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Sample records for laser thermal therapy

  1. Intravenous Laser Therapy in Young Children with Thermal Injuries

    Directory of Open Access Journals (Sweden)

    R. V. Bocharov

    2014-01-01

    Full Text Available Objective: to evaluate the laboratory and clinical effects of combined intravenous laser therapy in young children with thermalinjuries in the acute period of burn disease.Subjects and methods. Forty children whose mean age was 2.67±0.35 years were examined; thermal injuries accounted for 25.05±1.01% of the total body surface area; of them degrees IIIaIIIb was 19.04±0.85%. A comparison group (n=15 received conventional therapy without taking into account and correcting baseline and current hemostasiological disorders. On day 1, a study group (n=25 had programmed anticoagulant therapy and intravenous laser therapy at different radiation frequencies with a Mustang 20002+ laser therapy apparatus (patent for invention No. 2482894 in addition to the conventional therapy. The laser therapy cycle was 6 to 16 sessions. The investigators estimated and compared the following examined parameters: white blood cell count; leukocytic index of intoxication; plasma average mass molecules at a wavelength of 254 nm; toxogenic granularity of neutrophils; wound exudate discharge time; surgical plasty area; and hospitalization time.Results. The positive laboratory and clinical effects of the performed combined intravenous laser therapy in the combined therapy of burn disease in young children were comparatively shown in the study group patients. The significant decrease in the level of an inflammatory response and endogenous intoxication led to a rapider burn wound cleansing, active epithelization, and reduced surgical plasty volumes.Conclusion. Combined intravenous laser therapy signif icantly exerts antiinflammatory and detoxifying effects in young children with 40% thermal injuries in the acute period of burn disease. Abolishing a systemic inflammatory response by combined intravenous laser therapy initiated early regenerative processes in the burn wound and caused reductions in surgical plasty volumes and hospitalization time, which optimizes ther

  2. 1125-nm quantum dot laser for tonsil thermal therapy

    Science.gov (United States)

    McMillan, Kathleen

    2011-03-01

    Thermal therapy has the potential to provide a nonexcisional alternative to tonsillectomy. Clinical implementation requires that the lymphoid tissue of tonsils is heated homogeneously to produce an amount of primary thermal injury that corresponds to gradual postoperative tonsil shrinkage, with minimal risk of damage to underlying critical blood vessels. Optical constants are derived for tonsils from tissue components and used to calculate the depth of 1/e of irradiance. The 1125 nm wavelength is shown to correspond to both deep penetration and minimal absorption by blood. A probe for tonsil thermal therapy that comprises two opposing light emitting, temperature controlled surfaces is described. For ex vivo characterization of tonsil heating, a prototype 1125 nm diode laser is used in an experimental apparatus that splits the laser output into two components, and delivers the radiation to sapphire contact window surfaces of two temperature controlled cells arranged to irradiate human tonsil specimens from opposing directions. Temperatures are measured with thermocouple microprobes at located points within the tissue during and after irradiation. Primary thermal damage corresponding to the recorded thermal histories are calculated from Arrhenius parameters for human tonsils. Results indicate homogeneous heating to temperatures corresponding to the threshold of thermal injury and above can be achieved in advantageously short irradiation times.

  3. Endoscopic laser ablation of clival chordoma with magnetic resonance-guided laser induced thermal therapy

    OpenAIRE

    2014-01-01

    Background: Chordomas are rare malignant tumors that are difficult to treat and have high recurrence rates despite aggressive therapy. Objectives: We present the first case of a patient with a clival chordoma in which complete tumor ablation was achieved using Magnetic Resonance guided Laser Induced Thermal Therapy (LITT) delivered via an endoscopic endonasal approach. We analyzed the safety and feasibility of this approach and quantified the response of this pathology to thermal energy. T...

  4. Laser Interstitial Thermal Therapy Technology, Physics of Magnetic Resonance Imaging Thermometry, and Technical Considerations for Proper Catheter Placement During Magnetic Resonance Imaging-Guided Laser Interstitial Thermal Therapy.

    Science.gov (United States)

    Patel, Nitesh V; Mian, Matthew; Stafford, R Jason; Nahed, Brian V; Willie, Jon T; Gross, Robert E; Danish, Shabbar F

    2016-12-01

    Laser-induced thermal therapy has become a powerful tool in the neurosurgical armamentarium. The physics of laser therapy are complex, but a sound understanding of this topic is clinically relevant, as many centers have incorporated it into their treatment algorithm, and educated patients are demanding consideration of its use for their disease. Laser ablation has been used for a wide array of intracranial lesions. Laser catheter placement is guided by stereotactic planning; however, as the procedure has popularized, the number of ways in which the catheter can be inserted has also increased. There are many technical nuances for laser placement, and, to date, there is not a clear understanding of whether any one technique is better than the other. In this review, we describe the basic physics of magnetic resonance-guided laser-induced thermal therapy and describe the several common techniques for accurate Visualase laser catheter placement in a stepwise fashion.

  5. Laser neurosurgery: A systematic analysis of magnetic resonance-guided laser interstitial thermal therapies.

    Science.gov (United States)

    Lagman, Carlito; Chung, Lawrance K; Pelargos, Panayiotis E; Ung, Nolan; Bui, Timothy T; Lee, Seung J; Voth, Brittany L; Yang, Isaac

    2017-02-01

    Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) is a novel minimally invasive modality that uses heat from laser probes to destroy tissue. Advances in probe design, cooling mechanisms, and real-time MR thermography have increased laser utilization in neurosurgery. The authors perform a systematic analysis of two commercially available MRgLITT systems used in neurosurgery: the Visualase® thermal therapy and NeuroBlate® Systems. Data extraction was performed in a blinded fashion. Twenty-two articles were included in the quantitative synthesis. A total of 223 patients were identified with the majority having undergone treatment with Visualase (n=154, 69%). Epilepsy was the most common indication for Visualase therapy (n=8 studies, 47%). Brain mass was the most common indication for NeuroBlate therapy (n=3 studies, 60%). There were no significant differences, except in age, wherein the NeuroBlate group was nearly twice as old as the Visualase group (p<0.001). Frame, total complications, and length-of-stay (LOS) were non-significant when adjusted for age and number of patients. Laser neurosurgery has evolved over recent decades. Clinical indications are currently being defined and will continue to emerge as laser technologies become more sophisticated. Head-to-head comparison of these systems was difficult given the variance in indications (and therefore patient population) and disparate literature.

  6. Gold nanoshell thermal confinement of conformal laser thermal therapy in liver metastasis

    Science.gov (United States)

    Elliott, Andrew M.; Wang, James; Shetty, Anil M.; Schwartz, Jon; Hazle, John D.; Stafford, R. Jason

    2008-02-01

    Cooled fiber tip technology has significantly improved the volume coverage of laser induced thermal therapy (LITT), making LITT an attractive technology for the minimally invasive treatment of cancer. Gold coated nanoshells can be tuned to experience a plasmon resonance at a desired laser frequency, there introduction into the treatment region can greatly amplify the effectiveness of the thermal treatment. The goal is to conformaly heat the target, while sparing surrounding healthy tissue. To this end a treatment option that is self-confining to the target lesion is highly desirable. This can be achieved in the liver by allowing nanoshells to be taken up by the healthy tissue of the liver as part of their natural removal from the blood stream. The lesion is then incased inside the nanoshell laden tissue of the surrounding healthy tissue. When an interstitial laser probe is introduced into the center of the lesion the thermal radiation scatters outward until it interacts with and is absorbed by the nanoshells located around the lesion periphery. As the periphery heats it acts as secondary source of thermal radiation, sending heat back into lesion and giving rise to ablative temperatures within the lesion while sparing the surrounding tissue. In order to better monitor therapy and know when the target volume has been ablated, or exceeded, accurate knowledge is needed of both the spatial distribution of heating and the maximum temperature achieved. Magnetic resonance temperature imaging (MRTI) is capable of monitoring the spatiotemporal distribution of temperature in vivo[1]. Experiments have been performed in vitro using a dog liver containing nanoshells (concentration 860ppm) and a tissue like lesion phantom designed to have the optical properties of liver metastasis [2].

  7. Laser treatment for liver metastases : thermal and photodynamic therapy

    OpenAIRE

    van Hillegersberg, Richard

    1993-01-01

    textabstractMedical laser applications are one of the points of interest of the Department of Surgery of the Erasmus University Rotterda._"Il. In 1988. experiments were conducted at the Laboratory for Experimental Surgery to investigate the use of laser in destroying liver metastases. These studies led to the research program "Laser treatment of experimental liver metastases", that was supported by the Netherlands Digestive Disease Foundation from beginning 1990 to the middle of 1992. Within ...

  8. Laser treatment for liver metastases : thermal and photodynamic therapy

    NARCIS (Netherlands)

    R. van Hillegersberg (Richard)

    1993-01-01

    textabstractMedical laser applications are one of the points of interest of the Department of Surgery of the Erasmus University Rotterda._"Il. In 1988. experiments were conducted at the Laboratory for Experimental Surgery to investigate the use of laser in destroying liver metastases. These studies

  9. Endoscopic laser ablation of clival chordoma with magnetic resonance-guided laser induced thermal therapy

    Directory of Open Access Journals (Sweden)

    James Barrese

    2014-12-01

    Conclusion: The endoscopic endonasal approach to MRI-guided laser ablation is both technically feasible and safe. As a result, this therapy may be a useful alternative in hard-to-reach chordomas, or in recurrent cases that have failed other conventional treatment modalities.

  10. Bevacizumab (Avastin and Thermal Laser Combination Therapy for Peripapillary Choroidal Neovascular Membranes

    Directory of Open Access Journals (Sweden)

    Sean D. Adrean

    2017-01-01

    Full Text Available Objective. This is a retrospective interventional case series describing the results of 5 eyes from 5 patients with symptomatic peripapillary choroidal neovascularization (CNVM receiving initial bevacizumab treatment followed by thermal laser and bevacizumab combination therapy. Methods. Patients received intravitreal bevacizumab injections until the lesions were well-defined. Thermal laser ablation was then administered and followed by an additional bevacizumab injection after one week. Visual outcomes, OCT changes, and rates of recurrence were recorded and analyzed. Results. Median visual outcomes improved from 20/50 to 20/30 (p=0.0232. Median central macular thickness decreased from 347 μm to 152 μm (p=0.0253. The mean visual improvement was 3 lines. An average of 3.8 bevacizumab injections per patient were given overall. Patients were followed for an average of 24 months, during which all eyes were absent for recurrence. Conclusion. Symptomatic peripapillary CNVM may be successfully managed with bevacizumab followed by a combination of thermal laser and bevacizumab without the need for frequent retreatment. The area requiring treatment may be better defined using bevacizumab, limiting the ablation of the healthy retina and improving treatment margins. With this treatment regimen, the patients experience improved visual outcomes and have a low rate of recurrence.

  11. Assessment of irrigation dynamics in magnetic-resonance guided laser induced thermal therapy (MRgLITT).

    Science.gov (United States)

    Sinha, Saurabh; Hargreaves, Eric; Patel, Nitesh V; Danish, Shabbar F

    2015-03-01

    Magnetic-Resonance Guided Laser-Induced Thermal Therapy (MRgLITT) is a minimally-invasive ablation procedure for treating intracranial pathology using laser energy delivered through a fiber-optic. Saline irrigation is used to cool the fiber-optic, but factors affecting irrigation efficacy are not well studied, and quantitative information regarding irrigation speed and volume during MRgLITT procedures have not been reported. Here, we aimed to characterize variables affecting irrigation efficacy in MRgLITT. We investigated the irrigation setup of the Visualase thermal therapy system during MRgLITT procedures (Visualase Inc., Houston, TX). Using the system's peristaltic pump, irrigation flow rate was quantitated by measuring volume over five one-minute intervals. Pump settings 1-10 were assessed with and without the position-locking, resistance-imparting bone anchor in both single and double-catheter setups. Multiple tightness settings of the bone anchor were tested, and flow rates were analyzed. Rate of flow increased non-linearly with pump setting (F(1,4) = 2168.86; P irrigation speeds in achieving optimal ablation volumes. © 2015 Wiley Periodicals, Inc.

  12. Laser interstitial thermal therapy for subependymal giant cell astrocytoma: technical case report.

    Science.gov (United States)

    Dadey, David Y A; Kamath, Ashwin A; Leuthardt, Eric C; Smyth, Matthew D

    2016-10-01

    Subependymal giant cell astrocytoma (SEGA) is a rare tumor occurring almost exclusively in patients with tuberous sclerosis complex. Although open resection remains the standard therapy, complication rates remain high. To minimize morbidity, less invasive approaches, such as endoscope-assisted resection, radiosurgery, and chemotherapy with mTOR pathway inhibitors, are also used to treat these lesions. Laser interstitial thermal therapy (LITT) is a relatively new modality that is increasingly used to treat a variety of intracranial lesions. In this report, the authors describe two pediatric cases of SEGA that were treated with LITT. In both patients the lesion responded well to this treatment modality, with tumor shrinkage observed on follow-up MRI. These cases highlight the potential of LITT to serve as a viable minimally invasive therapeutic approach to the management of SEGAs in the pediatric population.

  13. Laser therapy for cancer

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000905.htm Laser therapy for cancer To use the sharing features ... Lasers are also used on the skin. How Laser Therapy is Used Laser therapy can be used ...

  14. Thermal ablation of liver metastases from colorectal cancer: radiofrequency, microwave and laser ablation therapies.

    Science.gov (United States)

    Vogl, Thomas J; Farshid, Parviz; Naguib, Nagy N N; Darvishi, Abbas; Bazrafshan, Babak; Mbalisike, Emmanuel; Burkhard, Thorsten; Zangos, Stephan

    2014-07-01

    Surgery is currently considered the treatment of choice for patients with colorectal cancer liver metastases (CRLM) when resectable. The majority of these patients can also benefit from systemic chemotherapy. Recently, local or regional therapies such as thermal ablations have been used with acceptable outcomes. We searched the medical literature to identify studies and reviews relevant to radiofrequency (RF) ablation, microwave (MW) ablation and laser-induced thermotherapy (LITT) in terms of local progression, survival indexes and major complications in patients with CRLM. Reviewed literature showed a local progression rate between 2.8 and 29.7 % of RF-ablated liver lesions at 12-49 months follow-up, 2.7-12.5 % of MW ablated lesions at 5-19 months follow-up and 5.2 % of lesions treated with LITT at 6-month follow-up. Major complications were observed in 4-33 % of patients treated with RF ablation, 0-19 % of patients treated with MW ablation and 0.1-3.5 % of lesions treated with LITT. Although not significantly different, the mean of 1-, 3- and 5-year survival rates for RF-, MW- and laser ablated lesions was (92.6, 44.7, 31.1 %), (79, 38.6, 21 %) and (94.2, 61.5, 29.2 %), respectively. The median survival in these methods was 33.2, 29.5 and 33.7 months, respectively. Thermal ablation may be an appropriate alternative in patients with CRLM who have inoperable liver lesions or have operable lesions as an adjunct to resection. However, further competitive evaluation should clarify the efficacy and priority of these therapies in patients with colorectal cancer liver metastases.

  15. MRI-guided laser interstitial thermal therapy in neuro-oncology: a review of its current clinical applications.

    Science.gov (United States)

    Rahmathulla, Gazanfar; Recinos, Pablo F; Kamian, Kambiz; Mohammadi, Alireza M; Ahluwalia, Manmeet S; Barnett, Gene H

    2014-01-01

    Magnetic resonance imaging-guided laser interstitial thermal therapy (LITT) is a minimally invasive treatment modality with recent increasing use to ablate brain tumors. When originally introduced in the late 1980s, the inability to precisely monitor and control the thermal ablation limited the adoption of LITT in neuro-oncology. Popularized as a means of destroying malignant hepatic and renal metastatic lesions percutaneously, its selective thermal tumor destruction and preservation of adjacent normal tissues have since been optimized for use in neuro-oncology. The progress made in real-time thermal imaging with MRI, laser probe design, and computer algorithms predictive of tissue kill has led to the resurgence of interest in LITT as a means to ablate brain tumors. Current LITT systems offer a surgical option for some inoperable brain tumors. We discuss the origins, principles, current indications, and future directions of MRI-guided LITT in neuro-oncology.

  16. Low power argon laser-induced thermal therapy for subcutaneous Ehrlich carcinoma in mice using spherical gold nanoparticles.

    Science.gov (United States)

    Elbialy, Nihal; Abdelhamid, Mahmoud; Youssef, Tareq

    2010-12-01

    The present study examines the feasibility of a low power argon laser-induced thermal therapy to Ehrlich carcinoma, employing a direct administration of spherical gold nanoparticles (GNPs). This modality utilizes the advantage of strong surface plasmon resonance exhibited by spherical GNPs in the visible range. Ehrlich tumors were grown in female balb mice by subcutaneous injection of Ehrlich ascites carcinoma cells. GNPs with an average diameter 13 +/- 1.2 nm and optical density (ODlambda:518 nm = 3) were directly injected within the tumor interstitium. Tumors were then illuminated with a continuous-wave (CW) argon ion laser with irradiance 55 mW cm-2 for 45 min. All laser-GNPs treated tumors exhibited a significant suppression in tumor growth throughout 15 days. On the contrary, sham-treated group (laser treatment without GNPs injection) and control group (neither laser nor GNPs treatment) showed a progressive increase in tumor growth during the same period. Histopathological examination demonstrated extensive necrotic percentage in laser-GNPs treated group (90%) in comparison with sham (35%) or control group (3-7%). A wide-angle X-ray scattering also revealed detectable changes in tumor protein structure exposed to both laser and GNPs. It can be concluded from this study that the intense surface plasmon resonance exhibited by spherical GNPs in the visible range could be very useful as a noninvasive technique for photothermal therapy of skin or near-surface type tumors that need much less laser energy and lower concentrations of GNPs.

  17. Simulation of nanosecond laser-induced thermal dynamics of hollow gold nanoshells for hyperthermia therapy

    Energy Technology Data Exchange (ETDEWEB)

    Hatef, Ali, E-mail: michel.meunier@polymtl.ca; Fortin-Deschênes, Simon, E-mail: michel.meunier@polymtl.ca; Meunier, Michel, E-mail: michel.meunier@polymtl.ca [Laser Processing and Plasmonics Laboratory, Department of Engineering Physics, École Polytechnique de Montréal, Montréal, Québec, H3C 3A7 (Canada)

    2014-03-31

    In this report, we investigate numerically the thermodynamics of hollow gold nanoshell (AuNS) irritated by near-infrared (NIR) light. Simulations are performed for the AuNS in aqueous medium. The nanostructure is illuminated by a nanosecond pulsed laser at plasmonic resonance. The spatiotemporal evolution of the temperature profile inside and outside the AuNS is computed using a numerical framework based on the finite element method (FEM). In particular, we show how the temperature varies with the laser fluence and pulse duration. The aim of this study is to provide a description of the physics of heat release of AuNSs and useful insights for the development of these nanostructures for biomedical applications such as drug delivery, photothermal cancer therapy and optoporation of cells.

  18. Simulation of nanosecond laser-induced thermal dynamics of hollow gold nanoshells for hyperthermia therapy

    Science.gov (United States)

    Hatef, Ali; Fortin-Deschênes, Simon; Meunier, Michel

    2014-03-01

    In this report, we investigate numerically the thermodynamics of hollow gold nanoshell (AuNS) irritated by near-infrared (NIR) light. Simulations are performed for the AuNS in aqueous medium. The nanostructure is illuminated by a nanosecond pulsed laser at plasmonic resonance. The spatiotemporal evolution of the temperature profile inside and outside the AuNS is computed using a numerical framework based on the finite element method (FEM). In particular, we show how the temperature varies with the laser fluence and pulse duration. The aim of this study is to provide a description of the physics of heat release of AuNSs and useful insights for the development of these nanostructures for biomedical applications such as drug delivery, photothermal cancer therapy and optoporation of cells.

  19. An inverse problem approach to recovery of in vivo nanoparticle concentrations from thermal image monitoring of MR-guided laser induced thermal therapy.

    Science.gov (United States)

    Fuentes, D; Elliott, A; Weinberg, J S; Shetty, A; Hazle, J D; Stafford, R J

    2013-01-01

    Quantification of local variations in the optical properties of tumor tissue introduced by the presence of gold-silica nanoparticles (NP) presents significant opportunities in monitoring and control of NP-mediated laser induced thermal therapy (LITT) procedures. Finite element methods of inverse parameter recovery constrained by a Pennes bioheat transfer model were applied to estimate the optical parameters. Magnetic resonance temperature imaging (MRTI) acquired during a NP-mediated LITT of a canine transmissible venereal tumor in brain was used in the presented statistical inverse problem formulation. The maximum likelihood (ML) value of the optical parameters illustrated a marked change in the periphery of the tumor corresponding with the expected location of NP and area of selective heating observed on MRTI. Parameter recovery information became increasingly difficult to infer in distal regions of tissue where photon fluence had been significantly attenuated. Finite element temperature predictions using the ML parameter values obtained from the solution of the inverse problem are able to reproduce the NP selective heating within 5 °C of measured MRTI estimations along selected temperature profiles. Results indicate the ML solution found is able to sufficiently reproduce the selectivity of the NP mediated laser induced heating and therefore the ML solution is likely to return useful optical parameters within the region of significant laser fluence.

  20. Delayed Intraparenchymal and Intraventricular Hemorrhage Requiring Surgical Evacuation after MRI-Guided Laser Interstitial Thermal Therapy for Lesional Epilepsy.

    Science.gov (United States)

    Barber, Sean M; Tomycz, Luke; George, Timothy; Clarke, Dave F; Lee, Mark

    2017-01-01

    Symptomatic intracranial hemorrhage is a rare complication of laser interstitial thermal therapy (LITT). To present a unique case of delayed symptomatic intracranial hemorrhage occurring after a LITT procedure for epilepsy in a high-volume center (68 LITT procedures for pediatric epilepsy have been performed). An 18-year-old male with epilepsy underwent LITT to an area of heterotopia near the right lateral ventricle. He did well initially and was discharged home on postoperative day 1 but returned on postoperative day 9 with headache and left hemiparesis. He was found to have intraparenchymal and intraventricular hemorrhage in the region of the LITT catheter tract. CT angiography on admission revealed a small vascular abnormality near the focus of hemorrhage suspicious for pseudoaneurysm, although conventional angiography was negative. The patient declined neurologically and underwent craniotomy and hemorrhage evacuation. He eventually convalesced and was discharged to inpatient rehabilitation with persistent left hemiparesis. He has been seizure free since the intervention but remains on antiepileptic drugs. Evidence from the literature suggests that the pathophysiology of symptomatic hemorrhage after LITT may be related to vascular injury and pseudoaneurysm formation from LITT catheter placement and/or thermal injury from the ablation itself. © 2017 S. Karger AG, Basel.

  1. [Low reactive laser therapy].

    Science.gov (United States)

    Saeki, Shigeru

    2012-07-01

    The type, characteristics and effect of low reactive laser equipment used for pain treatment in Japan are described in this section. Currently, low reactive laser therapy equipments marketed and used in Japan include diode laser therapeutic device with semiconductor as a medium consisting of aluminum, gallium and arsenic. Low reactive laser equipment comes in three models, the first type has a capacity of generating 1,000 mW output, and the second type has a capacity of generating 10 W output. The third type has four channels of output, 60, 100, 140 and 180 mW and we can select one channel out of the four channels. This model is also used as a portable device because of its light weight, and we can carry it to wards and to the outside of the hospital. Semiconductor laser has the capacity of deepest penetration and the effect tends to increase proportionally to the increasing output. Low reactive laser therapy is less invasive and lower incidence of complications. Although low reactive laser therapy might be effective for various pain disorders, the effect is different depending on the type of pain. We should keep in mind that this therapy will not give good pain relief equally in all patients with pain.

  2. Laser therapy for periodontitis

    Science.gov (United States)

    Efanov, O. I.

    2001-04-01

    An investigation was made of applying pulsed (lambda) equals 0.89 micrometers laser radiation in the treatment for early diagnosed periodontitis. The investigation was made on 65 patients (47 patients constituted the experimental group and 18 patients constituted a control group) affected by periodontitis. Clinical and functional tests revealed that laser therapy produced a string effect on the course of the illness. It reduced bleeding, inflammation, and pruritus. However, it did not produce an affect on electroexcitation. Biomicroscopic examinations and periodontium rheography revealed that the gingival blood flow became normal after the course of laser therapy. The capillary permeability and venous congestion decreased, which was confirmed by the increased time of vacuum tests, raised gingival temperature, reduced tissue clearance, and increased oxygen tension. Apart from that, laser therapy subsided fibrinolysis, proteolytic tissue activity, and decreased the exudative inflammation of periodontium.

  3. Laser Thermal Ablation of Thyroid Benign Nodules.

    Science.gov (United States)

    Shahrzad, Mohammad Karim

    2015-01-01

    Thermal ablation therapies for benign thyroid nodules have been introduced in recent years to avoid the complications of traditional methods such as surgery. Despite the little complications and the reportedly acceptable efficacy of thermal ablation methods, quite few medical centers have sought the potential benefits of employing them. This paper provides an introduction to the literature, principles and advances of Percutaneous Laser Ablation therapy of thyroid benign nodules, as well as a discussion on its efficacy, complications and future. Several clinical research papers evaluating the thermal effect of laser on the alleviation of thyroid nodules have been reviewed to illuminate the important points. The results of this research can help researchers to advance the approach and medical centers to decide on investing in these novel therapies.

  4. Variable emissivity laser thermal control system

    Science.gov (United States)

    Milner, Joseph R.

    1994-01-01

    A laser thermal control system for a metal vapor laser maintains the wall mperature of the laser at a desired level by changing the effective emissivity of the water cooling jacket. This capability increases the overall efficiency of the laser.

  5. [Laser radiations in medical therapy].

    Science.gov (United States)

    Richand, P; Boulnois, J L

    1983-06-30

    The therapeutic effects of various types of laser beams and the various techniques employed are studied. Clinical and experimental research has shown that Helio-Neon laser beams are most effective as biological stimulants and in reducing inflammation. For this reasons they are best used in dermatological surgery cases (varicose ulcers, decubital and surgical wounds, keloid scars, etc.). Infrared diode laser beams have been shown to be highly effective painkillers especially in painful pathologies like postherpetic neuritis. The various applications of laser therapy in acupuncture, the treatment of reflex dermatologia and optic fibre endocavital therapy are presented. The neurophysiological bases of this therapy are also briefly described.

  6. Laser therapy (image)

    Science.gov (United States)

    A laser is used for many medical purposes. Because the laser beam is so small and precise, it enables ... without injuring surrounding tissue. Some uses of the laser are retinal surgery, excision of lesions, and cauterization ...

  7. Thermal lensing of laser materials

    Science.gov (United States)

    Davis, Mark J.; Hayden, Joseph S.

    2014-10-01

    This paper focuses on the three main effects that can induce wave-front distortion due to thermal lensing in laser gain media: 1) thermo-optic (dn/dT); 2) stress-optic; and 3) surface deformation (e.g., "end-bulging" of a laser rod). Considering the simple case of a side-pumped cylindrical rod which is air- or water-cooled along its length, the internal temperature distribution has long been known to assume a simple parabolic profile. Resulting from this are two induced refractive index variations due to thermo-optic and stress-optic effects that also assume a parabolic profile, but generally not of the same magnitude, nor even of the same sign. Finally, a small deformation on the rod ends can induce a small additional lensing contribution. We had two goals in this study: a) use finite-element simulations to verify the existing analytical expressions due to Koechner1 and Foster and Osterink; and b) apply them to glasses from the SCHOTT laser glass portfolio. The first goal was a reaction to more recent work by Chenais et al. who claimed Koechner made an error in his analysis with regard to thermal stress, throwing into doubt conclusions within studies since 1970 which made use of his equations. However, our re-analysis of their derivations, coupled with our FE modeling, confirmed that the Koechner and Foster and Osterink treatments are correct, and that Chenais et al. made mistakes in their derivation of the thermally-induced strain. Finally, for a nominal laser rod geometry, we compared the thermally-induced optical distortions in LG-680, LG-750, LG-760, LG-770, APG-1, and APG-2. While LG-750, -760, and -770 undergo considerable thermo-optic lensing, their stress-optic lensing is nearly of the same magnitude but of opposite sign, leading to a small total thermal lensing signature.

  8. [Thermal lasers and skin cicatrization].

    Science.gov (United States)

    Mordon, Serge; Capon, Alexandre; Fournier, Nathalie; Iarmarcovai, Gwen

    2010-01-01

    Any cutaneous damage triggers a cascade of biological effects in the skin responsible for re-establishing skin integrity. Wound healing is a complex biological process inducing dermal remodelling leading at least to a visible scar, and sometimes to hypertrophic or keloid scars. Recent studies suggest that using a laser generates a precisely defined thermal effect in the skin, improving the wound healing process and potentially opening the door to scarless healing.

  9. Laser therapy of stretch marks.

    Science.gov (United States)

    McDaniel, David H

    2002-01-01

    Striae distensae, better known as stretch marks, are a common disfiguring skin disorder of significant cosmetic concern. Many sources have reported the use of lasers to diminish the appearance of striae. Controlled clinical studies of the various treatment modalities available for striae are relatively uncommon, and much of the clinical data are anecdotal. The use of lasers alone or in combination with other therapeutic modalities can provide a safe and effective reduction in the appearance of both red and white striae distensae. Many of these therapies require special measures for darker skin phototypes. This article reviews the historical use of laser therapy for this disorder and discusses current therapeutic options.

  10. [Laser therapy in orthognatic surgery].

    Science.gov (United States)

    Kimura-Fujikami, Takao; Cabrera-Muñóz, Maria Lourdes; Del Valle-Espinoza, Alejandro

    2005-01-01

    This study describes the prevalence of patients with dentofacial deformities attended in the Maxillofacial Surgery Department of Hospital de Especialidades del Centro Medico Nacional Siglo XXI of the IMSS, during January to December 2002. Twenty-six patients received postoperative laser therapy in the right area of the mandible ramus, after bilateral sagittal modified osteotomy (BSMKSO). The results with laser therapy showed less pain and edema in comparison other patients without this therapy. The results were carried out after 24 hours, 3 days, 8 days and 15 days, and after 10 treatments of laser therapy. The X-Ray and biopsy showed bone healing 30 days, six and eight weeks after orthognatic surgery procedures.

  11. Laser therapy of muscle injuries.

    Science.gov (United States)

    Dawood, Munqith S; Al-Salihi, Anam Rasheed; Qasim, Amenah Wala'a

    2013-05-01

    Low-level lasers are used in general therapy and healing process due to their good photo-bio-stimulation effects. In this paper, the effects of diode laser and Nd:YAG laser on the healing process of practically managed skeletal muscle trauma has been successfully studied. Standard impact trauma was induced by using a specially designed mechanical device. The impacted muscle was left for 3 days for complete development of blunt trauma. After that it was irradiated by five laser sessions for 5 days. Two types of lasers were used; 785-nm diode laser and 1.064-nm Nd:YAG laser, both in continuous and pulsed modes. A special electronic circuit was designed and implemented to modulate the diode laser for this purpose. Tissue samples of crushed skeletal muscle have been dissected from the injured irradiated muscle then bio-chemically analyzed for the regeneration of contractile and collagenous proteins using Lowry assay for protein determination and Reddy and Enwemeka assay for hydroxyproline determination. The results showed that both lasers stimulate the regeneration capability of traumatized skeletal muscle. The diode laser in CW and pulsed modes showed better results than the Nd:YAG in accelerating the preservation of the normal tissue content of collagenous and contractile proteins beside controlling the regeneration of non-functional fibrous tissue. This study proved that the healing achieved by the laser treatment was faster than the control group by 15-20 days.

  12. Laser therapy in ocular tumors

    Science.gov (United States)

    Carstocea, Benone D.; Gafencu, Otilia L.; Apostol, Silvia; Ionita, Marcel A.; Moroseanu, A.; Dascalu, Traian; Lupei, Voicu; Ionita-Manzatu, V.

    1998-07-01

    The medical laser equipments made at NILPRP have been exploited intensively for more than 10 years at CMH. The availability and reliability of the first like-on equipment have increased, following improvements in optical delivery system and cooling circuit. This paper shows the impact of technical advances on the development of ophthalmologic laser therapy. Intraocular tumors pose special problems of diagnosis and treatment. Diagnostic methods include addition to systemic and ophthalmologic examinations, ancillary examinations, such as transillumination, fluorescence angiography, ultrasonography, radioactive phosphorus uptake tests, radiology, computerized tomography and fine-needle aspiration biopsy with cytological analyses. The enucleation of the involved eye used to be a generally accepted management of malignant tumors. Improved therapeutic methods such as photocoagulation and better surgical techniques now provide a variety of therapeutic alternatives. This study covers 31 cases of intraocular tumors that were managed either by Argon Laser photocoagulation and/or by Nd:YAG laser surgical treatment. Four cases were intraocular metastasse and 17 cases were primitive intraocular tumors. Argon laser therapy proved to be totally ineffective for intraocular metastasse but very adequate therapy for primitive tumors. Tumor extirpations (choroidal, cillary body or iris tumors) using Nd:YAG laser lancet proved to be more suitable than classic surgery.

  13. Laser therapy in cardiovascular disease

    Science.gov (United States)

    Rindge, David

    2009-02-01

    Cardiovascular disease is the number one cause of death worldwide. It is broadly defined to include anything which adversely affects the heart or blood vessels. One-third of Americans have one or more forms of it. By one estimate, average human life expectancy would increase by seven years if it were eliminated. The mainstream medical model seeks mostly to "manage" cardiovascular disease with pharmaceuticals or to surgically bypass or reopen blocked vessels via angioplasty. These methods have proven highly useful and saved countless lives. Yet drug therapy may be costly and ongoing, and it carries the risk of side effects while often doing little or nothing to improve underlying health concerns. Similarly, angioplasty or surgery are invasive methods which entail risk. Laser therapy1 regenerates tissue, stimulates biological function, reduces inflammation and alleviates pain. Its efficacy and safety have been increasingly well documented in cardiovascular disease of many kinds. In this article we will explore the effects of laser therapy in angina, atherosclerosis, coronary artery disease, hypertension, hyperlipidemia, myocardial infarction, stroke and other conditions. The clinical application of various methods of laser therapy, including laserpuncture and transcutaneous, supravascular and intravenous irradiation of blood will be discussed. Implementing laser therapy in the treatment of cardiovascular disease offers the possibility of increasing the health and wellbeing of patients while reducing the costs and enhancing safety of medical care.

  14. Laser therapy in intraocular tumors

    Science.gov (United States)

    Carstocea, Benone D.; Gafencu, Otilia L.; Apostol, Silvia

    1995-01-01

    Intraocular tumors present special problems of diagnosis and treatment. Diagnostic methods include, in addition to systemic and ophthalmological examinations, ancillary examinations such as transillumination, fluorescein angiography, ultrasonography, radioactive phosphorus uptake test, radiology, computerized tomography, and fine-needle aspiration biopsy with cytological analyses. Previously, enucleation of the involved eye was generally accepted as management of malignant tumors. Improved therapeutic methods such as photocoagulation and better surgical techniques now provide a variety of therapeutical alternatives. This study consists of 21 cases of intraocular tumors that were managed by Argon laser photocoagulation. Four cases were intraocular metastasis and 17 cases were primitive intraocular tumors. Argon laser therapy proved to be totally ineffective for the intraocular metastasis and a very adequate therapy for the primitive tumors. Tumor extirpations (choroidal, cillary body, or iris tumors) using laser lancet proved to be more suitable than classic surgery.

  15. The regeneration of thermal wound on mice skin (Mus Musculus) after Q-Switch Nd: YAG laser irradiation for cancer therapy candidate

    Science.gov (United States)

    Apsari, R.; Nahdliyatun, E.; Winarni, D.

    2017-09-01

    The aims of this study are to investigate the regeneration of mice skin tissue (Mus Musculus) irradiated by Q-Switch Nd: YAG laser and morphological change due to Q-Switch Nd: YAG laser irradiation compared to conventional heating (hairdryer). The 2-3 month of twenty-seven mice were used for experimental animals. Mice were incised in the dorsum by the damage effect of laser energy dose (therapeutic dose) of 29.5 J/cm2 with 10 seconds of exposure time, 10 Hz of repetition rate, and 100 pulses of the given single pulse energy. The mice skin tissue was injuried by hairdryer to get burned effect. Mice were divided into three groups, Group I (control) were not treated by anything, Group II were treated by Q-Switch Nd: YAG laser irradiation and sacrificed on (0, 1, 3, 5) days, and Group III were treated by hairdryer then sacrificed on (0, 1, 3, 5) days. Pathology examination showed that the energy of 29,5 J/cm2 dose produced the hole effect (ablation) through the hypodermic layer caused by optical breakdown and collagen coagulation. Thus, the 60 °C temperature of burn showed coagulation necrosis because piknosis discovered in the injured area. The regeneration process showed that the mice skin tissue's ability to regenerate was irradiated by fast laser because of the focus of Q-Switch Nd: YAG laser. It was showed by the scab releases on third day and completely reepithelialization formation on the fifth day. The collagen fibers distribution was same as normal skin tissue on day 5 and so did angiogenesis. Therefore, Q-Switch Nd: YAG laser can be applied for problems of dermatology medical therapies, especially melasma, nevus of ota and tatto therapy. For skin cancer therapy application, energy dose of unregenerated skin tissue is chosen because the death expected effect is permanent.

  16. In vitro and in vivo mapping of drug release after laser ablation thermal therapy with doxorubicin-loaded hollow gold nanoshells using fluorescence and photoacoustic imaging.

    Science.gov (United States)

    Lee, Hannah J; Liu, Yang; Zhao, Jun; Zhou, Min; Bouchard, Richard R; Mitcham, Trevor; Wallace, Michael; Stafford, R Jason; Li, Chun; Gupta, Sanjay; Melancon, Marites P

    2013-11-28

    Doxorubicin-loaded hollow gold nanoshells (Dox@PEG-HAuNS) increase the efficacy of photothermal ablation (PTA) not only by mediating efficient PTA but also through chemotherapy, and therefore have potential utility for local anticancer therapy. However, in vivo real-time monitoring of Dox release and temperature achieved during the laser ablation technique has not been previously demonstrated before. In this study, we used fluorescence optical imaging to map the release of Dox from Dox@PEG-HAuNS and photoacoustic imaging to monitor the tumor temperature achieved during near-infrared laser-induced photothermal heating in vitro and in vivo. In vitro, treatment with a 3-W laser was sufficient to initiate the release of Dox from Dox@PEG-HAuNS (1:3:1 wt/wt, 1.32 × 10(12)particles/mL). Laser powers of 3 and 6W achieved ablative temperatures of more than 50°C. In 4T1 tumor-bearing nude mice that received intratumoral or intravenous injections of Dox@PEG-HAuNS, fluorescence optical imaging (emission wavelength = 600 nm, excitation wavelength = 500 nm) revealed that the fluorescence intensity in surface laser-treated tumors 24h after treatment was significantly higher than that in untreated tumors (p = 0.015 for intratumoral, p = 0.008 for intravenous). Similar results were obtained using an interstitial laser to irradiate tumors following the intravenous injection of Dox@PEG-HAuNS (p = 0.002 at t = 24h). Photoacoustic imaging (acquisition wavelength = 800 nm) revealed that laser treatment caused a substantial increase in tumor temperature, from 37 °C to ablative temperatures of more than 50 °C. Ex vivo analysis revealed that the fluorescence intensity of laser-treated tumors was twice as high as that of untreated tumors (p = 0.009). Histological analysis confirmed that intratumoral injection of Dox@PEG-HAuNS and laser treatment caused significantly more tumor necrosis compared to tumors that were not treated with laser (pthermal ablation therapy. © 2013.

  17. Renaissance of laser interstitial thermal ablation

    National Research Council Canada - National Science Library

    Missios, Symeon; Bekelis, Kimon; Barnett, Gene H

    2015-01-01

    .... The development of magnetic resonance thermography and its application to LITT have allowed for real-time thermal imaging and feedback control during laser energy delivery, allowing for precise...

  18. The optimization of laser systems for photodynamic therapy of malignancies

    Science.gov (United States)

    Lim, Hyun S.; Lee, Sang Chan; Kim, Ju Ock

    2005-04-01

    In this paper, we optimized the PDT laser system to improve the therapy effects of malignancies. In order to optimizes, the variation of laser output and specific wavelength shift have to reduced. To improved the PDT therapy clincian require the diverse radiation mode which irradiate the tumor surface. Continuous wave mode that general application may causes tissue thermal damage not only to tumor tissue, but also to nomal tissue. Therefore, we suggested new technique for radiation method to improved PDT effects and prevented to the thermal effects for the tissue. In experimental we verified the stability of wavelength, laser output stability and proved the reduced thermal effects to the tissue using the pulse & burst radiation modes in vitro.

  19. Laser-mediated photodynamic therapy.

    Science.gov (United States)

    Alexiades-Armenakas, Macrene

    2006-01-01

    Photodynamic therapy (PDT) has evolved since its inception at the beginning of the 20th century, when it was defined as an oxygen-dependent reaction between a photosensitizing dye and light. Photosensitizers and light sources have since been continually optimized for distinct applications and tissues. Systemic porphyrins, such as hematoporphyrin, were the first photosensitizers to be used, mostly to treat tumors. The first light sources used were broad-band, noncoherent lights, such as quartz, xenon, tungsten, or halogen lamps. The wavelengths of light chosen were based upon the absorption spectrum of porphyrins: blue because the largest peak is at 400 nm (the Soret band) and red because of its greater penetration depth but lesser absorption at 650 nm (a Q band). Systemic photosensitizers caused prolonged photosensitivity, and broad-band light sources had limitations and side effects. The development of topical photosensitizers, such as 5-aminolevulinic acid, and the advent of lasers in recent years have advanced PDT for cutaneous use. In the 1990s, red lasers were applied to PDT because of their increased skin penetration despite lesser absorption by porphyrins. Broad-band blue light and red light have been studied extensively, the former achieving Food and Drug Administration approval in combination with topical aminolevulinic acid for the treatment of actinic keratosis in 1997. These lasers and light sources caused significant side effects, such as discomfort, erythema, crusting, blistering, and dyspigmentation. The recent application of the long-pulsed pulsed dye laser (595 nm) after topical aminolevulinic acid greatly minimized side effects without compromising efficacy. Long-pulsed pulsed dye laser-mediated PDT has since been shown to be effective in treatment of actinic keratosis, actinic cheilitis, sebaceous hyperplasia, lichen sclerosus, and, most recently, acne vulgaris. Finally, intense pulsed light sources have been introduced to PDT for the treatment

  20. Dodick laser phacolysis: thermal effects.

    Science.gov (United States)

    Alzner, E; Grabner, G

    1999-06-01

    To gather experimental data on whether Dodick laser phacolysis leads to corneal or scleral burns. The Eye Department, County Hospital Salzburg, Salzburg, Austria. The study was done using a pulsed neodymium:YAG (Nd:YAG) laser with a wavelength of 1064 nm; energy, 10 mJ; and duration of pulses, 14 ns. The light pulse is carried by a 400 microns quartz fiber to the laser phacolysis probe. The laser light hits a titanium target inside the tip, causing an optical breakdown and thus a shock wave. The generation of both plasma and the shock disrupt the nuclear material. The temperature at the ultrasonic phaco and laser phacolysis tip was measured under air and balanced salt solution (BSS) in a test chamber and in the anterior chambers of eye-bank eyes. Ultrasonic phacoemulsification led to a difference in temperature up to 55.3 degrees C under air, 12 degrees C in BSS, and 10.9 degrees C in the anterior chamber. There was no clinical significant heat generated by the laser phacolysis tip. This initial in vitro study demonstrates that the well-known risk of the tissue heating (i.e., phaco burn) does not occur with Dodick laser phacolysis, even when the irrigation flow is slow or discontinued.

  1. LASER INDUCED THERMAL LENS EFFECT

    Institute of Scientific and Technical Information of China (English)

    沈俊; 黄孟才; 江景云; 施教芳

    1991-01-01

    The thermal lens effect has emerged in recent years as a novel ,highly sensitive tool for the study of the very weak molecular absorption of light energy,This paper discusses the theory and technique of the thermal lens measurement.Some opplications of the thermal lens measurement are described.A mode-mismatched dual-beam thermal lens experimental arragement with a modulated probe beam ,designed by the authors.for trace analysis is presented,and its detection limit was found to be 4.1×10-7 for Cu(Ⅱ) in ethanol and 80 mW excitation power.

  2. [Use of the thermal laser effect of laser irradiation for cardiovascular applications exemplified by the Nd:YAG laser].

    Science.gov (United States)

    Ischinger, T; Coppenrath, K; Weber, H; Enders, S; Unsöld, E; Hessel, S

    1989-11-01

    Techniques of percutaneous transluminal application of laser energy for vessel recanalization have been used clinically since 1983. The commonly used Nd:YAG and argon lasers achieve ablation of atherosclerotic plaques by thermal action (vaporization). In order to reduce undesirable thermal damage in the neighborhood of the target tissue and to avoid vessel perforation, optimal irradiation parameters, modified (atraumatic) fiber tips (hot tips, sapphires), and steerable catheter systems needed to be implemented. Favorable results from peripheral application have encouraged use in the coronary circulation. More recently, coagulative tissue effects of circumferential irradiation of the vessel wall during balloon dilatation have been used for stabilization of acute and late results after mechanical balloon angioplasty. Enhancement of the differential light absorption of atherosclerotic plaque by use of biological dyes may further improve selective intravascular laser application. Intraoperative ECG-guided laser coagulation of arrhythmogenic areas of myocardium is a method for treatment of malignant arrhythmias. Transluminal non-operative application of myocardial laser photocoagulation has now been tested experimentally and shown to be safe and effective. There was no arrhythmogenicity or thermal damage of coronary arteries associated with this method. Innovative techniques such as nanosecond pulsed excimer lasers (athermal action) and development of "intelligent" lasers--which are equipped with spectroscopy-guided feedback systems for plaque recognition--have opened new perspectives and will further improve safety and efficacy of clinical laser application. However, according to current experience, the thermally acting Nd:YAG laser is an effective and versatile mode of laser therapy for selected cardiovascular indications.

  3. Nanotechnology combined therapy: tyrosine kinase-bound gold nanorod and laser thermal ablation produce a synergistic higher treatment response of renal cell carcinoma in a murine model.

    Science.gov (United States)

    Liu, James; Abshire, Caleb; Carry, Connor; Sholl, Andrew B; Mandava, Sree Harsha; Datta, Amrita; Ranjan, Manish; Callaghan, Cameron; Peralta, Donna V; Williams, Kristen S; Lai, Weil R; Abdel-Mageed, Asim B; Tarr, Matthew; Lee, Benjamin R

    2017-02-01

    To investigate tyrosine kinase inhibitors (TKI) and gold nanorods (AuNRs) paired with photothermal ablation in a human metastatic clear cell renal cell carcinoma (RCC) mouse model. Nanoparticles have been successful as a platform for targeted drug delivery in the treatment of urological cancers. Likewise, the use of nanoparticles in photothermal tumour ablation, although early in its development, has provided promising results. Our previous in vitro studies of nanoparticles loaded with both TKI and AuNRs and activated with photothermal ablation have shown significant synergistic cell kill greater than each individual arm alone. This study is a translation of our initial findings to an in vivo model. Immunologically naïve nude mice (athymic nude-Foxn1(nu) ) were injected subcutaneously bilaterally in both flanks (n = 36) with 2.5 × 10(6) cells of a human metastatic renal cell carcinoma cell line (RCC 786-O). Subcutaneous xenograft tumours developed into 1-cm palpable nodules. AuNRs encapsulated in human serum albumin protein (HSA) nanoparticles were synthesised with or without a TKI and injected directly into the tumour nodule. Irradiation was administered with an 808-nm light-emitting diode laser for 6 min. Mice were humanely killed 14 days after irradiation; tumours were excised, formalin fixed, paraffin embedded, and evaluated for size and the percentage of necrosis by a genitourinary pathologist. The untreated contralateral flank tumours were used as controls. In mice that did not receive irradiation, TKI alone yielded 4.2% tumour necrosis on the injected side and administration of HSA-AuNR-TKI alone yielded 11.1% necrosis. In the laser-ablation models, laser ablation alone yielded 62% necrosis and when paired with HSA-AuNR there was 63.4% necrosis. The combination of laser irradiation and HSA-AuNR-TKI had cell kill rate of 100%. In the absence of laser irradiation, TKI treatment alone or when delivered via nanoparticles produced moderate necrosis. Irradiation

  4. Optothermal profile of an ablation catheter with integrated microcoil for MR-thermometry during Nd:YAG laser interstitial thermal therapies of the liver—an in-vitro experimental and theoretical study.

    Science.gov (United States)

    Kardoulaki, Evdokia M; Syms, Richard R A; Young, Ian R; Choonee, Kaushal; Rea, Marc; Gedroyc, Wladyslaw M W

    2015-03-01

    Flexible microcoils integrated with ablation catheters can improve the temperature accuracy during local MR-thermometry in Nd:YAG laser interstitial thermal therapies. Here, the authors are concerned with obtaining a preliminary confirmation of the clinical utility of the modified catheter. They investigate whether the thin-film substrate and copper tracks of the printed coil inductor affect the symmetry of the thermal profile, and hence of the lesion produced. Transmission spectroscopy in the near infrared was performed to test for the attenuation at 1064 nm through the 25 μm thick Kapton substrate of the microcoil. The radial transmission profile of an infrared high-power, light emitting diode with >80% normalized power at 1064 nm was measured through a cross section of the modified applicator to assess the impact of the copper inductor on the optical profile. The measurements were performed in air, as well as with the applicator surrounded by two types of scattering media; crystals of NaCl and a layer of liver-mimicking gel phantom. A numerical model based on Huygens-Fresnel principle and finite element simulations, using a commercially available package (COMSOL Multiphysics), were employed to compare with the optical measurements. The impact of the modified optical profile on the thermal symmetry was assessed by examining the high resolution microcoil derived thermal maps from a Nd:YAG laser ablation performed on a liver-mimicking gel phantom. Less than 30% attenuation through the Kapton film was verified. Shadowing behind the copper tracks was observed in air and the measured radial irradiation correlated well with the diffraction pattern calculated numerically using the Huygens-Fresnel principle. Both optical experiments and simulations, demonstrate that shadowing is mitigated by the scattering properties of a turbid medium. The microcoil derived thermal maps at the end of a Nd:YAG laser ablation performed on a gel phantom in a 3 T scanner confirm that the

  5. Experimental study of thermal lensing of Nd:YAG laser

    Institute of Scientific and Technical Information of China (English)

    HU Shao-yun; ZHONG Ming; ZUO Yan; FAN Hong-ying

    2006-01-01

    A wavefront method of measuring the thermal lensing of solid-state lasers is proposed.This method is easy to implement and has a high spatial resolution for diagnosing thermal lensing.By this method,the thermal lensing of Nd:YAG laser is studied in detail.And this work provides a means for studying the thermal effects of laser medium and many instructional parameters for optimizing the design of the laser cavity.

  6. Laser ion acceleration for hadron therapy

    Science.gov (United States)

    Bulanov, S. V.; Wilkens, J. J.; Esirkepov, T. Zh; Korn, G.; Kraft, G.; Kraft, S. D.; Molls, M.; Khoroshkov, V. S.

    2014-12-01

    The paper examines the prospects of using laser plasma as a source of high-energy ions for the purpose of hadron beam therapy — an approach which is based on both theory and experimental results (ions are routinely observed to be accelerated in the interaction of high-power laser radiation with matter). Compared to therapy accelerators like synchrotrons and cyclotrons, laser technology is advantageous in that it is more compact and is simpler in delivering ions from the accelerator to the treatment room. Special target designs allow radiation therapy requirements for ion beam quality to be satisfied.

  7. Advanced Treatment Planning in Cancer Thermal Therapies

    Institute of Scientific and Technical Information of China (English)

    Theodoros SAMARAS; Esra NEUFELD; Niels KUSTER

    2016-01-01

    CEM43 thermal dose is a very common concept in thermal oncology. Thermal dose is the maximum amount of energy that can be transmitted during hyperthermia therapy conducted on temperature-sensitive tissue. Thermal dose is also the maximum value of local energy accumulation in human bodies, which can lead to tissue injury and pain. Thermal dose can also decrease the ifnishing temperature and reduce the energy to the tolerable range. There are two functions of the individualized hyperthermia treatment plan: it determines the setting and location that can realize the best tumor hyperthermia therapy; at the same time, it can decrease the effect of hyperthermia therapy on healthy tissues. There are four steps in the treatment plan of hyperthermia therapy for tumors: the ifrst step is to establish a three dimensional human body model and its corresponding an atomical structure that can be used in numerical algorithmvia medical imaging resources; the second step is to determine the volume of the electromagnetic energy accumulation. Based on the peculiarity of frequency and materials, even full-wave electromagnetic wave or quasi-static technique can be used to determine the tissue distribution. Evaluation of the therapy can be conducted based on thermal dose and the corresponding tissue damage model; the third step is to use Arrhenius model to provide direct evaluation of tissues in the thermal ablation zone, solidiifcation zone, as well as the necrotic area; the last step is the optimization of the treatment plan.

  8. Cooling Devices in Laser therapy.

    Science.gov (United States)

    Das, Anupam; Sarda, Aarti; De, Abhishek

    2016-01-01

    Cooling devices and methods are now integrated into most laser systems, with a view to protecting the epidermis, reducing pain and erythema and improving the efficacy of laser. On the basis of method employed, it can be divided into contact cooling and non-contact cooling. With respect to timing of irradiation of laser, the nomenclatures include pre-cooling, parallel cooling and post-cooling. The choice of the cooling device is dictated by the laser device, the physician's personal choice with respect to user-friendliness, comfort of the patient, the price and maintenance costs of the device. We hereby briefly review the various techniques of cooling, employed in laser practice.

  9. [History of laser in BPH therapy].

    Science.gov (United States)

    Grande, Marco; Facchini, Francesco; Moretti, Matteo; Larosa, Michelangelo; Leone, Marco; Ziglioli, Francesco; Pozzoli, Gian Luigi; Frattini, Antonio

    2014-01-01

    Laser technology has been used in the treatment of BPH for more than 15-20 years in order to challenge transurethral resection of the prostate. The aim of this review article is to analyze the evolution of laser in BPH therapy, from early coagulative techniques - progressively abandoned for their elevated postoperative morbidity and unfavorable outcomes - to the newer techniques of vaporization, resection and enucleation of the prostate. A better comprehension of tissue-laser interactions, the improvement of laser technology and a growing clinical experience have lead to the development of different laser systems (Holmium, KTP, Thulium laser) that challenge TURP. Today, HoLEP and, secondarily, PVP are the laser techniques supported by more clinical evidences and represent valid alternatives to TURP.

  10. Improving thermal barrier coatings by laser remelting.

    Science.gov (United States)

    Múnez, C J; Gómez-García, J; Sevillano, F; Poza, P; Utrilla, M V

    2011-10-01

    Thermal barrier coatings are extensively used to protect metallic components in applications where the operating conditions include aggressive environment at high temperatures. These coatings are usually processed by thermal spraying techniques and the resulting microstructure includes thin and large splats, associated with the deposition of individual droplets, with porosity between splats. This porosity reduces the oxidation and corrosion resistance favouring the entrance of aggressive species during service. To overcome this limitation, the top coat could be modified by laser glazing reducing surface roughness and sealing open porosity. ZrO2(Y2O3) top coat and NiCrAlY bond coating were air plasma sprayed onto an Inconel 600 Ni base alloy. The top coat was laser remelted and a densified ceramic layer was induced in the top surface of the ceramic coating. This layer inhibited the ingress of aggressive species and delayed bond coat oxidation.

  11. Myofascial trigger point therapy: laser therapy and dry needling.

    Science.gov (United States)

    Uemoto, Luciana; Nascimento de Azevedo, Rosany; Almeida Alfaya, Thays; Nunes Jardim Reis, Renata; Depes de Gouvêa, Cresus Vinicius; Cavalcanti Garcia, Marco Antonio

    2013-09-01

    The aim of the present review is to discuss two forms of treatment for myofascial pain: laser therapy and dry needling. Although studies have reported the deactivation of myofascial trigger points with these two methods, clinical trials demonstrating their efficacy are scarce. The literature reports greater efficacy with the use of laser over dry needling. It has been suggested that improvements in microcirculation through the administration of laser therapy may favor the supply of oxygen to the cells under conditions of hypoxia and help remove the waste products of cell metabolism, thereby breaking the vicious cycle of pain, muscle spasm and further pain. While laser therapy is the method of choice for patients with a fear of needles and healthcare professionals inexperienced with the dry needling technique, further controlled studies are still needed to prove the greater efficacy of this method.

  12. [Laser therapy of Achilles tendinitis].

    Science.gov (United States)

    Darre, E M; Klokker, M; Lund, P; Rasmussen, J D; Hansen, K; Vedtofte, P E

    1994-11-07

    The effects of low level laser treatment in soldiers with achilles tendinitis were studied in a prospective, randomized and double blind trial. Eighty-nine soldiers were enrolled in the study. Forty-six were randomized to treatment with active laser and 43 to treatment with placebo laser. No statistically significant differences in the number of consultations, morning stiffness, tenderness, crepitation, swelling, redness, VAS-score of pain and degree of unfitness for duty were found between the two treatment groups.

  13. Histopathology of human laser thermal angioplasty recanalization.

    Science.gov (United States)

    White, R A; White, G H; Vlasak, J; Fujitani, R; Kopchok, G E

    1988-01-01

    Laserprobe thermal-assisted balloon, angioplasty (LTBA) has demonstrated promising initial clinical results in recanalizing stenotic or occluded superficial femoral and popliteal arteries. Over the past year we have obtained six specimens of laserprobe thermal (LT) and LTBA treated total occlusions (avg. length 12 cm) for histopathologic examination from patients who were treated for limb salvage. Three tissue specimens were obtained acutely, and one was obtained at 6, 8, and 13 days, respectively, after laser angioplasty at the time of revision for complications or failed procedures. Serial histologic sections of the treated LT segments demonstrated recanalization of atherosclerotic lesions to approximately 60-70% of the probe diameter. The LT channels were lined by a thin layer of carbonized or coagulated tissue and several layers of cell necrosis. The histology of the thermal injury was similar regardless of whether it was produced by the heated metal cap or by free argon laser energy. Stellate balloon angioplasty fractures were frequently filled with thrombus. Analysis of these human LT and LTBA specimens revealed that the thermal device produces a confined injury through the path of least resistance. Balloon dilatation produces fragmented cracks in the vessel wall, which appear to be more thrombogenic than the carbonized LT surface. With improved guidance methods, LTBA shows potential for continuing development.

  14. Cooling devices in laser therapy

    Directory of Open Access Journals (Sweden)

    Anupam Das

    2016-01-01

    Full Text Available Cooling devices and methods are now integrated into most laser systems, with a view to protecting the epidermis, reducing pain and erythema and improving the efficacy of laser. On the basis of method employed, it can be divided into contact cooling and non-contact cooling. With respect to timing of irradiation of laser, the nomenclatures include pre-cooling, parallel cooling and post-cooling. The choice of the cooling device is dictated by the laser device, the physician′s personal choice with respect to user-friendliness, comfort of the patient, the price and maintenance costs of the device. We hereby briefly review the various techniques of cooling, employed in laser practice.

  15. Low Reactive Level Laser Therapy for Mesenchymal Stromal Cells Therapies

    Directory of Open Access Journals (Sweden)

    Toshihiro Kushibiki

    2015-01-01

    Full Text Available Low reactive level laser therapy (LLLT is mainly focused on the activation of intracellular or extracellular chromophore and the initiation of cellular signaling by using low power lasers. Over the past forty years, it was realized that the laser therapy had the potential to improve wound healing and reduce pain and inflammation. In recent years, the term LLLT has become widely recognized in the field of regenerative medicine. In this review, we will describe the mechanisms of action of LLLT at a cellular level and introduce the application to mesenchymal stem cells and mesenchymal stromal cells (MSCs therapies. Finally, our recent research results that LLLT enhanced the MSCs differentiation to osteoblast will also be described.

  16. Manipulation of heat-diffusion channel in laser thermal lithography.

    Science.gov (United States)

    Wei, Jingsong; Wang, Yang; Wu, Yiqun

    2014-12-29

    Laser thermal lithography is a good alternative method for forming small pattern feature size by taking advantage of the structural-change threshold effect of thermal lithography materials. In this work, the heat-diffusion channels of laser thermal lithography are first analyzed, and then we propose to manipulate the heat-diffusion channels by inserting thermal conduction layers in between channels. Heat-flow direction can be changed from the in-plane to the out-of-plane of the thermal lithography layer, which causes the size of the structural-change threshold region to become much smaller than the focused laser spot itself; thus, nanoscale marks can be obtained. Samples designated as "glass substrate/thermal conduction layer/thermal lithography layer (100 nm)/thermal conduction layer" are designed and prepared. Chalcogenide phase-change materials are used as thermal lithography layer, and Si is used as thermal conduction layer to manipulate heat-diffusion channels. Laser thermal lithography experiments are conducted on a home-made high-speed rotation direct laser writing setup with 488 nm laser wavelength and 0.90 numerical aperture of converging lens. The writing marks with 50-60 nm size are successfully obtained. The mark size is only about 1/13 of the focused laser spot, which is far smaller than that of the light diffraction limit spot of the direct laser writing setup. This work is useful for nanoscale fabrication and lithography by exploiting the far-field focusing light system.

  17. MR Thermometry for guidance of thermal therapy

    NARCIS (Netherlands)

    Sprinkhuizen, S.M.

    2010-01-01

    The research described in this thesis has aimed to further investigate magnetic resonance (MR) thermometry (MRT) techniques as to become a reliable guidance tool for thermal therapy. The various physical processes allowing for temperature measurements based upon the MR signal are described. It is de

  18. Therapy monitoring of laser cyclophotocoagulation

    Science.gov (United States)

    Oberheide, Uwe; Lee, Christoph; Krebs, Ronald; Welling, Herbert; Ertmer, Wolfgang; Lubatschowski, Holger

    2002-06-01

    Laser induced ultrasound provides a powerful tool for solving a major problem of laser cyclophotocoagulation, which is caused by difficulties in localization and determination of optical properties. Furthermore it adds the possibility of an online control mechanism for the process of coagulation of the ciliary body. We have developed a transducer system which is based on a fiber with 600 micrometers core diameter surrounded by a ring shaped piezoelectric PVDF detector. With this detector it is possible to localize the lateral position of the ciliary body on enucleated pigs and rabbit eyes as well as its depth. Our findings correspond well with histological sections of the measured area. Additionally, the changes in the tissue's optical properties induced by coagulation with a diode laser have been detected in real time.

  19. Photodynamic therapy with ultrafast lasers

    Science.gov (United States)

    Wachter, Eric A.; Petersen, Mark G.; Dees, Craig

    1999-06-01

    The photodynamic properties of several photosensitive compounds have been evaluated in vivo using simultaneous two-photon excitation (TPE) and multi-photon excitation (MPE). TPE and MPE are effected using a mode-locked laser, such as the mode-locked titanium:sapphire or Nd:YLF laser, the near infrared output of which allows direct promotion of various non-resonant transitions. Such lasers are exceptionally well suited for non-linear activation of exogenous or endogenous PDT agents in biological systems due to their extremely short pulse width, modest pulse energy, and high repetition rate; these features combine to effect efficient PDT activation with minimal potential for non- specific biological damage, improved spatial localization of activation, and enhanced depth of penetration. Results in several murine models are presented.

  20. Low Level Laser Therapy: laser radiation absorption in biological tissues

    Science.gov (United States)

    Di Giacomo, Paola; Orlando, Stefano; Dell'Ariccia, Marco; Brandimarte, Bruno

    2013-07-01

    In this paper we report the results of an experimental study in which we have measured the transmitted laser radiation through dead biological tissues of various animals (chicken, adult and young bovine, pig) in order to evaluate the maximum thickness through which the power density could still produce a reparative cellular effect. In our experiments we have utilized a pulsed laser IRL1 ISO model (based on an infrared diode GaAs, λ=904 nm) produced by BIOMEDICA s.r.l. commonly used in Low Level Laser Therapy. Some of the laser characteristics have been accurately studied and reported in this paper. The transmission results suggest that even with tissue thicknesses of several centimeters the power density is still sufficient to produce a cell reparative effect.

  1. All-optical thermal microscopy of laser-excited waveguides

    OpenAIRE

    He, R.; De Aldana, J.R.V.; Pedrola, G.L.; Chen, F.; JAQUE, D.

    2016-01-01

    We report on a unique combination of high-resolution confocal microscopy and ratiometric luminescence thermometry to obtain thermal images of 800 nm pumped ultrafast laser-inscribed waveguides in a Nd:YAG crystal. Thermal images evidence a strong localization of thermal load in the waveguide active volume. Comparison between experimental data and numerical simulations reveals that ultrafast laser-inscribed damage tracks in Nd:YAG crystals behave both as low-index and low-thermal conductivity ...

  2. NUMERICAL SIMULATION OF TRANSIENT THERMAL FIELD IN LASER MELTING PROCESS

    Institute of Scientific and Technical Information of China (English)

    姚国凤; 陈光南

    2004-01-01

    Numerical simulation of thermal field was studied in laser processing. The 3 -D finite element model of transient thermal calculation is given by thermal conductive equation.The effects of phase transformation latent are considered. Numerical example is given to verify the model. Finally the real example of transient thermal field is given.

  3. Thermal Performance of ATLAS Laser Thermal Control System Demonstration Unit

    Science.gov (United States)

    Ku, Jentung; Robinson, Franklin; Patel, Deepak; Ottenstein, Laura

    2013-01-01

    The second Ice, Cloud, and Land Elevation Satellite mission currently planned by National Aeronautics and Space Administration will measure global ice topography and canopy height using the Advanced Topographic Laser Altimeter System {ATLAS). The ATLAS comprises two lasers; but only one will be used at a time. Each laser will generate between 125 watts and 250 watts of heat, and each laser has its own optimal operating temperature that must be maintained within plus or minus 1 degree Centigrade accuracy by the Laser Thermal Control System (LTCS) consisting of a constant conductance heat pipe (CCHP), a loop heat pipe (LHP) and a radiator. The heat generated by the laser is acquired by the CCHP and transferred to the LHP, which delivers the heat to the radiator for ultimate rejection. The radiator can be exposed to temperatures between minus 71 degrees Centigrade and minus 93 degrees Centigrade. The two lasers can have different operating temperatures varying between plus 15 degrees Centigrade and plus 30 degrees Centigrade, and their operating temperatures are not known while the LTCS is being designed and built. Major challenges of the LTCS include: 1) A single thermal control system must maintain the ATLAS at 15 degrees Centigrade with 250 watts heat load and minus 71 degrees Centigrade radiator sink temperature, and maintain the ATLAS at plus 30 degrees Centigrade with 125 watts heat load and minus 93 degrees Centigrade radiator sink temperature. Furthermore, the LTCS must be qualification tested to maintain the ATLAS between plus 10 degrees Centigrade and plus 35 degrees Centigrade. 2) The LTCS must be shut down to ensure that the ATLAS can be maintained above its lowest desirable temperature of minus 2 degrees Centigrade during the survival mode. No software control algorithm for LTCS can be activated during survival and only thermostats can be used. 3) The radiator must be kept above minus 65 degrees Centigrade to prevent ammonia from freezing using no more

  4. Mapping and monitoring of ablative thermal therapy for improved results

    Science.gov (United States)

    Gustafson, David E.; Nadadur, Desikachari; Dalmadge, Gary W.; Nields, Morgan

    2007-02-01

    We demonstrate a method which incorporates state-of-the-art x-ray imaging with novel thermal therapy monitoring to enable improved minimally invasive thermal-therapy delivery for benign or malignant tumors. Thermal ablative techniques including RFA, microwave, and laser ablation are gaining acceptance. Incomplete treatments are common since there is no reliable method to monitor treatment zones during ablation. Treatment that doesn't encompass the entire tumor results in recurrence usually within one year. We describe a method to monitor tumor ablation zones during ablations performed under CT image guidance. This method allows the operator to predict necrosis while avoiding injury to critical structures. We validated the model using tissue and animal experiments. We also report on initial clinical results from patients receiving RFA treatments for primary or metastatic lesions. Following CT image-guidance to position RFA devices in a patient's tumor, intraprocedural CT data was acquired and processed offline. In this paper we describe the methods to monitor and provide feedback on the ablation during the study. By demonstrating the creation of accurate thermal maps in tissue and animal models, and extending this in preliminary treatment of tumors in patients, we hope to encourage the broader adoption of these methods by improving both safety and efficacy.

  5. Applied Research of Nanomaterials in Photo-thermal Therapy

    OpenAIRE

    Sun Hang; Zuo Xuejun; Liang Gang

    2015-01-01

    In the applied research of nanomaterials in photo-thermal therapy and based on the understanding of the principle of photo-thermal therapy and its medical equipment, this paper analyzes nanomaterials used for photo-thermal therapy, establishes model by the use of comprehensive evaluation method and selects nano-materials that are suiTable for photo-thermal therapy, namely, carbon nanomaterials and precious metal nano-materials. In addition, this paper analyzes the importance of human surgical...

