'''[[LCGT/subgroup/ifo/ISC/TaskList|..Up]]'''


= Link to Relevant documents =
 As of April 2019
 * [[ https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=10137 |Final design and implementation document]]
 * [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=7769 | Document tree for green lock]]
 * [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=8394 | ISC sysmte circuit diagram ]]
 * [[ https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=9919 | Yokogawa's master thesis on the X arm experiment ]]
 * [[ | Journal paper on the X arm experiment ]]

= Official reviews =
 * Review in March 2018 [[ https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=8103 | Material by Yokogawa et al.,]]
   Main focus on the selection of the optical fibers
 * Review in August 2017 [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=7060 | Material by Kambara et al.,]]
   Main focus on the readiness for the implementation.


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= Past Considerations (mostly back in 2012) =

== Servo simulation ==
 *  [[http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=788|Report in JGWDOC]]



== Optical Table Layout ==
 * [[attachment:GrLock_Table_120127.pdf]]

== Purchase List ==
 * [[attachment:tatsu_2012_Jan.xlsx]]

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=== SVN archive ===
[[https://granite.phys.s.u-tokyo.ac.jp/svn/LCGT/trunk/GreenLock/|SVN directory]]

=== Oscillator phase noise requirement for PLL  local oscillator ===
See [[https://granite.phys.s.u-tokyo.ac.jp/wiki/Lab/index.php?LCGTALSPhaseNoise|here]].

=== Overview of Green Lock Scheme ===
[[attachment:Overview_GreenLock.pdf]]

=== Lock procedure ===
[[attachment:Procedure.pdf|PDF]]

=== Block diagram ===
[[attachment:BlockDiagram.pdf|BlockDiagram]]

=== Description of the blocks ===
==== Phase Comparison ====
 * When you combine two beams with power P, we get the beat note with amplitude of '''2 alpha P Sin phi''', where '''alpha''' is the contrast (0~1) and phi is the relative phase between the fields. '''Thus, the phase sensitivity is 2 alpha P [W/rad]'''. e.g. Two 1mW beams geneartes 4mWpp beat if the contrast is 1. The slope is 0.002 alpha W/rad.

 * For the broadband PD, InGaAs is not relevant because of the high junction capacitance. If we use Si PD (like FFD-100 phi=2.5mm), the responsivity is '''eta = 0.08 [A/W]'''.

 * BBPD Transimepedance and the shotnoise intercept current are assumed to be 1e3 [V/A] and 0.3 [mA], from the experience of LIGO BBPD.

 * '''Total gain is 1 [V/rad]''' if we assume alpha and P to be 0.5 and 12.5mW respectively.

 * Shot noise
  * Shot noise of the modulated beam is described by <in^2> = 2 e [I0+1/2 dI Sin(phi)], according to N. Mio and K. Tsubono, Physics LettersA 164 (1992) 255-258.　Does nonstationary part cancel because of the orthogonality of the RF and LO signals???
  * Consider only the stationary part, in = sqrt(2 e I0). Thus in/eta/(2 alpha P) = sqrt(e / eta / alpha / P) [rad/rtHz]. This corresponds to 2.5e-8 rad/rtHz.

==== Frequency noise of NPRO ====
 * 1e4/f [Hz/rtHz] according to R. Adhikari's PhD thesis.

==== Shot noise ====
 * [[attachment:PC010706.JPG|Shot noise estimation]]