DIAGNOSTIC TESTING METHOD FOR A SPECTROMETER

A diagnostic testing method for a detector of a spectrometer is provided. The spectrometer comprises a source of line spectra configured to emit at least one branched pair of spectral lines from an excited species. The diagnostic testing method comprises performing a plurality of detector diagnostic measurements and diagnosing an operating condition of the detector. Each detector diagnostic measurement comprises measuring an intensity of a first spectral line emitted by an excited species of the source of line spectra using the detector, and measuring an intensity of a second spectral line emitted by the excited species of the source of line spectra using the detector. The first and second spectral lines emitted by the excited species of the source of line spectra form a branched pair of spectral lines, and the spectrometer is controlled in order to vary the intensity of the first and second spectral lines incident on the detector for the plurality of detector diagnostic measurements. Diagnosing the operating condition of the detector is based on a ratio of the intensity of the first spectral line to the intensity of the second spectral line for each of the plurality of detector diagnostic measurements.