Optical emission spectrometers (often called "OES or spark discharge spectrometers"), are used to evaluate metals to determine the chemical composition with very high accuracy.OverviewA spectrometer is a scientific instrument used to separate and measure components of a physical phenomenon. Spectrometer is a broad term often used to describe instruments that measure a continuous. (often simply called "spectrometers"), in particular, show the intensity of as a function of wavelength or of frequency. The different wavelengths of light are separated by in a or by.