MCS260B
CORNERSTONE 260B MONOCHROMATORS
37
11.3 DETERMINING THE GRATING CALIBRATION FACTOR
The following procedure allows advanced users to perform a two-point grating calibration.
Procedure:
1. Select a radiation source that has at least two narrow spectral lines in the wavelength region of
interest.
2. Select a detector with an operating range appropriate for the spectral lines.
3. Focus the radiation onto the entrance slit (the monochromator is F/3.97). Note that a narrower
slit provides greater resolution.
4.
Ensure the focused beam is parallel to the monochromator’s optical axis.
5. Command the monochromator to select the grating to be recalibrated.
6. Use the STEP command to move the grating position until the first spectral line is visible at the
output.
7. Note the wavelength at which this first spectral line peak appears.
8. Use the STEP command to move the grating position until the second spectral line is visible at
the output.
9. Note the wavelength at which this second spectral line peak appears.
10. Use the formula to calculate the new Grating Factor.
11. Use the utility software to enter the new Grating Factor. The GRATINGnFACTOR command
may also be sent to the monochromator.
12. Repeat the process for the second, third, and fourth gratings, if required. Depending on the
configuration, the monochromator may have two or four gratings installed.
Spectral Line
Observed Peak
Wavelength 1
Wavelength 2
FACTOR = | L1
– L2 | / | P1 – P2 |
Example:
Spectral Line
Observed Peak
Wavelength 1
546
577
Wavelength 2
365
372
FACTOR = |546
– 365| / |577 – 372| = 181 / 205 = 0.8829268
