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| = Green Laser Injection for Arm Pre-Lock = | = Arm Length Stabilization using green laser beams = [[BR]] |
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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: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]] <<TableOfContents([2])>> [[BR]] ------- == Designs and Plans == === time line === * The time line describes where we are now and where we go. B) [[Upgrade 09/GreenLock/timeline|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 ==== . <<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)>> === Development roadmap === * '''End table arrangement''' * NPRO placement / optical assembly at the end * SHG at the end table * Control system placement * Coarse/fine alignment to the cavity * 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''' ''' == Installation status == == Detailed design == * '''Design and Purchasing Lists''' * Optical design / [[Upgrade 09/Purchase List/Green Locking|item list]] * Electronics / control design / [[Upgrade 09/Purchase List/Green Locking|item list]] * [[Upgrade 09/Purchase List/Green Locking|Purchase list]] * '''Detailed considerations''' * Optical Layout ([attachment:green_optics.png Table]/ In-vac) * [[Upgrade 09/GreenLock/end table|ETM / end table]] <<ImageLink(endtable.jpg,Upgrade 09/GreenLock/end_table)>> * [[Upgrade 09/Optical Layout#wedge|ITM wedge effect]] * [[Upgrade 09/Optical Layout|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 * B) [[Upgrade 09/GreenLock/Electronics|Electronics]] * Digital servo / operation * Alignment (initial / fine / automatic) == Control information == . B) [[Upgrade 09/GreenLock/Control Information|jump to Control Information]] == Links == . B) [[Upgrade 09/GreenLock/Noise Requirement|jump to Noise Requirement]] . {i} aLIGO ALS wiki http://ilog.ligo-wa.caltech.edu:7285/advligo/Arm_Length_Stabilisation |
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
Development roadmap
End table arrangement
- NPRO placement / optical assembly at the end
- SHG at the end table
- Control system placement
- Coarse/fine alignment to the cavity
- 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
Installation status
Detailed design
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)
Control information
aLIGO ALS wiki