Atmospheric Dispersion Compensation: manufacturing issues

1
Atmospheric Dispersion Compensation
manufacturing issues
Scot Olivier Sept. 9, 2004
2
Fabrication of ADC prism pair
2
Bond prism pair
1
1
Make prism from thick piece of glass
Make prism from thick piece of glass
3
Thin bonded prism pair, adjust prism angle
Diameter 1 meter Prism angle 0.75
degrees Final thickness 30 mm (thinnest prism
edge 2 mm)

• Require two prism pairs that have closely matched
  prism angles
• high quality surfaces and high control of
  wedge angle

3
Glasses for ADC must closely match indices of
refraction while maximizing dispersion difference
4
ADC Manufacturing Issues

• ADC glass procurement
• Vendor discussions ongoing
• Custom melts would have cost and schedule impact
• Bonding ADC plates
• Vendor experience is promising
• Technical risks could affect cost, schedule
• Polishing
• Vendor capabilities sufficient
• Testing
• Standard tests for large flats
• Coating
• AR coating for bonded prisms is challenging
• Impact on performance (throughput, ghosts), cost
• Costs
• ADC (glass, fabrication) guess 1-2M
• Increased size of L1 guess 300-500K
• Schedule
• Nominally 1 year glass procurement, 1 year fab
• RD aspects require extra time in schedule