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Kibria, G., B. Doloi e B. Bhattacharyya. "Parametric Study and Optimization of Nd: YAG Laser Micro-Turning Process of Different Grade of Alumina Ceramics Based on Taguchi Methodology". International Journal of Surface Engineering and Interdisciplinary Materials Science 2, n. 1 (gennaio 2014): 15–46. http://dx.doi.org/10.4018/ijseims.2014010102.
Testo completoAbstract (sommario):
The present paper addresses an investigation on the effect of process parameters during Nd:YAG laser micro-turning operation of different grade of alumina (Al2O3) ceramic materials. Considering different levels of various process parameters i.e. laser beam average power, pulse frequency, workpiece rotational speed and Y feed rate, Taguchi method based experimental design has been used to construct the set of experiments. The same set of experiments has been utilized to machine 10 mm diameter cylindrical workpiece made of different grades of Alumina ceramics i.e. K60 and K80. Surface roughness (Ra) and micro-turning depth deviation were considered as the process characteristics. Analysis of variance (ANOVA) test was performed for each grade of alumina ceramic to find out the significant process parameters during laser micro-turning process. The optimum process parameters settings for individual responses were obtained by analyzing the signal-to-noise (S/N) ratio. Mathematical models, which correlate the response and process variables, have been developed for all the grades of ceramics. Multi-objective optimization i.e. simultaneous minimization of surface roughness (Ra) and micro-turning depth deviation has been done through combined approach of Taguchi methodology and Grey Relational Analysis.
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Journal, Baghdad Science. "Study The effect of central ion to the dithene complexes on spectral shifting of saturable absorber band". Baghdad Science Journal 8, n. 2 (12 giugno 2011): 465–72. http://dx.doi.org/10.21123/bsj.8.2.465-472.
Testo completoAbstract (sommario):
In this work dithine complexes prepared from dithiol benzil ligand and central ion to the Ni,Pd,Pt, element the ligand and complexes have been investigated using FTIR spectrophotometer and uv-vis-NIR spectral reigns show higher intensity represents the ?-?* transition in the chromopher cycle .These absorption which appear in visible and near IR spectral regions ,According to the complexes of one group ,the spectral shifting due to the change of central ion has been found to be related to atomic number of central ion .This shifting is increased while decreasing the central ion atom number These complexes have been implemented in Nd+2:YAG cavity because each posses resonant absorption band near Nd+2:YAG, Nd+2:Glass emitting at (1060nm). pulse duration measured to complexes dissolved in dioxin(2*10-3M) is very short compared with free running pulse duration ,therefore the complexes work as Q-switch to the NIR lasers.
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Gueorgieva, Tzvetelina G., e Raina T. Gergova. "INVESTIGATION OF ANTIBACTERIAL ACTIVITY OF ND: YAG - LASER AND STANDARD ENDODONTIC TREATMENT". Journal of IMAB - Annual Proceeding (Scientific Papers) 27, n. 2 (24 maggio 2021): 3736–40. http://dx.doi.org/10.5272/jimab.2021272.3736.
Testo completoAbstract (sommario):
Introduction: The microbial infection is one of the main causes of the dental pulp and periodontal diseases. Previously used methods for its elimination are not fully effective, and often some microorganisms in root canals (RC) remain unaffected after treatment. Another modern method for disinfection of root canal system is laser disinfection. Different types of lasers are used - Nd: YAG, Er: YAG, Diode laser. Purpose: The purpose of our study is to compare the antibacterial activity of ND: YAG laser and conventional endodontic therapy in the treatment of infected root canals. Materials and methods The study involved 36 teeth of patients diagnosed with pulp gangrene or chronic periapical periodontitis, requiring endodontic treatment. They were divided into two groups of 18 teeth each one. The teeth in both groups are prepared by Protaper Universal rotary instruments (Maillefer Instruments SA, Ballaigues, Switzerland). In group 1the root canals disinfection is performed with a Nd: YAG laser (source of Nd: YAG laser (1064 nm) is the AT Fidelis - Fotona d.d., Ljubljana laser system). In group 2 was used the following protocol of root canal disinfection: 2.5% sodium hypochlorite solution and 17% EDTA divided by irrigation with distilled water. Then a sterile paper point is placed in the root canals, and a microbiological sample is taken again. Results: In all compared pairs, there was no significantly different effect regarding the number of microorganisms. Conclusions: The disinfection rinsing method with NaOCl has the strongest antimicrobial effect in clinical studies (90% against all microbial isolates). The use of Nd: YAG laser independently is not always sufficient for root canal disinfection - the effect is about 66%.
