"The differences in reflectance values for those pure liquids except for water and hydrogen peroxide are relatively high. This difference in reflectivity might be of different sign and show even lower absolute values for H 2 O 2 /H 2 O mixtures depending on the concentrations . For the liquid identifier presented here, it was sufficient to use YBa 2 Cu 3 O 7-x -tilt bicrystal grainboundary Josephson junctions with I c R n -values of 100-250 μV (with critical current I c and normal state resistance R n of the junction), corresponding to characteristic frequencies of about 50 to125 GHz, as most liquids show their main dispersion changes below around 1 THz. "
[Show abstract][Hide abstract] ABSTRACT: Fast and reliable detection of liquids will be required for future checkpoint screening techniques. Recently, a new electromagnetic-wave concept based on our high-T c Josephson detectors and Hilbert spectroscopy has been suggested to distinguish between liquids. This technology covers a spectral range of main dispersions of liquids, from a few GHz to a few THz, and thus significantly enhances reliability of identification. The high-T c detectors, due to a power dynamic range of more than five orders, might guarantee short identification times. Several demonstration set-ups of liquid identifiers, consisting of high-T c Josephson detectors, integrated in Stirling coolers, and polychromatic radiation sources, have been developed and characterized. Reflection polychromatic spectra of various liquids in plastic containers have been measured at the spectral range of 15-500 GHz with total scanning time down to 0.2 second. Reliable identification of liquids, both benign and threat, within an accuracy of 0.3% was demonstrated using water as a reflectance reference. The reflectance values for 30%H 2 O 2 /H 2 O solution at frequencies of 30 and 100 GHz were practically undistinguishable from that of for pure water, but an increase of the relative reflectance from 1.017 at 282 GHz to 1.033 at 434 GHz has been found. Last circumstance will be used for optimization of the identifiers.
"To resolve this difference in reflectance measurements of pure water and hydrogen peroxide a signal/noise ratio of 20 dB is required. This difference in reflectivity might be of different signs and even lower absolute values for mixtures of various relative concentrations . For example, to distinguish from solution, accuracy of reflection measurements should be better than 25 dB. "
[Show abstract][Hide abstract] ABSTRACT: One of future public security techniques will be related with non-invasive, fast and reliable detection of liquids. To distinguish between liquids under concern, we have suggested a concept using our Hilbert spectroscopy, based on high- Tc Josephson junctions. This spectroscopy is the only technique, which covers a frequency range of main dispersions of liquids from a few GHz to a few THz. Several demonstration setups of liquid identifiers, consisting of Hilbert spectrometers integrated on Stirling coolers and polychromatic radiation sources, have been developed. A critical consideration of the main sources of fluctuations in these measurements was carried out and a signal accuracy of around 0.3% has been reached with a total measurement time of a few seconds. Identification of samples of benign and threat liquids was demonstrated.
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.