LIGO Status and Plans

1
LIGO Status and Plans

• Barry Barish
• AIP Conference, Sydney Australia
• 11-July-02

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2007
3
A tour of LIGO
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LIGO Sites
Hanford Observatory
Livingston Observatory
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LIGO Livingston Observatory
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LIGO Hanford Observatory
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Detection Strategycoincidences

• Two Sites - Three Interferometers
• Single Interferometer non-gaussian level 50/hr
• Hanford (Doubles) correlated rate
  (x1000) 1/day
• Hanford Livingston uncorrelated
  (x5000) lt0.1/yr
• Data Recording (time series)
• gravitational wave signal (0.2 MB/sec)
• total data (16 MB/s)
• on-line filters, diagnostics, data compression
• off line data analysis, archive etc
• Signal Extraction
• signal from noise (vetoes, noise analysis)
• templates, wavelets, etc

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The Beam TubeEnclosure
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LIGO Facilitiesbeam tube enclosure

• minimal enclosure
• reinforced concrete
• no services

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LIGObeam tube

• LIGO beam tube under construction in January 1998
• 65 ft spiral welded sections
• girth welded in portable clean room in the field

1.2 m diameter - 3mm stainless 50 km of weld
NO LEAKS !!
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LIGO I the noise floor

• Interferometry is limited by three fundamental
  noise sources
• seismic noise at the lowest frequencies
• thermal noise at intermediate frequencies
• shot noise at high frequencies
• Many other noise sources lurk underneath and must
  be controlled as the instrument is improved

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Beam Tube bakeout

• I 2000 amps for 1 month
• no leaks !!
• final vacuum at level where it is not source of
  limiting noise (even future detectors)

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Vacuum Chambers
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LIGOvacuum chambers
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Vacuum Chambersvibration isolation systems

• Reduce in-band seismic motion by 4 - 6 orders of
  magnitude
• Compensate for microseism at 0.15 Hz by a factor
  of ten
• Compensate (partially) for Earth tides

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Seismic Isolation
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Seismic Isolation springs and masses
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Seismic Isolationconstrained layer damped springs
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Seismic Isolation
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OpticsSuspensions
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Core Opticsfused silica

• LIGO requirements
• Surface uniformity lt 1 nm rms
• Scatter lt 50 ppm
• Absorption lt 2 ppm
• ROC matched lt 3
• Internal mode Qs gt 2 x 106

• LIGO measurements
• central 80 mm of 4ITM06 (Hanford 4K)
• rms  0.16 nm
• optic far exceeds specification.

Surface figure ?/ 6000
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Seismic Isolationsuspension system
suspension assembly for a core optic

• support structure is welded tubular stainless
  steel
• suspension wire is 0.31 mm diameter steel music
  wire
• fundamental violin mode frequency of 340 Hz

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Core Optics installation and alignment
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LaserMode Cleaner
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LIGO laser

• NdYAG
• 1.064 mm
• Output power gt 8W in TEM00 mode

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Laserstabilization

• Deliver pre-stabilized laser light to the 15-m
  mode cleaner
• Frequency fluctuations
• In-band power fluctuations
• Power fluctuations at 25 MHz

• Provide actuator inputs for further stabilization
• Wideband
• Tidal

10-1 Hz/Hz1/2
10-4 Hz/ Hz1/2
10-7 Hz/ Hz1/2
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Prestabilized Laser frequency noise

• Simplification of beam path external to vacuum
  system eliminates peaks due to vibrations
• Broadband noise better than spec in 40-200 Hz
  region

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Pre-stabilized Laser laboratory data vs e2e
simulation
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Locking the Interferometers
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Interferometerlocking
end test mass
Requires test masses to be held in position to
10-10-10-13 meter Locking the interferometer
Light bounces back and forth along arms about 150
times
Light is recycled about 50 times
input test mass
Laser
signal
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Lock Acquisition
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LIGO watching the interferometer lock
Y Arm
Laser
X Arm
signal
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LIGO watching the interferometer lock
X arm
Y arm
Y Arm
Anti-symmetricport
Reflected light
Laser
X Arm
signal
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E7 Engineering Run

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LIGO Interferometers E7 sensitivities
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E7 Run SummaryLIGO GEO Interferometers
28 Dec 2001 - 14 Jan 2002 (402 hr)
Coincidence Data All
segments Segments gt15min 2X H2, L1 locked
160hrs (39) 99hrs
(24) clean 113hrs (26)
70hrs (16) H2,L1 longest clean segment 150 3X
L1H1 H2 locked 140hrs (35)
72hrs (18) clean 93hrs (21)
46hrs (11) L1H1 H2 longest clean
segment 118 4X L1H1 H2 GEO 77 hrs
(23 ) 26.1 hrs (7.81 ) 5X ALLEGRO

