基于高速数字相关器的太赫兹干涉仪系统研究

Investigation on THz Interferometer System Based on High Speed Digital Correlator

干涉仪利用通道间的相关运算进行测量,是干涉式成像的基本单元。太赫兹成像在安全检查、军事侦查等方面有着广泛的应用前景。将干涉成像测量引入太赫兹领域后,为解决相关运算中高速信号的相位同步问题,该文提出基于低速FPGA控制的交叉同步方案,用低硬件代价解决高速采样信号的相位同步问题,并完成了一套多通道高速数字相关系统。系统的最高采样速率为5 GHz,ADC有效位数大于等于6位,相关器积分时间可调。最后,利用该数字相关器和相应的太赫兹微波元器件搭建了中心频率为0.44 THz的干涉仪,并得到了清晰的干涉条纹,其线性相位误差小于2?。该研究为今后设计太赫兹干涉成像仪提供了基本单元。

As a conventional unit in interferometric imager, correlator has a wide range of applications to get visibility functions. THz imager has more and more applied to security check and military scouting area. To solve the phase synchronization problem in high speed digital correlator, which is designed for THz interferometer, this paper presents a cross synchronization scheme based on low hardware cost FPGA controller. A high speed multichannel digital correlator is presented under this scheme. In this correlator, sampling rate can reach as high as 5 GHz, effective number of ADC is greater than or equal to 6 bit, integration time is adjustable. Interference fringes are presented by constructing a 0.44 THz interferometer out of this correlator and related THz microwave devices. The fringe＇s linear phase error is better than 2？. The research could provide important reference value about the design of THz interferometric imager in future.