
84 1100 Series DAD and MWD Reference Manual
3 Troubleshooting and Test Functions
Wavelength Recalibration
The detector uses the alpha (656.1 nm) and beta (486 nm) emission lines of the
deuterium lamp for wavelength calibration. The sharp emission lines enable
more accurate calibration than is possible with holmium oxide. When
calibration is started, the 1-nm slit is moved into the light path automatically,
and the gain is set to zero. To eliminate effects due to absorbing solvents, the
test should be done with water in the flow cell. After calibration, the holmium
oxide test (see Figure “Holmium Oxide Test” on page 86) provides verification
of wavelength accuracy at three additional wavelengths. Wavelength
calibration should be done after maintenance of the flow cell, lamp exchange,
or after major repair, like processor board or optical unit exchange, see also
“Replacing the Detector’s Firmware” on page 180.
Figure 20 Wavelength Calibration
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