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| = Arm Length Stabilization by injecting green laser beams from the arm ends = | = Arm Length Stabilization using green laser beams = [[BR]] . attachment:green_man.jpg [[BR]] . We are developing a technique of Arm Length Stabilization (ALS) for advanced LIGO. The technique employs two auxiliary green lasers at each end of the arm. Basically these lasers are able to sense the displacement of the each arm independently on the main laser, eventually make full lock acquisition of advanced interferometer more robust and reliable. [[BR]] [[BR]] |
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| [[BR]] | |
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| {i} aLIGO ALS wiki http://ilog.ligo-wa.caltech.edu:7285/advligo/Arm_Length_Stabilisation | |
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| ------- | |
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| == Plan == | == Designs and Plans == |
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| * [[Upgrade 09/GreenLock/timeline|time line]] describes where we are now and where we go. | * The time line describes where we are now and where we go. B) [[Upgrade 09/GreenLock/timeline|time line]] |
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| == Detailed design == | ==== Green Preliminary 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)>> [[BR]] ------- == Installation status == |
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| * B) [[Upgrade 09/GreenLock/Electronics|Electronics]] |
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| ==== Green Preliminary 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)>> |
. B) [[Upgrade 09/GreenLock/Control Information|jump to Control Information]] |
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| === Development roadmap === * '''End table arrangement''' * NPRO placement / optical assembly at the end |
== Links == . B) [[Upgrade 09/GreenLock/Noise Requirement|jump to Noise Requirement]] |
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| * SHG at the end table * Control system placement * Coarse alignment to the cavity * Fine alignment * Lock of the green beam to the cavity * '''At the PSL table''' * SHG at the PSL table * '''Digital control''' * Virtual Green lock by RCG * GPIB interfaces * '''Vertex tank optical arrangement''' * In-vac steering (PO transmission / Periscope / Mirrors) * Vertex phase noise measurement * Electronics placement * Control system implementation * '''Performance evaluation''' * f_noise of green beam / PDH performance * Relative f_noise between the PSL green and the Arm transmitted green * ALS performance * '''Sophistication of the scheme''' * Automatic handing off scripts * Ready-to-go panels for AdvLIGO * Automatic alignment of the green beam * --- * Green Michelson for precise ETM calibration * Absolute length / mode spacing measurement by green''' ''' ---- == Control information == [[Upgrade 09/GreenLock/Control Information|jump to Control Information]] == Noise Requirements == [[Upgrade 09/GreenLock/Noise Requirement|jump to Noise Requirement]] |
. {i} 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] |
Arm Length Stabilization using green laser beams
- attachment:green_man.jpg
- We are developing a technique of Arm Length Stabilization (ALS) for advanced LIGO. The technique employs two auxiliary green lasers at each end of the arm. Basically these lasers are able to sense the displacement of the each arm independently on the main laser, eventually make full lock acquisition of advanced interferometer more robust and reliable.
<<TableOfContents: execution failed [Argument "maxdepth" must be an integer value, not "[2]"] (see also the log)>>
Designs and Plans
time line
The time line describes where we are now and where we go.
time line
Conceptual design
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]
Green Preliminary Design
Installation status
Design and Purchasing Lists
Detailed considerations
- Optical Layout ([attachment:green_optics.png Table]/ In-vac)
Periscopes for beam steering from PR3/SR3 transmissions to the PSL viewport
- PSL viewport modification (viewport cover / tube / PSL box / periscope on the PSL table)
- PSL table
Laser & SHG specs --- power, polarization, Xtals
- references
[1] G.D.Boyd and D.A. Kleinman, [http://jap.aip.org/japiau/v39/i8/p3597_s1 "Parametric interaction of Focused Gaussian Light Beams", J.A. Phys. 39, 3597 (1968)]
[2] C. Zhang, Y.Qin and Y.Zhu, [http://www.opticsinfobase.org/ol/abstract.cfm?uri=ol-33-7-720 "Perfect quasi-phase matching for the third-harmonic generation using focused Gaussian beams",Opt. Lett. 33, 720 (2008)]
- Main optics specs (review)
- Mode matching ([attachment:modematch_END.png mode matching at end table])
- Green generation
- [attachment:manual_oven.pdf manual for the covesion oven]
- Expected performance / noise / control system range
- Digital servo / operation
- Alignment (initial / fine / automatic)
- Optical Layout ([attachment:green_optics.png Table]/ In-vac)
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]