Synthetic Aperture Terahertz Imaging with an Optoelectronic FMCW Radar

Keil, Andreas; Mohammadzadeh, Shiva; Liebermeister, Lars; Schwenson, Lauri; Globisch, Björn; Friederich, Fabian

doi:10.23919/eurad54643.2022.9924725

Cited by 3 publications

(1 citation statement)

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“…In addition to the unprecedented bandwidth of a terahertz FMCW radar to the best of our knowledge, the optoelectronic continuous wave concept offers a simple possibility to distribute terahertz modulated signals by means of optical fibers and thus to address several transmitter and receiver units simultaneously , e.g., as an imaging radar array. [ 26 ] The scalability is primarily limited by the laser power and can therefore be extended by using additional laser amplifiers. Furthermore, there is the potential to synchronize the laser beat signal with high‐frequency electronics, [ 27 ] which allows to benefit from their high stability and established radar system concepts in connection with the flexibility of optoelectronic signal distribution.…”

Section: Discussionmentioning

confidence: 99%

Extreme Ultra‐Wideband Optoelectronic Frequency‐Modulated Continuous‐Wave Terahertz Radar

Mohammadzadeh,

Keil,

Kocybik

et al. 2023

Laser & Photonics Reviews

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A novel photonic terahertz measurement system based on a frequency‐modulated continuous‐wave (FMCW) radar approach is presented. In previous works, fast frequency modulation has been demonstrated in connection with a continuous wave terahertz spectroscopy setup based on the photomixing principle. In this paper, a terahertz radar based on both a photomixing transmitter and a photomixing receiver, in contrast to the rigid spectroscopy approach, is reported. Hereby, frequency modulation bandwidths of more than 1.65 THz in radar operation is achieved. This corresponds to an order of magnitude more than what is previously achieved by terahertz radar systems. At the same time, measurement rates can be achieved that are comparable with radar systems based on Monolithic Microwave Integrated Circuits (MMICs) according to the current state of the art. Within the scope of the work, two operating modes are realized, one with a measurement rate of about 560 Hz at 600 GHz modulation bandwidth and one with 200 Hz at 1.65 THz modulation bandwidth, which can be set within the spectrum from 50 GHz to about 4.5 THz. The possibility to adjust the operating range of the radar without necessary hardware adaptations is another unique feature of the presented system, which allows the operator to choose a suitable frequency band that corresponds best to a certain measurement scheme via software settings. Besides the potential for multi‐layer thickness inspections, the capabilities of this technique for terahertz imaging applications are presented.

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Section: Discussionmentioning

confidence: 99%