  6. Laser puncture therapy of nervous system disorders

    Energy Technology Data Exchange (ETDEWEB)

    Anishchenko, G.; Kochetkov, V.

    1984-08-29

    The authors discuss experience with treatment of nervous system disorders by means of laser-puncture therapy. Commenting on the background of the selection of this type of treatment, they explain that once researchers determined the biological action of laser light on specific nerve receptors of the skin, development of laser apparatus capable of concentrating the beam in the millimeter band was undertaken. The devices that are being used for laser-puncture are said to operate in the red helium-neon band of light. The authors identify beam parameters that have been selected for different groups of acupuncture points of the skin, and the courses of treatment (in seconds of radiation) and their time intervals. They go on to discuss the results of treatment of over 800 patients categorized in a group with disorders of the peripheral nervous system and a second group with disorders of the central nervous system.

  7. Biodegradable magnesium nanoparticle-enhanced laser hyperthermia therapy

    Directory of Open Access Journals (Sweden)

    Wang Q

    2012-08-01

    Full Text Available Qian Wang,1 Liping Xie,1 Zhizhu He,2 Derui Di,2 Jing Liu1,21Department of Biomedical Engineering, School of Medicine, Tsinghua University, 2Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, People's Republic of ChinaBackground: Recently, nanoparticles have been demonstrated to have tremendous merit in terms of improving the treatment specificity and thermal ablation effect on tumors. However, the potential toxicity and long-term side effects caused by the introduced nanoparticles and by expelling them out of the body following surgery remain a significant challenge. Here, we propose for the first time to directly adopt magnesium nanoparticles as the heating enhancer in laser thermal ablation to avoid these problems by making full use of the perfect biodegradable properties of this specific material.Methods: To better understand the new nano “green” hyperthermia modality, we evaluated the effects of magnesium nanoparticles on the temperature transients inside the human body subject to laser interstitial heating. Further, we experimentally investigated the heating enhancement effects of magnesium nanoparticles on a group of biological samples: oil, egg white, egg yolk, in vitro pig tissues, and the in vivo hind leg of rabbit when subjected to laser irradiation.Results: Both the theoretical simulations and experimental measurements demonstrated that the target tissues injected with magnesium nanoparticles reached much higher temperatures than tissues without magnesium nanoparticles. This revealed the enhancing behavior of the new nanohyperthermia method.Conclusion: Given the unique features of magnesium nanoparticles – their complete biological safety and ability to enhance heating – which most other advanced metal nanoparticles do not possess, the use of magnesium nanoparticles in hyperthermia therapy offers an important “green” nanomedicine modality for treating tumors

  8. 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.

  9. Laser-enhanced thermal effect of moderate intensity focused ultrasound on bio-tissues

    Science.gov (United States)

    Zhao, JinYu; Zhang, ShuYi; Shui, XiuJi; Fan, Li

    2017-09-01

    For avoiding extra-damage to healthy tissues surrounding the focal point during high intensity focused ultrasound (HIFU) treatment in medical therapy, to reduce the ultrasonic intensity outside the focal point is expected. Thus, the heating processes induced by moderate intensity focused ultrasound (MIFU) and enhanced by combined irradiation of laser pulses for bio-tissues are studied in details. For fresh bio-tissues, the enhanced thermal effects by pulsed laser combined with MIFU irradiation are observed experimentally. To explore the mechanisms of these effects, several tissue-mimicking materials composed of agar mixed with graphite powders are prepared and studied for comparison, but the laser-enhanced thermal effects in these mimicking materials are much less than that in the fresh bio-tissues. Therefore, it is suggested that the laser-enhanced thermal effects may be mainly attributed to bio-activities and related photo-bio-chemical effects of fresh tissues.

  10. Laser pulse heating of surfaces and thermal stress analysis

    CERN Document Server

    Yilbas, Bekir S; Al-Aqeeli, Nasser; Al-Qahtani, Hussain M

    2013-01-01

    This book introduces laser pulse heating and thermal stress analysis in materials surface. Analytical temperature treatments and stress developed in the surface region are also explored. The book will help the reader analyze the laser induced stress in the irradiated region and presents solutions for the stress field. Detailed thermal stress analysis in different laser pulse heating situations and different boundary conditions are also presented. Written for surface engineers.

  11. A new diode laser acupuncture therapy apparatus

    Science.gov (United States)

    Li, Chengwei; Huang, Zhen; Li, Dongyu; Zhang, Xiaoyuan

    2006-06-01

    Since the first laser-needles acupuncture apparatus was introduced in therapy, this kind of apparatus has been well used in laser biomedicine as its non-invasive, pain- free, non-bacterium, and safetool. The laser acupuncture apparatus in this paper is based on single-chip microcomputer and associated by semiconductor laser technology. The function like traditional moxibustion including reinforcing and reducing is implemented by applying chaos method to control the duty cycle of moxibustion signal, and the traditional lifting and thrusting of acupuncture is implemented by changing power output of the diode laser. The radiator element of diode laser is made and the drive circuit is designed. And chaos mathematic model is used to produce deterministic class stochastic signal to avoid the body adaptability. This function covers the shortages of continuous irradiation or that of simple disciplinary stimulate signal, which is controlled by some simple electronic circuit and become easily adjusted by human body. The realization of reinforcing and reducing of moxibustion is technological innovation in traditional acupuncture coming true in engineering.

  12. Laser therapy in treatment of generalized parodontitis.

    Science.gov (United States)

    Mdinaradze, N

    2006-05-01

    Laser therapy has a significant place among the treatment methods in stomatology. An experiment was carried out on 48 male white rats with the masses of 150,0-200,0 gr. Parodontitis was simulated by application of ligature around the dental cervix. Morphometric indicators such as diameter of arterioles and capillars Dk (mkm), density of blood vessels distribution VvK, diameter of the zone of peri-capillar diffusion Di (mkm) and intensity of the local blood circulation were taken as the criteria for the effectiveness of treatment. We also conducted microbiological studies of the mucous tunic of the oral cavity. The results gained on the seventh day of treatment equaled to the reference ones. As a result of a combined treatment with medications (3% indometacin ointment, heparin ointment, vitamins, ferments, antibiotics) and laser-beam therapy, the diameter of arterioles and capillaries was increased, or it is to say, the diameter indicator equaled to the reference one, the capillary distribution density V(v)(K) was increased and the diameter of peri-capillar diffusion was also increased. The indicator of the local blood circulation was increased and reached the norm. The analysis of the data gained through research indicates the effeciency of inclusion of laser therapy into the thorough treatment of parodontitis.

  13. Noninvasive thermal coagulation of deep subsurface tissue structures using a laser probe with integrated contact cooling.

    Science.gov (United States)

    Cilip, Christopher M; Scott, Nicholas J; Trammell, Susan R; Fried, Nathaniel M

    2008-01-01

    Cooling methods are used during cosmetic laser surgery to preserve a superficial layer of the skin surface. This study investigates contact cooling for sparing a deeper layer of the tissue surface during laser irradiation of subsurface tissues, with the goal of developing noninvasive laser therapy applications beyond cosmetic surgery. A laser probe was designed and tested for simultaneous laser irradiation and contact cooling of liver tissue, ex vivo. Gross and histologic examination was used to quantify thermal lesion dimensions. Liver lesions of 5.8-mm-diameter were created, while preserving the tissue surface to a depth of 1.5 mm. In vivo animal studies are planned to optimize the laser and cooling parameters for potential clinical applications.

  14. Laser X-ray Conversion and Electron Thermal Conductivity*

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The influence of electron thermal conductivity on the laser x-ray conversion in the coupling of 3ωo laser with Au plane target has been investigated by using a non-LTE radiation hydrodynamic code. The non-local electron thermal conductivity is introduced and compared with the other two kinds of the flux-limited Spitzer-Harm description. The results show that the non-local thermal conductivity causes the increase of the laser x-ray conversion efficiency andimportant changes of the plasma state and coupling feature

  15. Subvisible retinal laser therapy: titration algorithm and tissue response.

    Science.gov (United States)

    Lavinsky, Daniel; Sramek, Christopher; Wang, Jenny; Huie, Philip; Dalal, Roopa; Mandel, Yossi; Palanker, Daniel

    2014-01-01

    Laser therapy for diabetic macular edema and other retinal diseases has been used within a wide range of laser settings: from intense burns to nondamaging exposures. However, there has been no algorithm for laser dosimetry that could determine laser parameters yielding a predictable extent of tissue damage. This multimodal imaging and structural correlation study aimed to verify and calibrate a computational model-based titration algorithm for predictable laser dosimetry ranging from nondamaging to intense coagulative tissue effects. Endpoint Management, an algorithm based on a computational model of retinal photothermal damage, was used to set laser parameters for various levels of tissue effect. The algorithm adjusts both power and pulse duration to vary the expected level of thermal damage at different percentages of a reference titration energy dose. Experimental verification was conducted in Dutch Belted rabbits using a PASCAL Streamline 577 laser system. Titration was performed by adjusting laser power to produce a barely visible lesion at 20 ms pulse duration, which is defined as the nominal (100%) energy level. Tissue effects were then determined for energy levels of 170, 120, 100, 75, 50, and 30% of the nominal energy at 1 hour and 3, 7, 30, and 60 days after treatment. In vivo imaging included fundus autofluorescence, fluorescein angiography, and spectral-domain optical coherence tomography. Morphologic changes in tissue were analyzed using light microscopy, as well as scanning and transmission electron microscopy. One hundred and seventy percent and 120% levels corresponded to moderate and light burns, respectively, with damage to retinal pigment epithelium, photoreceptors, and at highest settings, to the inner retina. 50% to 75% lesions were typically subvisible ophthalmoscopically but detectable with fluorescein angiography and optical coherence tomography. Histology in these lesions demonstrated some selective damage to retinal pigment epithelium and

  16. Intralesional laser therapy for vascular malformations.

    Science.gov (United States)

    Ma, Linda W; Levi, Benjamin; Oppenheimer, Adam J; Kasten, Steven J

    2014-11-01

    Intralesional laser therapy for the treatment of vascular malformations (VMs) has been previously reported for select patient populations. Larger studies, over a wider variety of indications, are needed to better define the potential role of this technology. In the current study, a 12-year, retrospective review of 44 patients who underwent 73 intralesional Nd:YAG or diode laser treatments of VMs was performed. The most commonly encountered lesions were venous malformations (66%) and the most commonly involved anatomic locations were the head and neck regions (41%) and lower extremity (39%). Primary indications for treatment were enlargement (73%) and pain (52%). Lesion size was reduced in 94% of cases after treatment and pain was improved in 91% of cases. Minor postoperative complications occurred in 16 (36%) patients. There was no difference in treatment response among various VM subtypes or anatomic locations (P=0.497, P=0.866) or in the incidence of complications (P=0.531, P=0.348). Age was the only factor associated with an increased risk of complications (odds ratio, 1.034; P=0.038). When used in accordance with the suggested guidelines, intralesional laser therapy is a safe and effective treatment modality for VMs of varying compositions and locations.

  17. Immunodeficiency and laser magnetic therapy in urology

    Science.gov (United States)

    Maati, Moufagued; Rozanov, Vladimir V.; Avdoshin, V. P.

    1996-11-01

    The importance of immunodeficiency problem has increased last time not only due to AIDS appearance, but also to a great extent as a result of the development and active practical use of the methods of immunology parameters investigations. Al great pharmaceutical firms are organizing the process of creating the drugs, influencing on the different phases of immunity, but unfortunately, the problem of their adverse effect and connected complications is till today a milestone. A great number of investigations, proving a good effect of laser-magnetic therapy concerning immune system have been done today. There is, in particular, changing of blood counts and immunologic tests after intravenous laser irradiation of blood. Intravenous laser irradiation of blood results in increasing of lymphocytes, T-immuno stimulation, stabilization of t-lymphocyte subpopulation, increasing of t-lymphocyte helper activity and decreasing of suppressor one.Under this laser action number of circulating immune complexes is decreased, and blood serum bactericide activity and lisozyme number are increased.

  18. Analysis of Thermal Effects in Laser Rod Pumped by Repetitively Pulsed Laser Diode Array

    Institute of Scientific and Technical Information of China (English)

    DAI Qin; LI Xin-zhong; WU Ri-na; WANG Xi-jun

    2007-01-01

    Based on some assumptions, the numerical model of thermal distribution in solid state laser crystal pumped by pulsed laser diode is set up due to the pumped intensity distribution. Taking into account the property of YAG materials that varies with temperature, the transient temperature distribution of the laser crystal is calculated using finite element method on condition that K is a constant and a function of temperature. Then, the influence of the pumping parameters on the thermal effect in laser crystal is also discussed. This study is helpful to optimize the design of the diode side pumped solid state lasers.

  19. Comedones induced by vascular laser therapy

    Directory of Open Access Journals (Sweden)

    Gulsen Tukenmez Demirci

    2016-01-01

    Full Text Available A 21-year-old female presented with acne-like blackheads on brownish areas located on the cheek. She had been treated with neodymium-doped yttrium aluminium garnet (Nd-YAG laser (1071 nm, 160 j/cm 2 , three months ago for erythema and telangiectasia of her face. Afterwards, she developed atrophic, slightly depressed, hyperpigmented, 3-4 mm scars with superimposed tiny comedones within the treated areas. Topical treatment with tretinoin 0.05% cream on alternate days, and Sun Protection Factor (SPF 50 sunscreen daily were commenced. After 2 months, comedones and hyperpigmentation mostly resolved but mild superficial atrophy persisted. According to our knowledge, this is the first case of atrophic scars studded with open comedones, developing shortly after laser therapy used for facial telangiectasia.

  20. Thermal analysis of line-defect photonic crystal lasers

    DEFF Research Database (Denmark)

    Xue, Weiqi; Ottaviano, Luisa; Chen, Yaohui

    2015-01-01

    We report a systematic study of thermal effects in photonic crystal membrane lasers based on line-defect cavities. Two material platforms, InGaAsP and InP, are investigated experimentally and numerically. Lasers with quantum dot layers embedded in an InP membrane exhibit lasing at room temperatur...

  1. Laser therapy in general dental practice

    Science.gov (United States)

    Darbar, Arun A.

    2006-02-01

    This is a clinical presentation on the use of laser therapy in a private dental practice using a 810nm diode. A wide range of conditions involving pain management, treatment and as an adjunct to procedures to enhance patient comfort and experience. This will include cases treated for TMD (Temporo mandibular dysfunction), apthous ulcers, angular chelitis, cold sores, gingival retraction, periodontal treatment and management of failing dental implants. The case presentation will include the protocols used and some long term reviews. The results have been very positive and will be shared to enable this form of treatment to be used more frequently and with confidence within dental practice.

  2. Current and long-term technologies of laser therapy

    Science.gov (United States)

    Ulashcyk, Vladimir S.; Volotovskaya, Anna V.

    2007-06-01

    Laser therapy, using low-energy laser radiation, is being more and more applied. The most applied technology is transcutaneous radiation of tissues by laser radiation. Originally, a direct action on a pathological site was mostly used, but recently more attention is given to reflexogenic areas, acupuncture points, and endocrine organ projection sites. The development of light-conductive engineering made it possible to practically apply intraorgan laser therapy. This technology is widely spread in gynecology, otorhinolaryngology, urology, gastroenterology, etc. Close to it are different versions of intratissue laser therapy (intraosteal, periosteal, myofascial). A special kind of laser therapy is laser hemotherapy. Depending on the techniques and protocol of its application, there are extracorporeal, intravascular, and supravenous ways of action. According to our comparative investigations, supravenous hemotherapy by its therapeutic efficacy and major medicinal effects can be well compared with intravascular laser hemotherapy. With good prospects and efficiency is laser therapy as a combination of laser and other physical factors. Magnetolaser therapy has been scientifically substantiated and practically applied so far. Theoretically and experimentally substantiated is a combined application of laser radiation and physical factors such as ultrasound, direct current field, vacuum, cryotherapy, etc. Experimental research and few so far clinical observations are indicative of prospects of a complex application of laser radiation and drugs. To improve light absorption, laser radiation is combined with different dyes. Photodynamic therapy, originally used in oncology, is applied today in treating different diseases. We showed a possibility of using a number of drugs possessing simultaneously photosensitizing properties to this end. Laser radiation significantly influences pharmacokinetics and pharmacodynamics of drugs, which gives reason to practically implement laser

  3. ICG laser therapy of acne vulgaris

    Science.gov (United States)

    Tuchin, Valery V.; Altshuler, Gregory B.; Genina, Elina A.; Bashkatov, Alexey N.; Simonenko, Georgy V.; Odoevskaya, Olga D.; Yaroslavsky, Ilya V.

    2004-07-01

    The near-infrared (NIR) laser radiation due to its high penetration depth is widely used in phototherapy. In application to skin appendages a high selectivity of laser treatment is needed to prevent light action on surrounding tissues. Indocyanine Green (ICG) dye may provide a high selectivity of treatment due to effective ICG uploading by a target and its narrow band of considerable absorption just at the wavelength of the NIR diode laser. The goal of this study is to demonstrate the efficacy of the NIR diode laser phototherapy in combination with topical application of ICG suggested for soft and thermal treatment of acne vulgaris. 28 volunteers with facile or back-located acne were enrolled. Skin sites of subjects were stained by ICG and irradiated by NIR laser-diode light (803 or 809 nm). Untreated, only stained and only light irradiated skin areas served as controls. For soft acne treatment, the low-intensity (803 nm, 10 - 50 mW/cm2, 5-10 min) or the medium-intensity (809 nm, 150 - 190 mW/cm2, 15 min) protocols were used. The single and multiple (up to 8-9) treatments were provided. The individual acne lesions were photothermally treated at 18 W/cm2 (803 nm, 0.5 sec) without skin surface cooling or at 200 W/cm2 (809 nm, 0.5 sec) with cooling. The results of the observations during 1-2 months after the completion of the treatment have shown that only in the case of the multiple-wise treatment a combined action of ICG and NIR irradiation reduces inflammation and improves skin state during a month without any side effects. At high power densities (up to 200 W/cm2) ICG stained acne inflammatory elements were destructed for light exposures of 0.5 sec. Based on the concept that hair follicle, especially sebaceous gland, can be intensively and selectively stained by ICG due to dye diffusion through pilosebaceous canal and its fast uptake by living microorganisms, by vital keratinocytes of epithelium of the canal and sebaceous duct, and by rapidly proliferating

  4. Prompt pre-thermal laser ion sheath acceleration with ultra-short laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Zeil, Karl; Bussmann, Michael; Cowan, Thomas; Kluge, Thomas; Kraft, Stephan; Metzkes, Josefine; Schramm, Ulrich [Helmholtz-Zentrum Dresden-Rossendorf (Germany)

    2013-07-01

    Recent laser-ion acceleration experiments performed at the 150 TW Draco laser in Dresden, Germany, have demonstrated the importance of a precise understanding of the electron dynamics in solids on an ultra-short time scale. For example, with ultra-short laser pulses a description based purely on the evolution of a thermal electron ensemble, as in standard TNSA models, is not sufficient anymore. Rather, non-thermal effects during the ultra-short intra-pulse phase of laser-electron interaction in solids become important for the acceleration of ions when the laser pulse duration is in the order of only a few tens of femtoseconds. While the established maximum ion energy scaling in the TNSA regime goes with the square root of the laser intensity, for such ultra short pulse durations the maximum ion energy is found to scale linear with laser intensity, motivating the interest in such laser systems. Investigating the influence of laser pulse contrast, laser polarization and laser incidence angle on the proton maximum energy and angular distribution, we present recent advances in the description of the laser interaction with solids, focusing on the implications of intra-pulse non-thermal phenomena on the ion acceleration.

  5. Thermal design and flight validation for laser communicator equipment

    Science.gov (United States)

    Meng, Henghui; Geng, Liyin; Tan, Canghai; Li, Guoqiang

    2014-11-01

    Laser communicator equipment, designed for advanced optical communication, with a large capacity communication, good encryption and lightweight structures, etc., has a wide range of applications. As for the special transmission characteristic of optical communication, laser phase in the transmission path should be accurate, and less thermal deformation for the optical parts is required in the working process, so the laser communicator equipment has a high level requirement for temperature. Large power units cooling, outer two-dimensional rotating units, temperature control for rotating cable, and high temperature stability and equality, bring a challenge for thermal design. Using structure -electric-thermo-optical integration technology, active and passive thermal control methods are adopt in thermal design for laser communicator equipment: heat-conducted plate and heat pipe were adopted for heat transfer of high heat-flux parts, a new passive and active thermal control method to solve cable cryogenic problems, and high precision temperature control methods were applied for key parts. In-orbit data were analyzed, and the results prove the thermal design correct, and bring a way to thermal control for the equipment with high heat flux and running parts.

  6. Improvement of disfiguring skin conditions by laser therapy

    NARCIS (Netherlands)

    van Drooge, A.M.

    2014-01-01

    Since their introduction in dermatology, lasers became a welcome addition to the therapeutic armentarium for disfiguring skin conditions. In this thesis, we evaluated laser therapy for the treatment of scars, of benign dermal tumours, and of port-wine stains. For scars, many different laser devices

  7. Improvement of disfiguring skin conditions by laser therapy

    NARCIS (Netherlands)

    van Drooge, A.M.

    2014-01-01

    Since their introduction in dermatology, lasers became a welcome addition to the therapeutic armentarium for disfiguring skin conditions. In this thesis, we evaluated laser therapy for the treatment of scars, of benign dermal tumours, and of port-wine stains. For scars, many different laser devices

  8. Laser therapy applying the differential approaches and biophotometrical elements

    Science.gov (United States)

    Mamedova, F. M.; Akbarova, Ju. A.; Umarova, D. A.; Yudin, G. A.

    1995-04-01

    The aim of the present paper is the presentation of biophotometrical data obtained from various anatomic-topographical mouth areas to be used for the development of differential approaches to laser therapy in dentistry. Biophotometrical measurements were carried out using a portative biophotometer, as a portion of a multifunctional equipping system of laser therapy, acupuncture and biophotometry referred to as 'Aura-laser'. The results of biophotometrical measurements allow the implementation of differential approaches to laser therapy of parodontitis and mucous mouth tissue taking their clinic form and rate of disease into account.

  9. Applied Research of Nanomaterials in Photo-thermal Therapy

    Directory of Open Access Journals (Sweden)

    Sun Hang

    2015-01-01

    Full Text Available In the applied research of nanomaterials in photo-thermal therapy and based on the understanding of the principle of photo-thermal therapy and its medical equipment, this paper analyzes nanomaterials used for photo-thermal therapy, establishes model by the use of comprehensive evaluation method and selects nano-materials that are suiTable for photo-thermal therapy, namely, carbon nanomaterials and precious metal nano-materials. In addition, this paper analyzes the importance of human surgical health by the use of photo-thermal therapy and gives considerations from three aspects, that is, the surgical equipment health, the operating room hygiene and the medical health. This paper also establishes a mathematical model through correlation analysis and credibility analysis, thus emphasizing the necessity of surgical health.

  10. Current status of clinical laser applications in periodontal therapy.

    Science.gov (United States)

    Aoki, Akira; Mizutani, Koji; Takasaki, Aristeo Atsushi; Sasaki, Katia Miyuki; Nagai, Shigeyuki; Schwarz, Frank; Yoshida, Itaru; Eguro, Toru; Zeredo, Jorge Luis; Izumi, Yuichi

    2008-01-01

    Periodontal disease is a chronic inflammatory disorder caused by bacterial infection. Laser treatment demonstrates specific characteristics that may be valuable in managing periodontal disease. In addition, lasers reduce stress and uncomfortable conditions for patients during and after treatment compared to other conventional tools. This article reviews the literature to describe the current clinical applications of lasers for gingival tissue management-including esthetic treatment, non-surgical and surgical periodontal pocket therapy, osseous surgery, and implant therapy.

  11. Melanoma diagnosed in lesions previously treated by laser therapy.

    Science.gov (United States)

    Delker, Sarah; Livingstone, Elisabeth; Schimming, Tobias; Schadendorf, Dirk; Griewank, Klaus G

    2017-01-01

    Laser therapy has become a routine procedure in dermatological practice and is frequently also used for pigmented lesions. Few reports exist of melanomas diagnosed in lesions previously treated by laser therapy. Between 2007 and 2014, we identified 11 patients who presented to our department with a melanoma diagnosed in a region previously treated by laser therapy. The course of events until the diagnosis of melanoma was assessed as well as patient outcome including treatment for disease progression. No histological assessment had been performed prior to laser therapy in nine of 11 (82%) cases. Benign melanocytic lesions had been diagnosed by biopsy prior to laser therapy in the other two cases. Time from laser therapy to diagnosis of melanoma ranged from less than 1 to 10 years. Stage of disease at diagnosis varied from stage IA to IIIC. Four patients progressed to stage IV disease, of whom at least one died of melanoma. We conclude that laser treatment of pigmented lesions can complicate the diagnosis of melanoma and lead to diagnosis delay with potentially fatal consequences. Considering this risk, we believe laser therapy for pigmented lesions should either be avoided entirely or at a minimum performed only after prior histological assessment. © 2016 Japanese Dermatological Association.

  12. Laser therapy in post herpetic neuralgia

    Directory of Open Access Journals (Sweden)

    Mittal R

    1996-01-01

    Full Text Available Combi laser therapy was evaluated in 50 cases of established post herpetic neuralgia (PHN. Established PHN term was used when neuralgia persisted after 3 months of disappearance of herpes zoster (HZ vesicles. Twenty exposures were given and affected areas were irradiated from a distance of 2 cm at a frequency of 5000 Hz each area being exposed for a period of 1.23 minutes ie, 8J/cm2 of beam was given. Therapeutic evaluation was done on 4th, 8th, 12th, 16th, and 20th day. All 17 cases of established PHN of duration upto 3 months healed after 16 exposures and in the end 44/50 had cure, 5/50 had partial relief and one patient left trial after 2nd exposure.

  13. Optical-Thermal Response of Laser-Irradiated Tissue

    CERN Document Server

    Welch, Ashley J

    2011-01-01

    The second edition of 'Optical-Thermal Response of Laser-Irradiated Tissue' maintains the standard of excellence established in the first edition, while adjusting the content to reflect changes in tissue optics and medical applications since 1995. The material concerning light propagation now contains new chapters devoted to electromagnetic theory for coherent light. The material concerning thermal laser-tissue interactions contains a new chapter on pulse ablation of tissue. The medical applications section now includes several new chapters on Optical Coherent Tomography, acoustic imaging, molecular imaging, forensic optics and nerve stimulation. A detailed overview is provided of the optical and thermal response of tissue to laser irradiation along with diagnostic and therapeutic examples including fiber optics. Sufficient theory is included in the book so that it is suitable for a one or two semester graduate or for senior elective courses. Material covered includes: 1. light propagation and diagnostic appl...

  14. Selective vascular injury during cutaneous laser therapy

    Science.gov (United States)

    Tunnell, James William

    Pulsed laser irradiation in conjunction with cryogen spray cooling (CSC) can induce selective vascular injury to remove cutaneous hypervascular malformations such as port wine stains (PWS), hemangiomas, and facial veins. In this group of studies, we characterized the cryogen heat removal process and determined the effects of pulsed laser irradiation in conjunction with cryogen spray cooling of human skin. First, we employed an inverse heat conduction algorithm to measure the thermal boundary condition due to CSC in in vitro skin phantoms. Second, we developed a mathematical model of laser irradiation in conjunction with CSC in human skin. We determined tissue damage and temperature profiles due to varying combinations of laser pulse duration, radiant exposure, and CSC application times. Finally, we used ex vivo and in vivo human skin to determine the effects of high radiant exposures and CSC on epidermal and vascular injury. CSC induces a dynamic cooling effect, removing heat from the skin both during and following the spurt application time. Residual cryogen, deposited on the skin surface during the cryogen spurt, remains on the skin surface several times as long as the as cryogen spurt itself. The heat removal rate during the cryogen spurt is greatest; however, the total energy removed following the cryogen spurt is also substantial (approximately half as much as during the spurt application time). CSC was effective in protecting the human skin epidermis in light to moderately pigmented skin. Mathematical modeling, ex vivo, and in vivo studies showed that the epidermal damage threshold could be increased by a factor of approximately two. Increased radiant exposures increased the risk of non-selective vascular injury observed in histology as injury to the epidermis and perivascular collagen; however, proper choice of cryogen cooling durations resulted in the elimination of epidermal injury as well as perivascular tissue injury. In addition, higher radiant

  15. Thermal Processes Using Attosecond Laser Pulses When Time Matters

    CERN Document Server

    Kozłowski, Mirosław

    2006-01-01

    This book contains a study of the thermal processes initiated by attosecond laser pulses. Considering the existence of the experimental evidence for the trains of the attosecond laser pulses, we developed the theoretical framework for attophysics, i.e. physics of phenomena with time duration in the attosecond domain. This time domain is concerned with phenomena whose duration is much shorter than the relaxation time for atomic, molecular and nanoparticles scales.

  16. Loss of vasoreactivity by laser thermal energy or argon laser irradiation.

    Science.gov (United States)

    Tomaru, T; Uchida, Y; Nakamura, F; Miwa, A Y; Kawai, S; Okada, R; Sugimoto, T

    1993-05-01

    Vasoreactivity of laser-treated vessels was investigated in two different experimental conditions. The canine left circumflex coronary artery (LCx) was lased under perfusion with Krebs-bicarbonate buffer by means of a thermal laser (hot-tip probe, HT) at 7 W for 6 seconds and an argon laser beam through a 300 microns optical fiber at 3 W (tip power) for 1 second at 12 spots. A nontreated segment of the LCx served as a control. Two 3-mm long segments were obtained from the treated segment: one to measure the results of potassium (K) induced contraction, and another 3, 4 diaminopyridine (DAP; K channel inhibitor) induced contraction. In 11 instances, coronary angiography of the perfused artery showed less than 50% stenosis after laser treatment. The segments were then mounted isometrically with 1 g tension in Krebs-bicarbonate buffer. Contraction was induced either with 30 mM KCI or 10(-2) M DAP and expressed as developed tension (gram; g). KCI induced vasocontraction of 4.15 +/- 0.93 g in the control, 0.33 +/- 0.71 g in laser irradiated segments (P thermally-treated segments (P thermally treated segments (P dilatation reduced the stenosis to less than 50%. The lesions also showed reduced vasoreactivity. In vivo thermal angioplasty resulted in reduced vasoreactivity compared to control in 4 anesthetized dogs. Thus, laser and thermal angioplasty reduced vasoreactivity induced by either KCI or 3, 4 DAP. Neither acetylcholine at 10(-6) M nor papaverine at 10(-4) M was able to induce relaxation of treated segments. In conclusion, 1) the lased coronary artery loses its vasoreactivity to either a constrictive or relaxing agent, 2) although stenosis may be produced by laser energy, additional balloon dilatation can reduce residual stenosis, and 3) laser thermal or argon laser angioplasty may prevent severe coronary spasm.

  17. Laser Remelting of Plasma Sprayed Thermal Barrier Coatings

    Institute of Scientific and Technical Information of China (English)

    Gang ZHANG; Yong LIANG; Yingna WU; Zhongchao FENG; Bingchun ZHANG; Fangjun LIU

    2001-01-01

    A CO2 continuous wave laser with defocused beam was used for remelting the surface of plasma sprayed ZrO2-8 wt pct Y2O3 (8YSZ)/Ni22Cr10AlY thermal barrier coatings (TBCs) on GH536 superalloy substrate. Two main laser processing parameters, power and travel speed, were adopted to produce a completely remelted layer, and their effects on remelted appearance,remelting depth, density and diameter of depression, space of segment crack and remelted microstructure were evaluated. With energy of 4.0 to 8.0 J.mm-2, an appropriate laser processing for applicable remelted layer was suggested.

  18. LASER DEPOSITION. THE AREA THERMAL FIELD

    Directory of Open Access Journals (Sweden)

    Florin CIOFU

    2016-05-01

    Full Text Available By laser direct deposition, the parts are manufactured by injecting powder in a melt metal bath with the help of the laser. During the manufacture it is deployed a complex “ thermic history” in the different built regions. This includes re-melting and many thermic cycles at low temperatures (of hundreds of degrees. The phenomena of thermic transmission are variable in time, being by excellence reversible phenomena, too, as the temperature difference which intervenes cannot be ever small infinite. In the most general case, the temperature is a function of space coordinates, and of the time ح

  19. Rapid scanning thermal lens/laser transmission densitometer.

    Science.gov (United States)

    Peck, K; Demana, T; Morris, M D

    1988-01-01

    An automated densitometer based on the thermal lens principle is described. The apparatus also operates as a conventional laser transmission densitometer. Comparison of the performance in both modes shows that thermal lens densitometry provides lower detection limits, but that transmission densitometry is more satisfactory at high optical densities. The instrument is characterized with proteins separated by SDS-PAGE and stained with Coomassie Brilliant Blue G250.

  20. [The laser therapy and laser acupunture of patients with chronic recurrent aphthous stomatitis].

    Science.gov (United States)

    Mikhaĭlova, R I; Terekhova, N V; Zemskaia, E A; Melkadze, N

    1992-01-01

    Laser therapy and laser acupuncture of the biologically active sites were administered to 24 patients with chronic recurrent aphthous stomatitis. The biologically active sites were selected individually with due consideration for the underlying somatic condition. Good results were achieved in the patients with the fibrous form of chronic aphthous stomatitis. Secretory and serum immunoglobulin levels were monitored over the course of laser treatment.

  1. Fetal laser therapy: applications in the management of fetal pathologies.

    Science.gov (United States)

    Mathis, Jérôme; Raio, Luigi; Baud, David

    2015-07-01

    Fetoscopic coagulation of placental anastomoses is the treatment of choice for severe twin-to-twin transfusion syndrome. In the present day, fetal laser therapy is also used to treat amniotic bands, chorioangiomas, sacrococcygeal teratomas, lower urinary tract obstructions and chest masses, all of which will be reviewed in this article. Amniotic band syndrome can cause limb amputation by impairing downstream blood flow. Large chorioangiomas (>4 cm), sacrococcygeal teratomas or fetal hyperechoic lung lesions can lead to fetal compromise and hydrops by vascular steal phenomenon or compression. Renal damage, bladder dysfunction and lastly death because of pulmonary hypolasia may be the result of megacystis caused by a posterior urethral valve. The prognosis of these pathologies can be dismal, and therapy options are limited, which has brought fetal laser therapy to the forefront. Management options discussed here are laser release of amniotic bands, laser coagulation of the placental or fetal tumor feeding vessels and laser therapy by fetal cystoscopy. This review, largely based on case reports, does not intend to provide a level of evidence supporting laser therapy over other treatment options. Centralized evaluation by specialists using strict selection criteria and long-term follow-up of these rare cases are now needed to prove the value of endoscopic or ultrasound-guided laser therapy.

  2. Laser thermal probe recanalization of occluded arteries.

    Science.gov (United States)

    White, R A; White, G H

    1989-04-01

    Applications of laser energy for treatment of vascular disease have recently received much attention; metal-tipped laser probes are being investigated as a device for recanalization of occluded arteries, especially as an adjunct to balloon dilatation. Developments in instrumentation and techniques have reduced the incidence of complications, notably perforation, to an acceptable level. Initial data show that recanalization of iliac, femoral, and popliteal lesions can be accomplished in a majority of cases, with the chance of success being inversely proportional to the length of occlusion. Results in the tibial vessels are disappointing. Patency of the treated vessels at 12 months appears to be superior to that of percutaneous transluminal angioplasty for similar lesions but inferior to that of surgical bypass for all occlusions greater than 3 cm in length.

  3. Laser Therapy For Arteriosclerosis: Current Review

    Science.gov (United States)

    Dries, David J.; Pollock, Marc E.; Eugene, John

    1987-03-01

    Shortly after the ruby laser was introduced, in 1959, a study for the use of this ruby laser for the in-vitro dissolution of arteriosclerotic plaque was performed.' With subsequent advances in laser technology and with refined delivery techniques, laser applications to the treatment of arteriosclerosis in the coronary arteries and peripheral vascular system is a reality. This report reviews the disease process, arteriosclerosis, and the ef-forts towards laser treatment of this disease. We conclude with a review of the technical barriers to the routine application of laser energy in arteriosclerotic cardiovascular disease and the progress being made to overcome these obstacles.

  4. Laser-induced thermal desorption of aniline from silica surfaces

    Science.gov (United States)

    Voumard, Pierre; Zenobi, Renato

    1995-10-01

    A complete study on the energy partitioning upon laser-induced thermal desorption of aniline from silica surfaces was undertaken. The measurements include characterization of the aniline-quartz adsorption system using temperature-programmed desorption, the extrapolation of quasiequilibrium desorption temperatures to the regime of laser heating rates on the order of 109-1010 K/s by computational means, measurement of the kinetic energy distributions of desorbing aniline using a pump-probe method, and the determination of internal energies with resonance-enhanced multiphoton ionization spectroscopy. The measurements are compared to calculations of the surface temperature rise and the resulting desorption rates, based on a finite-difference mathematical description of pulsed laser heating. While the surface temperature of laser-heated silica reaches about 600-700 K at the time of desorption, the translational temperature of laser-desorbed aniline was measured to be Tkin=420±60 K, Tvib was 360±60 K, and Trot was 350±100 K. These results are discussed using different models for laser-induced thermal desorption from surfaces.

  5. A review of laser and light therapy in melasma.

    Science.gov (United States)

    Trivedi, M K; Yang, F C; Cho, B K

    2017-03-01

    Melasma is a dysregulation of the homeostatic mechanisms that control skin pigmentation and excess pigment is produced. Traditional treatment approaches with topical medications and chemical peels are commonly used but due to the refractory and recurrent nature of melasma, patients often seek alternative treatment strategies such as laser and light therapy. Several types of laser and light therapy have been studied in the treatment of melasma. Intense pulsed light, low fluence Q-switched lasers, and non-ablative fractionated lasers are the most common lasers and light treatments that are currently performed. They all appear effective but there is a high level of recurrence with time and some techniques are associated with an increased risk for postinflammatory hyper- or hypopigmentation. The number and frequency of treatments varies by device type but overall, Q-switched lasers require the greatest number of treatment applications to see a benefit. Vascular-specific lasers do not appear to be effective for the treatment of melasma. Ablative fractionated lasers should be used with caution because they have a very high risk for postinflammatory hypo- and hyperpigmentation. The use of nonablative fractionated laser treatments compared with other laser and light options may result in slightly longer remission intervals. Picosecond lasers, fractional radiofrequency, and laser-assisted drug delivery are promising future approaches to treat melasma. The goal of this review is to summarize the efficacy and safety of the most commonly used laser and light therapies to treat melasma, briefly present future laser-based treatment options for patients with melasma, and provide recommendations for treatment on the basis of the reviewed information.

  6. A review of laser and light therapy in melasma

    Directory of Open Access Journals (Sweden)

    M.K. Trivedi, BS, BA

    2017-03-01

    Full Text Available Melasma is a dysregulation of the homeostatic mechanisms that control skin pigmentation and excess pigment is produced. Traditional treatment approaches with topical medications and chemical peels are commonly used but due to the refractory and recurrent nature of melasma, patients often seek alternative treatment strategies such as laser and light therapy. Several types of laser and light therapy have been studied in the treatment of melasma. Intense pulsed light, low fluence Q-switched lasers, and non-ablative fractionated lasers are the most common lasers and light treatments that are currently performed. They all appear effective but there is a high level of recurrence with time and some techniques are associated with an increased risk for postinflammatory hyper- or hypopigmentation. The number and frequency of treatments varies by device type but overall, Q-switched lasers require the greatest number of treatment applications to see a benefit. Vascular-specific lasers do not appear to be effective for the treatment of melasma. Ablative fractionated lasers should be used with caution because they have a very high risk for postinflammatory hypo- and hyperpigmentation. The use of nonablative fractionated laser treatments compared with other laser and light options may result in slightly longer remission intervals. Picosecond lasers, fractional radiofrequency, and laser-assisted drug delivery are promising future approaches to treat melasma. The goal of this review is to summarize the efficacy and safety of the most commonly used laser and light therapies to treat melasma, briefly present future laser-based treatment options for patients with melasma, and provide recommendations for treatment on the basis of the reviewed information.

  7. Thermal blooming on laser propagation in an aspirating pipe

    Science.gov (United States)

    Zhu, Fuyin; Wang, Jihong; Ren, Ge; Tan, Yufeng; Zhu, Nengbing; Ai, Zhiwei

    2016-10-01

    Thermal blooming effect of gas on laser propagation can seriously degrade performance of far-field beam quality and energy distribution. Numerical simulation is carried out to study the influences of thermal blooming on laser propagation in line pipes. A physical model of thermal blooming effect of gas on laser propagation in an aspirating pipe is established. Axial flow and suction in the outlet are used to attenuate the thermal blooming effect. Based on the computational fluid dynamics (CFD) software, stable calculation of flow field is carried out first, then the optical field and the fluent field is coupling calculated by means of user defined function (UDF). The results show that radial flow is enhanced in the aspirating pipe and the index of refraction gradient caused by thermal blooming effect is decreased. It is indicated that the beam quality of the outlet is improved compared with the pipe model without aspirating. The optical path difference (OPD) distribution of the outlet is analyzed and decomposed by Zernike polynomials. It is shown that the defocus item of 4m aspirating pipe is decreased more than an order of magnitude compared with the 4m pipe without aspirating.

  8. Thermal Conductivity Based on Modified Laser Flash Measurement

    Science.gov (United States)

    Lin, Bochuan; Ban, Heng; Li, Chao; Scripa, Rosalia N.; Su, Ching-Hua; Lehoczky, Sandor L.

    2005-01-01

    The laser flash method is a standard method for thermal diffusivity measurement. It employs single-pulse heating of one side of a thin specimen and measures the temperature response of the other side. The thermal diffusivity of the specimen can be obtained based on a one-dimensional transient heat transfer analysis. This paper reports the development of a theory that includes a transparent reference layer with known thermal property attached to the back of sample. With the inclusion of heat conduction from the sample to the reference layer in the theoretical analysis, the thermal conductivity and thermal diffusivity of sample can be extracted from the temperature response data. Furthermore, a procedure is established to select two points from the data to calculate these properties. The uncertainty analysis indicates that this method can be used with acceptable levels of uncertainty.

  9. Clinical applications of laser therapy on the dental practice

    Science.gov (United States)

    Pinheiro, Antonio L. B.

    2004-09-01

    Dental practice consists of a series of laboring procedures which demands the use of several types of equipment and materials. Usually patient"s fears brings additional burden to the Dentists. The use of Lasers for treating and diagnosis in Dentistry is quite new comparing to other medical areas. Initially Laser technology was used as an alternative method for treating dental caries in order to substitute the use of the drill. Lately surgical Lasers have shown themselves very useful for treating several pathologies and began to be used as a powerful tool on the treatment of several conditions affecting the maxillofacial complex and later on, the era of the use of Laser therapy began. The advent of the diode Lasers made possible the introduction of small units at the dental office and Laser therapy was used to improve healing and later included also caries diagnosis. This paper discuss the use of Laser therapy on Restorative Dentistry, Periodondology, Oral and Maxillofacial Surgery, Oral implantology and other. Clinical and laboratorial experience has demonstrated that Laser therapy does improve the healing of both mineralized and soft tissues, reduces pain and inflammation, and also reduces both cost and length of the dental treatment.

  10. Role of laser and thermal ablation devices in the treatment of vascular diseases.

    Science.gov (United States)

    Litvack, F; Grundfest, W S; Papaioannou, T; Mohr, F W; Jakubowski, A T; Forrester, J S

    1988-05-09

    Since the first coronary angioplasty in 1977, both the number and complexity of interventional procedures have grown dramatically. Continuous-wave and pulsed lasers may further extend the capabilities of balloon angioplasty. Fiberoptic catheters may be used to transmit continuous-wave laser energy to ablate plaque via thermal mechanisms. Pulsed laser systems (such as the excimer) are technologically more complex than the continuous-wave systems, but may prove superior in small vessels given their ability to ablate plaque with minimal associated effects. On the other hand, modifications of the fiber-optic tip, such as the placement of a metal cap, have yielded even better results than current bare fiber systems. Such laser thermal techniques have proved a useful adjunct to balloon dilatation in peripheral vessels, but further research is necessary to determine their effect on coronary arteries. New, nonlaser technologies, however, may provide simpler power sources for thermal angioplasty. Although balloon angioplasty remains the cornerstone of interventional vascular therapy, new technologies should help to further expand the indications for nonsurgical interventions.

  11. Pilot point temperature regulation for thermal lesion control during ultrasound thermal therapy.

    Science.gov (United States)

    Liu, H L; Chen, Y Y; Yen, J Y; Lin, W L

    2004-03-01

    The fundamental goal of ultrasound thermal therapy is to provide proper thermal lesion formations for effective tumour treatment. The quality of the therapy depends mostly on its positional precision. To date, most ultrasound thermal therapy treatments have focused on the formation of power or temperature patterns. The non-linear and time-delay effects of thermal dose formation prohibit direct control of the thermal dose distribution. In the paper, the control of thermal lesions by regulation of the temperature of a pilot point is proposed. This scheme utilises the high correlation between temperature elevation and thermal dose at the forward boundary of thermal lesions. To verify the feasibility, a 2D ultrasound phased array system was used to generate thermal lesions of various sizes, and the temperature elevation required to generate a thermal dose threshold was investigated. Results showed that the required temperature elevation was found to be a reasonably constant value of 52.5 degrees C under differing conditions when the focal area was small. When the focal area under consideration was large, the required temperature elevation became a monotonic function of blood perfusion rate, ranging from 49.2 to 52.5 degrees C. When the reference temperature of the pilot point was set at a conservative value (52.5 degrees C), the thermal lesions were controlled precisely under a wide range of blood perfusion and power pattern changes, tested by using a more realistic model that takes into account thermal-induced attenuation and blood perfusion changes. This changed the complex thermal dose control problem into a simple temperature regulation problem, which makes implementation of thermal lesion control easier, giving the scheme a high potential for application to current ultrasound thermal therapy systems.

  12. Near "real" time magnetic resonance images as a monitoring system for interstitial laser therapy: experimental protocols

    Science.gov (United States)

    Castro, Dan J.; Farahani, Keyvan; Soudant, Jacques; Zwarun, Andrew A.; Lufkin, Robert B.

    1992-06-01

    The failure rate of cancer treatment remains unacceptably high, still being a leading cause of mortality in adults and children despite major advances over the past 50 years in the fields of surgery, radiation therapy and, more recently, chemo and immunotherapy. Surgical access to some deep tumors of the head and neck and other areas often require extensive dissections with residual functional and cosmetic deformities. Repeated treatment is not possible after maximum dose radiotherapy and chemotherapy is still limited by its systemic toxicity. An attractive solution to these problems would be the development of a new adjunctive method combining the best features of interstitial laser therapy for selective tumor destruction via minimally invasive techniques for access and 3-D magnetic resonance imaging (MRI) as a monitoring system for laser-tissue interactions. Interstitial laser therapy (ILT) via fiberoptics allow laser energy to be delivered directly into deeper tissues. However, this concept will become clinically useful only when noninvasive, accurate, and reproducible monitoring methods are developed to measure energy delivery to tissues. MRI has numerous advantages in evaluating the irreversible effects of laser treatment in tissues, since laser energy includes changes not only in the thermal motions of hydrogen protons within the tissue, but also in the distribution and mobility of water and lipids. These techniques should greatly improve the use of ILT in combination with MRI to allow treatment of deeper, more difficult to reach tumors of head and neck and other anatomical areas with a single needle stick.

  13. Thermal interaction of short-pulsed laser focused beams with skin tissues

    Energy Technology Data Exchange (ETDEWEB)

    Jiao Jian; Guo Zhixiong [Department of Mechanical and Aerospace Engineering, Rutgers, State University of New Jersey, Piscataway, NJ 08854 (United States)], E-mail: guo@jove.rutgers.edu

    2009-07-07

    Time-dependent thermal interaction is developed in a skin tissue cylinder subjected to the irradiation of a train of short laser pulses. The skin embedded with a small tumor is stratified as three layers: epidermis, dermis and subcutaneous fat with different optical, thermal and physiological properties. The laser beam is focused to the tumor site by an objective lens for thermal therapy. The ultrafast radiation heat transfer of the focused beam is simulated by the transient discrete ordinates method. The transient Pennes bio-heat equation is solved numerically by the finite volume method with alternating direction implicit scheme. Emphasis is placed on the characterization of the focused beam propagation and absorption and the temperature rise in the focal spot. The effects of the focal spot size and location, the laser power, and the bio-heat equation are investigated. Comparisons with collimated irradiation are conducted. The focused beam can penetrate a greater depth and produce higher temperature rise at the target area, and thus reduce the possibility of thermal damage to the surrounding healthy tissue. It is ideal for killing cancerous cells and small tumors.

  14. Thermal interaction of short-pulsed laser focused beams with skin tissues

    Science.gov (United States)

    Jiao, Jian; Guo, Zhixiong

    2009-07-01

    Time-dependent thermal interaction is developed in a skin tissue cylinder subjected to the irradiation of a train of short laser pulses. The skin embedded with a small tumor is stratified as three layers: epidermis, dermis and subcutaneous fat with different optical, thermal and physiological properties. The laser beam is focused to the tumor site by an objective lens for thermal therapy. The ultrafast radiation heat transfer of the focused beam is simulated by the transient discrete ordinates method. The transient Pennes bio-heat equation is solved numerically by the finite volume method with alternating direction implicit scheme. Emphasis is placed on the characterization of the focused beam propagation and absorption and the temperature rise in the focal spot. The effects of the focal spot size and location, the laser power, and the bio-heat equation are investigated. Comparisons with collimated irradiation are conducted. The focused beam can penetrate a greater depth and produce higher temperature rise at the target area, and thus reduce the possibility of thermal damage to the surrounding healthy tissue. It is ideal for killing cancerous cells and small tumors.

  15. Diffusing, side-firing, and radial delivery laser balloon catheters for creating subsurface thermal lesions in tissue

    Science.gov (United States)

    Chang, Chun-Hung; Fried, Nathaniel M.

    2016-02-01

    Infrared lasers have been used in combination with applied cooling methods to preserve superficial skin layers during cosmetic surgery. Similarly, combined laser irradiation and tissue cooling may also allow development of minimally invasive laser therapies beyond dermatology. This study compares diffusing, side-firing, and radial delivery laser balloon catheter designs for creation of subsurface lesions in tissue, ex vivo, using a near-IR laser and applied contact cooling. An Ytterbium fiber laser with 1075 nm wavelength delivered energy through custom built 18 Fr (6-mm-OD) balloon catheters incorporating either 10-mm-long diffusing fiber tip, 90 degree side-firing fiber, or radial delivery cone mirror, through a central lumen. A chilled solution was flowed through a separate lumen into 9-mm-diameter balloon to keep probe cooled at 7°C. Porcine liver tissue samples were used as preliminary tissue model for immediate observation of thermal lesion creation. The diffusing fiber produced subsurface thermal lesions measuring 49.3 +/- 10.0 mm2 and preserved 0.8 +/- 0.1 mm of surface tissue. The side-firing fiber produced subsurface thermal lesions of 2.4 +/- 0.9 mm2 diameter and preserved 0.5 +/- 0.1 mm of surface tissue. The radial delivery probe assembly failed to produce subsurface thermal lesions, presumably due to the small effective spot diameter at the tissue surface, which limited optical penetration depth. Optimal laser power and irradiation time measured 15 W and 100 s for diffusing fiber and 1.4 W and 20 s, for side-firing fiber, respectively. Diffusing and side-firing laser balloon catheter designs provided subsurface thermal lesions in tissue. However, the divergent laser beam in both designs limited the ability to preserve a thicker layer of tissue surface. Further optimization of laser and cooling parameters may be necessary to preserve thicker surface tissue layers.

  16. Thermal tests for laser Doppler perfusion measurements in Raynaud's syndrome

    Science.gov (United States)

    Kacprzak, Michal; Skora, A.; Obidzinska, J.; Zbiec, A.; Maniewski, Roman; Staszkiewicz, W.

    2004-07-01

    The laser Doppler method offers a non-invasive, real time technique for monitoring of blood perfusion in microcirculation. In practical measurements the perfusion index is given only in relative values. Thus, accurate and reproducible results can be only obtained when using a well controlled stimulation test. The aim of this study was evaluation of the thermal stimulation test, which is frequently used to investigate microcirculation in patients with Raynaud's syndrome. Three types of thermal tests, in which air or water with temperature in range 5°C - 40°C were used. Ten normal volunteers and fifteen patients with clinical symptoms of the primary Raynaud's syndrome were enrolled in this study. To estimate skin microcirculation changes during the thermal test, the multichannel laser Doppler system and laser Doppler scanner were used. The obtained results were analyzed from the point of view of the efficiency of these methods and the thermal provocative tests in differentiation of normal subjects and patient with Raynaud's syndrome.

  17. Benefits of Laser Therapy in Postmenopausal Vaginal Atrophy

    Science.gov (United States)

    Brînzan, Daniela; Pǎiuşan, Lucian; Daşcǎu, Voicu; Furǎu, Gheorghe

    2011-08-01

    Maybe the worst aspect of menopause is the decline of the quality of the sexual life. The aim of the study is to demonstrate the beneficial effects of laser therapy in comparison with topical application of estrogen preparations, for the treatment of vaginal atrophy and sexual dysfunctions induced by menopause. A total of 50 menopausal patients were examined during a one year period. The methods used for objectifying vaginal atrophy and sexual dysfunctions were history taking, local clinical exam and PAP smear. From this group, 40 patients had vaginal atrophy with sexual dysfunctions. They have been treated differently, being included in four groups: patients treated with local estrogens, patients treated with intravaginal laser therapy, patients treated with both laser therapy and estrogens, patients treated with estrogens and placebo laser therapy. Therapeutic benefit, improvement of vaginal atrophy and quality of sexual life, were objectified by anamnesis (questionnaire), local and general clinical examination and PAP smear. The best results have been obtained, by far, in the 3rd group, followed by the women treated only with laser. In conclusion, we can say that laser therapy is the best way for solving the sexual inconveniences of menopause.

  18. Identification of reduced-order thermal therapy models using thermal MR images: theory and validation.

    Science.gov (United States)

    Niu, Ran; Skliar, Mikhail

    2012-07-01

    In this paper, we develop and validate a method to identify computationally efficient site- and patient-specific models of ultrasound thermal therapies from MR thermal images. The models of the specific absorption rate of the transduced energy and the temperature response of the therapy target are identified in the reduced basis of proper orthogonal decomposition of thermal images, acquired in response to a mild thermal test excitation. The method permits dynamic reidentification of the treatment models during the therapy by recursively utilizing newly acquired images. Such adaptation is particularly important during high-temperature therapies, which are known to substantially and rapidly change tissue properties and blood perfusion. The developed theory was validated for the case of focused ultrasound heating of a tissue phantom. The experimental and computational results indicate that the developed approach produces accurate low-dimensional treatment models despite temporal and spatial noises in MR images and slow image acquisition rate.

  19. Low-power-laser therapy used in tendon damage

    Science.gov (United States)

    Strupinska, Ewa

    1996-03-01

    The following paper covers evaluation of low-power laser therapy results in chronic Achilles tendon damage and external Epicondylalia (tennis elbow). Fifty patients with Achilles damage (18 women and 32 men, age average 30, 24 plus or minus 10, 39 years) and fifty patients having external Epicondyalgiae (31 women and 19 men, age average 44, 36 plus or minus 10, 88 years) have been examined. The patients were irradiated by semiconductor infrared laser wavelength 904 nm separately or together with helium-neon laser wavelength 632.8 nm. The results of therapy have been based on the patient's interviews and examinations of patients as well as on the Laitinen pain questionnaire. The results prove analgesic effects in usage of low- power laser radiation therapy can be obtained.

  20. Laser drilling of thermal barrier coated jet-engine components

    Science.gov (United States)

    Sezer, H. K.

    Aero engine hot end components are often covered with ceramic Thermal Barrier Coatings (TBCs). Laser drilling in the TBC coated components can be a source of service life TBC degradation and spallation. The present study aims to understand the mechanisms of TBC delamination and develop techniques to drill holes without damaging the TBC, Nimonic 263 workpieces coated with TBC are used in the experiments. Microwave non-destructive testing (NDT) is employed to monitor the integrity of the coating /substrate interfaces of the post-laser drilled materials. A numerical modelling technique is used to investigate the role of melt ejection on TBC delamination. The model accounts for the vapour and the assist gas flow effects in the process. Broadly, melt ejection induced mechanical stresses for the TBC coating / bond coating and thermal effects for the bond coating / substrate interfaces are found the key delamination mechanisms. Experiments are carried out to validate the findings from the model. Various techniques that enable laser drilling without damaging the TBC are demonstrated. Twin jet assisted acute angle laser drilling is one successful technique that has been analysed using the melt ejection simulation. Optimisation of the twin jet assisted acute angle laser drilling process parameters is carried out using Design of Experiments (DoE) and statistical modelling approaches. Finally, an industrial case study to develop a high speed, high quality laser drilling system for combustor cans is described. Holes are drilled by percussion and trepan drilling in TBC coated and uncoated Haynes 230 workpieces. The production rate of percussion drilling is significantly higher than the trepan drilling, however metallurgical hole quality and reproducibility is poor. A number of process parameters are investigated to improve these characteristics. Gas type and gas pressure effects on various characteristics of the inclined laser drilled holes are investigated through theoretical

  1. Laser-driven ion accelerators for tumor therapy revisited

    Science.gov (United States)

    Linz, Ute; Alonso, Jose

    2016-12-01

    Ten years ago, the authors of this report published a first paper on the technical challenges that laser accelerators need to overcome before they could be applied to tumor therapy. Among the major issues were the maximum energy of the accelerated ions and their intensity, control and reproducibility of the laser-pulse output, quality assurance and patient safety. These issues remain today. While theoretical progress has been made for designing transport systems, for tailoring the plumes of laser-generated protons, and for suitable dose delivery, today's best lasers are far from reaching performance levels, in both proton energy and intensity to seriously consider clinical ion beam therapy (IBT) application. This report details these points and substantiates that laser-based IBT is neither superior to IBT with conventional particle accelerators nor ready to replace it.

  2. A novel diode laser system for photodynamic therapy

    DEFF Research Database (Denmark)

    Samsøe, E.; Andersen, P. E.; Petersen, P.;

    2001-01-01

    In this paper a novel diode laser system for photodynamic therapy is demonstrated. The system is based on linear spatial filtering and optical phase conjugate feedback from a photorefractive BaTiO3 crystal. The spatial coherence properties of the diode laser are significantly improved. The system...... is extracted in a high-quality beam and 80 percent of the output power is extracted through the fiber. The power transmitted through tile fiber scales linearly with the power of the laser diode. which means that a laser diode emitting 1.7 W multi-mode radiation would provide 1 W of optical power through a 50...

  3. Experimental investigation on the vascular thermal response to near-infrared laser pulses.

    Science.gov (United States)

    Li, Dong; Chen, Bin; Wu, Wenjuan; Ying, Zhaoxia

    2017-09-02

    Port wine stains (PWS) are congenital vascular malformations that progressively darken and thicken with age. To improve the effect of laser therapy in clinical practice, thermal response of blood vessel to a 1064 nm Nd:YAG laser with controlled energy doses and pulse durations was evaluated using the dorsal skin chamber model. A total of 137 vessels with 30-300 μm diameters were selected from the dorsal skin of the mouse to match those capillaries in port wine stains. Experimental results showed that the thermal response of blood vessels to 1064 nm laser irradiation can be classified as follows: vessel dilation, coagulation, constriction with decreased diameter, complete constriction, hemorrhage, and collagen damage with increasing laser radiant exposure. In most cases, that is, 83 of 137 blood vessels (60.6%), Nd:YAG laser irradiation was characterized by complete constriction (immediate blood vessel disappearance). To reveal the possible damage mechanisms and evaluate blood vessel photocoagulation patterns, theoretical investigation using bioheat transfer equation was conducted in mouse skin with a depth of 1000 μm. Complete constriction as the dominant thermal response as evidenced by uniform blood heating within the vessel lumen was noted in both experimental observation and theoretical investigation. To achieve the ideal clinical effect using the Nd:YAG laser treatment, the radiant exposure should not only be high enough to induce complete constriction of the blood vessels but also controlled carefully to avoid surrounding collagen damage. The short pulse duration of 1-3 ms is better than long pulse durations because hemorrhaging of small capillaries is occasionally observed postirradiation with pulse durations longer than 10 ms.

  4. Multifunctional Inorganic Nanoparticles: Recent Progress in Thermal Therapy and Imaging

    Directory of Open Access Journals (Sweden)

    Kondareddy Cherukula

    2016-04-01

    Full Text Available Nanotechnology has enabled the development of many alternative anti-cancer approaches, such as thermal therapies, which cause minimal damage to healthy cells. Current challenges in cancer treatment are the identification of the diseased area and its efficient treatment without generating many side effects. Image-guided therapies can be a useful tool to diagnose and treat the diseased tissue and they offer therapy and imaging using a single nanostructure. The present review mainly focuses on recent advances in the field of thermal therapy and imaging integrated with multifunctional inorganic nanoparticles. The main heating sources for heat-induced therapies are the surface plasmon resonance (SPR in the near infrared region and alternating magnetic fields (AMFs. The different families of inorganic nanoparticles employed for SPR- and AMF-based thermal therapies and imaging are described. Furthermore, inorganic nanomaterials developed for multimodal therapies with different and multi-imaging modalities are presented in detail. Finally, relevant clinical perspectives and the future scope of inorganic nanoparticles in image-guided therapies are discussed.

  5. Laser therapy in the treatment of urological diseases

    Science.gov (United States)

    Nelius, T.; de Riese, W. T.; Reiher, F.; Filleur, S.; Allhoff, E. P.

    2006-02-01

    Applications of lasers (light amplification by stimulated emission of radiation) in various disciplines of medicine including Urology are well developed. Urology is among the medical specialties that apply many different types of laser systems to treat a broad spectrum of clinical conditions ranging from genital, bladder and urethral tumors to the treatment of benign prostate hyperplasia (BPH), urethral strictures, and stones. The specific application of various laser systems depends on the characteristics of the laser itself, delivery media for the beams, laser-tissue interaction and the desired effect. These complex conditions require an intensive and continuous exchange of information between non-medical researchers and physicians to verify "what is currently technically possible and what is medically needed". Only this exchange can lead to the development of new laser systems. While lasers have become the treatment of choice in some conditions, they could not, despite excellent clinical results, replace conventional therapy options in others. Nonetheless, the use and the introduction of lasers of different wavelengths forces urologists to keep step with the fast developing laser technology. This paper reviews current indications for clinical laser applications relevant to urology and the advantages and disadvantages of using lasers for the management of various urological lesions.

  6. Thermal Effect in KTP Crystals During High Power Laser Operation

    Institute of Scientific and Technical Information of China (English)

    YAO Jian-Quan; YU Yi-Zhong; CHEN Jin; ZHANG Fan; WANG Peng; WANG Tao; ZHANG Bai-Gang

    2001-01-01

    We report on the theoretical and experimental studies of the thermal effect of the KTP crystal during high power operation. From the dependence of the refractive index temperature coefficients on wavelength, the dependence of the optimum phase-matching angles on temperature is derived. In the experiment, the angle of the frequency-doubled KTP crystal is tilted to compensate for the thermal effect and to obtain △φ = 0.7° when the green laser output power is 30 W and the KTP crystal temperature is about 80°C. We obtained the highest stable output power greater than 40 W with an L-shaped flat-flat intracavity frequency-doubled Nd:YAG laser. The experimental results are very consistent with the theoretical analysis.

  7. Endovenous laser therapy for varicose veins

    NARCIS (Netherlands)

    Disselhoff, B.C.V.M.

    2008-01-01

    This thesis describes the technique of endovenous laser ablation and the outcome of various series of patients with varicose veins due to reflux in the great saphenous vein, treated by endovenous laser ablation or cryostripping in a single-centre study. This study has shown clear advantages of endov

  8. Thermal degradation of PA66 during laser transmission welding

    Science.gov (United States)

    Wang, Xiao; Guo, Dehui; Chen, Guochun; Jiang, Hairong; Meng, Dongdong; Yan, Zhang; Liu, Huixia

    2016-09-01

    The thermal degradation of materials strongly influences the weld strength in laser transmission welding (LTW). Weld strength decreases at high temperatures because of material thermal degradation. Hence, it is necessary to investigate this phenomenon. Thermal degradation of polyamide 66 (PA66) was predicted by combining a pyrolysis kinetic model with a 3-D transient thermal model. Thermogravimetric analysis (TGA) was used to study the pyrolysis characteristic of PA66. The TGA data were used to obtain kinetic parameters of PA66 using an nth order model in MATLAB. In addition, material conversion as a function of temperature (time) was analyzed using this kinetic reaction model containing the relevant kinetic parameters. A 3-D transient thermal model based on a volumetric heat source was developed. The temperature-time data of the point located at the maximum temperature was predicted through this thermal analysis model under different weld parameters. This study demonstrates that the predicted power at which the material starts to degrade is generally consistent with the power at which shear strength begins to decrease. The present studies lay a theoretical foundation for the investigation of thermal degradation during LTW.

  9. Thermal modeling of laser-addressed liquid-crystal displays

    Science.gov (United States)

    Evans, K. E.; Nkansah, M. A.

    1990-06-01

    Optical-absorption calculations and finite-element methods are used to calculate time-dependent temperature profiles in two contrasting laser-addressed liquid-crystal displays. It is shown that the presence of conducting electrode layers has a significant effect on the temperature profiles both by affecting the optical-absorption characteristics of the cell and the resulting thermal conductivity. It is shown that efficient optical absorption does not necessarily result in the best cell-addressing performance.

  10. Breaking two laser axioms: Lasing without inversion and thermal equilibrium

    CERN Document Server

    Weill, Rafi; Levit, Boris; Zhurahov, Michael; Fischer, Baruch

    2016-01-01

    It is well known that lasing requires population inversion and that lasers are not in thermal equilibrium (TE). There is a singular example for lasing without inversion (LWI) based on a subtle quantum interference effect that was presented and observed many years ago but has not become a spread and practical method [1-6]. Photons were found to be in TE in a special microcavity but not in a lasing regime [7,8]. Here we report on experimental findings that break these two axioms on lasers. We show LWI and TE in regular lasers with standard erbium-doped fibers (edf) at the 1550nm wavelength regime. The TE is observed for photons in edf cavities and even in open fibers in broad wavelength ranges up to ~200nm. The thermal-LWI results from photon thermalization that spreads the spectrum and transforms photons from low to high wavelengths where the emission cross section is larger than the absorption and compensates for the lower upper-state population. The experimental results are supported by a theoretical analysi...

  11. Endovascular Laser Therapy for Varicose Veins

    Science.gov (United States)

    2010-01-01

    Executive Summary Objective The objective of the MAS evidence review was to conduct a systematic review of the available evidence on the safety, effectiveness, durability and cost–effectiveness of endovascular laser therapy (ELT) for the treatment of primary symptomatic varicose veins (VV). Background The Ontario Health Technology Advisory Committee (OHTAC) met on November 27, 2009 to review the safety, effectiveness, durability and cost-effectiveness of ELT for the treatment of primary VV based on an evidence-based review by the Medical Advisory Secretariat (MAS). Clinical Condition VV are tortuous, twisted, or elongated veins. This can be due to existing (inherited) valve dysfunction or decreased vein elasticity (primary venous reflux) or valve damage from prior thrombotic events (secondary venous reflux). The end result is pooling of blood in the veins, increased venous pressure and subsequent vein enlargement. As a result of high venous pressure, branch vessels balloon out leading to varicosities (varicose veins). Symptoms typically affect the lower extremities and include (but are not limited to): aching, swelling, throbbing, night cramps, restless legs, leg fatigue, itching and burning. Left untreated, venous reflux tends to be progressive, often leading to chronic venous insufficiency (CVI). A number of complications are associated with untreated venous reflux: including superficial thrombophlebitis as well as variceal rupture and haemorrhage. CVI often results in chronic skin changes referred to as stasis dermatitis. Stasis dermatitis is comprised of a spectrum of cutaneous abnormalities including edema, hyperpigmentation, eczema, lipodermatosclerosis and stasis ulceration. Ulceration represents the disease end point for severe CVI. CVI is associated with a reduced quality of life particularly in relation to pain, physical function and mobility. In severe cases, VV with ulcers, QOL has been rated to be as bad or worse as other chronic diseases such as

  12. Thermal-mechanical modeling of laser ablation hybrid machining

    Science.gov (United States)

    Matin, Mohammad Kaiser

    2001-08-01

    Hard, brittle and wear-resistant materials like ceramics pose a problem when being machined using conventional machining processes. Machining ceramics even with a diamond cutting tool is very difficult and costly. Near net-shape processes, like laser evaporation, produce micro-cracks that require extra finishing. Thus it is anticipated that ceramic machining will have to continue to be explored with new-sprung techniques before ceramic materials become commonplace. This numerical investigation results from the numerical simulations of the thermal and mechanical modeling of simultaneous material removal from hard-to-machine materials using both laser ablation and conventional tool cutting utilizing the finite element method. The model is formulated using a two dimensional, planar, computational domain. The process simulation acronymed, LAHM (Laser Ablation Hybrid Machining), uses laser energy for two purposes. The first purpose is to remove the material by ablation. The second purpose is to heat the unremoved material that lies below the ablated material in order to ``soften'' it. The softened material is then simultaneously removed by conventional machining processes. The complete solution determines the temperature distribution and stress contours within the material and tracks the moving boundary that occurs due to material ablation. The temperature distribution is used to determine the distance below the phase change surface where sufficient ``softening'' has occurred, so that a cutting tool may be used to remove additional material. The model incorporated for tracking the ablative surface does not assume an isothermal melt phase (e.g. Stefan problem) for laser ablation. Both surface absorption and volume absorption of laser energy as function of depth have been considered in the models. LAHM, from the thermal and mechanical point of view is a complex machining process involving large deformations at high strain rates, thermal effects of the laser, removal of

  13. Laser therapy for the restoration of vaginal function.

    Science.gov (United States)

    Gambacciani, Marco; Palacios, Santiago

    2017-05-01

    Laser therapy has a therapeutic role in various medical conditions and most recently has gained interest as a non-hormonal treatment for genitourinary syndrome of menopause (GSM) and as a non-invasive option for stress urinary incontinence (SUI). Several therapies are available to alleviate GSM symptoms, including hormonal and non-hormonal products. Both microablative fractional CO2 laser and the non-ablative vaginal Er:YAG laser (VEL) induce morphological changes in the vaginal tissues, and data from non-randomized clinical trials suggest that laser therapy can alleviate vaginal dryness and dyspareunia. VEL has been reported to improve SUI as well as vaginal prolapse. Although large randomized trials have not been reported, the evidence suggests that VEL can be offered as a safe and efficacious alternative to hormone replacement therapy (HRT) for GSM, as well as a first-line treatment for mild to moderate SUI, before surgical procedures are resorted to. Randomized studies are needed to compare laser treatments with other therapies, as well as to assess the duration of the therapeutic effects and the safety of repeated applications. Research is presently evaluating both an automated robotic probe for VEL treatments and an intraurethral probe for the treatment of severe and type III SUI. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Effects of thermal therapy combining sauna therapy and underwater exercise in patients with fibromyalgia.

