• Title/Summary/Keyword: Pulsed Nd:YAG laser

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A STUDY OF ANALGESIC EFFECT ON PULP INDUCED BY PULSED Nd : YAG LASER (Pulsed Nd ; YGA 레이저의 치수마취효과에 관한 연구)

  • Kim, Do-Hyeong;Lee, Chang-Seop;Lee, Sang-Ho
    • JOURNAL OF THE KOREAN ACADEMY OF PEDTATRIC DENTISTRY
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    • v.24 no.1
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    • pp.301-312
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    • 1997
  • The purpose of this study was to evaluate the analgesic effect on pulp induced by pulsed Nd : YAG laser according to the power density, irradiated time and the method of application (Non-contact vs contact) in vivo. Experiments were carried out on 90 volunteers who have sound 4 canines. Each canine was grouped by the intensity and the time of irradiation of pulsed Nd : YAG laser was measured. Mean EPT response(units) was measured at 5 min, 30 min, and 60 min after irradiation with various intensity(1.5-3W, 15-30Hz), irradiated time (1.5min, 3min), and application method (Non-contact and contact). The results were as follows: 1. 5 minutes after irradiation, the mean EPT response(units) was increased by 32 % in the non-contact method and by 35% in the contact method of application. Which showed significant difference in mean EPT response(units) compared to not-lased canine in each groups(P<0.05). 2. The mean EPT response(units) with irradiating condition according to the various laser intensity, and the irradiation time stastically did not show significant difference in each groups as time elapsed. 3. There was no significant difference between the non-contact and contact method in the mean EPT response(units). 4. The mean EPT response(units) returned to the baseline value within 30 miuntes. In regard to the above results, the analgesic effect on pulp induced by pulsed Nd : YAG laser resulted a slight increase of pulpal pain threshold, but it was not as high as to replace the role of drug analgesia as whole. This technique can be used for inducing pulpal analgesia as adjunct to other pain control methods and is needed to develop better analgesic effects.

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A Study On The Junctional Epithelial Downgrowth After DeEpithelization Using Pulsed Nd : YAG Laser In Rat Peiodontal Bone Defect Filled With Calcium Carbonate (백서 치주 골결손부에 calcium carbonate 이식 및 pulsed Nd:YAG 레이저에 의한 치은상피의 제거 후 접합상피의 치유양상)

  • Jeong, Cheol-Woong;Chung, Hyun-Ju
    • Journal of Periodontal and Implant Science
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    • v.26 no.1
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    • pp.276-292
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    • 1996
  • The purpose of this study was to evaluate whether removal of gingival epithelium with pulsed Nd :YAG laser could inhibit the downgrowth of junctional epithelium after alloplastic material grafting in periodontal bone defect. The periodontal bone defects were created surgically on the palatal aspect of the upper right and left molar teeth in 30 rats and filled with resorbable calcium carbonate($Biocoral\;450^{(R)}$: Inoteb, France). The control sites(right molar area) was sutured. The test side (left molar area) received controlled deepithelization of the oral and sulcular epithelium with pulsed Nd:YAG laser($Sunrise\;Maste^{(R)}$: Sunrise Technologies, U.S.A.) under the mode of 1.75W, 15Hz, 116mJ/pulse and was sutured. The control and test sites were evaluated clinically and histologically, at 1, 3, 7, 14, and 28 days postoperation. Clinically, the gingiva showed normal color and shape at the 5th day in the control site and at the 10th day in the test sites. Histologically, the junctional epithelium was formed at the 7th day in the control sites and at the 14th day in the test sites, and the long JE attachment were observed at the 28th day in both sites. The attachment of connective tissue to root surface was observed initially at the 7th day in the control sites and at the 14th day in the test sites, and completed at the 28th day in both sites. In summary, these results showed that the removal of oral epithelium using pulsed Nd:YAG Laser could not prevent epithelial downgrowth after alloplastic material implantation in rat periodontal bone defect.

