HP 5501A Operating And Service Manual page 242

Table 6-4. English/Metric Pulse Output Electronics System Troubleshooting (Cont'd)
c) Intermittent measurement signal on one or more measurement axes may indicate:
'Use laser power meter frltered
CAUSE
1. Misalignment of
optical components
2. Misadjustment
of 10780A re-
ceiver gain
3. Low power in
frequency used
for measurement
4. 10780A mal-
function, cable
intermittent, or
10760A malfunc-
tion.
for
6328
Angstroms (e g. Unrted Detector Technology #40X meter (w/filter)
1.
CHECK
Reduce beam size by ro-
tating to small apera-
ture on laser head.
Place alignment target
on receiver lens. Move
optics along entire
measurement path and
verify both return
beams overlap on the
target along the entire
length of movement.
Monitor 10780A test
point on back of
receiver, voltage
should lie in range
0.5 - 1.OV dc. If volt-
age >I
.1V,
receiver
could be saturated.
If voltage <0.2V,
gain may be too low.
Use power meter, if
available, and polar-
izer and check rela-
tive power of hori-
zontal and vertical
polarization.*
Look at output sig-
nal from 10780 and in-
put of 10760.
ACTION
If optics are
misaligned and
beams do not
overlap, refer
to Section
I 1
for
alignment pro-
cedure.
Refer to 10780A
manual for ad-
justment pro-
cedure.
Rotate interfero-
meter 90 degrees
and look for in-
crease in test
point voltage.
Troubleshoot
appropriate
component