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R&D Technical Review

LIGO LabOctober 8, 2002

Core Optics

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Current Status

Coating Development» Focus on finding material or process that yield low loss coating» Need an order of magnitude reduction in loss

Sapphire Development» Focus on learning enough for the down-select decision» LASTI/Pathfinder is looming - we’re prepared

Measurement and Handling Infrastructure» Happening in the background – sort of

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Current StatusCoating Development

- Analyzed silica/tantala coatings and have a good understanding of the loss in them. » Dominated by the tantala» Same on both thin and thick substrates» Seems to be the same from both SMA/Virgo and MLD (although we

have only studied one coating from MLD).

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Current StatusCoating - Continued

Loss about an order of magnitude too high for advanced LIGO.

Unable to reproduce the low loss seen in the General Optics alumina/tantala coating (the coatings we looked at from MLD and Wave Precision were lossier than the silica/tantala)

Although still in progress, data to date suggests that silica/niobia coatings are no better than silica/tantala

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Current StatusSapphire Development

Focus on Down-Select, hot topics:» Size – Requirement is met» Absorption – Requirement is not met» Homogeneity – Can be met with compensating polish» Internal Scatter – Measure on large pieces» Birefringence – Needs work» Thermal Noise – Measure Q on large pieces

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Current StatusMeasurement, Handling & Cleaning

Measurement» Planning absorption and scatter measurement on a large scale at

CIT» Contamination testing is ongoing» Surface figure metrology is on hold

Handling» Large Optic “handler” is being made at Caltech – under

construction» Carrier development has not been started

Cleaning» Cleaning equipment/development is on hold

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Plans for 2003Coating

Coating Development» Explore silica/alumina coatings, as each material has separately

been seen to have low loss. » Explore the effects of annealing as well as other coater dependant

parameters like beam energy.» Measure Q on coatings deposited on sapphire substrates.

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Plans for 2003Sapphire

Sapphire» Measure first two full size blanks from Crystal Systems

– Absorption, Q, Homogeneity– Whatever else the down-select committee throws our way

» Resolve the a vs. m-axis homogeneity question by measuring a cube

» Continue work to lower absorption (Stanford)» Explore properties of coated sapphire» Investigate additional material supplier

– Material has been ordered, Polish and test Scatter, absorption, homogeneity

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Plans for 2003

Order/Polish/Coat LASTI RM optics Order one more LASTI TM optic (3 if FS is final TM material)

Polish LASTI TM optics Build up a scatter and absorption test capability at

Caltech Build handling equipment

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Risks & Opportunities - I

Coating Loss» Can tell exactly how bad things are and why, but no solutions yet.

– If silica/alumina is not a solution, we will have to start looking at different ideas.– The use of doped tantala is being explored at SMA/Virgo. If they have success

with it, we will pursue it as well. » The issue of coatings on sapphire is understudied.

– We assume coatings will have the same or similar loss on sapphire as on silica, little data to support this.

– May not have enough usable samples to fully explore this issue.» Modeling needed to turn coating phi's into thermal noise is not complete.

– The effect of finite mirror size isn't included. – Could significantly impact our goals. – There is interest in working on this, although progress is slow.

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Risks & Opportunities - II

The “hats” - top hat beams on Mexican hat mirrors» Used only if Sapphire is selected» Probably possible to make… still investigating tolerance

Large sapphire may not have the same properties or behaviors as we have measured in small samples» Absorption, or response to thermal treatment for absorption» Q

Fused silica still needs examination» Peter Fritchel has observed that with 100 million Q, silica is

reasonably competitive with sapphire from a thermal noise standpoint

» Possible annealing studies…

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Schedule Issues

Unlikely to have a coating chosen by 12-02, as scheduled for the LASTI noise optics.» Should make the end of 2005 when we will have to coat the optics

for the sites. Down-Select/LASTI drives the schedule

» May 03 is the current DS date » LASTI optics still deliverable

Metrology put off due to budget concerns. » Current 150 mm dia aperture is “good enough” for our current

needs.» Should be in place 1 year before “fab” substrates arrive, about the

time we place orders for blanks

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Cost Baseline and Issues

Managing the program to fit the budget Priorities

» Coating loss» Downselect

– Absorption loss

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Cost Overview3729K through 10-03

Estimate through 10-03 (SWAG16) 3,729K

Spent to date (sum of –7, -8, OPT5.4) 2,031K Unspent (remaining in –7, -8, OPT5.4)1,204K

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What we have spent

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Current cost/plan

by Oct 2003COC - Near Term Equipment expenditures Total (K) 2,362.00 903CSI-3 sap Blanks for LASTI, 100K ea 300.00 200Corning- 2 Blanks for Lasti, 50.00 50Polishing, LASTI 3sap @ 70K ea 210.00 210Polishing, LASTI 2 Rm @ 80.00 80Polish Rubicon Material 15Coating (lyon), LASTI TMs 3 @ 40K ea 120.00Coating (lyon), LASTI RMs 2 @ 40K ea 80.00 80Complete Comp polish, Goodrich 13.00 13EGO Coating Research 6 runs 24.00 24Q substrates 20 @ ~1800 36.00 36Sapphire cube (guess) 25.00 25Absorption test set (guesstimate) 200.00 100Handling Equipment 208.00 70Cleaning Equipment 363.00Metrology 653.00Modified Metrology mount 40

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Staffing Baseline and IssuesCoating – 3.28 FTE, 11 people +

“The rate limiting step in coating research is coating not measurement” -G. Harry– At MIT

Gregg Harry 1/2 FTE, Joe Betzweiser 1/4 FTE, Mike Mortonson 1/8 FTE, and Chris Vassiliou 1/8 FTE.

– At Hobart and William Smith Steve Penn is about 1/2 of his research time, or about 1/4 FTE on this project. Some

of his time will be spent at Syracuse University, but he is the only person in central NY working on coating Q.

– At Stanford Sheila Rowan is 1/3 FTE, with Marty Fejer and Roger Route about 5%.

» Norio Nakagawa is being recruited for thermal noise modeling. He does not currently have a grant to do advanced LIGO work, so things are being arranged through Stanford. I understand that he wants to work on this. May use Kip Thorne Student as a back-up

– At Glasgow Peter Sneddon is 1 FTE, David Crooks is 1/2 FTE, and Jim Hough is 10%.

– At Caltech Helena Armandula, officially 0, best guess 0.3

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Staffing Baseline and IssuesOptics – 3.55 FTE

At Caltech– GariLynn Billingsley 1.0, – Lee Cardenas 0.8– Erika D’Ambrosio 0.3– Bill Kells 0.4– Liyuan Zhang 0.75