Optical spectrometry refers to analysing a light spectrum that consists of different wavelengths. Optical spectrometry can be devided into absorption and emission optical spectrometry. An optical emission spectrometer (OES) is an instrument that is made for projecting and analysing an optical spectrum, which is obtained by an excited sample. Exciting the atoms of the sample can be acquired by a handful of applications, like a spark, a plasma, a flame etc. This being said, these days the term OES predominantly refers to the technique spark optical emission spectrometry.
Spark Optical emission spectrometry involves applying electrical energy in the form of a spark generated between an electrode and a metal sample. The atoms and ions contained in the atomic vapor are brought to a high energy state within a so-called "discharge plasma" and are excited into emission of radiation. The radiation emitted is passed to the spectrometer (arc spark OES) optical system, where it is dispersed into its spectral components by a grating. From the range of wavelengths emitted by each element, the most suitable line for the application is measured by means of a chip (CCD / CMOS) or a photomultiplier.
Be sure to read my whitepaper that delves deeper into the fundamental principles of OES, the differences between the measurement techniques used and the motivation of Metal Spark for choosing the spark OES technique.