    Science.gov (United States)

    Matsumoto, Shuji; Shimodozono, Megumi; Etoh, Seiji; Miyata, Ryuji; Kawahira, Kazumi

    2011-08-01

    Fibromyalgia syndrome (FMS) is a chronic disorder that is characterized by widespread pain with localized tenderness. We aimed to investigate whether thermal therapy combining sauna therapy and underwater exercise improved pain, symptoms, and quality of life (QOL) in FMS patients. Forty-four female FMS patients who fulfilled the American College of Rheumatology (ACR) criteria received 12-week thermal therapy program comprising sauna therapy once daily for 3 days/week and underwater exercise once daily for 2 days/week. Pain, symptoms, and QOL were assessed using a pain visual analog scale (VAS), a fibromyalgia impact questionnaire (FIQ), and a short form 36-item questionnaire (SF-36), respectively. All of the patients reported significant reductions in pain and symptoms of 31-77% after the 12-week thermal therapy program, which remained relatively stable (28-68%) during the 6-month follow-up period (that is, the thermal therapy program improved both the short-term and the long-term VAS and FIQ scores). Improvements were also observed in the SF-36 score. Thermal therapy combining sauna therapy and underwater exercise improved the QOL as well as the pain and symptoms of FMS patients.

  15. Numerical investigation of thermal response of laser-irradiated biological tissue phantoms embedded with gold nanoshells.

    Science.gov (United States)

    Phadnis, Akshay; Kumar, Sumit; Srivastava, Atul

    2016-10-01

    The work presented in this paper focuses on numerically investigating the thermal response of gold nanoshells-embedded biological tissue phantoms with potential applications into photo-thermal therapy wherein the interest is in destroying the cancerous cells with minimum damage to the surrounding healthy cells. The tissue phantom has been irradiated with a pico-second laser. Radiative transfer equation (RTE) has been employed to model the light-tissue interaction using discrete ordinate method (DOM). For determining the temperature distribution inside the tissue phantom, the RTE has been solved in combination with a generalized non-Fourier heat conduction model namely the dual phase lag bio-heat transfer model. The numerical code comprising the coupled RTE-bio-heat transfer equation, developed as a part of the current work, has been benchmarked against the experimental as well as the numerical results available in the literature. It has been demonstrated that the temperature of the optical inhomogeneity inside the biological tissue phantom embedded with gold nanoshells is relatively higher than that of the baseline case (no nanoshells) for the same laser power and operation time. The study clearly underlines the impact of nanoshell concentration and its size on the thermal response of the biological tissue sample. The comparative study concerned with the size and concentration of nanoshells showed that 60nm nanoshells with concentration of 5×10(15)mm(-3) result into the temperature levels that are optimum for the irreversible destruction of cancer infected cells in the context of photo-thermal therapy. To the best of the knowledge of the authors, the present study is one of the first attempts to quantify the influence of gold nanoshells on the temperature distributions inside the biological tissue phantoms upon laser irradiation using the dual phase lag heat conduction model.

  16. Laser therapy of pigmented lesions: pro and contra.

    Science.gov (United States)

    Bukvić Mokos, Zrinka; Lipozenčić, Jasna; Ceović, Romana; Stulhofer Buzina, Daška; Kostović, Krešimir

    2010-01-01

    Although frequently performed, laser removal of pigmented lesions still contains certain controversial issues. Epidermal pigmented lesions include solar lentigines, ephelides, café au lait macules and seborrheic keratoses. Dermal lesions include melanocytic nevi, blue nevi, drug induced hyperpigmentation and nevus of Ota and Ito. Some lesions exhibit both an epidermal and dermal component like Becker's nevus, postinflammatory hyperpigmentations, melasma and nevus spilus. Due to the wide absorption spectrum of melanin (500-1100 nm), several laser systems are effective in removal of pigmented lesions. These lasers include the pigmented lesion pulsed dye laser (510 nm), the Q-switched ruby laser (694 nm), the Q-switched alexandrite laser (755 nm) and the Q-switched Nd:YAG laser (1064 nm), which can be frequency-doubled to produce visible green light with a wavelength of 532 nm. The results of laser therapy are usually successful. However, there are still many controversies regarding the use of lasers in treating certain pigmented lesions. Actually, the essential question in removing pigmented lesions with lasers is whether the lesion has atypical features or has a malignant potential. Dermoscopy, used as a routine first-level diagnostic technique, is helpful in most cases. If there is any doubt whether the lesion is benign, then a biopsy for histologic evaluation is obligatory.

  17. Platelet rich plasma versus laser therapy in lateral epicondylitis of elbow

    Directory of Open Access Journals (Sweden)

    Gyaneshwar Tonk

    2014-01-01

    Conclusions: Treatment of patients with chronic lateral epicondylitis with PRP extract reduced pain and significantly increased function, exceeding the effect of low level laser therapy on long term followup. Low-level laser therapy is better in the short term period, but on long term followup injection PRP therapy is better than laser therapy in lateral epicondylitis.

  18. Laser therapy, tissue cicatrization and angiogenesis

    National Research Council Canada - National Science Library

    José Carlos Tatmatsu Rocha

    2004-01-01

    ..., increment of the fibroblastic activity and colagenogenesis. The changes that come from the Laser action in the processes of regeneration are still in a phase of being developed, therefore, the mechanisms of action are not completely clarified...

  19. Thermal stresses in functionally graded materials caused by a laser thermal shock

    Energy Technology Data Exchange (ETDEWEB)

    Elperin, T.; Rudin, G. [Department of Mechanical Engineering, Pearlstone Center for Aeronautical Engineering Studies Ben-Gurion University of the Negev, Beer-Sheva (Israel)

    2002-08-01

    Mathematical simulation of a thermal shock method for reliability testing of functionally graded material (FGM) is performed with the end to determine operating parameters of the testing device (power of a laser, laser beam radius, duration of heating) and to investigate the effect of the composition of FGM on a magnitude of thermal stresses in a coating. An analytical method for solution of the thermal elasticity problem is developed whereby the approach of a multilayer plate is used for determining temperature and thermal stresses distributions in a coating. We considered the limiting case of the obtained solution when the thickness of a layer is infinitesimally small and the number of layers tends to infinity. This procedure allowed us to obtain the thermal stresses distribution in a FGM coating. The results for the FGM coating composed of WC (tungsten carbide) ceramics and HS-steel are presented. It is showed that variation of the volume content of ceramics strongly affects thermal stresses in a coating and they decrease significantly in the case of the uniform spatial distribution of ceramics. (orig.)

  20. Laser therapy, tissue cicatrization and angiogenesis

    OpenAIRE

    José Carlos Tatmatsu Rocha

    2004-01-01

    The Laser´s radiation of low power with specters of electromagnetic waves located in the bands between 690 the 940 nm became object of innumerous researches focusing, in special, its angiogenic action, increment of the fibroblastic activity and colagenogenesis. The changes that come from the Laser action in the processes of regeneration are still in a phase of being developed, therefore, the mechanisms of action are not completely clarified. The purpose of this article is to update the studie...

  1. Excimer laser therapy and narrowband ultraviolet B therapy for exfoliative cheilitis

    Directory of Open Access Journals (Sweden)

    Bhavnit K. Bhatia, BA

    2015-06-01

    Conclusion: Excimer laser therapy is a well-tolerated and effective treatment for refractory exfoliative cheilitis with twice weekly laser treatments of up to 700 mJ/cm2. Transitioning to the hand-held narrowband UVB device was also an effective maintenance strategy.

  2. Single shot thermometry using laser induced thermal grating

    Science.gov (United States)

    Qu, Pubo; Guan, Xiaowei; Zhang, Zhenrong; Wang, Sheng; Li, Guohua; Ye, Jingfeng; Hu, Zhiyun

    2015-05-01

    With the concern of environmental protection and reducing the fossil fuel consumption, combustion processes need to be more efficient and less contaminable. Therefore, the ability to obtain important thermophysical parameters is crucial to combustion research and combustor design. Traditional surveying techniques were difficult to apply in a confined space, especially the physically intrusions of detectors can alter the combustion processes. Laser-based diagnostic techniques, like CARS, SVRS, PLIF and TDLAS, allow the in situ, non-intrusive, spatially and temporally resolved measurements of combustion parameters in hostile environments. We report here a new non-intrusive optical diagnostic technique, based on laser-induced thermal grating. Thermal gratings generated in NO2/N2 binary mixtures, arise from the nonlinear interaction between the medium and the light radiation from the interference of two pulsed, frequency-doubled Nd:YAG lasers (532 nm). This leads to the formation of a dynamic grating through the resonant absorption and the subsequent collisional relaxation. By the temporally resolved detection of a continuous wave, frequency-doubled Nd:YVO4 probe laser beam (671 nm) diffracted by LITG. The temporal behavior of the signal is a function of the local temperature and other properties of gas, various parameters of the target gas can be extracted by analyzing the signal. The accurate singleshot temperature measurements were carried out at different test conditions using a stainless steel pressurized cell, data averaged on 100 laser shots were compared with simultaneously recorded thermocouple data, and the results were consistent with each other. The LITG signal is shown to grow with increasing the gas pressure and is spatially coherent, which makes the LITG thermometry technique a promising candidate in high pressure environments.

  3. Low-intensity laser therapy of pleuritis

    Directory of Open Access Journals (Sweden)

    Milojević Momir

    2003-01-01

    Full Text Available Introduction Low-intensity lasers have been utilized in medicine in two ways: for local stimulation and for stimulation of acupuncture points. Literature data reveal that this method has been indiscriminately applied in physiatry, rheumatology, gynecology, dermatology, otorhinolaryngology, in diverse acute and chronic pains, inflammations, vascular disorders, angina pectoris, bronchial asthma. Most commonly reported clinical effects are analgesia, spasmolytic and anti-inflammatory effects, as well as faster wound and bone healing. Material and methods This prospective study analyses effects of laser biostimulation on patients with pleurisy. The analysis included 25 patients treated at the Institute of Lung Diseases in Sremska Kamenica during 2000, 2001 and 2002. Appart from conservative treatment, these patients were treated with laser biostimulation of acupuncture points and local region for ten days. During treatment, changes of present clinical signs, general symptoms, radiological findings, as well as changes of some relevant biochemical parameters were recorded. Results Results were compared with the control group which included the same number of patients, who differed from the examined group only by not being exposed to laser biostimulation. The examined group of patients with pleuritis presented with quicker resorption of pleural effusion, less pleural adhesions, more significant decrease of clinical symptoms, especially pain, as well as more significant increase of cortisol and immunoglobulin A and decrease of circulating immune complexes (CIC, leukocytes and sedimentation rate than the control group. Discussion Mechanisms of laser biostimulation in treatment of pleurisy were described in detail and the obtained results were correlated to those reported by other authors. Conclusion 1. Patients with pleurisy undergoing laser stimulation presented with faster resorption of effusion and remission of the subjective symptoms, as well as

  4. Thermal therapeutic method for selective treatment of deep-lying tissue by combining laser and high-intensity focused ultrasound energy.

    Science.gov (United States)

    Kim, Haemin; Kang, Jeeun; Chang, Jin Ho

    2014-05-01

    Photothermal therapy is performed by delivering laser radiation into the target lesion containing tissue chromophores so as to induce localized heating. For high treatment efficacy, the laser wavelength should be selected to maximize the absorption of incident laser radiation in the tissue chromophores. However, even with the optimal laser wavelength, both the absorption and the scattering of laser energy in tissue openly hamper treatment efficacy in deep-lying lesions. To overcome the limitation, we propose a dual thermal therapeutic method in which both laser and acoustic energies are transmitted to increase therapeutic depth while maintaining high target selectivity of photothermal therapy. Through skin-mimicking phantom experiments, it was verified that the two different energies are complementary in elevation of tissue temperature, and the treatment depth using laser radiation is increased along with acoustic energy.

  5. Regulation of miRNA Expression by Low-Level Laser Therapy (LLLT) and Photodynamic Therapy (PDT)

    OpenAIRE

    Miya Ishihara; Shinpei Okawa; Toshihiro Kushibiki; Takeshi Hirasawa

    2013-01-01

    Applications of laser therapy, including low-level laser therapy (LLLT), phototherapy and photodynamic therapy (PDT), have been proven to be beneficial and relatively less invasive therapeutic modalities for numerous diseases and disease conditions. Using specific types of laser irradiation, specific cellular activities can be induced. Because multiple cellular signaling cascades are simultaneously activated in cells exposed to lasers, understanding the molecular responses within cells will a...

  6. Role of laser therapy in post herpetic neuralgia

    Directory of Open Access Journals (Sweden)

    Mann S

    1999-01-01

    Full Text Available The efficacy of combi laser therpay was evaluated in fifty cases of post neuralgia (PHN of different age groups (31 to 81 years and with varying duration of illness from 2 months to 4 and a half years in the present study. The affected areas were irradiated from a distance of 5 cms. using the probe of 12x70 watts at a frequency of 1000 Hz. each area being exposed for a time period of 5 minutes and 6 seconds. In each case the combi laser therapy was given for 15 consecutive days and therapeutic effect of the therapy was evaluated after 5th, 10th and 15th laser application during the treatment with the help of visual analouge scale (VAS. Patients started responding to the therapy after an average of 3.28 laser applications and VAS steadily decreased as the therapy progressed. After completion of therapy, 43 (86% out of 50 cases showed excellent relief (76-100% and remaining 7 (14% cases showed partial relief, 4(8% cases with good relief (51-75%, 2 (4% cases with fair relief (26-50% and 1(2% case with poor relief (1-25%. Partial relief in our 7 cases could be due to multiple factors like prolonged duration of illness, involvement of ophthalmic division of trigeminal nerve and formation of scarring and keloids. No side effects were observed during the treatment as well as duing the follow up period of 8 weeks.

  7. Laser therapy, tissue cicatrization and angiogenesis

    Directory of Open Access Journals (Sweden)

    José Carlos Tatmatsu Rocha

    2004-03-01

    Full Text Available The Laser´s radiation of low power with specters of electromagnetic waves located in the bands between 690 the 940 nm became object of innumerous researches focusing, in special, its angiogenic action, increment of the fibroblastic activity and colagenogenesis. The changes that come from the Laser action in the processes of regeneration are still in a phase of being developed, therefore, the mechanisms of action are not completely clarified. The purpose of this article is to update the studies and results in the previous researches related to the performance of the Lasers of low intensity in a process that help to establish the tissue cicatrization attempting to serve as a source of data for future investigations.

  8. Microbiological estimate of parodontitis laser therapy efficiency

    Science.gov (United States)

    Mamedova, F. M.; Akbarova, Ju. A.; Bajenov, L. G.; Arslanbekov, T. U.

    1995-04-01

    In this work was carried out microbiological estimate the efficiency of ultraviolet and He-Ne laser radiation at the treatment of parodontitis. 90 persons was investigated with parodontitis of middle serious diagnosis. The optimal regimes of ultraviolet radiation influence on various micro-organisms discharged from pathologic tooth pocket (PTP) were determined. On the base of specils microflora composition study and data of microbic PTP dissemination owe may conclude that the complex He- Ne and ultraviolet laser radiation show the most pronounced antimicrobic effect.

  9. Thermal melting and ablation of silicon by femtosecond laser radiation

    Energy Technology Data Exchange (ETDEWEB)

    Ionin, A. A.; Kudryashov, S. I., E-mail: sikudr@lebedev.ru; Seleznev, L. V.; Sinitsyn, D. V. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Bunkin, A. F.; Lednev, V. N.; Pershin, S. M. [Russian Academy of Sciences, General Physics Institute (Russian Federation)

    2013-03-15

    The space-time dynamics of thermal melting, subsurface cavitation, spallative ablation, and fragmentation ablation of the silicon surface excited by single IR femtosecond laser pulses is studied by timeresolved optical reflection microscopy. This dynamics is revealed by monitoring picosecond and (sub)nanosecond oscillations of probe pulse reflection, which is modulated by picosecond acoustic reverberations in the dynamically growing surface melt subjected to ablation and having another acoustic impedance, and by optical interference between the probe pulse replicas reflected by the spalled layer surface and the layer retained on the target surface. The acoustic reverberation periods change during the growth and ablation of the surface melt film, which makes it possible to quantitatively estimate the contributions of these processes to the thermal dynamics of the material surface. The results on the thermal dynamics of laser excitation are supported by dynamic measurements of the ablation parameters using noncontact ultrasonic diagnostics, scanning electron microscopy, atomic force microscopy, and optical interference microscopy of the modified regions appearing on the silicon surface after ablation.

  10. [Equipment for low reactive level laser therapy including that for light therapy].

    Science.gov (United States)

    Saeki, Shigeru

    2006-09-01

    Equipments used for light therapy include machinery used for irradiation by low reactive level laser, xenon light and linear polarized infra-red ray. Low reactive level laser is divided into two types of laser according to the medium by which laser is obtained ; semiconductor laser and helium-neon laser. Low reactive level laser has only one wave length and produces analgesia by action of light itself. On the other hands, Xenon light and linear polarized infra-red ray produce analgesia by warming effect induced by light in addition to the action of light itself. There are four methods of irradiation by these light sources; irradiation of acupuncture points, of trigger points, along nerves causing pain and of stellate ganglion area. Indication for light therapy includes various kinds of diseases such as herpes zoster, post herpetic neuralgia, cervical pain, lumbago due to muscle contracture, complex regional pain syndrome, arthralgia etc. However, we have to know that light therapy does not exert analgesic effects equally to all patients. But light therapy does not accompany pain and rarely shows any side effects. Therefore it is thought to be an alternative for patients who reject injection or patients who are not indicated for nerve block because of patients' conditions such as bleeding tendency.

  11. On-line laser spectroscopy with thermal atomic beams

    CERN Document Server

    Thibault, C; De Saint-Simon, M; Duong, H T; Guimbal, P; Huber, G; Jacquinot, P; Juncar, P; Klapisch, Robert; Liberman, S; Pesnelle, A; Pillet, P; Pinard, J; Serre, J M; Touchard, F; Vialle, J L

    1981-01-01

    On-line high resolution laser spectroscopy experiments have been performed in which the light from a CW tunable dye laser interacts at right angles with a thermal atomic beam. /sup 76-98/Rb, /sup 118-145 /Cs and /sup 208-213/Fr have been studied using the ionic beam delivered by the ISOLDE on-line mass separator at CERN while /sup 30-31/Na and /sup 38-47/K have been studied by setting the apparatus directly on-line with the PS 20 GeV proton beam. The principle of the method is briefly explained and some results concerning nuclear structure are given. The hyperfine structure, spins and isotope shifts of the alkali isotopes and isomers are measured. (8 refs).

  12. [Differential therapy of hemangiomas--when cryotherapy, laser therapy or operation?].

    Science.gov (United States)

    Grantzow, R

    2001-01-01

    Hemangiomas are the most common soft tissue tumours in childhood, which arise after birth, grow for several months and regress spontaneously. Serious problems can occur with closure of the eye resulting in amblyopia or with psychologica problems due to disfiguring of the face. Therapeutic possibilities are cryo therapy, laser therapy and surgical removal. Cryotherapy can be used for small and flat hemangiomas. Bigger hemangiomas are treated with the Nd-YAG laser. Its effect is an acceleration of involution. Typical residues of hemangiomas must be secondarily corrected surgically. Indications for primary surgical therapy are hemangiomas of the eye lid and in the scalp.

  13. 三种热效应激光汽化兼热杀癌的理论计算与应用方法讨论%The theoretical calculations of vaporizing and heat-killing therapy of cancer with the three thermal-effect lasers and discussion on the applied methods

    Institute of Scientific and Technical Information of China (English)

    田晓明; 冯永振

    2001-01-01

    本文根据激光汽化兼热杀癌肿瘤的理论模型〔1,2〕,对三种常见热效应激光进行了理论计算和结果对比,讨论了在较大汽化域情况下尽可能减少照射治疗时间的应用方法和措施,为激光治疗较大肿瘤提供具体理论参考数据。%Based on the theoretical models of vaporizing and heat-killing therapy of cancer with laser,the theoretical calculations of three common thermal-effect lasers have been made,and the results are shown and compared in this paper.We discuss on the applied methods to get the irradiating time as short as possible under more large vaporizing area.These theoretical calculated data will be valuable for reference.

  14. Thermal conductivity measurements of laser crystals by infrared thermography. Application to Nd:doped crystals

    OpenAIRE

    Didierjean, Julien; Hérault, Emilie; Balembois, François; Georges, Patrick

    2008-01-01

    International audience; We present a thermal conductivity measurement method for laser crystals based on thermal mapping of the crystal face by an infrared camera. Those measurements are performed under end-pumping of the laser crystal and during laser operation. The calculation of the fraction of pump power converted into heat is therefore simplified, and it is possible to link easily the temperature in the crystal to the thermal conductivity. We demonstrate the efficiency of this measuremen...

  15. Influence of heat transfer on thermal effects of the endpumped laser crystal

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yin-ke; HE Yan-ping; ZAN Hui-ping; YANG Hao

    2010-01-01

    A thermal model of crystal is established. The temperature field differential equation of the diode-end-pumped laser crystal with circular cross-section and new boundary conditions, in which the convection heat transfer is supposed to exist between laser crystal ends and air, is established. The analytical expressions of temperature field, thermal distortion and additional optical path difference (OPD) of crystal are obtained. By numerical calculation, the influence of heat transfer on the thermal effects of laser crystal Nd:YAG is studied. Results show that crystal's thermal effects, including temperature field, thermal distortion, OPD and thermal focal length, are all weakened as the heat transfer through ends of crystal is strengthened. This conclusion could be used to control thermal effects of laser crystal and improve laser working stability.

  16. Thermal annealing of laser damage precursors on fused silica surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Shen, N; Miller, P E; Bude, J D; Laurence, T A; Suratwala, T I; Steele, W A; Feit, M D; Wang, L L

    2012-03-19

    Previous studies have identified two significant precursors of laser damage on fused silica surfaces at fluenes below {approx} 35 J/cm{sup 2}, photoactive impurities in the polishing layer and surface fractures. In the present work, isothermal heating is studied as a means of remediating the highly absorptive, defect structure associated with surface fractures. A series of Vickers indentations were applied to silica surfaces at loads between 0.5N and 10N creating fracture networks between {approx} 10{micro}m and {approx} 50{micro}m in diameter. The indentations were characterized prior to and following thermal annealing under various times and temperature conditions using confocal time-resolved photo-luminescence (CTP) imaging, and R/1 optical damage testing with 3ns, 355nm laser pulses. Significant improvements in the damage thresholds, together with corresponding reductions in CTP intensity, were observed at temperatures well below the glass transition temperature (T{sub g}). For example, the damage threshold on 05.N indentations which typically initiates at fluences <8 J/cm{sup 2} could be improved >35 J/cm{sup 2} through the use of a {approx} 750 C thermal treatment. Larger fracture networks required longer or higher temperature treatment to achieve similar results. At an annealing temperature > 1100 C, optical microscopy indicates morphological changes in some of the fracture structure of indentations, although remnants of the original fracture and significant deformation was still observed after thermal annealing. This study demonstrates the potential of using isothermal annealing as a means of improving the laser damage resistance of fused silica optical components. Similarly, it provides a means of further understanding the physics associated with optical damage and related mitigation processes.

  17. The computer simulation of laser proton acceleration for hadron therapy

    Science.gov (United States)

    Lykov, Vladimir; Baydin, Grigory

    2008-11-01

    The ions acceleration by intensive ultra-short laser pulses has interest in views of them possible applications for proton radiography, production of medical isotopes and hadron therapy. The 3D relativistic PIC-code LegoLPI is developed at RFNC-VNIITF for modeling of intensive laser interaction with plasma. The LegoLPI-code simulations were carried out to find the optimal conditions for generation of proton beams with parameters necessary for hadrons therapy. The performed simulations show that optimal for it may be two-layer foil of aluminum and polyethylene with thickness 100 nm and 50 nm accordingly. The maximum efficiency of laser energy transformation into 200 MeV protons is achieved on irradiating these foils by 30 fs laser pulse with intensity about 2.10^22 W/cm^2. The conclusion is made that lasers with peak power about 0.5-1PW and average power 0.5-1 kW are needed for generation of proton beams with parameters necessary for proton therapy.

  18. Determination of Cationic Surfactant by Laser Thermal Lens Spectrometry

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A novel method for the determination of cationic surfactant by laser thermal lens spectrometry was developed. It was based on the reaction between 1-hydroxy-2-(5-nitro-2-Pyri-dylazo)-8-aminonaphthalene-3,6-disulfonic acid (5-NO2-PAH) and cationic surfactant to form 1:2 ionic association complex in a weakly basic medium (pH 9.44). The determination conditions and the mechanism were discussed. The method has been applied to the analysis of wastewater and moat water samples.

  19. Laser beam shaping for studying thermally induced damage

    CSIR Research Space (South Africa)

    Masina, BN

    2011-08-01

    Full Text Available for studying thermally induced damage Bathusile N. Masinaa, Richard Bodkinc, Bonex Mwakikungad and Andrew Forbesa,b?, aCSIR National Laser Centre, P. O. Box 395, Pretoria 0001, South Africa bSchool of Physics, University of KwaZulu-Natal, Private Bag X... from the blackbody at each wavelength, it is possible to determine the temperature of the blackbody or of the object by fitting the blackbody spectrum to the measured light. The advantage of using the blackbody emission is that there is no physical...

  20. Improvement of thermal management in the composite Yb:YAG/YAG thin-disk laser

    Science.gov (United States)

    Kuznetsov, I. I.; Mukhin, I. B.; Palashov, O. V.

    2016-04-01

    To improve the thermal management in the composite Yb:YAG/YAG thin-disk laser a new design of laser head is developed. Thermal-induced phase distortions, small signal gain and lasing in the upgraded laser head are investigated and compared with previously published results. A substantial decrease of the thermal lens optical power and phase aberrations and increase of the laser slope efficiency are observed. A continuous-wave laser with 440 W average power and 44% slope efficiency is constructed.

  1. Three-dimensional model on thermal response of skin subject to laser heating.

    Science.gov (United States)

    Shen, Wensheng; Zhang, Jun; Yang, Fuqian

    2005-04-01

    A three-dimensional (3D) multilayer model based on the skin physical structure is developed to investigate the transient thermal response of human skin subject to laser heating. The temperature distribution of the skin is modeled by the bioheat transfer equation, and the influence of laser heating is expressed as a source term where the strength of the source is a product of a Gaussian shaped incident irradiance, an exponentially shaped axial attenuation, and a time function. The water evaporation and diffusion is included in the model by adding two terms regarding the heat loss due to the evaporation and diffusion, where the rate of water evaporation is determined based on the theory of laminar boundary layer. Cryogen spray cooling (CSC) in laser therapy is studied, as well as its effect on the skin thermal response. The time-dependent equation is discretized using the finite difference method with the Crank-Nicholson scheme and the stability of the numerical method is analyzed. The large sparse linear system resulted from discretizing the governing partial differential equation is solved by a GMRES solver and the expected simulation results are obtained.

  2. Numerical simulation of thermal behavior during laser metal deposition shaping

    Institute of Scientific and Technical Information of China (English)

    LONG Ri-sheng; LIU Wei-jun; XING Fei; WANG Hua-bing

    2008-01-01

    Based on the element life and death theory of finite element analysis (FEA),a three-dimensional multi-track and multi-layer model for laser metal deposition shaping (LMDS) was developed with ANSYS parametric design language (APDL),and detailed numerical simulations of temperature and thermal stress were conducted.Among those simulations,long-edge parallel reciprocating scanning method was introduced.The distribution regularities of temperature,temperature gradient,Von Mise's effective stress,X-directional,Y-directional and Z-directional thermal stresses were studied.LMDS experiments were carried out with nickel-based superalloy using the same process parameters as those in simulation.The measured temperatures of molten pool are in accordance with the simulated results.The crack engendering and developing regularities of samples show good agreement with the simulation results.

  3. Study on Thermal Stability and Spectroscopic Properties of Nd3+ -Doped Phosphate Laser Glasses

    Institute of Scientific and Technical Information of China (English)

    Shi Qi; Lv Jingwen; Cheng Hong; Fu Xingguo; Sun Yu

    2004-01-01

    Fluorescence spectra, absorption spectra and thermal stability properties of Nd3 + -doped phosphate laser glasses were tested in this work. We calculated spectroscopic parameters of Nd3 + -doped phosphate laser glasses according to their absorption spectrum. Measuring and calculating linear thermal expansion coefficient, and analysising thermal stability of glasses show that this kind of Nd3 + -doped phosphate laser glasses has thermal expansion coefficient α = 38.75× 10 -7/℃ and optimal spectroscopic properties which extend application range of Nd +3-doped phosphate laser glasses.

  4. Thermal fixation: a central outcome of hyperthermic therapies (Invited Paper)

    Science.gov (United States)

    Coad, James E.

    2005-04-01

    Currently, several minimally invasive hyperthermic-based surgical technologies are available for the treatment of dysfunctional and neoplastic tissues in a variety of organ systems. These therapies involve a number of different modalities for delivering heat energy to the target tissue, including radiofrequency/microwave, conductive/convective, loop resection, and others. Despite differences in energy transfer and organ system treated, hyperthermic lesions often have a multiregional architecture with a central thermal fixation region, adjacent middle coagulative-type necrosis region, and outer transitional region of variable cell injury/death. The regional percentages of these components vary depending on the overall thermal history distribution across the lesion. The thermal-fixed region generally lacks a wound healing response, resists breakdown/tissue repair, and may elicit a localized foreign body-type reaction. The other two regions generally undergo wound healing/repair with scar formation. The features of thermal fixation are highlighted and explored through several histopathologic case vignettes.

  5. Hemodynamic Effect of Laser Therapy in Spontaneously Hypertensive Rats

    Directory of Open Access Journals (Sweden)

    Suely Tomimura

    2014-08-01

    Full Text Available Systemic arterial hypertension (SAH is considered to be the greatest risk factor for the development of neuro-cardiovascular pathologies, thus constituting a severe Public Health issue in the world. The Low-Level Laser Therapy (LLLT, or laser therapy, activates components of the cellular structure, therefore converting luminous energy into photochemical energy and leading to biophysical and biochemical reactions in the mitochondrial respiratory chain. The LLLT promotes cellular and tissue photobiomodulation by means of changes in metabolism, leading to molecular, cellular and systemic changes. The objective of this study was to analyze the action of low-level laser in the hemodynamic modulation of spontaneously hypertensive rats, in the long term. Animals (n = 16 were randomly divided into the Laser Group (n = 8, which received three weekly LLLT irradiations for seven weeks, and into the Sham Group (n = 8, which received three weekly simulations of laser for seven weeks, accounting for 21 applications in each group. After seven weeks, animals were cannulated by the implantation of a catheter in the left carotid artery. On the following day, the systemic arterial pressure was recorded. The Laser Group showed reduced levels of mean blood pressure, with statistically significant reduction (169 ± 4 mmHg* vs. 182 ± 4 mmHg from the Sham Group and reduced levels of diastolic pressure (143 ± 4 mmHg* vs. 157 ± 3 mmHg from the Sham Group, revealing a 13 and 14 mmHg decrease, respectively. Besides, there was a concomitant important decline in heart rate (312 ± 14 bpm vs. 361 ± 13 bpm from the Sham Group. Therefore, laser therapy was able to produce hemodynamic changes, thus reducing pressure levels in spontaneously hypertensive rats.

  6. Hemodynamic Effect of Laser Therapy in Spontaneously Hypertensive Rats

    Energy Technology Data Exchange (ETDEWEB)

    Tomimura, Suely, E-mail: suelytomimura@uol.com.br [Programa de Pós-Graduação em Biofotônica em Ciências da Saúde da Universidade Nove de Julho (UNINOVE) (Brazil); Silva, Bianca Passos Assumpção [Programa de Graduação e Pós-Graduação em Medicina da UNINOVE (Brazil); Sanches, Iris Callado [Laboratório de Fisiologia Translacional da UNINOVE (Brazil); Canal, Marina [Programa de Graduação e Pós-Graduação em Medicina da UNINOVE (Brazil); Consolim-Colombo, Fernanda [Programa de Graduação e Pós-Graduação em Medicina da UNINOVE (Brazil); Unidade de Hipertensão e Central Médica de Laser do Instituto do Coração - Hospital das Clinicas da Faculdade de Medicina da Universidade de São Paulo (InCor/HC-FMUSP), São Paulo, SP (Brazil); Conti, Felipe Fernandes; Angelis, Katia De [Laboratório de Fisiologia Translacional da UNINOVE (Brazil); Chavantes, Maria Cristina [Programa de Pós-Graduação em Biofotônica em Ciências da Saúde da Universidade Nove de Julho (UNINOVE) (Brazil); Programa de Graduação e Pós-Graduação em Medicina da UNINOVE (Brazil); Unidade de Hipertensão e Central Médica de Laser do Instituto do Coração - Hospital das Clinicas da Faculdade de Medicina da Universidade de São Paulo (InCor/HC-FMUSP), São Paulo, SP (Brazil)

    2014-08-15

    Systemic arterial hypertension (SAH) is considered to be the greatest risk factor for the development of neuro-cardiovascular pathologies, thus constituting a severe Public Health issue in the world. The Low-Level Laser Therapy (LLLT), or laser therapy, activates components of the cellular structure, therefore converting luminous energy into photochemical energy and leading to biophysical and biochemical reactions in the mitochondrial respiratory chain. The LLLT promotes cellular and tissue photobiomodulation by means of changes in metabolism, leading to molecular, cellular and systemic changes. The objective of this study was to analyze the action of low-level laser in the hemodynamic modulation of spontaneously hypertensive rats, in the long term. Animals (n = 16) were randomly divided into the Laser Group (n = 8), which received three weekly LLLT irradiations for seven weeks, and into the Sham Group (n = 8), which received three weekly simulations of laser for seven weeks, accounting for 21 applications in each group. After seven weeks, animals were cannulated by the implantation of a catheter in the left carotid artery. On the following day, the systemic arterial pressure was recorded. The Laser Group showed reduced levels of mean blood pressure, with statistically significant reduction (169 ± 4 mmHg* vs. 182 ± 4 mmHg from the Sham Group) and reduced levels of diastolic pressure (143 ± 4 mmHg* vs. 157 ± 3 mmHg from the Sham Group), revealing a 13 and 14 mmHg decrease, respectively. Besides, there was a concomitant important decline in heart rate (312 ± 14 bpm vs. 361 ± 13 bpm from the Sham Group). Therefore, laser therapy was able to produce hemodynamic changes, thus reducing pressure levels in spontaneously hypertensive rats.

  7. Low vision aid in exudative macular degeneration treated by photodynamic therapy and thermal laser photocoagulation%光动力治疗和热激光光凝治疗渗出性黄斑变性所致低视力

    Institute of Scientific and Technical Information of China (English)

    Montero JA; Ruiz-Moreno JM; Sanchez-de Castro MJ; Fabiani C

    2006-01-01

    · AIM: To determine the efficacy of low vision rehabilitation (LVR) in patients with age related macular degeneration (AMD) treated by photodynamic therapy (PDT) compared to those treated by thermal laser (TLP).examining the files of 42 patients (42 eyes) with AMD who had been treated either by TLP (Group 1) and PDT (Group 2). Once AMD was considered to be inactive they underwent visual rehabilitation in the LVR Unit in order to increase their ability for distant and near vision.received TLP. Average corrected visual acuity after laser therapy was 0.14 in Group 1, and 0.16 in Group 2. No statistically significant differences were found between both groups before and after laser therapy. Both groups showed improvement after LVR; however, statistically significant differences between both groups were found only for near vision.both PDT and TLP are associated to a decreased visual acuity after treatment, LVR may be more successful for near vision among patients treated by PDT%目的:比较观察光动力治疗(PDT)和热激光光凝(TLP)治疗对年龄相关性黄斑变性(AmD)患者低视力(LVR)的临床疗效.方法:对42例(42眼)AMD患者资料进行回顾性研究,其分别行TLP治疗(组1)或PDT治疗(组2).一旦确定AMD处于非活动期,患者在LVR部进行视力康复,以提高其远、近视功能.结果:18眼接受了PDT治疗,24眼进行TLP治疗.激光治疗后,组1患者的平均最佳矫正视力为0.14,组2平均为0.16.两组比较,视力于激光治疗前后都没有统计学差异;两组的LVR都有提高,但两组中只有近视力比较有统计学差异.结论:本研究结果表明,PDT和TLP治疗后患者的视力均有所下降,PDT治疗时,LVR患者近视力改善更为有效.

  8. Evaluation of the litcit software for thermal simulation of superficial lasers such as hair removal lasers

    Directory of Open Access Journals (Sweden)

    Shirkavand A

    2007-01-01

    Full Text Available Background and Objectives : In this study, we evaluate LITCIT software for its application as a thermal simulation software for superficial hair removal laser systems. Materials and Methods: Two articles were used as our references. Complete information regarding the tissues, such as optical/thermal properties and geometrical modeling and also the laser systems such as wavelength, spot size, pulse duration and fluence were extracted from these texts. Then, this information regarding the tissues and systems was entered into the LITCIT simulation software. Further, we ran the program and saved the results. Finally, we compared our results with the results in references and evaluated the. Results : Output results of the LITCIT show that they are consistent with the results of references that were calculated with a different thermal modeling. Such a small average error shows the accuracy of the software for simulation and calculating the temperature. Conclusions : This simulating software has a good ability to be used as a treatment planning software for superficial lasers. Thus, it can be used for the optimization of treatment parameters and protocols.

  9. Phototherapy, photodynamic therapy and lasers in the treatment of acne.

    Science.gov (United States)

    Degitz, Klaus

    2009-12-01

    Modern acne therapy uses anticomedogenic, antimicrobial, antiinflammatory,and antiandrogenic substances. As an additional approach in recent years, treatments have been developed based on the application of electromagnetic radiation. Visible light or infrared wave lengths are utilized by most techniques, including blue light lamps, intense pulsed light, photodynamic therapy and lasers. This review evaluates the various methods with regard to efficacy and their current role in the management of acne. Although UV radiation has been frequently used to treat acne, it is now regarded as obsolete due to the unfavorable risk-benefit ratio. Visible light, especially of blue wavelengths, appears to be suitable for the treatment of mild to moderate inflammatory acne. Photodynamic therapy is effective, but, due to considerable immediate side effects, it is best reserved for selected situations. Despite promising observations, intense pulsed light and lasers have to be evaluated in further studies, before they can be recommended.

  10. Ultrasound therapy applicators for controlled thermal modification of tissue

    Science.gov (United States)

    Burdette, E. Clif; Lichtenstiger, Carol; Rund, Laurie; Keralapura, Mallika; Gossett, Chad; Stahlhut, Randy; Neubauer, Paul; Komadina, Bruce; Williams, Emery; Alix, Chris; Jensen, Tor; Schook, Lawrence; Diederich, Chris J.

    2011-03-01

    Heat therapy has long been used for treatments in dermatology and sports medicine. The use of laser, RF, microwave, and more recently, ultrasound treatment, for psoriasis, collagen reformation, and skin tightening has gained considerable interest over the past several years. Numerous studies and commercial devices have demonstrated the efficacy of these methods for treatment of skin disorders. Despite these promising results, current systems remain highly dependent on operator skill, and cannot effectively treat effectively because there is little or no control of the size, shape, and depth of the target zone. These limitations make it extremely difficult to obtain consistent treatment results. The purpose of this study was to determine the feasibility for using acoustic energy for controlled dose delivery sufficient to produce collagen modification for the treatment of skin tissue in the dermal and sub-dermal layers. We designed and evaluated a curvilinear focused ultrasound device for treating skin disorders such as psoriasis, stimulation of wound healing, tightening of skin through shrinkage of existing collagen and stimulation of new collagen formation, and skin cancer. Design parameters were examined using acoustic pattern simulations and thermal modeling. Acute studies were performed in 201 freshly-excised samples of young porcine underbelly skin tissue and 56 in-vivo treatment areas in 60- 80 kg pigs. These were treated with ultrasound (9-11MHz) focused in the deep dermis. Dose distribution was analyzed and gross pathology assessed. Tissue shrinkage was measured based on fiducial markers and video image registration and analyzed using NIH Image-J software. Comparisons were made between RF and focused ultrasound for five energy ranges. In each experimental series, therapeutic dose levels (60degC) were attained at 2-5mm depth. Localized collagen changes ranged from 1-3% for RF versus 8-15% for focused ultrasound. Therapeutic ultrasound applied at high

  11. EFFECT OF LASER THERAPY IN INFLAMED TISSUE BY MEDICATIONS BASED ON IODOFORM LASER THERAPY IN INFLAMED TISSUE

    Directory of Open Access Journals (Sweden)

    Pablicia Juliana Santos Tomaz

    2013-01-01

    Full Text Available This study aimed to evaluate the inflammatory response of the subcutaneous tissue of twenty rats when the use of iodoform with different drugs or not associated with laser photobiomodulation. In the dorsum of rats were introduced into tubes containing: Iodoform and calcium hydroxide (Ca (OH2; Iodoform and Ca(OH2, associated with Laser; Iodoform and Otosporin; Iodoform and Otosporin, associated with Laser. The animals were euthanized eight and fifteen days after surgery, the parts were removed and processed in the laboratory with staining with Hematoxylin-Eosin (HE and Picrosirius Red. The statistical significances of the inflammatory infiltrate and quantification of collagen fibers were measured by ANOVA-Tukey test. The association between Ca (OH2 and iodoform with determined the best response in the host tissues. The low level laser therapy was effective in modulating the inflammatory response and deposit collagen fibers.

  12. Indications for laser therapy in diverse models of periodontitis

    Science.gov (United States)

    Kunin, Anatoly A.; Erina, Stanislava V.; Sokolova, Irina A.; Pankova, Svetlana N.; Ippolitov, Yu. A.; Lepechina, L. I.; Malinovskaya, L. A.; Chitrina, L. L.

    1996-11-01

    Parodontal diseases have an immunological pathogenic mechanism leading to various manifestations and can not be referred to as a common inflammation. The home and foreign research points at active and immunological reaction with the following distraction surrounding tissues of the tooth. Histochemical and biochemical examinations show metabolic disturbances of parodontal tissues. A total sample size of 604 people suffering from average height of chronic generalized parodontitis was examined in the survey. Immunological and histochemical tests were taken before and after a course of laser therapy with the use of helium-neon laser 'YAGODA', an inhibitory and stimulating dosage irradiations and anti-inflammatory dosage irradiations with infrared laser 'UZOR'. We selected a group of patients with the decreased local immunological status on the ground of immunological tests. Histochemical tests shaped the next group with the passive and active forms of parodontitis pathology. The tests data resulted in a method of laser therapy. The investigations confirm that the chronic generalized parodontitis has a shift in tissue immunity of the oral cavity and cell-bound metabolic disturbance of gum epithelium. It is expedient to use the anti-inflammatory dosage irradiations with infrared laser 'UZOR' to correct immunity, and in case of and active process to realize the DNA and RNA synthesis by means of increasing the irradiation with the apparatus 'YAGODA'. The irradiation decreases in case of a passive process.

  13. Investigation on nanoparticle distribution for thermal ablation of a tumour subjected to nanoparticle assisted thermal therapy.

    Science.gov (United States)

    Soni, Sanjeev; Tyagi, Himanshu; Taylor, Robert A; Kumar, Amod

    2014-07-01

    This study investigates the effect of the distribution of nanoparticles delivered to a skin tumour for the thermal ablation conditions attained during thermal therapy. Ultimate aim is to define a distribution of nanoparticles as well as a combination of other therapeutic parameters to attain thermal ablation temperatures (50-60 °C) within whole of the tumour region. Three different cases of nanoparticle distributions are analysed under controlled conditions for all other parameters viz. irradiation intensity and duration, and volume fraction of nanoparticles. Results show that distribution of nanoparticles into only the periphery of tumour resulted in desired thermal ablation temperature in whole of tumour. For the tumour size considered in this study, an irradiation intensity of 1.25 W/cm(2) for duration of 300 s and a nanoparticle volume fraction of 0.001% was optimal to attain a temperature of ≥53 °C within the whole tumour region. It is concluded that distribution of nanoparticles in peripheral region of tumour, along with a controlled combination of other parameters, seems favourable and provides a promising pathway for thermal ablation of a tumour subjected to nanoparticle assisted thermal therapy.

  14. Thermal conductivity of halite using a pulsed laser

    Energy Technology Data Exchange (ETDEWEB)

    Smith, D.D.

    1976-12-13

    A feasibility study of the experimental determination of thermal conductivities of salts (NaCl) and a steel casing material using a pulsed laser technique are presented. Optically transparent materials such as salt were effectively coated with an opaque layer of aluminum or silver to satisfy test boundary conditions. Thermal conductivities for the three specimens were obtained from the thermal diffusivity, heat capacity and density relationship. Based on measurements from room temperature to 923/sup 0/K, single crystal halite yielded values ranging from 6.5 to 1.5 W/m-K versus 5.5 to 1.2 W/m-K for Avery Island Bed Salt. AISI 106-Grade B steel gave values of 46 to 29 W/m-K. While these measurements may be no better than +- 10 percent, it is possible with appropriate equipment and technique to generate data of engineering quality, +- 5 percent error, provided adequate test specimens can be fabricated. Attributes of this technique include the generation of data very quickly which is more applicable to testing large numbers of specimens relative to steady-state methods. The use of penny-sized specimens can be a problem from the fabrication requirement, especially for friable and anisotropic geological materials. The quality of the data rests on the adherence of the experimental design to the mathematical model.

  15. Thermoelectric Device Fabrication Using Thermal Spray and Laser Micromachining

    Science.gov (United States)

    Tewolde, Mahder; Fu, Gaosheng; Hwang, David J.; Zuo, Lei; Sampath, Sanjay; Longtin, Jon P.

    2016-02-01

    Thermoelectric generators (TEGs) are solid-state devices that convert heat directly into electricity. They are used in many engineering applications such as vehicle and industrial waste-heat recovery systems to provide electrical power, improve operating efficiency and reduce costs. State-of-art TEG manufacturing is based on prefabricated materials and a labor-intensive process involving soldering, epoxy bonding, and mechanical clamping for assembly. This reduces their durability and raises costs. Additive manufacturing technologies, such as thermal spray, present opportunities to overcome these challenges. In this work, TEGs have been fabricated for the first time using thermal spray technology and laser micromachining. The TEGs are fabricated directly onto engineering component surfaces. First, current fabrication techniques of TEGs are presented. Next, the steps required to fabricate a thermal spray-based TEG module, including the formation of the metallic interconnect layers and the thermoelectric legs are presented. A technique for bridging the air gap between two adjacent thermoelectric elements for the top layer using a sacrificial filler material is also demonstrated. A flat 50.8 mm × 50.8 mm TEG module is fabricated using this method and its performance is experimentally characterized and found to be in agreement with expected values of open-circuit voltage based on the materials used.

  16. Reducing Thermal Effect in End-Diode-Pumped Laser Crystal by Using a Novel Resonator

    Institute of Scientific and Technical Information of China (English)

    YAO Ai-Yun; HOU Wei; LI Hui-Qing; BI Yong; LIN Xue-Chun; GENG Ai-Cong; KONG Yu-Peng; CUI Da-Fu; XU Zu-Yan

    2005-01-01

    @@ We report a new way, i.e. double-end-pumping, to extend the stability range of a laser resonator, in advantage of making the thermal loading be effectively divided between the ends of the laser crystal to reduce the thermal effect, thus to extend the stability range.

  17. Time-dependent analytical thermal model to investigate thermally induced stresses in quasi-CW-pumped laser rods

    CSIR Research Space (South Africa)

    Bernhardi, EH

    2008-01-01

    Full Text Available One of the main problems that limit the power scaling of diode-end-pumped solid-state lasers is the generation of heat inside the laser gain medium which can ultimately cause fracture. In this paper a time-dependent analytical thermal model...

  18. The intensity distribution and thermal stability of InnoSlab laser

    Institute of Scientific and Technical Information of China (English)

    Ning Wang; Peng Shi; Yutian Lu

    2005-01-01

    Partially end-pumped slab laser is an innovative solid state laser, namely InnoSlab. Combining the hybrid resonator with partially end-pumping, the output power can be scaled with high beam quality. In this paper, the output intensity distributions are simulated by coordinate transformation fast Fourier transform(FFT) algorithm, comparing the thermal lens influence. As the simulated curves showed, the output mode is still good when the thermal lens effect is strong, indicatingthe good thermal stability of InnoSlab laser.Such a new kind of laser can be designed and optimized on the base of this simulation.

  19. Study on the effect of thermal property of metals in ultrasonic-assisted laser machining

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hu Seung; Kim, Gun Woo; Park, Jong Eun [Dept. of Mechanical Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Cho, Sung Hak; Yang, Min Yang; Park, Jong Kweon [Korea Institute of Machinery and Materials, Deajeon (Korea, Republic of)

    2015-08-15

    The laser machining process has been proposed as an advanced process for the selective fabrication of electrodes without a mask. In this study, we adapt laser machining to metals that have different thermal properties. Based on the results, the metals exhibit a different surface morphology, heat-affected zone (HAZ), and a recast layer around the machined surface according to their thermal conductivity, boiling point, and thermal diffusivity. Then, we apply ultrasonic-assisted laser machining to remove the recast layer. The ultrasonic-assisted laser machining exhibits a better surface quality in metals with higher diffusivity than those having lower diffusivity.

  20. Endoscopic laser therapy of erosive-ulcerous and inflammatory damages of patients in oncological hospital

    Science.gov (United States)

    Efimov, Oleg N.; Kuvshinov, Yu. P.; Poddubny, Boris K.; Kartasheva, E. O.; Ungiadze, G. V.; Ponomarev, Igor V.; Mazurov, S. T.

    1996-01-01

    The results of laser therapy present in 374 patients with erosive-ulcerous and inflammatory damages of respiratory organs and of gastro-intestinal tract after oncological operations. Two types of laser namely endoscopic laser on the basis of He-Ne and Cu laser were used as sources of radiation. It was shown high therapeutic effectiveness of laser therapy. This method may be recommended for the above-mentioned category of the patients.

  1. Feasibility of using laser ion accelerators in proton therapy

    CERN Document Server

    Bulanov, S V

    2002-01-01

    The feasibility of using the laser plasma as a source of the high-energy ions for the proton radiation therapy is discussed. The proposal is based on the recent inventions of the effective ions acceleration in the experiments and through numerical modeling of the powerful laser radiation interaction with the gaseous and solid state targets. The principal peculiarity of the dependence of the protons energy losses in the tissues (the Bragg peak of losses) facilities the solution of one of the most important problems of the radiation therapy, which consists in realizing the tumor irradiation by sufficiently high and homogeneous dose with simultaneous minimization of the irradiation level, relative to the healthy and neighbouring tissues and organs

  2. Laser-high-speed-DSC: Process-oriented Thermal Analysis of PA 12 in Selective Laser Sintering

    Science.gov (United States)

    Lanzl, Lydia; Wudy, Katrin; Drexler, Maximilian; Drummer, Dietmar

    In the Selective Laser Sintering process very high heating rates occur due to the melting of the material by a laser. Extreme scanning rates could not be measured by conventional thermal analysis methods, since typical heating rates for DSC (differential scanning calorimetry) are between 5-20K min-1. By using a Laser-High-Speed-DSC, a self-developed combination of a Flash-DSC and a fitted laser head, the sample is directly heated by a CO2 laser like in the SLS process. These experiments allow a process-oriented thermal analyzation of the material. In this paper, the set-up and function of this new measuring method is introduced. Furthermore, the reliability of the measurements is evaluated by statistical design of experiment methods. By using this new measuring method, the time-dependent melting behavior of the polymer can be analyzed. Moreover, sample temperatures and heating rates dependent on laser exposure times can be quantified.

  3. Laser cutting sandwich structure glass-silicon-glass wafer with laser induced thermal-crack propagation

    Science.gov (United States)

    Cai, Yecheng; Wang, Maolu; Zhang, Hongzhi; Yang, Lijun; Fu, Xihong; Wang, Yang

    2017-08-01

    Silicon-glass devices are widely used in IC industry, MEMS and solar energy system because of their reliability and simplicity of the manufacturing process. With the trend toward the wafer level chip scale package (WLCSP) technology, the suitable dicing method of silicon-glass bonded structure wafer has become necessary. In this paper, a combined experimental and computational approach is undertaken to investigate the feasibility of cutting the sandwich structure glass-silicon-glass (SGS) wafer with laser induced thermal-crack propagation (LITP) method. A 1064 nm semiconductor laser cutting system with double laser beams which could simultaneously irradiate on the top and bottom of the sandwich structure wafer has been designed. A mathematical model for describing the physical process of the interaction between laser and SGS wafer, which consists of two surface heating sources and two volumetric heating sources, has been established. The temperature stress distribution are simulated by using finite element method (FEM) analysis software ABAQUS. The crack propagation process is analyzed by using the J-integral method. In the FEM model, a stationary planar crack is embedded in the wafer and the J-integral values around the crack front edge are determined using the FEM. A verification experiment under typical parameters is conducted and the crack propagation profile on the fracture surface is examined by the optical microscope and explained from the stress distribution and J-integral value.

  4. Simulation study on thermal effect of long pulse laser interaction with CFRP material

    Science.gov (United States)

    Ma, Yao; Jin, Guangyong; Yuan, Boshi

    2016-10-01

    Laser machining is one of most widely used technologies nowadays and becoming a hot industry as well. At the same time, many kinds of carbon fiber material have been used in different area, such as sports products, transportation, microelectronic industry and so on. Moreover, there is lack of the combination research on the laser interaction with Carbon Fiber Reinforced Polymer (CFRP) material with simulation method. In this paper, the temperature status of long pulse laser interaction with CFRP will be simulated and discussed. Firstly, a laser thermal damage model has been built considering the heat conduction theory and thermal-elasto-plastic theory. Then using COMSOL Multiphysics software to build the geometric model and to simulate the mathematic results. Secondly, the functions of long pulse laser interaction with CFRP has been introduced. Material surface temperature increased by time during the laser irradiating time and the increasing speed is faster when the laser fluence is higher. Furthermore, the peak temperature of the center of material surface is increasing by enhanced the laser fluence when the pulse length is a constant value. In this condition, both the ablation depth and the Heat Affected Zone(HAZ) is larger when increased laser fluence. When keep the laser fluence as a constant value, the laser with shorter pulse length is more easier to make the CFRP to the vaporization material. Meanwhile, the HAZ is becoming larger when the pulse length is longer, and the thermal effect depth is as the same trend as the HAZ. As a result, when long pulse laser interaction with CFRP material, the thermal effect is the significant value to analysis the process, which is mostly effect by laser fluence and pulse length. For laser machining in different industries, the laser parameter choose should be different. The shorter pulse length laser is suitable for the laser machining which requires high accuracy, and the longer one is better for the deeper or larger

  5. Laser Doppler flowmeter and standardized thermal test in normals and Raynaud's phenomenon.

    Science.gov (United States)

    Boccalon, H J; Marguery, M C; Ginestet, M C; Puel, P F

    1987-01-01

    The diagnosis of Raynaud's phenomenon alone requires clinical investigations. To determine the stage of the disease, its etiology and pathophysiology, it seems desirable to perform noninvasive tests. Conclusions regarding control o the skin or muscle components of hand blood flow rely on evidence from separate measurements of skin or muscle blood flow. We described a standardized thermal provocation test, then respiratory maneuvers and pharmacological trials, to stimulate the microcirculatory control. The total cutaneous blood flow was continuously registered using a laser Doppler flowmeter. We conducted a prospective study on 100 subjects: 21 normal, 22 primary Raynaud's phenomenon (PRP), 26 secondary (SRP), 31 various microcirculatory diseases. The basal blood flow was lower in cases of severe SRP and acrocyanosis. In comparison with normals, RP cases present a less noticeable reaction to cold. Mild SRPs are more sensitive to cold and do not recover during warming up. Severe RPs are less sensitive to cold as they have a lower basal blood flow. Acrocyanosis cases are not sensitive to thermal variations. Post ischemic reactive hyperemia leads to a constant peak flow. Pharmacological assays were performed (nitroglycerine, Nifedipine) during permanent control of skin and muscle blood flow. Laser Doppler and provocation tests have no etiologic value in a Raynaud's phenomenon investigation; this methodology tries to elucidate the pathophysiology, the prognosis and the therapy of Raynaud's phenomenon.

  6. Low-power laser therapy for carpal tunnel syndrome: effective optical power

    OpenAIRE

    Yan Chen; Cheng-qiang Zhao; Gang Ye; Can-dong Liu; Wen-dong Xu

    2016-01-01

    Low-power laser therapy has been used for the non-surgical treatment of mild to moderate carpal tunnel syndrome, although its efficacy has been a long-standing controversy. The laser parameters in low-power laser therapy are closely related to the laser effect on human tissue. To evaluate the efficacy of low-power laser therapy, laser parameters should be accurately measured and controlled, which has been ignored in previous clinical trials. Here, we report the measurement of the effective op...

  7. The Combination of Laser Therapy and Metal Nanoparticles in Cancer Treatment Originated From Epithelial Tissues: A Literature Review

    Science.gov (United States)

    Fekrazad, Reza; Naghdi, Nafiseh; Nokhbatolfoghahaei, Hanieh; Bagheri, Hossein

    2016-01-01

    Several methods have been employed for cancer treatment including surgery, chemotherapy and radiation therapy. Today, recent advances in medical science and development of new technologies, have led to the introduction of new methods such as hormone therapy, Photodynamic therapy (PDT), treatments using nanoparticles and eventually combinations of lasers and nanoparticles. The unique features of LASERs such as photo-thermal properties and the particular characteristics of nanoparticles, given their extremely small size, may provide an interesting combined therapeutic effect. The purpose of this study was to review the simultaneous application of lasers and metal nanoparticles for the treatment of cancers with epithelial origin. A comprehensive search in electronic sources including PubMed, Google Scholar and Science Direct was carried out between 2000 and 2013. Among the initial 400 articles, 250 articles applied nanoparticles and lasers in combination, in which more than 50 articles covered the treatment of cancer with epithelial origin. In the future, the combination of laser and nanoparticles may be used as a new or an alternative method for cancer therapy or diagnosis. Obviously, to exclude the effect of laser’s wavelength and nanoparticle’s properties more animal studies and clinical trials are required as a lack of perfect studies PMID:27330701

  8. Thermal Conductivity of Advanced Ceramic Thermal Barrier Coatings Determined by a Steady-state Laser Heat-flux Approach

    Science.gov (United States)

    Zhu, Dong-Ming; Miller, Robert A.

    2004-01-01

    The development of low conductivity and high temperature capable thermal barrier coatings requires advanced testing techniques that can accurately and effectively evaluate coating thermal conductivity under future high-performance and low-emission engine heat-flux conditions. In this paper, a unique steady-state CO2 laser (wavelength 10.6 microns) heat-flux approach is described for determining the thermal conductivity and conductivity deduced cyclic durability of ceramic thermal and environmental barrier coating systems at very high temperatures (up to 1700 C) under large thermal gradients. The thermal conductivity behavior of advanced thermal and environmental barrier coatings for metallic and Si-based ceramic matrix composite (CMC) component applications has also been investigated using the laser conductivity approach. The relationships between the lattice and radiation conductivities as a function of heat flux and thermal gradient at high temperatures have been examined for the ceramic coating systems. The steady-state laser heat-flux conductivity approach has been demonstrated as a viable means for the development and life prediction of advanced thermal barrier coatings for future turbine engine applications.

  9. [Thermal therapy for the management of cardiovascular pathology].

    Science.gov (United States)

    Persiianova-Dubrova, A L; Badalov, N G

    2013-01-01

    This paper reports the results of analysis of the study on the effect of thermal therapy in the patients presenting with cardiovascular diseases including coronary heart disease, chronic heart failure, and myocardial infarction. It is shown that the correct application of the "Finnish" and infrared sauna taking into consideration specific clinical characteristics of the disease in question and with strict compliance to the relevant methodological recommendations can produce beneficial effects in the form of the improved endothelial function, reduced heart rate variability and oxidative stress as well as enhanced physical performance. It is concluded that full-scale studies in accordance with the principles of evidence-based medicine are needed to further improve the effectiveness of the thermal treatment of cardiovascular diseases and the reliability of the data obtained.

  10. Regulation of miRNA Expression by Low-Level Laser Therapy (LLLT and Photodynamic Therapy (PDT

    Directory of Open Access Journals (Sweden)

    Miya Ishihara

    2013-06-01

    Full Text Available Applications of laser therapy, including low-level laser therapy (LLLT, phototherapy and photodynamic therapy (PDT, have been proven to be beneficial and relatively less invasive therapeutic modalities for numerous diseases and disease conditions. Using specific types of laser irradiation, specific cellular activities can be induced. Because multiple cellular signaling cascades are simultaneously activated in cells exposed to lasers, understanding the molecular responses within cells will aid in the development of laser therapies. In order to understand in detail the molecular mechanisms of LLLT and PDT-related responses, it will be useful to characterize the specific expression of miRNAs and proteins. Such analyses will provide an important source for new applications of laser therapy, as well as for the development of individualized treatments. Although several miRNAs should be up- or down-regulated upon stimulation by LLLT, phototherapy and PDT, very few published studies address the effect of laser therapy on miRNA expression. In this review, we focus on LLLT, phototherapy and PDT as representative laser therapies and discuss the effects of these therapies on miRNA expression.

  11. Shielding design for a laser-accelerated proton therapy system.

    Science.gov (United States)

    Fan, J; Luo, W; Fourkal, E; Lin, T; Li, J; Veltchev, I; Ma, C-M

    2007-07-07

    In this paper, we present the shielding analysis to determine the necessary neutron and photon shielding for a laser-accelerated proton therapy system. Laser-accelerated protons coming out of a solid high-density target have broad energy and angular spectra leading to dose distributions that cannot be directly used for therapeutic applications. A special particle selection and collimation device is needed to generate desired proton beams for energy- and intensity-modulated proton therapy. A great number of unwanted protons and even more electrons as a side-product of laser acceleration have to be stopped by collimation devices and shielding walls, posing a challenge in radiation shielding. Parameters of primary particles resulting from the laser-target interaction have been investigated by particle-in-cell simulations, which predicted energy spectra with 300 MeV maximum energy for protons and 270 MeV for electrons at a laser intensity of 2 x 10(21) W cm(-2). Monte Carlo simulations using FLUKA have been performed to design the collimators and shielding walls inside the treatment gantry, which consist of stainless steel, tungsten, polyethylene and lead. A composite primary collimator was designed to effectively reduce high-energy neutron production since their highly penetrating nature makes shielding very difficult. The necessary shielding for the treatment gantry was carefully studied to meet the criteria of head leakage shield neutrons and an outer layer of lead was used to reduce photon dose from neutron capture and electron bremsstrahlung. It is shown that the two-layer shielding design with 10-12 cm thick polyethylene and 4 cm thick lead can effectively absorb the unwanted particles to meet the shielding requirements.

  12. Shielding design for a laser-accelerated proton therapy system

    Science.gov (United States)

    Fan, J.; Luo, W.; Fourkal, E.; Lin, T.; Li, J.; Veltchev, I.; Ma, C.-M.

    2007-07-01

    In this paper, we present the shielding analysis to determine the necessary neutron and photon shielding for a laser-accelerated proton therapy system. Laser-accelerated protons coming out of a solid high-density target have broad energy and angular spectra leading to dose distributions that cannot be directly used for therapeutic applications. A special particle selection and collimation device is needed to generate desired proton beams for energy- and intensity-modulated proton therapy. A great number of unwanted protons and even more electrons as a side-product of laser acceleration have to be stopped by collimation devices and shielding walls, posing a challenge in radiation shielding. Parameters of primary particles resulting from the laser-target interaction have been investigated by particle-in-cell simulations, which predicted energy spectra with 300 MeV maximum energy for protons and 270 MeV for electrons at a laser intensity of 2 × 1021 W cm-2. Monte Carlo simulations using FLUKA have been performed to design the collimators and shielding walls inside the treatment gantry, which consist of stainless steel, tungsten, polyethylene and lead. A composite primary collimator was designed to effectively reduce high-energy neutron production since their highly penetrating nature makes shielding very difficult. The necessary shielding for the treatment gantry was carefully studied to meet the criteria of head leakage shield neutrons and an outer layer of lead was used to reduce photon dose from neutron capture and electron bremsstrahlung. It is shown that the two-layer shielding design with 10-12 cm thick polyethylene and 4 cm thick lead can effectively absorb the unwanted particles to meet the shielding requirements.

  13. Percutaneous laser-assisted thermal coronary angioplasty in native coronary arteries and saphenous vein grafts: initial results and angiographic follow-up.

    Science.gov (United States)

    Linnemeier, T J; Rothbaum, D A; Cumberland, D C; Landin, R J; Hodes, Z I; Ball, M W

    1990-01-01

    Percutaneous laser-assisted thermal coronary angioplasty was attempted in 29 vessels (27 patients): 10 left anterior descending, 2 left circumflex and 17 mid-shaft (non-anastomotic) saphenous vein grafts. Argon or YAG laser thermal energy was applied via a 1.3, 1.6 or 1.9 mm metal capped probe followed by conventional balloon angioplasty in 27 vessels and sole thermal laser therapy in two vessels. The laser probe successfully crossed 83% (24/29) of vessels and subsequent balloon dilatation increased the success rate to 93% (25/27). Perforation occurred in a vein graft resulting in one in-hospital death post repeat emergency coronary artery bypass graft surgery. Angiographic follow-up was obtained in 85% (24/28) of vessels. Angiographic restenosis ( greater than 50% reduction in lumen diameter) occurred in 27% (3/11) of native coronary arteries and 62% (8/13) of saphenous vein grafts. Therefore, despite high initial success rates, the application of laser thermal energy with small laser probes relative to vessel size, followed by conventional balloon angioplasty, does not appear to alter restenosis. Further evaluation of coronary laser systems should be continued only with catheters that are capable of creating channels closer to the size of the vessel treated.

  14. Evaluation of the Effect of Low Level Laser Therapy Toothbrush in Treatment of Dentin Hypersensitivity

    OpenAIRE

    Yaghini, Jaber; Mogharehabed, Ahmad; Safavi, Nassimeh; Mohamadi, Mehrnush; Ashtiju, Fahime

    2015-01-01

    Introduction: Dentin hypersensitivity is one of the most common complications that affect patients after periodontal therapy. Recently low level laser therapy has been introduced as a new treatment modality and has produced beneficial results. The purpose of this study is to evaluate the effect of low level laser therapy toothbrushes in reduction of dentin hypersensitivity.

