SEI Structure Development

1
Time domain simulation forFP cavity with AdLIGO
parameters on E2E
Osamu Miyakawa, Hiroaki Yamamoto 06/28/2006
Advanced LIGO meeting

• Is it possible to control alignment with
  radiation pressure?
• Optical spring in ASC?
• Do we need test mass actuator for ASC? both ETM
  and ITM?
• Is the actuator dynamic range enough?
• Noise performance?

2
What implemented

• AdLIGO Quad suspension (Marks model 03/31/2006)
• Seismic motion on X, tY and tZ (length, pitch and
  yaw)
• Local damping (6, 3, 3 DOFs)
• Length control for M3 through M1, M2, M3
• Radiation pressure on length and alignment
• Optical instability on ASC
• M3 alignment control through M2
• WFS signals (not connected)

Main
Ref.
M0
M1
M2
M3
Z
X
Y
3
Quad suspensionwith radiation pressure (length)
Control
Control
4
Local damping
Example M0 pitch
Main
Ref.
Num. of DOF
6
M0
3
M1
M2
3
0
M3
Zero _at_ 0Hz Pole _at_ 10,10Hz
5
Optical instability in alignment
6
Test mass alignment control with radiation
pressure
ITM
ETM
ASC Control
ASC Control
Radiation pressure
Control BW 10Hz
7
Test mass alignment control with radiation
pressure
Test mass(M3) alignment can be controlled by
feedback to M2.
8
Next step

• Frequency response for ASC optical spring
• WFS signal in control loop
• Dynamic range limit of OSEM for ASC
• Noise model
• Miss-centering