• Singles data
• All segments Segments gt15min
• L1 locked 284hrs (71) 249hrs
  (62)
• L1 clean 265hrs (61) 231hrs
  (53)
• L1 longest clean segment 358
• H1 locked 294hrs (72) 231hrs
  (57)
• H1 clean 267hrs (62) 206hrs
  (48)
• H1 longest clean segment 404
• H2 locked 214hrs (53) 157hrs
  (39)
• H2 clean 162hrs (38) 125hrs
  (28)
• H2 longest clean segment 724

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Engineering Run detecting earthquakes
From electronic logbook 2-Jan-02
An earthquake occurred, starting at UTC 1738.
The plot shows the band limited rms output in
counts over the 0.1- 0.3Hz band for four
seismometer channels. We turned off lock
acquisition and are waiting for the ground
motion to calm down.
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170303 01/02/2002


Seismo-Watch Earthquake
Alert Bulletin No. 02-64441


Preliminary data indicates a significant
earthquake has occurred
Regional Location VANUATU ISLANDS
Magnitude 7.3M
Greenwich Mean Date 2002/01/02
Greenwich Mean Time 172250
Latitude 17.78S
Longitude 167.83E Focal
depth 33.0km Analysis
Quality A
Source National Earthquake Information Center
(USGS-NEIC) Seismo-Watch,
Your Source for Earthquake News and Information.
Visit http//www.seismo-watc
h.com

All data are preliminary
and subject to change.
Analysis Quality A (good), B (fair), C (poor), D
(bad) Magnitude Ml (local
or Richter magnitude), Lg (mblg), Md (duration),


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Detecting the Earth Tides Sun and Moon
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Run Plancommissioning data taking

• Science 1 run 13 TB data Upper Limits
• 29 June - 15 July (delayed until gtAug 1 because
  of broken suspension wire)
• 2.5 weeks - comparable to E7
• Target sensitivity 200x design
• Science 2 run 44 TB data Upper Limits
• 22 November - 6 January 2003
• 8 weeks -- 15 of 1 yr
• Target sensitivity 20x design
• Science 3 run 142 TB data Search Run
• 1 July 2003 -- 1January 2004
• 26 weeks -- 50 of 1 yr
• Target sensitivity 5x design

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Commissioning Status for S1 Science Run
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LHO 2 km InterferometerStatus

• Locked in power recycled configuration
• recycling factor up to 25, but typically 15
• Common mode servo implemented
• Frequency stabilization from average arm length
• Establishes control system gain hierarchy
• 5 W power into mode cleaner
• Attenuators at photodiodes give effective input
  power 20 - 40 mW
• Tidal feedback operational
• Lock duration up to 15 hours
• DISPLACEMENT Sensitivity

Summer 2001 3 x 10-16 m/Hz1/2
December 2001 (E7) 5 x 10-17 m /Hz1/2 (600 Hz)
Spring 2002 2 x 10-17 m /Hz1/2 (350 Hz)
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Interferometer sensitivity history
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LHO 4 km Interferometerstatus

• In-vacuum installation completed last summer
• Digital suspension controllers
• Greater flexibility for tuning servos to improve
  reliability/noise
• Permits frequency dependent orthogonalization of
  the displacement and angular control of the
  suspensions
• Will be implemented on other interferometers
  after tests done
• 1 W power into mode cleaner
• Attenuators at photodiodes give effective input
  power 20 mW
• Locked in power recycled configuration
• Recycling factor typically 40-50
• Tidal feedback operational
• Locks up to 4 hours
• DISPLACEMENT Sensitivity 2 x 10-16 m/Hz1/2

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Interferometer sensitivity history
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LLO 4 km Interferometer status

• Power recycled configuration
• 1.9 W power input laser power into mode cleaner
• Power recycling gain 50
• 25-30 dB attenuation at dark port
• Reasonably robust lock during night
• Up to 4 hours
• 15 s 3 min lock acquisition time
• Tidal feedback operational
• Wavefront alignment control operating on end
  mirrors
• Microseismic feedforward reduces the dynamic
  range required from the controller (unique to LLO
  at present time)
• PEPI reduces the seismic noise injected between
  0.3 to 5 Hz at the end masses
• DISPLACEMENT Sensitivity 1.5 x 10-17 m/Hz1/2 _at_
  400 - 600 Hz

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Interferometer sensitivity history
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Astrophysical Sourcessignatures and data analysis

