Arm Length Stabilization by injecting green laser beams from the arm ends

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

Plan

time line

• time line describes where we are now and where we go.

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 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

Detailed design

• Design and Purchasing Lists

  • Optical design / item list

  • Electronics / control design / item list

  • Purchase list

• Detailed considerations

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

    • ETM / end table

    • ITM wedge effect

    • 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)

Control information

jump to Control Information

Noise Requirements

jump to Noise Requirement