Coherent Model 541 Carbon Dioxide Laser, 5 to 50 W (Gallery)
While the Coherent 541 has a fancy looking control panel with loads of bells
and whistles - and no doubt had an equally fancy price tag when it was new,
the basic design is very similar to the CO2 laser described in an Amateur
Scientist column of Scientific American in the mid-70s (and found in the book,
"Light and its Uses") as well as others providing CO2 laser project plans.
The power supply is basically just a neon sign transformer on a Variac. Gas
handling is via an H-bottle of CO2 gas mix, regulator, valves, and single
stage rotary vacuum pump. Cooling is a via closed loop coolant-to-air heat
exchanger.
(The following 16 photos and descriptions provided courtesy of: Curt Graber
(cgraber@fwi.com).)
These photos are of a Coherent Model 541 medical/surgical CO2 laser system
which was removed from service because it was overtemping based on a
restriction in the coolant flow from the tube to the closed loop chiller
onboard (the restriction was a debris blockage in the coolant temp sensor
which was in less than 10 min remedied).
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View 01 - Coherent Model 541 medical/surgical CO2 laser system, all covers
removed to allow a complete visual and confirmation of all the vitals and
fluid levels prior to power up. Left side is the on-board vacuum pump system
to pull the tube into range of pressure needed to allow lasing. The actual
head is hanging on the left side with articulated arm already mounted.
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View 02 - Front view of the unit with control panel for adjustments for
the laser system, coolant pump visible in the lower front cavity.
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View 03 - Control panel going through it's power up test. Note the big
blue power knob on the right and the autopulse features and controls center of
the panel. Power in watts CW is displayed in the right side large LED display.
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View 04 - Vertically arranged CO2 plasma tube, and HeNe pointer tube and
power supply.
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View 05 - Back view. CO2 mix bottle and primary regulator on the right,
center is the 1 gal closed loop coolant bottle with more debris floating in it
than I'd normally like to see in a precision laser device.
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View 06 - Front view of lower cavity showing vacuum pump motor (right
side), chiller fans and box (left side), and coolant pump (lower left side).
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View 07 - Top view with the service tools equipment tray removed to allow
a view of the power supply (the shock, a common site of a blue Jefferson 15 KV,
60 mA neon sign transformer), and a Variac (autotransformer) for the primary
voltage adjustment. Controller boards and chiller box are in the lower left
hand corner.
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View 08 - Plasma tube and HeNe alignment laser are lit and ready for action
resonator length is approximately 28" and the HeNe tube shows serious signs
of helium depletion or some other problem as the unit would cycle it's output
continuously.
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View 09 - Pretty pinkish/purple tube plasma along the length of the bore.
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View 10 - Doing a little freehand wood burning. The focus is approximately
1" from the end of the tip. Note the assist gas port at the top of the picture
not currently being used.
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View 11 - How about a glass wine bottle - the laser cuts/breaks and or
inscribes based upon power settings - neat effect when the laser hits the
glass a tearing/poping sound is produced and the glass is lit up from the
arc as if a lamp is being fired along the axis of the glass.
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View 12 - Another view of the glass/arc.
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View 13 - Close view of the burn just as the glass cracks form the heat
input.
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View 14 - An even closer view.
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View 15 - Attachments, tools, and articulated arm are kept snug as a bug
in the foam lined center tray for easy storage and access.
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View 16 - Laser warning tag 60 W max for the CO2 beam and the .8 mW HeNe
pointer laser.
