scholarly journals The Influence of the Processing Parameters on the Laser-Ablation of Stainless Steel and Brass during the Engraving by Nanosecond Fiber Laser

Nanomaterials ◽  
2022 ◽  
Vol 12 (2) ◽  
pp. 232
Author(s):  
Luka Hribar ◽  
Peter Gregorčič ◽  
Matej Senegačnik ◽  
Matija Jezeršek
Keyword(s):  
Surface Roughness ◽  
Fiber Laser ◽  
Pulse Duration ◽  
Repetition Rate ◽  
Pulse Repetition Rate ◽  
Removal Rate ◽  
Average Power ◽  
Laser Pulses ◽  
Processing Parameters ◽  
Pulse Repetition

In this paper, we investigate the influence of the following parameters: pulse duration, pulse repetition rate, line-to-line and pulse-to-pulse overlaps, and scanning strategy on the ablation of AISI 316L steel and CuZn37 brass with a nanosecond, 1064-nm, Yb fiber laser. The results show that the material removal rate (MRR) increases monotonically with pulse duration up to the characteristic repetition rate (f0) where pulse energy and average power are maximal. The maximum MRR is reached at a repetition rate that is equal or slightly higher as f0. The exact value depends on the correlation between the fluence of the laser pulses and the pulse repetition rate, as well as on the material properties of the sample. The results show that shielding of the laser beam by plasma and ejected material plays an important role in reducing the MRR. The surface roughness is mainly influenced by the line-to-line and the pulse-to-pulse overlaps, where larger overlap leads to lower roughness. Process optimization indicates that while operating with laser processing parameters resulting in the highest MRR, the best ratio between the MRR and surface roughness appears at ~50% overlap of the laser pulses, regardless of the material being processed.

In vitro study of cataract extraction by bursts of microsecond 1.54-mm laser pulses

2022 ◽  
Vol 52 (1) ◽  
pp. 69-77
Author(s):  
A V Belikov ◽  
S N Smirnov ◽  
Yu N Batov ◽  
A B Gubin ◽  
Yu B Pirozhkov ◽  
...  
Keyword(s):  
Repetition Rate ◽  
Pulse Repetition Rate ◽  
Video Recording ◽  
Average Power ◽  
Cataract Extraction ◽  
Pulse Repetition ◽  
Glass Laser ◽  
First Time ◽  
Pulse Spacing

Abstract Laser extraction of a model porcine eye cataract has been performed for the first time in an in vitro experiment using a 1.54-μm Yb,Er : glass laser generating bursts of microsecond pulses. We used effective pulse repetition rates from 36 to 75 Hz and average laser output powers from 3.9 to 5.25 W. The results demonstrate for the first time that, at an effective pulse repetition rate of 45 Hz, burst repetition rate of 15 Hz, three microsecond pulses per burst, and a burst energy from 260 to 265 mJ, the laser step duration in cataract extraction is 130 plusmn; 10 s, which is comparable to the ultrasonic phacoemulsification and laser extraction time in the case of a Nd : YAG laser emitting at 1.44 μm. Acoustometry and high speed video recording of hydroacoustic processes accompanying interaction of water with 1.54-μm radiation from the Yb, Er : glass laser generating bursts of microsecond pulses have made it possible for the first time to detect overlap of hydroacoustic processes at the pulse spacing in bursts reduced to under 700 μs. In the case of overlap of hydroacoustic processes, despite the increase in average power and effective pulse repetition rate, acoustic wave generation is ineffective because pulses propagate through bubbles formed in the water. Laser cataract extraction is shown to be most effective at a lower average power, lower effective pulse repetition rate, and burst pulse spacing of 850 ± 10 μs.

Pulse-repetition-rate tuning of a harmonically mode-locked fiber laser using a tapered photonic crystal fiber

2019 ◽  
Vol 44 (7) ◽  
pp. 1580 ◽  
Author(s):  
Dung-Han Yeh ◽  
Wenbin He ◽  
Meng Pang ◽  
Xin Jiang ◽  
Gordon Wong ◽  
...  
Keyword(s):  
Photonic Crystal ◽  
Fiber Laser ◽  
Photonic Crystal Fiber ◽  
Repetition Rate ◽  
Pulse Repetition Rate ◽  
Pulse Repetition ◽  
Crystal Fiber

Physico-Mechanical Properties of the Cr-C and Mo-C Coatings

2013 ◽  
Vol 750-752 ◽  
pp. 1959-1962
Author(s):  
Е.A. Stepanova ◽  
I.L. Pobol ◽  
J. Rajczyk
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Repetition Rate ◽  
Pulse Repetition Rate ◽  
Arc Discharge ◽  
Plasma Source ◽  
Pulse Repetition ◽  
Vacuum Arc ◽  
The Coefficient Of Friction ◽  
The Individual

The investigation of physico-mechanical properties of metal-carbon (Cr-C and Mo-C) coatings obtained using pulsed vacuum arc deposition has been carried out. Changing the arc discharge pulse repetition rate of the individual plasma sources equipped with metal and graphite cathodes allows significant varying of the composition, surface roughness and friction coefficient of the coatings. When reducing the pulse repetition rate in metal plasma source from 10 Hz to 5 Hz while retaining that constant in carbon source, the metal content in the coating can be decreased from 30 at.% to 2 at. % with increasing the surface roughness by a factor of 3.5. The tribological investigations of Cr-C and Mo-C coatings under the dry friction conditions showed the uniform adhesive wear of the coating upper layers. The coefficient of friction measured against steel counterbody was in the range of 0.08 to 0.1. However, in this case Mo-C coatings were more wear-resistant than Cr-C coatings.

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