scholarly journals LASER REFRACTOGRAPHY – A NOVEL TECHNOLOGY OF LIQUIDS REFRACTOMETRY

2019 ◽  
pp. 157-166
Author(s):  
I.L. Raskovskaya ◽  
B.S. Rinkevichyus ◽  
S.P. Yurkevichyus
Keyword(s):  
Measurement Technique ◽  
Fluid Flows ◽  
Computer Processing ◽  
Laser Beams ◽  
Digital Recording ◽  
Information Measurement ◽  
Novel Technology ◽  
Laser Systems ◽  
Inhomogeneous Liquids ◽  
Laser Refractography

This paper is devoted the base principles of the method of laser refractography and the results of its application in experimental visualization of optically inhomogeneous liquids. Laser refractography is a novel information-measurement technique based on the probing of fluid flows with a structured laser beams, digital recording of the refraction images obtained, and their computer processing with a view to reconstructing the parameters of the flows. Block diagrams of measuring laser systems are shown, and typical refracrograms are presented.

Computer Analysis of Electron Diffraction From thin Films

1998 ◽  
Vol 4 (S2) ◽  
pp. 344-345
Author(s):  
Warren MoberlyChan ◽  
R. Kilaas ◽  
L-H. Chan ◽  
T. Nolan ◽  
P. Dorsey ◽  
...  
Keyword(s):  
Thin Films ◽  
Electron Diffraction ◽  
Computer Processing ◽  
Information Storage ◽  
Engineering Properties ◽  
Digital Recording ◽  
Longitudinal Recording ◽  
Diffraction Patterns ◽  
User Friendly ◽  
Co Alloys

As engineering properties are miniaturized by mo thinner films, crystallographic analyses become more appropriate by electron diffraction than XRD. Without synchrotron sources, XRD scans of such films often expose one peak at best. However, these thinner films become more suited for TEM, with less artifacts from sample preparation. XRD scans with peaks in the noise are quantitatively accepted, while vast differences in electron diffraction patterns remain unquantified. Digital recording of TEM information removes the uncertain hand waving of the darkroom; and fast, user-friendly computer processing especially removes the nonstatistical art in image analysis. This work inputs 16-bit (>65,000 gray levels) images of ring diffraction patterns into Digital Micrograph and utilizes a Rotation Average subroutine (1) to plot peak intensities.Information storage in a hard drive utilizes sputtered thin films of HCP-Co-alloys with magnetic bits tied to the crystallographic orientation of each grain. Longitudinal-recording density and signal-to-noise can be enhanced for thin films with c-axes of all grains in plane.

scholarly journals New criteria for efficient Raman and Brillouin amplification of laser beams in plasma

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
R. M. G. M. Trines ◽  
E. P. Alves ◽  
E. Webb ◽  
J. Vieira ◽  
F. Fiúza ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Pulse Amplitude ◽  
Laser Beams ◽  
Seed Pulse ◽  
Coupling Constant ◽  
Minimum Threshold ◽  
The Poor ◽  
Laser Systems ◽  
Initial Seed ◽  
New Criteria

AbstractRaman or Brillouin amplification of a laser beam in plasma has long been seen as a way to reach multi-PW powers in compact laser systems. However, no significant plasma-based Raman amplification of a laser pulse beyond 0.1 TW has been achieved in nearly 20 years, and only one report of Brillouin amplification beyond 1 TW. In this paper, we reveal novel non-linear criteria for the initial seed pulse that will finally open the door to efficient Raman and Brillouin amplification to petawatt powers and Joule-level energies. We show that the triple product of the coupling constant $$\Gamma $$ Γ , seed pulse duration $$\tau $$ τ and seed pulse amplitude a for the Raman seed pulse (or $$a^{2/3}$$ a 2 / 3 for Brillouin) must exceed a specific minimum threshold for efficient amplification. We also analyze the plasma-based Raman and Brillouin amplification experiments to date, and show that the seed pulses used in nearly all experiments are well below our new threshold, which explains the poor efficiency obtained in them. Finally, we analyze a recent Brillouin amplification experiment that used increased seed pulse power to obtain Joule-level amplification, and find excellent agreement with our theory.

Digital Recording and Numerical Reconstruction of Holograms: A New Optical Diagnostic for Combustion

2002 ◽  
Author(s):  
Xudong Xiao ◽  
Ishwar K. Puri
Keyword(s):  
Numerical Method ◽  
Measurement Technique ◽  
Holographic Interferometry ◽  
Fourier Optics ◽  
Chemical Processing ◽  
Digital Recording ◽  
Real Time Processing ◽  
Time Processing ◽  
Numerical Reconstruction ◽  
Optical Diagnostic

Digital holographic interferometry (DHI) is a relatively newer imaging and measurement technique that electronically records a hologram (e.g., on a CCD) and reconstructs it using a numerical method. Cumbersome chemical processing of the hologram is avoided in DHI, thereby providing greater flexibility, speed, and the potential for real time processing. In conventional holography fringes that are neither bright nor dark on a hologram cannot be accurately resolved. The DHI technique reported so far has not yet been used for combustion applications. Herein, we will evaluate its efficacy for making temperature measurements in flames and assess its applicability through a simulation. The double exposures associated with the holographic technique are each considered recorded by a hypothetical CCD sensor at separate times. We have applied the principles of Fourier optics to develop a numerical method for hologram reconstruction.

