AIGO High Performance Compact Vibration Isolation System

1
AIGO High Performance Compact Vibration Isolation
System
Eu-Jeen Chin, Jean-Charles DumasSchool of
Physics, The University of Western Australia,
Nedlands, WA 6907, Australia
Vibration Isolation Techniques
Testing and Performance of Prototype Isolator

• The AIGO vibration isolator combines several
  techniques.
• Anti-Springs in most stages reduce mode
  frequencies.
• The Pre-isolator combines two horizontal stages,
  an inverse pendulum and a Roberts Linkage, and
  one vertical LaCoste stage, all with resonant
  frequencies below 0.1Hz.
• The inverse pendulum.
• The LaCoste linkage provides vertical
  pre-isolation.
• The Roberts linkage.

Inverse pendulum
Roberts Linkage

• A prototype of the AIGO isolator was completed in
  2004, and has been tested in air.
• Each stage and control system was tested
  individually.
• Results agree with predicted performance.

LaCoste stage
Euler stage
Self-Damped pendulums
Roberts Linkage Frequency Response Tuning of
the load point
3 Stage Horizontal Frequency Response
40
Control mass
20
0
Test mass
-20
dB
-40

• The isolation chain consists of three similar
  stages.
• 40kg pendulums with Euler spring vertical
  suspensions.
• Each stage comprises a rocker mass and self
  damped pendulum with eddy current damping.

-60
-80
0.2
0.5
1
2
5
Frequency (Hz)
Theoretical Full Chain Frequency Response
Theoretical Full Chain RMS Residual Motion
5
-
10
0
10
-
10
100
-
15
-
10
200
-
dB
RMS Res. Motion (Hz)
20
-
10
300
-
25
-
10
400
-
30
-
10
0.01
0.02
0.05
0.1
0.2
0.5
1
2
5
10
20
50
0.01
0.1
1
10
Frequency (Hz)
Frequency (Hz)
Roberts Linkage
Double wire suspended on a pivot, free to swing.
Progress at AIGO

• Assembly of two complete vibration isolators at
  the AIGO test facility.
• All components cleaned and baked.
• Optical cavity differential motion testing in
  AIGO East arm planned late 2005.

40kg Rocker mass, high moment of inertia.
Pivot
Viscous
damping
Euler Stage
Self-Damping Schematic
Integrated 3D isolator stage

• Local control implemented at pre-isolation stage
• Coil and magnet actuation for positioning and
  damping for both the inverse pendulum and LaCoste
  stages.
• Slow vertical control by coil spring heating in
  the LaCoste stage for thermal drift and creep
  correction.
• Slow position control using the Roberts linkage
  by heating suspension wires.