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= Green Laser Injection for Arm Pre-Lock = <<Anchor(TOP)>>
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We plan to install green lasers, which are phase locked to the PSL laser, at each end station to pre-lock the arm cavities before the lock acquisition.    . attachment:god_of_green.png
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== Basic Concept ==
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== Noise Requirement ==
I'd say the arm cavity length should not change more than 1/100 of the resonance width in the time scale of 10sec.[[BR]]
For this to be fulfilled, the RMS fluctuation of the cavity length must be suppressed below 1e-11m level.[[BR]]
Does this make sense ?
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=== Noise Sources ===
==== PLL phase noise ====
==== Phase noise from the cavity common mode motion ====
When the cavity is locked to the green laser, the differential motion of the two mirrors will be suppressed by the servo.
However, the common motion of the cavity mirrors will not be suppressed. This common motion will show up as phase noises of the lasers. The time derivative of phase noise is equivalent to frequency noise. The equivalent displacement noise seen by the cavity is dL=(w*x*L)/c, where w is the angular frequency, x is the displacement noise spectrum of the common motion, L is the length of the cavity and c is the speed of light (see [attachment:PhaseNoise.pdf] for derivation).

= Overview and Conceptual design =

   <<ImageLink(green_vertex_preliminary_design.png,Upgrade 09/GreenLock/Preliminary design for the vertex,height=200)>>
   <<ImageLink(green_ETM_preliminary_design.png,Upgrade 09/GreenLock/Preliminary design for the end,height=200)>>

= plans =

[[BR]]

= developer's page =

||''' Optical Layout '''|| ([attachment:green_optics.png Table]/ In-vac) ||
|| ''' end table ''' || [[Upgrade 09/GreenLock/end table|ETM / end table]] ||
|| ''' end table ''' || <<ImageLink(endtable.jpg,Upgrade 09/GreenLock/end_table)>> ||
|| ''' wedge effect ''' || [[Upgrade 09/Optical Layout#wedge|ITM wedge effect]] ||
|| ''' in-vac ''' || [[Upgrade 09/Optical Layout|Periscopes for beam steering from PR3/SR3 transmissions to the PSL viewport]] ||
|| ''' Mode matching ''' || ([attachment:modematch_END.png mode matching at end table]) ||
|| ''' Electronics ''' || [:Upgrade 09/GreenLock/Electronics] ||
|| ''' sensing and control ''' || [[Upgrade 09/GreenLock/Control Information|jump to Control Information]] ||
  


= links =
|| ''' aLIGO ALS wiki ''' || http://ilog.ligo-wa.caltech.edu:7285/advligo/Arm_Length_Stabilisation ||
|| ''' Description of the optical / servo configuration ''' || [https://dcc.ligo.org/cgi-bin/private/DocDB/ShowDocument?docid=6888 LIGO DCC] ||
|| ''' Servo modeling (!SimLink) ''' || [https://nodus.ligo.caltech.edu:30889/svn/trunk/docs/upgrade08/Green_Locking/Servo_modeling/ 40mSVN] ||
|| ''' manual for the doubling oven ''' || [attachment:manual_oven.pdf manual for the covesion oven] ||
|| ''' noise requirements ''' ||[:Upgrade 09/GreenLock/Noise Requirement] ||
|| ''' purchase list ''' || [[Upgrade 09/Purchase List/Green Locking|Purchase list]] ||

  • attachment:god_of_green.png

Overview and Conceptual design

  • green_vertex_preliminary_design.png green_ETM_preliminary_design.png

plans

BR

developer's page

Optical Layout

([attachment:green_optics.png Table]/ In-vac)

end table

ETM / end table

end table

endtable.jpg

wedge effect

ITM wedge effect

in-vac

Periscopes for beam steering from PR3/SR3 transmissions to the PSL viewport

Mode matching

([attachment:modematch_END.png mode matching at end table])

Electronics

[:Upgrade 09/GreenLock/Electronics]

sensing and control

jump to Control Information

links

aLIGO ALS wiki

http://ilog.ligo-wa.caltech.edu:7285/advligo/Arm_Length_Stabilisation

Description of the optical / servo configuration

[https://dcc.ligo.org/cgi-bin/private/DocDB/ShowDocument?docid=6888 LIGO DCC]

Servo modeling (SimLink)

[https://nodus.ligo.caltech.edu:30889/svn/trunk/docs/upgrade08/Green_Locking/Servo_modeling/ 40mSVN]

manual for the doubling oven

[attachment:manual_oven.pdf manual for the covesion oven]

noise requirements

[:Upgrade 09/GreenLock/Noise Requirement]

purchase list

Purchase list

Advanced_Techniques/Green_Locking (last edited 2015-06-23 03:44:00 by EricquinteroATligoDOTorg)