Comparison of Laser-Ceramic and Laser-Metal Material Processing

2000 ◽  
Author(s):  
G. Deng ◽  
M. H. Gordon ◽  
L. A. Roe ◽  
A. P. Malshe ◽  
W. F. Schmidt
Keyword(s):  
Early Stage ◽  
Laser Pulses ◽  
High Energy ◽  
Time Duration ◽  
Laser Ceramic ◽  
Metal Aluminum ◽  
Aluminum Plasma ◽  
Energy Laser ◽  
Gas Breakdown ◽  
Short Time

Abstract In an effort to better understand and thereby utilize laser processing, an existing code describing laser-metal (aluminum) interaction is modified to describe laser-ceramic (diamond) interaction. Comparisons between our modified code (diamond target) and the original code (aluminum target) highlight similarities and differences between laser-ceramic and laser-metal processing. Gas breakdown effects, which are expected for the simulated short (time duration), high energy laser pulses, are observed in both codes. Due to the lower sublimation heat of aluminum (1.1×104J/g) compared to diamond (5.3×104J/g), aluminum vaporizes more quickly and exhibits a faster expansion speed (1.4×107 cm/sec compared to 8×106 cm/sec for diamond) in the early stage of the laser pulse. Because aluminum requires significantly more energy to fully ionize than does carbon, our simulations show that the diamond plasma is fully ionized (6 of 6 electrons per atom) and the aluminum plasma is partially ionized (11 of 13 electrons per atom).

scholarly journals A quasi-monoenergetic short time duration compact proton source for probing high energy density states of matter

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
J. I. Apiñaniz ◽  
S. Malko ◽  
R. Fedosejevs ◽  
W. Cayzac ◽  
X. Vaisseau ◽  
...  
Keyword(s):  
Energy Density ◽  
Proton Beam ◽  
Dense Matter ◽  
High Energy ◽  
High Repetition Rate ◽  
High Energy Density ◽  
Time Duration ◽  
Ultrashort Pulse Laser ◽  
Proton Source ◽  
Short Time

AbstractWe report on the development of a highly directional, narrow energy band, short time duration proton beam operating at high repetition rate. The protons are generated with an ultrashort-pulse laser interacting with a solid target and converted to a pencil-like narrow-band beam using a compact magnet-based energy selector. We experimentally demonstrate the production of a proton beam with an energy of 500 keV and energy spread well below 10$$\% $$ % , and a pulse duration of 260 ps. The energy loss of this beam is measured in a 2 $$\upmu $$ μ m thick solid Mylar target and found to be in good agreement with the theoretical predictions. The short time duration of the proton pulse makes it particularly well suited for applications involving the probing of highly transient plasma states produced in laser-matter interaction experiments. This proton source is particularly relevant for measurements of the proton stopping power in high energy density plasmas and warm dense matter.

Optical fibre beam delivery of high-energy laser pulses: beam quality preservation and fibre end-preparation

2000 ◽  
Vol 34 (4-6) ◽  
pp. 273-288 ◽  
Author(s):  
A. Kuhn ◽  
I.J. Blewett ◽  
D.P. Hand ◽  
P. French ◽  
M. Richmond ◽  
...  
Keyword(s):  
Optical Fibre ◽  
Beam Quality ◽  
Laser Pulses ◽  
High Energy ◽  
Energy Laser ◽  
High Energy Laser ◽  
Beam Delivery

Experimental Investigation on Underwater Opto-Acoustic Communication

2011 ◽  
Vol 143-144 ◽  
pp. 653-657
Author(s):  
Tao Liu ◽  
Jian Gan Wang ◽  
Si Guang Zong
Keyword(s):  
Acoustic Communication ◽  
Acoustic Pressure ◽  
Optical Breakdown ◽  
Laser Pulses ◽  
Acoustic Signals ◽  
High Energy ◽  
Acoustic Energy ◽  
Underwater Sound ◽  
Energy Laser ◽  
High Energy Laser

The underwater opto-acoustic communication system for directional acoustic communication between an in-air platform and a submerged platform operating is important. The paper presents a new method to solve this problem with opto-acoustic technology, which combines high-energy laser, the opto-acoustic transmitter that optical energy is converted to acoustic energy at the water surface. The laser-based transmitter provides a versatile method for generating underwater sound. The acoustic pressure is linearly proportional to the laser power. The paper designed an experimental measurement system for the opto-acoustic communication. It made experiments for study on the waveform and spectrum characteristics of opto-acoustic signals. The paper also discuss the acoustic wave after optical breakdown in water with Nd:YAG laser pulses. The opto-acoustic signals can controll by adjusting the laser's parameters. The conclusion is that the opto-acoustic communication has some technical advantages. This system presents a change in the way communicational from the air.

