Cost-efficient delay generator for fast terahertz imaging

Probst, T.; Rehn, Arno; Busch, Stefan; Chatterjee, Sangam; Koch, Martin; Scheller, Maik

doi:10.1364/ol.39.004863

Cited by 16 publications

(12 citation statements)

References 13 publications

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“…Using the QTDS technology, compact, lightweight, battery-powered measurement systems for the use in the field get within reach. New compact, robust, and inexpensive delay concepts like the one proposed by Probst et al [53] are an important step in this direction.…”

Section: Reviewmentioning

confidence: 99%

Monitoring leaf water content with THz and sub-THz waves

2015

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Terahertz technology is still an evolving research field that attracts scientists with very different backgrounds working on a wide range of subjects. In the past two decades, it has been demonstrated that terahertz technology can provide a non-invasive tool for measuring and monitoring the water content of leaves and plants. In this paper we intend to review the different possibilities to perform in-vivo water status measurements on plants with the help of THz and sub-THz waves. The common basis of the different methods is the strong absorption of THz and sub-THz waves by liquid water. In contrast to simpler, yet destructive, methods THz and sub-THz waves allow for the continuous monitoring of plant water status over several days on the same sample. The technologies, which we take into focus, are THz time domain spectroscopy, THz continuous wave setups, THz quasi time domain spectroscopy and sub-THz continuous wave setups. These methods differ with respect to the generation and detection schemes, the covered frequency range, the processing and evaluation of the experimental data, and the mechanical handling of the measurements. Consequently, we explain which method fits best in which situation. Finally, we discuss recent and future technological developments towards more compact and budget-priced measurement systems for use in the field.

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Section: Reviewmentioning

confidence: 99%

Monitoring leaf water content with THz and sub-THz waves

2015

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“…Fast linear piezo stages exist, but they are also expensive and the oscillating movement at rates of several Hertz require unreasonable engineering efforts for the optics mounts on top of the stage. The last technique, using a rotating glass plate as a delay, is known from applications such as optical auto-correlation [19] and terahertz imaging [20]. It is depicted in figure 2.…”

Section: Methodsmentioning

confidence: 99%

Fast time-domain measurements on telecom single photons

Allgaier

Vigh

Ansari

et al. 2017

Quantum Sci. Technol.

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Abstract. Direct measurements on the temporal envelope of quantum light are a challenging task and not many examples are known since most classical pulse characterisation methods do not work on the single photon level. Knowledge of both spectrum and timing can however give insights on properties that cannot be determined by the spectrum alone. While temporal measurements on single photons on timescales of tens of picoseconds are possible with superconducting photon detectors and picosecond measurements have been performed using streak cameras, there are no commercial single photon sensitive devices with femtosecond resolution available. While time-domain sampling using sumfrequency generation has been already exploited for such measurement, inefficient conversion has necessitated long integration times to build the temporal profile. We demonstrate a highly efficient waveguided sum-frequency generation process in Lithium Niobate to measure the temporal envelope of single photons with femtosecond resolution with short enough acquisition time to provide a live-view of the measurement. We demonstrate the measurement technique and combine it with spectral measurements using a dispersive fiber time-of-flight spectrometer to determine upper and lower bounds for the spectral purity of heralded single photons. The approach complements the joint spectral intensity measurements as a measure on the purity can be given without knowledge of the spectral phase.arXiv:1702.03240v1 [quant-ph]

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“…Currently, a slow linear delay line is used for the THz pulse acquisition, thus limiting per pixel pulse acquisition rates to 1 Hz. Slow linear delay lines can be substituted by the much faster rotary delay lines that were recently demonstrated by several research groups [13][14][15][16][17][18][19][20][21] that can enhance acquisition rate to ~10-100Hz. In fact, mechanical optical delay lines can be replaced altogether by the opto-electronic delay lines integrated into the fs lasers used in the TDS-THz systems, thus resulting in full THz spectral scanning rates of ~100Hz per pixel [12].…”

Section: Advantages and Limitations Of The Hybrid Imaging Algorithmmentioning

confidence: 99%

Exploiting k-space/frequency duality in Fourier optics toward real-time compression less terahertz imaging

Guerboukha

Nallappan

2018

Computational Imaging III

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We present theoretical formulation and experimental demonstration of a novel technique for the fast compression-less terahertz imaging based on the broadband Fourier optics. The technique exploits k-vectorfrequency duality in Fourier optics which allows using a single-pixel detector to perform angular scan along a circular path, while the broadband spectrum is used to scan along the radial dimension in Fourier domain. The proposed compression-less image reconstruction technique (hybrid inverse transform) requires only a small number of measurements that scales linearly with the image linear size, thus promising real-time acquisition of high-resolution THz images. Additionally, our imaging technique handles equally well and on the equal theoretical footing the amplitude contrast and the phase contrast images, which makes this technique useful for many practical applications. A detailed analysis of the novel technique advantages and limitations is presented, as well as its place among other existing THz imaging techniques is clearly identified.

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Cost-efficient delay generator for fast terahertz imaging

Cited by 16 publications

References 13 publications

Monitoring leaf water content with THz and sub-THz waves

Monitoring leaf water content with THz and sub-THz waves

Fast time-domain measurements on telecom single photons

Exploiting k-space/frequency duality in Fourier optics toward real-time compression less terahertz imaging

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