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Dagenais, D. M., K. P. Koo e A. Dandridge. "Demonstration of low-frequency intensity noise reduction for fiber sensors powered by diode-pumped Nd-YAG lasers". IEEE Photonics Technology Letters 4, n. 5 (maggio 1992): 519–20. http://dx.doi.org/10.1109/68.136507.
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Mohammed, Muneer Khan, Abdulrahman Al-Ahmari e Usama Umer. "Assessment of Direct Laser Writing using Nd YAG Lasers for Microfluidic Applications". International Journal of Manufacturing, Materials, and Mechanical Engineering 5, n. 2 (aprile 2015): 44–58. http://dx.doi.org/10.4018/ijmmme.2015040103.
Testo completoAbstract (sommario):
The rapid growth in the use of Micro/Nano products in variety of industries such as Micro electromechanical systems (MEMS), microelectronics, Biomedical/Bio-MEMS, automotive (motion sensors), telecommunications etc, has demanded new micro manufacturing methods. The challenge with the manufacturing of Microfluidic devices/biochips is that they often make use of broad range of materials within a single chip, making it difficult to manufacture these devices with conventional photolithographic based techniques. Laser processing of materials has proved to be an important tool for the development of these devices because of the accuracy, flexibility and the most important one material independence it offers. This research focus on optimization of laser process parameters for the machining of Microfluidic channels with AISI 1045 steel. Design of experiments (DOE) technique was used in order to study the effect of laser process parameters on rectangular and semicircular cross-section channels.
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Lippert, Burkard M., e Jochen A. Werner. "Comparison of Carbon Dioxide and Neodymium: Yttrium-Aluminum-Garnet Lasers in Surgery of the Inferior Turbinate". Annals of Otology, Rhinology & Laryngology 106, n. 12 (dicembre 1997): 1036–42. http://dx.doi.org/10.1177/000348949710601207.
Testo completoAbstract (sommario):
At the Department of Otorhinolaryngology—Head and Neck Surgery of the University of Kiel, 533 patients with hyperplastic inferior turbinates were treated between 1987 and 1994 with various carbon dioxide (CO2) and neodymium:yttrium-aluminum-garnet (Nd:YAG) laser techniques. We report on the therapeutic results of both types of laser turbinectomy and compare their long-term results with those of submucosal diathermy. Among the different techniques, we preferred the following approaches. The CO2 laser technique involved the application of a few laser spots (laser energy density 6,100 J/cm2 per lesion) to the head of the turbinate under the operating microscope. In the Nd: YAG laser procedure, diffuse, low-power irradiation (laser energy density < 53 kJ/cm2) of the entire concha was performed under endoscopic control. The CO2 laser procedure involved little bleeding and hardly any pain. It produced a positive effect after only a few days and required no follow-up treatment. The success of Nd: YAG laser treatment, by contrast, only became evident after weeks or months, due to the slow scarring process. Compared to submucosal diathermy, both laser methods produced better long-term results. Two years postoperatively, the overall success rate, as defined by patient satisfaction, was 79.6% for the CO2 laser, 68.3% for the Nd: YAG laser, and 36% for submucosal diathermy.
