Imaging Technologies in the Millimeter Wave Region


Imaging technologies using millimeter (mm) i) Plasma diagnostics waves offer unique measurement means in many apThe optics for mm-wave imaging radar systems can plication areas. We discuss here mm-wave focal plane be designed using the ray tracing method. Figure 2 imaging technologies whose resolution is limited by shows the 70 GHz optics designed for measuring 2diffraction amd also mm-wave scanning near-field midimensional plasma density profile in a plasma machine croscopy whose resolution is much smaller than operfor nuclear fusion research at the University of Tsukuba. ating wavelength. Results of our researches on both of Figure 3 shows measured time-revolution of 2-dimenthese imaging technologies are presented. sional plasma density profile [5]. 1. MM-wave Imaging Parabololdal Ellipsoidal Millimeter wave focal plane imaging [I ] is able to Mirror Mirror provide image information through clouds, smoke, and Hr s-Detecto r dust when visible and IR systems are unusable. It can .Piasm KtystronM r °• also be used in the fields of plasma measurement, re70.tG•, Mirror Irrr Lens mote sensing, etc. The resolution of the focal plane 00'W) Vacuum Vacuum imaging is limited by diffraction and is the order of widow Window wavelength, while scanning near field microscopy if.. 'GH 2O,, W) achieves sub-wavelength resolution [21, which offers ,tI., other applications of millimeter wave imaging technolo5--t-nPhat D gies. Fig. 2 Phase imaging system for plasma diagnostics 2. Focal plane imaging (Imaging arrays) Z=972.Scm Conventional millimeter wave imaging relies E mainly on the use of a single detector, with the optics : 0.8 mechanically scanned to obtain an image. The use of . 0.4 0.8 multiple detectors in an imaging array, however does 0 o0.4 0 0.2 not require mechanical scanning and makes real-time 0 0 imaging possible. Figure 1 shows a 60 GHz imaging 8 60 80 10 120 140 160 array [3,4] which consists of 2-element Yagi antennas with beam-lead Schottky diodes at the center of the Z= ---"antennas. The interval betw een the antennas w as deter. 0.18 S mined by the sampling theorem to obtain the diffrac,0. tion-limited image. 0.4 0. " -40 0 . Millimeter-wave 8 6 80 100 120 140 160 Object 6o 80..00

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Cite this paper

@inproceedings{MizunoImagingTI, title={Imaging Technologies in the Millimeter Wave Region}, author={Koji Mizuno} }