The commonly used instrument is called spectrometer, which is a small and simple spectrometer, mainly used for qualitative and semi-quantitative analysis of alloy steel and non-ferrous metal alloys. It consists of dispersion element, slit, collimator and objective lens. After the light source radiation is dispersed by glass prism or grating, the spectral line is focused on the eyepiece of the focal plane to read the spectrum and make visual measurement.

Spectrometers can be divided into two categories: classical spectrometers and new spectrometers. Classical spectral instruments are instruments based on the principle of spatial dispersion; The new spectral instrument is based on the modulation principle.