Frequency shift due to Field of View
Appendix E FTIR Frequency scale calibration
64
AA003700-01 rev. G. 2.0
view defining positions for the MB3000. The source is a SiC glowbar with a 3 x 3
mm hot emitting area.
Frequency shift due to Field of View
The frequency scale of an FTIR is highly linear. Hence the frequency scale can be
calibrated with one reference frequency realizing that zero frequency is always
fixed. A quick verification of the frequency calibration of an FTIR is to measure a
raw spectrum of ambient air where fine absorption lines indicate the presence of
water vapor. At a resolution of 1 cm
-1
, two individual water vapor spectral lines
have been identified for calibration verification. These are the lines at 1918 cm
-1
for
mid IR and 7300 cm
-1
for Near IR
Table 10.
Location
Magnification
Size limit
FOV limit
source focal plane
1
1x 2.5 mm
partial limiting
output focal plane
2
3.1 mm
partial limiting
sample beam focal plane
2.8
sample
accessory dependent
detector focal plane
0.467
1 mm
not limiting
Table 11.
location
magnification
size limit
FOV limit
source focal plane
1
3 x 3mm
not limiting
output focal plane
2
4.5 mm
limiting
sample beam focal plane
2.8
sample
accessory dependent
detector focal plane
0.467
1 mm
not limiting
