The AEI 10m Prototype Interferometer

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15 Νοε 2013 (πριν από 3 χρόνια και 6 μήνες)

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DPG spring meeting, March 2011

The AEI 10m Prototype Interferometer

Tobias
Westphal

for the AEI 10 m Prototype
team

http://10m
-
prototype.aei.uni
-
hannover.de

Why

to

build

another

PT

M
aximal

overlap with GEO
-
HF subsystems


Develop and prove as many of the techniques needed for gravitational wave detector
upgrades as possible (e.g. laser, digital control infrastructure)


Provide training for people who will install upgrades to and run GEO
-
HF

2

Ultra
-
low displacement
-
noise test environment


To probe at and beyond the
Standard Quantum Limit
(SQL)


equivalent Heisenberg limit for 100

g test masses


Thermal noise interferometer


Other experiments within QUEST (for e.g. LISA or GRACE follow on)


Entanglement of macroscopic test masses (a bit further down the road…)


What

is

the

SQL

3

SQL
interferometer

layout

4

Frequency


reference

cavity

Length
: 12

m

Finesse: ca. 7500

Triple

pendulum

suspension

Mirror
mass
: 860

g

10

m
Fabry
-
Perot

arm
cavity

Finesse ca. 700

100

g
Mirrors

monolithic

silica

suspensions

~8

W
@ 1064

nm

fiber

coupled

Optional:

Power
recycling

Optional:

Signal
recycling

Anti
-
resonant

Fabry
-
Perot

cavity

as compound end
mirror

Tap off

~130

mW

Squeeze
-
in tanks

5

Learn

from

experience
!


Earlier

days

(GEO600 design):


Not
very

versatile


REALLY
uncomfortable



to

work

in


Walk
-
in tanks

6

600

mm
flanges

to fit
viewports

100

mm
flanges

to fit
feed

throughs

100

mm
flanges

to fit
feed

throughs

Walk
-
in
door

Ultra
-
high vacuum system

Tanks:

3.4

m tall

3

m
•Ø

Tubes:

1.5

m Ø

7

10
-
6
mbar after
about

12
hours


100

m³ Volume


22

t
stainless

steel



170

l/s
screw

pump (
roughing
)


2x 2000

l/s
turbo

pump (
main
)


2x scroll pump (
backing

& differential)



Metal

gaskets

below

600

mm


Double O
-
ring
differentially

pumped



Sliced

open


Optical
benches

in
the

tanks


Passive
seismic

isolation


Active

inter

table

stabilisation

8

Table
subsystems

Inverted
pendulum

Base plate

Optical table

Filter support

LVDT / Actuator

Vertical
motorized

blade

Horizontal
motorized
blade

Accelerometer

Tilt
stabilisation

Geometric

antispring

9

GAS filter (
vertical

isolation
)

10

Top
view

Side
view

Featuring


very soft potential → large isolation


Huge loading capabilities

Estimated
motion

11

10
-
5
10
-
6
10
-
7
10
-
8
10
-
9
10
-
10
10
-
11
10
-
12
10
-
13
10
-
14
10
-
2
10
-
1
10
0
10
1
10
2
Frequency
[Hz]
Displacement [m/

Hz]
Ground
Horizontal
Vertical
10
-
5
10
-
6
10
-
7
10
-
8
10
-
9
10
-
10
10
-
11
10
-
12
10
-
13
10
-
14
10
-
2
10
-
1
10
0
10
1
10
2
Frequency
[Hz]
Displacement [m/

Hz]
Displacement [m/

Hz]
Ground
Horizontal
Vertical
Ground
Horizontal
Vertical
60

dB


micro
-
seismic

anthropogenic

70

dB

Vertical
isolation (measured)

12

-
90
-
80
-
70
-
60
-
50
-
40
-
30
-
20
-
10
0
1
10
100
Transfer function [dB]
Frequency [Hz]
Reference Measurement
Single Magic Wand (SiC)
7

dB

← GAS
-
resonance frequency ca. 440

mHz

off
-
centered

accelerometer

shaker structure

without magic wand

GAS filter
shaker

13

GAS filter in
action

14

Estimated
differential motion

15

10
-
5
10
-
6
10
-
7
10
-
8
10
-
9
10
-
10
10
-
11
10
-
12
10
-
13
10
-
14
10
-
2
10
-
1
10
0
10
1
10
2
Frequency
[Hz]
Displacement [m/

Hz]
Ground
Horizontal
Vertical
10
-
5
10
-
6
10
-
7
10
-
8
10
-
9
10
-
10
10
-
11
10
-
12
10
-
13
10
-
14
10
-
2
10
-
1
10
0
10
1
10
2
Frequency
[Hz]
Displacement [m/

