40m Progress, LSC meeting, 3/03 1LIGO-G030033-00-R

40m Laboratory UpgradeProgress Report

Osamu Miyakawa, Caltech40m Technical Advisory Committee

LIGO-G030033-00-R

Primary objective: full engineering prototype of optics control scheme for a dual recycling suspended mass IFO, as close as possible to the Advanced LIGO optical configuration and control system

40m Progress, LSC meeting, 3/03 2LIGO-G030033-00-R

Advanced LIGO technical innovations tested at 40m

a seventh mirror for signal recycling » length control goes from 4x4 to 5x5 MIMO

detuned signal cavity (carrier off resonance) pair of phase-modulated RF sidebands

» frequencies made as low and as high as is practically possible » unbalanced: only one sideband in a pair is used» double demodulation to produce error signals

short output mode cleaner » filter out all RF sidebands and higher-order transverse modes

offset-locked arms » controlled amount of arm-filtered carrier light exits asym. port of BS

DC readout of the gravitational wave signal

Much effort to ensure high fidelity between 40m and Adv.LIGO!

40m Progress, LSC meeting, 3/03 3LIGO-G030033-00-R

Differences betweenAdvLIGO and 40m prototype

Initially, LIGO-I single pendulum suspensions will be used» No room for full scale AdvLIGO multiple pendulums – to be tested at LASTI» Scaled-down versions to test controls hierarchy in 2004?

Only commercial active seismic isolation » STACIS isolators in use on all test chambers, providing ~30 dB of isolation from 1-100 Hz» No room for anything like full AdvLIGO design – to be tested at LASTI

LIGO-I 10-watt laser, negligible thermal effects» Other facilities will test high-power laser (LASTI, Gingin)» Thermal compensation also tested elsewhere

Small (5 mm) beam spot at TM’s; stable arm cavities» AdvLIGO will have 6 cm beam spots, using less stable cavities» 40m can move to less stable arm cavities if deemed useful

Arm cavity finesse at 40m chosen to be = to AdvLIGO» Storage time is x100 shorter» significant differences in lock acquisition dynamics, in predictable ways

Control RF sidebands are 33/166 MHz instead of 9/180 MHz» Due to shorter PRC length» Less contrast between PRC and SRC signals

40m Progress, LSC meeting, 3/03 4LIGO-G030033-00-R

Target sensitivity of AdvLIGO and 40m prototype

40m Progress, LSC meeting, 3/03 5LIGO-G030033-00-R

Milestones Achieved as of Spring LSC Meeting

The characterization of the mode cleaner performance, and its interaction with the pre-stabilized laser system, occupied much of fall 2002. By the end of December 2002, the noise performance of the system met specifications.

The intensity stabilization system (ISS) for the pre-stabilized laser continues to be developed and installed.

The Global Diagnostics System (GDS), including DTT, AWG, and DMT have been installed, and DTT/AWG is in use.

Five new temperature-controlled vacuum bake ovens were commissioned in the South Annex of the laboratory, and many bake jobs were completed and qualified.

8 of 10 digital suspension controllers for suspended optics were completed by the end of calendar 2002. ETM ｘ and ETMy remain to be completed.

All 10 core optics were produced, polished, and coated, and their optical properties measured by LIGO engineers, by August 2002.

All of the mechanical suspensions for the core optics for the main dual recycled interferometer were designed, fabricated, cleaned and baked.

40m Progress, LSC meeting, 3/03 6LIGO-G030033-00-R

Milestones Achieved as of Spring LSC Meeting

Sensor/actuators (OSEMs) for the all the suspended optics were assembled, cleaned and baked, tested, and prepared for installation.

Three core optics (Beamsplitter, ITMx, and ITMy) were suspended and damped in February 2003. Four remain to be suspended by the summer 2003.

Remaining optical sensing equipments of AP, SP & MC, ITMx, ITMy, TRx, TRy were assembled and installed on the optical tables in February 2003.