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The high repetition operating characteristics of pulsed Nd:YAG laser by parallel mesh and alternating charge-discharge system (병렬 메쉬 및 교번 충.방전 방식에 의한 펄스형 Nd:YAG 레이저의 고반복 동작특성에 관한 연구)

  • Park, K.R.;Kim, B.G.;Hong, J.H.;Kim, W.Y.;Kim, H.J.;Cho, J.S.
    • Proceedings of the KIEE Conference
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    • pp.1060-1062
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    • 1999
  • Pulsed Nd:YAG laser is used widely for materials processing and instrumentation. It is very important to control the laser energy density in materials processing by a pulsed Nd:YAG laser. A pulse repetition rate and a pulse width are regarded as the most dominant factors to control the energy density of laser beam. In this study, the alternating charge-discharge system was designed to adjust a pulse repetition rate. And the parallel mesh is added to increase laser output power. This system is controlled by one chip microprocessor and allows to replace an expensive condenser for high frequency to a cheap condenser for low frequency. In addition, we have investigated the current pulse shape of flashlamp and the operating characteristics of a pulsed Nd:YAG laser. As a result, it is found that the laser output of the power supply using the parallel mesh and the alternating charge-discharge system is not less than that of typical power supply. As the pulse repetition rate rises from 10pps to 110pps by the step of 20pps at 1000V and 1200V, it is found that the laser efficiency decreases but the laser output power increases about 5W at each step.

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Development of high repetition rate and high power pulsed Nd:YAG laser power supply using ZCS resonant converter (ZCS공진형 컨버터를 적용한 고반복 대출력 펄스형 Nd:YAG 레이저 전원장치 개발)

  • Joe, K.Y.;Kim, E.S.;Byun, Y.B.;Kim, H.J.;Park, J.M.;Lee, H.W.
    • Proceedings of the KIEE Conference
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    • pp.514-517
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    • 1996
  • Zero current switching(ZCS) series resonant converter is used to control laser power density in a pulsed Nd:YAG laser power supply. The high power and high repetition rate paused Nd:YAG laser is designed and fabricated to control current pulse width and pulse repetition rate in the double elliptical laser oscillator. In order to find out operational characteristics of pulsed Nd:YAG laser, the electrical properties of driving power supply and laser output power are investigated and experimented by changing of the current pulse width from 200uS to 350uS(step 50uS) and pulse repetition rate range of 500pps(pulse per second) to 1150pps. From that result, we obtaind maximum efficiency of 1.83% and maximum laser output or 220W at the condition of 350 uS and 1150pps with one Nd:YAG rod), and obtained that of more than 400W with two laser head connecting series.

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A Study on the Weldability of Magnesium Alloy by Laser Heat Source (III) - Butt Weldability of Sand Casting Magnesium Alloy using Pulsed Nd:YAG Laser - (레이저 열원을 이용한 마그네슘 합금의 용접성에 관한 연구 (III) - Pulsed Nd:YAG 레이저를 이용한 사형주조 마그네슘 합금의 맞대기 용접성 -)

  • Kim, Jong-Do;Lee, Jung-Han;Lee, Mun-Yong
    • Journal of Welding and Joining
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    • v.31 no.2
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    • pp.57-62
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    • 2013
  • Magnesium has good castability and limited workability, so its products have been manufactured by almost casting processes. In this study, a pulsed Nd:YAG laser was used to butt-weld the sand casting magnesium alloys. And the effect of welding conditions such as peak power, pulse width, welding speed was evaluated in detail. As a result of this study, large underfill and plenty of spatter taken place under the conditions with high peak power. Thus, it is recommended to use low peak power and long pulse width to obtain good welds with deep penetration. It is also confirmed that the welding speed and pps(pulse per second) are directly connected at weld defects such as underfill, porosity.

