In most spectroscopic instruments (spectrographs, spectrometers, radiometers), calibration tubes are used either to set the wavelengths correctly(spectral calibration) or to quantify the intensity of the measured radiation(radiometric calibration).
Light sources for spectral calibration have a larger number of very narrow lines in the emission spectrum. Typical examples are low pressure lamps filled with a suitable gas or mixture of gases (Ne, Ar, Xe, Kr, Hg-Ar, Hg-Ne).
Radiometrically calibrated light sources emit radiation with a well-defined spectral irradiance (spectral irradiance [Wm-2nm-1]) and therefore allow so-called absolute calibration of the instrument.
Key features
- Compactness
- Affordability
- Excellent stability
- Wide selection (coverage of the entire UV-VIS-NIR region)
- Easy to tie into optical fiber (built-in connector or special adapter)
Types of calibration light sources
- Compact portable Pen-Ray lamps (spectral calibration)
- Lamps with robust protective housing and fibre output (spectral calibration)
- Radiometrically calibrated light sources (radiometric calibration)
