Research Of Terahertz Fourier Spectroscopy System

Terahertz radiation usually refers to the electromagnetic waves which frequency are within the range from 0.1THz to 10 THz,it is between the microwave and far infrared.Terahertz detection technology and spectral technology are important areas of terahertz research.In order to detect the small THz signal and perform the terahertz spectrum analysis,based on the basic principle of Michelson interferometer and Fourier transform theory,this paper update an old Fourier transform spectrometer in the laboratory from hardware and software,and call it Terahertz Fourier transform spectrometer(THz-FTS).The structure of the THz-FTS is simple,the working bandwidth is wide,the system control,data acquisition and processing are realized the automatic operation.It is convenient and fast to do data acquisition work,and has the broad application prospect.The THz-FTS uses a detection method which consist of the chopper,lock-in amplifier and Golay cell detector to detect terahertz signal.The method filters out the background thermal noise which generated on the way of signal transmission,improves the capability of THz-FTS to detect small terahertz signal.Writing control systems,data acquisition and data processing LabVIEW programs in LabVIEW development environment.Collecting the interference pattern data which interference signal amplitude varies with the optical path difference,and the spectral information of the signal is restored by the data processing program.The collected interferogram agrees with the theoretical analysis,and the spectral distribution of the broadband terahertz signal is restored,which proves the correctness of each part of the program.The parameters such as chopper rotating speed,the moving speed of moving mirror and sampling interval are changed in experiment to analyze the influence of these parameters.By reducing the intensity of the terahertz signal,this paper compares the ability of detecting the small THz signal between new system and original system.This paper use terahertz Fourier transform spectroscopy system to detect the spectrum of the terahertz wave contained in the He-Ne laser,and prove the practicability of the terahertz Fourier transform spectroscopy system.