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In recent years, terahertz frequency bands have attracted more and more attention due to their unique advantages, and terahertz imaging technology is developing into a new supplementary means of non-destructive testing. We have conducted in-depth research on terahertz non-destructive testing technology and developed a terahertz detector that can be used for non-destructive testing of wood. The detector mainly includes terahermet transceiver, signal processing system and data acquisition system. In order to achieve three-dimensional imaging, fast frequency sweep and the best anti-interference ability when detecting targets, wideband chirp continuous wave was selected as the radiation waveform of the system. In order to improve the ranging accuracy and three-dimensional imaging performance, a fully coherent form suitable for the terahertz band was selected. Based on the superheterodyne detection structure, the three-dimensional reconstruction of the sample is realized by the data acquisition system. On this basis, we use the self-developed quantum image data processing system to perform quantum image enhancement processing on the acquired three-dimensional reconstructed images, which further improves the contrast and clarity of the images, and is especially prominent in the noise environment, and has made significant progress in presenting details and information extraction. The center frequency of the terahertz detector is about 200GHz, the dynamic range is large, the operating distance can reach about 1m, and the distance resolution and direction resolution can reach the millimeter level. It lays the foundation for high-quality three-dimensional imaging and provides an effective way for non-destructive testing of non-metallic materials. Also,it can be applied to non-destructive testing of remote sensing target information.
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