MOGlabs MWM, Manual, Page: 34 / 96

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Chapter 4. MOGWAVE
Rel
When selected, the current wavelength is saved as a reference. The refer-
ence is subtracted from future measurements so the displayed wavelength
shows the change relative to the reference value.
4.6 Wavelength
Wavelength
The primary wavelength measurement is shown in a variable size
(stretchable) text window. The last digit is slightly smaller and in grey
text as a reminder that its value is imprecise. Click on the number to cycle
through the different units.
(nm, vac)
The in-vacuum wavelength, converted from the measured value using mea-
surements of the air pressure and temperature.
(nm, air)
The in-air wavelength, converted from the measured value using correc-
tions for pressure or temperature.
(nm, raw)
The raw in-air wavelength, as measured by the
MWM
, without corrections
for pressure or temperature.
(THz)
The frequency, converted from the measured in-air wavelength, using mea-
surements of the air pressure and temperature.
(cm
−
1 )
The wavenumber; that is, the number of wavelengths per cm, in vacuum,
converted from the measured in-air wavelength using measurements of the
air pressure and temperature.
Uncertainty/Width
Shows the peak width as an rms or full width at half maximum
(fwhm), or the statistical uncertainty of the wavelength measurement. Click
on the number to cycle through the options. The uncertainty is just a guide
to indicate the reliability of the measurement and should not be used for
quantitative purposes. The rms and fwhm widths are calculated assuming
a Gaussian peak shape.
The instrumental resolution width can be subtracted automatically, by
setting the
mwmwidth
value in the
default.cfg
file; see appendix E.