HP 5501A Operating And Service Manual page 83

Y AXlS
BEAM
L
1
RETROREFLECTOR
BENDER
SINGLE BEAM INTERFEROMETER
Y
AXlS
RECEIVER
Y
AXlS
BEAM
RECElVER
X AXlS
SPLITTER
LINEAR
A ALIGNMENT SCHEMATIC
IIJTERFEROMETER
INTERFEROMETER
ALIGNMENT
POSITION 2
TO
0 ALIGNMENT TARGET FOR INTERFEROMETER RECEIVER , I N T E R F E R O M E T E R
FROM
INTERFEROMETER
C ALIGNMENT TARGET FOR RECEIVER
Figure
2-53.
Visual Alignment
5. Traverse the retroreflector to its furthest point (at least 0.5 metres (20 inches)).
6 . Adjust the laser head angularly to center the return beam on the receiver alignment
target.
7 .
Return the retroreflector to the closest point to the interferometer.
8. Repeat steps 4 through
7
until the return beam is centered on the receiver alignment
target at both ends of travel. An offset of 500 micrometres over a 0.5 metre travel is
equal to a cosine error of 0.5 parts per million or 0.5 microns per metre of travel (0.5
microinches per inch).
9. If the reference beam returning from the interferometer is not centered on the re-
ceiver alignment target, adjust the interferometer until both the reference and mea-
surement beams are centered.