scholarly journals Reflection of intense laser light from microstructured targets as a potential diagnostic of laser focus and plasma temperature

2018 ◽  
Vol 7 ◽  
Author(s):  
J. Jarrett ◽  
M. King ◽  
R. J. Gray ◽  
N. Neumann ◽  
L. Döhl ◽  
...  
Keyword(s):  
Focal Spot ◽  
Laser Light ◽  
Plasma Temperature ◽  
Regular Structure ◽  
Intense Laser ◽  
Reflected Light ◽  
Laser Focus ◽  
Speckle Patterns ◽  
Focal Spot Diameter ◽  
Laser Focal Spot

The spatial-intensity profile of light reflected during the interaction of an intense laser pulse with a microstructured target is investigated experimentally and the potential to apply this as a diagnostic of the interaction physics is explored numerically. Diffraction and speckle patterns are measured in the specularly reflected light in the cases of targets with regular groove and needle-like structures, respectively, highlighting the potential to use this as a diagnostic of the evolving plasma surface. It is shown, via ray-tracing and numerical modelling, that for a laser focal spot diameter smaller than the periodicity of the target structure, the reflected light patterns can potentially be used to diagnose the degree of plasma expansion, and by extension the local plasma temperature, at the focus of the intense laser light. The reflected patterns could also be used to diagnose the size of the laser focal spot during a high-intensity interaction when using a regular structure with known spacing.

scholarly journals Bremsstrahlung emission profile from intense laser-solid interactions as a function of laser focal spot size

2019 ◽  
Vol 61 (3) ◽  
pp. 034001 ◽  
Author(s):  
C D Armstrong ◽  
C M Brenner ◽  
E Zemaityte ◽  
G G Scott ◽  
D R Rusby ◽  
...  
Keyword(s):  
Focal Spot ◽  
Spot Size ◽  
Intense Laser ◽  
Focal Spot Size ◽  
Emission Profile ◽  
Bremsstrahlung Emission ◽  
Laser Focal Spot ◽  
Laser Solid Interactions

scholarly journals Passage of laser light through a hole-plasma shutter

1994 ◽  
Vol 12 (3) ◽  
pp. 445-454 ◽  
Author(s):  
K. Mašek ◽  
B. Králiková ◽  
J. Krása ◽  
L. Láska ◽  
K. Rohlena ◽  
...  
Keyword(s):  
Focal Spot ◽  
Laser Light ◽  
Laser Energy ◽  
Laser Pulses ◽  
Hole Diameter ◽  
Simple Analytical Model ◽  
Iodine Laser ◽  
Temporal Shape ◽  
Foil Target ◽  
Laser Focal Spot

The interaction of a plasma produced by irradiation of perforated foils with laser pulses was studied. The laser beam of the first harmonics of the iodine laser (λ = 1.315 μm) system PERUN was focused by anf/2 optics (f = 20 cm) on a hole in the foil target of high-Z material. The laser energy and the temporal shape of the pulses were monitored both before and behind the hole. Foils of two different materials (Pb, Cu) were used, and a series of hole diameters 2rH ranging from 100 μm to 500 μm were tested. The diameter of the laser focal spot 2r0 was about 150 μm. For hole diameters smaller than 300 μm, a shortening of the laser pulse was observed, demonstrating the effect of plasma shutter. The pulse shortening, which depends on the hole diameter, corresponds to the reduction in the pulse energy passing through the hole. An analysis of the experimental data is based on hydrodynamic computations, and the physics of the process is illustrated by a simple analytical model.

scholarly journals Laser-produced dense plasma in extremely high pressure gas and its application to a plasma-bridged gap switch

1989 ◽  
Vol 7 (3) ◽  
pp. 531-537 ◽  
Author(s):  
J. Yamada ◽  
T. Okuda
Keyword(s):  
High Pressure ◽  
Applied Voltage ◽  
High Velocity ◽  
Focal Spot ◽  
Laser Light ◽  
Switching Time ◽  
Dense Plasma ◽  
Intense Laser ◽  
Switching Characteristics ◽  
Focusing Lens

When an extremely high pressure gas is irradiated by an intense laser light, a dense plasma produced at the focal spot moves towards the focusing lens with a high velocity. Making use of this phenomenon, a new plasma-bridged gap switch is proposed and its switching characteristics is experimentally examined. From the experiments, it is confirmed that the switching time is almost constant with the applied voltage only when the focal spot is just on the positive electrode, indicating that the bridging of gap is caused by the laser light.

