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In the diagrams the dither signals to the optics are in the YAW axis of the optics, but this is done in a similar manner in the PIT axis. The labels in the colored boxes are the channels (shown in YAW, but valid for PIT as well) to which the obtained error-signals, from the demodulation, are fed back to.
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    . '''Figure 1'''. Diagram of the 40m IFO in-line arm cavity (XARM).     .  '''Figure 1'''. Diagram of the 40m IFO in-line arm cavity (XARM). The PRM and BS are omitted for clarity.
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'''Labels - Figure 1:''' '''In-line cavity legend - Figure 1:'''
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|| L.O. ITMx || Modulation of the ITMx in PIT or YAW using tdssine. ||
|| L.O. ETMx || Modulation of the ETMx in PIt or YAW using tdssine. ||
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    . '''Figure 2'''. Diagram of the 40m IFO perpendicular arm cavity (YARM).     .  '''Figure 2'''. Diagram of the 40m IFO perpendicular arm cavity (YARM).
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'''Perpendicular Labels:''' '''Perpendicular arm legend - Figure 2:'''
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|| L.O. ITMy || Modulation of the ITMy in PIT or YAW using tdssine. ||
|| L.O. ETMy || Modulation of the ETMy in PIt or YAW using tdssine. ||


  • Design and ASC scheme after we design one for AdvLIGO
  • Implement and test the new InGaAs, in-vac, high power, FTC WFS. The 40m WFS need not be

    • in-vac, but they should be packaged as such.
  • Measure spring stuff



  • This file attachment:40m.pdf contains some results for the 40m ASC sensing matrix.

The input for this calculation was taken from 40m web page: http://www.ligo.caltech.edu/~ajw/40m_upgrade.html. The loss per optic was increased from 37.5 ppm to more realistic 100 ppm.

DC Alignment

Below are two diagrams which illustrate the proposed method to align the 40m IFO while it is locked. Currently the controls are done using Perl scripting.

In the diagrams the dither signals to the optics are in the YAW axis of the optics, but this is done in a similar manner in the PIT axis. The labels in the colored boxes are the channels (shown in YAW, but valid for PIT as well) to which the obtained error-signals, from the demodulation, are fed back to.

attachment:DC_ASC_Inline.png

  • Figure 1. Diagram of the 40m IFO in-line arm cavity (XARM). The PRM and BS are omitted for clarity.

In-line cavity legend - Figure 1:

IP_POS

Otherwise known as PZT1, located in front of the PRM. Steers the beam into the IFO.

IP_ANG

Otherwise known as PZT2, located after IP_POS and before the PRM. Also, steers the beam into the IFO.

ITMx

The ITM of the x-arm, ITMX.

ETMx

The ETM of the x-arm, ETMX.

PDH-err

The demodulated length control signal, C1:LSC-XARM_IN1.

TRX

The transmitted power of the x-arm, C1:LSC-TRX_OUT.

L.O. ITMx

Modulation of the ITMx in PIT or YAW using tdssine.

L.O. ETMx

Modulation of the ETMx in PIt or YAW using tdssine.

attachment:DC_ASC_Perp.png

  • Figure 2. Diagram of the 40m IFO perpendicular arm cavity (YARM).

Perpendicular arm legend - Figure 2:

BS

Beamsplitter, steers the beam into the perpendicular arm cavity (y-arm).

ITMy

The ITM of the y-arm, ITMY.

ETMy

The ETM of the y-arm, ETMY.

PDH-err

The demodulated length control signal, C1:LSC-YARM_IN1.

TRY

The transmitted power of the y-arm, C1:LSC-TRY_OUT.

L.O. ITMy

Modulation of the ITMy in PIT or YAW using tdssine.

L.O. ETMy

Modulation of the ETMy in PIt or YAW using tdssine.

Alignment_Sensing_and_Control (last edited 2012-01-03 23:03:06 by localhost)