scholarly journals In Search of Optimal Laser Settings for Lithotripsy by Numerical Response Surfaces of Ablation and Retropulsion

2021 ◽  
Author(s):  
Jian J. Zhang
Keyword(s):  
Laser Pulse ◽  
Response Surface ◽  
Pulse Energy ◽  
Pulse Width ◽  
Peak Power ◽  
Laser System ◽  
Operation Time ◽  
Laser Lithotripsy ◽  
Yag Laser ◽  
Impact Coefficient

Even though ureteroscopic laser lithotripsy (URSL) has become the preferred treatment option for urolithiasis due to shorter operation time and a better stone-free rate, the optimum laser pulse settings for URSL with the shortest operative times remain unknown. In this chapter, two sets of design of experiments (DOE) were conducted with response surface methodology: 1) the quantitative responses of calculus ablation and retropulsion in terms of the pulse energy, pulse width, and the number of pulses of a prototype Chromium (Cr3+), Thulium (Tm3+), Holmium (Ho3+) triple doped yttrium aluminum garnet (CTH:YAG) laser system. The ablation or retropulsion is inversely proportional to the pulse width, and the pulse width has a higher impact coefficient for the ablation than for the retropulsion. The quadratic fit of the response surface for the volume of ablation has a nonlinear relationship with the pulse width and number of pulses. 2) the laser setting optimization of laser lithotripsy of a commercially available CTH: YAG laser system. The experimental setup is based on a benchtop model first introduced by Sroka’s group. Comparing to frequency, the laser pulse energy or peak power has a higher impact coefficient to stone retropulsion as compared to stone ablation in CTH: YAG laser lithotripsy. The most efficient way to curtail stone retropulsion during laser lithotripsy is to lower the laser pulse peak power.

Study on Laser Welding of Phone Nuts

2013 ◽  
Vol 815 ◽  
pp. 778-781
Author(s):  
Xiao Hong Wu
Keyword(s):  
Tensile Strength ◽  
Stainless Steel ◽  
Laser Pulse ◽  
Laser Welding ◽  
Pulse Energy ◽  
Pulse Width ◽  
Peak Power ◽  
Laser Pulse Energy ◽  
304 Stainless Steel ◽  
Power Pulse

Used YAG pulse laser to weld 304 stainless steel nuts, studied about the parameters such as peak power, pulse width, defocus distance impacting on the performance of the joints welded by laser. The studies showed that the tensile strength and torque of the nuts increased as the peak power and the pulse width increased.Burn through in welding easy occur when laser pulse energy is too big, pulse width is too wide or defocus distance is too low.

scholarly journals Numerical Response Surfaces of Volume of Ablation and Retropulsion Amplitude by Settings of Ho:YAG Laser Lithotripter

2018 ◽  
Vol 2018 ◽  
pp. 1-11
Author(s):  
Jian J. Zhang ◽  
Jonathan Rutherford ◽  
Metasebya Solomon ◽  
Brian Cheng ◽  
Jason R. Xuan ◽  
...  
Keyword(s):  
Pulse Energy ◽  
Pulse Width ◽  
High Speed ◽  
Operation Time ◽  
Laser Lithotripsy ◽  
Pulse Number ◽  
Response Surfaces ◽  
Ho:Yag Laser ◽  
Energy Pulse ◽  
Best Fit

Objectives.Although laser lithotripsy is now the preferred treatment option for urolithiasis due to shorter operation time and a better stone-free rate, the optimal laser settings for URS (ureteroscopic lithotripsy) for less operation time remain unclear. The aim of this study was to look for quantitative responses of calculus ablation and retropulsion by performing operator-independent experiments to determine the best fit versus the pulse energy, pulse width, and the number of pulses.Methods.A lab-built Ho:YAG laser was used as the laser pulse source, with a pulse energy from 0.2 J up to 3.0 J and a pulse width of 150 μs up to 1000 μs. The retropulsion was monitored using a high-speed camera, and the laser-induced craters were evaluated with a 3-D digital microscope. The best fit to the experimental data is done by a design of experiment software.Results.The numerical formulas for the response surfaces of ablation speed and retropulsion amplitude are generated.Conclusions.The longer the pulse, the less the ablation or retropulsion, while the longer pulse makes the ablation decrease faster than the retropulsion. The best quadratic fit of the response surface for the volume of ablation varied nonlinearly with pulse duration and pulse number.

