Plane Mirror Interferometer - HP 5501A Operating And Service Manual

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X-Y STAGE
X AXlS
PLANE MIRROR
-tx
Y
INTERFEROMETER
MIRRORS
VOLTMETER
J
I
t
-
X AXlS
1'
Y AXIS LASER BEAM
LASER
Y AXlS
6096 PLANE MIRROR
BEAM SPLITTER
w
INTERFEROMETER
Y AXlS
Figure 2-55. Plane Mirror Interferometer Alignment
NOTE
Steps 1 through 10 constitute the Y-axis alignment.
1.
Place the interferometer alignment target on the laser side of the Y-axis plane mirror
interferometer and the receiver alignment target on the receiver (Figure 2-53c,
position 1). Place a piece of opaque material between the Y-axis plane mirror inter-
ferometer and the mirror.
2. Adjust the laser head until the laser beam passes through the 50% beam splitter, enters
one hole of the interferometer alignment target and exits the other centered on the
receiver alignment target. Lock down the laser head securely.
3. Select the small aperture of the front turret of the laser head and install the alignment
aid on the output of the plane mirror interferometer in the correct orientation. Re-
move the opaque material from between the plane mirror interferometer and the
mirror.
4. The laser beam will now exit the interferometer and be reflected by the mirror upon
itself back into the interferometer. Angularly adjust the plane mirror interferometer
until the beams reflected from the mirror returns through the plane mirror interfero-
meter and back to the small aperture of the laser head. Slight lateral adjustments of the
plane mirror interferometer may be required to ensure that the reference beam is
still centered on the receiver alignment target. If the distance between the mirror and
the laser head is at least 0.5 metres (20 inches) then the formula given in the section on
Visual Alignment determines the cosine error based on the offset of the return beam
at the laser head.