Experimental realization of SDA-method for the detection of substance at long distance

Vyacheslav A. Trofimov; Anton D. Denisov; Vasily V. Tikhomirov

doi:10.1117/12.2029007

16 October 2013 Experimental realization of SDA-method for the detection of substance at long distance

Vyacheslav A. Trofimov, Anton D. Denisov, Vasily V. Tikhomirov

Proceedings Volume 8901, Optics and Photonics for Counterterrorism, Crime Fighting and Defence IX; and Optical Materials and Biomaterials in Security and Defence Systems Technology X; 890108 (2013) https://doi.org/10.1117/12.2029007
Event: SPIE Security + Defence, 2013, Dresden, Germany

Abstract

Nowadays, the detection and identification of dangerous substances at long distance (several metres, for example) by using of THz pulse reflected from the object is an important problem. The main problem with this technique is the absorption of THz energy by water vapor. However, using THz pulsed radiation is possible at distance of some metres as it is well-known. Below we demonstrate possibility of THz signal measuring reflected from a flat metallic mirror placed about 3.2 metres from the parabolic mirror. Investigated object is placed before this mirror. Therefore, at present time our measurements contain features of both transmission and reflection modes. The reflecting mirror is used because of weak averaged power of femtosecond laser. This power is about 1 W. Nevertheless, the laser beam splits many times. Therefore, the averaged power falling on the THz emitter decreases at least 8 times. The pulse duration generated by the femtosecond laser is equal to 68 fs. In this mode of measurements we took measurements for a chocolate brick, cookies, a bag made from thick paperboard, many layers of thin papers (paper napkin for computer monitor). In particular, it should be stressed that a spectrum of the measured signal is highly sensitive to a angle position of the flat mirror. Therefore, at long distance the position of object, that reflects the THz pulse, will influence essentially on the measured spectrum. Other very important features of the measurements with the multilayer of paper are the strong modulation of the spectrum of the reflected signal. As a consequence, we see additional frequencies, which correspond to absorption frequencies of various explosives, in the spectrum of the reflected signal. In fact, these substances are absent in our experiment. The last important result consists of unusual influence of the cookies on the measured signal: it becomes strong modulated. Consequently, cookies act as disordered structures.

Citation Download Citation

Vyacheslav A. Trofimov, Anton D. Denisov, and Vasily V. Tikhomirov "Experimental realization of SDA-method for the detection of substance at long distance", Proc. SPIE 8901, Optics and Photonics for Counterterrorism, Crime Fighting and Defence IX; and Optical Materials and Biomaterials in Security and Defence Systems Technology X, 890108 (16 October 2013); https://doi.org/10.1117/12.2029007

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available