Adv. LIGO Arm Length Stabilisation Design

Document #:

LIGO-T0900144-v3

Document type:

T - Technical notes

Abstract:

The design of the arm length fluctuation system. This system aids in the lock acquisition of the interferometer by stabilising the arm cavity length fluctuations to within ~1.3 nm.

Files in Document:

• T0900144_v3_ALS_Design.pdf (file is not accessible)

Topics:

• Final Design
• Sensing and Control

Authors:

• Sam Waldman
• Daniel Shaddock
• Bram Slagmolen
• John Miller
• Peter Fritschel
• Adam Mullavey
• David McClelland

Notes and Changes:

Have NOT updated the Quad feedback results.

Other changes are:
- Modified the introduction including the start of the discussion of using the green heterodyne beatnote signal in the vertex to phase lock the auxiliary laser to the PSL.
- Made small changes to the Approach section, and in the end removed it.
- Removed section 6 In-Vacuum-Trans-Mon-Table (was a detailed description).
- Modified section~\ref{TransmonTable} 'In-Vacuum Transmon-Table', which is a short description with refences.
- Updated 'System Overview'.
- Removed fiber phase noise cancellation implementation and results.
- Added the Single Arm Test.
- Included the RF building blocks.