scholarly journals Prognostic Factors for the Outcome of Salivary Gland Holmium: YAG Laser Intraductal Lithotripsy

2021 ◽  
pp. 014556132110100
Author(s):  
Shuo-Jen Wang ◽  
Lung-Che Chen ◽  
Yi-Chih Lin ◽  
Yen-Chun Chen ◽  
Luong Huu Dang ◽  
...  
Keyword(s):  
Logistic Regression ◽  
Salivary Gland ◽  
Success Rate ◽  
Operative Time ◽  
Tertiary Care ◽  
Operation Time ◽  
Laser Lithotripsy ◽  
Successful Outcome ◽  
Care Hospital ◽  
Yag Laser

Objectives: Holmium: YAG laser has gained its popularity throughout the years and is used to treat sialolithiasis, which helps to overcome the limitations of traditional sialendoscopic lithotripsy for larger-sized salivary stones. However, little information is available regarding factors predicting the success rate of Holmium: YAG laser intraductal lithotripsy. The purpose of this study is to investigate the factors affecting the success rates of Holmium: YAG laser lithotripsy for salivary stones treatment in a tertiary care hospital. Methods: A retrospective study conducted in patients receiving sialolithiasis surgery under sialendoscopy from May 2013 to March 2015 at Mackay Memorial Hospital, Taiwan. Data on various factors, including patients’ age, gender, glands, size of largest stone, multiple stones (≥2 stones), location of the stone (distal duct, middle duct, proximal duct, and hilum), and operative time. The success of the surgery defined as patients without any complaints such as swelling or tenderness. Logistic regression and Fisher exact tests were employed to examine these factors on the success rate. Results: Fifty-four patients who received sialendoscopy surgery with a mean age of 35.74 years old recruited. Logistic regression identified the operation time exceeding 210 minutes showed 23.497 folds higher odd ratio of having a result of operation failure ( P < .05). Conclusion: The prolonged operation time is the sole independent factor affecting the successful outcome for salivary gland intraductal laser lithotripsy. We recommend operative time be no more than 210 minutes to increase the success rate in salivary gland Holmium: YAG laser intraductal lithotripsy.

scholarly journals All-fiber passively Q-switched ytterbium doped double-clad fiber lasers: experiment And modeling.

2021 ◽  
Author(s):  
Yi Lu
Keyword(s):  
Pulse Energy ◽  
Traveling Wave ◽  
Pulse Width ◽  
Fiber Lasers ◽  
Peak Power ◽  
Wave Model ◽  
Core Size ◽  
The Core ◽  
Q Switching ◽  
Output Characteristics

All-fiber passively Q-switched lasers were demonstrated using ytterbium-doped double cladding fiber (YDF) as an active medium. The laser was pumped by three 25W, 975nm fiber coupled diodes and Q-switching was initiated when the amplified spontaneous emission generated in the core of the gain fiber bleached the saturable absorber (SA). A piece of samarium-doped fiber was used as SA in first configuration and pulses with 68μJ pulse energy and 210ns pulse width were obtained. In second configuration, a piece of ytterbium-doped fiber with much smaller core size was used as SA to produce pulse energy of 86μJ. The last configuration incorporated a 9m-long YDF as gain fiber. The far end from pump was acting as SA in this case and pulses with 82μJ pulse energy and 148ns pulse width were observed. The peak power was estimated at 554W. Traveling wave model was implemented to numerically simulate the output characteristics versus pump power.

The study of laser pulse width on efficiency of Ho:YAG laser lithotripsy

2017 ◽  
Author(s):  
Jian J. Zhang ◽  
Jonathan Rutherford ◽  
Metasebya Solomon ◽  
Brian Cheng ◽  
Jason R. Xuan ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Pulse Width ◽  
Laser Lithotripsy ◽  
Ho:Yag Laser ◽  
Laser Pulse Width

A COMPACT EYE-SAFE OPO PUMPED BY A Nd:YAG MICROCHIP MOPA

2008 ◽  
Vol 18 (02) ◽  
pp. 483-492
Author(s):  
JIANWU DING ◽  
BRUCE W. ODOM ◽  
ALLEN R. GEIGER ◽  
RICHARD D. RICHMOND
Keyword(s):  
Power Amplifier ◽  
Pulse Energy ◽  
Optical Parametric Oscillator ◽  
Repetition Rate ◽  
Pulse Width ◽  
Peak Power ◽  
Parametric Oscillator ◽  
High Peak ◽  
High Peak Power ◽  
Optical Parametric