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A.alkarem A.albaqi1, Marwan, Awatef Saber Jasem1 e Adnan Fathel A.azawai2. "The Influence of molecular Effects on Laser Nd:YAG and Diode on Trichophyton Rubrum fungi using RAPD marker". Tikrit Journal of Pure Science 24, n. 6 (3 novembre 2019): 117. http://dx.doi.org/10.25130/j.v24i6.896.
Testo completoAbstract (sommario):
This study was carried out to assess the morphological and molecular effects of the Nd: yag and Diode (semiconductor) lasers on Trichophyton rubrum Fungi using RAPD marke . Sixty samples of skin patches, nail clippings and parts of hair were collected from infected patients of both sexes (34 males and 26 females) for the age group (1-60) year of patients who have attended to Tikrit Teaching Hospital. The T.rubrum fungi was the most common among the skin fungi, T.rubrum radiated by using two lasers: the Nd: yag laser with a wavelength (530) nm and energy (300, 500, 700) mJ and for two times exposing 20 and 30 seconds by six coefficients and control sample, the low-density diode (5 mW) for 3 times 10, 20 and 30 seconds on distance 20 cm with three treatments and a control sample. DNA was extracted from the fungus after direct exposure and after leaving it to grow for a whole generation and then was used to complete RAPD reactions using five primers. The RAPD marker gave excellent results with all primers, It was noted that the exposure of T. rubrum to the Nd: yag and Diode lasers with different cards and times had different effects on DNA and caused significant changes in the RAPD patterns compared with the control group, new bands appear and others disappear. The energy affecting the fungus T.rubrum for the first laser Nd: yag is 500 mj at time 30 sec while the power of the laser Diode was 5 mw at time 20 sec. The results suggested that the diode laser is highly effective and has a great effect on the genetic material of fungi compared with the effect of the first laser. The conclusion that the use of laser can affect DNA of skin fungi and may lead to mutations which means that it can be used in the treatment of skin fungal infections and the RAPD was effective in detecting the effect of laser at the molecular level as a simple, and inexpensive.
http://dx.doi.org/10.25130/tjps.24.2019.117
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Park, Chan, e Sang Wook Rhee. "The effect of combined application of argon and Nd-YAG lasers on iridectomy in rabbits". Korean Journal of Ophthalmology 3, n. 2 (1989): 47. http://dx.doi.org/10.3341/kjo.1989.3.2.47.
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Al-doori1, Aidah Abd, Awatef Saber Jasem1 e Adnan F. AL-Azzawie2. "Effects of Nd:Yag Laser on some virulence factor genes of Pseudomonas aeruginosa bacteria". Tikrit Journal of Pure Science 25, n. 2 (17 marzo 2020): 86. http://dx.doi.org/10.25130/j.v25i2.962.
Testo completoAbstract (sommario):
The aim of this study was to assess effects of the 532nm Nd-yag laser on the genes of Tox A, Exo S, and Opr L, of Pseudomonas aeruginosa (P. aeruginosa) bacteria isolated from clinical (wounds, burns, otitis media) and environmental (water, soil) samples. Clinical samples were collected from patients coming to Saladdin General Hospital from wound, burns and middle ear infections while environmental samples were extracted from water and soil for Saladdin General Hospital . Bacterial samples irradiated by Nd-Yag laser with wavelength of 532 nm using energies (300mj,500mj) with (15 and 25 sec) and genomic DNA were extracted from all samples after the diagnosis of P. aeruginosa bacteria depending on the macroscopic and biochemical examination, then the PCR technique was performed. The results have shown an impact on P. aeruginosa bacteria of Nd-Yag laser by comparing PCR results of treated samples with control (unexposed) as loss of normal bands. This indicates that the laser had a genetic effect on the P. aeruginosa bacteria. We conclude that the laser induces genetic changes in P. aeruginosa's DNA so that lasers can be used in treatment and sterilization for clinical and environmental . The PCR technique could be used as a biomarker study to determine the biological effects of radiation on bacteria.
http://dx.doi.org/10.25130/tjps.25.2020.034
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Yaniv, Eitan, Tuvia Hadar, Jacob Shvero, Rami Tamir e Ben Nageris. "KTP/532 YAG Laser Treatment for Allergic Rhinitis". American Journal of Rhinology & Allergy 23, n. 5 (settembre 2009): 527–30. http://dx.doi.org/10.2500/ajra.2009.23.3346.
