Version 1
: Received: 29 November 2023 / Approved: 30 November 2023 / Online: 30 November 2023 (04:09:20 CET)
Version 2
: Received: 12 December 2023 / Approved: 13 December 2023 / Online: 13 December 2023 (05:08:53 CET)
May, K.H.; Mohammadzadeh, S.; Keil, A.; von Freymann, G.; Friederich, F. Coherent Off-Axis Terahertz Tomography with a Multi-Channel Array and f-theta Optics. Sensors2024, 24, 529.
May, K.H.; Mohammadzadeh, S.; Keil, A.; von Freymann, G.; Friederich, F. Coherent Off-Axis Terahertz Tomography with a Multi-Channel Array and f-theta Optics. Sensors 2024, 24, 529.
May, K.H.; Mohammadzadeh, S.; Keil, A.; von Freymann, G.; Friederich, F. Coherent Off-Axis Terahertz Tomography with a Multi-Channel Array and f-theta Optics. Sensors2024, 24, 529.
May, K.H.; Mohammadzadeh, S.; Keil, A.; von Freymann, G.; Friederich, F. Coherent Off-Axis Terahertz Tomography with a Multi-Channel Array and f-theta Optics. Sensors 2024, 24, 529.
Abstract
Terahertz tomography is a promising method among non-destructive inspection techniques to detect faults and defects in dielectric samples. Image quality recently significantly improved through the incorporation of a priori 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 compare their imaging results with 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.
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Commenter: Karl Henrik May
Commenter's Conflict of Interests: Author