (International Thermonuclear Experimental Reactor) to meet its physics and engineering goals. One potential technique is transient surface heating by a scanning CO 2 or Nd:YAG laser that would release tritium without the severe engineering difficulties of bulk heating of the vessel. The authors have modeled the heat propagation into a surface layer and find that a multi-kW/cm 2 flux with an exposure time of order 10 msec is suitable to heat a 50 micron co-deposited layer to 1,000--2,000 degrees. Improved wall conditioning may be a significant side benefit. They identify remaining issues that need to be addressed experimentally

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...... connection between the smallest avail-able spot size and cutting speed in mild steel, whereas the conditions in stainless steel, depends strongly on the flow conditions in the cut kerf, and not only on the focal spot size....

CO2 and Nd:YAP laser interaction with lithium disilicate and Zirconia dental ceramics: A preliminary study

Science.gov (United States)

Rocca, Jean-Paul; Fornaini, Carlo; Brulat-Bouchard, Nathalie; Bassel Seif, Samy; Darque-Ceretti, Evelyne

2014-04-01

Lithium disilicate and Zirconia ceramics offer a high level of accuracy when used in prosthetic dentistry. Their bonding using different resins is highly dependent on micro-mechanical interlocking and adhesive chemical bonding. Investigation of the performances of high strength ceramics when their surface is modified for chemical and mechanical bonding is then required. The aim of this study is to investigate the possibility of using laser for surface treatment of different high strength CAD/CAM ceramics and thus to improve their mechanical and chemical properties. Thirty two CAD/CAM ceramic discs were divided into two different groups: lithium disilicate ceramics (IPS e.max CAD®, Ivoclar, Vivadent, Italy) and Zirconia ceramics (IPS e.max ZirCAD®, Ivoclar, Vivadent, Italy). The Laser surface treatment was performed by Carbon Dioxide laser (Dream Pulse Laser®, Daeshin Enterprise Corp., Korea) at 20 W, 25 W and 30 W CW and by Neodymium Yttrium Aluminum Perovskite laser (Nd:YAP Lokki®, Lobel Medical, France) at 10 W and 30 Hz. Physical modifications of the irradiated ceramic discs were observed by scanning electron microscopy (SEM) and chemically analyzed by Energy-Dispersive Spectroscopy (EDS). Surface wettability was tested using the water drop test and the crystalline structure was investigated using X-ray diffraction (XRD). The macroscopic observation showed a shinier structure in all the groups, while at the SEM observation only CO2 25 W and 30 W treated groups showed cracks and fissures. In the conditions of this study, CO2 laser and Nd:YAP laser with the parameters used create chemical and physical surface modifications of the ceramics, indicating the possibility of an improvement in adhesion of the tested ceramics.

Improvement of laser irradiation uniformity in GEKKO XII glass laser system

International Nuclear Information System (INIS)

Miyanaga, Noriaki; Matsuoka, Shinichi; Ando, Akinobu; Amano, Shinji; Nakatsuka, Masahiro; Kanabe, Tadashi; Jitsuno, Takahisa; Nakai, Sadao

1995-01-01

The uniform laser irradiation is one of key issues in the direct drive laser fusion research. The several key technologies for the uniform laser irradiation are reported. This paper includes the uniformity performance as a result of the introduction of the random phase plate, the partially coherent light and the beam smoothing by spectral dispersion into the New Gekko XI glass laser system. Finally the authors summarize the overall irradiation uniformity on the spherical target surface by considering the power imbalance effect. The technologies developed for the beam smoothing and the power balance control enable them to achieve the irradiation nonuniformities of around 1% level for a foot pulse and of a few % for a main drive pulse, respectively

Laser irradiation and thermal treatment inducing selective crystallization in Sb2O3-Sb2S3 glassy films

Science.gov (United States)

Avila, L. F.; Pradel, A.; Ribeiro, S. J. L.; Messaddeq, Y.; Nalin, M.

2015-02-01

The influence of both thermal treatment and laser irradiation on the structural and optical properties of films in the Sb2O3-Sb2S3 system was investigated. The films were prepared by RF-sputtering using glass compositions as raw materials. Irreversible photodarkening effect was observed after exposure the films to a 458 nm solid state laser. It is shown, for the first time, the use of holographic technique to measure "in situ", simultaneously and independently, the phase and amplitude modulations in glassy films. The films were also photo-crystallized and analysed "in situ" using a laser coupled to a micro-Raman equipment. Results showed that Sb2S3 crystalline phase was obtained after irradiation. The effect of thermal annealing on the structure of the films was carried out. Different from the result obtained by irradiation, thermal annealing induces the crystallization of the Sb2O3 phase. Photo and thermal induced effects on films were studied using UV-Vis and Raman spectroscopy, atomic force microscopy (AFM), thermal analysis (DSC), X-ray diffraction, scanning electron microscopy (MEV) and energy-dispersive X-ray spectroscopy (EDX).