  15. The combination treatment using CO₂ laser and photodynamic therapy for HIV seropositive men with intraanal warts.

    Science.gov (United States)

    Xu, Juan; Xiang, Li; Chen, Jiayuan; He, Qin; Li, Qing; Li, Jing; Wang, Jing

    2013-05-01

    We evaluate the effectiveness of combination treatment using photodynamic therapy after carbon dioxide laser in preventing the recurrence of condylomata acuminata for intraanal warts in HIV positive homosexual men. A retrospective survey of 41 patients referred to the STD clinic of the Fourth People's Hospital of Shenzhen for the treatment of intraanal warts among HIV positive homosexual men between Janurary 2009 and September 2011. The patients who accepted CO₂ laser monotherapy for the same diagnosis were used as the comparison group. After the confirmation of the diagnosis of HIV infection and intraanal warts, the patients were treated with the combination treatment using PDT with 5-ALA thermal gel immediately after CO₂ laser ablation of the warts. PDT was performed with irradiation of 100 J/cm² at an irradiance of 100-150 mW/cm² with a semiconductor laser, wavelength 635 nm. PDT therapy was repeated twice with 2 weekly intervals. Follow up examinations including an anoscopy every 4 weeks after the latest PDT. After 3 cycles of PDT treatments, 39 cases of anoscopy examination showed no new or recurrent lesions. At the end of the sixth months, recurrence occurred in 12(29%) cases. HPV 11 was present in 6 (50%) of these recurrences. HPV 6/11 or 16/18 remains positive in 19 cases (46.3%) and HPV negative in 22 cases. The combination treatment with CO₂ laser and PDT is much more effective in reducing the treatment cycles and the time intervals of the whole treatment for intraanal warts in HIV infected people. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Treating cognitive impairment with transcranial low level laser therapy.

    Science.gov (United States)

    de la Torre, Jack C

    2017-03-01

    This report examines the potential of low level laser therapy (LLLT) to alter brain cell function and neurometabolic pathways using red or near infrared (NIR) wavelengths transcranially for the prevention and treatment of cognitive impairment. Although laser therapy on human tissue has been used for a number of medical conditions since the late 1960s, it is only recently that several clinical studies have shown its value in raising neurometabolic energy levels that can improve cerebral hemodynamics and cognitive abilities in humans. The rationale for this approach, as indicated in this report, is supported by growing evidence that neurodegenerative damage and cognitive impairment during advanced aging is accelerated or triggered by a neuronal energy crisis generated by brain hypoperfusion. We have previously proposed that chronic brain hypoperfusion in the elderly can worsen in the presence of one or more vascular risk factors, including hypertension, cardiac disease, atherosclerosis and diabetes type 2. Although many unanswered questions remain, boosting neurometabolic activity through non-invasive transcranial laser biostimulation of neuronal mitochondria may be a valuable tool in preventing or delaying age-related cognitive decline that can lead to dementia, including its two major subtypes, Alzheimer's and vascular dementia. The technology to achieve significant improvement of cognitive dysfunction using LLLT or variations of this technique is moving fast and may signal a new chapter in the treatment and prevention of neurocognitive disorders. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Effects of a laser acupuncture therapy on treating pain

    Science.gov (United States)

    Wong, Wai-on; Xiao, Shaojun; Ip, Wing-Yuk; Guo, Xia

    2001-10-01

    Laser acupuncture (LA) has been utilized as a combined approach of Chinese traditional acupuncture and low-level laser therapy since its emergence in 1973. Its mechanisms are not well understood and the standardization of clinical protocols has not been established. In this study, we used a diode laser to irradiate on four acupuncture points for normal subjects to investigate the effect of LA. For each point, the irradiation lasted for three minutes. The median nerve conduction velocity was measured within a 30 minutes interval at day 1, day 5, and day 10 respectively. Patients with chronic carpal tunnel syndrome (CTS) were given LA therapy for three stages at most with a one-week interval between two stages. Treatment outcome measurements included patients' subjective feedback (McGill pain questionnaire, VAS) and objective measurements (physical examination, kinesiological properties and NCSs). It was a randomized single-blind controlled trial. For normal subjects, motor nerve fiber was sensitive to LA and the motor conduction velocity was decreased very significantly (p < 0.001). Besides, it was found that LA resulted that sensory nerve conduction velocity was decreased significantly when it was measured 30 minutes after the subject had received LA application. For CTS patients, the outcomes except pinch test indicated that LA could improve patient's conduction. These results suggested that LA could cause the change of nerve conduction.

  18. Advances in endonasal low intensity laser irradiation therapy

    Science.gov (United States)

    Jiao, Jian-Ling; Liu, Timon C.; Liu, Jiang; Cui, Li-Ping; Liu, Song-hao

    2005-07-01

    Endonasal low intensity laser therapy (ELILT) began in China in 1998. Now in China it is widely applied to treat hyperlipidemia and brain diseases such as Alzheimer's disease, Parkinson's disease, insomnia, poststroke depression, intractable headache, ache in head or face, cerebral thrombosis, acute ischemic cerebrovascular disease, migraine, brain lesion and mild cognitive impairment. There are four pathways mediating EILILT, Yangming channel, autonomic nervous systems and blood cells. Two unhealth acupoints of Yangming channal inside nose might mediate the one as is low intensity laser acupuncture. Unbalance autonomic nervous systems might be modulated. Blood cells might mediate the one as is intravascular low intensity laser therapy. These three pathways are integrated in ELILT so that serum amyloid β protein, malformation rate of erythrocyte, CCK-8, the level of viscosity at lower shear rates and hematocrit, or serum lipid might decrease, and melanin production/SOD activity or β endorphin might increase after ELILT treatment. These results indicate ELILT might work, but it need to be verified by randomized placebo-controlled trial.

  19. Effect of interstitial low level laser therapy on tibial defect

    Science.gov (United States)

    Lee, Sangyeob; Ha, Myungjin; Hwang, Donghyun; Yu, Sungkon; Jang, Seulki; Park, Jihoon; Radfar, Edalat; Kim, Hansung; Jung, Byungjo

    2016-03-01

    Tibial defect is very common musculoskeletal disorder which makes patient painful and uncomfortable. Many studies about bone regeneration tried to figure out fast bone healing on early phase. It is already known that low level laser therapy (LLLT) is very convenient and good for beginning of bone disorder. However, light scattering and absorption obstruct musculoskeletal therapy which need optimal photon energy delivery. This study has used an interstitial laser probe (ILP) to overcome the limitations of light penetration depth and scattering. Animals (mouse, C57BL/6) were divided into three groups: laser treated test group 1 (660 nm; power 10 mW; total energy 5 J) and test group 2 (660 nm; power 20 mW; total energy 10 J); and untreated control group. All animals were taken surgical operation to make tibial defect on right crest of tibia. The test groups were treated every 48 hours with ILP. Bone volume and X-ray attenuation coefficient were measured on 0, 14th and 28th day with u-CT after treatment and were used to evaluate effect of LLLT. Results show that bone volume of test groups has been improved more than control group. X-ray attenuation coefficients of each groups have slightly different. The results suggest that LLLT combined with ILP may affect on early phase of bone regeneration and may be used in various musculoskeletal disease in deep tissue layer.

  20. [Magneto-laser therapy of chronic gastritis in children and adolescents].

    Science.gov (United States)

    Zviagin, A A; Nikolaenko, E A

    2008-01-01

    The efficiency of transcutaneous magneto-laser treatment as a component of combined therapy of chronic gastritis in children and adolescents (aged 5-17 years) was compared with that of pharmacotherapy and low-intensity laser therapy. The patients were allocated to three groups of 25 persons each. Patients of group 1 were given only drug therapy, those in group 2 were treated with pharmaceuticals and low-intensity laser therapy. The patients comprising group 3 were subjected to the action of magneto-laser radiation. Magneto-laser therapy was shown to result in a significantly more expressed improvement of clinical and morphological characteristics of the patients compared with pharmacotherapy alone. There was no significant difference between effects of magneto-laser and low-intensity laser radiation.

  1. Laser cutting silicon-glass double layer wafer with laser induced thermal-crack propagation

    Science.gov (United States)

    Cai, Yecheng; Yang, Lijun; Zhang, Hongzhi; Wang, Yang

    2016-07-01

    This study was aimed at introducing the laser induced thermal-crack propagation (LITP) technology to solve the silicon-glass double layer wafer dicing problems in the packaging procedure of silicon-glass device packaged by WLCSP technology, investigating the feasibility of this idea, and studying the crack propagation process of LITP cutting double layer wafer. In this paper, the physical process of the 1064 nm laser beam interact with the double layer wafer during the cutting process was studied theoretically. A mathematical model consists the volumetric heating source and the surface heating source has been established. The temperature and stress distribution was simulated by using finite element method (FEM) analysis software ABAQUS. The extended finite element method (XFEM) was added to the simulation as the supplementary features to simulate the crack propagation process and the crack propagation profile. The silicon-glass double layer wafer cutting verification experiment under typical parameters was conducted by using the 1064 nm semiconductor laser. The crack propagation profile on the fracture surface was examined by optical microscope and explained from the stress distribution and XFEM status. It was concluded that the quality of the finished fracture surface has been greatly improved, and the experiment results were well supported by the numerical simulation results.

  2. Thermal Analysis of Heat-Assisted Magnetic Recording Optical Head with Laser Diode on Slider

    Science.gov (United States)

    Xu, Baoxi; Chia, Cheow Wee; Zhang, Qide; Teck Toh, Yeow; An, Chengwu; Vienne, Guillaume

    2011-09-01

    For the optical head used in heat-assisted magnetic recording (HAMR), mounting a laser diode chip on the slider offers a more integrated, compact, and stable design. However, the heat generated by the laser diode will cause the head temperature to increase, which may decrease the laser output power and change the slider flying status. In this paper, the thermal analysis of the HAMR head including the laser diode and a transducer is conducted. The effects of the laser diode power, the power absorbed by the transducer, boundary thermal resistance between the laser diode chip and the slider substrate, and slider fly speed and fly height on the laser temperature increase, the transducer temperature increase, and the air-bearing surface temperature distribution are studied. The deformation of the air-bearing surface caused by its temperature change is also analyzed.

  3. Thermal conductivity measurements of laser crystals by infrared thermography. Application to Nd:doped crystals.

    Science.gov (United States)

    Didierjean, Julien; Herault, Emilie; Balembois, François; Georges, Patrick

    2008-06-09

    We present a thermal conductivity measurement method for laser crystals based on thermal mapping of the crystal face by an infrared camera. Those measurements are performed under end-pumping of the laser crystal and during laser operation. The calculation of the fraction of pump power converted into heat is therefore simplified, and it is possible to link easily the temperature in the crystal to the thermal conductivity. We demonstrate the efficiency of this measurement method with a Nd:YAG crystal, before using it to compare Nd:YVO(4) and Nd:GdVO(4) crystals.

  4. Laser therapy in wound healing associated with diabetes mellitus - Review*

    Science.gov (United States)

    de Sousa, Raquel Gomes; Batista, Keila de Nazaré Madureira

    2016-01-01

    The article discusses the results of a literature review on the application of low intensity laser therapy on the healing of wounds associated diabetes mellitus in the last 10 years. Objective To determine the most effective parameter in healing wounds related to diabetes mellitus, as well as the most widely used type of laser. Methodology consisted of bibliographic searching the databases Bireme, SciELO, PubMed/Medline and Lilacs by using the keywords related to the topic. Were selected from these keywords, papers discussing the use of laser on wounds associated with diabetes, published in the period 2005-2014, in Portuguese or English. Results After analyzing the research, 12 studies consistent with the theme were selected. Conclusion Based on this review, the studies that showed more satisfactory results in healing diabetic wounds were those who applied energy densities in the range of 3-5 J/cm2, power densities equal to or below 0.2 W/cm2 and continuous emission. The He-Ne laser with a wavelength of 632.8 nm was used more often. PMID:27579745

  5. Nd: YAG laser therapy of rectosigmoid bleeding due to radiation injury

    Energy Technology Data Exchange (ETDEWEB)

    Leuchter, R.S.; Petrilli, E.S.; Dwyer, R.M.; Hacker, N.F.; Castaldo, T.W.; Lagasse, L.D.

    1982-06-01

    The Nd:YAG laser was used to treat a patient bleeding from the rectosigmoid as a result of radiation injury related to therapy for cervical carcinoma. Successful laser therapy was performed after a diverting colostomy failed to control persistent bleeding. Further surgical procedures were not required. Characteristics of Nd:YAG laser as compared with those of the carbon dioxide and argon lasers are considered.

  6. Biostimulative laser therapy in difficult dentition of a lower wisdom tooth

    Science.gov (United States)

    Grzesiak-Janas, Grazyna

    1996-03-01

    In a group of 66 patients treated for difficult dentition of the lower wisdom tooth, 33 were subjected to biostimulative laser therapy. In this group 20 persons were treated conservatively together with laser therapy and 13 underwent surgical treatment together with exposure to laser irradiation. During the treatment a positive influence of the laser was found, i.e. a decrease in pain, edema, and trismus.

  7. Laser-Time Interaction XII: Photochemical, Photothermal, and Photomechanical

    Science.gov (United States)

    Duncan, Donald D.; Jacques, Steven L.; Johnson, Peter C.

    2001-01-01

    This proceedings contains papers on the following topics: photodynamic therapy, immunotherapy, pulsed laser effects, polarized light interactions, photochemical interactions, occular laser effects,thermal interactions, laser shaping of cartilage.

  8. Near-IR Imaging of Thermal Changes in Enamel during Laser Ablation.

    Science.gov (United States)

    Maung, Linn H; Lee, Chulsung; Fried, Daniel

    2010-03-05

    The objective of this work was to observe the various thermal-induced optical changes that occur in the near-infrared (NIR) during drilling in dentin and enamel with the laser and the high-speed dental handpiece. Tooth sections of ~ 3 mm-thickness were prepared from extracted human incisors (N=60). Samples were ablated with a mechanically scanned CO(2) laser operating at a wavelength of 9.3-µm, a 300-Hz laser pulse repetition rate, and a laser pulse duration of 10-20 µs. An InGaAs imaging camera was used to acquire real-time NIR images at 1300-nm of thermal and mechanical changes (cracks). Enamel was rapidly removed by the CO(2) laser without peripheral thermal damage by mechanically scanning the laser beam while a water spray was used to cool the sample. Comparison of the peripheral thermal and mechanical changes produced while cutting with the laser and the high-speed hand-piece suggest that enamel and dentin can be removed at high speed by the CO(2) laser without excessive peripheral thermal or mechanical damage. Only 2 of the 15 samples ablated with the laser showed the formation of small cracks while 9 out of 15 samples exhibited crack formation with the dental hand-piece. The first indication of thermal change is a decrease in transparency due to loss of the mobile water from pores in the enamel which increase light-scattering. To test the hypothesis that peripheral thermal changes were caused by loss of mobile water in the enamel, thermal changes were intentionally induced by heating the surface. The mean attenuation coefficient of enamel increased significantly from 2.12 ± 0.82 to 5.08 ± 0.98 with loss of mobile water due to heating.

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

    Science.gov (United States)

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

    2014-06-01

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

  10. Blood flow dynamics after laser therapy of port wine stain birthmarks

    Science.gov (United States)

    Huang, Yu-Chih; Tran, Nadia; Ross, E. Victor; Shumaker, Peter R.; Nelson, J. Stuart; Kelly, Kristen; Choi, Bernard

    2009-02-01

    During laser therapy of port wine stain (PWS) birthmarks, regions of persistent perfusion may exist. We hypothesize that such regions, which are not readily visible, exist even during laser surgery performed by highly experienced clinicians. The objective of this study was to use objective feedback to assess the acute vascular response to laser therapy. We have developed a clinic-friendly laser speckle imaging (LSI) instrument to provide the clinician with real-time images of blood flow during laser therapy. We acquired images from patients undergoing laser therapy of PWS birthmarks at Scripps Clinic and Beckman Laser Institute and Medical Clinic. We extracted blood flow maps from the acquired imaging data. Collectively, we have observed two regimes of patient response to therapy: 1) an immediate increase in perfusion within minutes after laser therapy; and 2) an overall decrease in blood perfusion approximately one hour after laser therapy, with distinct regions of persistent perfusion apparent in the majority of post-treatment blood-flow images. A comparison of blood flow in PWS and adjacent normal skin demonstrated that PWS blood flow can be greater than or sometimes equivalent to that of normal skin. Regions of persistent perfusion frequently exist immediately after laser therapy of PWS birthmarks. Existence of these regions may be correlated to the need for multiple treatment sessions to improve substantially PWS skin appearance. With the use of intraoperative LSI, immediate retreatment of these regions may improve the outcome of each session.

  11. Effect of low level laser therapy and high intensity laser therapy on endothelial cell proliferation in vitro: preliminary communication

    Science.gov (United States)

    Lukowicz, Malgorzata; Szymanska, Justyna; Goralczyk, Krzysztof; Zajac, Andrzej; Rość, Danuta

    2013-01-01

    Background: The main purpose of this study was to analyze the influence of power intensity and wavelength of Low Level Laser Therapy (LLLT) and HILT (High Intensity Laser Therapy) on endothelial cell proliferation. Material and methods: The tests were done on human umbilical vein endothelial cells (HUVEC). Cultures were exposed to laser irradiation of 660 nm and 670 nm at different dosages, power output was 10 - 40 mW as well as 820 nm with power 100 mW and 808 nm with power 1500 mW. Energy density was from 0.28 to 11,43 J/cm2. Cell proliferation of a control and tested culture was evaluated with a colorimetric device to detect live cells. The tests were repeated 8 times. Results: We observed good effects of LLLT on live isolated ECs and no effects in experiments on previous deep-frozen cultures. Also HILT stimulated the proliferation of HUVEC. Conclusion: Endothelial cells play a key role in vascular homeostasis in humans. We observed the stimulatory effect of LLLT and HILT on proliferation of HUVEC. Many factors influence the proliferation of EC, so is it necessary to continue the experiment with different doses, intensity and cell concentration.

  12. Low-power laser therapy for carpal tunnel syndrome:effective optical power

    Institute of Scientific and Technical Information of China (English)

    Yan Chen; Cheng-qiang Zhao; Gang Ye; Can-dong Liu; Wen-dong Xu

    2016-01-01

    Low-power laser therapy has been used for the non-surgical treatment of mild to moderate carpal tunnel syndrome, although its efifca-cy has been a long-standing controversy. The laser parameters in low-power laser therapy are closely related to the laser effect on human tissue. To evaluate the efifcacy of low-power laser therapy, laser parameters should be accurately measured and controlled, which has been ignored in previous clinical trials. Here, we report the measurement of the effective optical power of low-power laser therapy for carpal tunnel syndrome. By monitoring the backside relfection and scattering laser power from human skin at the wrist, the effective laser power can be inferred. Using clinical measurements from 30 cases, we found that the effective laser power differed signiifcantly among cases, with the measured laser relfection coefifcient ranging from 1.8%to 54%. The relfection coefifcient for 36.7%of these 30 cases was in the range of 10–20%, but for 16.7%of cases, it was higher than 40%. Consequently, monitoring the effective optical power during laser irradiation is necessary for the laser therapy of carpal tunnel syndrome.

  13. Low-power laser therapy for carpal tunnel syndrome: effective optical power.

    Science.gov (United States)

    Chen, Yan; Zhao, Cheng-Qiang; Ye, Gang; Liu, Can-Dong; Xu, Wen-Dong

    2016-07-01

    Low-power laser therapy has been used for the non-surgical treatment of mild to moderate carpal tunnel syndrome, although its efficacy has been a long-standing controversy. The laser parameters in low-power laser therapy are closely related to the laser effect on human tissue. To evaluate the efficacy of low-power laser therapy, laser parameters should be accurately measured and controlled, which has been ignored in previous clinical trials. Here, we report the measurement of the effective optical power of low-power laser therapy for carpal tunnel syndrome. By monitoring the backside reflection and scattering laser power from human skin at the wrist, the effective laser power can be inferred. Using clinical measurements from 30 cases, we found that the effective laser power differed significantly among cases, with the measured laser reflection coefficient ranging from 1.8% to 54%. The reflection coefficient for 36.7% of these 30 cases was in the range of 10-20%, but for 16.7% of cases, it was higher than 40%. Consequently, monitoring the effective optical power during laser irradiation is necessary for the laser therapy of carpal tunnel syndrome.

  14. Tri-wave laser therapy for spinal cord injury, neuropathic pain management, and restoration of motor function

    Science.gov (United States)

    Chariff, Mark D.; Olszak, Peter

    2015-03-01

    A laser therapy device using three combined wavelengths 532nm, 808nm, and 1064nm has been demonstrated in clinical studies. Primarily, therapeutic lasers have used wavelengths in the ranges of 632nm through 1064nm, where the optical density (OD) pain relief and tissue regeneration. Conventional wisdom would argue against using wavelengths in the region of 532nm, due to poor penetration (OD ~ 8); however, the author's observations are to the contrary. The 532nm light is efficiently absorbed by chromophores such as oxyhemoglobin, deoxyhemoglobin, and cytochrome c oxidase thereby providing energy to accelerate the healing process. The 808nm light is known to result in Nitric Oxide production thereby reducing inflammation and oxidative stress. All three laser wavelengths likely contribute to pain relief by inhibiting nerve conduction; however, the 1064nm has the deepest penetration. Through the use of this device on over 1000 patients with a variety of acute and chronic neuro-musculoskeletal disorders, the author observed that a majority of these individuals experienced rapid relief from their presenting conditions and most patients reported a tingling sensation upon irradiation. Patient testimonials and thermal images have been collected to document the results of the laser therapy. These studies demonstrate the ability of laser therapy to rapidly alleviate pain from both acute and chronic conditions.

  15. Determination of Thermal Conductivity of Liquids by a Multi-Point Laser Pump Method

    Institute of Scientific and Technical Information of China (English)

    MA Di; KUO Pao-Kuang; XU Xiao-Dong; ZHANG Shu-Yi

    2007-01-01

    As an advanced optical method, a multi-point pump method is presented for measurements of thermo-physical properties of liquids. Meanwhile, based on the laser-induced thermal grating method, a new theory model is presented and used to analyse the thermal effects caused by the multi-point laser pump, by which the thermal conductivity of liquids can be obtained. The results of some typical liquids, such as water, ethanol and acetone, are presented and are consistent with those of acknowledged values, demonstrating that the multi-point method is simple and useful for characterizing thermal properties of liquids.

  16. Impurity and defect interactions during laser thermal annealing in Ge

    Energy Technology Data Exchange (ETDEWEB)

    Milazzo, R., E-mail: ruggero.milazzo@unipd.it; De Salvador, D.; Carnera, A.; Napolitani, E. [CNR-IMM MATIS and Dipartimento di Fisica e Astronomia, Università di Padova, Via Marzolo 8, 35131 Padova (Italy); Impellizzeri, G.; Privitera, V. [CNR-IMM MATIS and Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia 64, 95123 Catania (Italy); Piccinotti, D. [CNR-IMM MATIS and Dipartimento di Fisica e Astronomia, Università di Padova, Via Marzolo 8, 35131 Padova (Italy); IM2NP, CNRS-Universités d' Aix-Marseille et de Toulon, Case 142, 13397 Marseille Cedex 20 (France); La Magna, A. [CNR-IMM, Z.I. VIII Strada 5, 95121 Catania (Italy); Fortunato, G. [CNR-IMM, Via del Fosso del Cavaliere 100, 00133 Roma (Italy); Portavoce, A.; Mangelinck, D. [IM2NP, CNRS-Universités d' Aix-Marseille et de Toulon, Case 142, 13397 Marseille Cedex 20 (France)

    2016-01-28

    The microscopic mechanisms involving dopants, contaminants, and defects in Ge during pulsed melting laser thermal annealing (LTA) are investigated in detail. Samples both un-implanted and implanted with As or B are processed by LTA as well as characterized in terms of chemical (1D and 3D), electrical, and strain profiling. The clustering of As is directly measured by 3D chemical profiling and correlated with its partial electrical activation along with a reduction of the lattice strain induced by As atoms. A semi-quantitative microscopic model involving the interaction with mobile As-vacancy (AsV) complexes is proposed to describe the clustering mechanism. Boron is shown to follow different clustering behavior that changes with depth and marked by completely different strain levels. Oxygen penetrates from the surface into all the samples as a result of LTA and, only in un-implanted Ge, it occupies an interstitial position inducing also positive strain in the lattice. On the contrary, data suggest that the presence of As or B forces O to assume different configurations with negligible strain, through O-V or O-B interactions for the two dopant species, respectively. These data suggest that LTA does not inject a significant amount of vacancies in Ge, at variance with Si, unless As atoms or possibly other n-type dopants are present. These results have to be carefully considered for modeling the LTA process in Ge and its implementation in technology.

  17. Comparison of quality of facial scars after single low-level laser therapy and combined low-level with high-level (PDL 595 nm) laser therapy.

    Science.gov (United States)

    Vranova, Jana; Remlova, Eva; Jelinkova, Helena; Rosina, Jozef; Dostalova, Tatjana

    2015-01-01

    The main goal of our study was to compare the quality of resulting facials scar 12 weeks after single and combined laser therapy. Forty-one children from age 1.5 to 5 years with facial scars after injury participated in the study. Thirty-one underwent laser therapy, 14 were treated using single low-level laser therapy (670 nm, fluence 3-5 J/cm(-2) ), and 17 underwent combined high-level laser therapy with non-ablative pulsed dye laser (PDL; 595 nm, spot size 7 mm, delay 0.45 ms or 1.5 ms, fluence 9-11 J/cm(-2) , cryogen spray/delay 20/30 ms) and low-level laser therapy. The control group consisted of 10 untreated children. Before treatment and at week 4, 8, and, 12 the scars were evaluated using the POSAS questionnaire. A statistically significant improvement in scars (between ratings before treatment and 4 weeks after therapy, before treatment and 8 weeks after therapy and before treatment and 12 weeks after therapy) was observed in all parameters in both treatment groups (p < 0.0001). For the HLLT+LLLT group the most significant enhancement in the quality of scars was found for all items and at all evaluations, except pigmentation and pliability. There was no improvement observed in quality of facial scars in the control group.

  18. Influence of absorption induced thermal initiation pathway on irradiance threshold for laser induced breakdown

    Science.gov (United States)

    Varghese, Babu; Bonito, Valentina; Jurna, Martin; Palero, Jonathan; Verhagen, Margaret Hortonand Rieko

    2015-01-01

    We investigated the influence of thermal initiation pathway on the irradiance threshold for laser induced breakdown in transparent, absorbing and scattering phantoms. We observed a transition from laser-induced optical breakdown to laser-induced thermal breakdown as the absorption coefficient of the medium is increased. We found that the irradiance threshold after correction for the path length dependent absorption and scattering losses in the medium is lower due to the thermal pathway for the generation of seed electrons compared to the laser-induced optical breakdown. Furthermore, irradiance threshold gradually decreases with the increase in the absorption properties of the medium. Creating breakdown with lower irradiance threshold that is specific at the target chromophore can provide intrinsic target selectivity and improve safety and efficacy of skin treatment methods that use laser induced breakdown. PMID:25909007

  19. High-definition color image in dye thermal transfer printing by laser heating

    Science.gov (United States)

    Kitamura, Takashi

    1999-12-01

    In laser thermal transfer printing using dye sublimation type medium, a high definition and continuous tone image can be obtained easily because the laser beam is focused to small spot and heat energy can be controlled by the pulse width modulation of laser light. The donor ink sheet is composed of the laser absorbing layer and sublimation dye layer. The tone reproduction was depend on the mixture ratio of dye to binder and thickness of ink layer. The four color ink sheets such as cyan, magenta, yellow and black were prepared for color printing image which have a high resolution and good continuous tone reproduction using sublimation dye transfer printing by laser heating.

  20. Conventional operation and laser therapy in the treatment of varicose veins

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Objective: To evaluate the effectiveness of endovenous laser therapy and conventional therapy on the varicose of great saphenous vein. Methods: Thirty-two patients received endovenous laser therapy and 32 patients were operated by conventional therapy (high ligation and stripping). The observation results of great saphenous vein(GSV) were recorded by clinical evaluation and duplex ultrasound examination. And the operating time, intraoperative blood loss, time to become moveable, duration of hospitalization and degree of feeling pain were compared between the two groups. Results: Compared with conventional therapy, laser therapy had good curative effect with less complications and no scars and no pains. There were significant differences between the two groups (P<0.01). Conclusion: Laser therapy for varicose of great saphenous vein is better than the conventional therapy. It deserves to be widely used in clinical treatment.

  1. Comparison of cryotherapy and thermal therapy for breast cancer treatment simulations

    Science.gov (United States)

    Ryan, Thomas P.

    2001-05-01

    Breast cancer presents an ongoing challenge in regard to treatment efficacy and successful clinical outcomes. There has been a challenge to increase the survival rate over the past 50 years and only recently have clinical outcomes improved, although slightly. Thermal treatment regimes have been evolving and most recently, have been applied in situ. A standalone treatment for malignancies is challenging due to the rigor in achieving homogeneity in the distribution of therapeutic temperatures in the tumor and the lack of therapy in the adjacent normal tissue. Although initial work used lasers, contemporary work utilizes radiofrequency (RF) or cryotherapy as a treatment modality. Both monopolar and bipolar RF devices were modeled for the RF treatments in the breast. Using finite element techniques, these two modalities were simulated in breast tissue and the results of the bioheat equation compared for similar sized devices. The model incorporated changing electrical and thermal properties of tissue with temperature, as well as blood flow changes. For thermal treatment, the isotherm of +55 degree(s)C was considered the margin of coagulation necrosis, while for cryotreatment, the -40 degree(s)C isotherm was used. The comparison aids in the selection of the best method to improve clinical outcomes, while paying attention to the size of the applicator and time length of treatment.

  2. Thermal Performance of Laser Diode Array under Constant Convective Heat Transfer Boundary Condition

    Institute of Scientific and Technical Information of China (English)

    YIN Cong; HUANG Lei; HE Fa-Hong; GONG Ma-Li

    2007-01-01

    Three-dimensional heat transfer model of laser diode array under constant convective heat transfer coefficient boundary condition is established and analytical temperature profiles within its heat sink are obtained by separation of variables. The influences on thermal resistance and maximum temperature variation among emitters from heat sink structure parameters and convective heat transfer coefficient are brought forward. The derived formula enables the thermal optimization of laser diode array.

  3. Experimental and numerical investigation on the transient vascular thermal response to multi-pulse Nd:YAG laser.

    Science.gov (United States)

    Li, Dong; Li, Ruohui; Jia, Hao; Chen, Bin; Wu, Wenjuan; Ying, Zhaoxia

    2017-06-09

    Port wine stains (PWS) are congenital vascular malformations that progressively darken and thicken with age. Laser therapy is currently the most effective way in clinical practice for PWS. A 1,064 nm Nd:YAG laser in the near-infrared band can achieve a deeper treatment depth compared to the current widely adopted pulsed dye laser. However, because of its relatively weak absorption by blood, single-pulse Nd:YAG laser requires high energy density to cause effective vessel damage, but may inflict undesirable burning to surrounding collagen. Multi-pulse laser has great potential in clinical treatment because it needs less energy density for each pulse. This paper presented an experimental and theoretical study of the transient thermal effects of low-energy multi-pulse Nd:YAG laser on blood vessels. In vivo experiments were performed on dorsal skin chamber. By using a high speed camera (up to 2,000 fps), the complete and dynamic thermal response of blood vessels during laser irradiation and between pulse intervals was obtained. In vitro experiment in capillary tubes and Numerical simulations by two-scale heat transfer model were also conducted to further explore the in vivo experimental findings. The complete and dynamic response of blood vessels were obtained, including vessel dilation, thrombus formation, partial vessel constriction, thread-like constriction, cavitation and bubbles, and hemorrhage. Thread-like constriction is the desirable treatment end point, which will only occur after thrombus completely occludes the vessel lumen. Cavitation can cause hemorrhage when thrombus fails to occlude the vessel lumen. In vitro experiment found that vessel constriction was due to the constriction of thrombus induced by laser irradiation. Theoretical investigation revealed that the mechanism for the effective reduction of energy density by multi-pulse Nd:YAG laser was due to enhanced light absorption of the blood with thrombus formation. For multi-pulse treatment, laser

  4. Thermal elasto-plastic stress analysis during laser heating of a metal plate

    Science.gov (United States)

    Chen, Yanbei; Lu, Jian; Ni, Xiaowu

    2008-03-01

    During laser heating of a metal material, the continuity of material confines its free expansion, thermal stresses arise. On one hand the thermal expansion of the heated zone of the material increases with the increase of temperature, the thermal stress level increases correspondingly; on the other hand the mechanical properties of the material will change with the increase of temperature, especially the elastic modulus, yield strength and tensile strength drop significantly, which is the so-called thermal softening problem. Due to the effect of the two factors, as the heating time or the intensity of the laser beam increases, it is possible that the stress levels of the heated zone of the material exceed the yield strength, which leads the material to come into a plastic stage. Thus, a thermal plastic problem occurs. In this study, thermal elasto-plastic stresses during laser heating of a metal plate are computed by the finite element method (FEM) based on thermal elasto-plastic constitutive theory. The mechanical behaviors of the metal material during the laser heating are analyzed. By the analysis of the results, it is found that thermal expansion leads to the increase of stress level early during the laser irradiating, and thermal softening causes the decrease of stress levels in the plastic zone and the slow growth and even decrease of stress levels in elastic zone later. The radial stresses are all compressive stresses, and the hoop stresses are compressive stresses within about the laser spot and are tensile stresses at other place. This work may be beneficial to the laser processing of metal materials.

  5. Laser therapy of the lung: biophysical background; Lasertherapie in der Lunge: Biophysikalischer Hintergrund

    Energy Technology Data Exchange (ETDEWEB)

    Knappe, V. [Laser- und Medizin-Technologie GmbH Berlin, Berlin (Germany); Mols, A. [Campus Benjamin Franklin, Charite - Universitaetsmedizin Berlin (Germany)

    2004-07-01

    The laser is a well established surgical instrument in lung therapy. This report provides information on the biophysical basics of the laser-induced thermotherapy (LITT) of lung metastases. Optical properties like absorption and scattering determine the penetration depth of laser radiation in tissue. These parameters vary dynamically during the application and define in combination with thermal tissue properties the achievable destruction volume. Parenchyma behaves very differently compared to more dense tissues due to local inhomogenities and the large amount cavaties filled with air. Beside an account of the affecting parameters an overview of therapy options is given. Therapeutic results depend not only on the tissue properties but also on the technical equipment, e.g. the applicator design and the energy applied. Complex dosimetric models allow for a calculation of the lesion's size in advance. (orig.) [German] Der Laser ist in der Lungenchirurgie ein bereits etabliertes Instrument. In diesem Beitrag werden speziell die biophysikalischen Hintergruende der laserinduzierten Thermotherapie (LITT) von Lungenmetastasen beschrieben. In der Gewebeoptik determinieren Absorption und Streuung die Eindringtiefe von Laserlicht. Diese Parameter veraendern sich dynamisch waehrend der Anwendung und bestimmen in Verbindung mit den thermischen Gewebeeigenschaften die maximal erzielbaren Destruktionsvolumina. Lokale Inhomogenitaeten und der hohe Anteil luftgefuellter Hohlraeume unterscheiden das Parenchym in dieser Hinsicht signifikant von dichteren Geweben. Neben einer Darstellung der beeinflussenden Parameter wird ein Ueberblick ueber die Therapieoptionen gegeben. Der Therapieerfolg haengt neben den genannten gewebeseitigen Parametern von Anzahl und Geometrie der Applikatoren und der applizierten Energie ab und kann mit komplexen Dosimetriemodellen im voraus kalkuliert werden. (orig.)

  6. Emission spectra of YAG:Er3+ under pulse laser-thermal excitation

    Science.gov (United States)

    Marchenko, V. M.; Shakir, Yu. A.

    2016-12-01

    Spectra and kinetics of emission of YAG:0.5% Er3+ monocrystal in visible and NIR ranges were investigated under laser-thermal excitation by the pulses of CO2 laser of 100 ns duration at wavelength λ = 10,6 μμm. Kinetics of integral emission was interpreted.

  7. Thermal energy transfer by plasmon-resonant composite nanoparticles at pulse laser irradiation.

    Science.gov (United States)

    Avetisyan, Yuri A; Yakunin, Alexander N; Tuchin, Valery V

    2012-04-01

    Heating of composite plasmon-resonant nanoparticles (spherical gold nanoshells) under pulse laser illumination is considered. The numerical solution of the time-dependent heat conduction equation accounting for spatial inhomogeneities of absorbed laser radiation is performed. Important features of temperature kinetics and thermal flux inside nanoparticles are analyzed. Possible applications of the observed effects in nanotechnology and medicine are discussed.

  8. Thermal processing of thin films using ultra-short laser pulses: applied to photovoltaic materials

    NARCIS (Netherlands)

    Scorticati, D.

    2015-01-01

    In this thesis a novel approach to raise the thermal selectivity of superficial heat treatments, exploiting ultra-short laser pulses, is proposed and studied. That is, the effective applicability of ultrafast lasers for selective heat treatments is proven by increasing the performance of different

  9. Thin-disk laser scaling limit due to thermal-lens induced misalignment instability

    CERN Document Server

    Schuhmann, Karsten; Nez, Francois; Pohl, Randolf; Antognini, Aldo

    2016-01-01

    We present an obstacle in power scaling of thin-disk lasers related with self-driven growth of misalignment due to thermal lens effects. This self-driven growth arises from the changes of the optical phase difference at the disk caused by the excursion of the laser eigen-mode from the optical axis. We found a criterion based on a simplified model of this phenomenon which can be appied to design laser resonators insensitive to this effect.

  10. The effect of low-level laser therapy on hearing.

    Science.gov (United States)

    Goodman, Shawn S; Bentler, Ruth A; Dittberner, Andrew; Mertes, Ian B

    2013-01-01

    One purported use of low-level laser therapy (LLLT) is to promote healing in damaged cells. The effects of LLLT on hearing loss and tinnitus have received some study, but results have been equivocal. The purpose of this study was to determine if LLLT improved hearing, speech understanding, and/or cochlear function in adults with hearing loss. Using a randomized, double-blind, placebo-controlled design, subjects were assigned to a treatment, placebo, or control group. The treatment group was given LLLT, which consisted of shining low-level lasers onto the outer ear, head, and neck. Each laser treatment lasted approximately five minutes. Three treatments were applied within the course of one week. A battery of auditory tests was administered immediately before the first treatment and immediately after the third treatment. The battery consisted of pure-tone audiometry, the Connected Speech Test, and transient-evoked otoacoustic emissions. Data were analyzed by comparing pre- and posttest results. No statistically significant differences were found between groups for any of the auditory tests. Additionally, no clinically significant differences were found in any individual subjects. This trial is registered with ClinicalTrials.gov (NCT01820416).

  11. Laser acupuncture versus reflexology therapy in elderly with rheumatoid arthritis.

    Science.gov (United States)

    Adly, Afnan Sedky; Adly, Aya Sedky; Adly, Mahmoud Sedky; Serry, Zahra M H

    2017-07-01

    The purposes of this study are to determine and compare efficacy of laser acupuncture versus reflexology in elderly with rheumatoid arthritis. Thirty elderly patients with rheumatoid arthritis aged between 60 and 70 years were classified into two groups, 15 patients each. Group A received laser acupuncture therapy (904 nm, beam area of 1cm(2), power 100 mW, power density 100 mW/cm(2), energy dosage 4 J, energy density 4 J/cm(2), irradiation time 40 s, and frequency 100,000 Hz). The acupuncture points that were exposed to laser radiation are LR3, ST25, ST36, SI3, SI4, LI4, LI11, SP6, SP9, GB25, GB34, and HT7. While group B received reflexology therapy, both offered 12 sessions over 4 weeks. The changes in RAQoL, HAQ, IL-6, MDA, ATP, and ROM at wrist and ankle joints were measured at the beginning and end of treatment. There was significant decrease in RAQoL, HAQ, IL-6, and MDA pre/posttreatment for both groups (p < 0.05); significant increase in ATP pre/posttreatment for both groups (p < 0.05); significant increase in ankle dorsi-flexion, plantar-flexion, wrist flexion, extension, and ulnar deviation ROM pre/posttreatment in group A (p < 0.05); and significant increase in ankle dorsi-flexion and ankle plantar-flexion ROM pre/posttreatment in group B (p < 0.05). Comparison between both groups showed a statistical significant decrease in MDA and a statistical significant increase in ATP in group A than group B. Percent of changes in MDA was 41.82%↓ in group A versus 21.68%↓ in group B; changes in ATP was 226.97%↑ in group A versus 67.02%↑ in group B. Moreover, there was a statistical significant increase in ankle dorsi-flexion, ankle plantar-flexion, wrist flexion, wrist extension, and radial deviation in group A than group B. Laser therapy is associated with significant improvement in MDA and ATP greater than reflexology. In addition, it is associated with significant improvement in ankle dorsi-flexion, ankle plantar-flexion, wrist flexion

  12. Inverse Thermal Analysis of Alloy 690 Laser and Hybrid Laser-GMA Welds Using Solidification-Boundary Constraints

    Science.gov (United States)

    Lambrakos, S. G.

    2017-08-01

    An inverse thermal analysis of Alloy 690 laser and hybrid laser-GMA welds is presented that uses numerical-analytical basis functions and boundary constraints based on measured solidification cross sections. In particular, the inverse analysis procedure uses three-dimensional constraint conditions such that two-dimensional projections of calculated solidification boundaries are constrained to map within experimentally measured solidification cross sections. Temperature histories calculated by this analysis are input data for computational procedures that predict solid-state phase transformations and mechanical response. These temperature histories can be used for inverse thermal analysis of welds corresponding to other welding processes whose process conditions are within similar regimes.

  13. Thermal desorption from surfaces with laser-induced defects

    Energy Technology Data Exchange (ETDEWEB)

    Szabelski, Pawel; Panczyk, Tomasz; Rudzinski, Wladyslaw

    2002-12-30

    Monte Carlo simulation method was used to mimic surface damage development caused by short laser pulses. The influence of pulsed laser irradiation on the creation of defect concentration was examined in the case of a model surface. In particular, the dependence of the intact surface area on a number of laser scans was studied and compared with the experimental results obtained for Rh(1 1 1) crystal face. Changes in the adsorptivoperties of the surface produced by laser irradiation are explained with the help of a simple geometric model connecting the laser intensity and the disordered area generated by a single laser shot. It was demonstrated that exponential decay of the Low Energy Electron Diffraction (LEED) signal with the number of laser scans, which is observed experimentally, may result directly from the overlapping of the laser spots created on the surface. This effect becomes enhanced when the laser intensity, hence the spot size, increases. The importance of laser-induced defects in the kinetics of catalytic/separation processes was examined in the case of temperature programmed desorption (TPD) spectra from surfaces subjected to a different number of laser shots. The spectra were simulated by employing the Monte Carlo method as well as by application of the absolute rate theory (ART) coupled with the mean field approximation. The results obtained with both methods were in a good agreement even when weak lateral interactions in the adsorbed phase were allowed.

  14. Could low level laser therapy and highly active antiretroviral therapy lead to complete eradication of HIV-1 in vitro?

    Science.gov (United States)

    Lugongolo, Masixole Yvonne; Manoto, Sello Lebohang; Ombinda-Lemboumba, Saturnin; Maaza, Malik; Mthunzi-Kufa, Patience

    2017-02-01

    Human immunodeficiency virus (HIV-1) infection remains a major health problem despite the use of highly active antiretroviral therapy (HAART), which has greatly reduced mortality rates. Due to the unavailability of an effective vaccine or a treatment that would completely eradicate the virus, the quest for new and combination therapies continues. In this study we explored the influence of Low Level Laser Therapy (LLLT) in HIV-1 infected and uninfected cells. Literature reports LLLT as widely used to treat different medical conditions such as diabetic wounds, sports injuries and others. The technique involves exposure of cells or tissue to low levels of red and near infrared laser light. Both HIV infected and uninfected cells were laser irradiated at a wavelength of 640 nm with fluencies ranging from 2 to 10 J/cm2 and cellular responses were assessed 24 hours post laser treatment. In our studies, laser therapy had no inhibitory effects in HIV-1 uninfected cells as was indicated by the cell morphology and proliferation results. However, laser irradiation enhanced cell apoptosis in HIV-1 infected cells as the laser fluencies increased. This led to further studies in which laser irradiation would be conducted in the presence of HAART to determine whether HAART would minimise the detrimental effects of laser irradiation in infected cells.

  15. The effects of low-level laser therapy on xerostomia (mouth dryness

    Directory of Open Access Journals (Sweden)

    Pavlić Verica

    2012-01-01

    Full Text Available Introduction. Xerostomia is a subjective complaint of mouth/oral dryness, caused by a reduction in normal salivary secretion due to different causes. Even though there are many available treatment modalities to enhance salivary flow, the therapy often remains unsatisfactory. The low-level laser therapy (low-level laser irradiation, photo-biomodulation has been extensively used as a new, non-invasive approach and advantageous tool for reduction of xerostomia. Therefore, the aim of this study is to give a systematic overview on the effects of low-level laser therapy on xerostomia. Material and Methods. A systematic review of published articles in PubMed database was carried out using keywords: ”low-level laser therapy”, ”xerostomia”, ”mouth dryness”. Results. In all published articles, which were considered adequate for this overview, positive effects of low-level laser therapy were reported. Low-level laser therapy could significantly enhance salivary secretion and improve antimicrobial characteristics of secreted saliva (increased level of secretory immunoglobulin A; sIgA. Furthermore, low-level laser therapy could improve salivary flow and regeneration of salivary duct epithelial cells. Conclusion. The current literature suggests that low-level laser therapy can be safely and effectively used as an advanced treatment modality for reduction of xerostomia. Further in vivo, in vitro and clinical studies using different irradiation parameters are suggested to determine the best laser parameters to be used.

  16. Laser thermal annealing of Ge, optimized for highly activated dopants and diode ION/IOFF ratios

    DEFF Research Database (Denmark)

    Shayesteh, M.; O'Connell, D.; Gity, F.;

    2014-01-01

    The authors compared the influence of laser thermal annealing (LTA) and rapid thermal annealing (RTA) on dopant activation and electrical performance of phosphorus and arsenic doped n+/p junction. High carrier concentration above 1020 cm-3 as well as an ION/IOFF ratio of approximately 105 and ide...

  17. In-Flight Thermal Performance of the Geoscience Laser Altimeter System (GLAS) Instrument

    Science.gov (United States)

    Grob, Eric; Baker, Charles; McCarthy, Tom

    2003-01-01

    The Geoscience Laser Altimeter System (GLAS) instrument is NASA Goddard Space Flight Center's first application of Loop Heat Pipe technology that provides selectable/stable temperature levels for the lasers and other electronics over a widely varying mission environment. GLAS was successfully launched as the sole science instrument aboard the Ice, Clouds, and Land Elevation Satellite (ICESat) from Vandenberg AFB at 4:45pm PST on January 12, 2003. After SC commissioning, the LHPs started easily and have provided selectable and stable temperatures for the lasers and other electronics. This paper discusses the thermal development background and testing, along with details of early flight thermal performance data.

  18. Injectable liquid alkali alloy based-tumor thermal ablation therapy.

    Science.gov (United States)

    Rao, Wei; Liu, Jing

    2009-01-01

    The alkali metal was recently found to be a very useful agent for inducing minimally invasive tumor hyperthermia therapy. However, the solid-like metal makes it somewhat inconvenient to perform the surgery. Here, to overcome this drawback, the NaK alloy in liquid state at room temperature was proposed as a highly efficient thermal ablative agent for tumor treatment. For illustration purposes, the functionalized liquid NaK alloy at a mass ratio 1:1 was obtained and an amount of 0.35 ml was injected into in vitro pork. The sizes of the damage region and temperature response were measured. It was found that significant temperature increase by a magnitude of > 80 degrees C can easily be obtained. This produced a large coagulation and necrotic area within selected areas for in vitro tests and the necrotic region volume is three times that of the NaK injection quantity. Furthermore, for the in vivo experiment, breast EMT6 tumor in mouse was subjected to treatment by NaK alloy. Tumor was harvested after the experiment to assess its viability. Histological section showed complete necrosis at the target site. These conceptual results demonstrate that using injectable liquid alkali alloy to ablate tumor is rather promising. This study also raised interesting issues waiting for clarification in future technical and animal studies aiming to assess efficacy, side effects and safety of the new therapy.

  19. Therapeutic and diagnostic set for irradiation the cell lines in low level laser therapy

    Science.gov (United States)

    Gryko, Lukasz; Zajac, Andrzej; Gilewski, Marian; Szymanska, Justyna; Goralczyk, Krzysztof

    2014-05-01

    In the paper is presented optoelectronic diagnostic set for standardization the biostimulation procedures performed on cell lines. The basic functional components of the therapeutic set are two digitally controlled illuminators. They are composed of the sets of semiconductor emitters - medium power laser diodes and high power LEDs emitting radiation in wide spectral range from 600 nm to 1000 nm. Emitters are coupled with applicator by fibre optic and optical systems that provides uniform irradiation of vessel with cell culture samples. Integrated spectrometer and optical power meter allow to control the energy and spectral parameters of electromagnetic radiation during the Low Level Light Therapy procedure. Dedicated power supplies and digital controlling system allow independent power of each emitter . It was developed active temperature stabilization system to thermal adjust spectral line of emitted radiation to more efficient association with absorption spectra of biological acceptors. Using the set to controlled irradiation and allowing to measure absorption spectrum of biological medium it is possible to carry out objective assessment the impact of the exposure parameters on the state cells subjected to Low Level Light Therapy. That procedure allows comparing the biological response of cell lines after irradiation with radiation of variable spectral and energetic parameters. Researches were carried out on vascular endothelial cell lines. Cells proliferations after irradiation of LEDs: 645 nm, 680 nm, 740 nm, 780 nm, 830 nm, 870 nm, 890 nm, 970 nm and lasers 650 nm and 830 nm were examined.

  20. Effectiveness of Laser Therapy in the Management of Recurrent Aphthous Stomatitis: A Systematic Review

    Science.gov (United States)

    Fang, Hui; Cao, Ying; Xia, Rong; Zhang, Zhi-Hong

    2016-01-01

    Objectives. Laser therapy is a promising new treatment for patients with recurrent aphthous stomatitis (RAS). However, the clinical effect and security issue of laser therapy remain controversial. This systematic review was conducted to evaluate the clinical effectiveness and security of laser treatment in RAS patients. Methods. Five electronic databases were searched (MEDLINE (PubMed), EMBASE, ScienceDirect, the Cochrane Library, and Web of Science) to identify all studies that were about randomized controlled clinical trials, involving the effect of laser therapy in RAS patients. Conclusion. Twenty-three studies were retained for full-text analysis after screening the titles and abstracts of potential articles, but only 10 studies satisfied the inclusion criteria after the full texts were reviewed. The included studies reported a comparison of the effectiveness between the laser treatment and placebo laser therapy (or conventional drug therapy) when managing the RAS patients. It can be concluded that laser therapy has the superiority in relieving ulcer pain and shortening healing time when compared with placebo group or medical treatment group. Although laser therapy is a promising effective treatment for RAS, high-quality clinical studies with large sample size must be further performed to confirm the effectiveness of this therapy. PMID:28078164

  1. A novel contactless technique for thermal field mapping and thermal conductivity determination: two-laser Raman thermometry.

    Science.gov (United States)

    Reparaz, J S; Chavez-Angel, E; Wagner, M R; Graczykowski, B; Gomis-Bresco, J; Alzina, F; Sotomayor Torres, C M

    2014-03-01

    We present a novel contactless technique for thermal conductivity determination and thermal field mapping based on creating a thermal distribution of phonons using a heating laser, while a second laser probes the local temperature through the spectral position of a Raman active mode. The spatial resolution can be as small as 300 nm, whereas its temperature accuracy is ±2 K. We validate this technique investigating the thermal properties of three free-standing single crystalline Si membranes with thickness of 250, 1000, and 2000 nm. We show that for two-dimensional materials such as free-standing membranes or thin films, and for small temperature gradients, the thermal field decays as T(r) ∝ ln(r) in the diffusive limit. The case of large temperature gradients within the membranes leads to an exponential decay of the thermal field, T ∝ exp[ - A·ln(r)]. The results demonstrate the full potential of this new contactless method for quantitative determination of thermal properties. The range of materials to which this method is applicable reaches far beyond the here demonstrated case of Si, as the only requirement is the presence of a Raman active mode.

  2. Thermal dynamics-based mechanism for intense laser-induced material surface vaporization

    Indian Academy of Sciences (India)

    N Kumar; S Dash; A K Tyagi; Baldev Raj

    2008-09-01

    Laser material processing involving welding, ablation and cutting involves interaction of intense laser pulses of nanosecond duration with a condensed phase. Such interaction involving high brightness radiative flux causes multitude of non-linear events involving thermal phase transition at soild–liquid–gas interfaces. A theoretical perspective involving thermal dynamics of the vaporization process and consequent non-linear multiple thermal phase transitions under the action of laser plasma is the subject matter of the present work. The computational calculations were carried out where titanium (Ti) was treated as a condensed medium. The solution to the partial differential equations governing the thermal dynamics and the underlying phase transition event in the multiphase system is based on non-stationary Eulerian variables. The Mach number depicts significant fluctuations due to thermal instabilities associated with the laser beam flux and intensity. A conclusive amalgamation has been established which relates material surface temperature profile to laser intensity, laser flux and the pressure in the plasma cloud.

  3. Noninvasive imaging analysis of biological tissue associated with laser thermal injury.

    Science.gov (United States)

    Chang, Cheng-Jen; Yu, De-Yi; Hsiao, Yen-Chang; Ho, Kuang-Hua

    2017-04-01

    The purpose of our study is to use a noninvasive tomographic imaging technique with high spatial resolution to characterize and monitor biological tissue responses associated with laser thermal injury. Optical doppler tomography (ODT) combines laser doppler flowmetry (LDF) with optical coherence tomography (OCT) to obtain high resolution tomographic velocity and structural images of static and moving constituents in highly scattering biological tissues. A SurgiLase XJ150 carbon dioxide (CO2) laser using a continuous mode of 3 watts (W) was used to create first, second or third degree burns on anesthetized Sprague-Dawley rats. Additional parameters for laser thermal injury were assessed as well. The rationale for using ODT in the evaluation of laser thermal injury offers a means of constructing a high resolution tomographic image of the structure and perfusion of laser damaged skin. In the velocity images, the blood flow is coded at 1300 μm/s and 0 velocity, 1000 μm/s and 0 velocity, 700 μm/s and 0 velocity adjacent to the first, second, and third degree injuries, respectively. ODT produces exceptional spatial resolution while having a non-invasive way of measurement, therefore, ODT is an accurate measuring method for high-resolution fluid flow velocity and structural images for biological tissue with laser thermal injury. Copyright © 2017 Chang Gung University. Published by Elsevier B.V. All rights reserved.

  4. Comparative study of Low-level laser therapy and microcurrent on the healing of skin burns in rats

    Directory of Open Access Journals (Sweden)

    Rodrigo Pegado de Abreu Freitas

    2014-03-01

    This study investigated and compared the effects of low-level laser therapy (LLLT and microcurrent in the burn healing process in Wistar rats. We conducted a randomized controlled study with 30 rats divided into 3 groups (n = 10; control group (CG, laser group (LG and microcurrent group (MG. After thermal damage, 10 applications of 660 nm diode laser were performed in GL and 10 applications of 60 Hz microcurrent (160 μA in MG. The semi-quantitative histological analysis was done using scores (0–3, in sections stained by hematoxylin and eosin and Masson’s trichrome. The results indicated a significant improvement in the fibroblasts proliferation, collagen fibers deposition, neoangiogenesis, and cutaneous appendages regeneration in MG and LG. When microcurrent and LLLT were compared, no difference was detected, except the regeneration and formation of new cutaneous appendages, observed in MG. Despite the similar effects, GM showed faster tissue repair with the formation of skin appendages.

  5. The first- and second-order temporal interference between thermal and laser light

    CERN Document Server

    Liu, Jianbin; Chen, Hui; Zhou, Yu; Li, Fu-li; Xu, Zhuo

    2014-01-01

    The first- and second-order temporal interference between two independent thermal and laser light beams is discussed by employing the superposition principle in Feynman's path integral theory. It is concluded that the first-order temporal interference pattern can not be observed by superposing thermal and laser light, while the second-order temporal interference pattern can be observed in the same condition. These predictions are experimentally verified by employing pseudothermal light to simulate thermal light. The conclusions and method in the paper can be generalized to any order interference of light or massive particles, which is helpful to understand the physics of interference.

  6. Optimized Laser Thermal Annealing on Germanium for High Dopant Activation and Low Leakage Current

    DEFF Research Database (Denmark)

    Shayesteh, Maryam; O' Connell, Dan; Gity, Farzan

    2014-01-01

    In this paper, state-of-the-art laser thermal annealing is used to fabricate Ge diodes. We compared the effect of laser thermal annealing (LTA) and rapid thermal annealing (RTA) on dopant activation and electrical properties of phosphorus and Arsenic-doped n +/p junctions. Using LTA, high carrier...... implant conditions. On the other hand, RTA revealed very high I on/I off ratio ∼ 107 and n ∼ 1, at the cost of high dopant diffusion and lower carrier concentrations which would degrade scalability and access resistance....

  7. Mirror thermal noise in laser interferometer gravitational wave detectors operating at room and cryogenic temperature

    CERN Document Server

    Franc, Janyce; Flaminio, Raffaele; Nawrodt, Ronny; Martin, Iain; Cunningham, Liam; Cumming, Alan; Rowan, Sheila; Hough, James

    2009-01-01

    Mirror thermal noise is and will remain one of the main limitations to the sensitivity of gravitational wave detectors based on laser interferometers. We report about projected mirror thermal noise due to losses in the mirror coatings and substrates. The evaluation includes all kind of thermal noises presently known. Several of the envisaged substrate and coating materials are considered. The results for mirrors operated at room temperature and at cryogenic temperature are reported.

  8. The double-end-pumped cubic Nd:YVO4 laser: Temperature distribution and thermal stress

    Indian Academy of Sciences (India)

    P Elahi; S Morshedi

    2010-01-01

    Thermal effects of a double-end-pumped cubic Nd:YVO4 laser crystal are investigated in this paper. A detailed analysis of temperature distribution and thermal stress in cubic crystal with circular shape pumping is discussed. It has been shown that by considering the total input powers as constant, the double-end-pumped configurations with equal pump power can be considered as having a minimum thermal effect with respect to the other end-pumped configuration.

  9. Jones calculus modeling and analysis of the thermal distortion in a Ti:sapphire laser amplifier.

    Science.gov (United States)

    Cho, Seryeyohan; Jeong, Jihoon; Yu, Tae Jun

    2016-06-27

    The mathematical modeling of an anisotropic Ti:sapphire crystal with a significant thermal load is performed. The model is expressed by the differential Jones matrix. A thermally induced distortion in the chirped-pulse amplification process is shown by the solution of the differential Jones matrix. Using this model, the thermally distorted spatio-temporal laser beam shape is calculated for a high-power and high-repetition-rate Ti:sapphire amplifier.

  10. Analytical model for ring heater thermal compensation in the Advanced Laser Interferometer Gravitational-wave Observatory.

    Science.gov (United States)

    Ramette, Joshua; Kasprzack, Marie; Brooks, Aidan; Blair, Carl; Wang, Haoyu; Heintze, Matthew

    2016-04-01

    Advanced laser interferometer gravitational-wave detectors use high laser power to achieve design sensitivity. A small part of this power is absorbed in the interferometer cavity mirrors where it creates thermal lenses, causing aberrations in the main laser beam that must be minimized by the actuation of "ring heaters," which are additional heater elements that are aimed to reduce the temperature gradients in the mirrors. In this article we derive the first, to the best of our knowledge, analytical model of the temperature field generated by an ideal ring heater. We express the resulting optical aberration contribution to the main laser beam in this axisymmetric case. Used in conjunction with wavefront measurements, our model provides a more complete understanding of the thermal state of the cavity mirrors and will allow a more efficient use of the ring heaters in the Advanced Laser Interferometer Gravitational-wave Observatory.

  11. Thermal Changes in the Hard Dental Tissue at Diode Laser Root Canal Treatment

    Directory of Open Access Journals (Sweden)

    Uzunov Ts.

    2014-12-01

    Full Text Available The laser coagulation at the apical part of the root canal after vital extirpation is a proper method of preventing complications such as pain, bleeding, remaining vital pulp. The aim of the present survey is to register the thermal changes that occur on the tooth surfaces during laser treatment of the root canal after vital extirpation. An in vitro study of 30 extracted teeth has been conducted. The teeth have been prepared with ProTaper nickel-titanium machine tools and wiped dry. During the course of laser treatment of root canals with a diode laser DenLase temperatures, changes of the surface of the hard dental tissues have been recorded with infrared camera FLIR T330. The captured thermal images have been processed with software product Flir Reporter Pro 9. In conclusion, temperature changes in hard dental tissues at diode laser treatment of the root canal are biocompatible.

  12. The three dimensional laser induced temperature distribution in photo-thermal displacement spectroscopy

    CERN Document Server

    Soltanolkotabi, M

    2002-01-01

    In this paper we present a detailed theoretical treatment of 3-D temperature distribution induced by laser beam in photothermal displacement spectroscopy. We assume that a solid sample, which is deposited on a substrate and is in contact with a fluid, is irradiated by an intensity modulated cw laser source. By using a technique based on Green's function and integral transformations we find the explicit expression for temperature distribution function. This function which depends on the properties of the laser beam and optical and thermal properties of the sample, the substrate and the fluid, exhibits the characteristics of a damped thermal wave. Numerical analysis of the temperature distribution for a certain sample (GaAs) reveals that the behavior of thermal wave is not so sensitive with respect to the variation of the modulation frequency. On the other hand, we find that the temperature of the sample surface decreases with increasing modulation frequency because of the thermal inter tia of the sample. Furth...

  13. THERMAL LENSING MEASUREMENTS IN THE ANISOTROPIC LASER CRYSTALS UNDER DIODE PUMPING

    Directory of Open Access Journals (Sweden)

    P. A. Loiko

    2012-01-01

    Full Text Available An experimental setup was developed for thermal lensing measurements in the anisotropic diode-pumped laser crystals. The studied crystal is placed into the stable two-mirror laser cavity operating at the fundamental transversal mode. The output beam radius is measured with respect to the pump intensity for different meridional planes (all these planes contain the light propagation direction. These dependencies are fitted using the ABCD matrix method in order to obtain the sensitivity factors showing the change of the optical power of thermal lens due to variation of the pump intensity. The difference of the sensitivity factors for two mutually orthogonal principal meridional planes describes the thermal lens astigmatism degree. By means of this approach, thermal lensing was characterized in the diode-pumped monoclinic Np-cut Nd:KGd(WO42 laser crystal at the wavelength of 1.067 μm for light polarization E || Nm.

  14. Heat transfer analysis of skin during thermal therapy using thermal wave equation.

    Science.gov (United States)

    Kashcooli, Meisam; Salimpour, Mohammad Reza; Shirani, Ebrahim

    2017-02-01

    Specifying exact geometry of vessel network and its effect on temperature distribution in living tissues is one of the most complicated problems of the bioheat field. In this paper, the effects of blood vessels on temperature distribution in a skin tissue subjected to various thermal therapy conditions are investigated. Present model consists of counter-current multilevel vessel network embedded in a three-dimensional triple-layered skin structure. Branching angles of vessels are calculated using the physiological principle of minimum work. Length and diameter ratios are specified using length doubling rule and Cube law, respectively. By solving continuity, momentum and energy equations for blood flow and Pennes and modified Pennes bioheat equations for the tissue, temperature distributions in the tissue are measured. Effects of considering modified Pennes bioheat equation are investigated, comprehensively. It is also observed that blood has an impressive role in temperature distribution of the tissue, especially at high temperatures. The effects of different parameters such as boundary conditions, relaxation time, thermal properties of skin, metabolism and pulse heat flux on temperature distribution are investigated. Tremendous effect of boundary condition type at the lower boundary is noted. It seems that neither insulation nor constant temperature at this boundary can completely describe the real physical phenomena. It is expected that real temperature at the lower levels is somewhat between two predicted values. The effect of temperature on the thermal properties of skin tissue is considered. It is shown that considering temperature dependent values for thermal conductivity is important in the temperature distribution estimation of skin tissue; however, the effect of temperature dependent values for specific heat capacity is negligible. It is seen that considering modified Pennes equation in processes with high heat flux during low times is significant

  15. Advances in Thermal Modeling of Selective Laser Sintering of Metal Powders

    CERN Document Server

    Xiao, Bin

    2016-01-01

    Selective laser sintering (SLS) of single component metal powders is a rapid prototyping technology in which a high-energy laser beam scans, melts, shrinks and consolidates metal powders with single component. For better understanding physical mechanisms during laser sintering of single-component metal particles, a temperature transforming model with the consideration of shrinkage and convective flows is introduced to analyze the thermal/fluid behaviors in selective laser sintering of single powder layer. The model is also applied to investigate the sintering of powders on top of existing sintered layers under single- multiple-line scanning manners according to the practical manufacturing processes.

  16. Thermally induced light-scattering effects as responsible for the degradation of cholesteric liquid crystal lasers.

    Science.gov (United States)

    Etxebarria, J; Ortega, J; Folcia, C L; Sanz-Enguita, G; Aramburu, I

    2015-04-01

    We have studied the degradation process of the laser emission in a cholesteric liquid crystal laser. We have found that there exists a negative correlation between the laser efficiency and the amount of light scattered by the liquid-crystal sample in the illuminated area. The growth of scattering is attributed to the appearance of small imperfections generated in the sample as a result of certain thermal processes that involve the dye molecules. The scattering implies an increase of the coefficient of distributed losses, which is the main response of the rise of the laser threshold.

  17. Basic studies on intravascular low-intensity laser therapy

    Science.gov (United States)

    Liu, Timon Cheng-Yi; Duan, Rui; Wang, Shuang-Xi; Liu, Jiang; Cui, Li-Ping; Jin, Hua; Liu, Song-Hao

    2006-09-01

    Intravascular low intensity laser therapy (ILILT) was originally put forward in USA in 1982, but popularized in Russia in 1980s and in China in 1990s, respectively. A randomized placebo-controlled study has shown ILILT clinical efficacy in patients suffering from rheumatoid arthritis. As Chinese therapeutic applications of ILILT were the most widely in the world, its basic research, such as intracellular signal transduction research, blood research in vitro, animal blood research in vivo, human blood research in vivo and traditional Chinese medicine research, was also very progressive in China. Its basic studies will be reviewed in terms of the biological information model of photobiomodulation in this paper. ILILT might work in view of its basic studies, but the further randomized placebo-controlled trial and the further safety research should be done.

  18. Low level laser therapy on injured rat muscle

    Science.gov (United States)

    Mantineo, M.; Pinheiro, J. P.; Morgado, A. M.

    2013-06-01

    Although studies show the clinical effectiveness of low level laser therapy (LLLT) in facilitating the muscle healing process, scientific evidence is still required to prove the effectiveness of LLLT and to clarify the cellular and molecular mechanisms triggered by irradiation. Here we evaluate the effect of different LLLT doses, using continuous illumination (830 nm), in the treatment of inflammation induced in the gastrocnemius muscle of Wistar rats, through the quantification of cytokines in systemic blood and histological analysis of muscle tissue. We verified that all applied doses produce an effect on reducing the number of inflammatory cells and the concentration of pro-inflammatory TNF-α and IL-1β cytokines. The best results were obtained for 40 mW. The results may suggest a biphasic dose response curve.

  19. Endoscopic photodynamic therapy of tumors using gold vapor laser

    Science.gov (United States)

    Kuvshinov, Yury P.; Poddubny, Boris K.; Mironov, Andrei F.; Ponomarev, Igor V.; Shental, V. V.; Vaganov, Yu. E.; Kondratjeva, T. T.; Trofimova, E. V.

    1996-01-01

    Compact sealed-off gold vapor laser (GVL) with 2 W average power and 628 nm wavelength was used for endoscopic photodynamic therapy in 20 patients with different tumors in respiratory system and upper gastrointestinal tract. Russian-made hematoporphyrin derivative (Hpd) `Photohem' was used as a photosensitizer. It was given intravenously at a dose of 2 - 2.5 mg/kg body weight 48 hours prior to tumor illumination with 628 nm light from GVL. Intermittent irradiation with GVL was done through flexible endoscope always under local anaesthesia at a power of 200 - 400 mW/sm2 and a dose of 150 - 400 J/sm2. 80% patients showed complete or partial response depending on stage of tumor. In cases of early gastric cancer all patients had complete remission with repeated negative biopsies. No major complication occurred.

  20. Near-infrared dye loaded polymeric nanoparticles for cancer imaging and therapy and cellular response after laser-induced heating

    Directory of Open Access Journals (Sweden)

    Tingjun Lei

    2014-03-01

    Full Text Available Background: In the past decade, researchers have focused on developing new biomaterials for cancer therapy that combine imaging and therapeutic agents. In our study, we use a new biocompatible and biodegradable polymer, termed poly(glycerol malate co-dodecanedioate (PGMD, for the synthesis of nanoparticles (NPs and loading of near-infrared (NIR dyes. IR820 was chosen for the purpose of imaging and hyperthermia (HT. HT is currently used in clinical trials for cancer therapy in combination with radiotherapy and chemotherapy. One of the potential problems of HT is that it can up-regulate hypoxia-inducible factor-1 (HIF-1 expression and enhance vascular endothelial growth factor (VEGF secretion.Results: We explored cellular response after rapid, short-term and low thermal dose laser-IR820-PGMD NPs (laser/NPs induced-heating, and compared it to slow, long-term and high thermal dose heating by a cell incubator. The expression levels of the reactive oxygen species (ROS, HIF-1 and VEGF following the two different modes of heating. The cytotoxicity of NPs after laser/NP HT resulted in higher cell killing compared to incubator HT. The ROS level was highly elevated under incubator HT, but remained at the baseline level under the laser/NP HT. Our results show that elevated ROS expression inside the cells could result in the promotion of HIF-1 expression after incubator induced-HT. The VEGF secretion was also significantly enhanced compared to laser/NP HT, possibly due to the promotion of HIF-1. In vitro cell imaging and in vivo healthy mice imaging showed that IR820-PGMD NPs can be used for optical imaging.Conclusion: IR820-PGMD NPs were developed and used for both imaging and therapy purposes. Rapid and short-term laser/NP HT, with a low thermal dose, does not up-regulate HIF-1 and VEGF expression, whereas slow and long term incubator HT, with a high thermal dose, enhances the expression of both transcription factors.

