quality control of station assembly
DESCRIPTION
Quality Control of Station Assembly. Stations built so far. Prototype stations 1 – 4; had problems: Did not know which channel is the centre of the station Lots of problems on channel mapping Light loss due to hole mis-alignment at optical connectors - PowerPoint PPT PresentationTRANSCRIPT
Takashi Matsushita
Imperial College
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Quality Control of Station Assembly
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Stations built so far Prototype stations 1 – 4; had problems:
Did not know which channel is the centre of the station Lots of problems on channel mapping Light loss due to hole mis-alignment at optical connectors
Fifth station – the first production version for trackers Built with new procedure that incorporates quality control to
rectify any errors occurred during manufacturing. Improvements:
Centre fibre clearly marked during ribbon production Optical connector hole alignment checked Number of bundles in a connector checked Number of fibres in a bundle checked Sequence of fibres checked
Should have rectified problems encountered for stations 1 – 4, yet to be confirmed
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Station assembly overview First doublet-layers are manufactured at FNAL
350 m diameter fibres are laid-out on a mold with groove pitch of 426 m;1491 fibres used per doublet-layer
Then make bundles of seven fibres, put them through optical connectors, then layers stacked and glued
Quality Control before gluing them together
Centre fibre
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Bundling - i Make bundle of seven fibres starting from the centre fibre
Seven fibres held together with rubber tube => single read-out channel
“comb” is used for bundling and QC procedure; bundles are stacked in grooves of the comb, channel map defined
bundles of four columns (5-6-5-6 or 5-6-5-4) for one connector
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Bundling - ii
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Connectorisation - i A 22 way optical connector mates seven
scintillating fibres with one clear fibre waveguide;
alignment of connector holes at scintillating fibres and clear fibres sides are checked with ‘go/no-go gauge’
The scintillating fibre bundles are threaded through one of 22 holes of optical connector
Connectorisation mapping for view X
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Connectorisation - ii
“Bridge” a tool for QC
Fibre radius guide isused for connectorisation
Bridge with connectorsin place
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QC - setup Bundling/Connectorisation most labour intensive, source of errors We perform QC step after bundling/connectorisation with the setup
shown
Translation stage
LED (20 mW, = 405nm) / optics
Doublet layer
CCD
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QC– counting - i First number of bundles for a connector as well as number of fibres
in a bundle are checked after bundling and connectorisation CCD images of one connector worth of bundles are taken
Fibre bundles in comb Fibre bundles in connector
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QC – counting - ii Then software identifies bundles and fibres in the CCD image taken
Notifies operator if there are any failures
Twenty two bundles identified for comb/connector Seven fibres in a bundle identified with different colours
Analysed comb image Analysed connector image
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QC – scanning - i If counting QC was OK, move on to fibre
sequence check by LED scanning Scan fibre plane with UV LED at 1250
micron/seconds Capture image at 24.98 frames/seconds
=> 50 micron/frame [movie]
Trace sum of CCD intensity for 9 pixels around fibre centre
Bottom fibre signal distortedby the top fibres and glue
Top fibres
Bottom fibres
UV LED
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QC – scanning - ii Find frame # of intensity “peak” of each fibre;
Frame # of leading edge = maximum intensity * 0.5 Frame # of trailing edge = maximum intensity * 0.5 Frame # of ‘peak’ = (leading edge + trailing edge)*0.5
Plot frame # of intensity ‘peak’ of each fibre;
As frame # increases bundle # (channel number) increases, no overlaps of X
Fibre sequence as well as bundle order should be OK before gluing a ribbon
Max.
“peak”
Each X corresponds to ‘peak’Seven X in each bundle
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QC – scanning - iii
Samples of errors identified during assembly
Fibre swap between bundles17&18 and 19&20
Wrong bundle order
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QC – scanning - iv Time interval of each ‘peak’ checked as well Negative interval if there is fibre swap between bundles
mean = 4.24 frames => 212.17 micronagrees with measured mold pitch of 426/2 micron
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Point of no return - gluing Fix vacuum chuck, carbon-fibre station frame to gluing jig
Then glue them together
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Potting & polishing Pot fibres to connectors, then apply glue to stiffen fibres then cut
and polish
Apply glue Cut fibres
After polishing
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Summary
New station assembly procedure with QC process incorporated worked out to overcome problems seen in prototype stations
Station 5 built with new manufacturing procedure, which proven to work
4473 350 micron fibres successfully bundled and connectorised by hand
Ready for test with read-out
Station assembly is underway with the new assembly procedure