Post on 14-Jan-2016
description
GEO600
Harald LückHarald LückRuthe, 4.9.2003
Worldwide Interferometer Network
Laser
Optical Layout
Michelson Interferometer
Output Mode Cleaner
Mode Cleaners
600m 10 W 5 W
1 W
~ 5 kW
10 kW atBeam Splitter
~50mW
Light power (specs)
GEO 600 Sensitivity (specs.)
Tunable SensitivityS
trai
n se
nsiti
vity
[1/
sqrt
(Hz)
]
Frequency [Hz]
Therm. noise
TMSR = 0,1%
TMSR = 1%
TMSR = 5%
Laser
Light Power (current)
Michelson Interferometer
Output Mode Cleaner
Mode Cleaners
10W 1W
300W atBeam Splitter
2W
~10mWMode Cleaners:
Troughput 80% 72%
Finesse 2700 1900
Visibility 96% 92%
R=98.65%
Power Recycling Cavity:
Mode matching 97%Finesse 450Linewidth 270 Hz
Optical Layout
Main Interferometer
Mode Cleaner
Laser Bench
Output Bench
Slave
Master
Master
Slave
entrance to vacuum system
Laser SystemMaster Laser:
Nd:YAG NPRO (non-planar ring
oscillator) 800mW @ 1064 nm
Slave Laser:
Nd:YAG injection-locked ring
cavity 14 W @ 1064nm less than 5% in higher
modes
GEO Triple Pendulum Suspension
active
passive
STS2
D-space
Thermal Noise Issues Monolithic Suspension
Silicate (Hydroxy- Catalysis) Bonding
WeldGlas Fibres (coated)
Intermediate mass
Mirror
Frequency and Length Control
MichelsonInterferometer
Output Mode Cleaner
Laser
Mode Cleaners25 MHz13 MHz37 MHz
Laser Frequency Stabilisation:
no rigid reference cavity
laser is directly stabilised to suspended cavities
3 sequential Pound- Drever-Hall control loops
common mode of the Power-Recycled Michelson
serves as frequency reference
Mode Cleaners
Output Mode Cleaner
Michelson Length Control
MichelsonInterferometer
Laser
15 MHz
10 MHz
Differential arm length:(gravitational wave signal)
heterodyne detection Schnupp modulation
round trip arm difference ~10cm
Signal-Recycling control:
separate modulation frequency
reflected beam from beam splitter AR coating
UGF ~400Hz
Reaction Pendulum:
3 coil-magnet actuators at intermediate mass
range ~100µm
Test Mass Actuators
<10Hz
>10Hz
Electrostatic actuation on test mass bias 500V, range 0-800V= 4µm
Alignment Control
differential wave-front sensing
spot position control
4 degrees of freedom at MC 1
+4 at MC 2+4 at MI (common mode)+2 at MI (differential mode)+2 at Signal-Recycling cavity
16 + 20 = 36
Alignment Control
Fast AAFast
AA
Fast AA
Magnet/coil actuators on IM
UGF: ~10Hz
Diff. MI Fast Auto-Alignment
Output port
Reduces misalignment below 50 nrad rms
Reliable locking over long timescales. Duty cycle >98%
Detector control is done with analog electronics and supervised by a digital LabView system (~200 control loops, ~1000 channels)
-Pre-alignment, Auto-alignment, Drift control-Lock acquisition-Operator interactions
System Control
GEO sensitivity during S1 runS1: 17days, Aug02-Sep02, longest lock: 121h, duty cycle 98.5%
Fall 2002: Exchanged last test optics for final optics
Final Optics Installation
Output mode
Radii Of Curvature of folding mirrors do not match
East ROC: 687m
North ROC: 666m
Spec: 640m
Thermal adjustment of ROC
+-
Thermal adjustment of ROC (II)
15 W10 W
15 W30 W
15 W51 W
15 W60 W
15 W60 W
15 W
71 W
15 W74 W
Fall 2002: Implementation of Signal Recycling mirror
Final Optics Installation
- VxWorks/Tornado based DAQ- 24-bit ADC interface: 32 + (2*) 16
channels up to 16kSample/sec- 12-bit ADC interface: 64 channels
with 512 Sample/s- LabView system acquires
~ 1000 channels @ ~1Hz- ca . 60 GB/day
Data Acquisition
Data Acquisition System
LabView detector control
DAQ computer
raw data
GEO site Hannover
raw data
detector status database
frame data
frame maker
frame data
tape writer
data collecting units (DCUs)
Radio Link
Capacity:
3 days
Data Analysis Network
frame data
Hannover (13 nodes) burst analysis, DCR,
GEO++ monitorshigh mass inspiral
Berlin tape archive
Cardiff tape archive
Golm (180x2 nodes) cw analysis
burst analysis
Glasgow (24 nodes)
directed pulsar searchBayesian burst search
B‘ham(100x2 nodes) pulsar normal modes,
GW background,inspiral
Cardiff (64 nodes)
inspiral, periodicand bursts analysis
HDD capacity 100days
LAL
amplitude
phase accumulator
phase increment register
modulo 2
sine table
GPS time
Control computer
digitalPLL
sign
4 MHz
1 PPS
data acquisitionsystem
divider
GPS antenna
Multiplication
toIFO
50 kHz
optical isolation
1 PPS
Microcontroller
50 kHz
DDS (direct digital synthesiser) phase error of less than 1% (of a full cycle) on timescales of months, recoverable from interruptions
Hardware injection of simulated cw signals
Tour Guides
Dr. Morag Casey
Labview Control
Dr. Hartmut Grote
Control, Aligment
Uta Weiland
Data related issues
Dr. Michael Plissi
Stefan Goßler
Suspension
Dr. Kasem Mossavi
Vacuum