PASCO OS-9171 User manual

Instruction Sheet
Aligning the PASCO Model OS-9171 Laser with the
OS-9172 Alignment Bench
The Helium Neon Laser
The helium neon laser is a 0.5 mW, TEM00 mode laser,
providing randomly polarized light at a wavelength of 632.8
nm. The built-in power supply is regulated so the output has
minimum ripple and the intensity is stable to within ±2.5%.
A 15 minute warm up is required to reach full power, but the
power on start-up is greater than 0.35 mW. If you'd like
more technical specifications, and a detailed explanation of
laser operation, see the instruction manual that's included
with the laser.
Caution: This is a relatively safe, low power
laser. Nevertheless, we strongly recommend the
following precautions:
1. Never look into the laser beam, either directly, or
as it is reflected from a mirror.
2. Set up experiments so the laser is either above or
below eye level (for both sitting and standing
people).
To Set Up the Laser using the Laser Alignment
Bench:
The laser is most conveniently aligned using the laser
alignment bench, which can be joined to the optics bench
using the bench couplers. The procedure is as follows:
1. Place the optics bench and the laser alignment bench
end to end, as shown in Figure 1. Notice that only one
end of the laser alignment bench has holes for two
leveling screws. That is the end that joins to the optics
bench.
2. Remove the four leveling screws on the adjoining ends
of the two benches.
3. Use the 1/4-20, hex-head screws that are included with
the bench couplers to attach the couplers to the legs of
the benches, as shown. Do not yet tighten the screws.
4. Insert one of the leveling screws, rubber foot down,
through the threaded hole in each coupler.
Figure 1 Connecting the Laser Alignment Bench
Laser
alignment
bench
Top View of Bench Coupler
Bench coupler
Leveling Screw
and lock-nut
1/4 20
hex-head
screw
Optics
bench
Optics bench
012-01562C
9/91
$1.00
Bench coupler
(one each side)
Laser alignment bench
Leveling screw

scientific
2
012-01562C
5. By adjusting all five leveling screws (one on the laser
alignment bench, two on the optics bench, and two on
the bench couplers), align the two benches so they are in
a straight line. Use a meter stick or a long straight edge
on top of the benches to check vertical alignment, and
on the side of the bench to check horizontal alignment.
6. When the benches are aligned, tighten the lock-nuts on
all the leveling screws, and also tighten the four hex-
head screws. After tightening the screws, recheck the
alignment.
To Align the Laser (so the laser beam is coincident
with the optical axis of the bench):
1. Place a piece of masking tape or tape a piece of paper
over the square hole on the front of a component holder,
as in Figure 2. Make a small dot on the tape or paper, in
the center of the square hole (1-inch from the top of the
component shelf, and 1.5-inch from the edge of the
component holder).
2. Place the laser on the alignment bench, as in Figure 3.
Center the laser on the bench, and make sure it is
reasonably parallel with the bench.
3. Place the component holder on the optics bench, about
10 cm from the laser aperture. Make sure that the
component holder is flush against the alignment rail of
the bench. The dot on the tape now marks the optical
axis of the bench.
4. Turn on the laser, and move the aperture end of the laser
sideways, as needed, so that the laser beam falls on the
dot.
1.5"
Figure 2 Locating the Optical Axis
5. Move the component holder about 90 cm away from the
laser aperture. Again, be sure the edge of the compo-
nent holder is flush against the alignment rail of the
bench.
6. Without moving the aperture end of the laser, move the
rear end of the laser as needed to recenter the laser beam
on the dot. (You may also need to adjust the leveling
screws on the laser alignment bench in order to center
the laser beam vertically on the dot.)
7. Repeat steps 3 through 6 until the laser beam is aligned
with the dot for both positions of the component holder.
Alignment bench
Figure 3 Aligning the Laser
Tape
or
paper
Laser
Dot
1"
Component
holder with
alignment dot
Optics bench