Thermo Scientific Omni FTIR Multi Gas CEMS Instruction Manual page 133

Thermo Fisher Scientific
Note Once the first objective mirror is positioned to get the beam in its
proper position on the field mirror, this mirror should NOT be readjusted
in any of the following steps.
9. Adjust the field mirror to get the image centered on the second
objective mirror (Figure
mirror are behind the mirror and are fitted with 11/32 nuts so they can
be adjusted from the sides. Use a small open end wrench to access
them.
10. Once the image is aligned on the center of the second objective mirror,
adjust the second objective mirror to get the exiting image positioned
in the field mirror cutout at the same position as the incoming beam
(in the cutout in front of the input window). These positions are shown
in Figure 5–38.
11. The cell gas should at this point be adjusted for minimum pass. Turn
the pass adjustment screw (horizontal adjustment of the second
objective mirror) clockwise to increase the number of passes. Observe
the two rows of images that appear on the surface of the field mirror.
These two rows should be parallel so the exiting image remains at the
proper position as the passes are adjusted. If the rows are not parallel,
adjust the tilt adjustment screw (top screw) on the second objective
mirror to get them parallel. This should also reposition the exiting
image so it is in the proper position as shown earlier in
The pass adjust screw may need to be readjusted some to keep a beam
exiting as you alter the vertical adjustment. Continue increasing passes
while adjusting the vertical position of the second objective mirror until
the maximum number of passes is obtained with the images remaining
parallel on the field mirror and the exiting beam properly positioned in
the output field mirror cutout. For the 5.2 meter gas cell, the
maximum number of passes should be 20, with the number of 5 images
on the bottom row as shown in
Preventive Maintenance and Servicing
▲
5–33). The adjustment screws on the field
Figure 5–40.
Omni FTIR Multi Gas CEMS Instruction Manual
Gas Cell Alignment
Figure 5–38.
5-49