Generation and control of intense laser beams in multibeam laser systems

1992 ◽  
Author(s):  
Fedor V. Lebedev ◽  
Alexander F. Glova ◽  
O. R. Kachurin ◽  
Anatoly P. Napartovich ◽  
Vladislav D. Pis'mennyi
Keyword(s):  
Intense Laser ◽  
Laser Beams ◽  
Laser Systems ◽  
And Control

The Seismic Research Observatory

1976 ◽  
Vol 66 (6) ◽  
pp. 2049-2068 ◽  
Author(s):  
Jon Peterson ◽  
Howell M. Butler ◽  
L. Gary Holcomb ◽  
Charles R. Hutt
Keyword(s):  
Seismic Data ◽  
Broad Band ◽  
Computer Processing ◽  
Preliminary Evaluation ◽  
Digital Recording ◽  
Digital Form ◽  
Data Resource ◽  
Long Period ◽  
Period Data ◽  
Mass Position

abstract Thirteen advanced seismograph systems, called Seismic Research Observatories (SRO), are being installed as part of a program to upgrade the worldwide seismic data network. The SRO system was created by combining a recently developed broad-band borehole seismometer and a software-controlled recording system. The seismometers are being installed at a depth of 100 meters to avoid wind-generated noise in the long-period band. A seismometer output that is flat in acceleration between periods of 1 and 50 sec is used to produce both short- and long-period data that are recorded on analog drum recorders and in digital form on magnetic tape. Very-long-period data, obtained from the seismometer mass position output, can be recorded as well. Digital recording of gain-ranged data provides an amplitude of nearly 120 dB. Preliminary evaluation of the SRO data system indicates that major design objectives have been met. The network of SRO stations will be an important new data resource for seismological investigations, especially for those studies that require computer processing of the data.

scholarly journals Laser beam welding setup for the coaxial combination of two laser beams to vary the intensity distribution

2022 ◽  
Author(s):  
M. Möbus ◽  
P. Woizeschke
Keyword(s):  
Laser Beam ◽  
Penetration Depth ◽  
Intensity Distribution ◽  
Laser Beam Welding ◽  
Sample Surface ◽  
Laser Beams ◽  
Deep Penetration ◽  
Focal Position ◽  
Laser Systems ◽  
Laser Sources

AbstractDeep-penetration laser beam welding is highly dynamic and affected by many parameters. Several investigations using differently sized laser spots, spot-in-spot laser systems, and multi-focus optics show that the intensity distribution is one of the most influential parameters; however, the targeted lateral and axial intensity design remains a major challenge. Therefore, a laser processing optic has been developed that coaxially combines two separate laser sources/beams with different beam characteristics and a measuring beam for optical coherence tomography (OCT). In comparison to current commercial spot-in-spot laser systems, this setup not only makes it possible to independently vary the powers of the two laser beams but also their focal planes, thus facilitating the investigation into the influence of specific energy densities along the beam axis. First investigations show that the weld penetration depth increases with increasing intensities in deeper focal positions until the reduced intensity at the sample surface, due to the deep focal position, is no longer sufficient to form a stable keyhole, causing the penetration depth to drop sharply.

Equipment for High-Pressure Infrared Measurements

1970 ◽  
Vol 24 (1) ◽  
pp. 21-27 ◽  
Author(s):  
C. S. Fang ◽  
J. V. Fox ◽  
C. E. Mauk ◽  
H. W. Prengle
Keyword(s):  
Experimental Data ◽  
High Pressure ◽  
Measurement Technique ◽  
Vibrational Frequency ◽  
Digital Voltmeter ◽  
Computer Processing ◽  
Frequency Shifts ◽  
Precise Positioning ◽  
Infrared Measurements ◽  
Grating Monochromator

Since vibrational frequency shifts in liquids, produced by solvents and/or high liquid densities, are relatively small, precision equipment and techniques must be used. Design and operation of modified equipment, including a long path grating monochromator, a pressuring system and cells for pressures up to 5000–10 000 atm are described. A static measurement technique, involving precise positioning of the grating and read out of the transmittance on a digital voltmeter, followed by computer processing of the series of points which describe the absorption peak to determine the v˜0, are also described. Experimental data on C=C vibration on cis-pentene-2 are presented to illustrate results.

Evaluation of single-electron movies of glutamine synthetase molecules

1983 ◽  
Vol 41 ◽  
pp. 280-281
Author(s):  
W. Kunath ◽  
E. Zeitler ◽  
M. Kessel
Keyword(s):  
Electron Microscope ◽  
Glutamine Synthetase ◽  
Electron Irradiation ◽  
Structural Damage ◽  
Structural Changes ◽  
Single Electron ◽  
Continuous Series ◽  
Digital Recording ◽  
Recording Device ◽  
Low Exposure

The features of digital recording of a continuous series (movie) of singleelectron TV frames are reported. The technique is used to investigate structural changes in negatively stained glutamine synthetase molecules (GS) during electron irradiation and, as an ultimate goal, to look for the molecules' “undamaged” structure, say, after a 1 e/Å2 dose.The TV frame of fig. la shows an image of 5 glutamine synthetase molecules exposed to 1/150 e/Å2. Every single electron is recorded as a unit signal in a 256 ×256 field. The extremely low exposure of a single TV frame as dictated by the single-electron recording device including the electron microscope requires accumulation of 150 TV frames into one frame (fig. lb) thus achieving a reasonable compromise between the conflicting aspects of exposure time per frame of 3 sec. vs. object drift of less than 1 Å, and exposure per frame of 1 e/Å2 vs. rate of structural damage.

Sign in / Sign up

Export Citation Format

Share Document