Internal and near‐surface electromagnetic fields for a spherical particle irradiated by a focused laser beam

1988 ◽  
Vol 64 (4) ◽  
pp. 1632-1639 ◽  
Author(s):  
J. P. Barton ◽  
D. R. Alexander ◽  
S. A. Schaub
Keyword(s):  
Laser Beam ◽  
Spherical Particle ◽  
Electromagnetic Fields ◽  
Near Surface

Forward Scattering Signature of a Spherical Particle Crossing a Laser Beam out of the Beam Waist

1988 ◽  
Vol 5 (1) ◽  
pp. 9-12 ◽  
Author(s):  
Jean-Philippe Chevaillier ◽  
Jean Fabre ◽  
Patrice Hamelin ◽  
Jean-Loup Lense
Keyword(s):  
Laser Beam ◽  
Spherical Particle ◽  
Beam Waist ◽  
Forward Scattering

scholarly journals Internal and near-surface electromagnetic fields for a chiral cylinder with arbitrary monochromatic illumination

Optik ◽  
2019 ◽  
Vol 178 ◽  
pp. 1337-1341 ◽  
Author(s):  
Bing Yan ◽  
Huayong Zhang ◽  
Jianyong Zhang ◽  
Renxian Li
Keyword(s):  
Electromagnetic Fields ◽  
Near Surface ◽  
Monochromatic Illumination

Absolute Magnetometry Using Electron Holography: Magnetic Superlattices and Small Particles

MRS Bulletin ◽  
1995 ◽  
Vol 20 (10) ◽  
pp. 45-48 ◽  
Author(s):  
Marian Mankos ◽  
J.M. Cowley ◽  
M.R. Scheinfein
Keyword(s):  
Electromagnetic Fields ◽  
Spatial Resolution ◽  
Giant Magnetoresistance ◽  
High Spatial Resolution ◽  
Imaging Techniques ◽  
Absolute Calibration ◽  
Magnetization Distribution ◽  
Electron Holography ◽  
Near Surface ◽  
Magnetic Microstructure

Synthesized magnetic structures are of interest due to their unique and unusual properties, which are governed by their micromagnetic structure. For example, giant-magnetoresistance (GMR) multilayer structures composed of magnetic layers separated by nonmagnetic spacers, and granular GMR films composed of magnetic and nonmagnetic metals exhibit phenomena whose interpretation requires knowledge of both the physical and micromagnetic structure at nanometer-length scales. Techniques for magnetic-microstructure imaging are based on the interaction between a probe and either the magnetic microstructure itself (magnetization) or a physical quantity related to the magnetization distribution (e.g., magnetostriction, magnetic induction). Transmission methods are sensitive to bulk magnetic microstructure averaged along the direction of the incident probe; surface structure is lost. Reflection techniques interact with the near-surface region and no information is obtained about the bulk structure aside from those properties that can be inferred from appropriate boundary conditions.Electron-optical methods represent the widest class of high-spatial-resolution, magnetic-domain imaging techniques. The most advanced techniques provide the highest contrast, sensitivity, and point resolution (1 nm). Electron holography offers quantitative micromagnetic information at high spatial resolution, a feature missing in most magnetic-imaging techniques. Quantitative information can be extracted from the absolutely calibrated electron wavelength and a knowledge of electron phase shifts in electromagnetic fields. High sensitivity, nanometer spatial resolution, and absolute calibration make electron holography a powerful tool for examining magnetic microstructure. In electron holography, both the amplitude and phase of the transmitted electron waves can be recovered in contrast to conventional electron microscopy where only the intensity is available. The phase, containing information about the local distribution of electromagnetic fields, can be retrieved from an electron hologram.

Prozessüberwachung beim Laser-Strahlschmelzen mit akustischen Signalen*/Monitoring a laser beam melting process with acoustic signals

2017 ◽  
Vol 107 (11-12) ◽  
pp. 818-823
Author(s):  
N. Eschner ◽  
J. Lingenhöhl ◽  
S. Öppling ◽  
G. Prof. Lanza
Keyword(s):  
Laser Beam ◽  
Acoustic Waves ◽  
Ultrasonic Inspection ◽  
Melting Process ◽  
Acoustic Signals ◽  
Inspection System ◽  
Near Surface ◽  
Surface Areas ◽  
Melt Pool ◽  
Laser Beam Melting

Gegenwärtig ist bei der additiven Fertigung eine prozessbegleitende Überwachung des Bauteils auf das Schmelzbad und oberflächennahe Bereiche limitiert. Mithilfe akustischer Signale lassen sich typische Defekte, die im Rahmen des LBM (laser beam melting – Laserstrahlschmelzen)-Verfahrens auftreten, detektieren. Dies umfasst neben Porosität und Rissen auch Eigenspannungen. In diesem Fachbeitrag werden die Möglichkeit eines in den LBM-Prozess integrierten akustischen Prüfsystems sowie alternative Sensorkonzepte diskutiert und evaluiert.   Current process monitoring techniques for additive manufacturing are limited to the melt pool and near-surface areas. Typical defects that occur within the LBM-process, such as porosity and cracks, as well as residual stress, can be detected by using acoustic waves. In this article, the possibility of an integrated ultrasonic inspection system, as well as various sensor concepts are discussed and evaluated.

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