红外光谱仪是利用物质对不同波长的红外辐射的吸收特性，进行分子结构和化学组成分析的仪器。红外光谱仪通常由光源，单色器，探测器和计算机处理信息系统组成。根据分光装置的不同，分为色散型和干涉型。对色散型双光路光学零位平衡红外分光光度计而言，当样品吸收了一定频率的红外辐射后，分子的振动能级发生跃迁，透过的光束中相应频率的光被减弱，造成参比光路与样品光路相应辐射的强度差，从而得到所测样品的红外光谱。
Infrared spectrometer is an instrument that analyzes the molecular structure and chemical composition by using the absorption characteristics of different wavelengths of infrared radiation. Infrared spectrometer is usually composed of light source, monochromator, detector and computer processing information system. It can be divided into dispersion type and interference type. For the dispersive two-way optical null balance infrared spectrophotometer, when the sample absorbs infrared radiation of a certain frequency, the vibrational energy level of the molecule transitions, and the light of the corresponding frequency in the transmitted beam is weakened, resulting in the difference in the intensity of the corresponding radiation between the reference optical path and the sample optical path, so as to obtain the infrared spectrum of the sample.