  1. Low level laser therapy reduces inflammation in activated Achilles tendinitis

    Science.gov (United States)

    Bjordal, Jan M.; Iversen, Vegard; Lopes-Martins, Rodrigo Alvaro B.

    2006-02-01

    Objective: Low level laser therapy (LLLT) has been forwarded as therapy for osteoarthritis and tendinopathy. Results in animal and cell studies suggest that LLLT may act through a biological mechanism of inflammatory modulation. The current study was designed to investigate if LLLT has an anti-inflammatory effect on activated tendinitis of the Achilles tendon. Methods: Seven patients with bilateral Achilles tendonitis (14 tendons) who had aggravated symptoms by pain-inducing activity immediately prior to the study. LLLT (1.8 Joules for each of three points along the Achilles tendon with 904nm infrared laser) and placebo LLLT were administered to either Achilles tendons in a random order to which patients and therapist were blinded. Inflammation was examined by 1) mini-invasive microdialysis for measuring the concentration of inflammatory marker PGE II in the peritendinous tissue, 2) ultrasound with Doppler measurement of peri- and intratendinous blood flow, 3) pressure pain algometry and 4) single hop test. Results: PGE 2- levels were significantly reduced at 75, 90 and 105 minutes after active LLLT compared both to pre-treatment levels (p=0.026) and to placebo LLLT (p=0.009). Changes in pressure pain threshold (PPT) were significantly different (P=0.012) between groups. PPT increased by a mean value of 0.19 kg/cm2 [95%CI:0.04 to 0.34] after treatment in the active LLLT group, while pressure pain threshold was reduced by -0.20 kg/cm2 [95%CI:-0.45 to 0.05] after placebo LLLT. Conclusion: LLLT can be used to reduce inflammatory musculskeletal pain as it reduces inflammation and increases pressure pain threshold levels in activity-induced pain episodes of Achilles tendinopathy.

  2. In vitro transdentinal effect of low-level laser therapy

    Science.gov (United States)

    Oliveira, C. F.; Basso, F. G.; dos Reis, R. I.; Parreiras-e-Silva, L. T.; Lins, E. C.; Kurachi, C.; Hebling, J.; Bagnato, V. S.; de Souza Costa, C. A.

    2013-05-01

    Low-level laser therapy (LLLT) has been used for the treatment of dentinal hypersensitivity. However, the specific LLL dose and the response mechanisms of these cells to transdentinal irradiation have not yet been demonstrated. Therefore, this study evaluated the transdentinal effects of different LLL doses on stressed odontoblast-like pulp cells MDPC-23 seeded onto the pulpal side of dentin discs obtained from human third molars. The discs were placed in devices simulating in vitro pulp chambers and the whole set was placed in 24-well plates containing plain culture medium (DMEM). After 24 h incubation, the culture medium was replaced by fresh DMEM supplemented with either 5% (simulating a nutritional stress condition) or 10% fetal bovine serum (FBS). The cells were irradiated with doses of 15 and 25 J cm-2 every 24 h, totaling three applications over three consecutive days. The cells in the control groups were removed from the incubator for the same times as used in their respective experimental groups for irradiation, though without activating the laser source (sham irradiation). After 72 h of the last active or sham irradiation, the cells were evaluated with respect to succinic dehydrogenase (SDH) enzyme production (MTT assay), total protein (TP) expression, alkaline phosphatase (ALP) synthesis, reverse transcriptase polymerase chain reaction (RT-PCR) for collagen type 1 (Col-I) and ALP, and morphology (SEM). For both tests, significantly higher values were obtained for the 25 J cm-2 dose. Regarding SDH production, supplementation of the culture medium with 5% FBS provided better results. For TP and ALP expression, the 25 J cm-2 presented higher values, especially for the 5% FBS concentration (Mann-Whitney p laser irradiation at 25 J cm-2 caused transdentinal biostimulation of odontoblast-like MDPC-23 cells.

  3. Infantile hemangioma: pulsed dye laser versus surgical therapy

    Science.gov (United States)

    Remlova, E.; Dostalova, T.; Michalusova, I.; Vranova, J.; Jelinkova, H.; Hubacek, M.

    2014-05-01

    Hemangioma is a mesenchymal benign tumor formed by blood vessels. Anomalies affect up to 10% of children and they are more common in females than in males. The aim of our study was to compare the treatment efficacy, namely the curative effect and adverse events, such as loss of pigment and appearance of scarring, between classical surgery techniques and laser techniques. For that reason a group of 223 patients with hemangioma was retrospectively reviewed. For treatment, a pulsed dye laser (PDL) (Rhodamine G, wavelength 595 nm, pulsewidth between 0.45 and 40 ms, spot diameter 7 mm, energy density 9-11 J cm-2) was used and the results were compared with a control group treated with classical surgical therapy under general anesthesia. The curative effects, mainly number of sessions, appearance of scars, loss of pigment, and relapses were evaluated as a marker of successful treatment. From the results it was evident that the therapeutic effects of both systems are similar. The PDL was successful in all cases. The surgery patients had four relapses. Classical surgery is directly connected with the presence of scars, but the system is safe for larger hemangiomas. It was confirmed that the PDL had the optimal curative effect without scars for small lesions (approximately 10 mm). Surgical treatment under general anesthesia is better for large hemangiomas; the disadvantage is the presence of scars.

  4. Effects of low-level laser therapy on wound healing

    Directory of Open Access Journals (Sweden)

    Fabiana do Socorro da Silva Dias Andrade

    Full Text Available OBJECTIVE: To gather and clarify the actual effects of low-level laser therapy on wound healing and its most effective ways of application in human and veterinary medicine.METHODS: We searched original articles published in journals between the years 2000 and 2011, in Spanish, English, French and Portuguese languages, belonging to the following databases: Lilacs, Medline, PubMed and Bireme; Tey should contain the methodological description of the experimental design and parameters used.RESULTS: doses ranging from 3 to 6 J/cm2 appear to be more effective and doses 10 above J/cm2 are associated with deleterious effects. The wavelengths ranging from 632.8 to 1000 nm remain as those that provide more satisfactory results in the wound healing process.CONCLUSION: Low-level laser can be safely applied to accelerate the resolution of cutaneous wounds, although this fact is closely related to the election of parameters such as dose, time of exposure and wavelength.

  5. Comparison of the Effects of Low-Level Laser Therapy and Ozone Therapy on Bone Healing.

    Science.gov (United States)

    Alan, Hilal; Vardi, Nigar; Özgür, Cem; Acar, Ahmet Hüseyin; Hüseyin, Ahmet; Yolcu, Ümit; Doğan, Derya Ozdemir

    2015-07-01

    This study aims to compare the effect of low-level laser therapy (LLLT) and ozone therapy on the bone healing. Thirty-six adult male Wistar albino rats were used for this study. Monocortical defects were shaped in right femur of all rats. Defects were filled with nano-hydroxyapatite graft. The animals were divided into 3 groups and each group was than divided into 2 subgroups. Then, LLLT with a diode laser was applied to the first group (G1), ozone therapy was applied to the second group (G2), and no treatment was applied to the third group as a control group (G3). Animals were sacrificed after 4th and 8th weeks and the sections were examined to evaluate the density of the inflammation, the formation of connective tissue, the osteogenic potential, and osteocalcin activity. As a result, there were no significant differences among the groups of 4 weeks in terms of new bone formation. In the immunohistochemical assessment, the number of osteocalcin-positive cells was higher in the laser group compared to the other group of 4 weeks; this difference was statistically significant in the LLLT and ozone groups (P ozone groups; furthermore, there was a statistically significant difference in the LLLT in comparison with the control group at 8th week (P < 0.05). At the same time immunohistochemical assessment showed that osteocalcin-positive cells were considerably higher in G2 than G1 at 8th week (P < 0.05). The findings of this study may be the result of differences in the number of treatment sessions. Further studies are therefore needed to determine the optimal treatment modality.

  6. Analysis of thermal damage in vocal cords for the prevention of collateral laser treatment effects

    Science.gov (United States)

    Fanjul Vélez, Félix; Luis Arce-Diego, José; del Barrio Fernández, Ángela; Borragán Torre, Alfonso

    2007-05-01

    The importance of vocal cords for the interaction with the world around is obviously known. Vocal cords disorders can be divided mainly into three categories: difficulty of movement of one or both vocal folds, lesion formation on them, and difficulty or lack of mucosal wave movement. In this last case, a laser heating treatment can be useful in order to improve tissue vibration. However, thermal damage should be considered to adjust laser parameters and so to prevent irreversible harmful effects to the patient. in this work, an analysis of thermal damage in vocal folds is proposed. Firstly thermo-optical laser-tissue interaction is studied, by means of a RTT (Radiation Transfer Theory) model solved with a Monte Carlo approach for the optical propagation of radiation, and a bio-heat equation, with a finite difference numerical method based solution, taking into account blood perfusion and boundary effects, for the thermal distribution. The spatial-temporal temperature distributions are obtained for two widely used lasers, Nd:YAG (1064 nm) and KTP (532 nm). From these data, an Arrhenius thermal damage analysis allows a prediction of possible laser treatment harmful effects on vocal cords that could cause scar formation or tissue burn. Different source powers and exposition times are considered, in such a way that an approximation of adequate wavelength, power and duration is achieved, in order to implement an efficient and safe laser treatment.

  7. Thermal effects in high-power Nd:YAG disk-type solid state laser

    Science.gov (United States)

    Yang, Huomu; Feng, Guoying; Zhou, Shouhuan

    2011-09-01

    An investigation of thermal effects in a high-power Nd:YAG disk-type solid state laser pumped with different pump beam transverse profiles is carried out by numerical simulation based on the finite element method (FEM). Impact of the heat sink on the thermal effects is included in the simulation. The distribution of first principle stress, thermally induced birefringence, including the distribution and variation of the birefringence loss, are studied. The characteristics of the phase variation are analyzed with consideration of the temperature gradient, deformation, strain and thermal stress. Thermal lensing is explored as a function of pump power and of the radius pumped with different pump beam transverse profiles. The non-parabolic part of optical phase distortion is simulated. Furthermore, the characteristics of the bi-focus of the disk laser are also studied. Experiments on the maximum tensile stress distribution and depolarization loss are carried out. The presented calculations are in qualitative agreement with the experimental observations.

  8. A novel intelligent adaptive control of laser-based ground thermal test

    Directory of Open Access Journals (Sweden)

    Gan Zhengtao

    2016-08-01

    Full Text Available Laser heating technology is a type of potential and attractive space heat flux simulation technology, which is characterized by high heating rate, controlled spatial intensity distribution and rapid response. However, the controlled plant is nonlinear, time-varying and uncertainty when implementing the laser-based heat flux simulation. In this paper, a novel intelligent adaptive controller based on proportion–integration–differentiation (PID type fuzzy logic is proposed to improve the performance of laser-based ground thermal test. The temperature range of thermal cycles is more than 200 K in many instances. In order to improve the adaptability of controller, output scaling factors are real time adjusted while the thermal test is underway. The initial values of scaling factors are optimized using a stochastic hybrid particle swarm optimization (H-PSO algorithm. A validating system has been established in the laboratory. The performance of the proposed controller is evaluated through extensive experiments under different operating conditions (reference and load disturbance. The results show that the proposed adaptive controller performs remarkably better compared to the conventional PID (PID controller and the conventional PID type fuzzy (F-PID controller considering performance indicators of overshoot, settling time and steady state error for laser-based ground thermal test. It is a reliable tool for effective temperature control of laser-based ground thermal test.

  9. Numerical analysis of thermal deformation in laser beam heating of a steel plate

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chao; Kim, Yong-Rae; Kim, Jae-Woong [Yeungnam University, Kyongsan (Korea, Republic of)

    2017-05-15

    Line heating is a widely used process for plate forming or thermal straightening. Flame heating and induction heating are the traditional heating processes used by industry for line heating. However, these two heating processes are ineffective when used on small steel plates. Thus, the laser beam heating with various power profiles were carried out in this study. A comparison of numerical simulation results and experimental results found a significant difference in the thermal deformation when apply a different power profile of laser beam heating. The one-sinusoid power profile produced largest thermal deformation in this study. The laser beam heating process was simulated by established a combined heat source model, and simulated results were compared with experimental results to confirm the model’s accuracy. The mechanism of thermal deformation was investigated and the effects of model parameters were studied intensively with the finite element method. Thermal deformation was found to have a significant relationship with the amount of central zone plastic deformation. Scientists and engineers could use this study’s verified model to select appropriate parameters in laser beam heating process. Moreover, by using the developed laser beam model, the analysis of welding residual stress or hardness could also be investigated from a power profile point of view.

  10. A novel intelligent adaptive control of laser-based ground thermal test

    Institute of Scientific and Technical Information of China (English)

    Gan Zhengtao; Yu Gang; Li Shaoxia; He Xiuli; Chen Ru; Zheng Caiyun; Ning Weijian

    2016-01-01

    Laser heating technology is a type of potential and attractive space heat flux simulation technology, which is characterized by high heating rate, controlled spatial intensity distribution and rapid response. However, the controlled plant is nonlinear, time-varying and uncertainty when implementing the laser-based heat flux simulation. In this paper, a novel intelligent adaptive controller based on proportion–integration–differentiation (PID) type fuzzy logic is proposed to improve the performance of laser-based ground thermal test. The temperature range of thermal cycles is more than 200 K in many instances. In order to improve the adaptability of controller, output scaling factors are real time adjusted while the thermal test is underway. The initial values of scaling factors are optimized using a stochastic hybrid particle swarm optimization (H-PSO) algorithm. A validating system has been established in the laboratory. The performance of the pro-posed controller is evaluated through extensive experiments under different operating conditions (reference and load disturbance). The results show that the proposed adaptive controller performs remarkably better compared to the conventional PID (PID) controller and the conventional PID type fuzzy (F-PID) controller considering performance indicators of overshoot, settling time and steady state error for laser-based ground thermal test. It is a reliable tool for effective temperature control of laser-based ground thermal test.

  11. Thermal transport in CO2 laser irradiated fused silica: In situ measurements and analysis

    Science.gov (United States)

    Yang, Steven T.; Matthews, Manyalibo J.; Elhadj, Selim; Draggoo, Vaughn G.; Bisson, Scott E.

    2009-11-01

    In situ spatial and temporal temperature measurements of pristine fused silica surfaces heated with a 10.6 μm CO2 laser were obtained using an infrared radiation thermometer based on a mercury cadmium telluride camera. Laser spot sizes ranged from 250 to 1000 μm diameter with peak axial irradiance levels of 0.13-16 kW/cm2. For temperatures below 2800 K, the measured steady-state surface temperature is observed to rise linearly with both increasing beam size and incident laser irradiance. The effective thermal conductivity estimated over this range was approximately 2 W/m-K, in good agreement with classical calculations based on phonon heat capacities. Similarly, time-dependent temperature measurements up to 2000 K yielded thermal diffusivity values which were close to reported values of 7×10-7 m2/s. Above ˜2800 K, the fused silica surface temperature asymptotically approaches 3100 K as laser power is further increased, consistent with the onset of evaporative heat losses near the silica boiling point. These results show that in the laser heating regime studied here, the T3 temperature dependent thermal conductivity due to radiation transport can be neglected, but at temperatures above 2800 K heat transport due to evaporation must also be considered. The thermal transport in fused silica up to 2800 K, over a range of conditions, can then be adequately described by a linear diffusive heat equation assuming constant thermal properties.

  12. Thermal character in organic polymers with nanojoule femtosecond laser ablation

    Institute of Scientific and Technical Information of China (English)

    Xiaochang Ni(倪晓昌); Ching-Yue Wang(王清月); Yanfeng Li(栗岩峰); Minglie Hu(胡明列); Zhuan Wang(王专); Lu Chai(柴路)

    2003-01-01

    Ablation experiments with femtosecond (fs) laser pulse (pulse duration 37 fs, wavelength 800 nm) on organic polymers have been performed in air. The ablation threshold is found to be only several nanojoules. The diameters of the dots ablated in the organic polymers are influenced by the laser fluence and the number of laser pulses. It is observed that heat is diffused in a threadlike manner in all directions around the central focus region. Explanations of the observed phenomena are presented. A one-dimensional waveguide is also ablated in the organic polymers.

  13. Laser-Based Strategies to Treat Diabetic Macular Edema: History and New Promising Therapies

    Directory of Open Access Journals (Sweden)

    Young Gun Park

    2014-01-01

    Full Text Available Diabetic macular edema (DME is the main cause of visual impairment in diabetic patients. The management of DME is complex and often various treatment approaches are needed. At the present time, despite the enthusiasm for evaluating several new treatments for DME, including the intravitreal pharmacologic therapies (e.g., corticosteroids and anti-VEGF drugs, laser photocoagulation still remains the current standard in DME. The purpose of this review is to update our knowledge on laser photocoagulation for DME and describe the developments in laser systems. And we will also discuss the new laser techniques and review the latest results including benefits of combined therapy. In this paper, we briefly summarize the major laser therapeutics for the treatment of diabetic macular edema and allude to some future promising laser therapies.

  14. Laser therapy for Hailey-Hailey Disease: review of the literature and a case report

    Directory of Open Access Journals (Sweden)

    Arisa E. Ortiz

    2011-10-01

    Full Text Available Medical therapy for Hailey-Hailey disease (HHD generally only provides temporary suppression. Surgical intervention has been shown to prolong remission, but may lead to significant morbidity. Laser therapy is becoming the preferred method of treatment because of its successful results and lower risk of complications compared to surgical modalities. We report a case of fractional ablative carbon dioxide (CO2 laser treatment for HHD and review the relevant literature. Fractional CO2 laser therapy was performed in our patient with a 14-year history of HHD. No recurrence was observed 5 months after laser therapy in right inframammary and axillary regions. Symptomatic recurrence was noted after treatment of inguinal areas. In conclusion, traditional laser ablation remains the treatment of choice for prolonged remission of recalcitrant plaques in HHD.

  15. Monitoring of thermal therapy based on shear modulus changes: II. Shear wave imaging of thermal lesions.

    Science.gov (United States)

    Arnal, Bastien; Pernot, Mathieu; Tanter, Mickael

    2011-08-01

    The clinical applicability of high-intensity focused ultrasound (HIFU) for noninvasive therapy is currently hampered by the lack of robust and real-time monitoring of tissue damage during treatment. The goal of this study is to show that the estimation of local tissue elasticity from shear wave imaging (SWI) can lead to a precise mapping of the lesion. HIFU treatment and monitoring were respectively performed using a confocal setup consisting of a 2.5-MHz single element transducer focused at 34 mm on ex vivo samples and an 8-MHz ultrasound diagnostic probe. Ultrasound-based strain imaging was combined with shear wave imaging on the same device. The SWI sequences consisted of 2 successive shear waves induced at different lateral positions. Each wave was created with pushing beams of 100 μs at 3 depths. The shear wave propagation was acquired at 17,000 frames/s, from which the elasticity map was recovered. HIFU sonications were interleaved with fast imaging acquisitions, allowing a duty cycle of more than 90%. Thus, elasticity and strain mapping was achieved every 3 s, leading to real-time monitoring of the treatment. When thermal damage occurs, tissue stiffness was found to increase up to 4-fold and strain imaging showed strong shrinkages that blur the temperature information. We show that strain imaging elastograms are not easy to interpret for accurate lesion characterization, but SWI provides a quantitative mapping of the thermal lesion. Moreover, the concept of shear wave thermometry (SWT) developed in the companion paper allows mapping temperature with the same method. Combined SWT and shear wave imaging can map the lesion stiffening and temperature outside the lesion, which could be used to predict the eventual lesion growth by thermal dose calculation. Finally, SWI is shown to be robust to motion and reliable in vivo on sheep muscle.

  16. New approaches in light/laser therapies and photodynamic treatment of acne.

    Science.gov (United States)

    Piérard-Franchimont, Claudine; Paquet, Philippe; Piérard, Gérald E

    2011-03-01

    Acne is a domain in which the technology and understanding of light/laser therapeutic procedures have advanced considerably. The aim of the paper was to revisit adjunctive physical treatments of acne, including light/laser treatments and photodynamic therapy. This review summarizes findings about such treatment modalities with particular emphasis on efficacy and safety. A number of laser/light-based modalities have been developed to meet the increasing demand for new acne treatments. The current devices correspond, on the one hand, to light-emitting diode therapy and, on the other hand, to the 532-nm potassium titanyl phosphate laser, the 585- and 595-nm pulsed dye laser, the 1450-nm diode laser, the 1320-nm Nd:YAG laser and intense pulsed light. Photodynamic therapy is also available. It is claimed that light/laser treatments might induce a faster response compared with the 1-3 months needed for response to traditional oral and topical treatments. In conclusion, pulsed dye laser shows efficacy in some patients with mild to moderate acne. The relative effectiveness compared with other treatments is unconfirmed; from the published information, evidence-based efficacy assessment of light/laser therapies in acne remains almost impossible.

  17. Endoscopic Ho laser interstitial therapy for pharyngolaryngeal venous malformations in adults.

    Science.gov (United States)

    Xiuwen, Jiang; Jianguo, Tang

    2015-04-01

    Many methods have been used to treat venous malformations, including sclerotherapy, laser therapy, and surgery. Nowadays, endoscopic laser surgery has become a popular therapeutic modality for most of pharyngolaryngeal venous malformations. There are various kinds of lasers that have been applied, but Holmium:YAG laser (Ho laser) has not been reported yet. Ho laser is produced by a kind of iraser which is made of yttrium aluminum garnet mixed with holmium, chromium and thulium. Aim of the current work is to evaluate the efficacy and safety of Ho laser interstitial therapy in pharyngolaryngeal venous malformations in adults. The clinical data of 42 patients with pharyngolaryngeal venous malformation treated with endoscopic Ho laser interstitial therapy over a 12-year period were retrospectively reviewed and analyzed. The wave length of Ho laser was 2.1 µm and the diameter of optical fiber was 550 µm. The pulse energy was 0.5 J and the time of duration was 600 µs. The highest output power was 100 W. Outcomes were graded as cure (complete resolution), considerable reduction (>60-80 % reduction), and no obvious change (laser interstitial therapy is an effective and safe treatment modality for pharyngolaryngeal venous malformations in adults.

  18. A 1,470 nm diode laser in stapedotomy: Mechanical, thermal, and acoustic effects.

    Science.gov (United States)

    Koenraads, Simone P C; de Boorder, Tjeerd; Grolman, Wilko; Kamalski, Digna M A

    2017-08-01

    Multiple laser systems have been investigated for their use in stapes surgery in patients with otosclerosis. The diode 1,470 nm laser used in this study is an attractive laser system because it is easily transported and relatively inexpensive in use. This wavelength has relative high absorption in water. This study aimed to investigate the mechanical, thermal, and acoustic effects of the diode 1,470 nm laser on a stapes in an inner ear model. Experiments were performed in an inner ear model including fresh frozen human stapes. High-speed imaging with frame rates up to 2,000 frames per second (f/s) was used to visualize the effects in the vestibule during fenestration of the footplate. A special high-speed color Schlieren technique was used to study thermal effects. The sound produced by perforation was recorded by a hydrophone. Single pulse settings of the diode 1,470 nm laser were 100 ms, 3 W. Diode 1,470 nm laser fenestration showed mechanical effects with small vapor bubbles and pressure waves pushed into the vestibule. Thermal imaging visualized an increase temperature underneath the stapes footplate. Acoustic effects were limited, but larger sounds levels were reached when vaporization bubbles arise and explode in the vestibule. The diode 1,470 nm laser highly absorbs in perilymph and is capable of forming a clear fenestration in the stapes. An overlapping laser pulse will increase the risk of vapor bubbles, pressure waves, and heating the vestibule. As long as we do not know the possible damage of these effects to the inner ear function, it seems advisable to use the laser with less potential harm. Lasers Surg. Med. 49:619-624, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  19. Residual Stress Analysis of Laser-Drilled Thermal Barrier Coatings Involving Various Bond Coats

    Science.gov (United States)

    Guinard, C.; Montay, G.; Guipont, V.; Jeandin, M.; Girardot, J.; Schneider, M.

    2015-01-01

    The gas turbine combustion chamber of aero-engines requires a thermal barrier coating (TBC) by thermal spraying. Further heat protection is achieved by laser drilling of cooling holes. The residual stresses play an important role in the mechanical behaviour of TBC. It could also affect the TBC response to delamination during laser drilling. In this work, studies of the cracking behaviour after laser drilling and residual stress distribution have been achieved for different bond coats by plasma spray or cold spray. From interface crack length measured pulse-by-pulse after laser percussion drilling at 20° angle, the role of the various bond coats on crack initiation and propagation are investigated. It is shown that the bond coat drastically influences the cracking behaviour. The residual stresses profiles were also determined by the incremental hole-drilling method involving speckle interferometry. An original method was also developed to measure the residual stress profiles around a pre-drilled zone with a laser beam at 90°. The results are discussed to highlight the influence of TBCs interfaces on the resulting residual stresses distribution before laser drilling, and also to investigate the modification around the hole after laser drilling. It is shown that laser drilling could affect the residual stress state.

  20. Thermal and molecular investigation of laser tissue welding

    Energy Technology Data Exchange (ETDEWEB)

    Small, W., IV

    1998-06-01

    Despite the growing number of successful animal and human trials, the exact mechanisms of laser tissue welding remain unknown. Furthermore, the effects of laser heating on tissue on the molecular scale are not fully understood. To address these issues, a multi-front attack oil both extrinsic (solder/patch mediated) and intrinsic (laser only) tissue welding was launched using two-color infrared thermometry, computer modeling, weld strength assessment, biochemical assays, and vibrational spectroscopy. The coupling of experimentally measured surface temperatures with the predictive numerical simulations provided insight into the sub-surface dynamics of the laser tissue welding process. Quantification of the acute strength of the welds following the welding procedure enabled comparison among trials during an experiment, with previous experiments, and with other studies in the literature. The acute weld integrity also provided an indication of tile probability of long-term success. Molecular effects induced In the tissue by laser irradiation were investigated by measuring tile concentrations of specific collagen covalent crosslinks and characterizing the Fourier-Transform infrared (FTIR) spectra before and after the laser exposure.

  1. Pulsed delivery of laser energy in experimental thermal retinal photocoagulation

    Science.gov (United States)

    Pankratov, Michail M.

    1990-06-01

    Retinal lesions produced with a pulsed laser beam of 1-20 kHz frequency and 10-100% duty cycle were compared with lesions produced with a continuous wave (cw) laser of the same peak power and total energy. Photocoagulation was applied to the retina of three black pigmented rabbits using krypton red laser (647.1 nm) equipped with an acousto-optical modulator to convert cw laser emission to a pulsating beam. An optical fiber fed the laser beam into an optical system delivering a collimated beam of predetermined divergence; the animal's eye focused this beam to a 50-pm spot on the retina. Peak power was kept constant at 0.2 W, and energy was kept constant at 20 mJ. After 7 months the animals were sacrificed and retinal tissue examined by light microscopy. The central section of each lesion was identified and photographed. For lesions with the same energy per pulse and the same pulse duration, the most influential factor, in the frequency range of 1-20 kHz, appeared to be the duty cycle: the smaller the duty cycle, the smaller the lesion, and vice versa. In other words, the shorter the time interval between consecutive pulses, the larger were the pulsed laser lesions.

  2. Design of a Novel Servo-motorized Laser Device for Visual Pathways Diseases Therapy

    Directory of Open Access Journals (Sweden)

    Carlos Ignacio Sarmiento

    2015-12-01

    Full Text Available We discuss a novel servo-motorized laser device and a research protocol for visual pathways diseases therapies. The proposed servo-mechanized laser device can be used for potential rehabilitation of patients with hemianopia, quadrantanopia, scotoma, and some types of cortical damages. The device uses a semi spherical structure where the visual stimulus will be shown inside, according to a previous stimuli therapy designed by an ophthalmologist or neurologist. The device uses a pair of servomotors (with torque=1.5kg, which controls the laser stimuli position for the internal therapy and another pair for external therapy. Using electronic tools such as microcontrollers along with miscellaneous electronic materials, combined with LabVIEW based interface, a control mechanism is developed for the new device. The proposed device is well suited to run various visual stimuli therapies. We outline the major design principles including the physical dimensions, laser device’s kinematical analysis and the corresponding software development.

  3. Design of a Novel Servo-motorized Laser Device for Visual Pathways Diseases Therapy

    Directory of Open Access Journals (Sweden)

    Carlos Ignacio Sarmiento

    2015-12-01

    Full Text Available We discuss a novel servo-motorized laser device and a research protocol for visual pathways diseases therapies. The proposed servo-mechanized laser device can be used for potential rehabilitation of patients with hemianopia, quadrantanopia, scotoma, and some types of cortical damages. The device uses a semi spherical structure where the visual stimulus will be shown inside, according to a previous stimuli therapy designed by an ophthalmologist or neurologist. The device uses a pair of servomotors (with torque=1.5kg, which controls the laser stimuli position for the internal therapy and another pair for external therapy. Using electronic tools such as microcontrollers along with miscellaneous electronic materials, combined with LabVIEW based interface, a control mechanism is developed for the new device. The proposed device is well suited to run various visual stimuli therapies. We outline the major design principles including the physical dimensions, laser device’s kinematical analysis and the corresponding software development.

  4. Thermal investigation on high power dfb broad area lasers at 975 nm, with 60% efficiency

    Science.gov (United States)

    Mostallino, R.; Garcia, M.; Deshayes, Y.; Larrue, A.; Robert, Y.; Vinet, E.; Bechou, L.; Lecomte, M.; Parillaud, O.; Krakowski, M.

    2016-03-01

    The demand of high power diode lasers in the range of 910-980nm is regularly growing. This kind of device for many applications, such as fiber laser pumping [1], material processing [1], solid-state laser pumping [1], defense and medical/dental. The key role of this device lies in the efficiency (𝜂𝐸) of converting input electrical power into output optical power. The high value of 𝜂𝐸 allows high power level and reduces the need in heat dissipation. The requirement of wavelength stabilization with temperature is more obvious in the case of multimode 975nm diode lasers used for pumping Yb, Er and Yb/Er co-doped solid-state lasers, due to the narrow absorption line close to this wavelength. Such spectral width property (new measurement based on the pulse electrical method and using the T3STERequipment. This method is well known for electronic devices and LEDs but is weakly developed for the high power diodes laser. This crucial measurement compared to spectral one is critical for understand the thermal management of diode laser device and improve the structure based on design for reliability. To have a perfect relation between structure, and their modification, and temperature, FEM simulations are performed using COMSOL software. In this case, we can understand the impact of structure on the isothermal distribution and then reveal the sensitive zones in the diode laser. To validate the simulation, we compare the simulation results to the experimental one and develop an analytical model to determine the different contributions of the thermal heating. This paper reports on the development laser structure and the process techniques required to write the gratings. Performances are particularly characterized in terms of experimental electro-optical characterization and spectral response. The extraction of thermal resistance (Rth) is particularly difficult, because of the implicit low value (Rth ≈ 2𝐾/𝑊) and the multimodal

  5. The effects of laser repetition rate on femtosecond laser ablation of dry bone: a thermal and LIBS study.

    Science.gov (United States)

    Gill, Ruby K; Smith, Zachary J; Lee, Changwon; Wachsmann-Hogiu, Sebastian

    2016-01-01

    The aim of this study is to understand the effect of varying laser repetition rate on thermal energy accumulation and dissipation as well as femtosecond Laser Induced Breakdown Spectroscopy (fsLIBS) signals, which may help create the framework for clinical translation of femtosecond lasers for surgical procedures. We study the effect of repetition rates on ablation widths, sample temperature, and LIBS signal of bone. SEM images were acquired to quantify the morphology of the ablated volume and fsLIBS was performed to characterize changes in signal intensity and background. We also report for the first time experimentally measured temperature distributions of bone irradiated with femtosecond lasers at repetition rates below and above carbonization conditions. While high repetition rates would allow for faster cutting, heat accumulation exceeds heat dissipation and results in carbonization of the sample. At repetition rates where carbonization occurs, the sample temperature increases to a level that is well above the threshold for irreversible cellular damage. These results highlight the importance of the need for careful selection of the repetition rate for a femtosecond laser surgery procedure to minimize the extent of thermal damage to surrounding tissues and prevent misclassification of tissue by fsLIBS analysis.

  6. The thermal impact of phototherapy with concurrent super-pulsed lasers and red and infrared LEDs on human skin.

    Science.gov (United States)

    Grandinétti, Vanessa dos Santos; Miranda, Eduardo Foschini; Johnson, Douglas Scott; de Paiva, Paulo Roberto Vicente; Tomazoni, Shaiane Silva; Vanin, Adriane Aver; Albuquerque-Pontes, Gianna Móes; Frigo, Lucio; Marcos, Rodrigo Labat; de Carvalho, Paulo de Tarso Camillo; Leal-Junior, Ernesto Cesar Pinto

    2015-07-01

    From the very first reports describing the method of action of phototherapy, the effects have been considered to be the result of photochemical and photophysical interactions between the absorbed photons and tissue and not related to secondary changes in tissue or skin temperature. However, thermal effects have been recently reported in dark pigmented skin when irradiated with single wavelengths of 810 and 904 nm of low-level laser therapy (LLLT) devices even with doses that do not exceed those recommended by the World Association of Laser Therapy (WALT). The aim of this study was to evaluate the thermal impact during the concurrent use of pulsed red and infrared LEDs and super-pulsed lasers when applied to light, medium, and dark pigmented human skin with doses typically seen in clinical practice. The study evaluated the skin temperature of 42 healthy volunteers (males and females 18 years or older, who presented different pigmentations, stratified according to Von Luschan's chromatic scale) via the use of a thermographic camera. Active irradiation was performed with using the multi-diode phototherapy cluster containing four 905-nm super-pulsed laser diodes (frequency set to 250 Hz), four 875-nm infrared-emitting diodes, and four 640-nm LEDs (manufactured by Multi Radiance Medical™, Solon, OH, USA). Each of the four doses were tested on each subject: placebo, 0 J (60 s); 10 J (76 s); 30 J (228 s); and 50 J (380 s). Data were collected during the last 5 s of each dose of irradiation and continued for 1 min after the end of each irradiation. No significant skin temperature increases were observed among the different skin color groups (p > 0.05), age groups (p > 0.05), or gender groups (p > 0.05). Our results indicate that the concurrent use of super-pulsed lasers and pulsed red and infrared LEDs can be utilized in patients with all types of skin pigmentation without concern over safety or excessive tissue heating. Additionally, the doses

  7. Noncontacting Laser Inspection System for Dimensional Profiling of Space Application Thermal Barriers

    Science.gov (United States)

    Taylor, Shawn C.

    2011-01-01

    A noncontacting, two-dimensional (2-D) laser inspection system has been designed and implemented to dimensionally profile thermal barriers being developed for space vehicle applications. In a vehicle as-installed state, thermal barriers are commonly compressed between load sensitive thermal protection system (TPS) panels to prevent hot gas ingestion through the panel interface during flight. Loads required to compress the thermal barriers are functions of their construction, as well as their dimensional characteristics relative to the gaps in which they are installed. Excessive loads during a mission could damage surrounding TPS panels and have catastrophic consequences. As such, accurate dimensional profiling of thermal barriers prior to use is important. Due to the compliant nature of the thermal barriers, traditional contact measurement techniques (e.g., calipers and micrometers) are subjective and introduce significant error and variability into collected dimensional data. Implementation of a laser inspection system significantly enhanced the method by which thermal barriers are dimensionally profiled, and improved the accuracy and repeatability of collected data. A statistical design of experiments study comparing laser inspection and manual caliper measurement techniques verified these findings.

  8. Minimally invasive non-thermal laser technology using laser-induced optical breakdown for skin rejuvenation

    NARCIS (Netherlands)

    Habbema, L.; Verhagen, R.; Van Hal, R.; Liu, Y.; Varghese, B.

    2011-01-01

    We describe a novel, minimally invasive laser technology for skin rejuvenation by creating isolated microscopic lesions within tissue below the epidermis using laser induced optical breakdown. Using an in-house built prototype device, tightly focused near-infrared laser pulses are used to create opt

  9. Minimally invasive non-thermal laser technology using laser-induced optical breakdown for skin rejuvenation

    NARCIS (Netherlands)

    Habbema, L.; Verhagen, R.; Van Hal, R.; Liu, Y.; Varghese, B.

    2011-01-01

    We describe a novel, minimally invasive laser technology for skin rejuvenation by creating isolated microscopic lesions within tissue below the epidermis using laser induced optical breakdown. Using an in-house built prototype device, tightly focused near-infrared laser pulses are used to create

  10. Non-thermal ablation of expanded polytetrafluoroethylene with an intense femtosecond-pulse laser

    OpenAIRE

    Hashida, M.; Mishima, H.; Tokita, S.; Sakabe, S.

    2009-01-01

    Ablation of expanded polytetrafluoroethylene without disruption of the fine porous structure is demonstrated using an intense femtosecond-pulse laser. As a result of laser-matter interactions near ablation threshold fluence, high-energy ions are emitted, which cannot be produced by thermal dissociation of the molecules. The ion energy is produced by Coulomb explosion of the elements of (-CF_{2}-CF_{2-})n and the energy spectra of the ions show contributions from the Coulomb explosions of the ...

  11. Analytical modelling of end thermal coupling in a solid-state laser longitudinally bonded by a vertical-cavity top-emitting laser diode

    Institute of Scientific and Technical Information of China (English)

    Wu Jian; H.D.Summers

    2009-01-01

    The intrinsic features involving a circularly symmetric beam profile with low divergence, planar geometry as well as the increasingly enhanced power of vertical-cavity surface-emitting lasers (VCSELs) have made the VCSEL a promising pump source in direct end bonding to a solid-state laser medium to form the minimized, on-wafer integrated laser system. This scheme will generate a surface contact pump configuration and thus additional end thermal coupling to the laser medium through the joint interface of both materials, apart from pump beam heating. This paper analytically models temperature distributions in both VCSEL and the laser medium from the end thermal coupling regarding surface contact pump configuration using a top-emitting VCSEL as the pump source for the first time. The analytical solutions are derived by introducing relative temperature and mean temperature expressions. The results show that the end contact heating by the VCSEL could lead to considerable temperature variations associated with thermal phase shift and thermal lensing in the laser medium. However, if the central temperature of the interface is increased by less than 20 K, the end contact heating does not have a significant thermal influence on the laser medium. In this case, the thermal effect should be dominated by pump beam heating. This work provides useful analytical results for further analysis of hybrid thermal effects on those lasers pumped by a direct VCSEL bond.

  12. Optoacoustic monitoring of cutting efficiency and thermal damage during laser ablation.

    Science.gov (United States)

    Bay, Erwin; Douplik, Alexandre; Razansky, Daniel

    2014-05-01

    Successful laser surgery is characterized by a precise cut and effective hemostasis with minimal collateral thermal damage to the adjacent tissues. Consequently, the surgeon needs to control several parameters, such as power, pulse repetition rate, and velocity of movements. In this study we propose utilizing optoacoustics for providing the necessary real-time feedback of cutting efficiency and collateral thermal damage. Laser ablation was performed on a bovine meat slab using a Q-switched Nd-YAG laser (532 nm, 4 kHz, 18 W). Due to the short pulse duration of 7.6 ns, the same laser has also been used for generation of optoacoustic signals. Both the shockwaves, generated due to tissue removal, as well as the normal optoacoustic responses from the surrounding tissue were detected using a single broadband piezoelectric transducer. It has been observed that the rapid reduction in the shockwave amplitude occurs as more material is being removed, indicating decrease in cutting efficiency, whereas gradual decrease in the optoacoustic signal likely corresponds to coagulation around the ablation crater. Further heating of the surrounding tissue leads to carbonization accompanied by a significant shift in the optoacoustic spectra. Our results hold promise for real-time monitoring of cutting efficiency and collateral thermal damage during laser surgery. In practice, this could eventually facilitate development of automatic cut-off mechanisms that will guarantee an optimal tradeoff between cutting and heating while avoiding severe thermal damage to the surrounding tissues.

  13. Problems for determining the thermal conductivity of TBCs by laser-flash method

    Directory of Open Access Journals (Sweden)

    O. Altun

    2008-10-01

    Full Text Available Purpose: The purpose of this paper was to investigate the parameters which effect the results of determining the thermal conductivity of thermal barrier coatings (TBCs by laser-flash method.Design/methodology/approach: The air plasma-spray (APS technique was used to deposition of two- and three-layered samples. Two-layered samples were composed of metal substrate (321 stainless steel, and ceramic top coat (8YSZ. Three-layered samples were composed of metal substrate (321 stainless steel, bond coat (NiCrAlY and top coat (8YSZ. Thermal diffusivity of each layer have been measured in the temperature range from room temperature (RT to 900ºC by laser-flash method. The thermal conductivity was calculated with respect to density, specific heat and diffusivity of the materials.Findings: Obtained results show that the specific heat, density and thicknesses of metal substrate, bond coat and top coat play important role in the thermal conductivity measurement.Research limitations/implications: To obtain the correct results in laser-flash technique thickness, density, and cp of the materials are needed to be measured accurately and surface smoothness of samples should be provided sensitively. Errors in these parameters cause high deviations in measurements.Practical implications: It has been aimed offer an insight into the experimental determination of thermal conductivity of layered TBC system which are used in high technologic applications.Originality/value: Laser-flash method is the most widely used experimental technique to determine the thermal conductivity of APS TBCs at high temperatures. The research contributes to better understanding and recognition the importance of sample preparation in laser-flash method.

  14. Thermal properties of high-power diode lasers investigated by means of high resolution thermography

    Energy Technology Data Exchange (ETDEWEB)

    Kozlowska, Anna, E-mail: Anna.Kozlowska@itme.edu.pl [Institute of Electronic Materials Technology, 133 Wolczynska St., 01-919 Warsaw (Poland); Malag, Andrzej; Dabrowska, Elzbieta; Teodorczyk, Marian [Institute of Electronic Materials Technology, 133 Wolczynska St., 01-919 Warsaw (Poland)

    2012-09-01

    In the present work, thermal effects in high-power diode lasers are investigated by means of high resolution thermography. Thermal properties of the devices emitting in the 650 nm and 808 nm wavelength ranges are compared. The different versions of the heterostructure design are analyzed. The results show a lowering of active region temperature for diode lasers with asymmetric heterostructure scheme with reduced quantum well distance from the heterostructure surface (and the heat sink). Optimization of technological processes allowed for the improvement of the device performance, e.g. reduction of solder non-uniformities and local defect sites at the mirrors which was visualized by the thermography.

  15. Laser-induced thermal dynamics and temperature localization phenomenon in tissues and cells doped with nanoshells

    Science.gov (United States)

    Yakunin, Alexander N.; Avetisyan, Yury A.; Tuchin, Valery V.

    2012-03-01

    Paper presents and discusses the features of laser-induced thermal dynamics of the gold nanoshells, which is associated with their relatively large size and layered structure. Unlike bulk nanoparticles the existence of a novel thermal phenomenon - hoop-shaped narrow hot zone on the nanoshell surface - is found. It is caused by spatial-temporal inhomogeneities of light field diffracted by a nanoshell and corresponding absorption of laser radiation. The numerical solution of time-dependent heat conduction equation accounting for corresponding spatially inhomogeneous distribution of heating sources is presented.

  16. Laser cutting of Kevlar laminates and thermal stress formed at cutting sections

    Science.gov (United States)

    Yilbas, B. S.; Akhtar, S. S.

    2012-02-01

    Laser cutting of Kevlar laminates is carried out and thermal stress field developed in the cutting region is predicted using the finite element code. Temperature predictions are validated through the thermocouple data. The morphological changes in the cutting section are examined by incorporating optical and scanning electron microscopes. It is found that temperature predictions agree well with the thermocouple data. High values of von Mises stress are observed at the cutting edges and at the mid-thickness of the Kevlar laminate due to thermal compression formed in this region. The laser cut edges are free from whiskers; however, striation formation and some small sideways burning is observed at the kerf edges.

  17. Role of thermal diffusion in cw IR laser absorption in gas mixtures.

    Science.gov (United States)

    Maleissye, J T; Lempereur, F

    1982-01-15

    The absorption of radiation from a cw CO(2) laser by a mixture of absorbing SF(6) and transparent buffer gases has been measured as a function of pressure of added transparent gas (C(4)H(10)). The results are analyzed in terms of thermal diffusion of excited SF6 molecules out of the irradiation zone. In the 60-400-Torr pressure range, thermal difusion depletes the concentration of SF(6) so that the overall absorption is decreased and competes with the various channels of collisional relaxation which enhance absorption. An approximate semiempirical expression is used to determine the transient perturbation of concentration which occurs inside the laser beam.

  18. Effect of class IV laser therapy on chemotherapy-induced oral mucositis: a clinical and experimental study.

    Science.gov (United States)

    Ottaviani, Giulia; Gobbo, Margherita; Sturnega, Mauro; Martinelli, Valentina; Mano, Miguel; Zanconati, Fabrizio; Bussani, Rossana; Perinetti, Giuseppe; Long, Carlin S; Di Lenarda, Roberto; Giacca, Mauro; Biasotto, Matteo; Zacchigna, Serena

    2013-12-01

    Oral mucositis (OM) is a serious and acute side effect in patients with cancer who receive chemotherapy or radiotherapy, often leading to the suspension of therapy and a need for opioid analgesic and enteral/parenteral nutrition, with an effect on patient survival. Among the various interventions proposed in OM management, laser therapy is becoming a recommended treatment option but has limitations due to its heterogeneous laser parameters. Here, we report on our successful clinical experience on the use of class IV laser therapy to treat OM induced by different chemotherapy regimens. To shed light on the mechanisms of action of laser therapy in improving OM resolution, we have developed an animal model of chemotherapy-induced OM, in which we compare the efficacy of the standard low-power laser therapy protocol with an innovative protocol, defined as high-power laser therapy. We show that high-power laser therapy is more effective than low-power laser therapy in improving OM lesion healing, reducing the inflammatory burden, and preserving tissue integrity. In addition, high-power laser therapy has been particularly effective in promoting the formation of new arterioles within the granulation tissue. Our results provide important insights into the mechanism of action of biostimulating laser therapy on OM in vivo and pave a way for clinical experimentation with the use of high-power laser therapy.

  19. Laser therapy on points of acupuncture: Are there benefits in dentistry?

    Science.gov (United States)

    de Oliveira, Renata Ferreira; da Silva, Camila Vieira; Cersosimo, Maria Cecília Pereira; Borsatto, Maria Cristina; de Freitas, Patrícia Moreira

    2015-10-01

    Studies have shown the use of laser therapy at points of acupuncture as an alternative to metal needles. The scientific literature in the area of laser acupuncture is rather large; however, the actual mechanisms and effects have not yet been proven in detail. Therefore, the current manuscript reviews the existing literature regarding the effects of laser acupuncture in Dentistry, seeking treatment modalities in which this technique is used and which are able to generate positive clinical results. Thus, the literature survey was conducted in electronic databases--Medline/Pubmed, VHL and Science Direct--using the uniterms "alternative medicine", "low-power laser and acupuncture", "laser acupuncture and dentistry" and "laser therapy and acupuncture". Retrospective and prospective clinical studies were considered. According to the findings of the literature, laser therapy at points of acupuncture was effective for the treatment of various orofacial problems encountered in dentistry, but there are still many differences among the parameters used for irradiation and there is a lack of important information reported by the studies, such as the wavelength, dose, power density, irradiation time and frequency, points of acupuncture selected for irradiation and therapy outcomes. Although these results indicate the potential benefit of the use of laser therapy at points of acupuncture on Dentistry, further double-blinded, controlled clinical trials should be carried out in order to standardize protocols for clinical application.

  20. Development of the laser absorption radiation thermometry technique to measure thermal diffusivity in addition to temperature

    Science.gov (United States)

    Levick, Andrew; Lobato, Killian; Edwards, Gordon

    2003-01-01

    A comparative technique based on photothermal radiometry has been developed to measure thermal diffusivity of semi-infinite targets with arbitrary geometry. The technique exploits the principle that the frequency response of the temperature modulation induced by a periodic modulated heating source (in this case a laser spot) scales with thermal diffusivity. To demonstrate this technique, a photothermal radiometer has been developed, which detects modulated thermal radiance at a wavelength of 2 μm due to a small temperature modulation induced on the target surface by a modulated erbium fiber laser of power 1 W. Two frequency responses were measured for platinum and oxidized Inconel 600 targets (the frequency response is a scan of the amplitude of the modulated thermal radiance over laser modulation frequency). Scaling the two responses with respect to frequency gives a ratio of thermal diffusivities Dplatinum/DInconel of 4.45(33) which compares with a literature value of 4.46(50). The aim is to combine this technique with laser absorption radiation thermometry to produce multithermal property instrument for measuring "industrial" targets.

  1. Intra-oral laser welding: an in vitro evaluation of thermal increase.

    Science.gov (United States)

    Fornaini, C; Bertrand, C; Rocca, J P; Mahler, P; Bonanini, M; Vescovi, P; Merigo, E; Nammour, S

    2010-07-01

    The neodymium:yttrium-aluminium-garnet (Nd:YAG) laser is currently used in dental laboratories to weld metals on dental prostheses. Recently, the use of Nd:YAG has been suggested so that dentists themselves can repair broken fixed, removable and orthodontic prostheses by welding metals directly in the mouth. This work aimed to evaluate, through a four k-type thermocouple system on calf jaws, the thermal increase in the biological structures close to the metal parts during laser welding. We put two hemispherical metal plates onto mandibular molars and then laser welded them at three points with a four k-thermocouple system to determine the thermal rise in the pulp chamber, sulcus, root and bone. This procedure was carried out on 12 samples, and the results were processed. The highest values of thermal increase were found in the pulp chamber, 1.5 degrees C; sulcus, 0.7 degrees C; root, 0.3 degrees C; and bone, 0.3 degrees C. This study showed that thermal increases in pulp chamber, sulcus, root and bone were biologically compatible and that intra-oral laser welding, at the parameters used in this work, seems to be harmless to the biological structures close to the welding and thermally affected zones.

  2. Evaluation of thermal effects on the beam quality of disk laser with unstable resonator

    Science.gov (United States)

    Shayganmanesh, Mahdi; Beirami, Reza

    2017-01-01

    In this paper thermal effects of the disk active medium and associated effects on the beam quality of laser are investigated. Using Collins integral and iterative method, transverse mode of an unstable resonator including a Yb:YAG active medium in disk geometry is calculated. After that the beam quality of the laser is calculated based on the generalized beam characterization method. Thermal lensing of the disk is calculated based on the OPD (Optical Path Difference) concept. Five factors influencing the OPD including temperature gradient, disk thermal expansion, photo-elastic effect, electronic lens and disk deformation are considered in our calculations. The calculations show that the effect of disk deformation factor on the quality of laser beam in the resonator is strong. However the total effect of all the thermal factors on the internal beam quality is fewer. Also it is shown that thermal effects degrade the output power, beam profile and beam quality of the output laser beam severely. As well the magnitude of each of affecting factors is evaluated distinctly.

  3. Thermal Transient Measurement, Modeling, and Compensation of a Widely Tunable Laser for an Optically Switched Network

    Science.gov (United States)

    Mulvihill, Gavin; O'Dowd, Ronan

    2005-12-01

    The continuous growth of telecommunications traffic has placed huge demands on the traditional networks. Bottlenecks are particularly evident at the routers, where optical to electrical conversion must take place to read the routing information. Using optical-only routing, the traffic flow would be much faster, and more streamlined. A key component in this optical router is the tunable laser. When the laser is switched at high speeds, red-shifted thermal effects, due to the heating effects of the applied currents, cause a drift in the frequency, in the opposite direction to the blue-shifted carrier effects. The thermal effects have been quantified theoretically and experimentally here. The impact of the thermal effects, both on the frequency switching and on the frequency-shift keying (FSK), has been investigated. Methods of compensating for the thermal effects have been developed and verified by simulation and by experiment.

  4. Optimum Pulse Duration and Radiant Exposure for Vascular Laser Therapy of Dark port-wine Skin: A Theoretical Study

    Science.gov (United States)

    Tunnell, James W.; Wang, Lihong V.; Anvari, Bahman

    2003-03-01

    Laser therapy for cutaneous hypervascular malformations such as port-wine stain birthmarks is currently not feasible for dark-skinned individuals. We study the effects of pulse duration, radiant exposure, and cryogen spray cooling (CSC) on the thermal response of skin, using a Monte Carlo based optical-thermal model. Thermal injury to the epidermis decreases with increasing pulse duration during irradiation at a constant radiant exposure; however, maintaining vascular injury requires that the radiant exposure also increase. At short pulse durations, only a minimal increase in radiant exposure is necessary for a therapeutic effect to be achieved because thermal diffusion from the vessels is minimal. However, at longer pulse durations the radiant exposure must be greatly increased. There exists an optimum pulse duration at which minimal damage to the epidermis and significant injury within the targeted vasculature occur. For example, the model predicts optimum pulse durations of approximately 1.5, 6, and 20 ms for vessel diameters of 40, 80, and 120 μm, respectively. Optimization of laser pulse duration and radiant exposure in combination with CSC may offer a means to treat cutaneous lesions in dark-skinned individuals.

  5. Microstructure Analysis of Laser Remelting for Thermal Barrier Coatings on the Surface of Titanium Alloy

    Directory of Open Access Journals (Sweden)

    Lu Bin

    2016-01-01

    Full Text Available In this paper, the preparation and organization performance of thermal barrier coatings (TCBs on the surface of titanium were studied experimentally. Nanostructured 8 wt% yttria partially stabilized zirconia coatings were deposited by air plasma spraying. The microstructure of nanostructured and the conventional coating was studied after laser remelting. It has shown that formed a network of micro-cracks and pits after laser remelting on nanostructured coatings. With the decrease of the laser scanning speed, mesh distribution of micro cracks was gradually thinning on nanostructured coatings. Compared with conventional ceramic layers, the mesh cracks of nanostructured coating is dense and the crack width is small.

  6. Blinding Techniques in Randomized Controlled Trials of Laser Therapy: An Overview and Possible Solution

    Directory of Open Access Journals (Sweden)

    Ian Relf

    2008-01-01

    Full Text Available Low-level laser therapy has evidence accumulating about its effectiveness in a variety of medical conditions. We reviewed 51 double blind randomized controlled trials (RCTs of laser treatment. Analysis revealed 58% of trials showed benefit of laser over placebo. However, less than 5% of the trials had addressed beam disguise or allocation concealment in the laser machines used. Many of the trials used blinding methods that rely on staff cooperation and are therefore open to interference or bias. This indicates significant deficiencies in laser trial methodology. We report the development and preliminary testing of a novel laser machine that can blind both patient and operator to treatment allocation without staff participation. The new laser machine combines sealed preset and non-bypassable randomization codes, decoy lights and sound, and a conical perspex tip to overcome laser diode glow detection.

  7. Determining the effect of laser acupuncture in treating stutterers in comparison with speech therapy

    Directory of Open Access Journals (Sweden)

    Bijan Shafiei

    2015-01-01

    Full Text Available Background: Investigation of strategies and methods of therapy in stutterers regarding to its characteristics, length of treatment, and relapse of stuttering is very important. Acupuncture has been introduced as a therapeutic method for the treatment of stuttering. The aim of the present research was the identification of the results of intervention of laser acupuncture in comparison with speech therapy in stutterers. Materials and Methods: This clinical - trial and case control research was conducted on 20 stutterers and 20 non-stutterers. In the present study, speech therapy and laser acupuncture were used on 10 persons who had developmental stuttering from childhood. Results: The results were compared with the data of speech therapy and placebo laser in 10 control subjects. All of the subjects were followed up for 12 weeks after the intervention. The obtained data showed that accompanying of speech therapy with laser acupuncture resulted the increasing of maintenance and therapeutic effects of stuttering treatment and decreasing of relapsing. The speech rate and percent of stuttered words before and after the intervention in both groups (A and B were decreased. Following the results after 12 weeks showed that the results were stable in laser group more than the other group and there was a significant difference between the two groups. Conclusion: The results of the present study showed that using of laser acupuncture therapy accompanying by speech therapy has many effects on the treatment of stuttering and prevents the relapsing of stuttering that is very common.

  8. Development and thermal management of 10 kW CW, direct diode laser source

    Science.gov (United States)

    Zhu, Hongbo; Hao, Mingming; Zhang, Jianwei; Ji, Wenyu; Lin, Xingchen; Zhang, Jinsheng; Ning, Yongqiang

    2016-01-01

    We report on the development of direct diode laser source with high-power and high reliability. The laser source was realized by the polarization and wavelength combination of four diode laser stacks. When at the operating current of 122 A, the source was capable of producing 10,120 W output while maintaining 46% electro-optical conversion efficiency. The maximum temperature on the lens was decreased from 442.2 K to 320 K by utilizing an efficient thermal dissipation structure, and the corresponding maximum von Mises stress was reduced from 75.4 MPa to 14 MPa. In addition, a reliability test demonstrated that our laser source was reliable and potential in the applications of laser cladding and heat treatment.

  9. COUPLED ELECTRICAL-THERMAL MECHANICAL ANALYSIS FOR ELECTRICAL/LASER HEATING ASSISTED BLANKING

    Institute of Scientific and Technical Information of China (English)

    PENG Xianghe; QIN Yi

    2006-01-01

    A coupled electrical-thermal-mechanical analysis is conducted for electrical/laser heating assisted blanking. Two novel localized-heating methods, electrical heating and laser-heating, recently proposed for small-part blanking, are investigated with FE simulations. Results show that electrical heating would result in an advantageous distribution of temperature in a 316 stainless steel work-material. A desired temperature distribution may also be achievable for a copper work-material,if laser beam is used. Both electrical heating and laser-heating enable to reduce the blanking force and increase the aspect ratio achievable by blanking. The simulation also demonstrates that both electrical heating and laser-heating can result in desired temperature-distributions at sufficiently high heating-rates, ease of implementation and application. Comparatively, electrical heating could generate more favorable temperature distribution for small-part blanking.

  10. Thermal laser-assisted angioplasty of renal artery stenosis for renovascular hypertension.

    Science.gov (United States)

    Tani, M; Mizuno, K; Midorikawa, H; Igari, T; Egawa, M; Niimura, S; Fukuchi, S; Hoshino, S

    1993-01-01

    Percutaneous transluminal laser-assisted angioplasty of a renal artery stenosis was performed in a 16-year-old woman with renovascular hypertension. The stenotic portion of the renal artery was predilated by delivering Nd-YAG laser energy to the terminal tip of a laser catheter. Although the luminal diameter did not increase sufficiently with laser angioplasty alone, it allowed passage of the balloon catheter and subsequent successful balloon angioplasty. Immediately after dilatation, the patient's blood pressure fell to normal, and plasma renin activity decreased. There were no serious complications. Thermal laser angioplasty seems to be an effective adjunct technique for the treatment of severe renal artery stenosis which does not allow initial passage of a balloon catheter.

  11. Suppression of thermal frequency noise in erbium-doped fiber random lasers.

    Science.gov (United States)

    Saxena, Bhavaye; Bao, Xiaoyi; Chen, Liang

    2014-02-15

    Frequency and intensity noise are characterized for erbium-doped fiber (EDF) random lasers based on Rayleigh distributed feedback mechanism. We propose a theoretical model for the frequency noise of such random lasers using the property of random phase modulations from multiple scattering points in ultralong fibers. We find that the Rayleigh feedback suppresses the noise at higher frequencies by introducing a Lorentzian envelope over the thermal frequency noise of a long fiber cavity. The theoretical model and measured frequency noise agree quantitatively with two fitting parameters. The random laser exhibits a noise level of 6  Hz²/Hz at 2 kHz, which is lower than what is found in conventional narrow-linewidth EDF fiber lasers and nonplanar ring laser oscillators (NPROs) by a factor of 166 and 2, respectively. The frequency noise has a minimum value for an optimum length of the Rayleigh scattering fiber.

  12. Problems for determining the thermal conductivity of TBCs by laser-flash method

    OpenAIRE

    2008-01-01

    Purpose: The purpose of this paper was to investigate the parameters which effect the results of determining the thermal conductivity of thermal barrier coatings (TBCs) by laser-flash method.Design/methodology/approach: The air plasma-spray (APS) technique was used to deposition of two- and three-layered samples. Two-layered samples were composed of metal substrate (321 stainless steel), and ceramic top coat (8YSZ). Three-layered samples were composed of metal substrate (321 ...

  13. Digital wavelength switching by thermal and carrier injection effects in V-coupled cavity semiconductor laser

    Institute of Scientific and Technical Information of China (English)

    Jialiang Jin; Lei Wang; Jianjun He

    2012-01-01

    Consecutive wavelength switching characteristics of a simple,compact,and digitally wavelength-switchable laser based on V-coupled cavities are reported.Wavelength switching through thermal and carrier injection effects is examined.Without using band gap engineering for the tuning section,26- and 9-channel wavelength switching schemes are achieved via thermal and carrier injection effects,respectively.The performances of these two tuning schemes are then compared.

  14. Thermal conductivity and electron-phonon relaxation in a metal heated by a subpicosecond laser pulse

    Science.gov (United States)

    Petrov, Yu. V.; Anisimov, S. I.

    2006-06-01

    This paper discusses the initial stages of the interaction of subpicosecond laser pulses with metallic targets: the absorption of light, energy transport by electronic thermal conductivity, and electron-phonon relaxation. It is shown that, with moderate surface energy density, hydrodynamic motion begins after the electronic and lattice temperatures equalize. A connection is established between the energy exchange rate between the electrons and the lattice and the electronic thermal conductivity (an analog of the Wiedemann-Franz law).

  15. Pulsed-laser Pumped Photothermal Deflection Spectroscopy for Liquid Thermal Diffusivity Measurement

    Institute of Scientific and Technical Information of China (English)

    XIAO Liantuan; LI Changyong; ZHANG Linjie; ZHAO Yanting; JIA Suotang; ZHOU Guosheng

    2000-01-01

    The pulsed-laser pumped photothermal deflection spectroscopy (PPDS) is applied to measure liquid thermal diffusivity in a modified collinear configuration. Here the pulsed beam is regarded as in the form of a Dirac delta function. The experiment setup used is described. Measurement result for the thermal diffusivity of a liquid sample(magnta/ethanol saturated solution) is reported. The measurement error is less than 3%.

  16. Application and possible mechanisms of combining LLLT (low level laser therapy), infrared hyperthermia and ionizing radiation in the treatment of cancer

    Science.gov (United States)

    Abraham, Edward H.; Woo, Van H.; Harlin-Jones, Cheryl; Heselich, Anja; Frohns, Florian

    2014-02-01

    Benefit of concomitant infrared hyperthermia and low level laser therapy and ionizing radiation is evaluated in this study. The purpose/objectives: presentation with locally advanced bulky superficial tumors is clinically challenging. To enhance the efficacy of chemotherapy and IMRT (intensity-modulated radiation therapy) and/or electron beam therapy we have developed an inexpensive and clinically effective infrared hyperthermia approach that combines black-body infrared radiation with halogen spectrum radiation and discrete wave length infrared clinical lasers LLLT. The goal is to produce a composite spectrum extending from the far infrared to near infrared and portions of the visible spectrum with discrete penetrating wavelengths generated by the clinical infrared lasers with frequencies of 810 nm and/or 830 nm. The composite spectrum from these sources is applied before and after radiation therapy. We monitor the surface and in some cases deeper temperatures with thermal probes, but use an array of surface probes as the limiting safe thermal constraint in patient treatment while at the same time maximizing infrared entry to deeper tissue layers. Fever-grade infrared hyperthermia is produced in the first centimeters while non-thermal infrared effects act at deeper tissue layers. The combination of these effects with ionizing radiation leads to improved tumor control in many cancers.

  17. Influence of the contaminant size on the thermal damage of optical mirrors used in high energy laser system

    Science.gov (United States)

    Han, Kai; Song, Rui; Xu, Xiaojun; Liu, Zejin

    2016-09-01

    The laser induced damage is a troublesome issue in the application of optical mirrors, which is related to the robustness of the whole laser system. There are two types of mechanisms about the damage of optical mirrors: thermal effect and field effect, which are responsible for the high energy continuous wave (cw) laser induced damage and the high power pulsed laser induced damage, respectively. Under the irradiation of high energy laser, the contaminant on the mirror surface absorbs the laser energy and converts the laser energy to heat. With the heat accumulating, the optical mirror is likely to fuse and even be totally destroyed. The temperature of the contaminant was measured when it was irradiated by a cw high energy laser with power intensity 3.3kW/cm2. It is found that the contaminant achieves thermal equilibrium in a few seconds and then the temperature stays at 1700K. A physical model was established to describe the process of the thermal equilibrium. The influence of the contaminant size on the thermal damage of the optical mirror was studied theoretically. The results show that the contaminant size plays an important role in the thermal damage of the optical mirror. Only when the contaminant size is smaller than a critical size ( 10μm), the contaminant may reach thermal equilibrium and the optical mirror works well in the high energy laser system. If the contaminant size is quite large (mirror will damage under the irradiation of high energy laser.

  18. Laser Irradiation Blood Therapy and Laser Irradiation Magnetized Blood Therapy%激光辐照血液疗法和激光磁化血液疗法

    Institute of Scientific and Technical Information of China (English)

    周孝南; 耿照连

    2001-01-01

    The development and types of Light Irradiation Blood T herapy and the invention of Laser Irradiation Magnetized Blood Therapy are brief ly reviewed.The biological effects of light,laser beam and magnetic field on blo od and its possible mechanism of Laser Irraadiation Magnetized Blood Therapy are discussed in the paper.Various Light Irradiation Blood Therapies are compared.%简要回顾光辐照血液疗法的发展和类型以及激光磁化血液疗法的兴起.概述光、激光和磁场对血液的生物效应,初步探讨激光磁化血液疗法可能的作用机制.最后进行了多种光辐照血液疗法的初步对比.

  19. Versatility of diode lasers in low-level laser therapy for the management of recurrent aphthous stomatitis

    OpenAIRE

    2015-01-01

    Recurrent aphthous stomatitis (RAS) is a painful condition, often leading to impairment of the basic functions such as mastication, speech, and brushing. Several treatment modalities have been advocated in the past, but none hasve been proven efficacious. A novel treatment modality in the form of low-level laser therapy (LLLT) has evolved in recent years. LLLT also known as "cold laser" works on the principle of biostimulation. This biomodulatory effect plays a pivotal role in accelerating th...

  20. Thermal conductivity enhancement of laser induced graphene foam upon P3HT infiltration

    Science.gov (United States)

    Smith, M. K.; Luong, D. X.; Bougher, T. L.; Kalaitzidou, K.; Tour, J. M.; Cola, B. A.

    2016-12-01

    Significant research has been dedicated to the exploration of high thermal conductivity polymer composite materials with conductive filler particles for use in heat transfer applications. However, poor particle dispersibility and interfacial phonon scattering have limited the effective composite thermal conductivity. Three-dimensional foams with high ligament thermal conductivity offer a potential solution to the two aforementioned problems but are traditionally fabricated through expensive and/or complex manufacturing methods. Here, laser induced graphene foams, fabricated through a simple and cost effective laser ablation method, are infiltrated with poly(3-hexylthiophene) in a step-wise fashion to demonstrate the impact of polymer on the thermal conductivity of the composite system. Surprisingly, the addition of polymer results in a drastic (250%) improvement in material thermal conductivity, enhancing the graphene foam's thermal conductivity from 0.68 W/m-K to 1.72 W/m-K for the fully infiltrated composite material. Graphene foam density measurements and theoretical models are utilized to estimate the effective ribbon thermal conductivity as a function of polymer filling. Here, it is proposed that the polymer solution acts as a binding material, which draws graphene ligaments together through elastocapillary coalescence and bonds these ligaments upon drying, resulting in greatly reduced contact resistance within the foam and an effective thermal conductivity improvement greater than what would be expected from the addition of polymer alone.

  1. Thermal proton transfer reactions in ultraviolet matrix-assisted laser desorption/ionization.

    Science.gov (United States)

    Chu, Kuan Yu; Lee, Sheng; Tsai, Ming-Tsang; Lu, I-Chung; Dyakov, Yuri A; Lai, Yin Hung; Lee, Yuan-Tseh; Ni, Chi-Kung

    2014-03-01

    One of the reasons that thermally induced reactions are not considered a crucial mechanism in ultraviolet matrix-assisted laser desorption ionization (UV-MALDI) is the low ion-to-neutral ratios. Large ion-to-neutral ratios (10(-4)) have been used to justify the unimportance of thermally induced reactions in UV-MALDI. Recent experimental measurements have shown that the upper limit of the total ion-to-neutral ratio is approximately 10(-7) at a high laser fluence and less than 10(-7) at a low laser fluence. Therefore, reexamining the possible contributions of thermally induced reactions in MALDI may be worthwhile. In this study, the concept of polar fluid was employed to explain the generation of primary ions in MALDI. A simple model, namely thermal proton transfer, was used to estimate the ion-to-neutral ratios in MALDI. We demonstrated that the theoretical calculations of ion-to-neutral ratios exhibit the same trend and similar orders of magnitude compared with those of experimental measurements. Although thermal proton transfer may not generate all of the ions observed in MALDI, the calculations demonstrated that thermally induced reactions play a crucial role in UV-MALDI.

