LSC-March-2001 1

LIGO End to End simulation Lock acquisition design

» How to increase the threshold velocity under realistic condition

» Hanford 2k simulation setup

» Lock acquisition, real and simulated

In-lock state noise simulation» Seismic, thermal and shortnoise

» Simulate sensitivity curve

Detector operation support Future plan - LIGO I and advanced LIGO

Status of End to End modelLSC Meeting at LLO on March 16th, 2001

Hiro Yamamoto / LIGO Lab @ Caltech

LIGO-G010176-00-E

LSC-March-2001 2

End to End simulation

Simulation engine - like matlab» Time domain simulation framework written in C++» Tools for IFO simulation» Field calculation based on a time domain modal model» Basic tools ready

LIGO Simulation program - like m file of matlab» Han2k

– suspended core optics with LSC (Matt’s code)

– Customizable for 4k IFO by editing a database text file

Application for LIGO» LIGO lock acquisition design» LIGO base noise curve

seismic, thermal and shotnoise

LSC-March-2001 3

Hanford 2k IFOLock Acquisition

Matt Evans Design of FP lock

» realistic controller, smart logic

Han2k - LIGO simulation program built using e2e» scalar field model

» 6 suspended mirror

» seismic motion

Data vs simulation

LSC-March-2001 4

Fabry-Perotideal vs realistic

idea

lre

alis

tic

Linear Controllers:Realistic actuationmodeling plays acritical role incontrol design.

+z

z=0

Psus

Popt

zVdamp

sig_MASSzFopt

V

I150mA

LSC-March-2001 5

Fabry-PerotError signal linearization

S SPDHAtr

2 rETMtETM

2 sin

LSC-March-2001 6

Hanford 2k simulation setup

Han2k optics setup

EtmR

ItmR

EtmTItmTBSRec

trr

trtpob

potasyref

Leng_ArmR

Leng_ArmT

Leng_Rec2BS

Leng_BS2ItmR

Leng_BS2ItmT

por

lower - lower sideband powerupper - upper sideband powercarrier - lower sideband power

I - inphase demodulated signalQ - quadphase demodulated signal

photo detector and demodulator

powers of each frequency

Field data

P - total power

power meter

PSL/IOO

LSC-March-2001 7

Automated Control Matrix SystemLIGO T000105 Matt Evans

Control system

Signal toDOF

DOF toOptics

PtrtPtrr

QaymIasm

QpobIPobQrefIref

sig_EtmT

sig_EtmR

sig_ItmT

sig_ItmR

filters

L-

L+

l-

l+

errLm

errLp

errlm

errlp

sig_L-

sig_L+

sig_l-

sig_l+

DOF gainconLm

conLp

conlm

conlp

gainEtmT

gainEtmR

gainItmT

gainItmR

optical gainField signal

Actuation of mass

Same c code usedin LIGO servo

and in simulation

LSC-March-2001 8

Multi step locking

State 1 : Nothing is controlled. This is the starting point for lock acquisition.

State 2 : The power recycling cavity is held on a carrier anti-resonance. In this state the sidebands resonate in the recycling cavity.

State 3 : One of the ETMs is controlled and the carrier resonates in the controlled arm.

State 4 : The remaining ETM is controlled and the carrier resonates in both arms and the recycling cavity.

State 5 : The power in the IFO has stabilized at its operating level. This is the ending point for lock acquisition.

LSC-March-2001 9

Lock acquisitionreal and simulated

obse

rvab

le

Not

exp

erim

enta

lly

obs

erva

ble

LSC-March-2001 10

What’s new» Fully time domain» Full simulation of locked Interferometer» Based on “measured” signals, not on analytic formulas

Seismic noise» seismic motion + stack transfer function (Ed Daw) + pendulum

Thermal noise» wire and internal (Kent, Sam)»

Shotnoise» noise generated based on the input power on the photo detector» non stationary effect and mixing angle dependence calculated

Use “measured transfer function” to convert to sensitivity

In-lock state noise simulation

z(t) z0(t)zTN (t)

LSC-March-2001 11

Noise of one mirrorseismic & thermal

Hz

LSC-March-2001 12

Average number of photons

Actual number

Photo detector by detector

Detector noiseShotnoise

n0(t) P(t)th

n(t) Poisson(n0 (t))

(1) Off(2) Simplified(3) Full simulation

LSC-March-2001 13

L- control force for low frequency

Quad-demodulated signal from dark port for high frequency

Simulated sensitivity byL- control and Quad asym

dVdz

( f ) A( f 2 af /Q f02 )

ddz

( f ) B

1 f2

f02

, f0 172Hz

LSC-March-2001 14

Simulated sensitivity curve

Hz

L- control

dark port error signal

input power is 1W

LSC-March-2001 15

Shotnoise contribution

Hz

with shotnoise

without shotnoise

input power is 1W

LSC-March-2001 16

In-lock state noise simulationCommissioning support

Coupling of length and angular controls and actuation Propagation of noises Study of lock stability Non stationary phenomena Optimization of servo settings …

LSC-March-2001 17

Future workLIGO I

Software / Physics» In-lock state noise

– Seismic noise

– Thermal noise

– Generate combined noise

» Simple 3D mirror

» WFS» Validation of modal model code

» Simple PSL/IOO for L+ feedback

» Radiation pressure

» Thermal effect

» New optics model

» Integration of MSE

» Mirror aberration by higher order mode

Software / C++» Parallelization using thread

» Save & Load

» Multiple time step

» Improvements of tools– Macros, Funcs

System / LHO-LLO» Full 6x6 (3x3) stack

– Including validation

» IFO / site specific – Seismic motion– Mechanical properties– Optical properties

LSC-March-2001 18

Future workAdvanced LIGO

Optics» Summation cavity of dual recycling configuration

– Malik

» Thermal lensing / thermo-elastic– Calculation of the (physical and optical) deformation of optics– Calculation of fields with those deformed objects– Melody

Mechanics» Simulation of quad pendulum

– MSE vs matlab

» Interfacing with existing tools