Several key auxiliary systems (the in-vacuum Faraday isolator, the in-vacuum mode matching telescope with off-axis parabolic mirrors, the in-vacuum PZT steering mirror system, and the optical lever zoom telescope system) were designed, and components procured, by the end of 2002. They are now being assembled.

40m Progress, LSC meeting, 3/03 7LIGO-G030033-00-R

Lock stability of 13meter MC

Digital controlled suspensions. Smooth Lock acquisition (within

5sec). Robust lock.

39 hours lock with detection mode

MC

ref

lect

ed p

ower

Jan.10/2003 17PM – Jan.12/2003 8AM

MC

tran

smit

ted

pow

er

40m Progress, LSC meeting, 3/03 8LIGO-G030033-00-R

Measured open loop T.F. of MC

Calculated gains obtained by Rana’s model on Matlab agree with measurements.

Unity gain frequency=67.2kHz (design:over 100kHz) Phase margin=28.4deg Phase delay on total loop at high

frequency limits the unity gain frequency.

Cross over frequency=26.6Hz Phase delay on Mirror loop by

A/D converter (ICS110B).

fixed!

12/23/2002

-150

-100

-50

0

50

100

150

Pha

se[d

eg]

10-1

100

101

102

103

104

105

Frequency[Hz]

200

150

100

50

0

Mag[

dB

]

Calculated Mirror loop gainCalculated VCO loop gainCalculated total loop gainMeasured Mirror loop gainMeasured VCO loop gainMeasured total loop gain

C=10dB, B=16dB, L=30.4dBUnity gain freq.=67.2kHzPhase margin=28.4degCross over freq.=26.6Hz

Open loop transfer function of Mode Cleaner

40m Progress, LSC meeting, 3/03 9LIGO-G030033-00-R

Improvement of PSL frequency noise measured by 13-meter MC

Meets the requirement except for low frequency and bump around 600Hz.

10-3

10-2

10-1

100

101

102

103

104

Fre

quen

cy n

oise

[Hz/

Hz1/

2 ]

101

102

103

104

105

Frequency[Hz]

10/07/2002 First measurement10/17/2002 Ground loop10/21/2002 Use feedback signal11/09/2002 Turn off HEPA filter12/16/2002 Increment of PMC gain12/23/2002 Increment of Length gain01/22/2003 Vibration of PSL tablePSL Requirement

Improvement of PSL frequency noise measured by MC (Jan.22,2003)

1

23

5

4

67

40m Progress, LSC meeting, 3/03 10LIGO-G030033-00-R

10-6

10-5

10-4

10-3

10-2

10-1

100

101

102

103

104

105

106

107

108

Fre

qu

en

cy n

ois

e[H

z/H

z1/2

]

100

101

102

103

104

105

Frequency[Hz]

Total PSL frequency noise measured by MCSeimic noiseVCO phase noisePSL Frequency noise measured by FSSCoil driver noiseIntensity noiseFilter noise (Feedback)Shot+Detector noiseDetector noisePMC length noisePSL Requirement

Noise budget of PSL frequency noise (Mar,10,2003)

Noise budget of PSL frequency noise measured by 13m MC

Low frequency noise is limited by seismic noise of small stack of MC2.

Unknown noise around 100Hz (saturation of VCO loop?).

Beam jitter noise on PSL, Frequency noise and VCO phase noise limit the high frequency.

Coil driver noise, Intensity noise, Feedback filter noise, Shot noise and Detector noise are lower than total noise.

Frequency +Beam jitter +

VCO phase noise

Beam jitter

Satiration onVCO loop?

Seismic Noise

Bouncemode

Cross overfrequency

40m Progress, LSC meeting, 3/03 11LIGO-G030033-00-R

Estimation of PSL frequency noisefor 40m interferometer

-40dB Common Mode Rejection Ratio (CMRR) is assumed.

