The HeNe Laser Head (613A10300, #12 on figure) produces the
laser beam.
The beam passes through a bellows (#38) that reduces dust and
prevents air disturbances. The beam continues through an ND filter (#23). The filter
reduces the laser intensity to make it suitable for the exposure.
The laser beam is focused by a lens (#21) onto the fiber
optics cable. The lens positions the beam on the center of the fiber such that the beam is
at maximum intensity at the exit from the cable.
The fiber cable leads the beam to the RF modulator assembly.
The RF modulates the laser beam consistent with the data. It can be adjusted for Bragg and
tilt. The assembly is designed such that the first order beam is at maximum intensity at
the exit point from the RF Modulator Assembly. The connection to #2 is directly after the
beam passes though the bellows (#3). The entire subunit is adjusted separately in the
factory and assembled on the static optics.
A lens is connected to the fiber at the point where it enters
the modulator. The lens is inside the laser fiber assembly (#17). The lens focuses the
beam on the RF modulator. The purpose is to achieve a high enough rise time. See #17 on
the drawing. The beam passes through the RF Modulator and enters another bellows (#3) and
lens. The second bellows also reduces dust and prevents air disturbances. The lens (inside
the modulator fiber assembly) positions the beam once again on the center of the
modulator.
From this point the laser beam passes through an optical
connector, an optical connector adaptor, and another optical connector. The connectors are
at the point between the light area and dark area of the Imagesetter.
The optic fiber passes through the tilting plate. The tilting
plate allows for tilt adjustment of the fiber cable, and adjustment on the x/y axis, to
enable adjustment of the beam parallel to the drum axis.
Activate the laser beam using the Laser/Mod RPC function in
diagnostics. (Turn the laser on , turn the modulator on (10,000), and turn the shutter
off. Write down the value you received from the LD. This value will be the reference.
If the laser is dead, locate this value from the tables.
Prepare a clean surface to place the static optic fiber and
the optical cleaning kit (optional)
Power off the imagesetter using the control panel ON/OFF
switch.
Position the new static optic assembly on the main frame.
Fasten the three screws that secure the assembly to the
mainframe.
Connect the RF cable to the A/O modulator.
Reconnect the laser exciter power main cable connector.
Switch on the circuit breaker on the back of the imagesetter.
Power on the imagesetter through the control panel on/off
switch.
Start the Dolev 800 Diagnostics program.
Activate the laser beam using the Laser/Mod RPC function in
diagnostics. (Turn the laser on , turn the modulator on (10,000), and turn the shutter
off. Write down the value you received from the LD. This value will be the reference.)
Remove the red cap from the fiber connector. Fold a piece of
rice paper, taking care not to touch the cleaning area. Soak the folded paper with alcohol
(be careful, acetone is forbidden).
Clean the fiber connector with the pad. Wait a few seconds for
the alcohol to evaporate.
Connect a power meter to check that the power from the static
side is at least 200 milliWatts. If not, change the static optic assembly.
If the power value is at least 200 milliWatts, remove the
black cap from the adaptor and connect the fiber connector to the adaptor.
Check that the value in the LD is close to the one you had
when you began to change the static optic assembly.
If the laser was dead before, check that the intensity of the
beam on the surface of the drum is at least 100 milliwatt. (Measure it with a power
meter.)
The optical fiber transfers the laser beam from the laser to
the dynamic optics, and from there to the film surface.
The fiber is sectioned into two parts. One part belongs to the static optic and the other
is connected to the dynamic optic. Each end is fixed with a ceramic connector. The optical
connector adaptor unit mates the two connectors.
The optical fiber connection is located on the left side of the imagesetter. To reach the
assembly, open the left service door. Remove the protective cover from the lower
compartment of the Dolev 800.
Turn the connector a half turn and pull it out, or unscrew the
connector (depending on the type of connector).
Clean the connector. Use the adaptor brush to clean the adaptor (supplied in the fiber
optic cleaning kit). Make sure that no dirt, dust or lint is left by an air stream from
compressed air can.
Cover the connector with a black cap supplied in the fiber
optic cleaning kit.
Cover the open side of the adaptor with the cover supplied in
the fiber optic cleaning kit.
Use the same method for the other side of the fiber.
Note: The laser exciter for Dolev 800 is factory-set
for 220V operation.and comes with a suitable 220 V connector . This differs from the Dolev
200/400.
Important!! If you're using a Dolev 200/400 laser exciter, make sure to change the
connector and the wiring.
The laser-exciter wiring (cat. no. 504B29756) is located in the Static Optic Assembly
(cat. no. 509E29496). The static optic assembly is located on the bottom left side of the
imagesetter.
To reach the assembly, open the left service door. The laser-exciter wiring is located in
the lower compartment of the static optic assembly and is held in place by two locking
screws.
The purpose of the assembly is to supply power to the laser. Over time, it might happen
that the laser exciter will break down.
Static
Optic