Passively Q-switched lasers: short pulse duration, single-frequency sources

2002 ◽  
Author(s):  
D. Welford
Keyword(s):  
Pulse Duration ◽  
Short Pulse ◽  
Single Frequency ◽  
Short Pulse Duration

Q-switched all-fiber laser with short pulse duration based on tungsten diselenide

Laser Physics ◽  
2018 ◽  
Vol 28 (5) ◽  
pp. 055104 ◽  
Author(s):  
Wenyi Li ◽  
Yuyi OuYang ◽  
Guoli Ma ◽  
Mengli Liu ◽  
Wenjun Liu
Keyword(s):  
Fiber Laser ◽  
Pulse Duration ◽  
Short Pulse ◽  
Tungsten Diselenide ◽  
Short Pulse Duration

scholarly journals Q-Switch Nd:YAG Laser-Assisted Decontamination of Implant Surface

2019 ◽  
Vol 7 (4) ◽  
pp. 99 ◽  
Author(s):  
Namour ◽  
El Mobadder ◽  
Magnin ◽  
Peremans ◽  
Verspecht ◽  
...  
Keyword(s):  
Pulse Duration ◽  
Nd:Yag Laser ◽  
Yttrium Aluminum Garnet ◽  
Short Pulse ◽  
Sem Analysis ◽  
P Value ◽  
Implant Surface ◽  
Contact Mode ◽  
Short Pulse Duration ◽  
Clean Contaminated

Peri-implantitis (PI) is an inflammatory disease of peri-implant tissues, it represents the most frequent complication of dental implants. Evidence revealed that microorganisms play the chief role in causing PI. The purpose of our study is to evaluate the cleaning of contaminated dental implant surfaces by means of the Q-switch Nd:YAG (Neodymium-doped Yttrium Aluminum Garnet) laser and an increase in temperature at lased implant surfaces during the cleaning process. Seventy-eight implants (titanium grade 4) were used (Euroteknika, Sallanches, France). Thirty-six sterile implants and forty-two contaminated implants were collected from failed clinical implants for different reasons, independent from the study. Thirty-six contaminated implants were partially irradiated by Q-switch Nd:YAG laser (1064 nm). Six other contaminated implants were used for temperature rise evaluation. All laser irradiations were calibrated by means of a powermetter in order to evaluate the effective delivered energy. The irradiation conditions delivered per pulse on the target were effectively: energy density per pulse of 0.597 J/cm2, pick powers density of 56 mW/cm2, 270 mW per pulse with a spot diameter of 2.4 mm, and with repetition rate of 10 Hz for pulse duration of 6 ns. Irradiation was performed during a total time of 2 s in a non-contact mode at a distance of 0.5 mm from implant surfaces. The parameters were chosen according to the results of a theoretical modeling calculation of the Nd:YAG laser fluency on implant surface. Evaluation of contaminants removal showed that the cleaning of the irradiated implant surfaces was statistically similar to those of sterile implants (p-value ≤ 0.05). SEM analysis confirmed that our parameters did not alter the lased surfaces. The increase in temperature generated at lased implant surfaces during cleaning was below 1 °C. According to our findings, Q-switch Nd:YAG laser with short pulse duration in nanoseconds is able to significantly clean contaminated implant surfaces. Irradiation parameters used in our study can be considered safe for periodontal tissue.

Point source of UV-radiation with a frequency of 1 khz and short pulse duration

2012 ◽  
Vol 54 (11) ◽  
pp. 1276-1279 ◽  
Author(s):  
E. Kh. Baksht ◽  
V. F. Tarasenko ◽  
Yu. V. Shut’ko ◽  
M. V. Erofeev
Keyword(s):  
Point Source ◽  
Pulse Duration ◽  
Uv Radiation ◽  
Short Pulse ◽  
Short Pulse Duration

Forming Fine V-Grooves on a Tungsten Carbide Workpiece with a PCD Electrode by EDM

2007 ◽  
Vol 329 ◽  
pp. 631-636 ◽  
Author(s):  
Sadao Sano ◽  
Kiyoshi Suzuki ◽  
Wei Li Pan ◽  
Manabu Iwai ◽  
Yoshihiko Murakami ◽  
...  
Keyword(s):  
Tungsten Carbide ◽  
Pulse Duration ◽  
Flat Surface ◽  
Short Pulse ◽  
Chemical Vapor ◽  
Polycrystalline Diamond ◽  
Chemical Vapor Deposition Diamond ◽  
Electrically Conductive ◽  
Short Pulse Duration ◽  
Low Wear

