Coherent Off-Axis Terahertz Tomography with a Multi-Channel Array and f-theta Optics
Terahertz tomography is a promising method among non-destructive inspection techniques to detect faults and defects in dielectric samples. Recently, image quality was improved significantly through the incorporation of <i>a priori</i> information and off-axis data. However, this improvem...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2024-01-01
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| Series: | Sensors |
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| Online Access: | https://www.mdpi.com/1424-8220/24/2/529 |
| _version_ | 1797339445771370496 |
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| author | Karl Henrik May Shiva Mohammadzadeh Andreas Keil Georg von Freymann Fabian Friederich |
| author_facet | Karl Henrik May Shiva Mohammadzadeh Andreas Keil Georg von Freymann Fabian Friederich |
| author_sort | Karl Henrik May |
| collection | DOAJ |
| description | Terahertz tomography is a promising method among non-destructive inspection techniques to detect faults and defects in dielectric samples. Recently, image quality was improved significantly through the incorporation of <i>a priori</i> information and off-axis data. However, this improvement has come at the cost of increased measurement time. To aim toward industrial applications, it is therefore necessary to speed up the measurement by parallelizing the data acquisition employing multi-channel setups. In this work, we present two tomographic frequency-modulated continuous wave (FMCW) systems working at a bandwidth of 230–320 GHz, equipped with an eight-channel detector array, and we compare their imaging results with those of a single-pixel setup. While in the first system the additional channels are used exclusively to detect radiation refracted by the sample, the second system features an f-θ lens, focusing the beam at different positions on its flat focal plane, and thus utilizing the whole detector array directly. The usage of the f-θ lens in combination with a scanning mirror eliminates the necessity of the formerly used slow translation of a single-pixel transmitter. This opens up the potential for a significant increase in acquisition speed, in our case by a factor of four to five, respectively. |
| first_indexed | 2024-03-08T09:47:11Z |
| format | Article |
| id | doaj.art-e87d320f4d064f09b8cfaafde07c634f |
| institution | Directory Open Access Journal |
| issn | 1424-8220 |
| language | English |
| last_indexed | 2024-03-08T09:47:11Z |
| publishDate | 2024-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Sensors |
| spelling | doaj.art-e87d320f4d064f09b8cfaafde07c634f2024-01-29T14:15:56ZengMDPI AGSensors1424-82202024-01-0124252910.3390/s24020529Coherent Off-Axis Terahertz Tomography with a Multi-Channel Array and f-theta OpticsKarl Henrik May0Shiva Mohammadzadeh1Andreas Keil2Georg von Freymann3Fabian Friederich4Fraunhofer Insititute for Industrial Mathematics ITWM, 67663 Kaiserslautern, GermanyFraunhofer Insititute for Industrial Mathematics ITWM, 67663 Kaiserslautern, GermanyFraunhofer Insititute for Industrial Mathematics ITWM, 67663 Kaiserslautern, GermanyFraunhofer Insititute for Industrial Mathematics ITWM, 67663 Kaiserslautern, GermanyFraunhofer Insititute for Industrial Mathematics ITWM, 67663 Kaiserslautern, GermanyTerahertz tomography is a promising method among non-destructive inspection techniques to detect faults and defects in dielectric samples. Recently, image quality was improved significantly through the incorporation of <i>a priori</i> information and off-axis data. However, this improvement has come at the cost of increased measurement time. To aim toward industrial applications, it is therefore necessary to speed up the measurement by parallelizing the data acquisition employing multi-channel setups. In this work, we present two tomographic frequency-modulated continuous wave (FMCW) systems working at a bandwidth of 230–320 GHz, equipped with an eight-channel detector array, and we compare their imaging results with those of a single-pixel setup. While in the first system the additional channels are used exclusively to detect radiation refracted by the sample, the second system features an f-θ lens, focusing the beam at different positions on its flat focal plane, and thus utilizing the whole detector array directly. The usage of the f-θ lens in combination with a scanning mirror eliminates the necessity of the formerly used slow translation of a single-pixel transmitter. This opens up the potential for a significant increase in acquisition speed, in our case by a factor of four to five, respectively.https://www.mdpi.com/1424-8220/24/2/529terahertz radiationcomputed tomographydetector arrayFMCWacquisition speednon-destructive testing |
| spellingShingle | Karl Henrik May Shiva Mohammadzadeh Andreas Keil Georg von Freymann Fabian Friederich Coherent Off-Axis Terahertz Tomography with a Multi-Channel Array and f-theta Optics Sensors terahertz radiation computed tomography detector array FMCW acquisition speed non-destructive testing |
| title | Coherent Off-Axis Terahertz Tomography with a Multi-Channel Array and f-theta Optics |
| title_full | Coherent Off-Axis Terahertz Tomography with a Multi-Channel Array and f-theta Optics |
| title_fullStr | Coherent Off-Axis Terahertz Tomography with a Multi-Channel Array and f-theta Optics |
| title_full_unstemmed | Coherent Off-Axis Terahertz Tomography with a Multi-Channel Array and f-theta Optics |
| title_short | Coherent Off-Axis Terahertz Tomography with a Multi-Channel Array and f-theta Optics |
| title_sort | coherent off axis terahertz tomography with a multi channel array and f theta optics |
| topic | terahertz radiation computed tomography detector array FMCW acquisition speed non-destructive testing |
| url | https://www.mdpi.com/1424-8220/24/2/529 |
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