Testo completoAbstract (sommario):
Background The purpose of this study was to investigate the efficacy of the KTP/532 YAG laser to reduce nasal congestion and discharge in patients with allergic rhinitis. Methods Forty-eight patients with symptoms of allergic rhinitis were treated with the KTP/532 laser. All had positive skin tests for common allergens. Treatments were provided on an ambulatory basis in one to three sessions under local anesthesia with lidocaine nose spray. Outcome was determined by daily symptom reports and regular endoscopy examination and interviews for 12 months. Results Treatment was very well tolerated. There were no major side effects. At examination after 1 year, nasal obstruction was improved in 69% and nasal discharge in 40% of cases. Conclusion The KTP/532 YAG laser is effective for the treatment of nasal obstruction and discharge. Comparison with other techniques showed it to be the most effective in reducing nasal discharge. It can be done as an office procedure and does not damage the nasal mucous membrane. The KTP/532 YAG laser is effective as an additional treatment for patients refractory to medication.
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Banerjee, Amit Jyoti, Manoja Kumar Biswal, A. K. Lohar, H. Chattopadhyay e Naga Hanumaiah. "Review on experimental study of Nd:YAG laser beam welding, with a focus on aluminium metal matrix composites". International Journal of Engineering & Technology 5, n. 3 (26 agosto 2016): 92. http://dx.doi.org/10.14419/ijet.v5i3.5984.
Testo completoAbstract (sommario):
The demand for high performance materials particularly in aviation and automobile industries gradually increases, CO2 and Nd: YAG lasers are becoming most popular in processing these advanced materials. In this context, one of the most important process is joining by welding. It has been a constant endeavour by researchers to explore various methods and techniques to enhance the process efficiency of autogenous Nd: YAG laser welding of various materials i.e. without any filler materials. In this work, we present a comprehensive review of major research findings for the last decades or so, obtained by researchers about the effect of process parameters on autogenous laser beam welding (LBW) process performance. Main objective of such experimental research was to improve laser weld quality such as tensile strength, weld micro structure, heat affected zone (HAZ), weld penetration etc. In this paper, discussions are also made about different parameter optimisation techniques, design of experiments (DOE), modelling and simulation techniques, adopted by different researchers to achieve optimum weld quality. This review tries to bring out a foresight for direction of further research needed in this field.
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Firoozeh, Karimi Moghadam. "Study of End Surfaces’ Deformation and Thermal Stress in Solid State Laser". Applied Mechanics and Materials 110-116 (ottobre 2011): 4140–44. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.4140.
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High power solid state lasers have wide applications; they have extensively attracted many attentions. When laser pumped, a lot of heat produces in it causes thermal effects such as stresses end effect and variations of refraction index. In this paper, we analytically study the thermal effects in an Nd: YAG solid state laser crystal which is pumped in longitude with a second order Gaussian (super Gaussian) profile. In this survey we neglect z derivatives of temperature distribution and also consider a statement in which thermal condition of cooler system is much more than thermal condition of laser crystal. Then we apply proper boundary conditions to probe thermal distribution function and related thermal effects. It will be shown that use of second order Gaussian profile for output beam of diode lasers is a better approximation for calculating the thermal distribution and estimating the thermal lensing than the Gaussian profile.
