Transcript OptoMechanic_Impact.ppt

WMKO Next Generation Adaptive Optics:
AO System Design Impact of Cost
Savings Ideas
Don Gavel
December 19, 2008
AO Design Impact - Highlights
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We revisited the AO architecture to look for cost savings
– Considered several options of 1 and 2 stage relays
– All the 1 stage options were more expensive
– 140 mm 1st stage appears to be the lowest cost and risk
– Summary in KAON 628
Possible savings by eliminating “switchyard”
– ROM quotes on dichroics in progress now
– Effect on emmissivity at K-long (key issue) is not resolved – need
input on IFU pickoff and MEMS relay design
– Floating idea of no MEMS in the IFU path. Severe impact on
encircled energy requirement expected. [KAON 471, Don’s
presentation at SD Team Meeting 4. ]
– Floating idea of no pickoff for IFU – saves on cost of pickoff and
has less emissivity due to fewer surfaces
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AO Design Impact - item by item (page 1)
• Single NIR IFU
– Pickoff?
• No PSF monitor DM no TT mechanism on TWFS
– Would require higher quality FSM in 1st relay than envisioned
• Reduced laser power
– No impact
• Fix central four LGS beacons
– Eliminates pickoff mechanisms
• Lasers on elevation ring
– No impact
• Single level cascaded relay
– Saves cost of engineering the 2nd level structure
– Re-use DM? I sent a message about this – it may be possible to work
around the hystersis issues due to our woofer-tweeter architecture
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AO Design Impacts - item by item (page 2)
• Don’t use OSIRIS
– Saves engineering cost of feeding OSIRIS
• No visible imager
– Considerably simplifies the switchyard. The IR/Vis switchyard is a very
crowded area in the cascaded relay layout and has several mechanisms
for switching observing modes.
• 2 instead of 3 LGS WFS lenslet arrays
– No impact
• No ADC on NGS WFS
• Reduced switchyard opto-mechanics – see above on OSIRIS and
vis imager
• Reduce proj mgmt and sys eng
– Increases risk
• Fewer controlled devices
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AO Design Impacts - item by item (Last page)
• Reduced RTC complexity
– Some savings here – most likely only hardware costs
– Still need to evaluate
• Higher MEMS costs
– Not a good trend, but customers are paying
– Should try to negotiate a “package deal” given we would be buying
multiple MEMS
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