scholarly journals High-precision small-scale laser focal spot measurements

2013 ◽  
Vol 31 (1) ◽  
pp. 177-183 ◽  
Author(s):  
Z.W. Lu ◽  
X.Y. Liu ◽  
X. Wang ◽  
D.X. Ba ◽  
Z.H. Jiang ◽  
...  
Keyword(s):  
Background Noise ◽  
Measurement Accuracy ◽  
Focal Spot ◽  
Small Scale ◽  
Two Dimensional ◽  
Charge Coupled Device ◽  
Spot Diameter ◽  
Focal Spot Diameter ◽  
Laser Focal Spot ◽  
Better Than

AbstractIn this paper, a method of two-dimensional fine-scanning with charge coupled device has been conducted to precisely measure spatial position and intensity distribution of small-scale focal spot (diameter in microns). The measurement accuracy of the small-scale focal spot position is better than 1 µm when the fluctuations of the light energy and background noise are relatively small. The theoretical analysis is consistent with the experimental results.

XRMF applications of a monolithic, polycapillary, focusing x-ray optic

1996 ◽  
Vol 54 ◽  
pp. 240-241
Author(s):  
D. A. Carpenter ◽  
Ning Gao ◽  
G. J. Havrilla
Keyword(s):  
Trace Elements ◽  
Point Source ◽  
Focal Spot ◽  
Fluorescence Analysis ◽  
X Rays ◽  
Focal Distance ◽  
Spot Diameter ◽  
X Ray ◽  
Focal Spot Diameter

A monolithic, polycapillary, x-ray optic was adapted to a laboratory-based x-ray microprobe to evaluate the potential of the optic for x-ray micro fluorescence analysis. The polycapillary was capable of collecting x-rays over a 6 degree angle from a point source and focusing them to a spot approximately 40 µm diameter. The high intensities expected from this capillary should be useful for determining and mapping minor to trace elements in materials. Fig. 1 shows a sketch of the capillary with important dimensions.The microprobe had previously been used with straight and with tapered monocapillaries. Alignment of the monocapillaries with the focal spot was accomplished by electromagnetically scanning the focal spot over the beveled anode. With the polycapillary it was also necessary to manually adjust the distance between the focal spot and the polycapillary.The focal distance and focal spot diameter of the polycapillary were determined from a series of edge scans.

scholarly journals Dependence of laser accelerated protons on laser energy following the interaction of defocused, intense laser pulses with ultra-thin targets

2011 ◽  
Vol 29 (3) ◽  
pp. 345-351 ◽  
Author(s):  
C.M. Brenner ◽  
J.S. Green ◽  
A.P.L. Robinson ◽  
D.C. Carroll ◽  
B. Dromey ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Focal Spot ◽  
Laser Pulse Energy ◽  
Laser Energy ◽  
Spot Size ◽  
Proton Flux ◽  
Focal Spot Size ◽  
Order Of Magnitude ◽  
Laser Focal Spot ◽  
Accelerated Protons

AbstractThe scaling of the flux and maximum energy of laser-driven sheath-accelerated protons has been investigated as a function of laser pulse energy in the range of 15–380 mJ at intensities of 1016–1018 W/cm2. The pulse duration and target thickness were fixed at 40 fs and 25 nm, respectively, while the laser focal spot size and drive energy were varied. Our results indicate that while the maximum proton energy is dependent on the laser energy and laser spot diameter, the proton flux is primarily related to the laser pulse energy under the conditions studied here. Our measurements show that increasing the laser energy by an order of magnitude results in a more than 500-fold increase in the observed proton flux. Whereas, an order of magnitude increase in the laser intensity generated by decreasing the laser focal spot size, at constant laser energy, gives rise to less than a tenfold increase in observed proton flux.

scholarly journals Numerical simulation of a plasmonic lens for laser light focusing

2021 ◽  
Vol 2103 (1) ◽  
pp. 012174
Author(s):  
E S Kozlova ◽  
V V Kotlyar
Keyword(s):  
Focal Spot ◽  
Laser Light ◽  
Incident Light ◽  
Lens Design ◽  
Light Wavelength ◽  
Optimal Parameters ◽  
Plasmonic Lens ◽  
Radial Polarization ◽  
Incident Light Wavelength ◽  
Difference Time

Abstract In this paper, the design of a plasmonic lens in gold and silver thin films for focusing the light with radial polarization is presented. Using the finite difference time domain method the optimal parameters of the plasmonic lens design are found. It was shown that the silver plasmonic lens produces a tight focal spot with a full width at half maximum of 0.38 of the incident light wavelength.

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