Sharper Focal Spot for a Radially Polarized Beam Using Ring Aperture with Phase Jump
We study analytically and numerically in which way the width of ring aperture containing a phase jump affects the size and intensity of the focal spot generated with a radially polarized beam. It is shown that by means of destructive interference of beams coming from the different-phase rings it bec...
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| Format: | Article |
| Language: | English |
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Wiley
2013-01-01
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| Series: | Journal of Engineering |
| Online Access: | http://dx.doi.org/10.1155/2013/512971 |
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| author | Svetlana N. Khonina Andrei V. Ustinov |
| author_facet | Svetlana N. Khonina Andrei V. Ustinov |
| author_sort | Svetlana N. Khonina |
| collection | DOAJ |
| description | We study analytically and numerically in which way the width of ring aperture containing a phase jump affects the size and intensity of the focal spot generated with a radially polarized beam. It is shown that by means of destructive interference of beams coming from the different-phase rings it becomes possible to overcome the scalar diffraction limit corresponding to the first zero of the zero-order Bessel function. The minimal focal spot size (FWHM =0.33λ) is found to be attained when the annular aperture width amounts to 20% of the full-aperture radius. In this case, the side-lobe intensity is not larger than 30% of the central peak. A wider annular aperture with the phase jump introduced is also shown to form a focal spot not exceeding the diffraction limit for a narrow annular aperture, simultaneously providing a nearly six times higher intensity. In this case, the side lobes amount to 35% of the central peak. |
| format | Article |
| id | doaj-art-b5829f39234a4c7ba14f127f4e05b5b2 |
| institution | Kabale University |
| issn | 2314-4904 2314-4912 |
| language | English |
| publishDate | 2013-01-01 |
| publisher | Wiley |
| record_format | Article |
| series | Journal of Engineering |
| spelling | doaj-art-b5829f39234a4c7ba14f127f4e05b5b22025-02-03T00:59:50ZengWileyJournal of Engineering2314-49042314-49122013-01-01201310.1155/2013/512971512971Sharper Focal Spot for a Radially Polarized Beam Using Ring Aperture with Phase JumpSvetlana N. Khonina0Andrei V. Ustinov1Image Processing Systems Institute of the Russian Academy of Sciences, Molodogvardeiskaya Street 151, Samara 443001, RussiaImage Processing Systems Institute of the Russian Academy of Sciences, Molodogvardeiskaya Street 151, Samara 443001, RussiaWe study analytically and numerically in which way the width of ring aperture containing a phase jump affects the size and intensity of the focal spot generated with a radially polarized beam. It is shown that by means of destructive interference of beams coming from the different-phase rings it becomes possible to overcome the scalar diffraction limit corresponding to the first zero of the zero-order Bessel function. The minimal focal spot size (FWHM =0.33λ) is found to be attained when the annular aperture width amounts to 20% of the full-aperture radius. In this case, the side-lobe intensity is not larger than 30% of the central peak. A wider annular aperture with the phase jump introduced is also shown to form a focal spot not exceeding the diffraction limit for a narrow annular aperture, simultaneously providing a nearly six times higher intensity. In this case, the side lobes amount to 35% of the central peak.http://dx.doi.org/10.1155/2013/512971 |
| spellingShingle | Svetlana N. Khonina Andrei V. Ustinov Sharper Focal Spot for a Radially Polarized Beam Using Ring Aperture with Phase Jump Journal of Engineering |
| title | Sharper Focal Spot for a Radially Polarized Beam Using Ring Aperture with Phase Jump |
| title_full | Sharper Focal Spot for a Radially Polarized Beam Using Ring Aperture with Phase Jump |
| title_fullStr | Sharper Focal Spot for a Radially Polarized Beam Using Ring Aperture with Phase Jump |
| title_full_unstemmed | Sharper Focal Spot for a Radially Polarized Beam Using Ring Aperture with Phase Jump |
| title_short | Sharper Focal Spot for a Radially Polarized Beam Using Ring Aperture with Phase Jump |
| title_sort | sharper focal spot for a radially polarized beam using ring aperture with phase jump |
| url | http://dx.doi.org/10.1155/2013/512971 |
| work_keys_str_mv | AT svetlanankhonina sharperfocalspotforaradiallypolarizedbeamusingringaperturewithphasejump AT andreivustinov sharperfocalspotforaradiallypolarizedbeamusingringaperturewithphasejump |