Abstract-Enhancement of Real-Time THz Imaging System Based on 320 × 240 Uncooled Microbolometer Detector

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• Xing Zheng
• , Zhiming Wu,
•  Jun Gou
• , Ziji Liu
• , Jun Wang
• , Jie Zheng
• , Zhenfei Luo
• , Weiqing Chen
• , Dongcheng Que,

http://link.springer.com/article/10.1007%2Fs10762-016-0287-4

A real-time terahertz (THz) imaging system was demonstrated based on a 320 × 240 uncooled microbolometer detector combined with a 2.52 THz far-infrared CO2 laser. On the top of micro-bridge structure (35 × 35 μm2), a 10 nm nickel-chromium (NiCr) thin film was deposited to enhance THz absorption, which was fabricated by a combined process of magnetron sputtering and reactive ion etching (RIE). By mechanical simulation using design of experiment (DOE) method, the minimum deformation was optimized to 0.0385 μm, and a measured deformation of 0.097 μm was achieved in the fabrication. The fabricated micro-bridge pixel was used for THz detection, and a responsivity of 1235 V/W was achieved with a noise equivalent power (NEP) of 87.4 pW/Hz1/2. THz imaging of metal gasket covered by label paper, paper clip in an envelope, and watermark of a banknote was demonstrated by a combination of histogram equalization (HE) and linear enhancement algorithm.