PASCO OS-8539 Educational Spectrophotometer - Manual (Page 14)

®
E d u c a t i o n a l S p e c t r o p h o t o m e t e r A c c e s s o r y K i t a n d S y s t e m S e t U p
10
Mounting the Grating
The Grating is mounted on one side of a rectangular glass plate.
There are two magnetic pads on the same side of the glass plate as
the Grating. These pads hold the Grating in place on the Grating
Mount.
Once the light from the source is collimated, attach the Grating to
the Grating Mount so that the glass side of the Grating faces the
light source (Fig. 18).
Mounting and Positioning the Focusing Lens
The Degree Plate has markings on either side of the Light Sensor
Arm that indicate the approximate position in which to place the
Focusing Lens. The Focusing Lens has two small magnets in its base that hold it in place on top of the Light Sen-
sor Arm. Place the Focusing Lens on the Light Sensor Arm between the Grating Mount and the High Sensitivity
Light Sensor.
The Focusing Lens focal length is about 10 cm so the
lens should be positioned on the Light Sensor Arm
about 10 cm from the front of the Aperture Disk (Fig.
19).
Set up the light source, Collimating Slits, and Colli-
mating Lens so a beam of light shines through the
Grating and Focusing Lens. Darken the room so you
can see the spectral lines more clearly. Move the
Light Sensor Arm so the central ray of light (called
the “zeroth order”) is centered on the slit at the bot-
tom of the Aperture Disk. You should be able to see
the first order spectral lines on the Aperture Screen
on either side of the central ray of light. Adjust the
position of the Focusing Lens until the spectral lines
are sharply focused.
Note: Because the Grating is strongly blazed, the spectral lines on one side of the central ray (“zeroth order”) will
be less bright than the spectral lines on the other side.
Caution! Handle the Grating carefully. Avoid touching the Grating or the glass plate
to which the Grating is attached except by the edges of the glass plate.
Glass side faces light source
Grating Mount
Grating
Figure 18: Grating onto Mount
10 1 10 0
GA IN
HIGH
SENSITIVITY
LIGHT SENSOR CI-6 60 4
Figure 19: Position Focusing Lens
Grating
Focusing Lens
Aperture Screen
Aperture Disk