Transparent laser damage resistant nematic liquid crystal cell “LCNP3”

2014 ◽  
Vol 22 (3) ◽  
Author(s):  
Z. Raszewski ◽  
W. Piecek ◽  
L. Jaroszewicz ◽  
R. Dąbrowski ◽  
E. Nowinowski-Kruszelnicki ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Nematic Liquid Crystal ◽  
Laser Pulses ◽  
High Energy ◽  
Optical Path ◽  
Liquid Crystal Cell ◽  
Crystal Cell ◽  
Energy Laser ◽  
High Energy Laser ◽  
Twisted Nematic Liquid Crystal

AbstractThere exists the problem in diagnostics of dense plasma (so-called Thomson diagnostics). For this purpose the plasma is illuminated by series of high energy laser pulses. The energy of each separate pulse is as large as 3 J, so it is impossible to generate a burst of such pulses by a single laser. In this situation, the pulses are generated by several independent lasers operating sequentially, and these pulses are to be directed along the same optical path. To form an optical path with λ = 1.064 μm and absolute value of the laser pulse energy of 3 J, a special refractive index matched twisted Nematic Liquid Crystal Cell of type LCNP3, with switching on time τON smaller than 3 μs was applied.

Compression of high-energy laser pulses below 5 fs

1997 ◽  
Vol 22 (8) ◽  
pp. 522 ◽  
Author(s):  
M. Nisoli ◽  
S. De Silvestri ◽  
O. Svelto ◽  
R. Szipöcs ◽  
K. Ferencz ◽  
...  
Keyword(s):  
Laser Pulses ◽  
High Energy ◽  
Energy Laser ◽  
High Energy Laser

Mechanical effects induced by shock waves generated by high energy laser pulses

1991 ◽  
Vol 1 (9) ◽  
pp. 1467-1480 ◽  
Author(s):  
J. Fournier ◽  
P. Ballard ◽  
P. Merrien ◽  
J. Barralis ◽  
L. Castex ◽  
...  
Keyword(s):  
Shock Waves ◽  
Laser Pulses ◽  
High Energy ◽  
Mechanical Effects ◽  
Energy Laser ◽  
High Energy Laser

Tapered metal-coated optical fibers for high-energy laser pulses delivery

1994 ◽  
Author(s):  
Alexander G. Papashvili ◽  
Vladimir A. Bogatyrjov ◽  
Konstantin M. Golant ◽  
Valery A. Kozlov ◽  
Alexander N. Perov ◽  
...  
Keyword(s):  
Optical Fibers ◽  
Laser Pulses ◽  
High Energy ◽  
Energy Laser ◽  
High Energy Laser

scholarly journals Long-Term Anatomic and Functional Outcomes after Macular Hole Surgery

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Karolina Kaźmierczak ◽  
Joanna Stafiej ◽  
Joanna Stachura ◽  
Paweł Żuchowski ◽  
Grażyna Malukiewicz
Keyword(s):  
Visual Acuity ◽  
Macular Hole ◽  
Functional Outcomes ◽  
Early Stage ◽  
Observation Time ◽  
Time Duration ◽  
Long Term Follow Up ◽  
Long Term Observation ◽  
Short Time

Aim. To evaluate the structural and functional outcomes in patients who underwent macular hole (MH) surgery in the long-term follow-up. Materials and Methods. Forty-four eyes of 40 patients (28 females and 12 males) were examined. The examination included visual acuity, optical coherence tomography, and colour vision testing. The same evaluation was performed in 30 fellow eyes. Results. MH closure was obtained in 42 eyes (95.45%). There was no reopening of the initially closed MHs. In long-term postoperative examination, we observed IS/OS junction defects in 28 (63.6%) eyes and ELM defects in 19 (43.2%) eyes. We found that the IS/OS junction defects correlated with the diameter of the MH (p=0.016), whereas ELM defects correlated with both the diameter of the MH (p=0.001) and duration time of the MH (p=0.008). The presence of ELM defects in OCT was the cause of inferior BCVA in long-term observation time (p=0.004). The mean BCVA before the MH surgery was 0.15. It improved significantly both in early (p<0.001) and long-term postoperative observation (p<0.005). Generally, the functional outcomes were better in eyes with short-time duration of the MH, when a smaller diameter (<400 μm) of the hole was measured and a V-shaped closure of the MH and the restoration of the ELM line on OCT were present. Pseudoprotanomaly was noted in 13 (35.1%) eyes. In the fellow eye group, mean BCVA was 0.95 (range, 0.6–1.0). In 3 eyes, we detected vitreomacular traction, and in 4 eyes, initial cataract. These conditions, as well as probably early stage of diabetes mellitus, influenced functional outcomes of studied eyes. Conclusions. The anatomic and functional outcomes after macular surgery are satisfactory and improve with time. After a successful closing of the MH, the restoration of the retina progresses at a slower pace than improvement in visual acuity.

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