Argon laser irradiation of the otolithic organ

Energy Technology Data Exchange (ETDEWEB)

Okuno, T.; Nomura, Y.; Young, Y.H.; Hara, M. (Univ. of Tokyo (Japan))

1990-12-01

An argon laser was used to irradiate the otolithic organs of guinea pigs and cynomolgus monkeys. After stapedectomy, the argon laser (1.5 W x 0.5 sec/shot) irradiated the utricle or saccule without touching the sensory organs. The stapes was replaced over the oval window after irradiation. The animals used for acute observation were killed immediately for morphologic studies; those used for long-term observation were kept alive for 2, 4, or 10 weeks. Acute observation revealed that sensory and supporting cells were elevated from the basement membrane only in the irradiated area. No rupture of the membranous labyrinth was observed. Long-term observation revealed that the otolith of the macula utriculi had disappeared in 2-week specimens. The entire macula utricili had disappeared in 10-week specimens. No morphologic changes were observed in cochlea, semicircular canals, or membranous labyrinth. The saccule showed similar changes.

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%.

Surface modification of RuO2 electrodes by laser irradiation and ion ...

Indian Academy of Sciences (India)

RuO2 thin layers were deposited on Ti supports by thermal decomposition of RuCl3 at 400°C. Some of the samples were subjected to laser irradiation between 0.5 and 1.5 J cm-2. Some others to Kr bombardment with doses between 1015 and 1016 cm-2. Modifications introduced by the surface treatments were monitored ...

Photoacoustic CO2 sensor based on a DFB diode laser at 2.7 μm

Science.gov (United States)

Wolff, M.; Germer, M.; Groninga, H. G.; Harde, H.

2008-01-01

We present a new detection scheme for carbon dioxide (CO{2}) based on a custom-made room temperature distributed feedback (DFB) diode laser at 2.7 μm, currently representing one of the lasers with the highest emission wavelength of its kind. The detector's especially compact and simple set-up is based on photoacoustic spectroscopy (PAS). This method makes use of the transformation of absorbed modulated radiation into a sound wave. The sensor enables a very high detection sensitivity for CO{2} in the ppb range. Furthermore, the carefully selected spectral region as well as the narrow bandwidth and wide tunability of the single-mode laser ensure an excellent selectivity. Even measurements of different CO{2} isotopes can be easily performed. This enables applications in industrial sensing and medical diagnostics (e.g. 13C-breath tests).

Welding of dissimilar metals by CO2 lasers

International Nuclear Information System (INIS)

Garciandia, F.; Zubiri, F.; Etayo, J.L.; Cervantes, R.; Iriberri, I.

1998-01-01

The work carried out in CETENASA (laser department) in order to weld dissimilar metals is summarized. The involved metallic pair is M-35 and F-143, a high speed steel and a spring steel, respectively. Looking at the chemical composition of the involved alloys that will appear later, it can be easily understood the difficulty to obtain welded parts with structures metallurgically acceptable because of the high cracking degree that these materials show, specially M-35. The principles of a study which is being developed in the authors laboratory and which shows some interesting CO 2 laser possibilities are presented. (Author) 2 refs

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.

Direct diode lasers with comparable beam quality to fiber, CO2, and solid state lasers

Science.gov (United States)

Huang, Robin K.; Chann, Bien; Burgess, James; Kaiman, Michael; Overman, Robert; Glenn, John D.; Tayebati, Parviz

2012-03-01

TeraDiode has produced kW-class ultra-high brightness fiber-coupled direct diode lasers. A fiber-coupled direct diode laser with a power level of 2,040 W from a 50 μm core diameter, 0.15 numerical aperture (NA) output fiber at a single center wavelength was demonstrated. This was achieved with a novel beam combining and shaping technique using COTS diode lasers. The fiber-coupled output corresponds to a Beam Parameter Product (BPP) of 3.75 mm-mrad and is the lowest BPP kW-class direct diode laser yet reported. This laser is suitable for industrial materials processing applications, including sheet metal cutting and welding. This 2-kW fiber-coupled direct diode laser has comparable brightness to that of industrial fiber lasers and CO2 lasers, and is over 10x brighter than state-of-the-art direct diode lasers.