The Removal of Mucocele and Ranula using the Pulsed Nd:YAG Laser (펄스형 Nd:YAG 레이저를 이용한 점액류와 하마종의 치료)

  • Suh, Bong-Jik;Chang, Kee-Wan;Shin, Keum-Back
    • Journal of Oral Medicine and Pain
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    • v.25 no.4
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    • pp.403-411
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    • 2000
  • The authors experienced a non-painful, elevated, dome-shaped lesion on lower lip in Korean male of 22-year-old and a non-painful, elevated, dome-shape lesion on left side of mouth floor in Korean female of 36-year-old. And diagnosed the lesions as a mucocele and a ranula respectively, based on the comprehensive evaluation of data obtained from history taking, clinical and radiologic examination and histopathological findings. In these cases, the authors removed mucocele and ranula using the pulsed Nd:YAG laser with advantage of good hemostatic effect, and so we could minimize improper tissue destruction during operation. The excisional wounds of lower lip and mouth floor had a good healing process without any symptom of pain and any signs of bleeding and infection.

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The output characteristics of pulsed Nd:YAG laser with voltage variable capacitor-charging system (충전전압 가변방식을 이용한 펄스형 Nd:YAG 레이저의 출력특성에 관한 연구)

  • Moon, D.S.;Hong, J.H.;Song, K.Y.;Song, W.J.;Kim, K.H.;Kim, H.J.
    • Proceedings of the KIEE Conference
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    • pp.1703-1705
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    • 2001
  • The pulsed Nd:YAG laser is used widely for materials processing and medical instrument etc. It is important to control the laser energy in those fields using a pulsed Nd:YAG laser. In this paper, constant-frequency current resonant half-bridge inverter and Cockcroft-Walton circuit are used to charge the energy storage capacitor variably. This laser power supply is designed and fabricated which has no high-voltage transformer, less switching losses, compact size and capability in varying the laser output power. Also, the output characteristics of this Nd:YAG laser system are investigated. The tested results are described.

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A Study on the control of output power and pulse repetition rate in pulsed Nd:YAG laser (펄스형 Nd:YAG 레이저의 출력 에너지 및 펄스 반복률 제어에 관한 연구)

  • Park, K.R.;Kim, B.G.;Moon, D.S.;Hong, J.H.;Kim, W.Y.;Kang, U.;Kim, H.J.;Cho, J.S.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.74-77
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    • 2000
  • A pulsed Nd:YAG laser has been used in a wide variety of fields : measuring, material processing and so on. In a material processing, it is very important to control the laser energy density. A pulse repetition rate and a pulse width are regarded as the most dominant factors to control the energy density of laser beam. In this study, pulsed Nd:YAG laser system was designed and manufactured to control the laser output usefully and easily. This system adopted the sequential charge and discharge circuit is controlled by 80196 micro- processor. As a result, it is found that laser output is controlled minutely by changing laser input and pulse repetition rate, and usefully by using 80196 microprocessor.

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Characteristics of Output Energy and Optical Parameters in Welding of Braun Tubes by Pulsed Nd:YAG Laser (펄스 Nd:YAG 레이저에 의한 브라운관 부품의 용접시 빔의 출력특성과 광학변수)

  • Kim Jong-Do;Ha Seung-Hyup
    • Laser Solutions
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    • v.8 no.1
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    • pp.27-37
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    • 2005
  • During laser spot welding of the braun tube electron gun, phenomena such as serious spattering and oxidative reaction, etc. were occurred. The spatter occurred from weld pool affects the braun tube, namely it blocks up a very small hole on the shadow mask and causes short circuit between two poles of the electron gun. We guessed that high power density and oxidative reaction are main sources of these problems. So, we studied to prevent and to reduce spatter occurring in spot welding of the braun tube electron gun using pulsed Nd:YAG laser. The characteristics of laser output power was estimated, and the loss of laser energy by optical parameter and spatter was measured by powermeter. The effects of welding parameters, laser defocused distance and incident angle, were investigated on the shape and penetration depth of the laser welded bead in flare and flange joints. From these results, the laser peak power was a major factor to control penetration depth and to occur spatter. It was found that the losses of laser energy by optic parameter and sticked spatter affect seriously laser weldability of thin sheets.

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