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Bottled liquid explosive detector using NIR

Hideo Itozaki 1 ; Masaki Ono 1 ; Shiori Ito 1 ; Keisuke Uekawa 1 ; Yuji Miyato 1 ; Hideo Akaba 1
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INTRODUCTION
In the airport, liquid is inhibited to be brought in by passengers for countermeasure of terrorist’ attacks. While, it is requested strongly to relax this regulations because of inconvenient and many troubles at the security gates. Here, a bottled liquid explosive detector has been developed using near infrared technology.
EXPERIMENTAL
The instrumental
　Basically this detector is constructed with light source of a halogen lump and a spectrometer using Si detectors. It is also has a control circuit board of the spectrometer, PC and LED light to indicate the result of evaluation.
Methods
Absorbance of transparent liquid in a transparent bottle can be obtained by a transmitting method and that of liquid with scattering particles such as milk can be obtained by a reflecting method. Avoiding large absorption of water, light wave length of 700-1000 nm is used.
Data treatment
Spectral data ara treated by the second derivatives and SNV and are checked by correlation analysis using liquid data base. If it is correlate to safe liquid, LED light indicate green signal. Otherwise light shows red.
Detail of the measurements
This detector is constructed by two poles. Both poles have a light source and one of them has inlet of spectrometer. Therefore it deals with both methods of transmitting and reflecting.
RESULTS AND DISCUSSION
Principal results obtained and their relevance
It is confirmed in our laboratory that spectrum of near infrared can be applied to the bottled liquid explosive detector. Liquid in colored bottle, such as wine can be identified, because the second derivative spectrum of colored bottles are almost flat. Then it has been used at Narita International airport and Kansai International airport in Japan as a feasibility tests. These test showed that our developed device worked so well to scan bottles carried by passengers in the airport. This device has been certified by ECAC (European Civil Aviation Conference) as level 2. The technologies of this detector is transferred to a Japanese company to be a commercial product.