  2. Effect of quantum correction on nonlinear thermal wave of electrons driven by laser heating

    Science.gov (United States)

    Nafari, F.; Ghoranneviss, M.

    2016-08-01

    In thermal interaction of laser pulse with a deuterium-tritium (DT) plane, the thermal waves of electrons are generated instantly. Since the thermal conductivity of electron is a nonlinear function of temperature, a nonlinear heat conduction equation is used to investigate the propagation of waves in solid DT. This paper presents a self-similar analytic solution for the nonlinear heat conduction equation in a planar geometry. The thickness of the target material is finite in numerical computation, and it is assumed that the laser energy is deposited at a finite initial thickness at the initial time which results in a finite temperature for electrons at initial time. Since the required temperature range for solid DT ignition is higher than the critical temperature which equals 35.9 eV, the effects of quantum correction in thermal conductivity should be considered. This letter investigates the effects of quantum correction on characteristic features of nonlinear thermal wave, including temperature, penetration depth, velocity, heat flux, and heating and cooling domains. Although this effect increases electron temperature and thermal flux, penetration depth and propagation velocity are smaller. This effect is also applied to re-evaluate the side-on laser ignition of uncompressed DT.

  3. Imposed Thermal Fatigue and Post-Thermal-Cycle Wear Resistance of Biomimetic Gray Cast Iron by Laser Treatment

    Science.gov (United States)

    Sui, Qi; Zhou, Hong; Zhang, Deping; Chen, Zhikai; Zhang, Peng

    2017-08-01

    The present study aims to create coupling biomimetic units on gray cast iron substrate by laser surface treatment (LST). LSTs for single-step (LST1) and two-step (LST2) processes, were carried out on gray cast iron in different media (air and water). Their effects on microstructure, thermal fatigue, and post-thermal-cycle wear (PTW) resistance on the specimens were studied. The tests were carried out to examine the influence of crack-resistance behavior as well as the biomimetic surface on its post-thermal-cycle wear behavior and different units, with different laser treatments for comparison. Results showed that LST2 enhanced the PTW behaviors of gray cast iron, which then led to an increase in its crack resistance. Among the treated cast irons, the one treated by LST2 in air showed the lowest residual stress, due to the positive effect of the lower steepness of the thermal gradient. Moreover, the same specimen showed the best PTW performance, due to its superior crack resistance and higher hardness as a result of it.

  4. Variable depth thermal lesions in rabbit corneas using a tunable thulium fiber laser

    Science.gov (United States)

    Fried, Nathaniel M.; Noguera, Guillermo; Castro-Combs, Juan; Behrens, Ashley

    2007-02-01

    Laser-induced thermal changes in the cornea have been used clinically for refractive surgery. This study describes the creation of variable depth thermal lesions in the cornea using a tunable Thulium fiber laser. Thermal lesions were created in fresh rabbit corneas, ex vivo, at three different wavelengths (1873 nm, 1890 nm, and 1904 nm) (n=6 corneas each). All other laser parameters were kept fixed with power of 5.5 W, 25-ms exposure time, and 650-μm diameter spot, yielding a single pulse exposure of 138 mJ, and a fluence of 42 J/cm2. Optical coherence tomography (OCT) and histology were used to measure pre- and post-operative corneal thickness and lesion dimensions. OCT measurements of pre and post-operative corneal thickness and lesion depth (in microns) were: (1873 nm: 450+/-30, 801+/-95, 655+/-51), (1890 nm: 460+/-27, 618+/-70, 332+/-56), (1904 nm: 448+20, 550+/-42, 245+36), respectively. By comparison, histologic measurements were: (1873 nm: 470+25, 828+21, 540+/-31), (1890 nm: 457+/-13, 625+/-17, 350+/-43), (1904 nm: 465+/-40, 627+/-35, 239+/-23), respectively. OCT lesion depth measured 82%, 54%, and 45% of corneal thickness, compared to histologic analysis of 65%, 56%, and 38%. This is the first preliminary test of a compact and tunable Thulium fiber laser for creating variable depth thermal lesions in the cornea. The Thulium fiber laser may have potential use as a replacement for the Ho:YAG and diode lasers for thermal keratoplasty.

  5. Measuring cutaneous thermal nociception in group-housed pigs using laser technique - effects of laser power output

    DEFF Research Database (Denmark)

    Herskin, Mette S.; Ladevig, Jan; Arendt-Nielsen, Lars

    2009-01-01

    of the metatarsus were examined using 15 gilts kept in one group and tested in individual feeding stalls after feeding. Increasing the power output led to gradually decreasing latency to respond (P ... are available, especially methodology which is applicable for pigs kept in group-housing without disturbing the daily routines of the animals. To validate a laser-based method to measure thermal nociception in group-housed pigs, we performed two experiments observing the behavioural responses toward cutaneous...... nociceptive stimulation from a computer-controlled CO2-laser beam applied to either the caudal part of the metatarsus on the hind legs or the shoulder region of gilts. In Exp. 1, effects of laser power output (0, 0.5, 1, 1.5 and 2 W) on nociceptive responses toward stimulation on the caudal aspects...

  6. Laser therapy in plastic surgery: decolorization in port wine stains

    Science.gov (United States)

    Peszynski-Drews, Cezary; Wolf, Leszek

    1996-03-01

    For the first time laserotherapy is described as a method of port wine stain decolorization in plastic surgery. The authors present their 20-year experience in the treatment of port wine stains with the argon laser and dye laser.

  7. Measurement of thermal lensing in end-pumped Yb-doped yttrium vanadate crystal and sesquioxide laser ceramics

    Science.gov (United States)

    Pestryakov, E. V.; Petrov, V. V.; Trunov, V. I.; Kirpichnikov, A. V.; Merzliakov, M. A.; Laptev, A. V.; Polyakov, K. V.

    2011-02-01

    The results of theoretical and experimental study of thermal lensing in diode-pumped Yb:YVO4 laser crystal, Yb:Y2O3 and Yb:Sc2O3 laser ceramics are presented. Shown, that influence of thermo-lensing effect is necessary to consider for creation of effective high-intensity femtosecond Yb-doped laser systems.

  8. Monolithic thermally bonded Er3+, Yb3+:glass/Co2+:MgAl2O4 microchip lasers

    Science.gov (United States)

    Mlynczak, Jaroslaw; Belghachem, Nabil

    2015-12-01

    The highest ever reported 10 kW peak power in monolithic thermally bonded Er3+, Yb3+:glass/Co2+:MgAl2O4 microchip laser was achieved. To show the superiority of monolithic microchip lasers over those with external mirrors the laser generation characteristics of the same samples in both cases were compared.

  9. Thermally robust semiconductor optical amplifiers and laser diodes

    Science.gov (United States)

    Dijaili, Sol P.; Patterson, Frank G.; Walker, Jeffrey D.; Deri, Robert J.; Petersen, Holly; Goward, William

    2002-01-01

    A highly heat conductive layer is combined with or placed in the vicinity of the optical waveguide region of active semiconductor components. The thermally conductive layer enhances the conduction of heat away from the active region, which is where the heat is generated in active semiconductor components. This layer is placed so close to the optical region that it must also function as a waveguide and causes the active region to be nearly the same temperature as the ambient or heat sink. However, the semiconductor material itself should be as temperature insensitive as possible and therefore the invention combines a highly thermally conductive dielectric layer with improved semiconductor materials to achieve an overall package that offers improved thermal performance. The highly thermally conductive layer serves two basic functions. First, it provides a lower index material than the semiconductor device so that certain kinds of optical waveguides may be formed, e.g., a ridge waveguide. The second and most important function, as it relates to this invention, is that it provides a significantly higher thermal conductivity than the semiconductor material, which is the principal material in the fabrication of various optoelectronic devices.

  10. Intensified photodynamic therapy of actinic keratoses with fractional CO2 laser

    DEFF Research Database (Denmark)

    Togsverd-Bo, K; Haak, C S; Thaysen-Petersen, D

    2012-01-01

    Photodynamic therapy (PDT) with methyl aminolaevulinate (MAL) is effective for thin actinic keratoses (AKs) in field-cancerized skin. Ablative fractional laser resurfacing (AFXL) creates vertical channels that facilitate MAL uptake and may improve PDT efficacy.......Photodynamic therapy (PDT) with methyl aminolaevulinate (MAL) is effective for thin actinic keratoses (AKs) in field-cancerized skin. Ablative fractional laser resurfacing (AFXL) creates vertical channels that facilitate MAL uptake and may improve PDT efficacy....

  11. Feasibility of abdomino-pelvic T1-weighted real-time thermal mapping of laser ablation.

    Science.gov (United States)

    Dick, Elizabeth A; Wragg, Paul; Joarder, Rita; de Jode, Michael; Lamb, Gabrielle; Gould, Stuart; Gedroyc, Wladyslaw M W

    2003-02-01

    To prove the hypothesis that T1-weighted (T1W) thermal mapping is reliable and achievable in magnetic resonance (MR)-guided laser tumor ablation. Near real-time gray and color-scale T1W thermal maps in 111 MR-guided laser thermal ablations (LTA) of liver, kidney, and uterine tumors were studied. After laser fiber placement, near real-time gray and color-scale thermal maps were produced. Previous work showed T1 signal is inversely proportional to temperature below 55 degrees C (the point of irreversible necrosis). Thermal mapping was successful in 84% of uterine, 74% of hepatic, and 20% of renal ablations. For hepatic and uterine tumors, size and conspicuity of thermal lesions were significantly greater on subtracted colorized images rather than gray-scale raw image mapping (P = 0.001, paired Student's t-test). Patient movement (N = 24), fiber charring N = 2), magnetic field distortion, and reconstruction errors (N = 2) caused mapping failure. For both renal and hepatic tumors, comparison of near real-time T1W colorized thermal map and follow up gadolinium-enhanced MR imaging revealed moderate correlation (Pearson correlation coefficient of 0.55 and 0.5, respectively). In hepatic, renal, and uterine thermal maps, the color scale produced significantly greater sized lesions with significantly greater conspicuity than the gray scale. T1W thermal mapping was reliable and successfully achieved in 73.7% of procedures, and predicted the ablated area of the tumor moderately well. Copyright 2003 Wiley-Liss, Inc.

  12. Laser therapy and sclerotherapy in the treatment of oral and maxillofacial hemangioma and vascular malformations

    Science.gov (United States)

    Crişan, Bogdan; BǎciuÅ£, Mihaela; BǎciuÅ£, Grigore; Crişan, Liana; Bran, Simion; Rotar, Horatiu; Moldovan, Iuliu; Vǎcǎraş, Sergiu; Mitre, Ileana; Barbur, Ioan; Magdaş, Andreea; Dinu, Cristian

    2016-03-01

    Hemangioma and vascular malformations in the field of oral and maxillofacial surgery is a pathology more often found in recent years in patients. The aim of this study was to evaluate the efficacy of the laser photocoagulation performed with a diode laser (Ga-Al-As) 980 nm wavelength in the treatment of vascular lesions which are located on the oral and maxillofacial areas, using color Doppler ultrasonography for evaluation of the results. We also made a comparison between laser therapy and sclerotherapy in order to establish treatment protocols and recommendations associated with this pathology. We conducted a controlled study on a group of 92 patients (38 male and 54 female patients, with an average age of 36 years) having low flow hemangioma and vascular malformations. Patients in this trial received one of the methods of treatment for vascular lesions such as hemangioma and vascular malformations: laser therapy or sclerotherapy. After laser therapy we have achieved a reduction in size of hemangioma and vascular malformations treated with such a procedure, and the aesthetic results were favorable. No reperfusion or recanalization of laser treated vascular lesions was observed after an average follow-up of 6 to 12 months. In case of sclerotherapy a reduction in the size of vascular lesions was also obtained. The 980 nm diode laser has been proved to be an effective tool in the treatment of hemangioma and vascular malformations in oral and maxillofacial area. Laser therapy in the treatment of vascular lesions was more effective than the sclerotherapy procedure.

  13. The Effect of Low-level Laser Therapy on Trigeminal Neuralgia: A Review of Literature

    Directory of Open Access Journals (Sweden)

    Farnaz Falaki

    2014-03-01

    Full Text Available The effect of low intensity laser radiation in the treatment of acute and chronic pain is now established in many studies. Trigeminal neuralgia is a pain passes through nerve’s branches and its trigger is located in skin or mucosa that could lead to pain with a trigger stimulus. The pain involved branches of trigeminal nerve that sometimes has patients to seek the treatment for several years. Nowadays different treatments are used for relief of pain that most of them cause tolerance and various side effects. This paper reviews and summarizes scientific papers available in English literature published in PubMed, Scopus, Science Direct, Inter science, and Iran Medex from 1986 until July 2011 about the effect of these types of lasers on trigeminal neuralgia which is one of the most painful afflictions known. In different studies, the effect of laser therapy has been compared with placebo irradiation or medicinal and surgical treatment modalities. Low-level laser therapy (LLLT is a treatment strategy which uses a single wavelength light source. Laser radiation and monochromatic light may alter cell and tissue function. However, in most studies laser therapy was associated with significant reduction in the intensity and frequency of pain compared with other treatment strategies, a few studies revealed that between laser and placebo group there was not any significant difference according to the analgesic effect. Low-level laser therapy could be considered in treatment of trigeminal neuralgia without any side effects.

  14. The effect of a pulsed Nd:YAG laser in non-surgical periodontal therapy

    NARCIS (Netherlands)

    Slot, D.E.; Kranendonk, A.A.; Paraskevas, S.; van der Weijden, F.

    2009-01-01

    Background: Laser treatment may serve as an alternative or adjunctive treatment to conventional mechanical therapy in periodontics. The neodymium-doped:yttrium, aluminum, and garnet (Nd:YAG) laser has been used in periodontics. Systematic reviews aid in clinical decision-making. The aim of this stud

  15. Theoretical analysis of thermal effects in fiber laser from the moment when pump is turned on to steady-state

    Institute of Scientific and Technical Information of China (English)

    Zilun Chen; Jing Hou; Zongfu Jiang

    2007-01-01

    A theoretical analysis of the pump-induced temperature change and associated thermal phase shift occurring in a fiber laser is presented. The temperature rise and thermal phase shift from the moment when pump is turned on to steady-state in fiber lasers, such as Yb-doped fiber laser, are numerical calculated.With the same parameters, the numerical solution is in good agreement with the finite-element (ANSYS software) simulation.

  16. Development of a thermal fatigue test method for thermal barrier coatings by laser excitation using a laser thermal shock facility; Entwicklung eines Pruefverfahrens zur laserinduzierten thermischen Ermuedung thermischer Schutzschichten mittels einer Laser-Thermoschockpruefeinrichtung

    Energy Technology Data Exchange (ETDEWEB)

    Nies, Daniel

    2012-07-13

    The finite nature of fossil fuel supply and the growing environmental awareness become increasingly stronger motivations for the development of efficient gas turbines and jet engines for power generation or as engines for land-, sea- and water-based vehicles. One concept developed for this purpose are thermal barrier coatings, where the thermal load of components is reduced by applying a ceramic coating onto the components. In this work the possibility to use a laser thermal shock facility for thermo-cyclic testing of thermal barrier coatings is examined. A focused laser beam is used for heating the sample and a homogeneous temperature distribution on the sample surface is achieved by the used trajectory and radial adjusted laser power. The required improvements of the existing testing facility are explained, including the development of a new sample holder and of the testing and evaluation routines for the experiments. For the assessment of the initiation and evolution of damages, acoustic emission and thermographic methods are used. The possibilities and limits of these methods are assessed during the experiments. The work also includes an extensive temperature dependent characterisation of the ceramic material used for the thermal barrier coating. In this part, the measurement of the Young's modulus by a dynamic method is to be highlighted, as this is a rarely used technique. The characterisations show the expected values, except for a lower porosity as expected by the manufacturer and no significant phase changes during isothermal heat treatments. To reach sample surface temperatures above 1000 C, it is necessary to increase the absorption by an additional coating of magnetite. The temperature distribution on the surface is measured by an infrared camera, which is calibrated for this purpose. With the incorporated active air cooling of the sample backside, the temperature gradient can be controlled, but still leaves room for improvements. Already without

  17. Importance of layer thermal conductivity on the sharpness of patterns produced by laser interference

    Energy Technology Data Exchange (ETDEWEB)

    Peláez, R.J., E-mail: rpelaez@io.cfmac.csic.es [Laser Processing Group, Instituto de Optica, CSIC, Serrano 121, 28006 Madrid (Spain); Afonso, C.N. [Laser Processing Group, Instituto de Optica, CSIC, Serrano 121, 28006 Madrid (Spain); Škereň, M. [Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Brehova 7, 115 19 Prague 1 (Czech Republic); Bulíř, J. [Institute of Physics, ASCR, v.v.i., Na Slovance 2, Prague (Czech Republic)

    2016-06-30

    Highlights: • Temperature profile matches laser intensity profile in poor thermally conducting layers. • Patterns produced in poor thermally conducting layers have sharp interfaces. • Lateral heat flow smears the temperature profile in thermally conducting layers. • Both liquid and solid state dewetting occurs upon patterning thermally conducting layers. • The thermal conductivity of layers limits the minimum period achievable. - Abstract: In this work, we compare patterns produced in Ag layers having similar thickness in the range 8.3–10.8 nm but having different initial nanostructure, i.e. behaving either as discontinuous or continuous layers and thus having very different thermal conductivities. The patterns are produced by exposing a phase mask to an excimer laser operating at 193 nm and using a projection optics that leads to similar fringed patterns with periods in the range 6.3–6.7 μm. The layer breaks up into isolated NPs due to laser induced melting at the regions around the intensity maxima sites. The resulting fringes have sharp interfaces in the case of discontinuous layers while a variety of regions across the pattern with no sharp interfaces are produced in the case of continuous layers. The results show that while the temperature distribution across the pattern matches almost perfectly the laser beam intensity profile for the former case, it becomes smeared due to lateral heat flow for the latter case. These results provide evidences for significant heating at the intensity minima sites that lead to solid-state dewetting and will eventually limit the minimum period achievable in the case of continuous metal layers or thermally conducting layers.

  18. Reduction of thermal fluctuations in a cryogenic laser interferometric gravitational wave detector

    CERN Document Server

    Uchiyama, Takashi; Telada, Souichi; Yamamoto, Kazuhiro; Ohashi, Masatake; Agatsuma, Kazuhiro; Arai, Koji; Fujimoto, Masa-Katsu; Haruyama, Tomiyoshi; Kawamura, Seiji; Miyakawa, Osamu; Ohishi, Naoko; Saito, Takanori; Shintomi, Takakazu; Suzuki, Toshikazu; Takahashi, Ryutaro; Tatsumi, Daisuke

    2012-01-01

    The thermal fluctuation of mirror surfaces is the fundamental limitation for interferometric gravitational wave (GW) detectors. Here, we experimentally demonstrate for the first time a reduction in a mirror's thermal fluctuation in a GW detector with sapphire mirrors from the Cryogenic Laser Interferometer Observatory at 17\\,K and 18\\,K. The detector sensitivity, which was limited by the mirror's thermal fluctuation at room temperature, was improved in the frequency range of 90\\,Hz to 240\\,Hz by cooling the mirrors. The improved sensitivity reached a maximum of $2.2 \\times 10^{-19}\\,\\textrm{m}/\\sqrt{\\textrm{Hz}}$ at 165\\,Hz.

  19. Low-level laser therapy and Calendula officinalis in repairing diabetic foot ulcers

    Directory of Open Access Journals (Sweden)

    Ana Flávia Machado de Carvalho

    Full Text Available Abstract OBJECTIVE To evaluate the effects of low-level laser therapy isolated and associated with Calendula officinalis oil in treating diabetic foot ulcers. METHOD An experimental, randomized, controlled, prospective, interventional clinical case study using a quantitative approach. The sample consisted of 32 diabetic patients of both genders. Participants were randomly divided into four groups. Doppler Ultrasound evaluation of the Ankle-Brachial Index, brief pain inventory and analog pain scale were performed at baseline and after 30 days. RESULTS Reduced pain was observed in the Low-level laser therapy and Low-level laser therapy associated with Essential Fatty Acids groups (p<0.01. Regarding the Ankle-Brachial Index and Doppler Ultrasound, all groups remained stable. By analyzing lesion area reduction, Low-level laser therapy associated with Essential fatty acids group showed a significance of p=0.0032, and the Low-level laser therapy group showed p=0.0428. CONCLUSION Low-level laser therapy, performed alone or associated with the Calendula officinalis oil was effective in relieving pain and accelerating the tissue repair process of diabetic foot.

  20. Laser Assisted Non-surgical Periodontal Therapy: A Double Blind, Randomized Clinical Trial

    Science.gov (United States)

    Everett, Joseph D.; Rossmann, Jeffrey A.; Kerns, David G.; Al-Hashimi, Ibtisam

    2017-01-01

    The objective of this study was to examine potential benefits of using laser therapy for secular decontamination in conjunction with scaling and root planing in the treatment of chronic periodontitis. The study was performed on 173 teeth in 14 patients in a split-mouth design, one side received scaling and root planing followed by laser therapy using a carbon dioxide (CO2) laser with an ablative handpiece (test group); the contralateral side received scaling and root planing without laser (control group). Clinical and laboratory parameters were evaluated prior to treatment and at 3 and 6 months following therapy; clinical measurements were performed by two blinded examiners. The clinical parameters included measurement of gingival recession (REC), bleeding on probing (BOP), clinical attachment level (CAL), pocket depth (PD), furcation involvement (FUR), and tooth mobility (MOB). Laboratory testing to determine the levels of periodontal pathogens was performed using PCR techniques. The results of the study revealed statistically significant differences in clinical and laboratory parameters at 3 and 6 months after therapy for both test and control groups, but no significant difference was observed between the two groups. However, sites receiving laser therapy tended to show a greater decrease in probing depths, gain in clinical attachment level, and reduced bacterial levels. In conclusion, the overall results of the study suggest a potential benefit of using laser therapy in conjunction with scaling and root planing for the treatment of chronic periodontitis. PMID:28357001

  1. Solutions of the modification heating conduction equations of a kind of laser thermal effect

    Institute of Scientific and Technical Information of China (English)

    Lingyun Zhou(周凌云); Canbang Zhang(张灿邦); Yiying Zhou; Guangmin Wu(吴光敏)

    2003-01-01

    This paper has solved the Chester modified heat conduction equation of the different relaxation time τ value under different temperature conditions, different boundary conditions and the different initial conditions by different means of methods. These solutions can help to obtain temperature field of laser thermal effects.

  2. [Thermographic assessment of thermal effects of Er:YAG laser in periodontal surgery].

    Science.gov (United States)

    Zmuda, Stanisław; Ignatowicz, Elzbieta; Stankiewicz, Justyna; Marczyńiska-Stolarek, Magdalena; Dabrowski, Mirosław

    2006-02-01

    An assessment of thermal effect of Er:YAG laser (KEYII, KaVo) on oral soft tissues in select procedures. Experimental researches were carried out on Wistar rats. To measure the temperature changes the thermal imaging camera (ThermaCAM SC3000, FLIR Systems) was used. There has been a significant increase of temperature observed on the end of optical fibre: the mean temperature ranged from 270 to 360 degrees C (at laser energy of 100 mJ and repetition rate of 25 Hz) and from 230 to 290 degrees C (300 mJ, 15 Hz). On the surface of oral mucosa thermal changes at the time of laser frenulectomy was analysed along the line of incision. The temperature above 50 degrees C was recorded on the length of 2 mm (at 100 mJ) and 3 mm (at 300 mJ). The temperature maintained on this level for about 0.4 s. On the surface of tongue during lingual mucosa excision the temperature above 40 degrees C was observed on the length of 1.6 mm (80 mJ, 2 Hz) or 2.5 mm (160 mJ, 2 Hz). The rate of cooling for both cases was lower than 0.5 s. To prevent undesirable thermal side effects from an Er:YAG laser optical fibre should be moved very fluently in non-contact mode.

  3. Incision properties and thermal effects of CO2 lasers in soft tissue

    Science.gov (United States)

    Wilder-Smith, Petra B. B.; Arrastia-Jitosho, Anna-Marie A.; Liaw, Lih-Huei L.; Berns, Michael W.

    1995-05-01

    Thermal and histological events resulting from soft tissue incision using CO2 lasers at 9.3 (mu) or 10.6 (mu) , fitted with a hollow wave guide or an articulated arm delivery system respectively, were investigated. In 9 fresh pigs' mandibles, standardized incisions 3 cm in length were made in the oral mucosa. Incisions were performed in the cw mode at 1 W, 4 W, and 12 W. Thermal events were measured in adjacent soft tissues using thermocouples. Incisions were dissected out, fixed, embedded in paraffin wax, sectioned and stained with Serius Red. The Students' t-test for paired data was used to compare zones of necrosis, zones of collagen damage and thermal events. No significant temperature rise was measured during irradiation at any timepoints or power settings (p < 0.05). Results were very similar for the two lasers with significantly different results obtained only at the 12 W setting (p < 0.05). Vertical incision depths and horizontal incision widths did not differ significantly (p < 0.0001) at 12 W and 4 W. Horizontal and vertical zones of necrosis did not differ significantly (p < 0.0001) either between the two lasers at 12 W and 4 W. Thus the thermal and histological events occurring during soft tissue incision were similar using these two lasers, despite the difference in wavelength and delivery system.

  4. Application of the low-level laser therapy for the treatment of vaginitis

    Science.gov (United States)

    Passeniouk, A. N.; Mikhailov, V. A.

    2000-06-01

    Vaginitis is the most common female infectious disease. Females suffering from this disorder are annually increasing in number. There are a lot of modalities of treatment of vaginitis, but because of drug allergy and microbe's stability to drug the treatment of vaginitis is difficult. Our study compares the efficacy of laser-therapy with drug therapy in the treatment of non-specific vaginitis and vaginal candidiasis. Thirty women reci4eed the LLLT by local action with antiseptic liquid daily during ten days, 20 women received metronidazole and fluconozole and vaginal application of metronidazole. The results suggest that local laser-therapy is able to remove sights of vaginitis more efficiently and faster than drug therapy. Repair of normal vaginal microflora, which is the best indicator of recovery, was significantly at a faster rate in laser-therapy group. There were no report of adverse reaction with vaginal laser- therapy, whereas there were women on drug therapy who reported side effects. In conclusion, vaginal aser-therapy with antiseptic liquid is a suitable, effective, safe and chip alternative to drug therapy in the treatment of vaginitis.

  5. Performance enhancement of ZnS:Mn thin film electroluminescent devices by combination of laser and thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Koutsogeorgis, Demosthenes C., E-mail: demosthenes.koutsogeorgis@ntu.ac.u [School of Science and Technology, Displays Research Group, Nottingham Trent University, Nottingham NG11 8NS (United Kingdom); Cranton, Wayne M.; Ranson, Robert M.; Thomas, Clive B. [School of Science and Technology, Displays Research Group, Nottingham Trent University, Nottingham NG11 8NS (United Kingdom)

    2009-08-26

    The combination of laser and thermal annealing was investigated as a post-deposition process for enhancing the luminescent properties of RF-magnetron sputtered ZnS:Mn thin film electroluminescent devices (TFEL). Laser annealing of the uncoated phosphor layer was performed using KrF excimer 248 nm laser pulses of 20 ns under an argon overpressure of 10 bar to limit laser ablation. Single, double and triple irradiation was applied at 1.4 J/cm{sup 2}. Thermal annealing was performed in vacuum at 500 deg. C and 550 deg. C for 1 h. In this paper we are reporting the brightness-voltage characteristics of devices that have been subjected to all combinations of the two annealing techniques (i.e. laser, thermal, laser + thermal, thermal + laser and finally non-annealed devices). Also, a simple lifetime comparison is made between the best performing device (laser + thermal) and the industrial standard (thermal). The lifetime (time to half brightness) and brightness of the best performing device is found to be more than double compared to the industrial standard.

  6. Thermal Ablation for Benign Thyroid Nodules: Radiofrequency and Laser

    Energy Technology Data Exchange (ETDEWEB)

    Baek, Jung Hwan; Lee, Jeong Hyun [University of Ulsan College of Medicine, Asan Medical Center, Seoul (Korea, Republic of); Valcavi, Roberto [Endocrinology Division and Thyroid Disease Center, Arcispedale Santa Maria Nuova, Reggio Emilia (Italy); Pacella, Claudio M. [Diagnostic Imaging and Interventional Radiology Department, Ospedale Regina Apostolorum, Albano Laziale-Rome (IT); Rhim, Hyun Chul [Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Na, Dong Kyu [Human Medical Imaging and Intervention Center, Seoul (Korea, Republic of)

    2011-10-15

    Although ethanol ablation has been successfully used to treat cystic thyroid nodules, this procedure is less effective when the thyroid nodules are solid. Radiofrequency (RF) ablation, a newer procedure used to treat malignant liver tumors, has been valuable in the treatment of benign thyroid nodules regardless of the extent of the solid component. This article reviews the basic physics, techniques, applications, results, and complications of thyroid RF ablation, in comparison to laser ablation.

  7. Thermal response of photovoltaic cell to laser beam irradiation

    OpenAIRE

    Yuan, Yu-Chen; Wu, Chen-Wu

    2014-01-01

    This paper firstly presents the concept of using dual laser beam to irradiate the photovoltaic cell, so as to investigate the temperature dependency of the efficiency of long distance energy transmission. Next, the model on the multiple reflection and absorption of any monochromatic light in multilayer structure has been established, and the heat generation in photovoltaic cell has been interpreted in this work. Then, the finite element model has been set up to calculate the temperature of ph...

  8. Assessment of thermal effects of interstitial laser phototherapy on mammary tumors using proton resonance frequency method

    Science.gov (United States)

    Le, Kelvin; Li, Xiaosong; Figueroa, Daniel; Towner, Rheal A.; Garteiser, Philippe; Saunders, Debra; Smith, Nataliya; Liu, Hong; Hode, Tomas; Nordquist, Robert E.; Chen, Wei R.

    2011-12-01

    Laser immunotherapy (LIT) uses a synergistic approach to treat cancer systemically through local laser irradiation and immunological stimulation. Currently, LIT utilizes dye-assisted noninvasive laser irradiation to achieve selective photothermal interaction. However, LIT faces difficulties treating deeper tumors or tumors with heavily pigmented overlying skin. To circumvent these barriers, we use interstitial laser irradiation to induce the desired photothermal effects. The purpose of this study is to analyze the thermal effects of interstitial irradiation using proton resonance frequency (PRF). An 805-nm near-infrared laser with an interstitial cylindrical diffuser was used to treat rat mammary tumors. Different power settings (1.0, 1.25, and 1.5 W) were applied with an irradiation duration of 10 min. The temperature distributions of the treated tumors were measured by a 7 T magnetic resonance imager using PRF. We found that temperature distributions in tissue depended on both laser power and time settings, and that variance in tissue composition has a major influence in temperature elevation. The temperature elevations measured during interstitial laser irradiation by PRF and thermocouple were consistent, with some variations due to tissue composition and the positioning of the thermocouple's needle probes. Our results indicated that, for a tissue irradiation of 10 min, the elevation of rat tumor temperature ranged from 8 to 11°C for 1 W and 8 to 15°C for 1.5 W. This is the first time a 7 T magnetic resonance imager has been used to monitor interstitial laser irradiation via PRF. Our work provides a basic understanding of the photothermal interaction needed to control the thermal damage inside a tumor using interstitial laser treatment. Our work may lead to an optimal protocol for future cancer treatment using interstitial phototherapy in conjunction with immunotherapy.

  9. Finite element thermal analysis for PMMA/st.st.304 laser direct joining

    Science.gov (United States)

    Hussein, Furat I.; Salloomi, Kareem N.; Akman, E.; Hajim, K. I.; Demir, A.

    2017-01-01

    This work is concerned with building a three-dimensional (3D) ab-initio models that is capable of predicting the thermal distribution of laser direct joining processes between Polymethylmethacrylate (PMMA) and stainless steel 304(st.st.304). ANSYS® simulation based on finite element analysis (FEA) was implemented for materials joining in two modes; laser transmission joining (LTJ) and conduction joining (CJ). ANSYS® simulator was used to explore the thermal environment of the joints during joining (heating time) and after joining (cooling time). For both modes, the investigation is carried out when the laser spot is at the middle of the joint width, at 15 mm from the commencement point (joint edge) at traveling time of 3.75 s. Process parameters involving peak power (Pp=3 kW), pulse duration (τ=5 ms), pulse repetition rate (PRR=20 Hz) and scanning speed (v=4 mm/s) are applied for both modes.

  10. Low power laser efficacy in the therapy of inflamed gingive in diabetics with parodontopathy

    Directory of Open Access Journals (Sweden)

    Obradović Radmila

    2011-01-01

    Full Text Available Background/Aim. There is clear evidence on direct relationship between periodontal disease and diabetes mellitus. Many investigations point out greater prevalence and severity of periodontal disease among diabetic patients. During last decade, low level laser therapy has been used in periodontal therapy. It has biostimulative effect, accelerates wound healing, minimizes pain and swelling, and there is almost no contraindication for its usage. The aim of the paper was to investigate the efficiency of low level laser therapy as adjuvant tool in reduction of gingival inflammation in diabetic patients. Methods. The study incuded 150 participants divided into three groups: group I (50 participants with diabetes mellitus type 1 and periodontal disease, group II (50 participants with diabetes mellitus type 2 and periodontal disease, group III (nondiabetic participants with periodontal disease. Gingival health evaluation was done using gingival index Löe-Silness. Soft and hard deposits were removed, periodontal pockets cleaned and GaAlAs low level laser therapy (5 mW applied five consecutive days. In each patient, low level laser therapy was not applied on the left side of the jaw in order to compare the effects of the applied therapy. After the first, third and fifth therapy and one month after the last visit gingival index was evaluated. Before the first and after the fifth therapy exfoliative cytology of gingiva was done and nuclei areal was analyzed morphometrically. Results. After all investigated periods, gingival index and nuclei areal were significantly decreased comparing to values before the therapy, at both jaw sides (p < 0.001. After the 1st, 3rd and 5th therapy, the t-test showed a significantly decreased gingival index at the lased side of jaw comparing to non-lased side. Conclusion. Low level laser therapy is efficient in gingival inflammation elimination and can be proposed as an adjuvant tool in basic periodontal therapy of diabetic

  11. Human percutaneous and intraoperative laser thermal angioplasty: initial clinical results as an adjunct to balloon angioplasty.

    Science.gov (United States)

    Sanborn, T A; Greenfield, A J; Guben, J K; Menzoian, J O; LoGerfo, F W

    1987-01-01

    In this study, the safety and efficacy of percutaneous laser thermal angioplasty as an adjunct to balloon angioplasty were investigated in 13 patients with severe peripheral vascular disease. By means of a novel fiberoptic laser delivery system (Laserprobe) in which argon laser energy is converted to heat in a metallic tip at the end of the fiberoptic fiber, improvement in the angiographic luminal diameter was noted in 14 of 15 femoropopliteal vessels (93%) by delivering 8 to 13 watts of continuous argon laser energy as the Laserprobe was advanced through the lesion. Initial clinical success (indicated by relief of symptoms and increase in Doppler index) for the combined laser and balloon angioplasty procedures was obtained in 12 of 15 vessels (80%), with inadequate balloon dilatation being the limiting factor in three patients. No significant complications of vessel perforation, dissection, pain, spasm, or embolization of debris occurred. Of the 12 patients who had procedures with initial angiographic and clinical success, 10 (83%) were asymptomatic in the initial follow-up period of 1 to 9 months (mean 6 months). Thus, laser thermal angioplasty with a Laserprobe is a safe and effective adjunct to peripheral balloon angioplasty. This technique has the potential to increase the initial success rate of angioplasty for lesions that are difficult or impossible to treat by conventional means. By removing most of the obstructing lesion, this technique may also reduce recurrent stenosis.

  12. Helium-neon laser therapy in the treatment of hydroxyapatite orbital implant exposure: A superior option.

    Science.gov (United States)

    Xu, Qi-Hua; Zhao, Chen; Zhu, Jian-Gang; Chen, Mei-Juan; Liu, Qing-Huai

    2015-09-01

    The aim of the present study was to evaluate the efficacy of helium-neon laser therapy in the treatment of hydroxyapatite orbital implant exposure and compare the results with those of a combined drugs and surgery regimen. A total of 70 patients with hydroxyapatite orbital implant exposure in 70 eyes were randomly divided into two groups: Helium-neon laser therapy (group A) and drugs plus surgery (group B). Each group contained 35 patients. The healing rates and times of the conjunctival wound were recorded and compared following helium-neon laser treatment or the drugs plus surgery regimen. Changes in the hydroxyapatite orbital implant prior to and following helium-neon laser irradiation were analyzed. A similar animal study was conducted using 24 New Zealand white rabbits, which received orbital implants and were then received drug treatment or helium-neon therapy. In the human experiment, the rates for conjunctival wound healing were 97.14% in group A and 74.29% in group B, with a significant difference between the groups (χ(2)=5.71, Phelium-neon laser therapy and 14.33±3.20 days of drugs plus surgery. A statistically significant difference was found between the groups (t=8.97, Phelium-neon laser therapy and 31.25±4.21 days of drugs plus surgery. The difference between the groups was statistically significant (t=7.91, Phelium-neon laser therapy significantly promoted vascularization of the hydroxyapatite orbital implant. These results, combined with pathological findings in animals, which showed that a helium-neon laser promoted vascularization and had anti-inflammatory effects, suggest that helium-neon laser irradiation is an effective method for treating hydroxyapatite orbital implant exposure, thereby avoiding secondary surgery.

  13. Negative-index gratings formed by femtosecond laser overexposure and thermal regeneration.

    Science.gov (United States)

    He, Jun; Wang, Yiping; Liao, Changrui; Wang, Chao; Liu, Shen; Yang, Kaiming; Wang, Ying; Yuan, Xiaocong; Wang, Guo Ping; Zhang, Wenjing

    2016-03-16

    We demonstrate a method for the preparation of negative-index fibre Bragg gratings (FBGs) using 800 nm femtosecond laser overexposure and thermal regeneration. A positive-index type I-IR FBG was first inscribed in H2-free single-mode fibre using a femtosecond laser directed through a phase mask, and then a highly polarization dependant phase-shifted FBG (P-PSFBG) was fabricated from the type I-IR FBG by overexposure to the femtosecond laser. Subsequently, the P-PSFBG was thermally annealed at 800 °C for 12 hours. Grating regeneration was observed during thermal annealing, and a negative-index FBG was finally obtained with a high reflectivity of 99.22%, an ultra-low insertion loss of 0.08 dB, a blueshift of 0.83 nm in the Bragg wavelength, and an operating temperature of up to 1000 °C for more than 10 hours. Further annealing tests showed that the thermal stability of the negative-index FBG was lower than that of a type II-IR FBG, but much higher than that of a type I-IR FBG. Moreover, the formation of such a negative-index grating may result from thermally regenerated type IIA photosensitivity.

  14. Thermal signature measurements for ammonium nitrate/fuel mixtures by laser heating

    Energy Technology Data Exchange (ETDEWEB)

    Nazarian, Ashot; Presser, Cary, E-mail: cpresser@nist.gov

    2016-01-10

    Highlights: • LDTR is a useful diagnostic for characterizing AN/fuel mixture thermochemical behavior. • Each AN/fuel mixture thermal signature was different. • AN/fuel mixture signature features were defined by the individual constituents. • Baseline signatures changed after an experiment. - Abstract: Measurements were carried out to obtain thermal signatures of several ammonium nitrate/fuel (ANF) mixtures, using a laser-heating technique referred to as the laser-driven thermal reactor (LDTR). The mixtures were ammonium nitrate (AN)/kerosene, AN/ethylene glycol, AN/paraffin wax, AN/petroleum jelly, AN/confectioner's sugar, AN/cellulose (tissue paper), nitromethane/cellulose, nitrobenzene/cellulose, AN/cellulose/nitromethane, AN/cellulose/nitrobenzene. These mixtures were also compared with AN/nitromethane and AN/diesel fuel oil, obtained from an earlier investigation. Thermograms for the mixtures, as well as individual constituents, were compared to better understand how sample thermal signature changes with mixture composition. This is the first step in development of a thermal-signature database, to be used along with other signature databases, to improve identification of energetic substances of unknown composition. The results indicated that each individual thermal signature was associated unambiguously with a particular mixture composition. The signature features of a particular mixture were shaped by the individual constituent signatures. It was also uncovered that the baseline signature was modified after an experiment due to coating of unreacted residue on the substrate surface and a change in the reactor sphere oxide layer. Thus, care was required to pre-oxidize the sphere prior to an experiment. A minimum sample mass (which was dependent on composition) was required to detect the signature characteristics. Increased laser power served to magnify signal strength while preserving the signature features. For the mixtures examined, the thermal

  15. Thermal transport in CO2 laser irradiated fused silica: in situ measurements and analysis

    Energy Technology Data Exchange (ETDEWEB)

    Yang, S T; Matthews, M J; Elhadj, S; Draggoo, V G; Bisson, S E

    2009-07-07

    In situ spatial and temporal temperature measurements of pristine fused silica surfaces heated with a 10.6 {micro}m CO{sub 2} laser were obtained using an infrared radiation thermometer based on a Mercury Cadmium Telluride (MCT) camera. Laser spot sizes ranged from 250 {micro}m to 1000 {micro}m diameter with peak axial irradiance levels of 0.13 to 16 kW/cm{sup 2}. For temperatures below 2800K, the measured steady-state surface temperature is observed to rise linearly with both increasing beam size and incident laser irradiance. The effective thermal conductivity estimated over this range was approximately 2W/mK, in good agreement with classical calculations based on phonon heat capacities. Similarly, time-dependent temperature measurements up to 2000K yielded thermal diffusivity values which were close to reported values of 7 x 10{sup -7} m{sup 2}/s. Above {approx}2800K, the fused silica surface temperature asymptotically approaches 3100K as laser power is further increased, consistent with the onset of evaporative heat losses near the silica boiling point. These results show that in the laser heating regime studied here, the T{sup 3} temperature dependent thermal conductivity due to radiation transport can be neglected, but at temperatures above 2800K heat transport due to evaporation must be considered. The thermal transport in fused silica up to 2800K, over a range of conditions, can then be adequately described by a linear diffusive heat equation assuming constant thermal properties.

  16. Red diode laser for photodynamic therapy: a small animal efficacy study

    Science.gov (United States)

    Lytle, A. Charles; Doiron, Daniel R.; Selman, Steven H.

    1994-07-01

    Lasers have traditionally been the preferred light source for activation of the photosensitizing agents used in photodynamic therapy (PDT). Their monochromaticity, high power, and the ability to efficiently couple that power into optical fibers have dictated their use. Dye lasers, metal vapor lasers, or ion gas lasers have been used in the past as the excitation source for PDT, largely because they provided the only available alternatives. These laser systems are very large and complex, and are very expensive to operate. The introduction of high power visible red laser diodes have provided a cost effective alternative to existing lasers for use in PDT. This paper will describe the features of a prototype preclinical red laser diode source for photodynamic therapy, and will present the results of an animal study conducted with this device. The study, using the photosensitizer SnET2, compared the efficacy of PDT performed with the diode laser system with the results obtained from a traditional dye laser system. Future plans for a clinical version of the system will also be discussed.

  17. Thermal degradation of ultrabroad bismuth NIR luminescence in bismuth-doped tantalum germanate laser glasses.

    Science.gov (United States)

    Wang, Liping; Zhao, Yanqi; Xu, Shanhui; Peng, Mingying

    2016-04-01

    Because of ultra-broadband luminescence in 1000-1700 nm and consequent applications in fiber amplifier and lasers in the new spectral range where traditional rare earth cannot work, bismuth-doped laser glasses have received rising interest recently. For long-term practical application, thermal degradation must be considered for the glasses. This, however, has seldom been investigated. Here we report the thermal degradation of bismuth-doped germanate glass. Heating and cooling cycle experiments at high temperature reveal strong dependence of the thermal degradation on glass compositions. Bismuth and tantalum lead to the reversible degradation, while lithium can produce permanent irreversible degradation. The degradation becomes worse as lithium content increases in the glass. Absorption spectra show this is due to partial oxidation of bismuth near-infrared emission center. Surprisingly, we notice the emission of bismuth exhibits blueshift, rather than redshift at a higher temperature, and the blueshift can be suppressed by increasing the lithium content.

  18. Heat Transfer Analysis on Laser-tissue Thermal Interaction Using Heterogeneous Model

    Institute of Scientific and Technical Information of China (English)

    LI Hejie; ZHANG Xuexue; LIU Jing

    2002-01-01

    Considering the heterogeneous thermal properties of living tissues,a multi-layer heat transfer model for laser-tissue thermal interaction is presented in this paper.An analytical solution to the temperature transients within two tissue layers is obtained using the Laplace integral transform method.Heat transfer behaviors inside the tissues before evaporation are investigated.The critical time required to vaporize the surface tissue and the thermal damage depth are numerically predicted.It was shown that there is evident difference in temperature predictions between the uniform model and the heterogeneous one.This study is useful to laser surgery,such as ophthalmology,dermatology and neurosurgery which request high accuracy on temperature prediction and heat deposition.

  19. Ultrafast thermal dynamics of nano-ripples formation via laser double pulses excitation

    Science.gov (United States)

    Du, Guangqing; Wu, Yanmin; Uddin, Noor; Yang, Qing; Chen, Feng; Lu, Yu; Bian, Hao; Hou, Xun

    2016-09-01

    The ultrafast thermal dynamics of nano-ripples formation on gold film via ultrafast laser double pulses excitation is theoretically investigated by numerical simulations. The non-equilibrium thermal modulations with respect to the electron and phonon energy transfers within gold film is proposed for predicting the nano-ripples formation. It is revealed that the nano-ripples contrast on gold film surface can be well controlled via tuning the pulse energy ratio, pulse separation and pulse exchange of ultrafast laser double-pulse. It is attributed to the tunable energy transfer routes between the electron thermal diffusion and the electron-phonon coupling via tuning double pulses parameters. The study provides theoretical basis for producing high-contrast ripples for a wide range application in the fields such as high-absorptive solar cells, surface friction devices and super-hydrophobic surface.

  20. Pulse laser head with monolithic thermally bonded microchip operating at 1.5 μm wavelength

    Science.gov (United States)

    Młyńczak, Jarosław; Kopczyński, Krzysztof; Belghachem, Nabil; Kisielewski, Jarosław; Stepień, Ryszard; Wychowaniec, Marek; Galas, Jacek; Litwin, Dariusz; CzyŻewski, Adam

    2016-12-01

    On the basis of thermally bonded Er,Yb:glass/Co:MALO microchip a laser head pumped by fiber coupled laser diode was designed. The performance of the laser head were investigated and the main output parameters were determined. The energy over 40 μJ in 3.8 ns pulse with repetition rate of 0.735 kHz was achieved. The laser head characterized by such parameters can successfully be used in tele-detection applications.

  1. Medication-Related Osteonecrosis of Jaws: A Low-Level Laser Therapy and Antimicrobial Photodynamic Therapy Case Approach

    OpenAIRE

    2016-01-01

    Medication-related osteonecrosis of the jaws (MRONJ) can be considered an inability of the alveolar bone to respond to an injury, which frequently leads to severe local and systemic complications. Once the problem is installed, dentist must use all therapeutic approaches recommended. This manuscript reports a successful management of MRONJ handled with antibiotics, conservative debridement, low-level laser therapy (LLLT), and photodynamic therapy (PDT) up to 12 months. As healing of MRONJ may...

  2. A high power lamp-pumped LNA laser with thermally tuned etalon

    Science.gov (United States)

    Aminoff, C. G.; Essabaa, S.; Brissaud, I.; Arianer, J.

    1991-11-01

    This report describes arc-lamp pumped, tunable, continuous-wave LNA laser with improved output efficiency, suitable for optical pumping of helium. Using thermal tuning of intracavity etalons instead of angle tuning reduces losses caused by walk-off effects and provides continuous frequency scanning without a significant decrease in laser power. We obtain an output power of 4 W in a linewidth of 2.5 GHz with the laser wavelength tuned to the 1.083 μm absorption line of metastable helium. This result represents a fourfold gain in efficiency compared with conventional tuning by tilting. The laser provides efficient polarization of helium by optical pumping in various applications, such as nuclear spin polarization of 3He and spin-polarized electron sources.

  3. Thermal tuning of volume Bragg gratings for spectral beam combining of high-power fiber lasers.

    Science.gov (United States)

    Drachenberg, Derrek R; Andrusyak, Oleksiy; Venus, George; Smirnov, Vadim; Glebov, Leonid B

    2014-02-20

    High-radiance lasers are desired for many applications in defense and manufacturing. Spectral beam combining (SBC) by volume Bragg gratings (VBGs) is a very promising method for high-radiance lasers that need to achieve 100 kW level power. Laser-induced heating of VBGs under high-power radiation presents a challenge for maintaining Bragg resonance at various power levels without mechanical realignment. A novel thermal tuning technique and apparatus is presented that enables maintaining peak efficiency operation of the SBC system at various power levels without any mechanical adjustment. The method is demonstrated by combining two high-power ytterbium fiber lasers with high efficiency from low power to full combined power of 300 W (1.5 kW effective power), while maintaining peak combining efficiency within 0.5%.

  4. Meta-analysis on intravascular low energy laser therapy

    Science.gov (United States)

    Zhao, Shu-Dong; Liu, Timon Cheng-Yi; Wang, Yan-Fang; Liu, Song-Hao

    2008-12-01

    Intravascular low energy laser therapy (ILELT) was put forward for cardiocirculatory diseases in USA in 1982, was popular in Russia in 1980s, and then in China in 1990s. The therapeutic effects of ILELT and drugs in comparison with drugs only on Chinese patients and their blood parameters were analyzed with meta-analyses and reported as (OR, 95%CI) for patient improvement and (WMD, 95% CI) for blood parameter improvement, where 95%CI, OR and WMD denoted 95% confidence intervals, odds ratio and weighted mean difference, respectively. It was found that the patients of cerebral infarction (2.39, 2.09~2.74) and cerebrovascular diseases (2.97, 1.69~2.53) were cured, respectively, (P low density lipoprotein cholesterol (-0.6, -1.01~-0.19), triacylglycerol (0.63, -0.83~-0.42), high density lipoprotein (0.34, 0.10~0.59), erythrocyte aggregation index (-0.24, -0.27~-0.21), erythrocyte Sedimentation Rate (-4.57, -7.26~-1.89), fibrinogen (-0.76, -1.31~-0.21), whole blood contrast viscosity (-0.40, -0.69~-0.12), low cut blood viscosity (-1.2, -1.93~-0.48), high cut blood viscosity (-0.62, -0.92~-0.32), whole blood viscosity(-1.2, -1.85~-0.54) and plasma blood contrast viscosity(-0.07, -0.12~-0.03) were found improved (P < 0.05). It is concluded that the patients of cerebral infarction, cerebrovascular diseases and diabetes might be improved with ILELT, which might be mediated by blood parameter improvement.

  5. Thermal rocketing and the Laser Geodynamic Satellite (LAGEOS-1)

    Energy Technology Data Exchange (ETDEWEB)

    Miller, W.A.

    1997-08-01

    This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory. LAGEOS is the most accurately tracked satellite in orbit. It is a totally passive, dense spherical satellite covered with 426 cube corner reflectors. Besides its great utility in measuring the Earth`s length of day and polar wobble, this satellite can be used to measure, for the first time, the general relativistic frame-dragging effect. Of the five dominant error sources in such an experiment, the largest one involves surface interaction of thermal forces (thermal rocketing) and its influence on the orbital nodal precession. The project objective was to enhance an already available theoretical model (computer code) developed at Los Alamos based on new optical-spin data obtained at the University of Maryland. The project objective was met and the enhanced code will serve as the new spin-dynamics model for future LAGEOS satellite missions.

  6. Thermalization time of thin metal film heated by short pulse laser

    Institute of Scientific and Technical Information of China (English)

    Xu Hong-Yu; Zhang Yuan-Chong; Song Ya-Qin; Chen Dian-Yun

    2004-01-01

    Based on the hyperbolic two-step heat conduction model, using the Laplace transform and numerical inverse transform method (Riemann-sum approximation method), the thermal behaviour of thin metal films has been studied during femtosecond pulse laser heating. Also the thermalization time, which is the time for the electron gas and solid lattice to reach thermal balance, has been studied in detail. The values of thermalization time for silver (Ag), gold (Au),copper (Cu) and lead (Pb) are obtained. The effects of material parameters of the thin metal film on the thermalization time are considered for the four kinds of metals by changing one of the parameters and regarding the other parameters as constant. For a typical metal material, the order of the thermalization time is of the order of hundreds of picoseconds.The thermalization time decays exponentially with the increase of phonon-electron coupling factor or electron gas thermal conductivity, and it increases linearly with the increase of the ratio of lattice heat capacity to electron gas heat capacity. However, the relaxation time of the electron gas has very little effect on the thermalization time.

  7. Thermalization time of thin metal film heated by short pulse laser

    Science.gov (United States)

    Xu, Hong-Yu; Zhang, Yuan-Chong; Song, Ya-Qin; Chen, Dian-Yun

    2004-10-01

    Based on the hyperbolic two-step heat conduction model, using the Laplace transform and numerical inverse transform method (Riemann-sum approximation method), the thermal behaviour of thin metal films has been studied during femtosecond pulse laser heating. Also the thermalization time, which is the time for the electron gas and solid lattice to reach thermal balance, has been studied in detail. The values of thermalization time for silver (Ag), gold (Au), copper (Cu) and lead (Pb) are obtained. The effects of material parameters of the thin metal film on the thermalization time are considered for the four kinds of metals by changing one of the parameters and regarding the other parameters as constant. For a typical metal material, the order of the thermalization time is of the order of hundreds of picoseconds. The thermalization time decays exponentially with the increase of phonon-electron coupling factor or electron gas thermal conductivity and it increases linearly with the increase of the ratio of lattice heat capacity to electron gas heat capacity. However, the relaxation time of the electron gas has very little effect on the thermalization time.

  8. Laser Therapy Inhibits Tumor Growth in Mice by Promoting Immune Surveillance and Vessel Normalization

    Directory of Open Access Journals (Sweden)

    Giulia Ottaviani

    2016-09-01

    Full Text Available Laser therapy, recently renamed as photobiomodulation, stands as a promising supportive treatment for oral mucositis induced by oncological therapies. However, its mechanisms of action and, more importantly, its safety in cancer patients, are still unclear. Here we explored the anti-cancer effect of 3 laser protocols, set at the most commonly used wavelengths, in B16F10 melanoma and oral carcinogenesis mouse models. While laser light increased cell metabolism in cultured cells, the in vivo outcome was reduced tumor progression. This striking, unexpected result, was paralleled by the recruitment of immune cells, in particular T lymphocytes and dendritic cells, which secreted type I interferons. Laser light also reduced the number of highly angiogenic macrophages within the tumor mass and promoted vessel normalization, an emerging strategy to control tumor progression. Collectively, these results set photobiomodulation as a safety procedure in oncological patients and open the way to its innovative use for cancer therapy.

  9. Patient's evaluation of argon laser therapy of port wine stain, decorative tattoo, and essential telangiectasia.

    Science.gov (United States)

    Dixon, J A; Rotering, R H; Huether, S E

    1984-01-01

    One hundred fourteen patients were studied to assess their perception of the results of argon laser therapy for port wine stains (PWS), tattoos, or essential telangiectasia of legs. At least 1 yr following treatment patients were surveyed using a 30-item mail questionnaire. A 91% response rate was achieved. The findings indicate that patients with PWS and tattoo treated with argon laser are moderately satisfied with the results and 85% of them would have treatment again. Laser therapy of these lesions should be continued. Treatment results of essential telangiectasia of the legs are disappointing and only 49% of patients would have treatment again. Discontinuance of argon laser therapy using the described techniques is recommended.

  10. Low-level laser therapy of dentin hypersensitivity: a short-term clinical trial.

    Science.gov (United States)

    Orhan, Kaan; Aksoy, Umut; Can-Karabulut, Deniz C; Kalender, Atakan

    2011-09-01

    The aim of this study was to evaluate low-level laser therapy in cervical dentin hypersensitivity. A randomized controlled clinical trial was conducted with a total of 64 teeth. Dentin desensitizer and diode laser were applied on the cervical dentin surfaces. Distilled water and placebo laser was used as the placebo groups. The irradiance used was 4 J/cm(2) per treatment site. The baseline measurement of hypersensitivity was made by using visual analog scale (VAS). Twenty-four hours and 7 days after the application of desensitizer, diode laser and placebo groups, a new VAS analysis was conducted for the patients' sensitivity level. The mean pain scores of placebo groups were significantly higher than the desensitizer's and diode laser's mean scores (ANOVA, p low-level laser therapy and no statistically significant difference was observed between these two treatments (p > 0.05). Although low-level laser and glutaraldehyde containing desensitizer present distinct modes of action, experimental agents caused a significant reduction of dentin hypersensitivity without showing secondary effects, not irritating the pulp or causing pain, not discoloring or staining the teeth, and not irritating the soft tissues at least for a period of 1 week with no drawbacks regarding handling and/or ease of application. Low-level laser therapy and desensitizer application had displayed similar effectiveness in reducing moderate dentin hypersensitivity.

  11. Thermal and optical modeling of "blackened" tips for diode laser surgery

    Science.gov (United States)

    Belikov, Andrey V.; Skrypnik, Alexei V.; Kurnyshev, Vadim Y.

    2016-04-01

    This paper presents the results of thermal and optical modeling of "blackened" tips (fiber-optic thermal converter) with different structures: film and volumetric. Film converter is created by laser radiation action on a cork or paper and it is a one-step process. As a result, a carbonized cork or paper adhered to the distal end of the optical fiber absorbs light that leads to heating of the distal end of the optical fiber. We considered the peculiarities of volumetric converters formed by sintering (second step) of the target material transferred to the tip, at irradiating the target with laser radiation (first step). We investigated the interaction between 980 nm laser radiation and converters in the air and water. As a result of experiments and modeling, it was obtain, that converter temperature and power of converter destruction depend on the environment in which it is placed. We found that film converter in the air at average power of laser radiation of 0.30+/-0.05 W is heated to 900+/-50°C and destructed, and volumetric converter in the air at average power of laser radiation of 1.0+/-0.1 W is heated to 1000+/-50°C and destructed at reaching of 4.0+/-0.1 W only. We found that film converter in the water at average power of laser radiation of 1.0+/-0.1 W is heated to 550+/-50°C and destructed at reaching of 4.0+/-0.1 W only. Volumetric converter at average power of laser radiation of4.0+/-0.1 W is heated to 450+/-50°C and is not destructed up to 7.5+/-0.1 W, it is heated to 500+/-50°C in this case. Thus, volumetric converter is more resistant to action of laser heating.

  12. Use of a microsecond Er:YAG laser in laryngeal surgery reduces collateral thermal injury in comparison to superpulsed CO2 laser.

    Science.gov (United States)

    Böttcher, Arne; Jowett, Nathan; Kucher, Stanislav; Reimer, Rudolph; Schumacher, Udo; Knecht, Rainald; Wöllmer, Wolfgang; Münscher, Adrian; Dalchow, Carsten V

    2014-05-01

    Despite causing significant thermocoagulative insult, use of the carbon dioxide (CO2) laser is considered gold standard in surgery for early stage larynx carcinoma. Limited attention has been paid to the use of the erbium:yttrium-aluminium-garnet (Er:YAG) laser in laryngeal surgery as a means to reduce thermal tissue injury. The objective of this study is to compare the extent of thermal injury and precision of vocal fold incisions made using microsecond Er:YAG and superpulsed CO2 lasers. In the optics laboratory ex vivo porcine vocal folds were incised using Er:YAG and CO2 lasers. Lateral epithelial and subepithelial thermal damage zones and cutting gap widths were histologically determined. Environmental scanning electron microscopy (ESEM) images were examined for signs of carbonization. Temperature rise during Er:YAG laser incisions was determined using infrared thermography (IRT). In comparison to the CO2 laser, Er:YAG laser incisions showed significantly decreased epithelial (236.44 μm) and subepithelial (72.91 μm) damage zones (p CO2 (878.72 μm) compared to Er:YAG (1090.78 μm; p = 0.027) laser. ESEM revealed intact collagen fibres along Er:YAG laser cutting edges without obvious carbonization, in comparison to diffuse carbonization and tissue melting seen for CO2 laser incisions. IRT demonstrated absolute temperature rise below 70 °C for Er:YAG laser incisions. This study has demonstrated significantly reduced lateral thermal damage zones with wider basal cutting gaps for vocal fold incisions made using Er:YAG laser in comparison to those made using CO2 laser.

  13. Clinical effect of anti-VEGF drugs combined with laser therapy for DME patients

    Directory of Open Access Journals (Sweden)

    Li Yin

    2017-06-01

    Full Text Available AIM:To investigate the clinical effect of anti-vascular endothelial growth factor(VEGFdrugs combined with laser photocoagulation for diabetic macular edema(DME. METHODS: Totally 94 patients(141 eyeswith DME from June to December 2015 in our hospital were selected and randomly divided into combined group of 47 cases(68 eyes, ranibizumab combined with laser therapyand the control group of 47 cases(73 eyes, laser treatment. The levels of best corrected visual acuity(BCVA, macular central retinal thickness(CRT, total macular volume(TMVand macular edema level were compared between the two groups at different time after treatment. RESULTS: The mean values of BCVA in the combined group were higher than those in the control group at 2, 6 and 12wk, and the difference was statistically significant(PPPCONCLUSION: The effect of anti-VEGF drugs combined with laser therapy for DME patients is better than that of single laser therapy alone.

  14. A new, efficient laser source at 630 nm for photodynamic therapy and pulsed hologram

    Energy Technology Data Exchange (ETDEWEB)

    Azzeer, Abdallah M.; Masilamani, Vadivel [King Saud University, College of Science, Riyadh (Saudi Arabia)

    2003-02-01

    This paper gives details of a new, simple and efficient laser source at 630 nm with an average power of 300 mW, based on stimulated Raman scattering (SRS) from an organic liquid, and with the second harmonic of a Nd:YAG laser as a pump source. What we have developed here can be fabricated as a module that can be added to a Nd:YAG laser, commonly available in laser clinics, for an effective photodynamic therapy (PDT) of caner. The same source would become a convenient tool for a pulsed hologram. (author)

  15. Thermal distribution analysis of multi-core photonic crystal fiber laser

    Institute of Scientific and Technical Information of China (English)

    ZHENG Yi-bo; YAO Jian-quan; ZHANG Lei; WANG Yuan; WEN Wu-qi; JING Lei; DI Zhi-gang; KANG Jian-yi

    2012-01-01

    The thermal properties of photonic crystal fiber (PCF) laser with 18 circularly distributed cores are investigated by using full-vector finite element method (FEM).The results show that the 18-core PCF has a more effective thermal dispersion construction compared with the single core PCF and 19-core PCF.In addition,the temperature distribution of 18-core PCF laser with different thermal loads is simulated.The results show that the core temperature approaches the fiber drawing value of 1800 K approximately when the thermal load is above 80 W/m which corresponds to the pumping power of 600 W approximately,while the coating temperature approaches the damage value of about 550 K when the thermal load is above 15 W/m which corresponds to the pumping power of 110 W approximately.Therefore the fiber cooling is necessary to achieve power scaling.Compared with other different cooling systems,the copper cooling scheme is found to be an effective method to reduce the thermal effects.

  16. Thermal impact of near-infrared laser in advanced noninvasive optical brain imaging.

    Science.gov (United States)

    Nourhashemi, Mina; Mahmoudzadeh, Mahdi; Wallois, Fabrice

    2016-01-01

    The propagation of laser light in human tissues is an important issue in functional optical imaging. We modeled the thermal effect of different laser powers with various spot sizes and different head tissue characteristics on neonatal and adult quasirealistic head models. The photothermal effect of near-infrared laser (800 nm) was investigated by numerical simulation using finite-element analysis. Our results demonstrate that the maximum temperature increase on the brain for laser irradiance between 0.127 (1 mW) and [Formula: see text] (100 mW) at a 1 mm spot size, ranged from 0.0025°C to 0.26°C and from 0.03°C to 2.85°C at depths of 15.9 and 4.9 mm in the adult and neonatal brain, respectively. Due to the shorter distance of the head layers from the neonatal head surface, the maximum temperature increase was higher in the neonatal brain than in the adult brain. Our results also show that, at constant power, spot size changes had a lesser heating effect on deeper tissues. While the constraints for safe laser irradiation to the brain are dictated by skin safety, these results can be useful to optimize laser parameters for a variety of laser applications in the brain. Moreover, combining simulation and adequate in vitro experiments could help to develop more effective optical imaging to avoid possible tissue damage.

  17. Enhanced spectrum superluminescent diodes fabricated by infrared laser rapid thermal annealing

    Science.gov (United States)

    Beal, Romain; Moumanis, Khalid; Aimez, Vincent; Dubowski, Jan J.

    2013-12-01

    We report on the fabrication of superluminescent diodes (SLD) from a graded bandgap quantum well intermixed (QWI) material obtained by an infrared laser rapid thermal annealing (IR Laser-RTA) technique. The processed semiconductor wafer consisted of an InGaAs/InGaAsP/InP (001) QW laser heterostructure originally emitting at 1.55 μm. The combined beams of a 150 W laser diode operating at 980 nm and a 30 W Nd:YAG laser operating at 1064 nm are used to heat the sample. While the laser diode is used for back-side heating of the wafer, the Nd:YAG laser beam is swept along the sample surface, resulting in temperature gradient changing in the direction perpendicular to the scan. This contactless RTA approach, allowed to obtain a graded bandgap material that was employed for the fabrication of SLD devices with a broadened emission bandwidth. The lasing effect in a series of 3 mm long broad area injection diodes was suppressed by tilting their facets by 7.5° with respect to the [110] direction. The best SLD devices had their FWHM (full-width-at-half-maximum) emission increased by 33% in comparison to the FWHM of 36 nm observed for devices made from the as grown material at an equal output power of 0.8 mW.

  18. Testing relativity again, laser, laser, laser, laser

    NARCIS (Netherlands)

    Einstein, A.

    2015-01-01

    laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser,

  19. Use of Low Level Laser Therapy for Oral Lichen Planus: Report of Two Cases

    Directory of Open Access Journals (Sweden)

    Mahdavi O.

    2013-12-01

    Full Text Available Oral Lichen Planus is a chronic inflammatory disease of unknown etiology. Erosive/ ulcerative oral lichen planus is often a painful condition that tends to become malignant, urging appropriate therapy. Laser therapy has recently been suggested as a new treatment option without significant side effects. This article presents two cases of erosive/ ulcerative oral lichen planus, who had not received any treatment before, treated with 630 nm low level laser. Lesion type and pain was recorded before and after treatment. Severity of lesions and pain were reduced after treatment. Low Level Laser Therapy was an effective treatment with no side effects and it may be considered as an alternative therapy for erosive/ulcerative oral lichen planus.

  20. Use of low level laser therapy for oral lichen planus: report of two cases.

    Science.gov (United States)

    Mahdavi, O; Boostani, N; Jajarm, Hh; Falaki, F; Tabesh, A

    2013-12-01

    Oral Lichen Planus is a chronic inflammatory disease of unknown etiology. Erosive/ ulcerative oral lichen planus is often a painful condition that tends to become malignant, urging appropriate therapy. Laser therapy has recently been suggested as a new treatment option without significant side effects. This article presents two cases of erosive/ ulcerative oral lichen planus, who had not received any treatment before, treated with 630 nm low level laser. Lesion type and pain was recorded before and after treatment. Severity of lesions and pain were reduced after treatment. Low Level Laser Therapy was an effective treatment with no side effects and it may be considered as an alternative therapy for erosive/ulcerative oral lichen planus.

  1. Multifocal Gastric Neoplasia after Recurrent Laser Therapy for the Watermelon Stomach

    Directory of Open Access Journals (Sweden)

    Charles N Bernstein

    1997-01-01

    Full Text Available Repeated laser therapy has become an accepted therapeutic approach in the treatment of watermelon stomach, and to date no important negative sequelae have been reported. The case of a patient who underwent repeated sessions of neodymium: yttrium aluminum garnet (Nd:YAG laser therapy over a five-year period for the treatment of the watermelon stomach is presented. Postlaser therapy the patient developed deep ulcerations that would heal; however, he ultimately developed a nodular antrum. Random biopsies of antral nodules revealed carcinoma-in-situ. A Billroth I gastrectomy revealed two foci of carcinoma-in-situ/high grade dysplasia and multiple foci of lower grades of dysplasia. This case suggests a possible association between use of laser therapy and development of gastric neoplasia.

