CAL & ADJUST
3-7
Versapulse Select Service Manual
0621-499-01 03/94
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It may often be appropriate to do less than the complete adjustment, but in such a case the field service engineer
must consider the possible effect of doing only a portion, i.e., the adjustment may have an effect on some other
portion of the alignment. As an example, If a single channel is only slightly out of center at the fiber port, it can
usually be corrected by simply adjusting the first relay mirror (using the fiber detector signal) and then confirming
the adjustment using a test fiber burn and second wedge optic burn.
When replacing a damaged optic, it should not be necessary to do the entire procedure - try to bring the system
back into alignment by just adjusting the optic that was replaced.
3.4.1 Making Test Burns
(Refer to figures 3.2 and 3.3) Checking out and aligning the YAG channels requires making burns on photopaper
to check alignment. The Alignment Aperture and Cross Hair Aperture are two special purpose tools used when
making burns.
In general, when making burns, lower pulse energies and fewer total pulses are better. As the total energy into
a burn increases, the footprint becomes "blurred". In some cases it will be necessary to get a "multiplexed
footprint", i.e., the paper is burned by more than one channel, allowing the YAG beam positions to be compared.
In other cases a single channel burn will be required. The service engineer can select the channels to be fired, a
cap charge voltage and a pulse rate at the service screens. Setting a lower pulse rates allows the footswitch to be
operated to obtain just a single pulse from a channel, or from each selected channel.
The alignment aperture is used to center the YAG beam(s) in front of the second wedge optic. It holds a piece of
burn paper (covered on both sides with plastic to contain splatter). A good burn will fall inside the aperture (the
aperture will not clip the beam). The tool is keyed with two small posts that fit into holes on the face of the second
wedge optic housing block. To use the aperture, slide burn paper and plastic in through the side, then insert it
on the second wedge optic housing.
The cross hair aperture is used to align an individual cavity (OC and HR) into the center of the first relay mirror.
To install it, the first relay mirror mount is removed, then the aperture slides into a hole in the wall directly behind
the spot the channel first relay mirror was mounted (insert from the outside of the wall, so that it is further from
the channel OC). The aperture has two small wires running across it that block a small portion of the beam
(perpendicular to each other and crossing in the center of the aperture). The resulting burn will have the cross
hairs superimposed on it. The cavity optics are adjusted to center the burn in the cross hairs.
3.4.2 Adjusting the YAG Channel Optics
(Refer to figure 3.4) The channel HR, OC and relay mirrors all have the same basic adjustment mechanics. The
mirror is held in a mirror mount by a metal retainer. The mount attaches to one of the optics bench walls by a single
mounting screw with spring. The spring pulls the mount towards the wall - two adjusting screws and a ball
bearing hold the mount out away from its mounting surface against the tension of the spring. One adjusting
screws provides horizontal movement and the other provides vertical movement.
A locking nut is threaded onto each adjusting screw. To unlock the screw for adjustment back the locking screw
away from the collar. Once adjustment is complete, lock down the adjustment screw by turning the nut down
against the collar. As is common in such mechanical lock down set ups, the locking down process will change
the adjustment a bit, so use the locking down to bring the optic to its optimum position. It is best to use the hex
wrench to hold the adjusting screw in place while tightening down the locking nut with the box end wrench. The
adjusting screws require a 7/64th hex head wrench. The locking nuts require a 7/16th box end wrench.
12/95
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