Ultra-Wideband Terahertz 3D Imaging with Aspherical Telecentric f-θ Optics

Mohammadzadeh, Shiva; Klier, Jens; Seewig, Jörg; Freymann, Georg von; Friederich, Fabian

doi:10.1109/irmmw-thz57677.2023.10299330

Cited by 3 publications

(3 citation statements)

References 7 publications

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“…It is fabricated out of high-density polyethylene (HDPE) using computer numerical control (CNC) milling. The refractive index and the absorption coefficient of HDPE do not vary significantly in the frequency range in use (230 to 320 GHz), as shown in [ 33 ]. In their work, Mohammadzadeh et al applied a similar lens made from HDPE in an optical setup with a bandwidth of 1.65 GHz.…”

Section: Methodsmentioning

confidence: 94%

“…These objective lenses are increasingly applied in microwave and terahertz applications for non-destructive testing, 3D imaging [30], food safety inspection [31,32], etc. Thanks to the non-dispersive characteristics of the available lens fabrication material in terahertz and sub-terahertz, f-θ lenses are incorporated in various transmitters and receivers Sensors 2024, 24, 529 4 of 14 operating in this frequency region, such as FMCW radars with varying bandwidths [30,33] and TDS systems up to 1.25 THz [34,35].…”

Section: Design Of the F-θ Opticsmentioning

confidence: 99%

See 1 more Smart Citation

Coherent Off-Axis Terahertz Tomography with a Multi-Channel Array and f-theta Optics

May,

Mohammadzadeh,

Keil

et al. 2024

Sensors

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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 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 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.

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Section: Methodsmentioning

confidence: 94%

Section: Design Of the F-θ Opticsmentioning

confidence: 99%

Coherent Off-Axis Terahertz Tomography with a Multi-Channel Array and f-theta Optics

May,

Mohammadzadeh,

Keil

et al. 2024

Sensors

Self Cite

View full text Add to dashboard Cite

show abstract

“…These objective lenses are increasingly applied in microwave and terahertz applications for 3D imaging [22], food safety inspection [23], non-destructive testing [24], etc. Thanks to the nondispersive characteristics of the available lens fabrication material in terahertz and sub-terahertz, f-θ lenses are incorporated with various transmitters and receivers operating in this frequency region, such as FMCW radars with varying bandwidths [22,24,25] and TDS systems up to 1.25 THz [26].…”

Section: Design Of the F-θ Opticsmentioning

confidence: 99%

Coherent Off-Axis Terahertz Tomography with a Multi-Channel 2 Array and F-theta Optics

May,

Mohammadzadeh,

Keil

et al. 2023

Preprint

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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.

show abstract