CAL & ADJUST
3-10
VersaPulse Select Service Manual
0621-499-01 03/94
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An unacceptable burn will be well off center (more than a fourth of the burn is
clipped) In this case, the second relay mirror must be adjusted to bring the YAG
beam closer to the center of the aperture as described below.
Make a slight adjustment to the second relay mirror, then check the result by
making a burn on photopaper at the second wedge optic. Because a number
of burns may be required to complete the adjustment, using the test aperture
can slow things down (the aperture would have to be reloaded with a clean
piece of paper after each shot). As an alternative, find a second channel that
is already centered in the aperture, and then use the service screen to turn
that channel on as well as the channel to be adjusted. When the laser is fired
the two channels will each fire in turn. Instead of using the aperture, make
the burns on a larger piece of paper held in front of the aperture, moving to a
clean spot for each check. The known good channel becomes the reference -
adjust the second relay mirror for the channel out of adjustment until the
burn footprints are on top of each other. Once the channel is roughly
positioned over the aperture, lock down the mirror and go on to step "b"
below.
b.) Align the YAG beam into the fiber port using the Fiber Alignment Detector Box.
Insert the service attenuator into the beam path (switch is on the Shutter PCB). Connect the
fiber alignment detector box to the fiber port and oscilloscope. Select a 40 Hz pulse rate
(really 10 Hz since only one channel is on), then adjust as indicated in the subparagraph
below.
Fire the laser while observing the oscilloscope. Each laser pulse will produce a
square pulse on the screen (≈ 2 mseconds pulse width). Make slight adjustments to
the channel first relay mirror to peak the amplitude of the pulses on the oscilloscope.
c.) Check the burn into the second wedge optic using the test aperture.
The beam must be unclipped. If not, repeat steps "a" and "b" above until both pass with the
adjustments mechanisms locked down.
6. Do a burn footprint into the test aperture with all four channels turned on.
The resulting burn footprint should be circular in shape and contained in the aperture (no clipping).
7. Perform the system checkout as outlined in Topic 3.2
3.5 AIMING BEAM ADJUSTMENT
The aiming beam can be adjusted by repositioning the aiming diode mount or by adjusting the position of the
folding mirror (the mirror that directs the aiming beam onto the beam combiner). In either case, observe the
aiming beam output from the fiber and adjust to obtain a full spot of bright red light (no doughnut).
12/95
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