Molecules and atoms in a substance absorb or emit photons under the irradiation of light of a specific wavelength, generating characteristic spectra related to the structure and composition of the substance. The infrared laser light emitted by the 1064nm infrared laser diode is used as an excitation light source. After interacting with the substance, the composition, structure and other information of the substance can be obtained by detecting the spectral changes such as absorption, scattering or fluorescence of the substance.