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Mordon, S. R., A. H. Cornil, J. M. Brunetaud, B. Gosselin e Y. Moschetto. "Nd-YAG laser thermal effect: Comparative study of coagulation in rat liver in vivo by continuous wave and high power pulsed lasers". Lasers in Medical Science 2, n. 4 (dicembre 1987): 285–94. http://dx.doi.org/10.1007/bf02594173.
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Ali, Nida Hassan. "Effects of Q-switched Nd: YAG laser irradiation on the aqueous solution of human albumin and calf-thymus double strand DNA (ctds)". Iraqi Journal of Physics (IJP) 13, n. 28 (4 febbraio 2019): 100–105. http://dx.doi.org/10.30723/ijp.v13i28.247.
Testo completoAbstract (sommario):
Q-switched lasers widely used in management skin diseases andsometimes its effect may be inadequate or associated withcytotoxicity. The current study aimed to investigate the effect ofQ-switched Nd:YAG laser upon cellular elements using in vitroexperimental model. Aqueous solutions of human albumin and purecalf thymus double strand deoxyribonucleic acid (ctdsDNA)irradiated with Q-switched Nd:YAG laser at different rates (1, 3 Hz)and time exposure (up to 60 seconds) using 532 nm (400 mJ) and1064 (1200 mJ) nm wavelength with fixed spot size of 4 mm. Theeffect of laser irradiation on the albumin solution also studied in thepresence of elemental salts of copper, zinc and iron.Q-switched laser irradiation at 532 nm produced albumin moleculedamage that potentiated by copper sulfate and variable effect withzinc sulfate. Iron salt stabilized the effect of laser irradiation uponalbumin molecule. The effect of laser irradiation at 1064 nm is lessthan that observed with 532 nm wavelength. ctdsDNA strands aremore susceptible to Q-switched Nd:YAG laser radiation whenexposed at 532 nm with pulse rate of 3Hz. It concludes that usingQ-switched Nd:YAG laser is safe upon the c
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Rezazadeh, Fahimeh, Paria Dehghanian e Dana Jafarpour. "Laser Effects on the Prevention and Treatment of Dentinal Hypersensitivity: A Systematic Review". Journal of Lasers in Medical Sciences 10, n. 1 (15 dicembre 2018): 1–11. http://dx.doi.org/10.15171/jlms.2019.01.
Testo completoAbstract (sommario):
Introduction: Dentinal hypersensitivity (DH) is an acute intensive tooth pain which can lead to dental annoyances during eating and drinking. Stimulating exposed dentinal tubules by either kind of thermal, tactile, chemical and/or osmotic stimuli is believed to be the cause of this pain. It is hypothesized that dentinal tubules’ orifice occlusion (DOO) can help relieve such dental irritations. Thus, this systematic review was conducted to evaluate the effectiveness of laser application as a prevention and treatment modality on DH reduction. Methods: Electronic databases (MEDLINE, SCOPUS) were searched among randomized clinical trials from January 2007 to December 2016. The extraction of data and quality assessments were carried out by different independent observers. Results: A total of 499 items were found of which3 9 relevant articles were extracted. The profound findings proved lasers’ effectiveness as a treatment of DH. Although some of the researches reported no significant difference between laser and other desensitizing agents, most of the studies suggested that better results (both rapid and long-lasting) were obtained in combined modalities. Furthermore, the preventive role of this new technology has been emphasized as well. Nd-YAG (neodymium-doped yttrium aluminum garnet) and diode lasers reduce DH after bleaching. Lasers can also protect cervical restorations from DH due to tubular occlusion. Moreover, it is suggested to apply lasers in relief of DH following scaling and root planning. Nevertheless, a few researchers dispute its beneficence as a result of placebo effect. Conclusion: The results obtained from several studies in the present review revealed that the application of lasers is effective not only in terms of treatment of DH, but also in the prevention of this intensive tooth pain. Among various types of lasers, the application of Nd:YAG laser has shown the best results in DH treatment.
