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Scanning the PLATE
1234563 – 12/12/94
Status: Preparation for Scanning
• SLOW SCAN MOTOR is stopped.
• PLATE is at the NOSEPIECE Engaged position.
• NOSEPIECE is engaged
• LASER SHUTTER is open.
• LASER POWER is on and verified.
• PMTs are on high current.
• Signal Channel is zeroed.
[1] The MCPU:
(a) Turns the GALVO on.
(b) Tells the MSC to start the scan, which in turn starts the SLOW SCAN
MOTOR
(c) Tells the INTERNAL PC that the scan is beginning.
[2] The INTERNAL PC displays a Timed Progress Bar, which is available on
the TOUCH SCREEN MONITOR. This is a graphical display only and not a
real time indication of the progress of the scanning operation.
[3] The SLOW SCAN MOTOR turns, moving the PLATE through the field of
scan in the slow scan direction, a true vertical movement.
[4] The GALVO BD directs the sweep of the LASER beam across the PLATE
in the fast scan direction. The PLATE is scanned one pixel at a time, one
line at a time.
The fast scan movement consists of a nearly horizontal trace across the
PLATE, from the back of the unit toward the front. When it reaches the end
of a line, it does a quick retrace to start another line. Throughout the PLATE
is moving down at a controlled velocity so that each fast scan trace is 1 pixel
value higher up on the PLATE than the previous line. The result is that the
fast scan is in a slightly diagonal trace across the PLATE
SEQUENCE OF OPERATIONS
11–55
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