Transmission Monitor System (TMS)

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

Also called "beam reducing telescope (BRT)" in LCGT.

Contents

Scope

Transmission monitors for IR/Green beams.

Collect 1064nm and 532nm light transmitting ETMs.
Monitor the off-centering and pitch/yaw fluctuations of the ITMs/ETMs relative to the preselected optical path.
Monitor the shape of the beam modes that transmit the arm cavity.

For each TMS,

2QPDs for 1064nm are required to monitor off-centering of the beam; one is for high gain, the other is for low gain.
2QPDs for 1064nm are required to monitor pitch/yaw misalignments of the beam; one is for high gain, the other is for low gain.
2QPDs for 532nm are required.
Remote stirring mirrors for QPDs are required at least in the initial commissioning phase.
Remote actuators for TMS chassis would be required.
CCD monitors for monitoring the beam mode transmitting the ETM are required.
Optical levers (or equivalent local monitors) are required.
Suspension system will require more signal channels?
Shutters for high gain QPDs are required.

For each TMS,

Name	Type	Input ch#	Output ch#	Purpose	Used By
QPD1H	1064nm QPD	0	4	Mon. off-centering, high gain	MIF
QPD1L	1064nm QPD	0	4	Mon. off-centering, low gain	MIF
QPD2H	1064nm QPD	0	4	Mon. misalignment, high gain	MIF
QPD2L	1064nm QPD	0	4	Mon. misalignment, low gain	MIF
QPD1G	532nm QPD	0	4	Mon. off-centering, low gain	MIF
QPD2G	532nm QPD	0	4	Mon. misalignment, low gain	MIF
Stirring mirrors for QPDs	TBD	24	0	Remote stirring mirrors for QPDs; 6x2x2ch	MIF
CCD monitor1	TBD, for 1064nm	On/Off?	VIDEO signal?	CCD monitor	---
CCD monitor2	TBD, for 532nm	On/Off?	VIDEO signal?	CCD monitor	---
Shutters	TBD	2	0	On/Off of shutters for high-gain QPDs	MIF

For each TMS suspension and local sensors,

TBD