7.3 Wavelength Calibration Procedure
Calibrate the wavelength of excitation and emission wavelength using the 0-order light of the low-
pressure Hg (Mercury) lamp, 253.7 nm (1-order light), 507.3 nm (2-order light) and 761.0 nm (3-order
light) of the emission line. When "FACTORY" - "WAVE ADJ" is executed, the wavelength is calibrated
in the following order. While wavelength calibration is being executed "CALIBRATING SPAN" is
displayed. After wavelength calibration ends, the wavelength accuracy is checked automatically.
1. Detection of grating home position
The spectrophotometer determines the wavelength referenced to the grating home position. First,
the home positions of the grating on the excitation and emission sides are automatically detected.
2. Movement of the excitation-side grating to the position near 254 nm
The excitation-side grating is gradually rotated from near 250 nm slightly below 254 nm for the
low-pressure Hg (Mercury) lamp, and the light intensity peak is recorded by the excitation-side
light sensor.
3. Movement of the emission-side grating to the 0 nm position
The excitation-side grating is aligned with the 254 nm position determined in 2.
Next, the emission-side grating is gradually rotated from near -10 nm slightly below 0 nm for the
low-pressure Hg (Mercury) lamp, and the light intensity peak is recorded by the emission-side
light sensor.
4. Calculation of rotation angle required for movement of the emission-side grating to the
0 nm position
The rotation angle required for movement of the emission-side grating to the 0 nm position from
the home position is calculated.
5. Movement of the emission-side grating to the position near 254 nm
The emission-side grating is gradually rotated from near 250 nm slightly below 254 nm for the
low-pressure Hg (Mercury) lamp, and the light intensity peak is recorded by the emission-side
light sensor.
6. Calculation of rotation angle required for movement of the emission-side grating to the
254 nm position
The rotation angle required for movement of the emission-side grating to the 254 nm position
from the home position is calculated.
7. Movement of the excitation-side grating to the 254 nm position
The emission-side grating is aligned with the 254 nm position determined in 5. Next, the
excitation-side grating is gradually rotated from near 250 nm slightly below 254 nm for the low-
pressure Hg (Mercury) lamp, and the light intensity peak is recorded by the emission-side light
sensor.
8. Calculation of rotation angle required for movement of the excitation-side grating to the
254 nm position
The rotation angle required for movement of the excitation-side grating to the 254 nm position
from the home position is calculated.
9. Movement of the excitation-side grating to the 0 nm position
The emission-side grating is aligned with the 254 nm position determined in 5. Next, the
excitation-side grating is gradually rotated from near -10 nm slightly below 0 nm for the low-
pressure Hg (Mercury) lamp, and the light intensity peak is recorded by the emission-side light
sensor.
10. Calculation of rotation angle required for movement of the excitation-side grating to the
0 nm position
The rotation angle required for movement of the excitation-side grating to the 0 nm position from
the home position is calculated.
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