  2. DEVICE FOR MEASURING OF THERMAL LENS PARAMETERS IN LASER ACTIVE ELEMENTS WITH A PROBE BEAM METHOD

    Directory of Open Access Journals (Sweden)

    A. N. Zakharova

    2015-01-01

    Full Text Available We have developed a device for measuring of parameters of thermal lens (TL in laser active elements under longitudinal diode pumping. The measurements are based on the probe beam method. This device allows one to determine sign and optical power of the lens in the principal meridional planes, its sensitivity factor with respect to the absorbed pump power and astigmatism degree, fractional heat loading which make it possible to estimate integral impact of the photoelastic effect to the formation of TL in the laser element. The measurements are performed in a linearly polarized light at the wavelength of 532 nm. Pumping of the laser element is performed at 960 nm that makes it possible to study laser materials doped with Yb3+ and (Er3+, Yb3+ ions. The precision of measurements: for sensitivity factor of TL – 0,1 m-1/W, for astigmatism degree – 0,2 m-1/W, for fractional heat loading – 5 %, for the impact of the photoelastic effect – 0,5 × 10-6 K-1. This device is used for characterization of thermal lens in the laser active element from an yttrium vanadate crystal, Er3+,Yb3+:YVO .

  3. Effect of laser remelting on the tribological performance of thermal barrier coatings.

    Science.gov (United States)

    Rico, A; Sevillano, F; Múnez, C J; López, M D; Utrilla, V; Rodríguez, J; Poza, P

    2012-06-01

    Gas turbine's efficiency improves as operating temperature is increased. For this reason, metallic components used in turbine engines, for propulsion and power generation, are protected by thermal barrier coatings (TBC). Laser glazing has been used to enhance the oxidation and corrosion resistance of thermally sprayed TBC, but there is no information about the effect of this treatment on the tribological performance. ZrO2(CaO) top coat and NiAIMo bond coating were flame sprayed onto an AlSI 1045 carbon steel. The top coat was laser remelted and a densified ceramic layer was induced in the top surface of the ceramic coating. Both, the as sprayed and the laser remelted top coatings, were formed by cubic ZrO2 with some tetragonal precipitates. The grain size was reduced by the laser treatment. The mechanical properties and the local wear rate were evaluated by depth sensing indentation and scratch tests respectively. The nanoscale wear behaviour was always improved by the laser treatment.

  4. Low-Level Laser Therapy in Russia: History, Science and Practice

    Science.gov (United States)

    Moskvin, Sergey Vladimirovich

    2017-01-01

    In Russia (formerly USSR) study of biomodulation action (BMA) mechanisms of low-intensity laser irradiation (LILI) began in 1964, immediately after the development of lasers. During the period from 1965 to 1972 several dozens of scientific conferences were held, hundreds of studies were published. Generally, secondary mechanisms and results of LILI effect on patients with various diseases were studied. This data was immediately implemented into practical medicine in the fields of oncology, surgery, dermatology and dentistry, and since 1974 low level laser therapy (LLLT) is included in the standard of state medical care. For 50 years no less than 1000 books were published (monographs, collections, methodical and clinical materials), thousands of researches were carried out. Primary mechanism and patterns of interaction of LILI with acceptors within cells can be represented in the following order: absorption of photon’s energy – emergence of a local temperature gradient – release of Ca2+ from intracellular stores – stimulating Ca2+–dependent processes. Understanding of this process allowed the explanation of all known secondary effects, optimized methods and extremely increased effectiveness of LLLT. Owing to the knowledge of BMA mechanisms of LILI, numerous associated and combined LLLT techniques were developed and are widely used nowadays: locally, on the projection of internal organs, laser acupuncture, reflexology, intracavitary, transdermal and intravenous laser blood illumination, magnetic-laser therapy, laser phoresis, laser-vacuum massage, biomodulation, etc. About 400 000 laser therapeutic devices are used in Russian practical healthcare. Unique, having no analogues in the world devices, are produced – red pulsed laser diodes (wavelength 635 nm, power 5-40 W, pulse duration 100 ns, frequency 10 000 Hz) are designed specially for effective laser therapy. PMID:28652897

  5. Minimizing Superficial Thermal Injury Using Bilateral Cryogen Spray Cooling During Laser Reshaping of Composite Cartilage Grafts

    Science.gov (United States)

    Chang, Cheng-Jen; Cheng, Sally M.H.; Chiu, Lynn L.; Wong, Brian J.F.; Ting, Keen

    2014-01-01

    Composite cartilage grafts were excised from New Zealand rabbit ears. Flat composite grafts (of cartilage and overlying skin graft on both surfaces) were obtained from each ear and cut into a rectangle measuring 50 mm by 25 mm (x by y) with an average thickness of approximately 1.3 mm (z), skin included. Specimens were manually deformed with a jig and maintained in this new position during laser illumination. The composite cartilage grafts were illuminated on the concave surface with an Nd:YAG laser (1,064 nm, 3 mm spot) at 10 W, 20 W, 30 W, 40 W, 50 W. Cryogen spray cooling (CSC) was applied to both exterior (convex) and interior (concave) surfaces of the tissue to reduce thermal injury to the grafts. CSC was delivered: (1) in controlled applications (cryogen released when surface reached 40°C, and (2) receiving only laser at above wattage, no CSC [representing the control group]. The specimens were maintained in a deformation for 15 minutes after illumination and serially examined for 14 days. The control group with no CSC caused injury to all specimens, ranging from minor to full thickness epidermal thermal injury. Although most levels of laser and CSC yielded a high degree of reshaping over an acute time period, after 14 days specimens exposed to 30 W, 40 W, 50 W retained shape better than those treated at 10 W and 20 W. The specimens exposed to 50 W with controlled CSC retained its new shape to the highest degree over all others, and thermal injury was minimal. In conclusion, combinations of laser and CSC parameters were effective and practical for the reshaping of composite cartilage grafts. Lasers Surg. PMID:18727025

  6. Infrared Laser Therapy using IR absorption of biomolecules

    Energy Technology Data Exchange (ETDEWEB)

    Awazu, K; Ishii, K; Hazama, H, E-mail: awazu@see.eng.osaka-u.ac.jp [Medical Beam Physics Lab., Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871 (Japan)

    2011-02-01

    Since numerous characteristic absorption lines caused by molecular vibration exist in the mid-infrared (MIR) wavelength region, selective excitation or selective dissociation of molecules is possible by tuning the laser wavelength to the characteristic absorption lines of target molecules. By applying this feature to the medical fields, less-invasive treatment and non-destructive diagnosis with absorption spectroscopy are possible using tunable MIR lasers. A high-energy nanosecond pulsed MIR tunable laser was obtained with difference-frequency generation (DFG) between a Nd:YAG and a tunable Cr:forsterite lasers. The MIR-DFG laser was tunable in a wavelength range of 5.5-10 {mu}m and generated a laser pulses with an energy of up to 1.4 mJ, a pulse width of 5 ns, and a pulse repetition rate of 10 Hz. Selective removal of atherosclerotic lesion was successfully demonstrated with the MIR-DFG laser tuned at a wavelength of 5.75 {mu}m, which corresponds to the characteristic absorption of the ester bond in cholesterol esters in the atherosclerotic lesions. We have developed a non-destructive diagnostic probe with an attenuated total reflection (ATR) prism and two hollow optical fibres. An absorption spectrum of cholesterol was measured with the ATR probe by scanning the wavelength of the MIR-DFG laser, and the spectrum was in good agreement with that measured with a commercial Fourier transform infrared spectrometer.

  7. Low-level laser efficiency in the therapy of chronic gingivitis in children

    Directory of Open Access Journals (Sweden)

    Igić Marija

    2008-01-01

    Full Text Available Background/Aim. Gingivitis is a frequent phenomenon in children considered to be a risk factor for the occurrence and progression of paradontal tissue disease. So, it is necessary not only to identify inflammation, but also to react in due time and adequately in order to avoid further disease spread and the beginning of periodontitis. The aim of this study was to determine the efficiency of a low-level laser application in the therapy of chronic gingivitis in children. Methods. The study a included hundred of children with permanent dentition suffering from chronic gingivitis. All the examinees were divided into two groups: group I - 50 examinees with chronic gingivitis, who underwent the basic therapy; group II - 50 examinees with chronic gingivitis, who underwent the basic therapy and also a therapy with a low-level laser. Evaluation of the condition of oral hygiene, the health of gingiva and periodontium were done using appropriate index before and after the therapy. Results. For the plaque index (PI following results were obtained: in the group I PI = 1.94, and in the group II PI = 1.82. After the therapy in both groups PI was 0. In the group I sulcus plaque index (SPI was 2.02 before the therapy and 0.32 after the therapy. In the group II SPI was 1.90 before the therapy, and 0.08 after the therapy. In the group I Community Periodontal Index of Treatment Needs (CPITN was 1.66 before the therapy, and 0.32 after the therapy, and in the group II CPITN was 1.60 before the therapy, and 0.08 after the therapy. Conclusion. Chronic gingivitis in children can be successfully cured by the basic treatment. The use of a low-level laser can significantly improve this effect.

  8. MODELING OF THE THERMAL BEHAVIOR OF METALS DURING WELDING LASER USING BEAM

    Directory of Open Access Journals (Sweden)

    S. Lemkeddem

    2015-07-01

    Full Text Available The laser welding provides a very high energy density, this allows the use of welds narrow, deep and at high speeds. Because of its advantages over other joining processes, laser welding is a process of manufacturing the most important. In order to model the thermal behavior, we must study the different phenomena that may be involved in the operation. The temperature distribution in the workpiece can be determined from the heat equation which expresses the energy balance. This is a parabolic differential equation and for resolution we applied the finite difference method using the implicit scheme.

  9. THE EFFECT OF LASER GLAZING PROCESS ON MICROSTRUCTURE OF PLASMA SPRAYED THERMAL BARRIER COATINGS

    Directory of Open Access Journals (Sweden)

    Seyid Fehmi DİLTEMİZ

    2011-12-01

    Full Text Available Thermal barrier coatings (TBCs are widely used by aero and land based gas turbines to protect hot section parts from oxidation and reducing component temperature thereby increase life. TBCs aregenerally a combination of multiple layers of coating (usually two with each layer having a specific function [Aktaa et al., 2005]. In this study air plasma sprayed TBCs were deposited on 304 stainlesssteel substrates then ceramic surfaces were glazed using Nd-YAG laser. Both glazed and as-coated samples were subjected to metallographic examination to investigate microstructural changes inglazed ceramic layer. Laser glazing provides a remelting and subsequent solidification of the surface, resulting on new top layer microstructure.

  10. Direct laser writing of polymeric nanostructures via optically induced local thermal effect

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Quang Cong [Laboratoire de Photonique Quantique et Moléculaire, UMR 8537, École Normale Supérieure de Cachan, CentraleSupélec, CNRS, Université Paris-Saclay, 61 avenue du Président Wilson, 94235 Cachan (France); Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, 10000 Hanoi (Viet Nam); Nguyen, Dam Thuy Trang; Do, Minh Thanh; Luong, Mai Hoang; Journet, Bernard; Ledoux-Rak, Isabelle; Lai, Ngoc Diep, E-mail: nlai@lpqm.ens-cachan.fr [Laboratoire de Photonique Quantique et Moléculaire, UMR 8537, École Normale Supérieure de Cachan, CentraleSupélec, CNRS, Université Paris-Saclay, 61 avenue du Président Wilson, 94235 Cachan (France)

    2016-05-02

    We demonstrate the fabrication of desired structures with feature size below the diffraction limit by use of a positive photoresist. The direct laser writing technique employing a continuous-wave laser was used to optically induce a local thermal effect in a positive photoresist, which then allowed the formation of solid nanostructures. This technique enabled us to realize multi-dimensional sub-microstructures by use of a positive photoresist, with a feature size down to 57 nm. This mechanism acting on positive photoresists opens a simple and low-cost way for nanofabrication.

  11. Thermal and mechanical response of steel sheets welded by laser process: Preanalysis made by ABAQUS code

    Energy Technology Data Exchange (ETDEWEB)

    Carmignani, B.; Daneri, A.; Giambuzzi, S.; Toselli, G. [ENEA, Bologna (Italy). Centro Ricerche Energia `E. Clementel` - Area Energetica

    1994-11-01

    In this work, the conclusive report on the activity, developed in the frame of the european project EUREKA-FASP (EU353), concerning the numerical simulation of the thermal and mechanical response of steel sheets, welded by a laser welding process, is presented. This type of welding process is of interest in the shipyard field. ABAQUS code, in its implicit version, has been used. Besides the description of the studies concerning more directly the laser welding, simulations of traditional welding processes, executed in order to single out particular aspects and calculation strategies to be utilized for the simulation of the process object of the study made, are presented and discussed.

  12. Laser Produced Ions as an Injection Beam for Cancer Therapy Facility

    CERN Document Server

    Noda, A; Iwashita, Y; Nakamura, S; Sakabe, S; Shimizu, S; Shirai, T; Tongu, H

    2004-01-01

    Ion production from a solid target by a high-power short pulse laser has been investigated to replace the injector linac of the synchrotron dedicated for cancer therapy. As the high power laser, the laser with the peak power of 100 TW and minimum pulse duration of 20 fs which has been developed at JAERI Kansai Research Establishment, is assumed. Laser produced ions with 100% energy spread is energy selected within ±5% and then phase rotated with use of the RF electric field synchronized to the pulse laser, which further reduces the energy spread to ±1%. The scheme of the phase rotation is presented together with the experimental results of laser production from the thin foil target.

  13. Experimental basis of laser therapy in pharynx pathology

    Science.gov (United States)

    Toropova, Lyudmila A.; Fedyukovich, Lyudmila V.; Egorova, Alla B.

    1998-07-01

    Membrane-damaging action of laser irradiation comparing with membranotoxic activity of model xenobiotics (Novocain and Acrylamide) has been evaluated in our experiments using Rosette-Forming Ability test (RFA) on rat blood lymphocytes, thymocytes, splenocytes for the assessment of membrane- mediated and receptor-mediated immune cells interactions. Infra-red laser irradiation (80 and 1500 Hz, 0.89 mkM) in vivo induced 2-fold increase of lymphocytes capable to form specific rosettes with xenogenous erythrocytes. T-lymphocytes were greatly sensitive to the laser influence. Acute laser exposure (128 sec) induced changes similar to Novocain action (1/2 LD50). Five-fold increase of the laser exposure time (especially for low frequency regime) resulted in more prominent changes in intercellular communication which were found to be similar to the action of Acrylamide (1/2 LD50). B-lymphocytes and splenocytes have been assumed as target cells for the action of laser with the frequency of 1500 Hz. Course application of IR or He-Ne laser induced decrease of RFA for all immune cells tested, and for blood lymphocytes, respectively. Thus, laser-induced changes in immune cells interaction may be connected with reversible injury of cell surface membrane followed by the dysregulation of cellular communication. Based on experimental data, the optimal regime of IR laserotherapy (0.89 and 0.63 micrometer) was chosen for the treatment of 200 patients with chronic decompensated tonsillitis. Efficiency of laser application was confirmed by cytological analysis of lacunes, laserodopplerofluometria, vegetative nervous system evaluation etc. and was found to be dependent on membranotropic activity of laser irradiation.

  14. Comparison of subthreshold diode laser micropulse therapy versus conventional photocoagulation laser therapy as primary treatment of diabetic macular edema

    OpenAIRE

    Farhad Fazel; Majid Bagheri; Khodayar Golabchi; Hamidreza Jahanbani Ardakani

    2016-01-01

    Purpose: The aim of the present study was to investigate the effect of subthreshold diode laser micropulse (SDM) in comparison with conventional laser photocoagulation in the treatment of the diabetic macular edema (DME). Methods: Sixty-eight eyes from 68 patients with clinically significant DME were divided randomly into two equal groups. In the first group, SDM photocoagulation was employed, while conventional laser photocoagulation was performed on the eyes of the second group. Central ...

  15. Numerical Simulation of Transient Thermal Stress Field for Laser Metal Deposition Shaping

    Institute of Scientific and Technical Information of China (English)

    LONG Risheng; LIU Weijun

    2006-01-01

    To decrease thermal stress during laser metal deposition shaping (LMDS) process, it is of great importance to learn the transient thermal stress distribution regularities. Based on the "element life and death" technique of finite element analysis (FEA), a three-dimensional multi-track and multi-layer numerical simulation model for LMDS is developed with ANSYS parametric design language (APDL) for the first time, in which long-edge parallel reciprocating scanning paths is introduced. Through the model, detailed simulations of thermal stress during whole metal cladding process are conducted, the generation and distribution regularities of thermal stress are also discussed in detail. Using the same process parameters, the simulation results show good agreement with the features of samples which fabricated by LMDS.

  16. Numerical analysis of thermal distortion of the mirror in space-to-ground laser communication links

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-feng; ZHANG Bai-lei; LIN Mi; QI Li-mei

    2005-01-01

    The thermal distortion of an optical reflector surface due to the changing sunlight in a space environment will cause shift and spreading of its reflected focus and thereby influence the performance of space-to-ground laser communication links. Based on the characteristics of a low orbit satellite, the normal shift of a plan mirror caused by thermal distortion is analyzed with the software of the ANSYS of finite element analysis. A general expression of the transmitted beam from a distorted reflector surface and a counting formula for the shifts of the focus center before and after thermal distortion are deduced. The result of simulation shows that the magnitude order of the normal shift of the antenna mirror surface can be as high as tens of μrad.The worse the mirror thermal distortion is, the larger the shift of the received focus center is. And the change of the shifts does not obey a linear rule.

  17. Optical and thermal simulations of noninvasive laser coagulation of the human vas deferens

    Science.gov (United States)

    Schweinsberger, Gino R.; Cilip, Christopher M.; Trammell, Susan R.; Cherukuri, Harish; Fried, Nathaniel M.

    2011-03-01

    Successful noninvasive laser coagulation of the canine vas deferens, in vivo, has been previously reported. However, there is a significant difference between the optical properties of canine and human skin. In this study, Monte Carlo simulations of light transport through tissue and heat transfer simulations are performed to determine the feasibility of noninvasive laser vasectomy in humans. A laser wavelength of 1064 nm was chosen for deep optical penetration in tissue. Monte Carlo simulations determined the spatial distribution of absorbed photons inside the tissue layers (epidermis, dermis, and vas). The results were convolved with a 3-mm-diameter laser beam, and then used as the spatial heat source for the heat transfer model. A laser pulse duration of 500 ms and pulse rate of 1 Hz, and cryogen spray cooling were incident on the tissue for 60 s. Average laser power (5-9 W), cryogen pulse duration (60-100 ms), cryogen cooling rate (0.5-1.0 Hz), and increase in optical transmission due to optical clearing (0-50 %), were studied. After application of an optical clearing agent to increase skin transmission by 50%, an average laser power of 6 W, cryogen pulse duration of 60 ms, and cryogen cooling rate of 1 Hz resulted in vas temperatures of ~ 60°C, sufficient for thermal coagulation, while 1 mm of the skin surface (epidermis and dermis) remained at a safe temperature of ~ 45 °C. Monte Carlo and heat transfer simulations indicate that it is possible to noninvasively thermally coagulate the human vas without adverse effects (e.g. scrotal skin burns), if an optical clearing agent is applied to the skin prior to the procedure.

  18. Thermal therapy in urologic systems: a comparison of arrhenius and thermal isoeffective dose models in predicting hyperthermic injury.

    Science.gov (United States)

    He, Xiaoming; Bhowmick, Sankha; Bischof, John C

    2009-07-01

    The Arrhenius and thermal isoeffective dose (TID) models are the two most commonly used models for predicting hyperthermic injury. The TID model is essentially derived from the Arrhenius model, but due to a variety of assumptions and simplifications now leads to different predictions, particularly at temperatures higher than 50 degrees C. In the present study, the two models are compared and their appropriateness tested for predicting hyperthermic injury in both the traditional hyperthermia (usually, 43-50 degrees C) and thermal surgery (or thermal therapy/thermal ablation, usually, >50 degrees C) regime. The kinetic parameters of thermal injury in both models were obtained from the literature (or literature data), tabulated, and analyzed for various prostate and kidney systems. It was found that the kinetic parameters vary widely, and were particularly dependent on the cell or tissue type, injury assay used, and the time when the injury assessment was performed. In order to compare the capability of the two models for thermal injury prediction, thermal thresholds for complete killing (i.e., 99% cell or tissue injury) were predicted using the models in two important urologic systems, viz., the benign prostatic hyperplasia tissue and the normal porcine kidney tissue. The predictions of the two models matched well at temperatures below 50 degrees C. At higher temperatures, however, the thermal thresholds predicted using the TID model with a constant R value of 0.5, the value commonly used in the traditional hyperthermia literature, are much lower than those predicted using the Arrhenius model. This suggests that traditional use of the TID model (i.e., R=0.5) is inappropriate for predicting hyperthermic injury in the thermal surgery regime (>50 degrees C). Finally, the time-temperature relationships for complete killing (i.e., 99% injury) were calculated and analyzed using the Arrhenius model for the various prostate and kidney systems.

  19. Introductory investigations of dermatologic diode laser with wavelengths 975 nm: clinical therapy of Recklinghausen disease and of hemangiomas

    Science.gov (United States)

    Szymańczyk, J.; Cenian, W.; Piechowski, L.; Sawczak, M.; Jedrzejewska-Szczerska, M.; Cenian, A.

    2016-12-01

    The newly developed pulsed/cw dermatological laser (with wavelengths 975 nm) is applied for therapies requiring deep penetration of tissue e.g. cutaneous (dermal) neurofibroma (Recklinghausen disease) or hemangiomas. As the selected eight patients had been treated previously using pulsed a Nd:YAG laser a comparison of these therapies was possible. The results of cutaneous neurofibroma therapy using diode laser show an improvement compared with the case of Ho:YAG and Nd:YAG laser therapies - however this should be checked for a larger number of patients.

  20. Evaluation of laser therapy and routine treatment modalities in the management of myofascial pain dysfunction syndrome

    Directory of Open Access Journals (Sweden)

    Smriti B Jagdhari

    2015-01-01

    Full Text Available Objective: To evaluate the efficacy of laser as a monotherapy and in combination with exercise therapy in comparison to only exercise in the treatment of Myofascial Pain Dysfunction Syndrome (MPDS or Temporomandibular Myofascial Pain. Materials and Methods: A total of 60 patients with MPDS were included in the study and were randomly divided into three groups: exercise, laser, and the combination of both (exercise and laser. Results: Significant reduction in pain at rest and pain on movement was observed with all three types of treatment modalities. Pain reduction was more in those patients who received combination of exercise and laser therapy. Similarly, decrease in the muscle tenderness was more when combination of exercise and laser therapy was used. Conclusion: The ideal therapy should be fast, cheap, and have a long-term effect. Laser (Helium Neon as monotherapy or in combination with exercise had shown promising results and can be used as an effective treatment modality for the treatment of MPDS.

  1. Ultrasound-guided interstitial Nd:YAG laser therapy of cavernous hemangiomas

    Science.gov (United States)

    Hoffmann, Peter; Offergeld, Christian F.; Huettenbrink, Karl-Bernd; Hackert, I.; Scholz, A.

    1995-05-01

    Preoperative embolization and excision used to be standard therapy amongst a wide range of other more or less successful methods for the treatment of voluminous hemangiomas. Nowadays a combination of argon, tunable dye, copper vapor and Nd:YAG laser therapy achieves better cosmetic and functional results. Due to its limited penetration depth percutaneous laser therapy can only be utilized for superficial vascular malformations. Interstitial laser therapy, as performed with the Nd:YAG laser, allows treatment of voluminous hemangiomas in their full extent. The localization of these vascular lesions is evaluated by high resolution ultrasound with a new anular array scanner which ensures the precise intraoperative placement of the laser light fiber in the target tissue. Modified new light applicators improve the interstitial thermotherapy of hemangiomas. The tip design of the scattering-dome fiber allows diffuse circumferential irradiation with larger defined coagulation volume and minimized carbonization. Continuous intraoperative sonographic monitoring lowers the risk of damaging adjacent intact anatomical structures, helps to reach all tumor areas an to estimate the effect of the applied laser light caused by changes of sonomorphology. The postoperative outcome is evaluated by B-mode sonography and the new technique of ultrasound color angiography.

  2. Numerical analysis for characterization of the gold nanorod mediated-plasmonic heating with temporary NIR laser radiation for superficial breast cancer therapy

    Science.gov (United States)

    Bae, Ji Yong; Nam, Ki-Hwan; Jeong, Chan Bae; Kim, Geon-hee; Chang, Ki Soo

    2016-09-01

    Over the last decade, plasmonic photothermal therapy (PPTT) has received significant attention as the new therapeutic strategy for the cancer therapy due to unique characteristics of the gold-nanoparticles. The characterization of the spatiotemporal heating potential for the gold nanorods (GNR) through mimicking PPTT process on the various conditions can help more quantitative approaches to treatment planning. The purpose of this study was to clearly understand the optical-thermal interactions between the laser, GNRs, and bio-tissues, and provide the information in clinical applications to implement the concept of heterogeneity, which can enable the optimization of treatment parameters for superficial breast cancer treatment.

  3. Is it possible to prevent morbidity on post cardiovascular surgery applying low level laser therapy?

    Science.gov (United States)

    Pinto, Nathali C.; Baptista, Ivany Machado d. C.; Pereira, Mara Helena C.; Serrão, Nelson F.; Pomerantzeff, Pablo M. A.; Chavantes, Maria Cristina

    2014-03-01

    Background and Objective: Complications following cardiovascular surgery incision are common in mediastinitis and wound dehiscence form, a 47% mortality rate remaining. Low Level Laser Therapy (LLLT) has been employed mainly to its effectiveness analgesic and anti-inflammatory actions, aiding the tissue repair process. The aim of this study was to evaluate infrared LLLT onto surgical incision in patients submitted to cardiovascular surgery. Materials and Methods: 40 patients were divided in two groups: Placebo Group (G1) - conventional therapy + "Laser pointer" and Laser Group (G2) - conventional therapy + Infrared Laser irradiation on surgical incision. Diode Laser was employed, C.W. mode, around the surgical wound bed, on immediate Post Operative (PO), 1st PO and 3rd PO with the following parameters: wavelength (λ): 830nm, P=35mW, E=0,75J. Results: G2 didn't present any complication and 5% of patients in G1 developed incision dehiscence and infection. On 7thPO, still a large amount of G1 patients showed pain and unquestionable inflammatory signs surrounding the surgical wound, when compared to G2. Besides, hospital stay in Laser Group was 2 times shorter than in Placebo Group (p-value=0.001). Conclusion: Infrared Laser denoted to be safe and exceptionally valuable tools in preventing morbidities on post cardiovascular surgeries.

  4. Improving the Thermal Shock Resistance of Thermal Barrier Coatings Through Formation of an In Situ YSZ/Al2O3 Composite via Laser Cladding

    Science.gov (United States)

    Soleimanipour, Zohre; Baghshahi, Saeid; Shoja-razavi, Reza

    2017-04-01

    In the present study, laser cladding of alumina on the top surface of YSZ thermal barrier coatings (TBC) was conducted via Nd:YAG pulsed laser. The thermal shock behavior of the TBC before and after laser cladding was modified by heating at 1000 °C for 15 min and quenching in cold water. Phase analysis, microstructural evaluation and elemental analysis were performed using x-ray diffractometry, scanning electron microscopy (SEM), and energy-dispersive spectroscopy. The results of thermal shock tests indicated that the failure in the conventional YSZ (not laser clad) and the laser clad coatings happened after 200 and 270 cycles, respectively. The SEM images of the samples showed that delamination and spallation occurred in both coatings as the main mechanism of failure. Formation of TGO was also observed in the fractured cross section of the samples, which is also a main reason for degradation. Thermal shock resistance in the laser clad coatings improved about 35% after cladding. The improvement is due to the presence of continuous network cracks perpendicular to the surface in the clad layer and also the thermal stability and high melting point of alumina in Al2O3/ZrO2 composite.

  5. Laser therapy for the treatment of Hailey-Hailey disease: a systematic review with focus on carbon dioxide laser resurfacing.

    Science.gov (United States)

    Falto-Aizpurua, L A; Griffith, R D; Yazdani Abyaneh, M A; Nouri, K

    2015-06-01

    Benign familial chronic pemphigus, or Hailey-Hailey disease (HHD), is a recurrent bullous dermatitis that tends to have a chronic course with frequent relapses. Long-term treatment options include surgery with skin grafting or dermabrasion. Both are highly invasive and carry significant risks and complications. More recently, 'laser-abrasion' has been described as a less invasive option with a better side-effect profile. In this article, we systematically review the safety and efficacy of carbon dioxide laser therapy as a long-term treatment option for HHD, as well as provide a review of other lasers that have been reported with this goal. A total of 23 patients who had been treated with a carbon dioxide laser were identified. After treatment, 10 patients (43%) had had no recurrence, 10 (43%) had greater than 50% improvement, 2 (8%) had less than 50% improvement and 1 (4%) patient had no improvement at all (follow-up period ranged from 4 to 144 months). Laser parameter variability was wide and adverse effects were minimal, including dyspigmentation and scarring. Reviewed evidence indicates this therapy offers a safe, effective treatment alternative for HHD with minimal risk of side-effects. Larger, well-designed studies are necessary to determine the optimal treatment parameters. © 2014 European Academy of Dermatology and Venereology.

  6. Percutaneous laser thermal angioplasty: initial clinical results with a laser probe in total peripheral artery occlusions.

    Science.gov (United States)

    Cumberland, D C; Sanborn, T A; Tayler, D I; Moore, D J; Welsh, C L; Greenfield, A J; Guben, J K; Ryan, T J

    1986-06-28

    A metal-tipped laser fibre was used during percutaneous angioplasty of femoral/popliteal or iliac artery occlusions in 56 patients. Primary success was achieved in 50 (89%) of these total occlusions, providing a channel for subsequent balloon dilatation. Before the procedure, 18 lesions had been judged untreatable by conventional angioplasty and four of the six failures were in these. Complications directly attributable to the laser probe were one case of vessel perforation and two cases of entry into vessel walls; these had no sequelae. Other acute complications were a distal thrombosis in a non-heparinised patient, requiring local streptokinase treatment, and two reocclusions and one transient peripheral embolic episode in the first 24 hours. The laser probe technique has potential for increasing the proportion of patients suitable for angioplasty.

  7. Analysis of the Influence of Thermal Effect on Z-Scan Measurements with a Nanosecond Pulse Laser

    Institute of Scientific and Technical Information of China (English)

    TIAN Jian-Guo; WANG Hao-Hua; ZHOU Wen-Yuan; LI Tao; ZHANG Chun-Ping; ZHANG Guang-Yin

    2000-01-01

    The influence of thermally induced optical nonlinearities on Z-scan measurements with a nanosecond pulse laser is investigated theoretically. The results demonstrate that thermal effect plays an important role in certain circumstance. As an example, the optical nonlinearities of CS2 with an adjustable linear absorption coefficient which is used to alter the magnitude of thermally induced optical nonlinearities are analysed, and the results show that thermal effect even makes the change of the sign of optical nonlinearities.

  8. Thermally induced mode distortion and its limit to power scaling of fiber lasers.

    Science.gov (United States)

    Ke, Wei-Wei; Wang, Xiao-Jun; Bao, Xian-Feng; Shu, Xiao-Jian

    2013-06-17

    A general model is proposed to describe thermal-induced mode distortion in the step-index fiber (SIF) high power lasers. Two normalized parameters in the model are able to determine the mode characteristic in the heated SIFs completely. Shrinking of the mode fields and excitation of the high-order modes by the thermal-optic effect are investigated. A simplified power amplification model is used to describe the output power redistribution under various guiding modes. The results suggest that fiber with large mode area is more sensitive on the thermally induced mode distortion and hence is disadvantaged in keeping the beam quality in high power operation. The model is further applied to improve the power scaling analysis of Yb-doped fiber lasers. Here the thermal effect is considered to couple with the optical damage and the stimulated Raman scattering dynamically, whereas direct constraint from the thermal lens is relaxed. The resulting maximal output power is from 67kW to 97kW, depending on power fraction of the fundamental mode.

  9. IRON OXIDE NANOPARTICLES AS THERMAL SEEDS IN MAGNETIC HYPERTHERMIA THERAPY

    OpenAIRE

    2016-01-01

    we present the short review on Magnetic nanoparticle specifically for biomedical application. This study shows the overview on magnetic material properties and its biocompatibility. Here we are discussing some results of manufacturing iron nano particle in lab and its thermal propertie srelated to hyperthermia.  Keywords- Magnetic  nanoparticle (MNP).

  10. Laser-projected photothermal thermography using thermal wave field interference for subsurface defect characterization

    Science.gov (United States)

    Thiel, Erik; Kreutzbruck, Marc; Ziegler, Mathias

    2016-09-01

    The coherent superposition of two anti-phased thermal wave fields creates a zone of destructive interference which is extremely sensitive to the presence of defects without any reference measurements. Combining a high power laser with a spatial light modulator allows modulating phase and amplitude of an illuminated surface that induces spatially and temporally controlled thermal wave fields. The position and depth of defects are reconstructed from analysis of the amplitude and phase of the resulting photothermal signal. The proposed concept is experimentally validated and supported by numerical modeling.

  11. Pulsed pump: Thermal effects in solid state lasers under super-Gaussian pulses

    Indian Academy of Sciences (India)

    H Nadgaran; M Sabaian

    2006-12-01

    Solid state laser (SSL) powers can be realistically scaled when pumped by a real, efficient and multimode pulse. In this work, a fourth-order super-Gaussian pulse was assumed as a pump for SSL's and a complete analytical expression for the thermal phase shift is given. Moreover, the focal length of thermal lens in paraxial ray approximation regime was studied. The results when applied to a Ti : sapphire crystal show an appreciable correction for abberation compared to a top-hat pulse.

  12. Thermal analysis of GaN laser diodes in a package structure

    Institute of Scientific and Technical Information of China (English)

    Feng Mei-Xin; Yang Hui; Zhang Shu-Ming; Jiang De-Sheng; Liu Jian-Ping; Wang Hui; Zeng Chang; Li Zeng-Cheng; Wang Huai-Bing; Wang Feng

    2012-01-01

    Using the finite-element method,the thermal resistances of GaN laser diode devices in a TO 56 package for both epi-up configuration and epi-down configuration are calculated.The effects of various parameters on the thermal characteristics are analysed,and the thicknesses of the A1N submount for both epi-up configuration and epi-down configuration are optimized.The obtained result provides a reference for the parameter selection of the package materials.

  13. Activatable albumin-photosensitizer nanoassemblies for triple-modal imaging and thermal-modulated photodynamic therapy of cancer.

    Science.gov (United States)

    Hu, Dehong; Sheng, Zonghai; Gao, Guanhui; Siu, Fungming; Liu, Chengbo; Wan, Qian; Gong, Ping; Zheng, Hairong; Ma, Yifan; Cai, Lintao

    2016-07-01

    Photodynamic therapy (PDT) is a noninvasive and effective approach for cancer treatment. The main bottlenecks of clinical PDT are poor selectivity of photosensitizer and inadequate oxygen supply resulting in serious side effects and low therapeutic efficiency. Herein, a thermal-modulated reactive oxygen species (ROS) strategy using activatable human serum albumin-chlorin e6 nanoassemblies (HSA-Ce6 NAs) for promoting PDT against cancer is developed. Through intermolecular disulfide bond crosslinking and hydrophobic interaction, Ce6 photosensitizer is effectively loaded into the HSA NAs, and the obtained HSA-Ce6 NAs exhibit excellent reduction response, as well as enhanced tumor accumulation and retention. By the precision control of the overall body temperature instead of local tumor temperature increasing from 37 °C to 43 °C, the photosensitization reaction rate of HSA-Ce6 NAs increases 20%, and the oxygen saturation of tumor tissue raise 52%, significantly enhancing the generation of ROS for promoting PDT. Meanwhile, the intrinsic fluorescence and photoacoustic properties, and the chelating characteristic of porphyrin ring can endow the HSA-Ce6 NAs with fluorescence, photoacoustic and magnetic resonance triple-modal imaging functions. Upon irradiation of low-energy near-infrared laser, the tumors are completely suppressed without tumor recurrence and therapy-induced side effects. The robust thermal-modulated ROS strategy combined with albumin-based activatable nanophotosensitizer is highly potential for multi-modal imaging-guided PDT and clinical translation.

  14. Enhanced 5-aminolevulinic acid-gold nanoparticle conjugate-based photodynamic therapy using pulse laser

    Science.gov (United States)

    Xu, Hao; Yao, Cuiping; Wang, Jing; Chang, Zhennan; Zhang, Zhenxi

    2016-02-01

    The low bioavailability is a crucial limitation for the application of 5-aminolevulinic acid (ALA) in theranostics. In this research, 5-aminolevulinic acid and gold nanoparticle conjugates (ALA-GNPs) were synthesized to improve the bioavailability of ALA and to investigate the impact of ALA photodynamic therapy (ALA-PDT) in Hela cells. A 532 nm pulse laser and light-emitting diode (central wavelengths 502 nm) were jointly used as light sources in PDT research. The results show a 532 nm pulse laser can control ALA release from ALA-GNPs by adjusting the pulse laser dose. This laser control release may be attributed to the heat generation from GNPs under pulse laser irradiation, which indicates accurately adjusting the pulse laser dose to control the drug release in the cell interior can be considered as a new cellular surgery modality. Furthermore, the PDT results in Hela cells indicate the enhancement of ALA release by pulse laser before PDT can promote the efficacy of cell eradication in the light-emitting diode PDT (LED-PDT). This laser mediated drug release system can provide a new online therapy approach in PDT and it can be utilized in the optical monitor technologies based individual theranostics.

  15. Using Pre-Exercise Photobiomodulation Therapy Combining Super-Pulsed Lasers and Light-Emitting Diodes to Improve Performance in Progressive Cardiopulmonary Exercise Tests

    National Research Council Canada - National Science Library

    Miranda, Eduardo Foschini; Vanin, Adriane Aver; Tomazoni, Shaiane Silva; Grandinetti, Vanessa dos Santos; de Paiva, Paulo Roberto Vicente; Machado, Caroline dos Santos Monteiro; Monteiro, Kadma Karênina Damasceno Soares; Casalechi, Heliodora Leão; de Tarso, Paulo; de Carvalho, Camillo; Leal-Junior, Ernesto Cesar Pinto

    2016-01-01

    ...) combining superpulsed lasers (low-level laser therapy) and light-emitting diodes (LEDs) on muscle performance during a progressive cardiopulmonary treadmill exercise test. Crossover study. Laboratory...

  16. Thermoelectric and thermal properties of GaAlAs Peltier-cooled laser diodes

    Energy Technology Data Exchange (ETDEWEB)

    Hava, S.; Sequeira, H.B.; Hunsperger, R.G.

    1985-09-01

    Analyses of heat spreading, temperature distribution, and resultant cooling effects in a monolithically Peltier-cooled laser (MPCL) structure are presented. The analyses were obtained by using Laplace's equation and were made under steady-state conditions, assuming constant thermal conductivity. In this MPCL structure a metal surface layer surrounds a heat-generating p-n laser junction. It is shown that by depositing relatively thick metallic cooling plates a 15% temperature reduction and 25% thermal spreading can be achieved. This heat spreading due to the passive cooling is added to the cooling obtained when the Peltier cooler is operated. Experimental measurements of the effect of Peltier cooling reveal a 6.8 /sup 0/C reduction in junction temperature corresponding to a wavelength shift of as much as 20 A.

  17. Spectral analysis of laser-Doppler perfusion signal measured during thermal test.

    Science.gov (United States)

    Maniewski, R; Leger, P; Lewandowski, P; Liebert, A; Bendayan, P; Boccalon, H; Bajorski, L; Möller, K O

    1999-01-01

    The method of spectral analysis of laser-Doppler perfusion signal measured during thermal test is proposed. During three 20 min phases with 40, 5, and 40 degrees C of thermal test laser-Doppler perfusion signal was recorded. For each signal phase frequency spectra were calculated using the FFT method. Quantitative parameter Spectral Factor for results evaluation was proposed. In total 94 patients were measured: 69 with Raynaud's phenomenon and 25 normal subjects. Additionally in 18 Raynaud's patients the influence of Nifedipine was studied. Results suggest that proposed parameter is able to differentiate between Raynaud's patients and normal subjects and that is useful for evaluation of Nifedipine effectiveness. However, further studies are needed to improve the method to differentiate between primary and secondary Raynaud's patients.

  18. Ion intensity and thermal proton transfer in ultraviolet matrix-assisted laser desorption/ionization.

    Science.gov (United States)

    Lu, I-Chung; Lee, Chuping; Chen, Hui-Yuan; Lin, Hou-Yu; Hung, Sheng-Wei; Dyakov, Yuri A; Hsu, Kuo-Tung; Liao, Chih-Yu; Lee, Yin-Yu; Tseng, Chien-Ming; Lee, Yuan-Tseh; Ni, Chi-Kung

    2014-04-17

    The ionization mechanism of ultraviolet matrix-assisted laser desorption/ionization (UV-MALDI) was investigated by measuring the total cation intensity (not including sodiated and potasiated ions) as a function of analyte concentration (arginine, histidine, and glycine) in a matrix of 2,4,6-trihydroxyacetophenone (THAP). The total ion intensity increased up to 55 times near the laser fluence threshold as the arginine concentration increased from 0% to 1%. The increases were small for histidine, and a minimal increase occurred for glycine. Time-resolved fluorescence intensity was employed to investigate how analytes affected the energy pooling of the matrix. No detectable energy pooling was observed for pure THAP and THAP/analyte mixtures. The results can be described by using a thermal proton transfer model, which suggested that thermally induced proton transfer is crucial in the primary ion generation in UV-MALDI.

  19. Helium Neon laser therapy for post mastectomy lymphedema and ...

    African Journals Online (AJOL)

    Mohamed M. Khalaf

    2012-12-08

    Dec 8, 2012 ... musculoskeletal disorder, wound healing problem, scar and pain). Laser was ..... growth factors (VEGF) by smooth muscle cell fibroblasts and stimulation ... plays a key role in the control mechanisms for arteriolar con- striction.

  20. Gold nanoshell/polysaccharide nanofilm for controlled laser-assisted tissue thermal ablation.

    Science.gov (United States)

    Redolfi Riva, Eugenio; Desii, Andrea; Sinibaldi, Edoardo; Ciofani, Gianni; Piazza, Vincenzo; Mazzolai, Barbara; Mattoli, Virgilio

    2014-06-24

    We report on the fabrication and characterization of a freestanding ultrathin, mucoadhesive gold nanoshell/polysaccharide multilayer nanocomposite (thermonanofilm, TNF), that can be used for controlled photothermal ablation of tissues through irradiation with near-infrared radiation (NIR) laser. The aim of this work is to provide a new strategy to precisely control particle concentration during photothermalization of cancerous lesions, since unpredictable and aspecific biodistributions still remains the central issue of inorganic nanoparticle-assisted photothermal ablation. Gold nanoshell encapsulation in polysaccharide matrix is achieved by drop casting deposition method combined with spin-assisted layer-by-layer (LbL) assembly. Submicrometric thickness of films ensures tissue adhesion. Basic laser-induced heating functionality has been demonstrated by in vitro TNF-mediated thermal ablation of human neuroblastoma cancer cells, evidenced by irreversible damage to cell membranes and nuclei. Ex vivo localized vaporization and carbonization of animal muscular tissue is also demonstrated by applying TNF onto tissue surface. Thermal distribution in the tissue reaches a steady state in a few seconds, with significant increases in temperature (ΔT > 50) occurring across an 1 mm span, ensuring control of local photothermalization and providing more safety and predictability with respect to traditional laser surgery. A steady-state model of tissue thermalization mediated by TNFs is also introduced, predicting the temperature distribution being known the absorbance of TNFs, the laser power, and the tissue thermal conductivity, thus providing useful guidelines in the development of TNFs. Thermonanofilms can find applications for local photothermal treatment of cancerous lesions and wherever high precision and control of heat treatment is required.

  1. Thermal radiation of laser heated niobium clusters Nb(+)(N), 8 ⩽ N ⩽ 22.

    Science.gov (United States)

    Hansen, Klavs; Li, Yejun; Kaydashev, Vladimir; Janssens, Ewald

    2014-07-14

    The thermal radiation from small, laser heated, positively charged niobium clusters has been measured. The emitted power was determined by the quenching effect on the metastable decay, employing two different experimental protocols. The radiative power decreases slightly with cluster size and shows no strong size-to-size variations. The magnitude is 40-50 keV/s at the timescale of several microseconds, which is the measured crossover time from evaporative to radiative cooling.

  2. Laser therapy in the management of dental and oro-facial trauma

    Science.gov (United States)

    Darbar, Arun A.

    2007-02-01

    This is a clinical presentation demonstrating the efficacy of laser therapy in the treatment of patients presenting with trauma to both the hard and soft tissue in the orofacial region. The use of laser therapy aids the management of these cases where the patients often present with anxiety and a low pain threshold. The outcomes in these cases indicate good patient acceptance of the treatment, enhanced repair and tissue response suggesting that this form of treatment can be indicated for these patients. A combination of hard and soft lasers are used for the comprehensive dental management and treatment of these cases. The lasers used are a 810nm diode and an Er.CrYSGG.

  3. Thermally-Reconfigurable Quantum Photonic Circuits at Telecom Wavelength by Femtosecond Laser Micromachining

    CERN Document Server

    Flamini, Fulvio; Rab, Adil S; Spagnolo, Nicolò; D'Ambrosio, Vincenzo; Mataloni, Paolo; Sciarrino, Fabio; Zandrini, Tommaso; Crespi, Andrea; Ramponi, Roberta; Osellame, Roberto

    2015-01-01

    The importance of integrated quantum photonics in the telecom band resides on the possibility of interfacing with the optical network infrastructure developed for classical communications. In this framework, femtosecond laser written integrated photonic circuits, already assessed for quantum information experiments in the 800 nm wavelength range, have great potentials. In fact these circuits, written in glass, can be perfectly mode-matched at telecom wavelength to the in/out coupling fibers, which is a key requirement for a low-loss processing node in future quantum optical networks. In addition, for several applications quantum photonic devices will also need to be dynamically reconfigurable. Here we experimentally demonstrate the high performance of femtosecond laser written photonic circuits for quantum experiments in the telecom band and we show the use of thermal shifters, also fabricated by the same femtosecond laser, to accurately tune them. State-of-the-art manipulation of single and two-photon states...

  4. Study of laser megajoule calorimeter's thermal behaviour for energy measurement uncertainty optimisation.

    Science.gov (United States)

    Crespy, Charles; Villate, Denis; Lobios, Olivier

    2013-01-01

    For laser megajoule (LMJ) facility, an accurate procedure for laser pulse energy measurement is a crucial requirement. In this study, the influence of measurement procedure on LMJ calorimeter uncertainty is experimentally and numerically investigated. To this end, a 3D thermal model is developed and two experimental techniques are implemented. The metrological characteristics of both techniques are presented. As a first step, the model is validated by comparing numerical and experimental results. Then, the influence of a large number of parameters considered as likely uncertainty sources on calorimeter response is investigated: wavelength, pulse duration, ambient temperature, laser beam diameter.... The post processing technique procedure is also examined. The paper provides some of the parameters required to allow a robust and efficient calibration procedure to be produced.

  5. Investigation on surface figuration and microstructure of laser glazed nanostructure zirconia thermal barrier coatings

    Institute of Scientific and Technical Information of China (English)

    HUANG Binghua; WANG Hongying; HAO Yunfei; TANG Weijie

    2009-01-01

    CO2 continuous wave laser beam had been applied to the laser glazing of plasma sprayed nanostructure zirconia thermal barrier coatings. The effects of luser glazing processing parameters on the surface figuration and microstructure change had been carried out, the microstructure and phase composition of the coatings had been evaluated by the scanning electron microscope (SEM) and the X-ray diffraction (XRD). SEM observation indicates that the microstructure of the as-glazed coating could be altered from single columnar structure to a combination of the columnar grain and fine equiaxed grain with the different laser glazing conditions. XRD analysis illustrates that the predominance phase of the as-glazed coating is the metastable tetragonal phase, and the glazed coating with the single columnar structure has shown the clear orientation in (220) and (400) peaks while the other coatings do not show that.

  6. Thermal analysis of thin multi-layer metal films during femtosecond laser heating

    Science.gov (United States)

    Karakas, A.; Tunc, M.; Camdali, Ü.

    2010-12-01

    Multi-layer metals films are widely used in modern engineering applications such as gold-coated metal mirrors used in high power laser systems. A transient heat flux model is derived to analyze multi-layer metal films under laser heating. The two separate system composed of electrons and the lattice is considered to take into account the electron-lattice interaction. The present model predicted the effects of underlying chromium's thermal properties on temperature rise of the top gold layer. The effects of two adjacent and different metals with different electron-lattice coupling factors are analyzed for the heating mechanism of different lattices. The derived transient model combined with the two different conservation equations for the lattice and electrons are applied for the ultra short-pulse laser heating of a multi-layer film composed of gold and chromium.

  7. Laser High-Cycle Thermal Fatigue of Pulse Detonation Engine Combustor Materials Tested

    Science.gov (United States)

    Zhu, Dong-Ming; Fox, Dennis S.; Miller, Robert A.

    2001-01-01

    Pulse detonation engines (PDE's) have received increasing attention for future aerospace propulsion applications. Because the PDE is designed for a high-frequency, intermittent detonation combustion process, extremely high gas temperatures and pressures can be realized under the nearly constant-volume combustion environment. The PDE's can potentially achieve higher thermodynamic cycle efficiency and thrust density in comparison to traditional constant-pressure combustion gas turbine engines (ref. 1). However, the development of these engines requires robust design of the engine components that must endure harsh detonation environments. In particular, the detonation combustor chamber, which is designed to sustain and confine the detonation combustion process, will experience high pressure and temperature pulses with very short durations (refs. 2 and 3). Therefore, it is of great importance to evaluate PDE combustor materials and components under simulated engine temperatures and stress conditions in the laboratory. In this study, a high-cycle thermal fatigue test rig was established at the NASA Glenn Research Center using a 1.5-kW CO2 laser. The high-power laser, operating in the pulsed mode, can be controlled at various pulse energy levels and waveform distributions. The enhanced laser pulses can be used to mimic the time-dependent temperature and pressure waves encountered in a pulsed detonation engine. Under the enhanced laser pulse condition, a maximum 7.5-kW peak power with a duration of approximately 0.1 to 0.2 msec (a spike) can be achieved, followed by a plateau region that has about one-fifth of the maximum power level with several milliseconds duration. The laser thermal fatigue rig has also been developed to adopt flat and rotating tubular specimen configurations for the simulated engine tests. More sophisticated laser optic systems can be used to simulate the spatial distributions of the temperature and shock waves in the engine. Pulse laser high

  8. Cancer therapy using non-thermal atmospheric pressure plasma with ultra-high electron density

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Hiromasa [Institute of Innovation for Future Society, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Center for Advanced Medicine and Clinical Research, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Mizuno, Masaaki [Center for Advanced Medicine and Clinical Research, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Toyokuni, Shinya [Department of Pathology and Biological Responses, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Maruyama, Shoichi [Department of Nephrology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Kodera, Yasuhiro [Department of Gastroenterological Surgery (Surgery II), Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Terasaki, Hiroko [Department of Ophthalmology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Adachi, Tetsuo [Laboratory of Clinical Pharmaceutics, Gifu Pharmaceutical University, 501-1196 Gifu (Japan); Kato, Masashi [Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Kikkawa, Fumitaka [Department of Obstetrics and Gynecology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Hori, Masaru [Institute of Innovation for Future Society, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2015-12-15

    Cancer therapy using non-thermal atmospheric pressure plasma is a big challenge in plasma medicine. Reactive species generated from plasma are key factors for treating cancer cells, and thus, non-thermal atmospheric pressure plasma with high electron density has been developed and applied for cancer treatment. Various cancer cell lines have been treated with plasma, and non-thermal atmospheric plasma clearly has anti-tumor effects. Recent innovative studies suggest that plasma can both directly and indirectly affect cells and tissues, and this observation has widened the range of applications. Thus, cancer therapy using non-thermal atmospheric pressure plasma is promising. Animal experiments and understanding the mode of action are essential for clinical application in the future. A new academic field that combines plasma science, the biology of free radicals, and systems biology will be established.

  9. Cancer therapy using non-thermal atmospheric pressure plasma with ultra-high electron density

    Science.gov (United States)

    Tanaka, Hiromasa; Mizuno, Masaaki; Toyokuni, Shinya; Maruyama, Shoichi; Kodera, Yasuhiro; Terasaki, Hiroko; Adachi, Tetsuo; Kato, Masashi; Kikkawa, Fumitaka; Hori, Masaru

    2015-12-01

    Cancer therapy using non-thermal atmospheric pressure plasma is a big challenge in plasma medicine. Reactive species generated from plasma are key factors for treating cancer cells, and thus, non-thermal atmospheric pressure plasma with high electron density has been developed and applied for cancer treatment. Various cancer cell lines have been treated with plasma, and non-thermal atmospheric plasma clearly has anti-tumor effects. Recent innovative studies suggest that plasma can both directly and indirectly affect cells and tissues, and this observation has widened the range of applications. Thus, cancer therapy using non-thermal atmospheric pressure plasma is promising. Animal experiments and understanding the mode of action are essential for clinical application in the future. A new academic field that combines plasma science, the biology of free radicals, and systems biology will be established.

  10. Transient Thermal Analysis of Ridge Waveguide InAsP/InGaAsP MQW Lasers Operating in Pulse Driving Conditions

    Institute of Scientific and Technical Information of China (English)

    HE You-jun; ZHANG Yong-gang; LI Ai-zhen

    2003-01-01

    The transient thermal characteristics of the ridge waveguide InAsP/InGaAsP MQW lasers, especially in various pulse driving conditions,have been simulated by using FEM. The temperature at the active core of the laser versus the time has been calculated as well as pulse width dependence of the apparent thermal resistance.The results show that the thermal characteristics of the lasers are related to both the thermal conductivity and the specific heat of the materials.

  11. A Flexible 360-Degree Thermal Sound Source Based on Laser Induced Graphene

    Directory of Open Access Journals (Sweden)

    Lu-Qi Tao

    2016-06-01

    Full Text Available A flexible sound source is essential in a whole flexible system. It’s hard to integrate a conventional sound source based on a piezoelectric part into a whole flexible system. Moreover, the sound pressure from the back side of a sound source is usually weaker than that from the front side. With the help of direct laser writing (DLW technology, the fabrication of a flexible 360-degree thermal sound source becomes possible. A 650-nm low-power laser was used to reduce the graphene oxide (GO. The stripped laser induced graphene thermal sound source was then attached to the surface of a cylindrical bottle so that it could emit sound in a 360-degree direction. The sound pressure level and directivity of the sound source were tested, and the results were in good agreement with the theoretical results. Because of its 360-degree sound field, high flexibility, high efficiency, low cost, and good reliability, the 360-degree thermal acoustic sound source will be widely applied in consumer electronics, multi-media systems, and ultrasonic detection and imaging.

  12. Influences of pump transitions on thermal effects of multi-kilowatt thulium-doped fiber lasers

    CERN Document Server

    Yang, Jianlong; Tang, Yulong; Xu, Jianqiu

    2015-01-01

    Thermal effects are critical constrains for developing high-power thulium-doped fiber lasers (TDFLs). In this paper, we numerically investigate the lasing and thermal characteristics of the TDFLs under different pump transitions. Our results show, the widely-used pump transition $^3H_6\\rightarrow^3H_4$, taking advantages of high-power high-efficiency laser diodes at $\\sim$0.8 $\\mu$m, may not be a superior choice for directly outputting multi-kilowatt at 2 $\\mu$m because of severe thermal problems. Meanwhile, using other pump transitions resulting 2-$\\mu$m emissions, especially the in-band pump transition $^3H_6\\rightarrow^3F_4$, will decrease the generated heat to a large extent. By optimizing the power filling factor of the gain fiber, we find a 2-$\\mu$m TDFL cladding-pumped at 1.9 $\\mu$m will lead to the laser slope efficiency close to its quantum efficiency (95\\%). The induced ultra-low quantum defect would be of great importance for power scaling. We thus propose tandem-pumped TDFLs for reducing the heat ...

  13. Mechanical, thermal and laser damage threshold analyses of II group metal complexes of thiourea

    Energy Technology Data Exchange (ETDEWEB)

    Dhanuskodi, S., E-mail: dhanus2k3@yahoo.com [School of Physics, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu (India); Sabari Girisun, T.C. [School of Physics, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu (India); Department of Physics, Bishop Heber College, Tiruchirappalli 620 017, Tamil Nadu (India); Bhagavannarayana, G. [Material Characterization Division, National Physical laboratory, New Delhi 110 012 (India); Uma, S.; Phillip, J. [Sophisticated Test and Instrumentation Center, Cochin University of Science and Technology, Cochin 682 022 (India)

    2011-04-15

    Research highlights: {yields} The role of the Group II metal ions in improving the stability is discussed. {yields} BTCC has a higher heat capacity than BTZC. {yields} Elastic stiffness is found to be higher for BTCC than BTZC. {yields} Microscopy studies confirm the damage is due to thermo-chemical ablation. {yields} BTCC has a higher laser damage threshold than BTZC. - Abstract: Single crystals of thiourea metal complexes with selected Group II metal ions, Zinc and Cadmium, have been grown by solvent evaporation technique. The crystals grown are bisthiourea zinc chloride (BTZC) and bisthiourea cadmium chloride (BTCC). Following an improved photopyroelectric technique, the thermal transport properties have been determined. It is found that BTCC has a higher heat capacity (304.09 J kg{sup -1} K{sup -1}) than BTZC (255.24 J kg{sup -1} K{sup -1}), and hence BTCC has better thermal stability. Vicker's microhardness measurements reveal that these materials have reverse indentation size effect and belong to the category of soft materials. Elastic stiffness is found to be higher for BTCC (1.57 GPa) than BTZC (0.76 GPa). The roles of the Group II metal ions in improving the mechanical and thermal stability of the metal complexes are discussed. Multi-shot laser damage studies on these materials reveal that BTCC has a higher laser damage threshold (15 GW cm{sup -2}) than BTZC (6 GW cm{sup -2}).

  14. Image-guided genomic analysis of tissue response to laser-induced thermal stress

    Science.gov (United States)

    Mackanos, Mark A.; Helms, Mike; Kalish, Flora; Contag, Christopher H.

    2011-05-01

    The cytoprotective response to thermal injury is characterized by transcriptional activation of ``heat shock proteins'' (hsp) and proinflammatory proteins. Expression of these proteins may predict cellular survival. Microarray analyses were performed to identify spatially distinct gene expression patterns responding to thermal injury. Laser injury zones were identified by expression of a transgene reporter comprised of the 70 kD hsp gene and the firefly luciferase coding sequence. Zones included the laser spot, the surrounding region where hsp70-luc expression was increased, and a region adjacent to the surrounding region. A total of 145 genes were up-regulated in the laser irradiated region, while 69 were up-regulated in the adjacent region. At 7 hours the chemokine Cxcl3 was the highest expressed gene in the laser spot (24 fold) and adjacent region (32 fold). Chemokines were the most common up-regulated genes identified. Microarray gene expression was successfully validated using qRT- polymerase chain reaction for selected genes of interest. The early response genes are likely involved in cytoprotection and initiation of the healing response. Their regulatory elements will benefit creating the next generation reporter mice and controlling expression of therapeutic proteins. The identified genes serve as drug development targets that may prevent acute tissue damage and accelerate healing.

  15. Use of laser flow visualization techniques in reactor component thermal-hydraulic studies

    Energy Technology Data Exchange (ETDEWEB)

    Oras, J.J.; Kasza, K.E.

    1984-01-01

    To properly design reactor components, an understanding of the various thermal hydraulic phenomena, i.e., thermal stratification flow channeling, recirculation regions, shear layers, etc., is necessary. In the liquid metal breeder reactor program, water is commonly used to replace sodium in experimental testing to facilitate the investigations, (i.e., reduce cost and allow fluid velocity measurement or flow pattern study). After water testing, limited sodium tests can be conducted to validate the extrapolation of the water results to sodium. This paper describes a novel laser flow visualization technique being utilized at ANL together with various examples of its use and plans for further development. A 3-watt argon-ion laser, in conjunction with a cylindrical opticallens, has been used to create a thin (approx. 1-mm) intense plane of laser light for the illuminiation of various flow tracers in precisely defined regions of interest within a test article having windows. Both fluorescing dyes tuned to the wavelength of the laser light (to maximize brightness and sharpness of flow image) and small (< 0.038-mm, 0.0015-in. dia.) opaque, nearly neutrally buoyant polystyrene spheres (to ensure that the particles trace out the fluid motion) have been used as flow tracers.

  16. Low-Level Laser Therapy (LLLT) for periodontal pockets: a review

    Science.gov (United States)

    Pribac, Valentin; Todea, Carmen; Duma, Virgil-Florin

    2016-03-01

    The applications of lasers in medicine, both in the field of diagnosis and treatment are gaining momentum. In dentistry in particular, numerous types of lasers with a wide range of characteristics are being utilized in all fields. In consequence, a lot of experience and knowledge has been gained in the last two decades in this domain; this resulted in the development of novel technologies and devices. A brief overview is made in the first part of this article on these topics. The treatment of periodontal disease with laser therapy is pointed out, as well as the photodynamic therapy which is using LLLT for the activation of the sensitizing gel that is introduced in the periodontal pockets. This paper reviews also the application of photodynamic therapy in clinical trials which have different results; a standardization of the protocol utilized for this procedure is concluded to be necessary.

  17. Preconditioning and low level laser therapy and post-treatment management in dental practice

    Science.gov (United States)

    Darbar, Arun; Darbar, Rita

    2011-03-01

    For the last decade we have been applying the principles of Low level laser therapy and have broadened the concept for practical use before and after treatment with surgical lasers. The purpose of this clinical presentation is to demonstrate how this concept has improved treatment outcomes. Cases treated in our dental practice will be demonstrated with the protocols used. A look at the science behind this concept will be examined in an effort to explain the results and to open discussion.

  18. A fundamental study on hyper-thermal neutrons for neutron capture therapy.

    Science.gov (United States)

    Sakurai, Y; Kobayashi, T; Kanda, K

    1994-12-01

    The utilization of hyper-thermal neutrons, which have an energy spectrum with a Maxwellian distribution at a higher temperature than room temperature (300 K), was studied in order to improve the thermal neutron flux distribution at depth in a living body for neutron capture therapy. Simulation calculations were carried out using a Monte Carlo code 'MCNP-V3' in order to investigate the characteristics of hyper-thermal neutrons, i.e. (i) depth dependence of the neutron energy spectrum, and (ii) depth distribution of the reaction rate in a water phantom for materials with 1/v neutron absorption. It is confirmed that hyper-thermal neutron irradiation can improve the thermal neutron flux distribution in the deeper areas in a living body compared with thermal neutron irradiation. When hyper-thermal neutrons with a 3000 K Maxwellian distribution are incident on a body, the reaction rates of 1/v materials such as 14N, 10B etc are about twice that observed for incident thermal neutrons at 300 K, at a depth of 5 cm. The limit of the treatable depth for tumours having 30 ppm 10B is expected to be about 1.5 cm greater by utilizing hyper-thermal neutrons at 3000 K compared with the incidence of thermal neutrons at 300 K.

  19. Therapy: a new nonsurgical therapy option for benign thyroid nodules?

    DEFF Research Database (Denmark)

    Hegedüs, Laszlo

    2009-01-01

    Despite the increasing implementation of iodization programs, benign nodular thyroid disease will remain a prevalent therapeutic concern for decades. recent research suggests that nonsurgical therapy, including radioactive iodine, radiofrequency thermal ablation and percutaneous laser ablation...

  20. Thermal barrier ZrO2 - Y2O3 obtained by plasma spraying method and laser melting

    OpenAIRE

    2006-01-01

    Purpose: The aim of the paper is to determine the influence of laser melting upon the selected physical properties of ZrO2 - Y2O3 ceramic coatings deposited by APS (Air Plasma Spraying) method on super-alloys which function as TBC (Thermal Barriers Coatings).Design/methodology/approach: Laser melting which helps eliminate pores and other structural defects of coatings deposited by plasma spraying method should contribute to the improvement of their density and durability as thermal barriers. ...

  1. Relativistic self-focusing of intense laser beam in thermal collisionless quantum plasma with ramped density profile

    Science.gov (United States)

    Zare, S.; Yazdani, E.; Rezaee, S.; Anvari, A.; Sadighi-Bonabi, R.

    2015-04-01

    Propagation of a Gaussian x-ray laser beam has been analyzed in collisionless thermal quantum plasma with considering a ramped density profile. In this density profile due to the increase in the plasma density, an earlier and stronger self-focusing effect is noticed where the beam width oscillates with higher frequency and less amplitude. Moreover, the effect of the density profile slope and the initial plasma density on the laser propagation has been studied. It is found that, by increasing the initial density and the ramp slope, the laser beam focuses faster with less oscillation amplitude, smaller laser spot size and more oscillations. Furthermore, a comparison is made among the laser self-focusing in thermal quantum plasma, cold quantum plasma and classical plasma. It is realized that the laser self-focusing in the quantum plasma becomes stronger in comparison with the classical regime.

  2. Evaluation of the effect of low level laser therapy toothbrush in treatment of dentin hypersensitivity.

    Science.gov (United States)

    Yaghini, Jaber; Mogharehabed, Ahmad; Safavi, Nassimeh; Mohamadi, Mehrnush; Ashtiju, Fahime

    2015-01-01

    Dentin hypersensitivity is one of the most common complications that affect patients after periodontal therapy. Recently low level laser therapy has been introduced as a new treatment modality and has produced beneficial results. The purpose of this study is to evaluate the effect of low level laser therapy toothbrushes in reduction of dentin hypersensitivity. In this pilot interventional controlled clinical trial, 40 patients suffering from dentin hypersensitivity were selected using simple randomization. Half of the patients were given laser toothbrushes and the other half was given non-laser sensodyne toothbrushes. Primary dentin hypersensitivity was recorded by visual analogue scale (VAS) score and ice spray. Then dentin hypersensitivity was measured right after the treatment as well az in the intervals of 1 month and 2 months after initiation of the study. Data were compared using Statistical Package for the Social Sciences (SPSS) software and Analysis of variance (ANOVA) paired T test. The results of this study showed that there was a significant difference in each of the two kinds of tooth brushes separately for all time intervals (P sensodyne and laser tooth brushes improve dentin hypersensitivity, although the laser toothbrush led to better results in short.

  3. Capture and Transport of Laser Accelerated Protons by Pulsed Magnetic Fields: Advancements Toward Laser-Based Proton Therapy

    Science.gov (United States)

    Burris-Mog, Trevor J.

    The interaction of intense laser light (I > 10 18 W/cm2) with a thin target foil leads to the Target Normal Sheath Acceleration mechanism (TNSA). TNSA is responsible for the generation of high current, ultra-low emittance proton beams, which may allow for the development of a compact and cost effective proton therapy system for the treatment of cancer. Before this application can be realized, control is needed over the large divergence and the 100% kinetic energy spread that are characteristic of TNSA proton beams. The work presented here demonstrates control over the divergence and energy spread using strong magnetic fields generated by a pulse power solenoid. The solenoidal field results in a parallel proton beam with a kinetic energy spread DeltaE/E = 10%. Assuming that next generation lasers will be able to operate at 10 Hz, the 10% spread in the kinetic energy along with the 23% capture efficiency of the solenoid yield enough protons per laser pulse to, for the first time, consider applications in Radiation Oncology. Current lasers can generate proton beams with kinetic energies up to 67.5 MeV, but for therapy applications, the proton kinetic energy must reach 250 MeV. Since the maximum kinetic energy Emax of the proton scales with laser light intensity as Emax ∝ I0.5, next generation lasers may very well accelerate 250 MeV protons. As the kinetic energy of the protons is increased, the magnetic field strength of the solenoid will need to increase. The scaling of the magnetic field B with the kinetic energy of the protons follows B ∝ E1/2. Therefor, the field strength of the solenoid presented in this work will need to be increased by a factor of 2.4 in order to accommodate 250 MeV protons. This scaling factor seems reasonable, even with present technology. This work not only demonstrates control over beam divergence and energy spread, it also allows for us to now perform feasibility studies to further research what a laser-based proton therapy system

  4. Low power laser therapy in treatment of bronchial asthma

    Directory of Open Access Journals (Sweden)

    Milojević Momir

    2003-01-01

    Full Text Available Introduction Modern concept of acupuncture is based on the fact there are designated locations on the surface of human body, which are related to integrative systems of an organism by means of sensory nerves, correlating and synchronizing organ functioning, depending on external and internal conditions, by means of nervous and neurohumoral regulation of metabolic and regenerative processes, including also mobilization of immunological, protective and antistress reactions. Apart from standard needle acupuncture, other methods of stimulating acupuncture points are also applied. Due to invention of low power lasers, irradiation laser acupuncture has been introduced into routine medical practice, characterized by painless and aseptic technique and outstanding clinical results. Material and methods The investigation was aimed at defining therapeutic effects of low power laser irradiation by stimulating acupuncture points or local treatment of asthma. A prospective analysis included 50 patients treated at the Institute of Pulmonary Diseases in Sremska Kamenica during 2000, 2001 and 2002. Together with conservative treatment of present disease, these patients were treated with laser stimulation of acupuncture points in duration of ten days. During treatment changes of functional respiratory parameters were recorded. Results were compared with those in the control group. The control group consisted of the same number of patients and differed from the examination group only by not using laser stimulation. Results Patients with bronchial asthma presented with significant improvement (p<0,0005 of all estimated lung function parameters just 30 minutes after laser stimulation. Improvements achieved on the third and the tenth day of treatment were significantly higher (p<0,001 to p<0,00005 in the examination group in comparison with the control group. Further investigation confirmed that improvement of measured lung function parameters was significantly

  5. Investigation of the effects of LIFT printing with a KrF-excimer laser on thermally sensitive electrically conductive adhesives

    NARCIS (Netherlands)

    Perinchery, S.M.; Smits, E.C.P.; Sridhar, A.; Albert, P.; Brand, J. van den; Mandamparambil, R.; Yakimets, I.; Schoo, H.F.M.