Hz]
Displacement [m/

Hz]
Ground
Horizontal
Vertical
Ground
Horizontal
Vertical

Inter
table

Passive

isolation

Active

isolation

Low
freqency

active isolation

16

10
-
5
10
-
6
10
-
7
10
-
8
10
-
9
10
-
10
10
-
11
10
-
12
10
-
13
10
-
14
10
-
2
10
-
1
10
0
10
1
10
2
Frequency
[Hz]
Displacement [m/

Hz]
Ground
Horizontal
Vertical
10
-
5
10
-
6
10
-
7
10
-
8
10
-
9
10
-
10
10
-
11
10
-
12
10
-
13
10
-
14
10
-
2
10
-
1
10
0
10
1
10
2
Frequency
[Hz]
Displacement [m/

Hz]
Displacement [m/

Hz]
Ground
Horizontal
Vertical
Ground
Horizontal
Vertical

Stabilized


inter

table

Passive

isolation

Active

isolation

Accelerometers

LVDT`s


SPI


Suspension
platform

interferometer

Goal:


Stabilize inter table motion


100

pm/√Hz, 10

nrad
/√Hz


@ 10

mHz


Based on LISA Pathfinder experience:


Heterodyne Mach
-
Zehnder

interferometer with unequal arm
length (by 23

m)


Iodine
-
stabilised
Nd:YAG

(frequency noise)


Optics bonded onto low CTE plate
(thermal drifts)


Digital
signal

processing

(FPGAs)

17

Digital
control

system


Based

on
realtime

LINUX


Runs EPICS
software

18

Experiment

Sensors &
actuators

Fieldboxes

Signal
conditioning

AA/AI
filters

ADC/DAC

6 x 32channel

PCI
-
X

DA/AD & DIO

Front
-
end

Digital
filters

Analog
world

Digital
world


Gives

error

signals


Carries

actuation

out



Changes


Get

data

GPS

timing

Storage

Frame
builder

Workstation

User
world


/4

/2
NPRO
Isolator
Nd:YVO
crystals
4
pump
optics
Laser: 35

W @ 1064

nm

Crystals:


3 x 3 x 10

mm
3

Nd:YVO4


8 mm 0,3

% doped, 2

mm
endcap

Frequency

[FSR]


24

W
measurement



TEM
00

model




Normalized

power

Pump diode:


808

nm, 45

W


400

µm
Ø

fiber

coupled
,

NA=0,22

Amplifier:


38

W for
2

W seed and 150

W pump

19

99% in
TEM
00

Mirror

suspensions

Frequency reference cavity:


Three horizontal, two vertical stages


850

g per stage (mirror 10

cm x 5

cm)


Steel wires, last stage 55

µm Ø


Local control and alignment control at
uppermost stage


(fast alignment is done at steering mirrors)


Interferometer optics:


Three horizontal stages, two vertical stages


100

g per stage (mirror ca. 2“ x 1“)


All silica last stage, 4 filaments of 20

µm Ø


20


Sensitivity

w/o
Khalili

cavities

21

High
reflective

coatings

have

lots
of

coating

layers

(1)
Few

layers



medium R, low CTN

(2)
Many layers



high R, high
CTN


Let‘s separate reflectivity and losses!

Where does coating noise appear?

22

N

Coating

noise

N

R
eflectivity

Khalili

cavity

23

EETM

IETM

One

HR
mirror



two

mirrors:


1.
Medium reflectivity:

ca. 50

%

(IETM
)

2.
High reflectivity:

99.99

%
(
EETM
)

(2n+1)




Factor

1.6
reduction

of

coating

thermal
noise

Sensitivity

w/o
Khalili

cavities

24

Sensitivity

with

Khalili

cavities

25

Sensitivity

with

doping

& Khalili

26

The team

27

Ken Strain:
Scientific leader

Stefan
Goßler
:
Coordinator

Gerhard
Heinzel
:
LISA/LPF related experiments

Yanbei

Chen,
Kentaro

Somiya
, Stefan
Danilishin
:
Experiment design, noise

analysis

Roman Schnabel:
Squeezing and QND experiments

Harald

Lück
:
Vacuum system and GEO 600 related experiments

Hartmut

Grote:
Electronics and GEO 600 related experiments

GEO operators
:
Filter design and construction, environmental monitoring

Andreas Weidner:
Electronics design

Kasem

Mossavi
:
Vacuum system and pumps control

Jens
Breyer
:
Mechanical design

Benno

Willke
, Jan
Hendrik

Pöld
, Christina
Bogan
:

High power laser

Gerrit

Kühn
, Michael Born, Martin
Hewitson
:
Real time control system

Alessandro
Bertolini
, Alexander
Wanner
:
Isolation tables

Katrin

Dahl:
SPI

Fumiko

Kawazoe:

Frequency reference cavity

Stefan
Hild
, Sabina
Huttner
, Christian
Gräf
:

Interferometric

sensing & control

Giles Hammond, Tobias
Westphal
:

Monolithic suspensions

Gerald Bergmann:
Commissioning




http://10m
-
prototype.aei.uni
-
hannover.de


28