太赫兹时域光谱技术可以分辨化合物结构上的微小差异并应用于物质检测与分析，为有机化工产品的鉴别及更宽有效光谱区的测试提供了新的实验方法.本文运用太赫兹时域光谱技术研究了甲醇、防冻液和刹车油在太赫兹波段的光学特性，在室温氮气环境中,得到了样品的时域谱和在0.2~2.5 THz波段的吸收谱.甲醇和防冻液、刹车油在此波段的吸收谱存在显著差异，甲醇的吸收峰位于0.35 THz、0.72 THz处，防冻液和刹车油的主要吸收峰位于0.62 THz处.实验表明，用太赫兹时域光谱技术可以检测防冻液和刹车油里是否掺有甲醇，进而判断其质量的优劣.

Terahertz time-domain spectra technology can distinguish minor differences in structure and can be applied to physical testing and analysis.It provides a new experimental method for the identification of the organic chemical products and the study of spectrum more wide.In this paper,the optical property and spectroscopy of methanol,anti-freeze liquid and brake fluid are studied based on the terahertz time-domain spectra in the terahertz range.At room temperature,the time-domain spectra and the absorption spectrum in the 0.2~2.5 THz region of these samples are obtained in the environment full of nitrogen.Methanol,anti-freeze liquid and brake fluid have significant different absorption spectra in this wave band.The absorption peaks of methanol are located at 0.72 THz and 0.35 THz and the main absorption peaks of anti-freeze liquid and brake fluid are located at 0.62 THz.Experiment results show that whether methanol exists in anti-freeze liquid or brake fluid can be detected using THz-TDS terahertz time-domain spectra technology and then its quality can be judged.