Effects of laser acupoint irradiation on blood glucose and glycosylated hemoglobin in type 2 diabetes mellitus

Science.gov (United States)

Hui-Hui, Liu; Guo-Xin, Xiong; Li-Ping, Zhang

2016-06-01

To investigate the effects of semiconductor laser acupoint irradiation on blood glucose, glycosylated hemoglobin and physical fitness in type 2 diabetes mellitus, 44 cases of type 2 diabetic patients were randomly divided into a control group and a treatment group. All patients in both groups were given a drug treatment. The Hegu, Quchi and Zusanli acupoints of patients in the treatment group were then irradiated daily for 15 d with a 10 MW semiconductor laser. Before and after treatment, patients in both groups underwent a variety of tests and measurements: a two-hour postprandial blood glucose test; a glycosylated hemoglobin test and body mass index (BMI), waist-to-hip ratio (WHR) and body fat percentage (BFP) measurements. The data detected after treatment greatly decreased in the treatment group and was significantly different from that in the control group. It is shown that the acupoint irradiation with a semiconductor laser can improve two-hour postprandial blood glucose, glycosylated hemoglobin and some physical fitness measurements in type 2 diabetes mellitus patients.

Influence of laser-target interaction on the polarization of a CO2-laser

International Nuclear Information System (INIS)

Du, K.; Herziger, G.; Loosen, P.; Seelig, W.

1988-01-01

Laser materials processing shows a special peculiarity compared to other customary techniques: the generally reflecting target introduces optical feedback into the system. This feedback changes the mode properties of the laser radiation according to the targets dynamics. The authors report on one of these aspects of laser-target interaction resulting in the change of the polarization of the incident light. Based of rate equations, a theoretical model is presented in this paper that allows the calculation of this change with respect of the target properties, yielding a simple relation for the two orthogonal planes of polarization of a laser mode. This relation turns out to be linearly dependent of a function ψ (t) which describes the optical feedback. The relation holds for target reflexions of up to 10% and four times larger than τ 2 x τ 2 /τ 1 - τ 2 (where τ 1 , τ 2 are the time constants of the passive resonator for the two orthogonal planes of polarization). The model offers a method for the modulation for the modulation of laser radiation without change of frequency or intensity. It might also be of interest for high-power CO 2 laser cutting and welding of metals

Application of CO II laser for removal of oral mucocele

Science.gov (United States)

Kato, J.; Moriya, K.; Hirai, Y.

2006-02-01

Mucocele is an oral soft tissue cyst caused by the disturbance of saliva flow. Mucocele is widely observed in child patients and recurrence is high. The objective of this study was to clarify the effect of CO II laser irradiation in the case of mucocele. A CO II laser was used on 45 subjects, aged between 0 to 15 years, having mucocele on lip, lingual, or buccal mucosa. Our procedure in using CO II laser was not to vaporize the mucocele but to remove the whole mucocele mass. The border of mucocele was firstly incised by laser following defocusly ablating the root or body of mucocele separating from sorrounding tissue. As a result, mucocele was easily and completely removed without breaking the wall of mucocele. None of the cases required suturing. The results were as follows. 1. The mucocele of lip or lingual mucosa with a rich blood supply, was efficiently removed, without bleeding, giving a clear operative field during the operation. 2. The surgery itself was simple and less time-consuming. 3. After two or three weeks the wound was completely healed without almost any discomfort in all patients 4. Wound contraction and scarring were decreased or eliminated. 5. The reoccurrence of mucocele was not seen, except only in one case of lingual mucocele. In conclusion the use of CO II laser proved to be a very safe and effective mode for the removal of mucocele, especially in small children.

In situ study of the effects of heavy-ion irradiation on co-evaporated CoSi2 films

International Nuclear Information System (INIS)

Allen, C.W.; Smith, D.A.

1990-11-01

The in situ ion irradiation capability of Argonne's HVEM-Tandem User Facility has been employed to determine the effects of 1.5 MeV Kr + irradiation and 300 kV electron irradiation on the crystallization of as-deposited and of partially crystallized 40 nm thick films of CoSi 2 . Ion fluxes ranged from 8.5 x 10 14 to 6.8 x 10 15 m -2 s -1 for which beam heating effects may be neglected. The maximum electron flux at 300 kV was 0.8 x 10 23 m -2 s -1 . The maximum temperature at which crystalline CoSi 2 is amorphized by the ion irradiation of flux = 6.8 x 10 15 m -2 s -1 is between 250 and 280 K. At higher temperatures amorphous material crystallizes by growth of any preexisting crystals and by classical nucleation and growth, with radial growth rates which are proportional to ion flux. The average degree of transformation per ion is 4 x 10 -26 m 3 per ion. Thermally induced crystallization of as-deposited films occurs above approximately 420 K. For ion doses at least as low as 3.4 x 10 16 m -2 ion irradiation at 300 K promotes thermal crystallization at 450 K, by virtue of enhanced apparant nucleation and at large doses, by enhanced growth rate. 8 refs., 2 figs

Prediction of rate of CO2 assimilation of leaf lettuce under low light irradiation during storage

International Nuclear Information System (INIS)

Uchino, T.; Harada, F.; Hu, W.