• Compact binary inspiral chirps
• NS-NS waveforms are well described
• BH-BH need better waveforms
• search technique matched templates
• Supernovae / GRBs bursts
• burst signals in coincidence with signals in
  electromagnetic radiation
• prompt alarm ( one hour) with neutrino detectors
• Pulsars in our galaxy periodic
• search for observed neutron stars (frequency,
  doppler shift)
• all sky search (computing challenge)
• r-modes
• Cosmological Signals stochastic background

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Chirp Signalbinary inspiral
determine

• distance from the earth r
• masses of the two bodies
• orbital eccentricity e and orbital inclination i

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Interferometer Data40 m prototype
Real interferometer data is UGLY!!! (Gliches -
known and unknown)
LOCKING
NORMAL
RINGING
ROCKING
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The Problem
How much does real data degrade complicate the
data analysis and degrade the sensitivity ??
Test with real data by setting an upper limit on
galactic neutron star inspiral rate using 40 m
data
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Clean up data stream
Effect of removing sinusoidal artifacts using
multi-taper methods
Non stationary noise Non gaussian tails
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Inspiral Chirp Signal
Template Waveforms matched filtering 687
filters 44.8 hrs of data 39.9 hrs arms
locked 25.0 hrs good data sensitivity to our
galaxy h 3.5 10-19 mHz-1/2 expected rate
10-6/yr
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Optimal Signal Detection
Want to lock-on to one of a set of known signals

• Requires
• source modeling
• efficient algorithm
• many computers

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Detection Efficiency

• Simulated inspiral events provide end to end
  test of analysis and simulation code for
  reconstruction efficiency
• Errors in distance measurements from presence of
  noise are consistent with SNR fluctuations

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Results from 40m Prototype
Loudest event used to set upper-limit on rate in
our Galaxy R90 lt 0.5 / hour
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Setting a limit
Upper limit on event rate can be determined from
SNR of loudest event Limit on rate R lt
0.5/hour with 90 CL e 0.33 detection
efficiency An ideal detector would set a
limit R lt 0.16/hour
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Astrophysical Sourcessignatures and data analysis

• Compact binary inspiral chirps
• NS-NS waveforms are well described
• BH-BH need better waveforms
• search technique matched templates
• Supernovae / GRBs bursts
• burst signals in coincidence with signals in
  electromagnetic radiation
• prompt alarm ( one hour) with neutrino detectors
• Pulsars in our galaxy periodic
• search for observed neutron stars (frequency,
  doppler shift)
• all sky search (computing challenge)
• r-modes
• Cosmological Signals stochastic background

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Burst Signal supernova
gravitational waves
ns
light
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Supernovae gravitational waves
Non axisymmetric collapse
burst signal
Rate 1/50 yr - our galaxy 3/yr - Virgo cluster
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Supernovae asymmetric collapse?

• pulsar proper motions
• Velocities -
• young SNR(pulsars?)
• gt 500 km/sec

• Burrows et al
• recoil velocity of matter and neutrinos

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Supernovaesignatures and sensitivity
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Astrophysical Sourcessignatures and data analysis

• Compact binary inspiral chirps
• NS-NS waveforms are well described
• BH-BH need better waveforms
• search technique matched templates
• Supernovae / GRBs bursts
• burst signals in coincidence with signals in
  electromagnetic radiation
• prompt alarm ( one hour) with neutrino detectors
• Pulsars in our galaxy periodic
• search for observed neutron stars (frequency,
  doppler shift)
• all sky search (computing challenge)
• r-modes
• Cosmological Signals stochastic background

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Periodic Signalsspinning neutron stars

• Isolated neutron stars with deformed crust
• Newborn neutron stars with r-modes
• X-ray binaries may be limited by gravitational
  waves

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Periodic Signalspulsars sensitivity

• Pulsars in our galaxy
• non axisymmetric
• 10-4 lt e lt 10-6
• science neutron star precession interiors
• narrow band searches best

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Astrophysical Sourcessignatures and data analysis

• Compact binary inspiral chirps
• NS-NS waveforms are well described
• BH-BH need better waveforms
• search technique matched templates
• Supernovae / GRBs bursts
• burst signals in coincidence with signals in
  electromagnetic radiation
• prompt alarm ( one hour) with neutrino detectors
• Pulsars in our galaxy periodic
• search for observed neutron stars (frequency,
  doppler shift)
• all sky search (computing challenge)
• r-modes
• Cosmological Signals stochastic background

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Stochastic Background cosmological signals
Murmurs from the Big Bang signals from the
early universe
Cosmic microwave background
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Stochastic Backgroundsensitivity

