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36 ST-133 Controller Manual Version 3.B
Hint: Overhead fluorescent lights produce a mercury spectrum. Use a white card
tilted at 45 degrees in front of the entrance slit to reflect overhead light into the
spectrograph. Select 435.833 as the spectral line.
3. Set the slit to 25 µm. If necessary, adjust the Exposure Time to maintain optimum
(near full-scale) signal intensity.
4. Slowly move the detector in and out of focus. You should see the spectral line go
from broad to narrow and back to broad. Leave the detector set for the narrowest
achievable line. You may want to use the Focus Helper function (Process|Focus
Helper…) to determine the narrowest line width: it can automatically locate peaks
and generate a report on peak characteristics during live data acquisition (see the
WinSpec/32 on-line help for more information).
Note that the way focusing is accomplished depends on the spectrograph, as follows:
• Long focal-length spectrographs such as the Acton 300i: The
mounting adapter includes a tube that slides inside another tube to move the
detector in or out as required to achieve optimum focus.
• Short focal-length spectrographs: There is generally a focusing
mechanism on the spectrograph itself which, when adjusted, will move the
optics as required to achieve proper focus.
• No focusing adjustment: If there is no focusing adjustment, either
provided by the spectrograph or by the mounting hardware, then the only
recourse will be to adjust the spectrograph’s focusing mirror.
5. Next adjust the rotation. You can do this by rotating the detector while watching a
live display of the line. The line will go from broad to narrow and back to broad.
Leave the detector rotation set for the narrowest achievable line.
Alternatively, take an image, display the horizontal and vertical cursor bars, and
compare the vertical bar to the line shape on the screen. Rotate the detector until the
line shape on the screen is parallel with the vertical bar.
Note: When aligning other accessories, such as fibers, lenses, optical fiber adapters,
first align the spectrograph to the slit. Then align the accessory without disturbing the
detector position. The procedure is identical to that used to focus the spectrograph
(i.e., do the focus and alignment operations while watching a live image).
Summary
This completes First Light. If the system functioned as described, you can be reasonably
sure it has arrived in good working order. In addition, you should have a basic
understanding of how the system hardware is used. Other topics, which are important
under certain conditions, are discussed in the following chapters. See the appropriate
application software manual for information on using the software to control the system.