2003-01-01

The rate of CO 2 assimilation of leaf lettuce changed with its respiration rate and gas constitution in a storage chamber. The optimum irradiance on the surface of leaf lettuce during storage using low light irradiation can be obtained by the prediction of the rate of CO 2 assimilation. For the above mentioned purpose the following equation were derived. -kd[C]/dt=0.5(1-f)I([C]-Γ/4.5[C]+10.5Γ)-ae -bt where, k: proportional constant (4.87×10 -3 mol⋅m -2 ) [C]: CO 2 concentration (ppm), t: time (h), f: fraction of light not absorbed by chloroplasts (0.23), I: irradiance (μmol⋅m-2⋅s -1 ), Γ: CO 2 compensation point without respiration (21.5ppm), a, b: parameters (0.308μmol⋅m -2 ⋅s -1 , 0.010h -1 ). Calculated values of rate of CO 2 assimilation by the equation agreed well with experimental ones at 3.4 and 6.5μmol⋅m -2 ⋅s -1 of irradiance, so it appeared that the assimilation rate could be sufficiently predicted

An investigation of CO2 laser scleral buckling using moiré interferometry.

Science.gov (United States)

Maswadi, Saher M; Dyer, Peter E; Verma, Dinesh; Jalabi, Wadah; Dave, Dinesh

2002-01-01

To demonstrate suitability of moiré interferometry to assess and quantify laser-induced shrinkage of scleral collagen for buckling procedures. Scleral buckling of human cadaver eyes was investigated using a Coherent Ultrapulse CO2 laser. Projection moiré interferometry was employed to determine the out-of plane displacement produced by laser exposure, and in-situ optical microscopy of reference markers on the eye was used to measure in-plane shrinkage. Measurements based on moiré interferometry allow a three dimensional view of shape changes in the eye surface as laser treatment proceeds. Out-of-plane displacement reaches up to 1.5 mm with a single laser spot exposure. In-plane shrinkage reached a maximum of around 30%, which is similar to that reported by Sasoh et al (Ophthalmic Surg Lasers. 1998;29:410) for a Tm:YAG laser. The moiré technique is found to be suitable for quantifying the effects of CO2 laser scleral shrinkage and buckling. This can be further developed to provide a standardized method for experimental investigations of other laser sources for scleral shrinkage.

Role of laser fluence in protein synthesis of cultured DRG neurons following low-level laser irradiation

Science.gov (United States)

Zheng, Liqin; Qiu, Caimin; Wang, Yuhua; Zeng, Yixiu; Yang, Hongqin; Zhang, Yanding; Xie, Shusen

2014-11-01

Low-level lasers have been used to relieve pain in clinical for many years. But the mechanism is not fully clear. In animal models, nitric oxide (NO) has been reported involving in the transmission and modulation of nociceptive signals. So the objective of this study was to establish whether low-level laser with different fluence could stimulate the production of nitric oxide synthese (NOS), which produces NO in cultured primary dorsal root ganglion neurons (DRG neurons). The primary DRG neurons were isolated from healthy Sprague Dawley rats (8-12 weeks of age) and spread on 35 mm culture dishes specially used for confocal microscopy. 24 hours after spreading, cells were irradiated with 658 nm laser for two consecutive days at the energy density of 20, 40, 60 and 80 mJ·cm-2 respectively. Control groups were not exposed to the laser, but were kept under the same conditions as the irradiated ones. The synthesis of NOS after laser irradiation was detected by immunofluorescence assay, and the changes of NOS were evaluated using confocal microscopy and Image J software. The results showed that all the laser fluence could promote the production of NOS in DRG neurons, especially the 60 mJ·cm-2 . These results demonstrated that low-level laser irradiation could modify protein synthesis in a dose- or fluence- dependent manner, and indicated that low-level laser irradiation might achieve the analgesic effect through modulation of NO production.

Numerical simulation of the shape of laser cut for fiber and CO2 lasers

Science.gov (United States)

Zaitsev, A. V.; Ermolaev, G. V.; Polyanskiy, T. A.; Gurin, A. M.