    2014-01-01

    Laser induced forward transfer is an emerging material deposition technology. We investigated the feasibility of this technique for printing thermally sensitive, electrically conductive adhesives with and without using an intermediate dynamic release layer. A 248nm KrF-excimer laser was used to prin

  6. Outcome of low level lasers versus ultrasonic therapy in de Quervain’s tenosynovitis

    Directory of Open Access Journals (Sweden)

    Renu Sharma

    2015-01-01

    Results: Significant improvement was seen within both groups in the following outcome measures assessed: Ritchie’s tenderness scale, grip strength and VAS. Finkelstein’s test was not significantly improved in either groups. Ultrasonographic measurement of tendon sheath diameters, the mediolateral (ML, and anteroposterior (AP diameters was not found to be significantly different in the US Th. group and the laser therapy group after treatment. On comparing both the groups, no statistically significant difference was found. However, looking at the mean values, the grip strength and VAS showed better improvement in the US Th. group as compared to the laser therapy group.

  7. Improved low-power semiconductor diode lasers for photodynamic therapy in veterinary medicine

    Science.gov (United States)

    Lee, Susanne M.; Mueller, Eduard K.; Van de Workeen, Brian C.; Mueller, Otward M.

    2001-05-01

    Cryogenically cooling semiconductor diode lasers provides higher power output, longer device lifetime, and greater monochromaticity. While these effects are well known, such improvements have not been quantified, and thus cryogenically operated semiconductor lasers have not been utilized in photodynamic therapy (PDT). We report quantification of these results from laser power meter and photospectrometer data. The emission wavelengths of these low power multiple quantum well semiconductor lasers were found to decrease and become more monochromatic with decreasing temperature. Significant power output improvements also were obtained at cryogenic temperatures. In addition, the threshold current, i.e. the current at which lasing begins, decreased with decreasing temperature. This lower threshold current combined with the increased power output produced dramatically higher device efficiencies. It is proposed that cryogenic operation of semiconductor diode lasers will reduce the number of devices needed to produce the requisite output for many veterinary and medical applications, permitting significant cost reductions.

  8. Effect of Thermal and Diffusion Processes on Formation of the Structure of Weld Metal in Laser Welding of Dissimilar Materials

    Science.gov (United States)

    Turichin, G. A.; Klimova, O. G.; Babkin, K. D.; Pevzner, Ya. B.

    2014-01-01

    The thermal and diffusion processes in laser welding of dissimilar materials are simulated. The active LaserCAD model for welding of dissimilar materials is amended. The developed model is verified for the Fe - Cu system. The microstructure of a weld of tin bronze and low-carbon steel is studied and the elements in the diffusion zone are analyzed. The computed and experimental data for laser and electron-beam welding are shown to agree well.

  9. Effect of thermal exposure on microstructure and tensile properties of laser deposited Ti60A alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ali [Engineering Research Center of Ministry of Education on Laser Direct Manufacturing for Large Metallic Components, School of Materials Science and Engineering, Beihang University, 37 Xueyuan Road, Beijing 100191 (China); Liu, Dong, E-mail: liudong.buaa@gmail.com [Engineering Research Center of Ministry of Education on Laser Direct Manufacturing for Large Metallic Components, School of Materials Science and Engineering, Beihang University, 37 Xueyuan Road, Beijing 100191 (China); Wang, Huaming [Engineering Research Center of Ministry of Education on Laser Direct Manufacturing for Large Metallic Components, School of Materials Science and Engineering, Beihang University, 37 Xueyuan Road, Beijing 100191 (China)

    2013-02-01

    A near {alpha} high-temperature titanium alloy Ti60A (Ti5.54Al3.38Sn3.34Zr0.37Mo0.46Si) was fabricated by laser melting deposition (LMD) manufacturing process. Room-temperature tensile properties before and after 600 Degree-Sign C/100 h thermal exposure were evaluated. Microstructural changes and tensile fracture characteristics were examined by OM, SEM and TEM equipped with EDX. Results indicate that {alpha} lamellae coarsening and the precipitation of incoherent silicides and coherent Ti{sub 3}Al in the alloys after thermal exposure cause the degradation of tensile properties. The silicides are confirmed to be hexagonal quasi-S{sub 2} type (TiZr{sub 0.3}){sub 6}Si{sub 3}, with a=0.71 nm and c=0.37 nm by electron diffraction analysis. Compared to wrought Ti60A alloy with coarse Widmanstatten microstructure, laser deposited Ti60A alloy with fine basket-weave microstructure exhibits slightly higher strength and ductility after thermal exposure. The effect of thermal exposure on tensile properties related to the precipitation of Ti{sub 3}Al and silicides is discussed.

  10. Laser Welded versus Resistance Spot Welded Bone Implants: Analysis of the Thermal Increase and Strength

    Science.gov (United States)

    Fornaini, Carlo; Meleti, Marco; Bonanini, Mauro; Lagori, Giuseppe; Vescovi, Paolo; Merigo, Elisabetta; Nammour, Samir

    2014-01-01

    Introduction. The first aim of this “ex vivo split mouth” study was to compare the thermal elevation during the welding process of titanium bars to titanium implants inserted in pig jaws by a thermal camera and two thermocouples. The second aim was to compare the strength of the joints by a traction test with a dynamometer. Materials and Methods. Six pigs' jaws were used and three implants were placed on each side of them for a total of 36 fixtures. Twelve bars were connected to the abutments (each bar on three implants) by using, on one side, laser welding and, on the other, resistance spot welding. Temperature variations were recorded by thermocouples and by thermal camera while the strength of the welded joint was analyzed by a traction test. Results. For increasing temperature, means were 36.83 and 37.06, standard deviations 1.234 and 1.187, and P value 0.5763 (not significant). For traction test, means were 195.5 and 159.4, standard deviations 2.00 and 2.254, and P value 0.0001 (very significant). Conclusion. Laser welding was demonstrated to be able to connect titanium implant abutments without the risk of thermal increase into the bone and with good results in terms of mechanical strength. PMID:25110731

  11. The effects of low level laser therapy on injured skeletal muscle

    Directory of Open Access Journals (Sweden)

    Ana Claudia Muniz Renno

    2014-02-01

    Full Text Available The main purpose of the present study was to investigate the effects of low-level laser therapy (LLLT used in two different fluencies on injured skeletal muscle after cryolesion by means of histopathological analysis and immunohistochemistry for COX-2. A total of sixty male Wistar rats were randomly distributed into three groups: injured animals without any treatment; 808 nm laser treated group, at 10 J/cm² and 808 nm laser treated group, at 50 J/cm². Each group was divided into two different subgroups (n=10 on days 6 and 13 post-injury. The results showed that the animals irradiated with laser at 10 J/cm² or 50 J/cm² presented the areas with cell infiltrate and pointed out to minor and mild areas with destroyed zones compared with the control group. Also, a COX-2 downregulation was noticed in the groups exposed to laser at two fluences evaluated in this study. Significant statistically differences (p<0.05 were noticed to collagen deposition in the laser treated animals, with the fluence of 50 J/cm² when compared to the other groups on day 13 post-surgery. Taken together, these results suggested that laser therapy could have positive effects on muscle repair in the rats after cryolesion.

  12. Experimental study of thermally-driven micro-pump using stepped laser

    Institute of Scientific and Technical Information of China (English)

    ZHOU Hong; HUAI Xiulan; LI Huazhi; LIU Dengying; MENG Qun

    2004-01-01

    The stepped pulse-laser is used to heat the fluid in a micro-tube with the diameter less than 1 mm, and a phase change and a directional flow of the fluid are induced. Based on many experimental observations, the mechanism of thermally-driven MEMS is studied and the technical approaches of the efficient and steady thermally-driven flow is given. The experimental results show that the hypostasis of the thermally-driven micro-pump is a kind of erratic liquid-vapor two-phase flow, and the liquid movement and the change rate of the pressure is closely related to the bubbles' behavior in the micro-tube.

  13. Study on thermal diffusivity of materials by laser photothermal reflection technique

    Institute of Scientific and Technical Information of China (English)

    Peiji Wang(王培吉); Fengjun Zhang(张奉军); Xueren Dong(董学仁); Zhong Zhang(张仲); Suhua Fan(范素华)

    2003-01-01

    A method of measuring thermal diffusivity of materials at room temperature by photothermal reflectiontechnique is described. An intensity-modulated Ar+ laser beam is used as incident light. The beam isfocused to about 1 mm diameter spot and illuminates the sample surface. HgCdTe infrared detector isused to receive photothermal signal. Using this technique, the photothermal signals are experimentallymeasured as the function of different frequencies. The thermal diffusivities can be obtained by fittingthe experimental data. On the other hand, the thermal diffusivities of one-way composite and orthogonalsymmetric arranged composites A12O3/A1 are measured in transverse, longitudinal and arbitrary directions.The results show that the diffusivity of one-way material decreases with the increase of the measurementangle; the diffusivity of orthogonally arranged material almost keeps the same when measurement anglechanges.

  14. Experimental investigation of the vibrational and thermal response of a laser spark plug

    Science.gov (United States)

    Yoder, Gregory S.

    A study was conducted in order to evaluate the external thermal and vibrational effects on the operation of a laser ignition system for internal combustion (IC) engine applications. West Virginia University (WVU) in conjunction with the National Energy Technology Laboratory (NETL) have constructed a prototype laser spark plug which has been designed to mount directly onto the head of a natural gas engine for the purpose of igniting an air/fuel (A/F) mixture in the engine's combustion chamber. To be considered as a viable replacement for the conventional electrode-based ignition system, integrity, durability and reliability must be justified. Thermal and oscillatory perturbations induced upon the ignition system are major influences that affect laser spark plug (LSP) operation and, therefore, quantifying these effects is necessary to further the advancement and development of this technology. The passively q-switched Nd:YAG laser was mounted on Bruel & Kjaer (B&K) Vibration Exciter Type 4808 Shaker in conjunction with at B&K Power Amplifier Type 2719, which was oscillated in 10 Hz intervals from 0 to 60 Hz using a sine wave to mimic natural gas engine operation. The input signal simulated the rotational velocity of the engine operating from 0 to 3600 RPM with the laser mounted in three different axial orientations. The laser assembly was wrapped with medium-temperature heat tape, outfitted with thermocouples and heated from room temperature to 140 ºF to simulate the temperatures that the LSP may experience when installed on an engine. The acceleration of the payload was varied between 50% and 100% of the oscillator's maximum allowable acceleration in each mounting orientation resulting in a total of 294 total setpoints. For each setpoint, pulse width, pulse width variation, q-switch delay, jitter and output energy were measured and recorded. Each of these dependent variables plays a critical role in multi photon ionization and precise control is necessary to limit

  15. Laser-Induced Thermal-Mechanical Damage Characteristics of Cleartran Multispectral Zinc Sulfide with Temperature-Dependent Properties

    Science.gov (United States)

    Peng, Yajing; Jiang, Yanxue; Yang, Yanqiang

    2015-01-01

    Laser-induced thermal-mechanical damage characteristics of window materials are the focus problems in laser weapon and anti-radiation reinforcement technology. Thermal-mechanical effects and damage characteristics are investigated for cleartran multispectral zinc sulfide (ZnS) thin film window materials irradiated by continuous laser using three-dimensional (3D) thermal-mechanical model. Some temperature-dependent parameters are introduced into the model. The temporal-spatial distributions of temperature and thermal stress are exhibited. The damage mechanism is analyzed. The influences of temperature effect of material parameters and laser intensity on the development of thermal stress and the damage characteristics are examined. The results show, the von Mises equivalent stress along the thickness direction is fluctuant, which originates from the transformation of principal stresses from compressive stress to tensile stress with the increase of depth from irradiated surface. The damage originates from the thermal stress but not the melting. The thermal stress is increased and the damage is accelerated by introducing the temperature effect of parameters or the increasing laser intensity.

  16. The role of radiation transport in the thermal response of semitransparent materials to localized laser heating

    Energy Technology Data Exchange (ETDEWEB)

    Colvin, Jeffrey [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Shestakov, Aleksei [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Stolken, James [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Vignes, Ryan [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2011-03-09

    Lasers are widely used to modify the internal structure of semitransparent materials for a wide variety of applications, including waveguide fabrication and laser glass damage healing. The gray diffusion approximation used in past models to describe radiation cooling is not adequate for these materials, particularly near the heated surface layer. In this paper we describe a computational model based upon solving the radiation transport equation in 1D by the Pn method with ~500 photon energy bands, and by multi-group radiationdiffusion in 2D with fourteen photon energy bands. The model accounts for the temperature-dependent absorption of infrared laser light and subsequent redistribution of the deposited heat by both radiation and conductive transport. We present representative results for fused silica irradiated with 2–12 W of 4.6 or 10.6 µm laser light for 5–10 s pulse durations in a 1 mm spot, which is small compared to the diameter and thickness of the silica slab. Furthermore, we show that, unlike the case for bulk heating, in localized infrared laser heatingradiation transport plays only a very small role in the thermal response of silica.

  17. Thermal transport in suspended silicon membranes measured by laser-induced transient gratings

    Directory of Open Access Journals (Sweden)

    A. Vega-Flick

    2016-12-01

    Full Text Available Studying thermal transport at the nanoscale poses formidable experimental challenges due both to the physics of the measurement process and to the issues of accuracy and reproducibility. The laser-induced transient thermal grating (TTG technique permits non-contact measurements on nanostructured samples without a need for metal heaters or any other extraneous structures, offering the advantage of inherently high absolute accuracy. We present a review of recent studies of thermal transport in nanoscale silicon membranes using the TTG technique. An overview of the methodology, including an analysis of measurements errors, is followed by a discussion of new findings obtained from measurements on both “solid” and nanopatterned membranes. The most important results have been a direct observation of non-diffusive phonon-mediated transport at room temperature and measurements of thickness-dependent thermal conductivity of suspended membranes across a wide thickness range, showing good agreement with first-principles-based theory assuming diffuse scattering at the boundaries. Measurements on a membrane with a periodic pattern of nanosized holes (135nm indicated fully diffusive transport and yielded thermal diffusivity values in agreement with Monte Carlo simulations. Based on the results obtained to-date, we conclude that room-temperature thermal transport in membrane-based silicon nanostructures is now reasonably well understood.

  18. Steady-state sinusoidal thermal characterization at chip level by internal infrared-laser deflection

    Energy Technology Data Exchange (ETDEWEB)

    Perpina, Xavier; Jorda, Xavier; Vellvehi, Miquel [Centre Nacional de Microelectronica (IMB-CNM-CSIC), Campus UAB, 08193 Bellaterra, Barcelona (Spain); Altet, Josep [Departament d' Enginyeria Electronica, Universitat Politecnica de Catalunya, Barcelona 08034 (Spain); Mestres, NarcIs [Institut de Ciencia dels Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193 Bellaterra, Barcelona (Spain)

    2008-08-07

    A new approach is reported for thermally characterizing microelectronic devices and integrated circuits under a steady-state sinusoidal regime by internal infrared-laser deflection (IIR-LD). It consists of extracting the amplitude and phase Bode plots of the temperature profile inside the chip (depth-resolved measurements in the frequency domain). As a consequence, not only are the IIR-LD performances significantly improved (accuracy, robustness to noise, control of boundary conditions and heat flux confinement) but also the direct temperature measurement is feasible when thin regions are inspected and thermal parameters can be easily extracted (thermal diffusivity). In order to show the efficiency of this technique, a thermal test chip (TTC) is used. The TTC is thermally excited by imposing a cosine-like voltage waveform. As a result, a vertical temperature profile inside the die is obtained depending on the heating frequency. Repeating this procedure at several frequencies, the frequency response of the chip internal temperature profile is derived. By comparing the experimental results with the model predictions, good agreement is achieved. This technique allows evaluation of the thermal behaviour at the chip level; also it could be useful for failure analysis.

  19. A comparison of temperature profile depending on skin types for laser hair removal therapy.

    Science.gov (United States)

    Kim, Tae-Hoon; Lee, Gwi-Won; Youn, Jong-In

    2014-11-01

    Although numerous lasers with different wavelengths are available for laser hair removal, their use in individuals with dark-pigmented skin remains a challenge. The present study aims to develop a numerical heat diffusion model considering skin types over various wavelengths. This numerical mode uses Pennes approximation to represent heat from metabolism, blood perfusion and an external heating source. The heat diffusion model is experimentally validated by using agar-based skin tissue phantoms. Diode lasers with four different wavelengths were used with two antithetical skin models. The pulse width and beam spot size were set to 200 ms and 1 cm(2), respectively. Temperature distribution along the hair structure and skin tissue was examined to determine both thermal confinement and heat transfer to the hair follicle. Experimental results are well matched with the numerical results. The results show that for the light skin model, thermal confinement is well achieved over various wavelengths, and treatment efficacy is expected to be better at a shorter wavelength. Otherwise, for the dark skin model, thermal confinement is poorly achieved as the wavelength decreases (hair tip and the hair root is significantly large compared with the light skin model, which may lead to adverse effects. We believe that the developed numerical model will help to establish optimal laser parameters for different individuals during laser hair removal.

  20. Identification of controlled-complexity thermal therapy models derived from magnetic resonance thermometry images.

    Directory of Open Access Journals (Sweden)

    Ran Niu

    Full Text Available Medical imaging provides information valuable in diagnosis, planning, and control of therapies. In this paper, we develop a method that uses a specific type of imaging--the magnetic resonance thermometry--to identify accurate and computationally efficient site and patient-specific computer models for thermal therapies, such as focused ultrasound surgery, hyperthermia, and thermally triggered targeted drug delivery. The developed method uses a sequence of acquired MR thermometry images to identify a treatment model describing the deposition and dissipation of thermal energy in tissues. The proper orthogonal decomposition of thermal images is first used to identify a set of empirical eigenfunctions, which captures spatial correlations in the thermal response of tissues. Using the reduced subset of eigenfunction as a functional basis, low-dimensional thermal response and the ultrasound specific absorption rate models are then identified. Once identified, the treatment models can be used to plan, optimize, and control the treatment. The developed approach is validated experimentally using the results of MR thermal imaging of a tissue phantom during focused ultrasound sonication. The validation demonstrates that our approach produces accurate low-dimensional treatment models and provides a convenient tool for balancing the accuracy of model predictions and the computational complexity of the treatment models.

  1. Effect of different diode laser powers in photodynamic therapy

    CSIR Research Space (South Africa)

    Maduray, K

    2010-09-01

    Full Text Available (PDT) is a treatment for cancer which requires an interaction between a photosensitizer (PS; drug or dye) and light (laser) of an appropriate wavelength in the presence of tissue molecular oxygen, to produce reactive oxygen species for the destruction... of cancer cells [1]. For PDT to be considered as an effective cancer treatment it should be able to cause the destruction of cancer cells with minimum damage to healthy normal cells. The efficacy of PDT using AlTSPc and ZnTSPc activated with a diode laser...

  2. What will it take for laser driven proton accelerators to be applied to tumor therapy?

    Science.gov (United States)

    Linz, Ute; Alonso, Jose

    2007-09-01

    After many years on the periphery of cancer therapy, the successes of proton and ion beams in tumor therapy are gradually receiving a higher degree of recognition. The considerable construction and acquisition costs are usually invoked to explain the slow market penetration of this favorable treatment modality. Recently, high-intensity lasers have been suggested as a potential, cost-saving alternative to cyclotrons or synchrotrons for oncology. This article will detail the technical requirements necessary for successful implementation of ion beam therapy (IBT)—the general term for proton and heavier-ion therapy. It will summarize the current state of laser acceleration of protons and will outline the very substantial developments still necessary for this technology to be successfully applied to IBT.

  3. Thermal effects in tissues induced by interstitial irradiation of near infrared laser with a cylindrical diffuser

    Science.gov (United States)

    Le, Kelvin; Johsi, Chet; Figueroa, Daniel; Goddard, Jessica; Li, Xiaosong; Towner, Rheal A.; Saunders, Debra; Smith, Nataliya; Liu, Hong; Hode, Tomas; Nordquist, Robert E.; Chen, Wei R.

    2011-03-01

    Laser immunotherapy (LIT), using non-invasive laser irradiation, has resulted in promising outcomes in the treatment of late-stage cancer patients. However, the tissue absorption of laser light limits the clinical applications of LIT in patients with dark skin, or with deep tumors. The present study is designed to investigate the thermal effects of interstitial irradiation using an 805-nm laser with a cylindrical diffuser, in order to overcome the limitations of the non-invasive mode of treatment. Cow liver and rat tumors were irradiated using interstitial fiber. The temperature increase was monitored by thermocouples that were inserted into the tissue at different sites around the cylinder fiber. Three-dimensional temperature distribution in target tissues during and after interstitial laser irradiation was also determined by Proton Resonance Frequency. The preliminary results showed that the output power of laser and the optical parameters of the target tissue determined the light distribution in the tissue. The temperature distributions varied in the tissue according to the locations relative to the active tip of the cylindrical diffuser. The temperature increase is strongly related to the laser power and irradiation time. Our results using thermocouples and optical sensors indicated that the PRF method is reliable and accurate for temperature determination. Although the inhomogeneous biological tissues could result in temperature fluctuation, the temperature trend still can be reliable enough for the guidance of interstitial irradiation. While this study provides temperature profiles in tumor tissue during interstitial irradiation, the biological effects of the irradiation remain unclear. Future studies will be needed, particularly in combination with the application of immunostimulant for inducing tumor-specific immune responses in the treatment of metastatic tumors.

  4. [Thermal therapy of prostate cancer using magnetic nanoparticles].

    Science.gov (United States)

    Johannsen, Manfred; Gneveckow, Uwe; Taymoorian, Kasra; Cho, Chie Hee; Thiesen, Burghard; Scholz, Regina; Waldöfner, Norbert; Loening, Stefan A; Wust, Peter; Jordan, Andreas

    2007-06-01

    A novel method of interstitial heating using magnetic nanoparticles and a direct injection technique has been evaluated in human cancers in recent clinical trials. In prostate cancer, this approach was investigated in two separate phase-I-studies, employing magnetic nanoparticle thermotherapy alone and in combination with permanent seed brachytherapy. The feasibility and good tolerability was shown in both trials, using the first prototype of a magnetic field applicator. As with any other heating technique, this novel approach requires specific tools for planning, quality control and thermal monitoring, based on appropriate imaging and modelling techniques. In these first clinical trials, a newly developed method for planning and non-invasive calculations of the 3-dimensional temperature distribution based on computed tomography could be validated. Limiting factors of this approach at present are patient discomfort at high magnetic field strengths and suboptimal intratumoral distribution of nanoparticles. Until these limitations will be overcome and thermal ablation can safely be applied as a monotherapy, this treatment modality is being evaluated in combination with irradiation in patients with localized prostate cancer.

  5. The effectiveness of low laser therapy in subacromial impingement syndrome: a randomized placebo controlled double-blind prospective study

    Directory of Open Access Journals (Sweden)

    Sebnem Koldas Dogan

    2010-01-01

    Full Text Available OBJECTIVES: Conflicting results were reported about the effectiveness of Low level laser therapy on musculoskeletal disorders. The aim of this study was to investigate the effectiveness of 850-nm gallium arsenide aluminum (Ga-As-Al laser therapy on pain, range of motion and disability in subacromial impingement syndrome. METHODS: A total of 52 patients (33 females and 19 males with a mean age of 53.59±11.34 years with subacromial impingement syndrome were included. The patients were randomly assigned into two groups. Group I (n = 30, laser group received laser therapy (5 joule/cm² at each point over maximum 5-6 painful points for 1 minute. Group II (n = 22, placebo laser group received placebo laser therapy. Initially cold pack (10 minutes was applied to all of the patients. Also patients were given an exercise program including range of motion, stretching and progressive resistive exercises. The therapy program was applied 5 times a week for 14 sessions. Pain severity was assessed by using visual analogue scale. Range of motion was measured by goniometer. Disability was evaluated by using Shoulder Pain and Disability Index. RESULTS: In group I, statistically significant improvements in pain severity, range of motion except internal and external rotation and SPADI scores were observed compared to baseline scores after the therapy (p0.05. CONCLUSIONS: The Low level laser therapy seems to have no superiority over placebo laser therapy in reducing pain severity, range of motion and functional disability.

  6. Medication-Related Osteonecrosis of Jaws: A Low-Level Laser Therapy and Antimicrobial Photodynamic Therapy Case Approach

    Directory of Open Access Journals (Sweden)

    Mariana Comparotto Minamisako

    2016-01-01

    Full Text Available Medication-related osteonecrosis of the jaws (MRONJ can be considered an inability of the alveolar bone to respond to an injury, which frequently leads to severe local and systemic complications. Once the problem is installed, dentist must use all therapeutic approaches recommended. This manuscript reports a successful management of MRONJ handled with antibiotics, conservative debridement, low-level laser therapy (LLLT, and photodynamic therapy (PDT up to 12 months. As healing of MRONJ may be very slow, combined therapeutic approaches are required. Besides the recommended conventional treatment protocol, LLLT and PDT are important tools to contribute to healing and improvement of patient’s quality of life.

  7. Pulsed-laser therapy (GA-As) in combined treatment of post-traumatic swellings and some dermatological disorders

    Science.gov (United States)

    Antipa, Ciprian; Dona, Dumitru; Podoleanu, Adrian Gh.

    1994-02-01

    The effect of a pulsed gallium arsenide infrared laser radiation was studied on 64 patients with post traumatic swellings, allergic vasculitis and varicose crural ulcers, therapy resistant. The soft laser therapy was conducted in combination with classical therapy and was compared with a non irradiated control group of 52 patients treated only by classical therapy. Laser irradiation was directed to the skin damage by laser scanning. Segmental and dermatomic areas of the skin lesions were irradiated by laserpuncture. Therapeutic protocol included an average of nine sessions. The statistical analysis shows a significant difference of the efficiency between Ga-As pulsed laser treated group and the control group, especially in the case of post-traumatic swellings and less in the case of allergic vasculitis. The effects reported by this study are relevant for clinical application of infrared pulsed low lasers in dermatology.

  8. Effect of Low Level Laser Therapy on Proliferation and Differentiation of the Cells Contributing in Bone Regeneration

    OpenAIRE

    Amid, Reza; Kadkhodazadeh, Mahdi; Ahsaie, Mitra Ghazizadeh; Hakakzadeh, Arian

    2014-01-01

    Introduction: Low level laser therapy (LLLT) also known as photobiomodulation, is a treatment that uses low-level lasers or light-emitting diodes (LEDs) to change cellular function and is a clinically well accepted tool in regenerative medicine and dentistry. Considering the variety of laser, exposure, cells and study types, the exact effects of low level laser therapy seems to be unclear. The aim of this study was to review the data published in the field of the effects of low level laser th...

  9. Studies on reducing the thermal loads of solar-pumped solid state lasers; Taiyoko reiki laser no netsufuka teigen ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, K.; Yugami, H.; Naito, H.; Arashi, H. [Tohoku University, Sendai (Japan)

    1997-11-25

    It was intended to reduce the thermal loads of solar-pumped solid state lasers (highly densified solar light is irradiated directly onto a laser medium to cause excitation. No electric power is required for the excitation.). For this purpose, experiments were performed by using a selective permeation film. Solar light includes wavelengths not effective for excitation, which causes heat generation and thermal loads such as lens heating effect and thermal stress compounded refraction, degrading the laser beam quality. The Nd:YAG was used as a laser medium, and a multi-layered film (composed of SiO2 and TiO2) which cuts wavelength below 500 nm as a selective permeation film to cut light having wavelengths not required for excitation. A laser transmitting experiment revealed that the slope efficiency is improved by 27% as compared to not using the film. Beam fluctuation was improved to 45%. Using the selective permeation film has realized more efficient conversion of the solar light into a beam with better quality. The results for calculation of heat lens effect by using temperature distribution simulation showed good agreement with experimental values. Using the selective permeation film can suppress the maximum temperature of a laser rod to 68%, as well as the thermal stress. 9 figs., 2 tabs.

  10. Achilles tendon of wistar rats treated with laser therapy and eccentric exercise

    Directory of Open Access Journals (Sweden)

    Maria Verônica de Souza

    2015-10-01

    Full Text Available ABSTRACTIntroduction:Both laser therapy and eccentric exercises are used in tendon injuries. However, the association of these physiotherapeutic modalities is yet little investigated.Objective:To evaluate the effect of low-level laser therapy associated to eccentric exercise (downhill walking on Achilles tendinopathy of Wistar rats.Method:Eighteen Achilles tendon from 15 adult male Wistar rats were used. Tendons were distributed in six groups (laser, eccentric exercise, laser and eccentric exercise, rest, contralateral tendon, and healthy tendon. Unilateral tendinopathy was surgically induced by transversal compression followed by scarification of tendon fibers. The treatments laser therapy (904 nm, 3J/cm² and/or eccentric exercise (downhill walking; 12 m/min; 50 min/day; 15o inclination treadmill began 24 hours after surgery and remained for 20 days. Clinical and biomechanical analyzes were conducted. Achilles tendon was macroscopically evaluated and the transversal diameter measured. Euthanasia was performed 21 days after lesion induction. Tendons of both limbs were collected and frozen at -20°C until biomechanical analysis, on which the characteristic of maximum load (N, stress at ultimate (MPa and maximum extension (mm were analyzed.Results:Swelling was observed within 72 hours postoperative. No fibrous adhesions were observed nor increase in transversal diameter of tendons. Animals with the exercised tendons, but not treated with laser therapy, presented lower (p=0.0000 locomotor capacity. No difference occurred be-tween groups for the biomechanical characteristics maximum load (p=0.4379, stress at ultimate (p=0.4605 and maximum extension (p=0.3820 evaluated, even considering healthy and contralateral tendons.Conclusion:The concomitant use of low-level laser and the eccentric exercise of downhill walking, starting 24 hours after surgically induced tendinopathy, do not result in a tendon with the same biomechanical resistance or elasticity

  11. Numerical analysis of thermal effect in aluminum alloy by monopulse laser

    Science.gov (United States)

    Gu, Xiuying; Chen, Guibo; Jin, Guangyong; Zhang, Wei; Li, Mingxin

    2014-12-01

    A spatial axisymmetric finite element model is established to investigate the distribution characteristics of temperature field that monopulse millisecond laser act on aluminum alloy. The thermal process of laser acting on aluminum alloy (melting, gasification and temperature drop) is simulated. Using the specific quivalent heat capacity method to simulate the solid-liquid, liquid-gas phase transition of aluminum alloy, and considering the differences of thermal physical parameters between different states (solid-liquid, liquid-gas) of aluminum alloy in the process of numerical simulation. The distribution of temperature field of aluminum alloy caused by the change of energy density, pulse width and spot radius of monopulse millisecond laser are investigated systematically by using numerical simulation model. The numerical results show that the temperature of target no longer rises after reaching the target gasification. Given the pulse width and spot radius, the temperature of target rise as the energy density increases, the laser intensity distribution is gaussian, so the temperature distribution of the target surface also shows Gaussian. The energy absorption mechanism of aluminum alloy is surface absorption mechanism, the temperature gradient in axial of the target is much lager than the temperature gradient in radial of the target surface, so the temperature rise in axial only exists a thin layer of target surface. Given the energy density and spot radius, as the pulse width increases, the power density of laser decreases, therefore the temperature of target center point decreases as the pulse width increases, and the temperature difference becomes small. As the pulse width decreases, the heat transfer in axial reduce, the deposition of energy enhances on the surface. Given the energy density and pulse width, the distribution of the temperature is enlarged as the spot radius increases, but the distribution of the temperature in axial is independent of the spot

  12. Laser Therapy of Irradiated Traumatized Skeletal Muscles and State of Immune System in Animals

    Directory of Open Access Journals (Sweden)

    Nelly Bulyakova

    2011-01-01

    Full Text Available Problems statement: This study was designed to examine the effect of laser therapy on regeneration of traumatized skeletal muscles and on dynamics of immune responses in thymus and bone marrow under ionizing radiation. Approach: After local X-ray radiation of both rat gastrocnemius muscles at a dose 20 Gy or after total γ-irradiation of animals at a semiletal dose 6 Gy, the muscles were damaged considerably as contractile organ (full cut across muscle. Then laser therapy was carried out with a helium-neon laser (632.8 nm or infrared pulsed laser (890 nm, 10 treatments by 3 min during the first 15 or 30 days after trauma.The investigations were performed using histological, biochemical, cytological, cytogenetic and morphometric methods. Results: The received data showed that under ionizing radiation, He-Ne and IR laser irradiation stimulated the regeneration of skeletal muscles, improved the healing of skin-muscle wound and stimulated the prosesses of postradiation recovery in cells of the thymus and bone marrow. The regenerative activity of radiated traumatized muscles and the level of reduction of cytogenetic damages in bone marrow and the thymus varied depending on the period for which regenerative muscles were exposured to laser light, as well as the optical characteristics of lasers and the degree of radiation damages. The early appearance of reactive changes in structure of the thymus and the display them during 60 days point to increasing function of organ. Conclusion: Under local and total ionizing radiation and laser therapy of solely damaged skeletal muscles, positive dynamics of regeneration processes and improvement of cytological and cytogenetic indexes for main immune organs (the thymus and bone marrow were observed. Herewith, the functional loading on thymus increased. We suggest that the findings should be considered in clinical practice.

  13. Immunomodulating effect of laser therapy in patients with microbial eczema

    Science.gov (United States)

    Dudchenko, Mycola O.; Denisenko, Olga I.

    1999-11-01

    While examining 90 patients suffering the microbial eczema (ME), we revealed disorders of the immune system in the majority of them (3/4). It was established that the inclusion of percutaneous laser irradiation of the blood in a course of multimodality treatment of patients with ME caused an immunomodulating action which resulted in an improved ME course in these patients.

  14. Laser treatment of female stress urinary incontinence: optical, thermal, and tissue damage simulations

    Science.gov (United States)

    Hardy, Luke A.; Chang, Chun-Hung; Myers, Erinn M.; Kennelly, Michael J.; Fried, Nathaniel M.

    2016-02-01

    Treatment of female stress urinary incontinence (SUI) by laser thermal remodeling of subsurface tissues is studied. Light transport, heat transfer, and thermal damage simulations were performed for transvaginal and transurethral methods. Monte Carlo (MC) provided absorbed photon distributions in tissue layers (vaginal wall, endopelvic fascia, urethral wall). Optical properties (n,μa,μs,g) were assigned to each tissue at λ=1064 nm. A 5-mm-diameter laser beam and power of 5 W for 15 s was used, based on previous experiments. MC output was converted into absorbed energy, serving as input for ANSYS finite element heat transfer simulations of tissue temperatures over time. Convective heat transfer was simulated with contact cooling probe set at 0 °C. Thermal properties (κ,c,ρ) were assigned to each tissue layer. MATLAB code was used for Arrhenius integral thermal damage calculations. A temperature matrix was constructed from ANSYS output, and finite sum was incorporated to approximate Arrhenius integral calculations. Tissue damage properties (Ea,A) were used to compute Arrhenius sums. For the transvaginal approach, 37% of energy was absorbed in endopelvic fascia layer with 0.8% deposited beyond it. Peak temperature was 71°C, treatment zone was 0.8-mm-diameter, and almost all of 2.7-mm-thick vaginal wall was preserved. For transurethral approach, 18% energy was absorbed in endopelvic fascia with 0.3% deposited beyond it. Peak temperature was 80°C, treatment zone was 2.0-mm-diameter, and only 0.6 mm of 2.4-mm-thick urethral wall was preserved. A transvaginal approach is more feasible than transurethral approach for laser treatment of SUI.

  15. Nonablative minimally invasive thermal therapies in the treatment of symptomatic benign prostatic hyperplasia.

    NARCIS (Netherlands)

    Ancona, F.C.H. d'

    2008-01-01

    PURPOSE OF REVIEW: As all new treatment modalities nonablative thermal therapy for minimal invasive treatment of benign prostatic hyperplasia should be critically analyzed. This review discusses the literature to identify the merits of these so-called minimally invasive treatments and the place they

  16. X-ray analysis of mechanical and thermal effects induced by femtosecond laser treatment of aluminum single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Valette, S. [Laboratoire Traitement du Signal et Instrumentation, Universite Jean Monnet, UMR CNRS 5516, 10 rue Barrouin 42000 Saint-Etienne (France)]. E-mail: stephane.valette@ec-lyon.fr; Le Harzic, R. [Laboratoire Traitement du Signal et Instrumentation, Universite Jean Monnet, UMR CNRS 5516, 10 rue Barrouin 42000 Saint-Etienne (France); Audouard, E. [Laboratoire Traitement du Signal et Instrumentation, Universite Jean Monnet, UMR CNRS 5516, 10 rue Barrouin 42000 Saint-Etienne (France); Huot, N. [Laboratoire Traitement du Signal et Instrumentation, Universite Jean Monnet, UMR CNRS 5516, 10 rue Barrouin 42000 Saint-Etienne (France); Fillit, R. [Ecole Nationale Superieure des Mines de Saint-Etienne, 158 Cours Fauriel, 42023 Saint-Etienne Cedex 2 (France); Fortunier, R. [Ecole Nationale Superieure des Mines de Saint-Etienne, 158 Cours Fauriel, 42023 Saint-Etienne Cedex 2 (France)

    2006-04-30

    Surface marking of aluminum single crystal is performed with femtosecond laser pulses. X-ray analysis allows to measure thermal and mechanical effects induced by the femtosecond laser pulses. These effects are estimated by comparing the pole figures (crystallinity) and the broadening of the diffraction peaks (mechanical contribution) before and after the laser irradiation. The results show that the femtosecond laser treatment ensures a re-crystallization of the structure and the presence of mechanical residual stresses. The analysis of the pole figures provides the sign of a re-crystallization on smaller volumes compared to initial ones. After the laser irradiation, the crystallization is perfectly oriented like the (1 1 0) orientation of the massive sample. Moreover, following the laser treatment, we show that the crystallographic structure is purer than the initial one. We also prove that the laser effect is persistent on a typical scale of 10 {mu}m beyond the surface.

  17. Efficacy of Nd:YAG laser therapy for the treatment of verrucae: a literature review.

    Science.gov (United States)

    Hsu, Vincent M; Aldahan, Adam S; Tsatalis, John P; Perper, Marina; Nouri, Keyvan

    2017-07-01

    Verrucae are benign epithelial proliferations, characteristically 1-20 mm in diameter, caused by human papilloma virus (HPV) infection occurring on the skin and mucosa (Photomed Laser Surg 33(6):338-42, 2015; Lasers Med Sci 29(3):1111-6, 2014). Prevalence of verrucae is 5-20% in children and young adults with peak incidence reported during teenage years (Lasers Med Sci 29(3):1111-6, 2014; J Am Acad Dermatol 22(4):547-66, 1990; J Korean Med Sci 24(5):889-93, 2009). Patients often express significant displeasure with quality of life due to this cosmetic insecurity, as well as functional problems and physical discomfort when they occur on palms of hands and soles of feet. Traditional therapeutic options for warts, such as topical salicyclic acid, topical imiquimod, bleomycin injections, cryotherapy, surgical excision, and electrocautery, have proven somewhat effective but often lead to high recurrence rates or scarring (Photomed Laser Surg 33(6):338-42, 2015). Laser therapy offers an alternative solution by employing selective tissue destruction with minimal risks. We performed a broad literature search in PubMed to obtain all available published articles that studied the treatment of verrucae on the skin with 1064-nm neodymium-doped yttrium aluminum garnet laser. This laser is specifically suited for verruca treatment due to its deeply penetrating 1064-nm wavelength and relatively low risk of pigmentation changes in dark skin types (Photomed Laser Surg 33(6):338-42, 2015). Laser therapy is effective in the treatment of verrucae and has enabled clinicians to provide direct, targeted treatment of warts.

  18. Photothermal cancer therapy by gold-ferrite nanocomposite and near-infrared laser in animal model.

    Science.gov (United States)

    Heidari, M; Sattarahmady, N; Azarpira, N; Heli, H; Mehdizadeh, A R; Zare, T

    2016-02-01

    Surface plasmon resonance effect of gold nanostructures makes them good candidates for photothermal therapy (PTT) application. Herein, gold-ferrite nanocomposite (GFNC) was synthesized and characterized as a photothermal agent in PTT. The aim of this study was to investigate the effect of GFNC upon laser irradiation on treatment of cancer in mice bearing melanoma cancer. Thirty mice received 1.5 × 10(6) B16/F10 cells subcutaneously. After 1 week, the mice bearing solid tumor were divided into four groups: control group (without any treatment), laser group (received laser irradiation without GFNC injection), GFNC group (only received intratumorally GFNC), and GFNC + laser group (received intratumorally GFNC upon laser irradiation). In GFNC + laser group, 200 μL of fluid, 1.3 × 10(-7) mol L(-1) gold nanoparticles, was injected intratumorally and immediately the site of tumor was exposed to continuous wave diode laser beam (808 nm, 1.6 W cm(-2)) for 15 min. All mice but four were euthanized 24 h after treatment to compare the necrotic surface area histologically by using measuring graticule. Statistical analyses revealed significant differences in necrosis extent for GFNC + laser group, compared to other groups. Four subjects (control group and GFNC + laser group, two mice each) were kept for longitudinal study. Histological analyses and tumor volume measurements of the four subjects indicated that tumor in GFNC + laser group was controlled appropriately. It was concluded that combining an 808-nm laser at a power density of 1.6 W cm(-2) with GFNC has a destruction effect in melanoma cancer cells in an animal model.

  19. Five-year comparative study on conventional and laser-assisted therapy of periimplantitis and periodontitis

    Science.gov (United States)

    Bach, Georg; Neckel, Claus P.

    2000-03-01

    Numerous groups have recommended the use of the diode laser to decontaminate infected root and implant surfaces. The aim of this study was to show the outcome after laser assisted and conventional therapy of periimplantitis and periodontitis administering approved treatment protocols. Between 1994 and 1999 a total of 50 patients with periimplantitis (20) and periodontitis (30) were treated in two groups each. Clinical, microbiological and radiographic evaluation was performed before and 6, 12, 24, 36, 48 and 60 months after treatment. In addition to the conventional treatment protocol, flap surgery, the tooth or implant surface was decontaminated with a 810 nm diode laser using 1 Watt output for 20 sec (CW mode). All accessible surfaces were decontaminated at the follow up dates. In the periimplantitis group recurrence of the marker bacteria was higher and faster over time for the conventionally operated patients. Also the clinical and radiographic reevaluation showed significantly better results. The laser group of the periodontitis patients also showed significantly better outcome in terms of clinical evaluation, microbiological counts, radiographic evaluation and tooth loss. In comparison to other long term studies our results for the conventional therapy were adequate, the laser assisted therapy brought up significantly better and reproducible results.

  20. Nd:YAG laser therapy for rectal and vaginal venous malformations.

    Science.gov (United States)

    Gurien, Lori A; Jackson, Richard J; Kiser, Michelle M; Richter, Gresham T

    2017-08-01

    Limited therapeutic options exist for rectal and vaginal venous malformations (VM). We describe our center's experience using Nd:YAG laser for targeted ablation of abnormal veins to treat mucosally involved pelvic VM. Records of patients undergoing non-contact Nd:YAG laser therapy of pelvic VM at a tertiary children's hospital were reviewed. Symptoms, operative findings and details, complications, and outcomes were evaluated. Nine patients (age 0-24) underwent Nd:YAG laser therapy of rectal and/or vaginal VM. Rectal bleeding was present in all patients and vaginal bleeding in all females (n = 5). 5/7 patients had extensive pelvic involvement on MRI. Typical settings were 30 (rectum) and 20-25 W (vagina), with 0.5-1.0 s pulse duration. Patients underwent the same-day discharge. Treatment intervals ranged from 14 to 180 (average = 56) weeks, with 6.1-year mean follow-up. Five patients experienced symptom relief with a single treatment. Serial treatments managed recurrent bleeding successfully in all patients, with complete resolution of vaginal lesions in 40% of cases. No complications occurred. Nd:YAG laser treatment of rectal and vaginal VM results in substantial improvement and symptom control, with low complication risk. Given the high morbidity of surgical resection, Nd:YAG laser treatment of pelvic VM should be considered as first line therapy.

  1. Patterns of Traditional Chinese Medicine Diagnosis in Thermal Laser Acupuncture Treatment of Knee Osteoarthritis

    Directory of Open Access Journals (Sweden)

    Lizhen Wang

    2013-01-01

    Full Text Available Knee osteoarthritis (OA manifests with pain, joint stiffness, and limited function. In traditional Chinese medicine, knee OA is differentiated into three patterns: yang deficiency and cold coagulation, kidney deficiency, and blood stasis. The objective of this study was to determine whether yang deficiency cold coagulation patients respond better to thermal laser acupuncture treatment than do non-yang deficient patients. Fifty-two patients with OA were allocated to group A (yang deficient, n=26 or B (non-yang deficient, n=26. All patients received a 20-min thermal laser acupuncture treatment at acupoint Dubi (ST 35 three times a week for two weeks and twice a week for another four weeks. Outcome assessments were performed immediately after the first treatment, and at weeks 2, 6, and 10. Group A function scores were significantly better than those of Group B at weeks 2 (P=0.049, 6 (P=0.046, and 10 (P=0.042, but no significant differences were found between the two groups in pain and stiffness scores at any time point. No significant adverse effect was observed. The combined 10.6 μm–650 nm laser treatment might be most beneficial to yang deficiency cold coagulation knee OA patients, particularly in improving function.

  2. High temperature thermal behaviour modeling of large-scale fused silica optics for laser facility

    Institute of Scientific and Technical Information of China (English)

    Yu Jing-Xia; He Shao-Bo; Xiang Xia; Yuan Xiao-Dong; Zheng Wan-Guo; Lü Hai-Bing; Zu Xiao-Tao

    2012-01-01

    High temperature annealing is often used for the stress control of optical materials.However,weight and viscosity at high temperature may destroy the surface morphology,especially for the large-scale,thin and heavy optics used for large laser facilities.It is necessary to understand the thermal behaviour and design proper support systems for large-scale optics at high temperature.In this work,three support systems for fused silica optics are designed and simulated with the finite element method.After the analysis of the thermal behaviours of different support systems,some advantages and disadvantages can be revealed.The results show that the support with the optical surface vertical is optimal because both pollution and deformation of optics could be well controlled during annealing at high temperature.Annealing process of the optics irradiated by CO2 laser is also simulated.It can be concluded that high temperature annealing can effectively reduce the residual stress.However,the effects of annealing on surface morphology of the optics are complex.Annealing creep is closely related to the residual stress and strain distribution.In the region with large residual stress,the creep is too large and probably increases the deformation gradient which may affect the laser beam propagation.

  3. Laser weld process monitoring and control using chromatic filtering of thermal radiation from a weld pool

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Cheol Jung; Kim, Min Suk; Baik, Sung Hoon; Chung, Chin Man

    2000-06-01

    The application of high power Nd: YAG lasers for precision welding in industry has been growing quite fast these days in diverse areas such as the automobile, the electronics and the aerospace industries. These diverse applications also require the new developments for the precise control and the reliable process monitoring. Due to the hostile environment in laser welding, a remote monitoring is required. The present development relates in general to weld process monitoring techniques, and more particularly to improved methods and apparatus for real-time monitoring of thermal radiation of a weld pool to monitor a size variation and a focus shift of the weld pool for weld process control, utilizing the chromatic aberration of focusing lens or lenses. The monitoring technique of the size variation and the focus shift of a weld pool is developed by using the chromatic filtering of the thermal radiation from a weld pool. The monitoring of weld pool size variation can also be used to monitor the weld depth in a laser welding. Furthermore, the monitoring of the size variation of a weld pool is independent of the focus shift of a weld pool and the monitoring of the focus shift of a weld pool is independent of the size variation of a weld pool.

  4. Thermal shock tests of $beta;-sic pellets prepared from laser synthesized nanoscale sic powders

    Science.gov (United States)

    Donato, A.; Borsella, E.; Botti, S.; Martelli, S.; Nannetti, C. A.; Mancini, M. R.; Morjan, I.

    1996-10-01

    Nanoscale SiC powders, produced by laser synthesis from gaseous precursors, have been successfully used to prepare sintered pellets. All the sintered samples showed the low temperature β-SiC structures and presented an enhanced thermal conductivity (> 20%) with respect to materials prepared from commercial powders. Samples hardness and toughness, comparable with commercial products, confirmed the good samples quality. The thermal shock tests have been performed by irradiating the pellets with a Nd-YAG pulsed laser (pulse duration and energy: 0.25 μs and 0.18 J or 0.4 ms and 0.65 J). The laser fluence (power density) was increased by reducing the spot size, up to the appearance of a visible surface damage. The threshold values for the structural damage were quantified using a heat flux parameter φ abs√ tp. The measured threshold value rose from ca. 20 MW/m 2 √s for the best materials prepared from commercial SiC powders to ca. 24 MW/m 2√s for the newly developed β-SiC.

  5. Optical and thermal properties in ultrafast laser surface nanostructuring on biodegradable polymer

    Science.gov (United States)

    Yada, Shuhei; Terakawa, Mitsuhiro

    2015-03-01

    We investigate the effect of optical and thermal properties in laser-induced periodic surface structures (LIPSS) formation on a poly-L-lactic acid (PLLA), a biodegradable polymer. Surface properties of biomaterials are known to be one of the key factors in tissue engineering. Methods to process biomaterial surfaces have been studied widely to enhance cell adhesive and anisotropic properties. LIPSS formation has advantages in a dry processing which is able to process complex-shaped surfaces without using a toxic chemical component. LIPSS, however, was difficult to be formed on PLLA due to its thermal and optical properties compared to other polymers. To obtain new perspectives in effect of these properties above, LIPSS formation dependences on wavelength, pulse duration and repetition rate have been studied. At 800 nm of incident wavelength, high-spatial frequency LIPSS (HSFL) was formed after applying 10000 femtosecond pulses at 1.0 J/cm2 in laser fluence. At 400 nm of the wavelength, HSFL was formed at fluences higher than 0.20 J/cm2 with more than 3000 pulses. Since LIPSS was less formed with lower repetition rate, certain heat accumulation may be required for LIPSS formation. With the pulse duration of 2.0 ps, higher laser fluence as well as number of pulses compared to the case of 120 fs was necessary. This indicates that multiphoton absorption process is essential for LIPSS formation. Study on biodegradation modification was also performed.

  6. Thermal analysis of laser interstitial thermotherapy in ex vivo fibro-fatty tissue using exponential functions

    Energy Technology Data Exchange (ETDEWEB)

    Salas, Nelson Jr. [Biomedical Optics and Laser Laboratory, Department of Biomedical Engineering, University of Miami College of Engineering, PO Box 248294, Coral Gables, FL 33124 (United States); Manns, Fabrice [Biomedical Optics and Laser Laboratory, Department of Biomedical Engineering, University of Miami College of Engineering, PO Box 248294, Coral Gables, FL 33124 (United States); Milne, Peter J [Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami School of Medicine, 1638 NW 10th Ave, McKnight Bldg, Miami, FL 33136 (United States); Denham, David B [Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami School of Medicine, 1638 NW 10th Ave, McKnight Bldg, Miami, FL 33136 (United States); Minhaj, Ahmed M [Biomedical Optics and Laser Laboratory, Department of Biomedical Engineering, University of Miami College of Engineering, PO Box 248294, Coral Gables, FL 33124 (United States); Parel, Jean-Marie [Biomedical Optics and Laser Laboratory, Department of Biomedical Engineering, University of Miami College of Engineering, PO Box 248294, Coral Gables, FL 33124 (United States); Robinson, David S [Center for Breast Care, St Luke' s Hospital of Kansas City, 4400 Broadway, Suite 509, Kansas City, MO 64111 (United States)

    2004-05-07

    A therapeutic procedure to treat small, surface breast tumours up to 10 mm in radius plus a 5 mm margin of healthy, surrounding tissue using laser interstitial thermotherapy (LITT) is currently being investigated. The purpose of this study is to analyse and model the thermal and coagulative response of ex vivo fibro-fatty tissue, a model for breast tissue, during experimental laser interstitial thermotherapy at 980 nm. Laser radiation at 980 nm was delivered interstitially through a diffusing tip optical fibre inserted into a fibro-fatty tissue model to produce controlled heating at powers ranging from 3.2 to 8.0 W. Tissue temperature was measured with thermocouples placed at 15 positions around the fibre. The induced coagulation zone was measured on gross anatomical sections. Thermal analysis indicates that a finite sum of exponential functions is an approximate solution to the heat conduction equation that more accurately predicts the time-temperature dependence in tissue prior to carbonization (T < 100 deg. C) during LITT than the traditional model using a single exponential function. Analysis of the ellipsoid coagulation volume induced in tissue indicates that the 980 nm wavelength does not penetrate deep enough in fibro-fatty tissue to produce a desired 30 mm diameter (14.1 x 10{sup 3} mm{sup 3}) coagulation volume without unwanted tissue liquefaction and carbonization.

  7. Thermal analysis of laser interstitial thermotherapy in ex vivo fibro-fatty tissue using exponential functions

    Science.gov (United States)

    Salas, Nelson, Jr.; Manns, Fabrice; Milne, Peter J.; Denham, David B.; Minhaj, Ahmed M.; Parel, Jean-Marie; Robinson, David S.

    2004-05-01

    A therapeutic procedure to treat small, surface breast tumours up to 10 mm in radius plus a 5 mm margin of healthy, surrounding tissue using laser interstitial thermotherapy (LITT) is currently being investigated. The purpose of this study is to analyse and model the thermal and coagulative response of ex vivo fibro-fatty tissue, a model for breast tissue, during experimental laser interstitial thermotherapy at 980 nm. Laser radiation at 980 nm was delivered interstitially through a diffusing tip optical fibre inserted into a fibro-fatty tissue model to produce controlled heating at powers ranging from 3.2 to 8.0 W. Tissue temperature was measured with thermocouples placed at 15 positions around the fibre. The induced coagulation zone was measured on gross anatomical sections. Thermal analysis indicates that a finite sum of exponential functions is an approximate solution to the heat conduction equation that more accurately predicts the time-temperature dependence in tissue prior to carbonization (T deep enough in fibro-fatty tissue to produce a desired 30 mm diameter (14.1 × 103 mm3) coagulation volume without unwanted tissue liquefaction and carbonization.

  8. Transient thermal and nonthermal electron and phonon relaxation after short-pulsed laser heating of metals

    Energy Technology Data Exchange (ETDEWEB)

    Giri, Ashutosh; Hopkins, Patrick E., E-mail: phopkins@virginia.edu [Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States)

    2015-12-07

    Several dynamic thermal and nonthermal scattering processes affect ultrafast heat transfer in metals after short-pulsed laser heating. Even with decades of measurements of electron-phonon relaxation, the role of thermal vs. nonthermal electron and phonon scattering on overall electron energy transfer to the phonons remains unclear. In this work, we derive an analytical expression for the electron-phonon coupling factor in a metal that includes contributions from equilibrium and nonequilibrium distributions of electrons. While the contribution from the nonthermal electrons to electron-phonon coupling is non-negligible, the increase in the electron relaxation rates with increasing laser fluence measured by thermoreflectance techniques cannot be accounted for by only considering electron-phonon relaxations. We conclude that electron-electron scattering along with electron-phonon scattering have to be considered simultaneously to correctly predict the transient nature of electron relaxation during and after short-pulsed heating of metals at elevated electron temperatures. Furthermore, for high electron temperature perturbations achieved at high absorbed laser fluences, we show good agreement between our model, which accounts for d-band excitations, and previous experimental data. Our model can be extended to other free electron metals with the knowledge of the density of states of electrons in the metals and considering electronic excitations from non-Fermi surface states.

  9. Transient thermal and nonthermal electron and phonon relaxation after short-pulsed laser heating of metals

    Science.gov (United States)

    Giri, Ashutosh; Hopkins, Patrick E.

    2015-12-01

    Several dynamic thermal and nonthermal scattering processes affect ultrafast heat transfer in metals after short-pulsed laser heating. Even with decades of measurements of electron-phonon relaxation, the role of thermal vs. nonthermal electron and phonon scattering on overall electron energy transfer to the phonons remains unclear. In this work, we derive an analytical expression for the electron-phonon coupling factor in a metal that includes contributions from equilibrium and nonequilibrium distributions of electrons. While the contribution from the nonthermal electrons to electron-phonon coupling is non-negligible, the increase in the electron relaxation rates with increasing laser fluence measured by thermoreflectance techniques cannot be accounted for by only considering electron-phonon relaxations. We conclude that electron-electron scattering along with electron-phonon scattering have to be considered simultaneously to correctly predict the transient nature of electron relaxation during and after short-pulsed heating of metals at elevated electron temperatures. Furthermore, for high electron temperature perturbations achieved at high absorbed laser fluences, we show good agreement between our model, which accounts for d-band excitations, and previous experimental data. Our model can be extended to other free electron metals with the knowledge of the density of states of electrons in the metals and considering electronic excitations from non-Fermi surface states.

  10. Laser and light-based therapy for cutaneous and soft-tissue metastases of malignant melanoma: a systematic review.

    Science.gov (United States)

    Austin, Evan; Mamalis, Andrew; Ho, Derek; Jagdeo, Jared

    2017-05-01

    Invasive cutaneous melanoma is a growing health concern. Although surgical excision can effectively treat in situ tumors, use for metastatic melanoma is limited. Laser and light-based therapies may be a valuable palliative treatment option for patients with stage III and stage IV cutaneous metastatic melanoma. Our goal is to review the published literature and provide evidence-based recommendations on laser and light-based palliative therapies for metastatic melanoma. A search of the databases Pubmed, EMBASE, Web of Science, and CINAHL was performed on March 10, 2016. Key search terms were related to melanoma, laser, and light-based modalities. Our search initially identified 13,923 articles and 27 original articles met inclusion criteria for our review. Grade of recommendation: C for non-fractionated carbon dioxide laser, Grade of recommendation: D for fractionated carbon dioxide laser, ruby laser, neodymium laser, near-infrared diode laser, and photodynamic therapy. Non-fractionated carbon dioxide laser had the best palliative efficacy of the reviewed laser and light-based therapies, while other treatment modalities may have potential as adjunctive therapy to standard of care.

  11. Harmonic scalpel versus flexible CO2 laser for tongue resection: A histopathological analysis of thermal damage in human cadavers

    Directory of Open Access Journals (Sweden)

    Wolf Tamir

    2011-08-01

    Full Text Available Abstract Background Monopolar cautery is the most commonly used surgical cutting and hemostatic tool for head and neck surgery. There are newer technologies that are being utilized with the goal of precise cutting, decreasing blood loss, reducing thermal damage, and allowing faster wound healing. Our study compares thermal damage caused by Harmonic scalpel and CO2 laser to cadaveric tongue. Methods Two fresh human cadaver heads were enrolled for the study. Oral tongue was exposed and incisions were made in the tongue akin to a tongue tumor resection using the harmonic scalpel and flexible C02 laser fiber at various settings recommended for surgery. The margins of resection were sampled, labeled, and sent for pathological analysis to assess depth of thermal damage calculated in millimeters. The pathologist was blinded to the surgical tool used. Control tongue tissue was also sent for comparison as a baseline for comparison. Results Three tongue samples were studied to assess depth of thermal damage by harmonic scalpel. The mean depth of thermal damage was 0.69 (range, 0.51 - 0.82. Five tongue samples were studied to assess depth of thermal damage by CO2 laser. The mean depth of thermal damage was 0.3 (range, 0.22 to 0.43. As expected, control samples showed 0 mm of thermal damage. There was a statistically significant difference between the depth of thermal injury to tongue resection margins by harmonic scalpel as compared to CO2 laser, (p = 0.003. Conclusion In a cadaveric model, flexible CO2 laser fiber causes less depth of thermal damage when compared with harmonic scalpel at settings utilized in our study. However, the relevance of this information in terms of wound healing, hemostasis, safety, cost-effectiveness, and surgical outcomes needs to be further studied in clinical settings.

  12. The effects of photodynamic laser therapy in the treatment of marginal chronic periodontitis

    Science.gov (United States)

    Chifor, Radu; Badea, Iulia; Avram, Ramona; Chifor, Ioana; Badea, Mîndra Eugenia

    2016-03-01

    The aim of this study was to assess the effects of the antimicrobial photodynamic laser therapy performed during the treatment of deep periodontal disease by using 40 MHz high frequency ultrasonography. The periodontal data recorded during the clinical examination before each treatment session were compared with volumetric changes of the gingiva measured on periodontal ultrasound images. The results show a significant decrease of gingival tissue inflammation proved both by a significant decrease of bleeding on probing as well as by a decrease of the gingival tissues volume on sites where the laser therapy was performed. Periodontal tissues that benefit of laser therapy besides classical non-surgical treatment showed a significant clinical improvement of periodontal status. Based on these findings we were able to conclude that the antimicrobial photodynamic laser therapy applied on marginal periodontium has important anti-inflamatory effect. The periodontal ultrasonography is a method which can provide useful data for assessing the volume changes of gingival tissues, allowing a precise monitoring of marginal periodontitis.

  13. Laser Therapy for an Obstructing Primary Tracheal Lymphoma in a Patient With AIDS

    Directory of Open Access Journals (Sweden)

    Brian E Louie

    2005-01-01

    Full Text Available A patient with AIDS presented with progressive dyspnea leading to respiratory failure with near complete airway obstruction due to primary tracheal lymphoma. Laser therapy was used locally to debulk the tumour, which facilitated extubation and led to definitive treatment with chemotherapy. Alternatives for local airway control are discussed.

  14. Helium-3 and helium-4 acceleration by high power laser pulses for hadron therapy

    Directory of Open Access Journals (Sweden)

    S. S. Bulanov

    2015-06-01

    Full Text Available The laser driven acceleration of ions is considered a promising candidate for an ion source for hadron therapy of oncological diseases. Though proton and carbon ion sources are conventionally used for therapy, other light ions can also be utilized. Whereas carbon ions require 400 MeV per nucleon to reach the same penetration depth as 250 MeV protons, helium ions require only 250 MeV per nucleon, which is the lowest energy per nucleon among the light ions (heavier than protons. This fact along with the larger biological damage to cancer cells achieved by helium ions, than that by protons, makes this species an interesting candidate for the laser driven ion source. Two mechanisms (magnetic vortex acceleration and hole-boring radiation pressure acceleration of PW-class laser driven ion acceleration from liquid and gaseous helium targets are studied with the goal of producing 250 MeV per nucleon helium ion beams that meet the hadron therapy requirements. We show that He^{3} ions, having almost the same penetration depth as He^{4} with the same energy per nucleon, require less laser power to be accelerated to the required energy for the hadron therapy.

  15. Fractional laser-mediated photodynamic therapy of high-risk basal cell carcinomas

    DEFF Research Database (Denmark)

    Haak, C S; Togsverd-Bo, K; Thaysen-Petersen, D

    2015-01-01

    BACKGROUND: Photodynamic therapy (PDT) is approved for selected nodular basal cell carcinomas (nBCC) but efficacy is reduced for large and thick tumours. Ablative fractional lasers (AFXL) facilitate uptake of methyl aminolaevulinate (MAL) and may thus improve PDT outcome. OBJECTIVES: To evaluate...

  16. Automatized securing definition for laser therapy indications in cases of noncomplicated caries

    Science.gov (United States)

    Oleinik, Olga I.; Popova, Olga

    1995-04-01

    In this article we discuss the methods of definition of indication for laser therapy on the base of findings of a priori systematization of diagnostic caries signs with the purpose of reducing their volume and exposing the most informative of them used in the procedure of specified classification of biomedical objects conditions, forming graphic base of the recommendations in choice of treatment methods.

  17. In vivo studies of low level laser (light) therapy for traumatic brain injury

    Science.gov (United States)

    Xuan, Weijun; Wu, Qiuhe; Huang, Ying-Ying; Ando, Takahiro; Huang, Liyi; Hamblin, Michael R.

    2012-03-01

    Low-level laser (or light) therapy (LLLT) is attracting growing interest to treat both stroke and traumatic brain injury (TBI). The fact that near-infrared light can penetrate into the brain allows non-invasive treatment to be carried out with a low likelihood of treatment-related adverse events. It is proposed that red and NIR light is absorbed by chromophores in the mitochondria of cells leading to changes in gene transcription and upregulation of proteins involved in cell survival, antioxidant production, collagen synthesis, reduction of chronic inflammation and cell migration and proliferation. We developed a mouse model of controlled cortical impact (CCI) TBI and examined the effect of 0, 1, 3, and 14 daily 810-nm CW laser treatments in the CCI model as measured by neurological severity score and wire grip and motion test. 1 laser Tx gave a significant improvement while 3 laser Tx was even better. Surprisingly 14 laser Tx was no better than no treatment. Histological studies at necropsy suggested that the neurodegeneration was reduced at 14 days and that the cortical lesion was repaired by BrdU+ve neural progenitor (stem) cells at 28 days. Transcranial laser therapy is a promising treatment for acute (and chronic TBI) and the lack of side-effects and paucity of alternative treatments encourages early clinical trials.

  18. Anomalous subsurface thermal behavior in tissue mimics upon near infrared irradiation mediated photothermal therapy.

    Science.gov (United States)

    Ghosh, Soham; Sahoo, Nilamani; Sajanlal, P R; Sarangi, Nirod Kumar; Ramesh, Nivarthi; Panda, Tapobrata; Pradeep, T; Das, Sarit Kumar

    2014-03-01

    Photothermal therapy using (Near Infrared) NIR region of EM spectrum is a fast emerging technology for cancer therapy. Different types of nanoparticles may be used for enhancing the treatment. Though the treatment protocols are developed based on experience driven estimated temperature increase in the tissue, it is not really known what spatiotemporal thermal behavior in the tissue is. In this work, this thermal behavior of tissue models is investigated with and without using nanoparticles. An increased temperature inside tissue compared to surface is observed which is counter intuitive from the present state of knowledge. It is shown from fiber level microstructure that this increased temperature leads to enhanced damage at the deeper parts of biomaterials. Nanoparticles can be utilized to control this temperature increase spatially. A multiple scattering based physical model is proposed to explain this counterintuitive temperature rise inside tissue. The results show promising future for better understanding and standardizing the protocols for photothermal therapy.

  19. Insights into a microwave susceptible agent for minimally invasive microwave tumor thermal therapy.

    Science.gov (United States)

    Shi, Haitang; Liu, Tianlong; Fu, Changhui; Li, Linlin; Tan, Longfei; Wang, Jingzhuo; Ren, Xiangling; Ren, Jun; Wang, Jianxin; Meng, Xianwei

    2015-03-01

    This work develops a kind of sodium alginate (SA) microcapsules as microwave susceptible agents for in vivo tumor microwave thermal therapy for the first time. Due to the excellent microwave susceptible properties and low bio-toxicity, excellent therapy efficiency can be achieved with the tumor inhibiting ratio of 97.85% after one-time microwave thermal therapy with ultralow power (1.8 W, 450 MHz). Meanwhile, the mechanism of high microwave heating efficiency was confirmed via computer-simulated model in theory, demonstrating that the spatial confinement efficiency of microcapsule walls endows the inside ions with high microwave susceptible properties. This strategy offers tremendous potential applications in clinical tumor treatment with the benefits of safety, reliability, effectiveness and minimally invasiveness.

  20. Laser-induced thermal characterization of nano Ag metal dispersed ceramic alumina matrix

    Science.gov (United States)

    George, Sajan D.; Anapara, Aji A.; Warrier, K. G. K.; Radhakrishnan, P.; Vallabhan, C. P. G.; Nampoori, V. P. N.

    2003-04-01

    In this paper, we report the measurements of thermal diffusivity of nano Ag metal dispersed ceramic alumina matrix sintered at different temperatures using laser induced non-destructive photoacoustic technique. Measurements of thermal diffusivity also have been carried out on specimens with various concentration of nano metal. Analysis of the data is done on the basis of one-dimensional model of Rosencwaig and Gersho. The present measurements on the thermal diffusivity of nano metal dispersed ceramic alumina shows that porosity has a great influence on the heat transport and the thermal diffusivity value. The present analysis also shows that the inclusion of nano metal into ceramic matrix increases its interconnectivity and hence the thermal diffusivity value. The present study on the samples sintered at different temperature shows that the porosity of the ceramics varies considerably with the change in sintering temperature. The results are interpreted in terms of phonon assisted heat transfer mechanism and the exclusion of pores with the increase in sintering temperature.