Application of two-color pyrometer for studying of flying luminous particles: Products of alumina laser ablation

The design of a two-color pyrometer is described, allowing not only measurement of the temperature of a single flying luminous particle with sizes from submicron to millimeters but also the 3D reconstruction of its flight trajectory, the determination of its real velocity, size, frequencies of oscil...

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Bibliographic Details
Published in:Review of scientific instruments 2019-04, Vol.90 (4), p.043904-043904
Main Authors: Larichev, Mikhail N., Belyaev, Grigori E., Stepanov, Ilya G., Velichko, Alexander M.
Format: Article
Language:English
Subjects:
Aluminum oxide
Color
Laser ablation
Lasers
Luminosity
Oscillations
Pulsed lasers
Scientific apparatus & instruments
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Summary:The design of a two-color pyrometer is described, allowing not only measurement of the temperature of a single flying luminous particle with sizes from submicron to millimeters but also the 3D reconstruction of its flight trajectory, the determination of its real velocity, size, frequencies of oscillations of its radiation intensities, and the type of the particle. A distinctive feature of the pyrometer is that two photographs of the flying particle (each in its own spectral band) used for the measurement of particle temperature are made from two mutually perpendicular directions. This device was used to investigate individual condensed particles emitted from the crater by the pulsed laser ablation of alumina. It was found that among the particles the micron and submicron drops are observed as well as the hollow bubbles with diameters up to several millimeters; the drops formed from the boiling and supercooled melt of Al2O3 can be ejected practically at the same time during the laser pulse. The digital processing of the particle streaks has shown that the luminosity of most of the observed particles is isotropic, although the particles radiating nonisotropically are also observed. The radiation of both types of particles may be oscillating. Surprisingly, frequencies of oscillations of the radiation intensity of the flying particle may differ for two channels of the pyrometer registration. The obtained results can be useful to characterize the phase state, properties of alumina particles, and specific features of relaxation of overheated alumina melt. They are interesting both for basic and applied science.
ISSN:0034-6748
1089-7623
DOI:10.1063/1.5063447