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Mohanty, Nalinikanta, Samir Swain, Arshad Hasan, Gyanprakash Singh e Datteswar Hota. "Determining the correlation between transition zone index with international prostate symptom score and peak flow rate on clinical outcome after transurethral resection of the prostate in benign prostatic hyperplasia". International Surgery Journal 6, n. 12 (26 novembre 2019): 4517. http://dx.doi.org/10.18203/2349-2902.isj20195423.
Testo completoAbstract (sommario):
Background: Benign prostatic hyperplasia (BPH) is a pathologic process which has common contribution to lower urinary tract symptoms (LUTS) in aging men. International Prostate Symptom Score (IPSS) is an important means of assesment in the clinical research of LUTS and BPH. Free flow rates (peak flow rate or Qmax) give an indirect measure for the probability of obstruction whereas subvesical obstruction only can be measured by invasive pressure-flow studies. Among the various surgical or minimally invasive techniques available for BPH like Intraprostatic stents (temporary/permanent), transurethral needle ablation (TUNA), transurethral microwave thermotherapy (TUMT), transurethral electrovaporization of prostate (TUVP), Transurethral incision of prostate (TUIP), lasers (Nd: YAG (Neodymium-doped yttrium aluminium garnet), Ho: YAG (Holmium yttrium aluminium garnet), potassium titanyl phosphate (KTP), diode, thulium laser) etc, transurethral resection of the prostate (TURP) is a safe and effective procedure. Comparison of difference in the pre and postoperative ultrasonic prostatic volume with amount of tissue resected at operation has established the accuracy of the method. The aims of present study are to determine the correlation between transition zone index with international prostate symptom score (IPSS) and peak flow rate (Qmax) on clinical outcome after TURP in BPH patients.Methods: A prospective study was conducted to determine the effect of the extent of tissue resection on symptom improvement after TURP in men and to evaluate any potential correlation between prostate size and outcome.Results: Total of 52 patients studied prospectively. Transitional zone (TZ) index was found to have a significant correlation with the clinical outcome.Conclusions: Symptomatic improvement after TURP will depend on the amount of tissue resected in terms of IPSS and peak flow rates.
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El-Agmy, Reda M., e Najm M. Al-Hosiny. "Thermal analysis and CW laser operation at 1.998 µm in end pumped Tm:YAP lasers". Photonics Letters of Poland 11, n. 4 (31 dicembre 2019): 103. http://dx.doi.org/10.4302/plp.v11i4.938.
Testo completoAbstract (sommario):
We report on thermal analysis and a continuous wave (CW) laser operation at (1.998µm) of end pumped Tm: YAP cylindrical laser rod. The Tm: YAP laser rod is pumped at a wavelength of 1.064 µm emitting from Nd: YAG laser source. A 3W incident pump power is used to generate a maximum laser output of 700 mW, representing 18% slope efficiency. The power of thermally induced lens in Tm:YAP laser rod is numerically analyzed and validated experimentally. The focal lengths of the thermally induced lens are directly measured using Shack-Hartmann wavefront sensor. We have detected blue up-conversion fluorescence emission before laser operation at 1.998 µm. The obtained experimental results were in good agreement with the numerical calculations. Full Text: PDF ReferencesI. F. Elder, J. Payne, "Diode-pumped, room-temperature Tm:YAP laser", Applied Optics 36 (33), 8606 (1997) CrossRef Y. Li, B. Yao, Y. Wang, Y. Ju, G. Zhao, Y. Zong, J. Xu, "High efficient diode-pumped Tm:YAP laser at room temperature", Chinese Opt. Lett. 5 (5), 286 (2007). DirectLink H. Ni, S. C. Rand, "Avalanche upconversion in Tm:YALO3", Opt. Lett. 16 (8), 1424 (1991). CrossRef