2017-10-01

The results of numerical modeling of steel plate laser cutting with nitrogen as assist gas with consideration of heat transfer into a bulk material are presented. In this work we studied a distribution of absorbed radiation energy inside cut kerf and the difference between CO2 and fiber laser radiation propagation and absorption. The influence of secondary absorption of reflected from the cut front radiation on stability of melt hydrodynamics is discussed for different laser types.

Pulsed-laser ablation of co-deposits on JT-60 graphite tile

International Nuclear Information System (INIS)

Sakawa, Youichi; Watanabe, Daisuke; Shibahara, Takahiro; Sugiyama, Kazuyoshi; Tanabe, Tetsuo

2007-01-01

Pulsed laser ablation of the co-deposits on a JT-60 open-divertor tile using the fourth harmonic of a 20 ps-Nd: YAG laser has been investigated. With increasing the laser intensity, three regions, non-ablation region (NAR), weak-ablation region (WAR), and strong-ablation region (SAR) were distinguished. Transition from NAR to WAR and WAR to SAR occurred at the threshold laser intensity for laser ablation and that for strong ionization of carbon atoms, respectively. The ablation accompanied desorption of H 2 and C 2 H 2 , with minor contribution of other hydrocarbons, while production of H 2 O was small. In NAR and WAR the number of the hydrogen desorbed by the laser irradiation was less than that of hydrogen retained in the ablated volume, while in SAR it was much larger, owing to thermal desorption of hydrogen gas from the region surrounding the ablated volume. For the ablative removal of hydrogen isotopes, SAR is more desirable because of higher removal efficiency and less production of hydrocarbons

Pulsed-laser ablation of co-deposits on JT-60 graphite tile

Energy Technology Data Exchange (ETDEWEB)

Sakawa, Youichi [Institute of Laser Engineering, Osaka University, Yamadaoka, Suita, Osaka 565-0871 (Japan)]. E-mail: sakawa-y@ile.osaka-u.ac.jp; Watanabe, Daisuke [Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya, Aichi 464-8603 (Japan); Shibahara, Takahiro [Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya, Aichi 464-8603 (Japan); Sugiyama, Kazuyoshi [Interdisciplinary School of Engineering Science, Kyushu University, Fukuoka, Fukuoka 812-8581 (Japan); Tanabe, Tetsuo [Interdisciplinary School of Engineering Science, Kyushu University, Fukuoka, Fukuoka 812-8581 (Japan)

2007-08-01

Pulsed laser ablation of the co-deposits on a JT-60 open-divertor tile using the fourth harmonic of a 20 ps-Nd: YAG laser has been investigated. With increasing the laser intensity, three regions, non-ablation region (NAR), weak-ablation region (WAR), and strong-ablation region (SAR) were distinguished. Transition from NAR to WAR and WAR to SAR occurred at the threshold laser intensity for laser ablation and that for strong ionization of carbon atoms, respectively. The ablation accompanied desorption of H{sub 2} and C{sub 2}H{sub 2}, with minor contribution of other hydrocarbons, while production of H{sub 2}O was small. In NAR and WAR the number of the hydrogen desorbed by the laser irradiation was less than that of hydrogen retained in the ablated volume, while in SAR it was much larger, owing to thermal desorption of hydrogen gas from the region surrounding the ablated volume. For the ablative removal of hydrogen isotopes, SAR is more desirable because of higher removal efficiency and less production of hydrocarbons.

Frequency stabilization of quantum cascade laser for spectroscopic CO2 isotope analysis

Science.gov (United States)

Han, Luo; Xia, Hua; Pang, Tao; Zhang, Zhirong; Wu, Bian; Liu, Shuo; Sun, Pengshuai; Cui, Xiaojuan; Wang, Yu; Sigrist, Markus W.; Dong, Fengzhong

2018-06-01

Using off-axis integrated cavity output spectroscopy, named OA-ICOS, the absorption spectrum of CO2 at 4.32 μm is recorded by using a quantum cascade laser (QCL). The concentration of the three isotopologues 16O12C16O, 16O13C16O and 16O12C18O is detected simultaneously. The isotope abundance ratio of 13C and 18O in CO2 gas can be obtained, which is most useful for ecological research. Since the ambient temperature has a serious influence on the output wavelength of the laser, even small temperature variations seriously affect the stability and sensitivity of the system. In this paper, a wavelength locking technique for QCL is proposed. The output of a digital potentiometer integrated in the laser current driver control is modified by software, resulting in a correction of the driving current of the laser and thus of its wavelength. This method strongly reduces the influence of external factors on the wavelength drift of lasers and thus substantially improves the stability and performance of OA-ICOS as is demonstrated with long-time measurements on CO2 in laboratory air.

