scholarly journals Impact Analysis of the Atmosphere Optical State on Wind Lidar Sounding Range

2020 ◽  
pp. 30-43
Author(s):  
M. L. Belov ◽  
A. A. Samsonova ◽  
S. E. Ivanov ◽  
V. A. Gorodnichev
Keyword(s):  
Pulse Energy ◽  
Impact Analysis ◽  
Attenuation Factor ◽  
Laser Source ◽  
Threshold Power ◽  
Energy Calculation ◽  
Signal Power ◽  
Lidar Sounding ◽  
Laser Signal ◽  
Detector Threshold

One of the most important questions for correlation lidars is the sounding range question.Correlation lidar sounding range greatly depends not only on the parameters of the equipment, but also on the optical state of the earth's atmosphere.In addition, there are currently two approaches to the estimation of lidar sounding range. In one approach, an estimate of the sounding range is obtained by equating the detector threshold power to the laser signal power recorded by the detector. In another approach, an estimate of the sounding range is obtained by equating the minimum detectable energy of the detected laser signal energy.This paper is about impact research of the atmosphere optical state on wind correlation lidar sounding range and compare sounding range estimates obtained under the two different approaches to the energy calculation lidar.The analysis is carried out for the surface layer of the atmosphere, the horizontal sounding path and the radiation wavelength of 0.532 μm. In atmospheric haze conditions, an empirical formula is used for the attenuation factor. The signal-to-noise ratio is assumed to be 100.Solid-state Nd:YAG Ekspla lasers NL319 (lamp pumping, pulse energy 5 J) and NL231-100 (diode pumping, pulse energy 90 mJ) were chosen as radiation sources.Hamamatsu photomultiplier tube R5070A with radiant sensitivity ~ 50 mA/W was chosen as a detector.It is shown that in a wide optical state range (meteorological range of visibility from 20 to 2 km) the lamp-pumped laser source sounding range with pulse energy 5 J varies from ~ 3,8 km to ~ 1,2 km and the diode-pumped laser source sounding range with pulse energy 90 mJ varies from ~ 1,1 km to ~ 0,64 km.The approach based on comparison of the detector threshold power with the received laser signal power overestimates the sounding range due to incomplete influencing consideration factors.

scholarly journals Effects of the Coupling between the Orbital Angular Momentum and the Temporal Degrees of Freedom in the Most Intense Ring of Ultrafast Vortices

2020 ◽  
Vol 10 (6) ◽  
pp. 1957 ◽  
Author(s):  
Miguel A. Porras
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Pulse Energy ◽  
Topological Charge ◽  
Degrees Of Freedom ◽  
Maximum Energy ◽  
Laser Source ◽  
Source Spectrum ◽  
Vortex Center ◽  
Peak Intensity

It has recently been shown that the temporal and the orbital angular momentum (OAM) degrees of freedom in ultrafast (few-cycle) vortices are coupled. This coupling manifests itself with different effects in different parts of the vortex, as has been shown for the ring surrounding the vortex where the pulse energy is maximum, and also in the immediate vicinity of the vortex center. However, in many applications, the ring of maximum energy is not of primary interest, but the one where the peak intensity of the pulse is maximum, which is particularly true in nonlinear optics applications such as experiments with ultrafast vortices that excite high harmonics and attosecond pulses that also carry OAM. In this paper, the effects of the OAM-temporal coupling on the ring of maximum pulse peak intensity, which do not always coincide with the ring of maximum pulse energy, are described. We find that there is an upper limit to the magnitude of the topological charge that an ultrafast vortex with a prescribed pulse shape in its most intense ring can carry, and vice versa, a lower limit to the pulse duration in the most intense ring for a given magnitude of the topological charge. These limits imply that, with a given laser source spectrum, the duration of the synthesized ultrafast vortex increases with the magnitude of the topological charge. Explicit analytical expressions are given for the ultrafast vortices that contain these OAM-temporal couplings effects, which may be of interest in various applications, in particular in the study of their propagation and interaction with matter.

scholarly journals High-pulse-energy mid-infrared laser source based on optical parametric amplification in ZnGeP_2

2008 ◽  
Vol 16 (18) ◽  
pp. 14263 ◽  
Author(s):  
Magnus W. Haakestad ◽  
Gunnar Arisholm ◽  
Espen Lippert ◽  
Stephane Nicolas ◽  
Gunnar Rustad ◽  
...  
Keyword(s):  
Pulse Energy ◽  
Infrared Laser ◽  
Parametric Amplification ◽  
Laser Source ◽  
Optical Parametric Amplification ◽  
High Pulse Energy ◽  
Mid Infrared ◽  
Optical Parametric ◽  
High Pulse

