THz Reflection Spectra of Different Materials, Including Explosives, Measured at a Distance up to 5 m
M. Walczakowski a, N. Palka a, A. CzerwiƄski b, M. Sypek b and M. Szustakowski a
aInstitute of Optoelectronics, Military University of Technology, S. Kaliskiego 2, 00-908 Warszawa, Poland
bWarsaw University of Technology, Koszykowa 75, 00-662 Warszawa, Poland
Received: May 12, 2014
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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.

DOI: 10.12693/APhysPolA.127.689
PACS numbers: 06.60.Ei, 07.57.Hm, 07.57.Kp, 07.57.Pt, 33.20.Ea