Identification of Near-Field and Far-Field Using Confocal Microscopy Setup for Optical Sensing Applications
The presence of near-field indicates the existence of evanescent waves, which is one of the important requirements for the development of an optical sensor. This study was carried out to identify the presence of near-field and far-field as monochromatic light propagated through various structures an...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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Academy of Sciences Malaysia
2019-07-01
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| Series: | ASM Science Journal |
| Subjects: | |
| Online Access: | https://doi.org/10.32802/asmscj.2019.276 |
| _version_ | 1797900903884259328 |
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| author | Wan Maisarah Mukhtar Nor Zahirah Mohd Zulkifli Razman Mohd Halim |
| author_facet | Wan Maisarah Mukhtar Nor Zahirah Mohd Zulkifli Razman Mohd Halim |
| author_sort | Wan Maisarah Mukhtar |
| collection | DOAJ |
| description | The presence of near-field indicates the existence of evanescent waves, which is one of the important requirements for the development of an optical sensor. This study was carried out to identify the presence of near-field and far-field as monochromatic light propagated through various structures and sizes of apertures. The confocal microscopy setup consisted of He-Ne laser with 633nm of excitation wavelength, apertures (slits and numerous sizes of pinholes), objective lens, projected screen and silicon photodetector. The near-field and far-field were determined by calculating the Fresnel number, FN as assorted size and design of apertures were added in the setup. The presence of far-field was identified with the usage of slits (single slits and double slits) represented by the value of FN, which was less than 1(FN<<1). As the aperture was replaced with pinholes with diameters within 30μm and 1.2mm, the near-field was resulted (FN>>1). Value of FN became greater as distance x between lens and pinholes increased. We also discovered a significant finding where the field intensities I were decreased with increment of distance x for the near-field, and vice versa (far-field). By using an extrapolating technique, it was found that the near-field can be created by using pinhole with a diameter of a<1.46mm. In conclusion, the discovery of this work proves an excellence role of pinholes in confocal microscopy setup in creating the evanescent waves for optical sensing applications. |
| first_indexed | 2024-04-10T08:52:17Z |
| format | Article |
| id | doaj.art-5313917a8c5649d98cc46cff3440d9c2 |
| institution | Directory Open Access Journal |
| issn | 1823-6782 |
| language | English |
| last_indexed | 2024-04-10T08:52:17Z |
| publishDate | 2019-07-01 |
| publisher | Academy of Sciences Malaysia |
| record_format | Article |
| series | ASM Science Journal |
| spelling | doaj.art-5313917a8c5649d98cc46cff3440d9c22023-02-22T03:11:21ZengAcademy of Sciences MalaysiaASM Science Journal1823-67822019-07-01121810.32802/asmscj.2019.276276Identification of Near-Field and Far-Field Using Confocal Microscopy Setup for Optical Sensing ApplicationsWan Maisarah Mukhtar0Nor Zahirah Mohd Zulkifli1Razman Mohd Halim2Universiti Sains Islam MalaysiaUniversiti Sains Islam MalaysiaNational Metrology Institute of Malaysia (NMIM), SIRIM BerhadThe presence of near-field indicates the existence of evanescent waves, which is one of the important requirements for the development of an optical sensor. This study was carried out to identify the presence of near-field and far-field as monochromatic light propagated through various structures and sizes of apertures. The confocal microscopy setup consisted of He-Ne laser with 633nm of excitation wavelength, apertures (slits and numerous sizes of pinholes), objective lens, projected screen and silicon photodetector. The near-field and far-field were determined by calculating the Fresnel number, FN as assorted size and design of apertures were added in the setup. The presence of far-field was identified with the usage of slits (single slits and double slits) represented by the value of FN, which was less than 1(FN<<1). As the aperture was replaced with pinholes with diameters within 30μm and 1.2mm, the near-field was resulted (FN>>1). Value of FN became greater as distance x between lens and pinholes increased. We also discovered a significant finding where the field intensities I were decreased with increment of distance x for the near-field, and vice versa (far-field). By using an extrapolating technique, it was found that the near-field can be created by using pinhole with a diameter of a<1.46mm. In conclusion, the discovery of this work proves an excellence role of pinholes in confocal microscopy setup in creating the evanescent waves for optical sensing applications.https://doi.org/10.32802/asmscj.2019.276near-fieldfar-fieldpinholesfresnel numberevanescent wave |
| spellingShingle | Wan Maisarah Mukhtar Nor Zahirah Mohd Zulkifli Razman Mohd Halim Identification of Near-Field and Far-Field Using Confocal Microscopy Setup for Optical Sensing Applications ASM Science Journal near-field far-field pinholes fresnel number evanescent wave |
| title | Identification of Near-Field and Far-Field Using Confocal Microscopy Setup for Optical Sensing Applications |
| title_full | Identification of Near-Field and Far-Field Using Confocal Microscopy Setup for Optical Sensing Applications |
| title_fullStr | Identification of Near-Field and Far-Field Using Confocal Microscopy Setup for Optical Sensing Applications |
| title_full_unstemmed | Identification of Near-Field and Far-Field Using Confocal Microscopy Setup for Optical Sensing Applications |
| title_short | Identification of Near-Field and Far-Field Using Confocal Microscopy Setup for Optical Sensing Applications |
| title_sort | identification of near field and far field using confocal microscopy setup for optical sensing applications |
| topic | near-field far-field pinholes fresnel number evanescent wave |
| url | https://doi.org/10.32802/asmscj.2019.276 |
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