Investigations on the high-performance passive terahertz imaging system based on the BIB detector

Passive terahertz detection has a wide range of prospective applications due to its advantages of non-invasiveness, no radiation, strong penetration, high resolution and high sensitivity. A terahertz imaging system based on BIB detector is developed, which includes a BIB detector module, a cryogenic module, a cryogenic optical module and a high-precision temperature control module. The detailed design scheme is carried out. Loss mechanism of cryogenic optical at different temperatures is elaborated to improve the sensitivity of the system. The coupling and matching relationships among the cryogenic system, the detector and the cryogenic optical are emphatically analyzed. The experimental test of neuronal samples is performed. Results indicate that the BIB detector and cryogenic optical work in the low-temperature of 3.2 K and 47 K, of which the temperature control accuracy are 3.5 mK and 9.5 mK, respectively. The spatial resolution of the terahertz imaging system can reach 50 μm, which has high imaging quality. The good agreements between simulations and experiments are observed. The above analyses have important practical significance for passive terahertz detection in space astronomical exploration, biological nondestructive detection, and security check.