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The Carbon Fiber |
| The carbon fiber sometimes referred to as a Quartz fiber is the heart of the
pocket dosimeter operation. When you look through the eyepiece toward a
light source (fluorescent light, window, not the sun) you see the carbon fiber's
shadow cast on the graduated scale. |
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| Each strand you see here contains several
hundred individual fibers. Each
fiber is approx. 1/10 the diameter of a human hair. |
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The Frame |
| The fiber is held in place in the pocket dosimeter by an
aluminum frame The lenses that are in the dosimeter act as a microscope
to read the shadow of the fiber on a graduated scale etched on the reticle. |
| The aluminum frame is what holds the conductive fiber
(carbon, quartz) in the dosimeter. The yellow line represents the approximate location of the carbon
fiber, the fiber is too small to be seen with the naked eye. |
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The legs of the frame is inserted (by injection molding)
into an electrometer which is an extremely good insulator (FEMA
preferred formula) |
| Aluminum sheeting that the "frame" is stamped out of |
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| The stamping machine stamps out the "frame" you can see the holes
left in the aluminum sheeting |
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The
Process of placing the fiber on the frame |
| One of the most delicate operation's of manufacturing the dosimeter is the
placing of the fiber onto the aluminum frame. This has to be done with
great care and precision as to protect the fiber from being destroyed. |
| The next few photos show some of the
workers and equipment involved in the placement of
the fiber onto the frame. (Meet
the production staff) |
| Vickie is finding one individual fiber from a bundle. The desk she is
working has a florescent light in it to aid in finding the extremely small
fiber. |
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| After finding a fiber she places it onto the frame by looking through the microscope
to tell when it
is in the correct position for the machine to attach it. |
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| After the fiber is attached to the frame, It is bent into the horse-shoe shape
ready for the next step. |
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Arrow-Tech, workers (Pat, Dianne, Gloria, Sandy, Vickie, Bennett) taking the completed frame with
attached fiber and getting it prepared to have the legs of the frame placed into
the electrometer (using the FEMA preferred formula). This is done by a process called injection molding. |
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| In this photo you can see the FEMA preferred formula material leading up to the
mold where the frame is waiting to be placed into the material. |
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| Sandy is clipping the excess molding from the
newly formed electrometer with the frame
inserted. |
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Vicky checking with the microscope if the fiber is still connected to the frame
after the frame is attached to the electrometer. |
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| Sandy
placing protective cover over the newly made piece of the frame attached to the
electrometer. This insures the carbon fiber remains intact to the next step. |
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| Diane takes the completed frame/electrometer and places
it into an ionization chamber. She also adjusts the zero voltage and
matches the correct size chamber (1,2or3) for calibration purposes. |
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| Gail and Pat winding capacitors. A capacitor is
needed in the high range (2R,5R,20R,100R,200R,600R) models. A capacitor
is required for proper calibration and accuracy. |
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| Sandy, Cassie & Darwin fitting the newly wound
capacitor with an insulating jacket. Click
here to see a short movie of the process, (need QuickTime
installed) |
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| Bennet inspecting a cover that he is molding. The
cover is for the capacitor that is needed in the 5R dosimeter. |
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| Terry inspecting a mold that is needed for the one of the injection
molding process. |
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Molding the Lens |
| Before the plastic can be used
for whatever purpose (lens, eyepiece, etc) it must be dried to remove
all traces of moisture. This picture shows a 28 ton injection molding
machine with a dryer attached. (red hoses and hopper) |
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| Bennet trimming the excess plastic from the Lenses |
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| After the lenses are made, they are placed in dryers to
finish removing any possible moisture. |
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Gail is focusing the objective lens. The lens is
glued into a smaller barrel called the objective lens holder that has
threads on the outside. The objective lens holder is screwed
into the dosimeter barrel until the fiber is in proper focus on the
scale. |
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Hermetic Sealing process |
| Irene applying the Hermetic Sealing epoxy that binds the protective window to the barrel.
This is very strong material made out of special epoxy. |
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Gloria gluing the eye cup to the inside of the barrel |
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Gail and Ron assembling the upper and lower barrels of the
dosimeter. Gail checks to see if the fiber is in proper alignment
with the scale before final assembly. Ron places the two barrels
together and presses the two together. There is glue that is
applied also to make a permanent connection and to provide a hermetic
seal.
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| After the Dosimeter is put together, the
Calibrating & Testing process begins (step 3
of tour) |
