Methodologies for determining the dynamic ranges and signal-to-noise ratios of terahertz time-domain spectrometers

Naftaly, Mira; Dudley, Richard

doi:10.1364/ol.34.001213

Cited by 156 publications

(85 citation statements)

References 4 publications

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“…Due to the fact that in our experiment, we analyzed the time-domain data, the performance of the system was determined also in time domain, according to the procedure described in [30]. The signal-to-noise ratio and the dynamic range are equal to 90 and 1500, respectively.…”

Section: Methodsmentioning

confidence: 99%

Precise Determination of Thicknesses of Multilayer Polyethylene Composite Materials by Terahertz Time-Domain Spectroscopy

Pałka

Krimi

Ospald

et al. 2015

J Infrared Milli Terahz Waves

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The multilayer structure of an ultra-high molecular weight polyethylene (UHMWPE) composite material was investigated in the terahertz (THz) spectral range by means of time-domain spectroscopy (TDS) technique. Such structures consist of many alternating layers of fibers, each being perpendicular to the other and each having a thickness of about 50 μm. Refractive indices of two composite samples and of a sample composed of four single layers (plies) having the same fiber orientation were determined for two orthogonal orientations of the electric field in a transmission TDS system. The birefringence of a single layer was measured, and the origin of this phenomenon is discussed. Using the TDS system in reflection, the formation of many pulses shifted in time was observed originating from reflections from interfaces of successive layers caused by the periodic modulation of the refractive index along the propagation of the THz radiation. This phenomenon is theoretically described and simulated by means of a transfer matrix method (TMM). A time-domain fitting procedure was used to determine thicknesses of all layers of the composite material. The reconstructed waveform based on the optimized thicknesses shows very good agreement with the measured waveform, with typical differences between measurements and simulations J Infrared Milli Terahz Waves (2015) between 3 and 7 μm (depending on the sample). As a result, we were able to determine the thicknesses of all layers of two multilayer (~200 plies) structures by means of the reflection TDS technology with high accuracy.

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Section: Methodsmentioning

confidence: 99%

Precise Determination of Thicknesses of Multilayer Polyethylene Composite Materials by Terahertz Time-Domain Spectroscopy

Pałka

Krimi

Ospald

et al. 2015

J Infrared Milli Terahz Waves

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“…Such spectra are available when the influence of water vapour is minimized by purging the chamber with dry air. To assess system performance, the signal-to-noise ratio and dynamic range were determined in the frequency domain according to the algorithm presented in [24] (Fig. 3).…”

Section: Experimental and Data Analysismentioning

confidence: 99%

Transmission and Reflection Terahertz Spectroscopy of Insensitive Melt-Cast High-Explosive Materials

Pałka

Szala

2016

J Infrared Milli Terahz Waves

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Currently, artillery shells and grenades that are introduced into the market are based on melt-castable insensitive high explosives (IHEs), which do not explode while they run a risk of impact, heat or shrapnel. Particles of explosives (such as hexogen, nitroguanidine and nitrotriazolone) are suspended in different proportions in a matrix of 2.4-dinitroanisole. In this paper, we investigated samples of commonly used IHEs: PAX-41, IMX-104 and IMX-101, whose internal structures were determined by a scanning electron microscope. Terahertz time domain spectroscopy was applied in both transmission and reflection configurations. At first, the complex refraction indices of four pure constituents creating IHEs were determined and became the basis of further calculations. Next, the experimentally determined transmission and reflection spectra of IHEs and pure constituents were compared with theoretical considerations. The influence of the grain size of constituent material and scattering on the reflection spectra was analysed, and good agreement between the experimental and theoretical data was achieved.

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“…The parameters commonly used are the dynamic range (DR) and the signal-to-noise ratio (SNR), which mainly affect the accuracy in THz measurements. They should always be evaluated during the measurements, to avoid false interpretation of the results; therefore, some recommendations for the best practice are presented [31].…”

Section: Performance Of Thz Systemsmentioning

confidence: 99%

THz Measurement Systems

Angrisani¹,

Cavallo²,

Liccardo³

et al. 2016

New Trends and Developments in Metrology

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The terahertz (THz) frequency region is often defined as the last unexplored area of the electromagnetic spectrum. Over the past few years, the full access has been the objective of intense research efforts. Progress in this area has played an important role in opening up the possibility of using THz electromagnetic radiation (T-waves) in science and in realworld applications. T-waves are not perceptible by the human eye, are not ionizing, and have the ability to cross many non-conducting materials such as paper, fabrics, wood, plastic, and organic tissues. Moreover, the use of THz radiation allows non-destructive analysis of the materials under investigation both by study of their "fingerprint" via spectroscopic measurements and by high-resolution spatial imaging operations, exploiting the see-through capability of T-waves. Such technology can be applied in diverse areas, spanning from biology to chemical, pharmaceutical, environmental sciences, etc. In this chapter, we will present the typical architecture of measurement systems based on the THz technology, detailing what are the parameters that define their performance, the measurement methods, and the related errors and uncertainty, and focusing at the end on the use of time-domain spectroscopy for the evaluation of different material properties in this specific frequency region.

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Methodologies for determining the dynamic ranges and signal-to-noise ratios of terahertz time-domain spectrometers

Abstract: We discuss procedures for calculating the signal-to-noise ratios and the dynamic ranges of terahertz time-domain spectrometers. We also offer recommendations for standardized calculations for time-domain and frequency-domain data.

Cited by 156 publications

References 4 publications

Precise Determination of Thicknesses of Multilayer Polyethylene Composite Materials by Terahertz Time-Domain Spectroscopy

Precise Determination of Thicknesses of Multilayer Polyethylene Composite Materials by Terahertz Time-Domain Spectroscopy

Transmission and Reflection Terahertz Spectroscopy of Insensitive Melt-Cast High-Explosive Materials

THz Measurement Systems

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