Efficient extreme ultraviolet plasma source generated by a CO2 laser and a liquid xenon microjet target

Science.gov (United States)

Ueno, Yoshifumi; Ariga, Tatsuya; Soumagne, George; Higashiguchi, Takeshi; Kubodera, Shoichi; Pogorelsky, Igor; Pavlishin, Igor; Stolyarov, Daniil; Babzien, Marcus; Kusche, Karl; Yakimenko, Vitaly

2007-05-01

We demonstrated efficacy of a CO2-laser-produced xenon plasma in the extreme ultraviolet (EUV) spectral region at 13.5nm at variable laser pulse widths between 200ps and 25ns. The plasma target was a 30μm liquid xenon microjet. To ensure the optimum coupling of CO2 laser energy with the plasma, they applied a prepulse yttrium aluminum garnet laser. The authors measured the conversion efficiency (CE) of the 13.5nm EUV emission for different pulse widths of the CO2 laser. A maximum CE of 0.6% was obtained for a CO2 laser pulse width of 25ns at an intensity of 5×1010W/cm2.

Efficient extreme ultraviolet plasma source generated by a CO2 laser and a liquid xenon microjet target

International Nuclear Information System (INIS)

Ueno, Yoshifumi; Ariga, Tatsuya; Soumagne, George; Higashiguchi, Takeshi; Kubodera, Shoichi; Pogorelsky, Igor; Pavlishin, Igor; Stolyarov, Daniil; Babzien, Marcus; Kusche, Karl; Yakimenko, Vitaly

2007-01-01

We demonstrated efficacy of a CO 2 -laser-produced xenon plasma in the extreme ultraviolet (EUV) spectral region at 13.5 nm at variable laser pulse widths between 200 ps and 25 ns. The plasma target was a 30 μm liquid xenon microjet. To ensure the optimum coupling of CO 2 laser energy with the plasma, they applied a prepulse yttrium aluminum garnet laser. The authors measured the conversion efficiency (CE) of the 13.5 nm EUV emission for different pulse widths of the CO 2 laser. A maximum CE of 0.6% was obtained for a CO 2 laser pulse width of 25 ns at an intensity of 5x10 10 W/cm 2

Experimental and theoretical electron-beam-sustained CO2 laser output at approx. 200 and approx. 3000K

International Nuclear Information System (INIS)

Douglas-Hamilton, D.H.; Feinberg, R.M.; Lowder, R.S.

1975-01-01

A six-temperature kinetic model of the He : He 2 Co 2 : N 2 : CO laser system is developed, in which five temperatures describe the vibrational excitation of the three CO 2 modes, N 2 , and CO, while the sixth refers to the kinetic temperature. Theoretical predictions of gain and laser output are compared with experiments performed on an electron-beam sustained laser used at atmospheric pressure. Gain and laser measurements have been made with initial gas temperature near 200 and 300 degreeK. A stable discharge can be produced in this type of laser in gas mixtures containing no He, and successful electric laser operation has been demonstrated using H 2 as CO 2 ν 2 deactivant. Various gas mixtures have been investigated experimentally and theoretically; specific output J>100 J/liter atm was obtained both in He : N 2 : CO 2 : H 2 3 : 2 : 1 : 0 and 0 : 3 : 1 : 0.08, with efficiencies near 30%. While the gain measured appears to peak later and decay later than predicted, in all laser output measurements there is good agreement between theoretical prediction and experiment

Miniaturized Laser Heterodyne Radiometer for Measurements of CO2 in the Atmospheric Column

Science.gov (United States)

Wilson, E. L.; Mclinden, M. L.; Miller, J. H.; Allan, G. R.; Lott, L. E.; Melroy, H. R.; Clarke, G. B.

2013-01-01

We have developed a low-cost, miniaturized laser heterodyne radiometer for highly sensitive measurements of carbon dioxide (CO2) in the atmospheric column. In this passive design, sunlight that has undergone absorption by CO2 in the atmosphere is collected and mixed with continuous wave laser light that is step-scanned across the absorption feature centered at 1,573.6 nm. The resulting radio frequency beat signal is collected as a function of laser wavelength, from which the total column mole fraction can be de-convolved. We are expanding this technique to include methane (CH4) and carbon monoxide (CO), and with minor modifications, this technique can be expanded to include species such as water vapor (H2O) and nitrous oxide (N2O).

