基于迈克尔逊干涉仪的太赫兹光谱高速探测方法研究

太赫兹光谱技术作为获取物质在太赫兹频段信息的主要方法，已经被广泛应用于物质成分的测定，而其在成分分布成像方面则有着更广阔的应用前景，例如片剂药品的有效成分检测、行李安检的危险物品检测等。现有的太赫兹光谱探测方法时域光谱技术（THz-TDS）和频域光谱技术（THz-FDS）均不能很好地兼顾光谱分辨率与扫描时间；且获得物质光谱数据往往要花费数秒乃至数分钟时间（取决于光谱仪的结构），这对多像素成像系统显得过于迟缓，更无法达到视频成像的速率需求，严重制约了太赫兹光谱成像的实际应用。目前的太赫兹波成像多为全频段波强度成像，只能反映样品的空间分布信息，并不能反映出样品的光谱即成分信息。因此，对太赫兹光谱探测速率的提升十分迫切，太赫兹光谱高速探测的实现不仅可以显著减少物质成谱的实验耗时，还为实现物质的太赫兹光谱成分分布成像提供了可能。提出了一种基于迈克尔逊干涉仪的太赫兹光谱高速探测方法，在设计了该方法装置结构的基础上，理论分析了其工作过程，同时进行了太赫兹光谱的计算。然后从数据采样、数据处理及参数选择这几个方面进行问题分析，计算得出该方法能够显著加快物质太赫兹光谱的扫描获取速率。最后，对该方法建模进行仿真研究，模拟实现其完整的探测过程。在仿真研究中，以太赫兹辐射源的频谱分布为例，将该方法的建模仿真结果与时域光谱技术（THz-TDS）测试结果进行了对比，结果表明时域光谱技术（THz-TDS）所测得的频谱曲线可以近似看作是该高速光谱探测法所得频谱曲线的包络线，两种不同方法所得频谱结果具有较强的一致性。总之，该方法能够进行样品的太赫兹光谱探测，且在保证分辨率相同的前提下，较时域光谱技术（THz-TDS）显著加快了成谱速率，为实用、高通量太赫兹光谱成像提供了一种可能。

Study on High Speed Detection of Terahertz Spectrum Based on Michelson Interferometer

Terahertz spectroscopy, as the main method to obtain the information of substances in terahertz frequency band, has been widely used in the determination of substance composition, and it has a broader application prospect in the imaging of composition distribution, such as the detection of effective components of tablets and drugs, the detection of dangerous goods in baggage security inspection and so on. The current terahertz spectral detection methods, time-domain spectroscopy (THz-TDS) and frequency-domain spectroscopy (THz-FDS), can’t take account of both spectral resolution and scanning time well, and it often takes several seconds or even minutes (depending on the structure of the spectrometer) to obtain spectral data, which makes the multi-pixel imaging system appear to be overdone. The application of terahertz spectroscopic imaging is seriously restricted because of the delay and the inability to meet the speed requirement of video imaging. At present, terahertz imaging is mostly full-band intensity imaging, which can only reflect the spatial distribution information of the sample, but can’t reflect the spectral information of the sample. Therefore, it is very urgent to improve the detection rate of terahertz spectroscopy. The realization of high-speed detection can not only greatly reduce the time-consuming of spectroscopy experiment, but also provide the possibility to realize the terahertz spectroscopic composition distribution imaging. In this paper, a high-speed detection method of terahertz spectrum based on Michelson interferometer is proposed. On the basis of designing the structure of the device, the working process is analyzed theoretically, and the terahertz spectrum is calculated. Then, the aspects of data sampling, data processing and parameter selection are analyzed, and the results show that the method can significantly speed up the acquisition rate of THz spectra. Finally, the method is modeled and simulated, and the whole detection process is simulated. Taking the spectrum distribution of terahertz radiator as an example, the simulation results of this method are compared with the test results of time domain spectroscopy (THz-TDS). It is found that the spectrum curve measured by time domain spectroscopy (THz-TDS) can be approximately regarded as the envelope of the spectrum curve obtained by this high-speed spectral detection method. The results have strong consistency. This shows that the proposed method can detect the terahertz spectra of samples, and it can significantly accelerate the spectral formation rate compared with the time-domain spectroscopy (THz-TDS) on the premise of the same resolution. It provides a possibility for practical and high-throughput terahertz spectroscopy imaging.