Measured residual frequency noise of MC and measured OLTF of MC are used.

Need more CMRR or more OLTF to reach the target sensitivity.

>>Actual estimation will be performed by single arm cavity later.

10-22

10-21

10-20

10-19

10-18

10-17

10-16

10-15

10-14

10-13

10-12

Str

ain

sens

itivi

ty[1

/Hz1/

2 ]

101

102

103

104

105

Frequency[Hz]

Contribution of PSL frequency noise (CMRR=40dB)

40m target sensitivity

Contribution of PSL frequency noise for interferometer

40m Progress, LSC meeting, 3/03 12LIGO-G030033-00-R

PSL

Detectionbench

Mo

de

Cle

an

er

BS

ITMy

ITMxS

ou

th A

rm

: Completed

Core optics

ITMx, ITMy, BS optics hung, balanced, installed, damped in February 2003

Begin commissioning of the interferometer with 1 degree-of-freedom, short Michelson

: Installing

East Arm

40m Progress, LSC meeting, 3/03 13LIGO-G030033-00-R

Further Infrastructure

AP1

SP&MC

Remaining optical sensing equipments of AP1, SP & MC, Pox, POy, POb,TRx, TRy were assembled in February 2003.

POx TRx

40m Progress, LSC meeting, 3/03 14LIGO-G030033-00-R

Next 9 months

Redesign of digital suspension controller using PCs for filtering.

Assemble, hang, and install the four core suspended optics (PRM, SRM, ETMx, ETMy) by 2Q 2003, and have them damped by the controller system.

Begin commissioning of the interferometer in stages, with 1 degree-of-freedom systems (short Michelson, Fabry-Perot arms) by 2Q 2003, even before a digital length control system is installed.

Fabricate and install auxiliary optics systems: scattered light control, initial alignment system, optical levers, video monitoring.

Fabricate and install LIGO I-like length sensing and control system.

Fabricate and install the alignment sensing and control system.

First experiments in dual recycled configuration response, lock acquisition, and control are expected to take at least a year.

40m Progress, LSC meeting, 3/03 15LIGO-G030033-00-R

2Q 2002: » All in-vacuum cables, feedthroughs, viewports, seismic stacks installed.» 13m input MC optics and suspensions, and suspension controllers.

3Q 2002:» Begin commissioning of 13m input mode cleaner.» Acquisition of most of CDS, ISC, LSC, ASC.

4Q 2002: » Core optics (early) and suspensions ready. Ten Suspension controllers. Some ISC.» Glasgow 10m experiment informs 40m program» Control system finalized

2Q 2003: » Core optics (late) and suspensions ready. » auxiliary optics, IFO sensing and control systems assembled.

3Q 2003: Core subsystems commissioned, begin experiments» Lock acquisition with all 5 length dof's, 2x6 angular dof's» measure transfer functions, noise» Inform CDS of required modifications

3Q 2004: Next round of experiments.» DC readout. Multiple pendulum suspensions?» Final report to LIGO Lab.

Milestones revisited

DoneDone

DoneDone

Done

In progressIn progress

In progressIn progress

40m Progress, LSC meeting, 3/03 16LIGO-G030033-00-R

(Some) outstanding issues and action items (40m, AdvLIGO)

Any significant changes in people’s thinking re: optical configuration, controls, CDS architecture??

166 MHz PD’s for WFS, LSC. Double demodulation(166 33 MHz). Design servo filters for LSC, ASC Detailed noise model (RSENOISE, Jim Mason) Lock acquisition studies with E2E/DRLIGO. Develop lock acquisition

algorithms, software. Triple-check thermal effects (Melody) – negligible? Output mode cleaner – will PSL-PMC-like device be adequate? (For 40m,

for AdvLIGO). Suspended? Offset-lock arms - algorithms, software. DC GW PD – in vacuum? Suspended?

We expect that LSC members, as well as students, will participate in this most interesting phase of the project.