Newport Cornerstone 130B, User Manual

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90088262 MCS130B
CORNERSTONE 130B MONOCHROMATORS
37
11.3
47B
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/3.9). Note t hat
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 GRATINGnFA CTOR
command may also be used.
12. Repeat the process for the second grating, if required.
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
11.4
48B
ALTERNATIVE METHOD (CS130B ONLY)
Instead of noting the wavelength in step 7,
send the command “user:cal:lambda1 XXX.XXX”,
where the X’s represent the wavelength (in the currently selected units) observed at the output. In
step 9, send the second wavelength using the command “user:cal:lambda2 XXX.XXX”. The
CS130B will compute and store the new grating factor and offset.