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WinSpec/32 Manual
Version 2.5.C
7. Press Continue to initiate another Adjust computation cycle. The reported error
should decrease. Repeat the cycle two or three times – until no further reduction in
the error can be achieved. The final error value achieved may wander a bit with each
cycle repetition, reflecting the noise content of the spectrum.
8. Click OK to close the Adjust dialog box and return you to the Spectrograph
Calibrate dialog box.
Dispersion
Now that Offset and Adjust are complete, the spectrograph can move a target peak very
close to the center of the display. The final step is to calibrate the wavelength scaling so
that peaks on the far left or the far right in the window are also accurately calibrated.
This is called the Dispersion calculation, and again it is automated in WinSpec/32.
To adjust the Dispersion calculation you will make two measurements in the lower
spectral range (253.652 for Mercury); one measurement with the peak at the left edge of
the display and one with the peak at the right edge. Then you will make two
measurements in the upper spectral range (579.066 for Mercury). After these steps,
WinSpec/32 then tries to find the combination of Focal Length, Inclusion Angle, and
Detector Angle that minimizes the error.
Note: Some CCDs have very little response at 253.652. If this is the case for your
detector, it will be necessary to use a peak having a longer wavelength as the low value.
For mercury, the 435.833 line should prove suitable.
1. Click on the Dispersion button to open the
Dispersion dialog box. If you have never
calculated the Dispersion before, click on the
Default button. This provides standard values
for Focal Length, Inclusion Angle, and
Detector Angle based on the manufacturer’s
data for the active spectrograph. If you have
already run the Dispersion calculation before
and it provided satisfactory values, they will
be displayed and should be used as your
starting values.
2. Enter the Lower and Higher Reference
Wavelengths. For the mercury spectrum, use
253.652 (low) and 579.066 (high). Again, if
your CCD doesn’t have sufficient response to
calibrate at 253.652, it will be necessary to
use a different peak. It isn’t necessary to enter
a Target Wavelength. It will be calculated
during the procedure.
Figure 71. Dispersion dialog box