LRS Micro-g LaCoste FG5, Manual, Page: 66 / 149

Adjustment and Maintenance
4
4.1.1.11.Pumping Down the Dropping Chamber
See Appendix B for instructions on pumping down the dropping chamber.
4.2. The Interferometer
4.2.1.ALIGNMENT
1. Set up the superspring and attach the interferometer base as described in the
setup instructions.
2. Center the precision bubble vials mounted on the base of the superspring by
adjusting the leveling feet on the superspring tripod.
3. Turn on the laser.
4. Roughly collimate the laser beam on the ceiling or on a target above the
interferometer base. The collimating assembly is on the output end of the
laser fiber. Use a 2.5 mm Allen wrench to remove the collimating assembly
from the interferometer. Adjust the collimation of the beam by loosening the
locking screw (2.5 mm Allen screw) on the slide of the fiber input and moving
the slide. A properly collimated beam should have a diameter of 6 mm.
5. Slide the loosened assembly back into the interferometer (note the orientation
key) and precisely collimate the laser beam by use of the slide until the beam
size in the collimating telescope is minimized.
6. Tighten the locking screw on the slide. Then tighten the assembly into the
interferometer using the second Allen screw
7. Remove the dust plug on the top of the interferometer base and place the
dropping chamber tripod and dropping chamber on top of the interferometer
(see setup instructions).
8. If possible (both spots visible), verticalize the beam as described in the setup
instructions.
9. Slightly loosen the two screws directly above the fiber optic input on the
interferometer base, just sufficient to allow movement of the fiber optic input
stage.
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