Absolute calibration of LIBS data

The spectroscopic results are commonly expressed in “counts” unit; however, these “counts” are calculated by inner hardware/software procedures and cannot be regarded as a number of events of photon emission or even their interaction with detectors. The “counts” number depends on many factors as the camera spectral sensitivity and transmittances of all the optical components between plasma under observation and the detector.

On the other hand, quantitative spectral analysis of the emitted photons is an inevitable step in the development of the calibration-free LIBS method, therefore, a conversion of the inner spectrometer units into the acts of emissions needs to be performed. It can be carried out by means of a light source of a known spectral distribution for which the calibration functions can be derived.

In the article, the results of the research regarding this issue and the methods for finding the necessary parameters are discussed. As the source of known spectrum tungsten-deuterium lamp is used. The calibration function have been derived for different ICCD gain settings. Finally, the complete model of the measurement setup is derived, which may be applicable in various fields, aiming at calibration-free LIBS.