HP 5528A

ModelSS28A
First look
9. Put a piece of paper between the Interferometer and the Retroreflector so you block the
beam.
looking at the front of the laser Head, you s hould see one dot disappear as you do this. This
will be the Retroreflector's return beam. The dOl thai remains is the Interferometer's return
beam.
10. Adjust the Interferometer's position, vertically and horizontally, until its return beam is
ce ntered on the return port 's target.
11 . Adjust the Relroreflector's position, vertically and horizontally, until its return beam is also
centered
on the return port's target.
You s hould now see only one dot on the return port's target, since both return beams s hould
overlap co mpletely .
12. Turn both the ret urn port 's and the exit port's aperture controls to fully open both ports.
look at the BEAM STRENGTH meter on the Measurement Di sp lay or the Remote Control
unit.
You should see the meter's needle move into the "green" area.
13 . Move the Retroreflector slightly to one side.
Note how the BEAM STRENGTH indication changes as you do this.
You should note a decrea se in beam strength whenever you see the beam being clipped by
the
laser Head's return port. (i.e., Any part of the beam that does not enter the return pori is
lost, as far as co ntributing to the measurement.)
14 . Move the Retroreflector over the full length of the pattern s hown on the template that was
provided as Figure 2~5.
N OTE
Be su re to keep t he Retroreflector 's base flush against the
straightedge
as you do thi s.
Watch the BEAM STRENGTH meter while you do thi S. Make sure its needle sl ays in the green
area.
If the BEAM STRENGTH needle doe sn't s tay in the green area, move the straightedge at that
point so thai the BEAM STRENGTH needle moves back into the green area. Beam strength
must be kept in the green area along the
full di stan ce of Retroreflec tor movement ( 60 mm
(
2.4 inches)).
You have just a li gned the Optic's path to the la se r beam. In actual practice, you will il li gn the
la ser beam (by adjusting the laser Head) to match the Opti c 's path. In any measurement you
make with the Laser Meas urement System, you will have to align the la se r Head to the
Optic's or the ma chine's travel path to return as much signal as possible to the la ser Head's
return port .
For Distance and
Velocity measurement s, alignment is also important for reducing
some
thing ca lled "cosine error". ( See " WHAT AFFECTS ACCURACY?" in Se ction 6 .)