200W average power 1mJ pulse energy from spectrally combined pulsed sub-5 ns fiber laser source

2009 ◽  
Author(s):  
O. Schmidt ◽  
B. Ortac ◽  
J. Limpert ◽  
A. Tünnermann ◽  
Thomas V. Andersen
Keyword(s):  
Fiber Laser ◽  
Pulse Energy ◽  
Average Power ◽  
Laser Source

Compact ps-pulse laser source with free adjustable repetition rate and nJ pulse energy on microbench

2011 ◽  
Author(s):  
A. Klehr ◽  
A. Liero ◽  
Th. Hoffmann ◽  
S. Schwertfeger ◽  
H. Wenzel ◽  
...  
Keyword(s):  
Pulse Laser ◽  
Pulse Energy ◽  
Repetition Rate ◽  
Laser Source

Relevant Geometric Features in the Percussion Laser Microdrilling of Different Alloys

Volume 3 ◽  
2004 ◽  
Author(s):  
Paola Bassani ◽  
Edoardo Capello ◽  
Enrico Gallus ◽  
Elisabetta Gariboldi ◽  
Luca Longoni ◽  
...  
Keyword(s):  
Process Parameters ◽  
Pulse Energy ◽  
Pulse Length ◽  
Pulse Frequency ◽  
Laser Drilling ◽  
Laser Source ◽  
Drilling Process ◽  
Geometric Features ◽  
Hole Shape ◽  
Laser Sources

In the recent decade the laser drilling process has continually attracted new interests and has found increasing applications in the industry. Nowadays the most common industrial laser sources for laser drilling are the solid state ones with pulse length of the order of milliseconds, even if nanosecond and femtosecond pulse sources can also be found in industrial applications. The latter, short and ultrashort laser sources, are very promising since they are expected to generate the hole directly by vaporisation, leaving the hole surfaces free of molten and resolified layer, as well as very low amount of spatter. This paper reports an experimental study on microhole laser machining and on influence of some process parameters on the hole shape. The laser source used in the study was a pulsed, diode pumped, Q-switched Nd:YAG laser. The materials investigated were four different alloys (AISI 304 stainless steel, cp titanium, CuZn35 brass and IN718 alloy), provided as 0.5 mm thick commercial sheets. Since an experimental approach has been here preferred, the performed experimental plan has been designed by the analysis of variance technique. The influence of material type, as well as laser process parameters, like pulse frequency and pulse energy, have been investigated. Relevant geometrical features, like top and bottom hole diameter, taper angle, top and bottom aspect ratio, have been measured and analysed. Moreover, the geometric features of the top spatter as well as the metallurgical characteristics of heat affected zone has been investigated. The results have shown that pulse energy strongly affects both geometric and metallurgical hole features. On the other hand, pulse frequency does not seem to influence the hole shape in all material. The presence of spatter and metallographic analysis confirmed the production of molten layers in all material mainly around the hole entrance.

scholarly journals High-pulse-energy multiphoton imaging of neurons and oligodendrocytes in deep murine brain with a fiber laser

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Michael J. Redlich ◽  
Brad Prall ◽  
Edesly Canto-Said ◽  
Yevgeniy Busarov ◽  
Lilit Shirinyan-Tuka ◽  
...  
Keyword(s):  
Fiber Laser ◽  
Pulse Energy ◽  
Fluorescent Proteins ◽  
Average Power ◽  
Intravital Imaging ◽  
Laser Source ◽  
High Pulse Energy ◽  
Ti:Sapphire Laser ◽  
High Pulse ◽  
Murine Brain

AbstractHere we demonstrate high-pulse-energy multiphoton microscopy (MPM) for intravital imaging of neurons and oligodendrocytes in the murine brain. Pulses with an order of magnitude higher energy (~ 10 nJ) were employed from a ytterbium doped fiber laser source at a 1-MHz repetition rate, as compared to the standard 80-MHz Ti:Sapphire laser. Intravital imaging was performed on mice expressing common fluorescent proteins, including green (GFP) and yellow fluorescent proteins (YFP), and TagRFPt. One fifth of the average power could be used for superior depths of MPM imaging, as compared to the Ti:Sapphire laser: A depth of ~ 860 µm was obtained by imaging the Thy1-YFP brain in vivo with 6.5 mW, and cortical myelin as deep as 400 µm ex vivo by intrinsic third-harmonic generation using 50 mW. The substantially higher pulse energy enables novel regimes of photophysics to be exploited for microscopic imaging. The limitation from higher order phototoxicity is also discussed.

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