Thermal imaging of high power diode lasers subject to back-irradiance

Science.gov (United States)

Li, C.; Pipe, K. P.; Cao, C.; Thiagarajan, P.; Deri, R. J.; Leisher, P. O.

2018-03-01

CCD-based thermoreflectance imaging and finite element modeling are used to study the two-dimensional (2D) temperature profile of a junction-down broad-area diode laser facet subject to back-irradiance. By determining the temperature rise in the active region (ΔΤAR) at different diode laser optical powers, back-irradiance reflectance levels, and back-irradiance spot locations, we find that ΔΤAR increases by nearly a factor of three when the back-irradiance spot is centered in the absorbing substrate approximately 5 μm away from the active region, a distance roughly equal to half of the back-irradiance spot FWHM (9 μm). This corroborates prior work studying the relationship between the back-irradiance spot location and catastrophic optical damage, suggesting a strong thermal basis for reduced laser lifetime in the presence of back-irradiance for diode lasers fabricated on absorbing substrates.

Development of control and data processing system for CO2 laser interferometer

International Nuclear Information System (INIS)

Chiba, Shinichi; Kawano, Yasunori; Tsuchiya, Katsuhiko; Inoue, Akira

2001-11-01

CO 2 laser interferometer diagnostic has been operating to measure the central electron density in JT-60U plasmas. We have developed a control and data processing system for the CO 2 laser interferometer with flexible functions of data acquisition, data processing and data transfer in accordance with the sequence of JT-60U discharges. This system is mainly composed of two UNIX workstations and CAMAC clusters, in which the high reliability was obtained by sharing the data process functions to the each workstations. Consequently, the control and data processing system becomes to be able to provide electron density data immediately after a JT-60U discharge, routinely. The realtime feedback control of electron density in JT-60U also becomes to be available by using a reference density signal from the CO 2 laser interferometer. (author)

Diffusion-cooled high-power single-mode waveguide CO2 laser for transmyocardial revascularization

Science.gov (United States)

Berishvili, I. I.; Bockeria, L. A.; Egorov, E. N.; Golubev, Vladimir S.; Galushkin, Michail G.; Kheliminsky, A. A.; Panchenko, Vladislav Y.; Roshin, A. P.; Sigaev, I. Y.; Vachromeeva, M. N.; Vasiltsov, Victor V.; Yoshina, V. I.; Zabelin, Alexandre M.; Zelenov, Evgenii V.

1999-01-01

The paper presents the results on investigations and development of multichannel waveguide CO2 laser with diffusion cooling of active medium excited by discharge of audio-frequency alternating current. The description of high-power single-mode CO2 laser with average beam power up to 1 kW is presented. The result of measurement of the laser basic parameters are offered, as well as the outcomes of performances of the laser head with long active zone, operating in waveguide mode. As an example of application of these laser, various capabilities a description of the developed medical system 'Genom' used in the transmyocardial laser revascularization (TMLR) procedure and clinical results of the possibilities of the TMLR in the surgical treatment are presented.

High-speed scanning ablation of dental hard tissues with a λ = 9.3 μm CO2 laser: adhesion, mechanical strength, heat accumulation, and peripheral thermal damage

Science.gov (United States)

Nguyen, Daniel; Chang, Kwang; Hedayatollahnajafi, Saba; Staninec, Michal; Chan, Kenneth; Lee, Robert; Fried, Daniel

2011-07-01

CO2 lasers can be operated at high laser pulse repetition rates for the rapid and precise removal of dental decay. Excessive heat accumulation and peripheral thermal damage is a concern when using high pulse repetition rates. Peripheral thermal damage can adversely impact the mechanical strength of the irradiated tissue, particularly for dentin, and reduce the adhesion characteristics of the modified surfaces. The interpulpal temperature rise was recorded using microthermocouples situated at the roof of the pulp chamber on teeth that were occlusally ablated using a rapidly-scanned CO2 laser operating at 9.3 μm with a pulse duration of 10 to 15 μs and repetition rate of 300 Hz over a 2 min time course. The adhesion strength of laser treated enamel and dentin surfaces was measured for various laser scanning parameters with and without post-ablation acid etching using the single-plane shear test. The mechanical strength of laser-ablated dentin surfaces were determined via the four-point bend test and compared to control samples prepared with 320 grit wet sand paper to simulate conventional preparations. Thermocouple measurements indicated that the temperature remained below ambient temperature if water-cooling was used. There was no discoloration of either dentin or enamel laser treated surfaces, the surfaces were uniformly ablated, and there were no cracks visible. Four-point bend tests yielded mean mechanical strengths of 18.2 N (s.d. = 4.6) for ablated dentin and 18.1 N (s.d. = 2.7) for control (p > 0.05). Shear tests yielded mean bond strengths approaching 30 MPa for both enamel and dentin under certain irradiation conditions. These values were slightly lower than nonirradiated acid-etched control samples. Additional studies are needed to determine if the slightly lower bond strength than the acid-etched control samples is clinically significant. These measurements demonstrate that enamel and dentin surfaces can be rapidly ablated by CO2 lasers with minimal

