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140 GHz Ultra-Long Bessel–Like Beam with Near-Wavelength Beamwidth

The Bessel–Gauss beam has outstanding features, such as long depth of focus (DOF) and super resolution for nondestructive imaging inspection. However, most approaches for generating a nondiffractive beam have mainly focused on extending the DOF. In this study, the ultra-long high-resolution Bessel–l...

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Autores principales: Ok, Gyeongsik, Park, Kee Jai
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7730688/
https://www.ncbi.nlm.nih.gov/pubmed/33261105
http://dx.doi.org/10.3390/s20236791
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author Ok, Gyeongsik
Park, Kee Jai
author_facet Ok, Gyeongsik
Park, Kee Jai
author_sort Ok, Gyeongsik
collection PubMed
description The Bessel–Gauss beam has outstanding features, such as long depth of focus (DOF) and super resolution for nondestructive imaging inspection. However, most approaches for generating a nondiffractive beam have mainly focused on extending the DOF. In this study, the ultra-long high-resolution Bessel–like beam was first demonstrated in a sub-THz wave range (140 GHz). An axicon lens having an apex angle of 110° was used to generate the highly focused Bessel–like beam. To extend the depth of focus, we varied the incident beam angle on the axicon by moving the first lens distance. With the newly developed beam profiler, 3D beam profiles were acquired for characterizing in detail the beam propagation. As a result, even if the depth of focus was 72 times (154 mm) the source wavelength (2.143 mm), the focusing beamwidth was simultaneously maintained at 1.4 times (3.0 mm) the wavelength (i.e., the near-wavelength beamwidth). An ultra-long needle beam of near-wavelength size can promote the applicability of the sub-THz imaging technique in noninvasive sensing applications, such as computer tomography, materials inspection, and through-the-wall-imaging.
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spelling pubmed-77306882020-12-12 140 GHz Ultra-Long Bessel–Like Beam with Near-Wavelength Beamwidth Ok, Gyeongsik Park, Kee Jai Sensors (Basel) Letter The Bessel–Gauss beam has outstanding features, such as long depth of focus (DOF) and super resolution for nondestructive imaging inspection. However, most approaches for generating a nondiffractive beam have mainly focused on extending the DOF. In this study, the ultra-long high-resolution Bessel–like beam was first demonstrated in a sub-THz wave range (140 GHz). An axicon lens having an apex angle of 110° was used to generate the highly focused Bessel–like beam. To extend the depth of focus, we varied the incident beam angle on the axicon by moving the first lens distance. With the newly developed beam profiler, 3D beam profiles were acquired for characterizing in detail the beam propagation. As a result, even if the depth of focus was 72 times (154 mm) the source wavelength (2.143 mm), the focusing beamwidth was simultaneously maintained at 1.4 times (3.0 mm) the wavelength (i.e., the near-wavelength beamwidth). An ultra-long needle beam of near-wavelength size can promote the applicability of the sub-THz imaging technique in noninvasive sensing applications, such as computer tomography, materials inspection, and through-the-wall-imaging. MDPI 2020-11-27 /pmc/articles/PMC7730688/ /pubmed/33261105 http://dx.doi.org/10.3390/s20236791 Text en © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Letter
Ok, Gyeongsik
Park, Kee Jai
140 GHz Ultra-Long Bessel–Like Beam with Near-Wavelength Beamwidth
title 140 GHz Ultra-Long Bessel–Like Beam with Near-Wavelength Beamwidth
title_full 140 GHz Ultra-Long Bessel–Like Beam with Near-Wavelength Beamwidth
title_fullStr 140 GHz Ultra-Long Bessel–Like Beam with Near-Wavelength Beamwidth
title_full_unstemmed 140 GHz Ultra-Long Bessel–Like Beam with Near-Wavelength Beamwidth
title_short 140 GHz Ultra-Long Bessel–Like Beam with Near-Wavelength Beamwidth
title_sort 140 ghz ultra-long bessel–like beam with near-wavelength beamwidth
topic Letter
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7730688/
https://www.ncbi.nlm.nih.gov/pubmed/33261105
http://dx.doi.org/10.3390/s20236791
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