Z. G. Wang, C. W. Song, Y. F. Li, Y. L. Ju, Y. Z. Wang, "CW and pulsed operation of a diode-end-pumped Tm:GdVO4 laser at room temperature", Laser Phys. Lett. 6 (2), 105 (2009). CrossRef Baoquan Yao, Yi Tian, Wei Wang, Gang Li, Yuezhu Wang, "Analysis and compensation of thermal lens effects in Tm:YAP lasers", Chinese Opt. Lett. 8 (10), 996 (2010). CrossRef F. Cornacchia, D. Parisi, C. Bernardini, M. Toncelli, "Efficient, diode-pumped Tm3+:BaY2F8 vibronic laser", Opt. Expr. 12 (9), 1982 (2004). CrossRef Xiaojin Cheng, Mi Fan, Jiandong Cao, Jianhua Shang, "Research on the thermal effect and laser resonator of diode-pumped thin-slab Tm:YAP lasers", Optik 176, 32 (2019). CrossRef W. Koechner, Solid-state Laser Engineering, Springer, (2013). DirectLink https://www.crytur.cz DirectLink http://www.laserlabcomponents.com/ DirectLink R. M. El-Agmy, N.AlHosiny, "2.31 [micro sign]m laser under up-conversion pumping at 1.064 [micro sign]m in Tm3+:ZBLAN fibre lasers", Elect. Lett. 46 (13), 936 (2010). CrossRef R. M. El-Agmy, N. M. Al-Hosiny, "870 mW blue laser emission at 480 nm in a large core thulium doped ZBLAN fiber laser", Laser Phys. 20 (4), 838 (2010). CrossRef R. M. El-Agmy, N. M. Al-Hosiny, "Power scaling of end-pumped Nd:YLF lasers, modeling and experiments", Optik 140, 584 (2017). CrossRef R. M. El-Agmy, N. Al-Hosiny, "Thermal analysis and experimental study of end-pumped Nd: YLF laser at 1053 nm", Photonic sensors 7 (4), 329 (2017). CrossRef S. C. Tidwell, J. F. Seamans, M. S. Bowers, A. K. Cousins, "Scaling CW diode-end-pumped Nd:YAG lasers to high average powers", IEEE J. Quantum Electron. 28, 997 (1992). CrossRef P. J. Hardman, W. A. Clarkson, G. J. Friel, M. Pollnau, D. C. Hanna, "Energy-transfer upconversion and thermal lensing in high-power end-pumped Nd:YLF laser crystals", IEEE Journal of Quantum Electronics 35, 647 (1999). CrossRef
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Tillová, Eva, e Mária Chalupová. "Unconventional Metallographic Methods for the Structural Characterization of Laser Hardened Al-Zn-Si Cast Alloy". Materials Science Forum 782 (aprile 2014): 369–72. http://dx.doi.org/10.4028/www.scientific.net/msf.782.369.
Testo completoAbstract (sommario):
The laser surface hardening is method which provides increased mechanical properties of secondary (recycled) Al-Si cast alloys for automotive industry. Improvement of mechanical properties and structure of secondary aluminium alloys can often significantly increase the lifetime of casting and reduce costs for fuel and reduction of environmental loading. For study was used a laser beam Nd: YAG lasers, BLS 720, on the test samples of secondary cast alloy AlZn10Si8Mg. AlZn10Si8Mg cast alloy are used for engine and vehicle constructions, hydraulic unit and mould making without the need of heat treatment because this alloy is self-hardened. The effect of laser beam was evaluated with the laser power 50 W and 80 W on the surface of samples. The final microstructure of Al-alloys depend on the laser process parameters. The changes of microstructure after laser surface hardening was observed by using classical techniques of etching (standard black-white contrast - etching by 0.5 % HF, 10 % H3PO4and colour contrast - etching by Weck-Al) and deep etching with HCl. Due to the action of laser beam on the surface of the secondary alloy AlZn10Si8Mg there have been changes in the microstructure of the material. Melting area is alpha-phase with much fine columnar dendrites morphology without the presence of Si-particles and intermetallic phases. In the transition area were observed grain refinement of eutectic Si (finer and rounder Si particles) as the modify action of the laser. By increasing the laser power the microhardness of surface layers decreases. In the surface layer (80 W) were observed cracks due to uneven heat transfer of the material.
