spectral invariant

例句：

1. 1. The spectrum of the light reflected from the surface is used to determine its chemical composition.
   从表面反射的光的光谱用于确定其化学成分。
2. 2.Spectral analysis is a powerful tool for studying the properties of materials.
   光谱分析是一种研究材料特性的强大工具。
3. 3. In the study of astronomy, spectral lines are used to identify and analyze different types of stars.
   在天文学研究中，光谱线被用来识别和分析不同类型的恒星。