= Transmission Monitor Telescopes (TMS) =
'''''Related subgroups:''''' IOO, MIF, VAC, CRY, VIS...

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

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'''[[KAGRA/Subgroups/AOS| back to AOS top]]'''
<<TableOfContents(3)>>

== Scope ==
 . Transmission monitors for IR/Green beams.

== General Description ==
=== Applicable Documents ===
 * [[http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=1122|麻生さんによるデザイン例]]

=== Functions ===
 * 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.

=== Requirements ===
 . 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.

=== List of Channels ===
 . For each TMS,
 ||<#FFFF00>Name||<#FFFF00>Type||<#FFFF00>Input ch#||<#FFFF00>Output ch#||<#FFFF00>Purpose||<#FFFF00>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,
 ||<#FFFF00>Name||<#FFFF00>Type||<#FFFF00>Input ch#||<#FFFF00>Output ch#||<#FFFF00>Purpose||<#FFFF00>Used By||
 ||Actuators for TMS||TBD||12?||0||Remote actuation for TMS||---||
 ||Optical levers for TMS||TBD||0||8||OpLev QPDx2?||---||
 ||Other, related to the suspension itself ||TBD||---||---||---||---||


=== Naming Conventions ===
 . TBD

=== Locations ===
 * At the dedicated chambers in back of ETM chambers


== External Links ==
 * [[https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=6559|LIGO-T0900511-v4, Modeling of Alignment Sensing and Control for Advanced LIGO]]
 * [[https://dcc.ligo.org/cgi-bin/private/DocDB/ShowDocument?docid=4559|LIGO-T0900385-v7, The advanced LIGO ETM transmission monitor]]
 * [[https://dcc.ligo.org/cgi-bin/private/DocDB/ShowDocument?docid=11582|LIGO-T1000247-v3, ISC Gouy phase telescopes]]
 * [[https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=62886|LIGO-E1100537-v10, Transmission Monitor Telescope Suspension (TMS) Final Design]]
 * [[https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=60926|LIGO-G1100439-v4, TMS Telescope Alignment]]
 * [[https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=58277|LIGO-T1100258-v4, Transmission Monitoring Telescope and Suspension - TMS]]