PASCO SP-9268A STUDENT SPECTROMETER - Manual (Page 7)

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012-02135F Student Spectrometer
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Equipment Setup
NOTE: If you are using the optional Gaussian
Eyepiece (SP-9285), equipment setup is somewhat
simpler than described below. See the Appendix
for instructions.
Leveling the Spectrometer
For accurate results, the diffracting element must be
properly aligned with the optical axes of the telescope
and collimator. This requires that both the spectrometer
and the spectrometer table be level.
1. Place the spectrometer on a flat surface. If necessary
use paper or 3 X 5 cards to shim beneath the wood
base until the fixed-base of the spectrometer is level.
2. Level the spectrometer table by adjusting the three
thumbscrews on the underside of the table.
Focusing the Spectrometer
1. While looking through the telescope, slide the eye-
piece in and out until the cross-hairs come into sharp
focus. Loosen the graticule lock ring, and rotate the
graticule until one of the cross-hairs is vertical. Re-
tighten the lock ring and then refocus if necessary.
2. Focus the telescope at infinity. This is best accom-
plished by focusing on a distant object (e.g.; out the
window).
3. Check that the collimator slit is partially open (use
the slit width adjust screw).
4. Align the telescope directly opposite the collimator
as shown in Figure 3.
5. Looking through the telescope, adjust the focus of
the collimator and, if necessary, the rotation of the
telescope until the slit comes into sharp focus. Do not
change the focus of the telescope.
6. Tighten the telescope rotation lock-screw, then use
the fine adjust knob to align the vertical line of the
graticule with the fixed edge of the slit. If the slit is
not vertical, loosen the slit lock ring, realign the slit,
and retighten the lock ring. Adjust the slit width for a
clear, bright image. Measurements of the diffraction
angle are always made with the graticule line aligned
along the fixed edge of the slit, so a very narrow slit
is not necessarily advantageous.
NOTE: When the telescope and collimator are
properly aligned and focused, the slit should be
sharply focused in the center of the field of view of
the telescope, and one cross-hair should be perpen-
dicular and aligned with the fixed edge of the slit.
If proper alignment cannot be achieved with the
adjustments just described, you will need to re-
align the spectrometer as follows.
Realigning the Spectrometer
Under normal circumstances, the spectrometer will main-
tain its alignment indefinitely. However, if the spectrom-
eter can not be properly focused, as described above, it
may be necessary to adjust the optical axes of the colli-
mator and telescope, as follows:
1. The telescope and collimator pivot about a fulcrum
on their respective mounting pillars (See Fig 4). Use
the aluminum rod provided with the accessory equip-
ment to adjust the leveling screws. Loosen one as the
other is tightened until the unit is level and secure.
LEVELING
SCREWS
FULCRUM
MOUNTING
PILLAR
Figure 4 Leveling the Telescope and Collimator
Figure 3 Align the Telescope directly opposite
the Collimator
COLLIMATOR
TELESCOPE