Near infrared inspection technology of bottled explosive liquid in airports

Near infrared inspection technology of bottled explosive liquid has been developed to be used in airports for anti-terrorism. Near infrared absorbance of 700 nm–1000 nm is used to inspect liquids in a bottle. Influence of bottle’s color can be avoided if the second derivative of absorbance at wavelength of more than 800 nm is used to inspect colored bottles. Suspension liquid such as milk can be inspected by reflected light. As various bottled liquids are carried into the airport by passengers, hundreds of bottled liquid such as beverages (soft and hard drinks), cosmetics, perfumes, medicines, shampoos, and so on were collected and their near infrared absorbance spectra were obtained to make a database of discrimination. Correlation coefficient is used to discriminate these liquids. And safe liquid or explosives was identified instantly. An ultrasonic pulse method was also applied to inspection of liquid in a metal can. Kumahira Co. Ltd developed a commercialized product. It was certified by the most reliable evaluation organization European Civil Aviation Conference. In 2019, more than 300 devices have been installed in Japanese airports for anti-terrorism, and some of them have been installed in Japanese Customs to inspect smuggling drugs. The liquid inspection technology can be applied not only in airports but also in many kinds of public places for the safety of public. Near infrared technology has large potential to be applied in more and more fields.