Optical Lever (Room Temperature)

Related subgroups: VIS, IOO, MIF, VAC, CRY...

..Up

Scope

Sensing local motions including longitudinal dof and all alignment dofs (pitch, yaw and roll) of any mirrors supported by vibration isolation system.

Note on the operating temperature: here the system is assumed to be utilized at room temperature, not in cryogenic temperature.

Applicable Documents

TBD; just see the links below.

General Description

Naming Conventions

TBD

Locations

• BS chamber
• ITM chambers (X,Y)
• ETM chambers (X,Y)
• PRC chambers (PRC, PR2, PR3)
• SRC chambers (SRC, SR2, SR3)
• MC chambers (MC1, MC2...)

Requirements

• Sensor noise should be less than xxx.
• Sensor's dynamic range should be greater than xxx.
• At least horizontal degrees of freedom (X,Y)
• Preferably a vertical sensor (Z) and side
• The sensors have to be rigidly mounted on the ground so that these are useful for remembering the position of the mirror and recording the drifts.

Characteristics

Each optical lever consists of a sensor part, a frontend circuit, and a human interface software.

The sensor part consists of the following parts: a light source, optical fibers, a focusing telescope, viewport windows, a detector, and pylons which support the focusing telescope and the detector.

The frontend circuit is TBD. Maybe we need analog cables (and what kind of connector should we use?), whitening filters and antialiasing filters. Maybe the matrix circuit will be realized using the digital systems, but in commissioning phase, we will need analog matrix.

The human interface software is TBD, which shows the mirrors' dofs monitored by Optical Levers.

Light source

For the light source, proposed candidates are

• superluminous LED (SLED) or
• laser light source as LIGO.

Optical Fibers

Optical fibers

Focusing Telescopes

Inspection plans

TBD

Procurement process and plans

TBD

Links

Some of the LIGO documents listed below are NOT public; to access them, you may need your own LSC account.

• LIGO-M1000343, Advanced LIGO Review Committee Report: Test Mass Optical Lever FDR

• LIGO-T1000517, Optical levers Final Design Review for test masses, recycler mirrors and HAM optical benches

• LIGO-G1100961, Long-Term Stability Test for aLIGO Optical Levers

• JGW-­G1100418, LCGT vacuum chamber envelope study

• LIGO-T1000533, Super-luminescent LED 21 and 50 day trend analysis

• LIGO-T1000390, Trade-off Study for the Optical Lever Light Source

• LIGO-T1000219, Test mass optical levers preliminary design