Polycrystalline diamond (PCD) exhibits a thermal conductivity similar to that of the electrically conductive chemical vapor deposition diamond (EC-CVD diamond) found to function as zero-wear electrodes at short pulse duration. In this study, PCD was used as electrodes applied to EDM on tungsten carbide. Two kinds of PCD (CTB-010 and CTH-025) with a flat surface were used. The wear of the PCD electrodes was about 1.5% for very short pulse duration such as te=1μs, but it was zero wear at te=30μs, though the wear of a Cu-W electrode was 10% even on the machine recommended conditions for the low wear. EDM experiment using a V-shaped PCD electrode with an included angle of 45° was also carried out and the performance was compared with the case using a V-shaped Cu-W electrode. Under the conditions of a no load voltage of 60V, a set peak current of 2A, and a medium pulse duration of te=15μs, there was no wear on PCD electrodes when observed under the SEM, whereas a 50μm-deep wear on the Cu-W electrodes even under the machine recommended condition for the low wear was observed.

scholarly journals Effect of microstructure on short pulse duration shock initiation of TATB and initial response mechanism

2020 ◽  
Vol 16 (2) ◽  
pp. 374-380
Author(s):  
Jun Wang ◽  
Wei Cao ◽  
Xiang-li Guo ◽  
Bi-bo Cheng ◽  
Lu-lu Zhao ◽  
...  
Keyword(s):  
Pulse Duration ◽  
Short Pulse ◽  
Initial Response ◽  
Response Mechanism ◽  
Shock Initiation ◽  
Short Pulse Duration ◽  
Effect Of Microstructure

The short pulse duration limit for KrF laser systems

2005 ◽  
Author(s):  
I.N. Ross ◽  
P. Simon ◽  
S. Szatmari ◽  
P. Matousek ◽  
K. Osvay ◽  
...  
Keyword(s):  
Pulse Duration ◽  
Short Pulse ◽  
Short Pulse Duration ◽  
Krf Laser ◽  
Laser Systems

scholarly journals Comparison of Maximum Tolerated Muscle Torques Produced by 2 Pulse Durations

2009 ◽  
Vol 89 (8) ◽  
pp. 851-857 ◽  
Author(s):  
Wayne B. Scott ◽  
James B. Causey ◽  
Tara L. Marshall
Keyword(s):  
Pulse Duration ◽  
Short Pulse ◽  
Neuromuscular Electrical Stimulation ◽  
Knee Extensor ◽  
Muscle Forces ◽  
Pain Thresholds ◽  
Short Pulse Duration ◽  
Medical Histories ◽  
Duration Condition ◽  
Muscle Torques

BackgroundNeuromuscular electrical stimulation (NMES) is an effective therapeutic technique for strengthening weak muscles. A positive dose-response relationship exists between the elicited muscle forces during training and strength (force-generating capacity) gains. Patient discomfort limits NMES muscle forces, potentially compromising efficacy.ObjectiveThe purpose of this study was to compare the NMES muscle torques produced by stimulation trains consisting of 2 different pulse durations.DesignDuring a single testing session, the 2 pulse duration conditions (50 and 200 microseconds) were tested on the opposite lower extremities of the participants.MethodsThe study participants were 10 adults without remarkable medical histories. The maximum tolerated isometric knee extensor torque was the primary dependent variable. The peak currents and phase charges that produced the maximally tolerated torques, as well as the sensory, motor, and pain thresholds for the 2 pulse conditions, were compared.ResultsThe 200-microsecond pulse duration condition resulted in participants tolerating significantly greater muscle torques; it was associated with significantly greater phase charges but significantly lower peak currents.LimitationsThis study only compared muscle torques in response to stimulation trains consisting of pulses with short (50-microsecond) or medium (200-microsecond) durations and did not examine long (∼400- to 600-microsecond) durations. Furthermore, the result of this study may not apply to NMES that uses stimulation patterns other than monophasic, square-wave pulsed current.ConclusionsIt has been suggested that short pulse durations are most appropriate for NMES because they are less likely to recruit nociceptors. The results of this study, however, support the use of a medium pulse duration rather than a short pulse duration when the goal is to produce a maximum torque response from a muscle. These observations may be related to the currents and phase charges for the pain thresholds for the 2 pulse duration conditions.

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