基于微等离子体的太赫兹波焦平面实时成像阵列的研究

太赫兹(THz)波实时成像技术在无损检测、安检等领域具有广阔的应用前景，而目前使用的THz波焦平面阵列存在诸多缺陷。本项目研究基于微等离子体的THz波焦平面实时成像阵列，探索THz时域光谱技术诊断微等离子体的新方法，获得微等离子体的直流放电特性；利用Drude-Lorentz模型研究THz波与微等离子体作用的物理过程，并用时域有限差分法模拟，揭示微等离子体探测THz波的物理机理，获得气体组分、压强、放电电流、电极结构等因素对探测效果的影响规律。研制微等离子体探测器阵列，用单片机控制工作模式，降低功耗和成本；研究锁相读数技术和外差探测技术，提高信噪比。性能指标达到：像素320×240，功率<0.1W，响应率>5000V/W，NEP<1pW/Hz^(1/2)，成像速度10帧/秒，频率响应范围0.1-10THz，室温操作。本项目对推动THz成像技术的广泛应用及对微等离子体特性的研究具有重要意义。

Terahertz (THz) wave real time imaging has promising applications in the fields of nondestructive examination, security detection and so on, however, the present THz focal plane arrays (FPAs) has many defects. The conventional plasma generated by inert gas discharge has been used in THz wave detection, and microplasma has more detection efficiency and stability, so this proposal will investigate an FPA based on microplasma for THz wave real time imaging. Firstly, we will explore the diagnosis method for microplasma using THz time-domain spectroscopy technology, and investigate the characteristics of microplasma generated by DC discharge. Then, we will study the physical process of the interaction between THz waves and micro plasma by Drude-Lorentz model and simulate it by finite-difference time-domain method to reveal the physical mechanism of THz wave detection by microplasma and find the influence rules of detection efficiency related with gas components, pressure, discharge current, structure of electrodes, and so on. An microplasma array will be developed; a microcontroller will be designed to control the operation mode of microplasma array and the data acquisition to decrease the power consumption and cost; and lock-in imaging technique and heterodyne detection technique will be developed to increase signal-to-noise ratio. Using these techniques, we will develop a THz imaging array based on microplasam with the array format of 320×240，the power consumption of less than 0.1 W, the responsivity of larger than 5000 V/W, the noise equivalent power of less than 1 pW/Hz^(1/2), imaging speed of 10 frames/second, the spectral range of 0.1-10 THz and room operation. The proposal will not only improve the application of THz real time imaging technique, but also push the investigation on microplasma.