• Detection
• Cross correlate Hanford and Livingston
  Interferometers
• Good Sensitivity
• GW wavelength ? 2x detector baseline? f ? 40 Hz
• Initial LIGO Sensitivity
• ? ? 10-5
• Advanced LIGO Sensitivity
• ? ? 5 10-9

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Stochastic Backgroundcoherence plots LHO 2K
LHO 4K
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Stochastic Backgroundcoherence plot LHO 2K LLO
4K
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Stochastic Backgroundanalysis in progress

• Analytic calculation of expected upper limits
  (50 hrs)
• W 2 x 105 for LLO-LHO 2k, W 6 x 104 for LHO
  2k-LHO 4k
• Coherence measurements of GW channels show little
  coherence for LLO-LHO 2k correlations
• Power line monitor coherence investigations
  suggest coherence should average out over course
  of the run
• Plan to investigate effect of line removal on LHO
  2k-LHO 4k correlations (e.g., reduction in
  correlated noise, etc.)
• Plan to inject simulated stochastic signals into
  the data and extract from the noise
• Plan to also correlate LLO with ALLEGRO bar
  detector
• ALLEGRO was rotated into 3 different positions
  during E7

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Stochastic Background projected sensitivities
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LIGOconclusions

• LIGO construction complete
• LIGO commissioning and testing on track
• Engineering test runs underway, during period
  when emphasis is on commissioning, detector
  sensitivity and reliability. (Short upper limit
  data runs interleaved)
• First Science Search Run first search run will
  begin during 2003
• Significant improvements in sensitivity
  anticipated to begin about 2006

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Finis
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Planned Detector Modificationsactive external
seismic
BSC
HAM
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Advanced Detector RD and Advanced LIGO

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Advanced LIGO RD Status

• Working toward construction proposal to Fall 2002
• bottoms-up costing has nearly been completed
• Plan assumes construction funding available
  1Q2005
• some long lead funds in 1Q2004
• Supports an installation start of 4Q2006
• Soon ready to confront scope decisions (number of
  interferometers, trimming features to control
  costs, etc.)
• Advanced RD program is proceeding well
• GEO and ACIGA teams forming strong international
  partnership

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Advanced LIGO RD Status

• Interferometer Sensing Control (ISC)
• GEO 10m proof of concept experiment
• Preparation proceeding well
• Results available for 40m Program in early 2003
  (lock acquisition experience, sensing matrix
  selection, etc.)
• 40m Lab for Precision Controls Testing
• Infrastructure has been completed (i.e. PSL,
  vacuum controls envelope, Data Acquisition
  system, etc.)
• Working on the installation of the 12m input MC
  optics and suspensions, and suspension
  controllers by 3Q02
• Gingin facility for High Power Testing
• Within the next year the LIGO Lab will deliver
  two characterized sapphire test masses and a
  prototype thermal compensation system (beam scan
  and/or ring heater)
• The facility development is advancing nicely
• Activities closely linked with subsystem, LASTI
  RD plan

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Advanced LIGO RD Status

• Seismic Isolation system (SEI)
• Development of pre-isolation system accelerated
  for use in retrofit on initial LIGO
• hydraulic electro-magnet actuation variants
• To be tested at the LASTI facility
• Technology Demonstrator system has been
  fabricated
• a two stage, 12 degree of freedom active, stiff,
  isolation system
• being installed into the Stanford Engineering
  Test Facility (ETF)

• LASTI infrastructure has been completed
  (including BSC stack to support pre-isolation
  full scale testing for initial LIGO)

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Advanced LIGO RD Status

• Suspension System (SUS)
• Complete fused-quartz fiber suspensions
  functioning in the GEO-600 interferometer
• Progress, in theory and in experiment, on both
  circular fibers (tapered) and ribbons
• Dynamics testing is underway on a quadruple
  pendulum prototype
• Silica-sapphire hydroxy-catalysis bonding looks
  feasible silica-leadglass to be explored
• Significant design work underway for triple
  suspensions
• TNI nearing final results for fused silica
  sapphire mirrors ready in Fall 2002 for next phase

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Advanced LIGO RD Status

• Core Optics Components (COC)
• New optical homogeneity measurements along the
  a crystal axis are close to acceptable (13nm
  RMS over 80mm path length)
• Tests to compensate for optical inhomogeneity if
  required, look promising (computer controlled
  spot polishing and ion beam etching)
• Recent sapphire annealing efforts are encouraging
  (reductions to 20 ppm/cm vs a requirement of 10
  ppm/cm)
• Coatings on large optics show sub-ppm losses
  (SMA/Mackowski)
• Coating mechanical loss program in full swing
  materials rather than interfaces seem to be the
  culprit