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1
Content available remote

Complex THz Reflectance Spectra of Hexogen Measured for Various Surfaces

100%
Palka N.
Acta Physica Polonica A
|
2012
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vol. 122
|
issue 5
854-857
EN
In this paper, we report on measurements of reflection spectra of hexogen (RDX) by means of time domain spectroscopy. We analyzed both phase and amplitude of reflected impulses for three cases: detuning, samples with rough surfaces and samples with curved surfaces. It can be concluded that both spectral characteristics can be applied for identification of explosives in the reflection configuration.
2
Content available remote

Spectroscopy of Explosive Materials in the THz Range

100%
Palka N.
|
|
issue 6
1229-1231
EN
Absorption spectra of hexogen and penthrite-2 commonly used explosive materials in the range 0.3-3 THz are presented. The measurements were carried out by means of time domain spectroscopy and compared to spectra obtained by Fourier transform infrared spectroscopy. Good conformity is observed.
3
Content available remote

THz Reflection Spectroscopy of Explosives Measured by Time Domain Spectroscopy

100%
Palka N.
Acta Physica Polonica A
|
2011
|
vol. 120
|
issue 4
713-715
EN
Reflection spectra of pure explosive materials and their simulants were measured in transmission and reflection by means of time domain spectroscopy in the range 0.1-3 THz. Spectra measured in two reflection configurations: specular with incident angle equal to 45° and stand-off with close to normal incidence and distance 30 and 40 cm to samples was analyzed.
4
Content available remote

Coupling in Core-Ring Photonic Crystal Fibers

51%
Palka N., Ciurapiński W., Wojcik J., Szustakowski M.
Acta Physica Polonica A
|
2008
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vol. 114
|
issue 6A
A-157-A-161
EN
Experimental investigations of light coupling from a core into a ring caused by microbendings in photonic crystal fibres are shown. We present a setup arrangement, mode fields with and without coupling and a plot of power transfer versus localisation of the modulator along the fibre. We also show the most probable explanation of the obtained data.
5
Content available remote

Terahertz Spectra of Explosives Measured by Optical Parametric Oscillator-Based System and Time Domain Spectroscopy

51%
Palka N., Trzcinski T., Szustakowski M.
Acta Physica Polonica A
|
2012
|
vol. 122
|
issue 5
946-949
EN
In this paper, we report on measurements of absorption spectra of hexogen, penthrite, and octogen. The measurements were carried out by means of time domain spectroscopy and compared to spectra obtained from a setup, which bases on an optical parametric oscillator combined with a Golay cell. For time domain spectroscopy measurement, Teraview TPS 3000 unit with accessories in transmission configuration was used.
6
Content available remote

Focusing with 2D Square Photonic Crystal with Concavo-Concavo Boundaries

51%
Palka N., Ciurapinski W., Wróbel J.
Acta Physica Polonica A
|
2009
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vol. 116
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issue 3
368-370
EN
We studied focusing properties of 2D square photonic crystal with concavo-concavo boundaries. The photonic crystal is built by air holes in a uniform dielectric. The incident plane wave propagates through a section of the photonic crystal and efficient focusing is observed by finite difference time domain simulations. To analyze the properties of photonic crystal we calculated the photonic band structure and equal frequency contours for TE modes. In our simulation we consider influence of geometry of the concave structures on the focusing properties.
7
Content available remote

Hidden Object Detection System Based on Fusion of THz and VIS Images

51%
Kowalski M., Palka N., Piszczek M., Szustakowski M.
Acta Physica Polonica A
|
2013
|
vol. 124
|
issue 3
490-493
EN
Terahertz imaging makes it possible to acquire images of objects concealed underneath clothing by measuring the radiometric temperatures of different objects on a human subject. Finding objects hidden under clothes is one of key issues of public places security. A possible solution of this problem is a multispectral, terahertz-based screening system with implemented image fusion algorithm. The result of the fusion is a new image which gives more information and is more suitable for human perception. An imaging system is usually composed of various subsystems. Many of the imaging systems use imaging devices working in various spectral ranges. The aim of our studies is to detect and visualize objects hidden under clothing. Detection of potentially dangerous objects is important, but without proper visualization, can be difficult to utilize. Our goal is to build a system harmless to humans for screening and detection of hidden objects using a THz and VIS cameras. The presented system draws attention not only on the properties offered by a single camera but also on the potential of synergetic effects of the system by using the fusion of data registered by different sensor units. In this paper we present the multispectral passive imaging system for hidden threats visualization based on THz and VIS cameras.
8
Publication available in full text mode
Content available

THz spectroscopy of explosive-related simulants and oxidizers

51%
Trzcinski T., Palka N., Szustakowski M.
|
2011
|
issue 4
9
Content available remote

THz Reflection Spectra of Different Materials, Including Explosives, Measured at a Distance up to 5 m

45%
Walczakowski M., Palka N., Czerwiński A., Sypek M., Szustakowski M.
Acta Physica Polonica A
|
2015
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vol. 127
|
issue 3
689-692
EN
This work presents a terahertz system designed for the reflection spectroscopy of different materials located at a distance up to 5 m. The source of the radiation is a tunable solid-state optical parametric oscillator, which generates a narrow-band nanosecond pulses in the range of 0.7-2.5 THz. The signal is detected with relatively fast and having big sensitivity hot electron bolometer. The detailed description of each device and the functioning of the experimental setup are provided as well as the methodology of the measurement is explained. Investigations were performed in the 0.7-2.2 THz range in free space with relative humidity of about 40%. The experiment was divided into three series, each of which was carried out with different distance between the examined sample and the system - 1 m, 3 m, and 5 m. Obtained spectra of selected materials, including explosives, are similar to the results received from a purged time domain spectroscopy system. The observed small deviations are connected with fluctuations of the laser wavelength and the instability of the bolometer.
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