XXX-X-XXXX-XXXX-X/XX/$XX.00 ©20XX IEEE Incoherent Active Millimeter-Wave Imaging Using Forward-Illuminating Source Atsuro MAEDA School of Engineering Tohoku University Sendai city, Japan maeda-a@ecei.tohoku.ac.jp Hiroyasu SATO Graduate School of Engineering Tohoku University Sendai city,Japan sahiro@ecei.tohoku.ac.jp Qiang CHEN Graduate School of Engineering Tohoku University Sendai city, Japan chenq@ecei.tohoku.ac.jp Abstract— In this paper, the forward illuminating source is applied to the passive millimeter-wave (PMMW) imaging technique in order to improve contrast between the objects and human body. Imaging data for the cases of several material are compared with changing the geometry of materials. As a result, the relation is clarified between the imaging data and the analytic reflectivity, emissivity and transmittance. I. INTRODUCTION Some materials of liquid, plastics and powder can be ingredients for explosives, and subversive activities such as terrorism have been brought by using handmade bomb made of such dielectric materials. It is easy to hide them in clothes and development of detection system for concealed artifacts is strongly desired for the purpose of keeping safe and secure aircrafts, ships and train etc. Imaging of concealed objects in clothes is possible in a noninvasive and noncontact manner by using the passive millimeter-wave (PMMW) imaging techniques [1]. All substances radiate the thermal noise. Power of the thermal noise is proportional to the brightness temperature in millimeter-wave band. PMMW imaging device is composed of a lens, the imaging sensor array placed in the image plane and a signal/image processing system which forms the PMMW images. Considering the detection of scattering objects with high reflectivity such as the conducting material, the thermal noise radiated from the surrounding objects in a room such as the walls, the fluorescents, the human bodies and the electric devices, incident to the objects in clothes and reflected by them. Then the PMMW imaging device images the scattering objects as the brightness temperature of apparent values. Therefore, the contrast depends on a surrounding temperature environment and the contrast becomes lower as the physical temperature of surrounding objects in a room increase. In order to overcome this problem, the effect of illumination to a human body and objects to increase the contrast of PMMW imaging were investigated [2, 3]. Fig. 1 Optical system of Sub-Active imaging. Also the received power with different geometry and various type of materials were evaluated and were compared with the analytic reflectivity, emissivity, transmittance. II. OPTICAL SYSTEM WITH ILLUMINATING SOURCE 77 GHz-band PMMW imaging device developed in [1] was used for the experiment. Figure 1 shows the simplified optical system of PMMW imaging device and arrangement of other equipment. PMMW imaging device is composed of a dielectric lens with diameter of 500 mm and one-dimensional imaging sensor array of 48-elements located at the image plane. Also a flapping reflector synchronized to the signal/image processing have been employed to obtain 2-dimmensional images by using one-dimensional 48array elements. A human body stands at the object plane. Two plate objects fixed by a Styrofoam are located in front of the human body. A parabolic reflector with a focal length of almost f=200 mm were used as an illuminating source. A millimeter wave source module with an aperture of y z 48- Imaging sensor array Lens Human body Objects Object plane x MM-wave module Parabolic reflector Focal point q 1 q 2 q 1 =q 2 Illuminating source SG