Differences between revisions 5 and 16 (spanning 11 versions)

Dither-based Alignment Sensing and Stabilization

Contents

Dither-based Alignment Sensing and Stabilization
Overview
Control Topologies
1. Conceptual Designs
  1. Inline Arm Alignment
  2. Perpendicular Arm Alignment
Actual Installations and Operations
ilog and elog entries

Overview

The idea is to dither (in pitch and yaw) all of the interferometer optics. We then read out the power (arm powers, PRC power, etc.) and demodulate at the dither frequencies. We can then feedback to control the full interferometer alignment. The concept is the same as what we use to do the initial alignment of the interferometer. It was previously tried by Valera and Bram, but never worked for some reason...
- [attachment:ass.png Conceptual Diagram]
- See also the old Alignment Sensing and Control.

Control Topologies

Conceptual Designs

Inline Arm Alignment

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.

Perpendicular Arm Alignment

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.

Diagram for digital dither alignment scheme of the DRFPMI attachment:40mASC.pdf

Actual Installations and Operations

Realtime control model

Put a diagram of the real time control model

Adjustment of Input/Output Matrices

Describe how the adjustment have done.

Input signals

The input signals to ASS are:

PD1

TRX

PD2

TRY

PD3

POX33I

PD4

POY33I

PD5

SP166Q

PD6

SPOB66

PD7

AP DC

PD8

PO DC
These are displayed on the ASS MASTER display.

How to run ASS auto-scripts

```
 How to do it
```

ilog and elog entries

[http://www.ldas-sw.ligo.caltech.edu/ilog/pub/ilog.cgi?group=40m&date_to_view=02/09/2007&anchor_to_scroll_to=2007:02:10:00:50:51-valera initial commissioning]
[http://www.ldas-sw.ligo.caltech.edu/ilog/pub/ilog.cgi?group=40m&date_to_view=02/05/2007&anchor_to_scroll_to=2007:02:05:17:53:08-rward Input signals] -- mapping of signals into ASS PD's
[http://www.ldas-sw.ligo.caltech.edu/ilog/pub/ilog.cgi?group=40m&date_to_view=02/05/2007&anchor_to_scroll_to=2007:02:05:15:03:18-rward compiling the front end code]

-  ⇤ ← Revision 5 as of 2011-12-19 21:47:23 → 
  Size: 3499
  Editor: KiwamuIzumi
  Comment:
+   ← Revision 16 as of 2011-12-19 21:59:32 → ⇥
  Size: 3677
  Editor: KiwamuIzumi
  Comment:
-Deletions are marked like this.
+Additions are marked like this.
 Line 1:
-= Alignment Sensing & Stabilization system =
+= Dither-based Alignment Sensing and Stabilization  =
 Line 5:
- . This is a dither based system. The idea is to dither (in pitch and yaw) all of the interferometer optics. We then read out the power (arm powers, PRC power, etc.) and demodulate at the dither frequencies. We can then feedback to control the full interferometer alignment.

 . The concept is the same as what we use to do the initial alignment of the interferometer. It was previously tried by Valera and Bram, but never worked for some reason...
+ . The idea is to dither (in pitch and yaw) all of the interferometer optics. We then read out the power (arm powers, PRC power, etc.) and demodulate at the dither frequencies. We can then feedback to control the full interferometer alignment. The concept is the same as what we use to do the initial alignment of the interferometer. It was previously tried by Valera and Bram, but never worked for some reason...
-Line 12:
+Line 10:
-== Input signals ==
+== Conceptual Designs ==
=== Inline Arm Alignment ===
 . 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.
 Line 14:
-The input signals to ASS are:
+ . attachment:DC_ASC_Inline.png
 Line 16:
-|| '''PD1''' ||  TRX    ||
|| '''PD2''' ||  TRY    ||
|| '''PD3''' ||  POX33I ||
|| '''PD4''' ||  POY33I ||
|| '''PD5''' ||  SP166Q ||
|| '''PD6''' ||  SPOB66 ||
|| '''PD7''' ||  AP DC  ||
|| '''PD8''' ||  PO DC  ||
+    .  '''Figure 1'''. Diagram of the 40m IFO in-line arm cavity (XARM). The PRM and BS are omitted for clarity.
-Line 25:
+Line 18:
-These are displayed on the ASS MASTER display.
+ . '''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. ||
-Line 27:
+Line 28:
-= ilog entries =
+=== Perpendicular Arm Alignment ===
 . 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. ||


 . {i} Diagram for digital dither alignment scheme of the DRFPMI attachment:40mASC.pdf



= Actual Installations and Operations =
== Realtime control model ==
 . Put a diagram of the real time control model

== Adjustment of Input/Output Matrices ==
 . Describe how the adjustment have done.
=== Input signals ===

 . The input signals to ASS are:

 || '''PD1''' ||  TRX    ||
 || '''PD2''' ||  TRY    ||
 || '''PD3''' ||  POX33I ||
 || '''PD4''' ||  POY33I ||
 || '''PD5''' ||  SP166Q ||
 || '''PD6''' ||  SPOB66 ||
 || '''PD7''' ||  AP DC  ||
 || '''PD8''' ||  PO DC  ||

 . These are displayed on the ASS MASTER display.


== How to run ASS auto-scripts ==
 . {{{ 
 How to do it
}}}

= ilog and elog entries =
-Line 32:
+Line 80:
-[[BR]]
[[BR]]
-----
= Thoughts in Early Time =
 . 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. ||

----

Diagram for digital dither alignment scheme of the DRFPMI
attachment:40mASC.pdf

PD1	TRX
PD2	TRY
PD3	POX33I
PD4	POY33I
PD5	SP166Q
PD6	SPOB66
PD7	AP DC
PD8	PO DC