光声光谱是基于光声效应发展起来的具有灵敏度高、适应性强、应用范围广的一种新颖的光谱测量技术,在对不透明物、高反射、高散射性物质的研究及对分子激发态驰豫过程包括禁戒跃迁的研究、膜和催化剂表面结构及吸附作用的研究、光化学和环境监测分析等方面的研究中得到了广泛的应用。尤其是在材料科学、生物医学等领域显示出其优越性。然而,我们在测量绿叶等植物样品时出现了非唯一的结果,本文针对这种情况提出采用正交锁定放大器来测量植物样品的光声光谱。 Photoacoustic spectroscopy is a novel spectroscopic technique developed based on photoacoustic effect with high sensitivity, strong adaptability and wide application range. In the research of opaque, highly reflective and highly scattering materials, The relaxation process has been widely used in the study of forbidden transitions, surface and adsorption of membrane and catalyst, photochemistry and environmental monitoring. Especially in materials science, biomedicine and other fields show its superiority. However, we have non-unique results when measuring plant samples such as green leaves. In this paper, we propose to use orthogonal lock-in amplifier to measure the photoacoustic spectrum of plant samples.