SOL-GEL COATING FACILITY

CONCEPTUAL DESIGN REVIEW

October 19, 2005

Purpose• Develop the ability to dip coat large optics with sol-

gel solution in conjunction with our vacuum coating facility.

• Design parameters.– Maximum size optic: 44” diameter, 4” thick, 4,600

cu. in. volume (44” dia X 3” thick)– Ability to vacuum coat than sol-gel coat in a clean

environment– Initial sol solution TEOS, provide for an additional

solution type– Locate facility in upper astronomy shop optics lab.

• Initial Goal– Coat ADC prisms with MgF2 and Sol-gel– ADC prisms are 41” dia. wedges approx 7/8” X 2

7//8” thick

DESIGN

• Dip coat facility in clean room environment

• Optic handling equipment for ADC optics.

• Handling equipment optic specific in general

• Interface with vacuum tank facility

CLEAN ROOM

• Erect clean room in optics lab to include vacuum & Sol-gel coating– Initial quote for a 25’ X 25’ X 8’class 1000 room

including HEPA filters & fans $16,000

ADC OPTIC HANDLING

ADC OPTIC HANDLING

• Use a frame with Teflon pads instead of band strap• A U-shaped frame with interchangeable upper cross

members– One for general lifting & turning optic over– One for Sol-gel dip– One for hardening (not shown)

• Optic restraint for general lifting & turning over is provided by 4 U shaped Teflon pads

• Optic constraint for Sol-gel dip is provided by 3 U shaped Teflon pads

• Might be able to support optic by bevels with flat part of U being for safety

Transport between stations on cart with 4 swivel wheels

•Uprights (Item 3) slide into frame channels, bottom frame channel sets on beam•This supports optic vertically to move around and to change top bars•Bottom of cart is generic for most large optics•Uprights are specific to ADC optic•Remove frame for vacuum coating Load into vacuum chamber with stand used for previous coating

Revise mounting in vacuum tank to work without band used last time

•Sol-gel fixture is equipped with a ½ ton crane and trolley on a beam Garment supplier can provide fabric covers for hoists

•To load optic into Sol-gel fixture Push optic into enclosure on cart Lift optic with ½ ton crane Roll trolley back to lift fixture Lower optic onto lift fixture

SOL-GEL FIXTURE

SOL-GEL FIXTURE

• Two dip tanks and a cleaning station– Dip tanks 54” X 8” X 50” high, inside– Sides supported by steel frame (not shown)– Lid opens in 2 halves with shield at ends to provide

extension of vapor height to 6”– Pneumatic opener on lid to operate remotely– Stainless steel or polypropylene (poly quote $940)

• Cleaning station design TBD– Include CO2 snow and N2 blow off, operated

remotely

•Compensator to hold Sol-gel level constant in dip tank Provides constant vapor height in dip tank Prevents plating of tank sides Connection to tank 1” dia. Teflon tube Overflow to be provided on sol-gel tank in case of compensator malfunction (volume = to compensator volume)

•Tanks & compensator mounted on a carriage Moves from position shown to Sol-gel dip position Steel rollers Manual drive with stops for positive location

•Lift mechanism to raise & lower optic at programmed rates Single ball screw & 2 ball slides almost identical to ADC mechanism Ball Screw 40 mm dia. by 5 mm pitch NSK Bayside 10:1 gearbox Pitman motor driven by Galil controller Encoder on motor NSK quote for ball screw and ball slides $5,000 (not including end bearing mounts for ball screw)

•Hoist & hoist beam to load optic onto lift mechanism•Structure mounted on vibration isolators TBD

Probably Barry mounts (same as profilometer) Base vibration requirement on size of meniscus photographed while pulling microscope slide in NC mill

COMPENSATOR

COMPENSATOR

• Shown as stainless steel, quote on 20’ X 12” X ¾” wall dia. polypropylene tube $600– Volume to be 21 gal. Min.– Height not above top of fluid level in tank

• NSK ball slide and ball screw quote $4,600 (not including end bearings)

• Ball screw 32 mm dia X 5 mm pitch• Ball nut held stationary at top of cylinder• Ball screw and motor / gearbox move up & down guided

by ball slide• Additional rod to prevent piston rotation• Bayside gearbox and Pitman motor controlled by Galil

controller• Bleed in piston not shown• Piston relieved at end to allow it to go to bottom of tank

without restricting output

STRUCTURE

• Steel weldment– Start with Deimos rails– Epoxy paint

ENCLOSURE

• 2” X 2” X 1/8” wall steel tube welded frame

• Clad with 1/8” thick plexiglass

• ¼”thick plexiglass doors on front, open from center

• HEPA filters & fans on side near top

HARDENING / HMDS TANK

• Use existing tank

• Improve insulation

• Load optic from cart under overhead crane

SOFTWARE

• Control for 2 stage axis

• One on lift mechanism requires lift and constant rate

• One on compensator has varying rate depending on optic geometry