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Paul, A. J., D. W. Bonnell, J. W. Hastie, P. K. Schenck, R. D. Shull e J. J. Ritter. "In Situ Characterization of the Pulsed Laser Deposition of Magnetic Thin Films". MRS Proceedings 235 (1991). http://dx.doi.org/10.1557/proc-235-867.
Testo completoAbstract (sommario):
ABSTRACTPulsed Laser Deposition (PLD) has been proven as an effective means of depositing films from refractory targets. In our earlier work, either Nd/YAG or excimer lasers, interacting directly with target surfaces, were used to deposit thin films of high Tc superconductors, high dielectric constant BaTiO3 and ferroelectric PbZr0.53Ti0.47Os3 (PZT). Time-resolved molecular beam mass spectrometry and optical emission spectroscopic techniques have been developed to characterize the vapor plumes responsible for film formation. More recently, this work has been extended to the PLD of magnetic thin films of Ag-Fe3O4 nanocomposites using excimer (ArF*, 193 nm) laser excitation. Optical emission spectra of the excited vapor phase species, formed during the plume generation and material deposition process, indicate that physically compressed powdered metal targets have inadequate homogeneity for film production, compared to targets that are chemically produced. An in situ Laser-induced Vaporization Mass Spectrometry (LVMS) technique utilizing a Nd/YAG (1064 nm) laser has been used to determine Time-of-Arrival (TOA) profiles of the atomic, molecular, and ionic species produced in the plumes of Ag-Fe3O4 The neutral species TOA profiles indicate velocity distributions that are multimodal and not Maxwellian. These observations are in contrast to the TOA profiles observed from one-component targets (Ag or Fe3O4), where a single Maxwellian velocity distribution is found. Mossbauer effect measurements of the thin films have been made for correlation with the gas phase studies.
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Paul, A. J., D. W. Bonnell, J. W. Hastie, P. K. Schenck, R. D. Shull e J. J. Ritter. "In Situ Characterization of the Pulsed Laser DepositIon of Magnetic Thin Films". MRS Proceedings 236 (1991). http://dx.doi.org/10.1557/proc-236-455.
Testo completoAbstract (sommario):
AbstractPulsed Laser Deposition (PLD) has been proven as an effective means of depositing films from refractory targets. In our earlier work, either Nd/YAG or excimer lasers, interacting directly with target surfaces, were used to deposit thin films of high Tc superconductors, high dielectric constant BaTiO3 and ferroelectric PbZr0.53Ti0.47O3 (PZT). Time-resolved molecular beam mass spectrometry and optical emission spectroscopic techniques have been developed to characterize the vapor plumes responsible for film formation. More recently, this work has been extended to the PLD of magnetic thin films of Ag- Fe3O4 nanocomposites using excimer (ArF*, 193 nm) laser excitation. Optical emission spectra of the excited vapor phase species, formed during the plume generation and material deposition process, indicate that physically compressed powdered metal targets have inadequate homogeneity for film production, compared to targets that are chemically produced. An in situ Laser-induced Vaporization Mass Spectrometry (LVMS) technique utilizing a Nd/YAG (1064 nm) laser has been used to determine Time of-Arrival (TOA) profiles of the atomic, molecular, and ionic species produced in the plumes of Ag-Fe3O4. The neutral species TOA profiles indicate velocity distributions that are multimodal and not Maxwellian. These observations are in contrast to the TOA profiles observed from one-component targets (Ag or Fe3O4), where a single Maxwellian velocity distribution is found. Mössbauer effect measurements of the thin films have been made for correlation with the gas phase studies.