SUPPORT

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SUPPORT OPERATIONSBUILDING/SITE
INFRASTRUCTUREREVIEW

• M1 Stripping and Cleaning
• Notes
• Gary Poczulp
• January 17, 2006

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MIRROR WASHING NOTES

• Two fundamental scenarios
• Separating M1 from cell and placing on the wash
  cart duplicating some aspects of M1 support for
  wash cart and chamber support.
• Interface with lifting fixture guide pins used
  for placement and removal of the lifting fixture.
• Mirror cover removed prior to lifting fixture
  fixture should have integral cover.
• Access will be an issue for attachment and
  detachment of axial and lateral supports.
• Possibility of not separating M1 from cell
  impacts handling scenarios, M1 cell design, and
  aluminizing chamber diameter.
• Cell already has lateral and axial supports
  eliminates need for separate supports.
• Cell will need to seal around lower edge and
  control effluent removal could be integrated
  into cell to also accommodate M1 in situ washing.
• If cell is designed to be vacuum compatible, it
  could be used as support for mirror during
  coating.

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MIRROR WASHING NOTES

• Common to both a fixture with capability to
  tilt M1 from zenith to near horizon pointing.
• Needs to be able to quickly tip mirror. Is 90
  / minute feasible?
• Mechanism
• Manual mechanical hand-crank and ratchet
  probably too slow.
• Electric motor geared.
• Hydraulic maybe too complicated
• Requires axial and lateral support.
• With separate wash fixture support have to
  consider attachment points and procedures,
  underside access.
• Both cases require mirror safeties when tilted to
  near horizon pointing.
• Watch for pinch hazards during tilting
  operations.
• Rotation of mirror not necessary.
• Seal around bottom side (or edge) to keep mirror
  back side clean and dry.

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MIRROR WASHING NOTES

• Drying
• By hand
• Relatively simple, low tech.
• Probably needs to be horizon pointing for access.
• Requires a platform that allows convenient access
  to front surface by at least six people three
  driers and three assistants.
• By air knife
• High volume air supply portable?
• Mirror tilted to at least drain angle or horizon
  pointing.
• Sub diameter air knife requires articulation to
  cover mirror without rotation possibly with
  robotic control?
• Full aperture air knife top to bottom motion -
  will need to be careful about splash up from
  around edge and bottom.

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MIRROR WASHING NOTES

• Stripping chemicals
• Drains and gutters need to be corrosion resistant
  stainless steel.
• Need to tilt to drain angle.
• Acids
• Hydrochloric acid and copper sulfate, a.k.a.
  green river.
• Cover surface with wipers to keep green river
  in place on the coated surface one application
• Nitric acid.
• One quick application.
• Bases
• Potassium hydroxide with calcium carbonate
• Scrub surface three times with KOH / CaCO3 slurry
  using long handle clean room plastic head mops.
• Filtered tap water rinse after each scrub 
• Water
• Filtered tap rinse water possibly warmed for
  cold weather washings.
• De-ionized water final rinse from bottles or DI
  water production on site.

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MIRROR WASHING NOTES

• Inspection
• Lights
• Used to monitor drying progress multiple
  sources
• Used for final inspection need to be able to
  position single high intensity source at near
  grazing incidence.
• Darkened room
• Access Issues
• To lower side of M1 and cell for attachment /
  detachment of axial and lateral supports
• Combination bridge and vertical lift to allow
  access to top side at any angle from zenith to
  horizon pointing
• For drying
• For attachment /detachment of lifting fixture
• For surface inspection / final alcohol wipe down

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MIRROR WASHING NOTES

• Magellan 6.5m M1 Aluminizing Chamber and Bridge
  2003
• Horizontal bridge allows access to zenith
  pointing mirror for washing and cleaning. Would
  need to also allow some vertical movement for
  access when the mirror is horizon pointing.
• Chamber is fixed while chamber bottom (with
  mirror and cell) is jacked upward into position
  during coating.
• Mirror is cleaned and coated while in cell.
• Manufacture DI on site

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MIRROR WASHING NOTES
Magellan 6.5m M1 Aluminizing
Chamber and Bridge 2003
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MIRROR WASHING NOTES

• Smithsonian 6.5m M1 Cleaning and Stripping 2001
• Mirror is cleaned and coated while in cell (a
  good thing) while still in telescope (not so
  good). The mirror cell is the chamber bottom and
  requires sealing plates to be installed on back
  of cell. Additionally the vacuum chamber must be
  essentially rebuilt each time it is used.
• Long handle mops are used effectively.
• Having people working on mirror surface is
  probably not a good thing.
• Additionally, the drying procedure is to have a
  crew of a half dozen workers crawl around on the
  mirror during drying and alcohol wiping. My
  understanding is that they are working on some
  sort of removable bridge arrangement for the
  upcoming coating.

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MIRROR WASHING NOTES
Smithsonian 6.5m M1 Cleaning and
Stripping 2001
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MIRROR WASHING NOTES

• KPNO 4m M1 Stripping and Mirror Cover - 2001
• Similar size to ATST M1 except it has an ample
  center hole.
• Painted wooden cover used to protect mirror.

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MIRROR WASHING NOTES
KPNO 4m M1 Stripping and Mirror
Cover - 2001
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MIRROR WASHING NOTES

• Keck 1.8m Outrigger M1 Aluminizing 2001
• Much smaller than ATST M1 but it has no central
  hole so it illustrates the problem with access to
  surface.
• Mirror is mated with axial and lateral support
  during cleaning and coating.
• Cleaning while horizon pointing and working off
  of ladders not entirely satisfying.

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MIRROR WASHING NOTES
Keck 1.8m Outrigger M1
Aluminizing - 2001
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MIRROR WASHING NOTES

Keck 1.8m Outrigger M1
Aluminizing - 2001
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MIRROR WASHING NOTES

• VLT 8m M1 Washer and Lifting Fixture 2004
•  
• Mirror cleaning machine uses chamber support for
  mirror while cleaning.
• Effective use of edge seals while stripping and
  washing.
• Clean room environment.
• Stripping and cleaning has been good, but there
  have been some problems with residue that must be
  hand wiped.
• Handling fixture has integral mirror cover.

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MIRROR WASHING NOTES

 
VLT 8m M1 Washer and Lifting
Fixture 2004