Fusion of radar and optical images for person screening in security sensitive environments

Recent terror attacks showed the vulnerability of our public life. That is why, a lot of security systems have been developed; especially for person screening on airports. However, sometimes images with anatomic details are produced violating the human privacy rights. To avoid it, mostly stylised avatars are shown on which the locations of the detected prohibited items on the body are marked. This, however, gives only a coarse orientation. In this paper, a better way is proposed by fusing the images of a radar sensor and an optical sensor. The radar image is generated by a rotating millimetre wave FMCW radar operating between 96 GHz and 99 GHz. It consists of a one transmitter and five receivers in order to scan the person from different aspect angles. The RF front end consists of a monolithic microwave integrated circuit with a chip size of 2x3 mm. The circuit features coplanar technology and cascode HEMTs for compact size and low cost. The optical image is generated by a time of flight (ToF) camera system which is able to measure the distance between the camera and a reflecting point by measuring the elapsed time. Hence, the ToF principle is quite similar to a radar (active ranging system), that needs an illumination source. To measure the distances, the light has to be modulated adequately. Then, it is possible to evaluate it as the modulation of the back-scattered signal differs from that of the emitted one. Mostly, the near infrared area is used for this purpose, because it is invisible and simultaneously not harmful for the human eye. Both, optical and radar image are superimposed showing the exact location of concealed objects worn under the cloths. For this purpose, perspective distortions are removed by a complex mathematic model considering the dimensions and the physical inner structure of the CMOS ToF chip array

Sensor fusion based security concept on airports with a rotating millimetre wave person scanner

This paper gives an overview about a new security concept on airports. Because single systems have not often the desired reliability, the concept is based on the fusion of different sensors. Moreover, first measurements of a 94 GHz person scanner with circular synthetic aperture are presented showing the capability to detect metallic as well as nonmetallic objects without violating the personal privacy

Optical 3D assisted CSAR for security screening at a constant passenger flow

In times of increasing terror, elementary infrastructures like airports have to be protected. But, there are also some unsolved problems dealing with this topic, especially about security screening systems. Privacy protection for example is extremly controversial discussed in public. Furthermore, the increasing amount of passengers causes an increasing idle time in front of security checks. This paper presents a solution for both problems by use of a circular synthetic aperture radar (CSAR) with millimetre-wave (mmw) sensors in a vertical manner and an assistance of optical 3D sensors