Modeling of Alignment Sensing and Control for Advanced LIGO

Document #:

LIGO-T0900511-v4

Document type:

L - Letters and Memos

Abstract:

This note presents a model of the alignment sensing and control scheme for Advanced LIGO. The model has been realized with the frequency domain tool Optickle,
which has the peculiarity of including radiation pressure effects.
The optical configuration studied here corresponds to the Advanced LIGO baseline
as at August 2009. In particular, stable recycling cavities are considered.

Files in Document:

• T0900511_v4.pdf (3.6 MB)

Topics:

• Modelling
• Sensing and Control

Authors:

• Matthew Evans
• Lisa Barsotti

Keywords:

Advanced LIGO ASC

Notes and Changes:

- More realistic cut off of damping loops for the suspensions
- Frequency dependent SRC mirror coupling to DARM
- Better approx of the convolution for computing the noise coupling to DARM
- Computation of the SRC mirrors coupling to DARM due to beam angular motion
- Plot of beam angular motion and beam spot motion for the SRC mirrors as seen by the OMC
- Gouy phase values relative to the IFO mirrors (in appendix)

Referenced by:

• LIGO-G1200632-v3: Towards Applied Heirarchical Control
• LIGO-E1200171: aLIGO, ISC, ASC
• LIGO-G1500923-v1: The Advanced LIGO Angular Control System (ASC) (Hanford edition)
• LIGO-T1600397-v2: Beam Position from Angle to Length coefficients
• LIGO-E1200170: aLIGO, ISC, ISC