Effect of laser irradiation on the structural, morphological and electrical properties of polycrystalline TiO2 thin films

Science.gov (United States)

Khan, M. I.; Ali, Asghar

TiO2 thin film is deposited on glass substrate by sol-gel dip coating technique. After deposition, films were irradiated by continuous wave (CW) diode laser at an angle of 45°. XRD shows both the anatase and brookite phases of TiO2. Nano particles of regular and control sizes are appeared in SEM micrographs. Therefore, shape and size of nano particles can be control by using Laser irradiation. The average sheet resistivity of TiO2 thin film irradiated by 0, 2, 4 and 6 min are 6.72 × 105, 5.32 × 105, 3.44 × 105 and 4.95 × 105 (ohm-m) respectively, according to four point probe.

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

Indian Academy of Sciences (India)

High power industrial multibeam CO2 lasers consist of a large number of closely packed ... by producing pre-ionization using an auxiliary high frequency pulsed ... of few kilowatts output power, multibeam technique is used [2]. .... gas mixture of CO2, N2 and He enters in each discharge tube individually from .... Commercial.

DF--CO2 transfer laser development

International Nuclear Information System (INIS)

Tregay, G.W.; Drexhage, M.G.; Wood, L.M.; Andrysiak, S.J.

1975-01-01

Power extraction and chemiluminescence experiments have been conducted in the large-scale DF-CO 2 transfer chemical laser (TCL) (IRIS-I and IRIS-II) facility at Bell Aerospace Company (BAC). The modular design of the device allowed testing to be conducted with both a supersonic nozzle bank and also in subsonic flow with sonic injection for the deuterium. Power levels of 15 kW at 10.6 μ were obtained in IRIS-I (subsonic) employing an unstable resonator with a 50 percent output coupling ratio and cavity pressure of 35 torr. For IRIS-II (supersonic) somewhat lower power was obtained. In both systems the fluorine dissociation (α = F/F + 2F 2 ) was less than 0.01. Chemiluminescent emission from HF and DF was monitored under zero-power conditions along an axis parallel to the laser-mirror axis. From the measured DF-concentration profiles it can be inferred that vibrationally excited DF is being produced throughout the cavity and, accordingly, the production of DF must be attributed largely to the chain reaction

Diode Laser Irradiation in Endodontic Therapy through Cycles - in vitro Study

Directory of Open Access Journals (Sweden)

Trišić Dijana

2017-07-01

Full Text Available Background/Aim: The aim of this in vitro study was to investigate the influence of irradiation cycles and resting periods, on thermal effects on the external root surface during root canal irradiation of two diode laser systems (940 nm and 975 nm, at output powers of 1 W and 2 W in continuous mode. In previous studies the rising of temperature above 7°C has been reported as biologically accepted to avoid periodontal damage on the external root surface. Material and Methods: Twenty human inferior incisors were randomly distributed into four groups, the 940 nm, and the 975 nm diode laser irradiation, both with an output power of 1 W and 2 W, in continuous mode. The thermographic camera was used to detect temperature variations on the external root surface. Digital radiography of the samples was made. Results: After three cycles of irradiation, at apical third of the root, mean temperature variation by 940 nm diode laser irradiation was 2.88°C for output power of 1 W, and 6.52°C for output power of 2 W. The 975 nm laser caused a higher temperature increase in the apical region, with temperature variation of 13.56°C by an output power of 1 W, and 30.60°C at 2 W, with a statistical significance of p ≤ 0.0001 between two laser systems compared for the same power. The resting periods of 20 s between cycles were enough to lower temperature under 7°C in the case of 1 W and 2 W for 940 nm diode laser, while for 975 nm laser, after three irradiation cycles overheating occurred at both output power rates. Conclusion: Three cycles irradiation of 940 nm diode laser, with resting periods of 20 seconds, allowed safe usage of 1 W and 2 W in CW for endodontic treatment. For 975 nm at a power rate of 1 W, the last resting period drop the temperature near the safe limit and it came under 7°C in a period less than a minute, while at the power of 2 W the resting periods were not long enough for the safe temperature decrease.

Microsecond enamel ablation with 10.6μm CO2 laser radiation

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