ABB MB3000 Series Installation And User Manual page 68

Technical background:
At factory, each solid state laser needs to have it wavelength calibrated. Since the
laser is used in an FTIR, there is no need to adjust the temperature and/or current to
get the same wavelength for all lasers. Instead, the same temperature and current
settings are always used and the wavelength is measured: This provides greater
reliability since it is not needed to push the temperature or the current to high levels
to get the same wavelength.
There are a number of ways to calibrate solid state lasers. The goal is to calibrate the
solid state lasers to the same accuracy or better than the He-Ne laser. The best way
to do this is to measure a known spectral line and adjust the laser wavelength in
software such that the measured line falls on its exact wavelength. For this a built-in
cell with a reference vapor and a separate source and detector is used. The
wavelength of the laser is stable for an extended period of time. However the
firmware in the spectrometer keeps track of the elapsed time and schedules a short
calibration procedure automatically every two weeks. The reason for this frequency
of calibration is that there is a small frequency shift due to aging of the laser. This
aging effect is expected to be quite small and would require recalibration only every
few months to stay within specification.
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Appendix D Calibration Transfer from FTLA to MB3000
AA003700-01 rev. G. 2.0