A compact high peak power eye-safer optical parametric oscillator was constructed by pumping it with a master oscillator power amplifier consisting of a large-mode-area ytterbium doped fiber amplifier and a diode-pumped, passively Q-switched Nd : YAG microchip laser. The master oscillator power amplifier has the maximum output pulse energy of 570 μJ with a 3 nanosecond pulse width and a 3 kHz pulse repetition rate. The compact singly resonating optical parametric oscillator utilized a 50 mm periodically poled Lithium Niobate crystal and generated high peak power 1.5 μm eye-safe laser pulses with more than 140 μJ pulse energy, 3 nanosecond pulse width and 3 kHz repetition rate.

Dependence of Charge Current Induced by Nd-YAG Laser Bombardment on Surrounding Gas Pressure and Laser Pulse Energy

2004 ◽  
Vol 43 (11A) ◽  
pp. 7524-7530 ◽  
Author(s):  
Marincan Pardede ◽  
Koo Hendrik Kurniawan ◽  
Tjung Jie Lie ◽  
May On Tjia ◽  
Yong Inn Lee ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Pulse Energy ◽  
Laser Pulse Energy ◽  
Gas Pressure ◽  
Yag Laser ◽  
Charge Current

scholarly journals Femtosecond Laser Machining At Submicron And Nano Scale

2021 ◽  
Author(s):  
Alireza Dalili
Keyword(s):  
Femtosecond Laser ◽  
Pulse Energy ◽  
Repetition Rate ◽  
Pulse Width ◽  
Laser System ◽  
High Repetition Rate ◽  
Silicon Wafers ◽  
Good Precision ◽  
High Repetition ◽  
Nano Scale

The arrival of the femtosecond laser with a MHz repetition rate has provided the industry with a new tool to conduct submicron and nano scale machining. Several advantages such as high quality machining finish, good precision and high throughput can be obtained when using femtosecond laser to conduct nanomachining over lithography techniques currently in use. High repetition rate systems are preferred over low repetition rate femtosecond laser systems that have been studied by others due to their increased stability, speed, quality and discovery of new phenomena such as ripples and grains. This thesis proposes a high repetition rate fiber femtosecond laser system for meeting the above-mentioned conditions. The influence of the laser repetition rate and pulse energy on the size and quality of nano features fabricated on silicon wafers was investigated. Higher repetition rates led to smaller cutlines with uniform width. A 110 nm crater with a small heat affected zone of 0.79 µm was obtained at 13 MHz repetition rate and 2.042 J/cm² energy fluence. In terms of nanomachining below the ablation threshold (surface patterning), the influence of pulse width, repetition rate and pulse energy on the spacing of ripples, as well as diameter of grains created on silicon wafers, was examined. For the pulse width, repetition rate and pulse energy range used, the ripple spacing and grain diameter increased with laser pulse duration while other parameters did not play a significant role. These results show the capability of the proposed system in meeting the industry requirements.

scholarly journals COPPER-BASED 3D PRINTER FILAMENT AS PASSIVE Q-SWITCHER

2021 ◽  
Vol 2075 (1) ◽  
pp. 012003
Author(s):  
N. N. A. A. N Zain ◽  
N. A. H. Jasni ◽  
W. M. F. W Nawawi ◽  
F. Ahmad
Keyword(s):  
Pulse Energy ◽  
Repetition Rate ◽  
Pulse Width ◽  
Peak Power ◽  
Fibre Laser ◽  
3D Printer ◽  
High Pulse Energy ◽  
Erbium Doped ◽  
High Pulse ◽  
Host Polymer

Abstract Using a copper-based saturable absorber (SA) and chitin as a biocompatible host polymer, this research effectively demonstrated the production of passive Q-switched in an erbium-doped fibre laser (EDFL). A Q-switched lasing was generated with a 100 kHz repetition rate and a pulse width of 4.60 µs. High pulse energy of 17.19 nJ was generated, with a respective instantaneous peak power of 3.51 mW.

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