Global control using a laser strainmeter for KAGRA Kouseki Miyo - - PowerPoint PPT Presentation

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Global control using a laser strainmeter for KAGRA Kouseki Miyo - - PowerPoint PPT Presentation

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Global control using a laser strainmeter for KAGRA Kouseki Miyo Sep 9, 2019, TAUP2019 at Toyama Contents 3000 m 500 m 1500 m 1000 m X arm Y arm Laser Strainmeter 1. Introduction 2. Strainmeter of KAGRA 3. Sensor Correction Technique

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SLIDE 1

Global control using a laser strainmeter for KAGRA

Kouseki Miyo

Sep 9, 2019, TAUP2019 at Toyama

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SLIDE 2

Contents

2

3000 m 500 m 1500 m 1000 m X arm Y arm Laser Strainmeter

  • 1. Introduction
  • 2. Strainmeter of KAGRA
  • 3. Sensor Correction Technique
  • 4. First trial
  • 5. Results
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SLIDE 3

Seismic noise under ground

3

  • K. Yamamoto, JGW-T1000218, (2010)

Earth Tides
 ~100 um
 ~10-5 Hz) Microseismic Wind, trafic, human activity

In lower frequencies, reduction is not so much.

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SLIDE 4

4

klog:9386

TM IM MN 99th 90th 50th

* * * TestMass (TM) Intermediate
 Mass (IM) MarionetteMass (MN)

* Y. Michimura, et. al., (2017)

Actuator range and seismic noise

The range is enough, but small actuator range potentially limits the duty cycle of KAGRA.

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SLIDE 5

5

  • Strainmeter can FeedForward the seismic motion

to the arm to reduce the feedback force.

2nd floor 1st floor 3 km 1.5 km

IX EX

Strainmeter

X arm

Global Control Feedback

Global Control on the Arm cavity

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SLIDE 6

In the case of LIGO

6

4 km

EX

Arm

Local Control

  • Seismometers can also measure the

arm fluctuation.

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SLIDE 7

NLVDT NSTRAIN (Trillium120Q) NSEIS

7

  • However, seismometers can not measure

the ground motion below 80 mHz.

  • The strainmeter can measure below that.

Seismometers and Strainmeter

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SLIDE 8

8

  • A. Araya et. al., (2017)

Earth Tides (KAGRA strainmeter) Microseismic

  • Strainmeter can measure almost all seismic

motion in low frequency.

Bandwidth of the Strainmeters

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SLIDE 9

Strainmeter of KAGRA

sin cos

＋ΔL

  • ΔL

Front Reflector End Reflector HWP QWP

cos sin

p - polarized s - polarized

circular - polarized PBS

Frequency Stabilized Laser

ΔL

1500 m

  • Quadrature phase

detection

  • Rotation indicates arm

length changes

  • Wide dynamic range

9

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SLIDE 10

The strainmeter

10

KAGRA X arm Stand Alone DAQ End Reflector KAGRA X arm Frequency Stabilized Laser Front Chamber Center 
 Area

X End Me

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SLIDE 11

Sensor Correction Technique

11

Hs Sff Cfb Csc Cff Pa Sfb XGND(EX) Nff Nfb r

  • +

(r=0) HTM

+

  • XSTG

XTM

+

  • XGND(IX)

where,

XGND

IP Actuator

XSTG

Position sensor XTM(EX) Strainmeter

  • Test Mass
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SLIDE 12

Sensor Correction Technique

12

Hs Sff Cfb Csc Cff Pa Sfb XGND(EX) Nff Nfb r

  • +

(r=0) HTM

+

  • XSTG

XTM

+

  • XGND(IX)

where,

If G is high and SC will subtract, 
 EX follow IX by using SC.

XGND

IP Actuator

XSTG

Position sensor XTM(EX) Strainmeter

  • Test Mass
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SLIDE 13

Sensor Correction Technique

13

Hs Sff Cfb Csc Cff Pa Sfb XGND(EX) Nff Nfb r

  • +

(r=0) HTM

+

  • XSTG

XTM

+

  • XGND(IX)

If G is high and SC will subtract, 
 EX follow IX by using SC.

XGND

IP Actuator

XSTG

Position sensor XTM(EX) Strainmeter

  • Test Mass

1 1

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SLIDE 14

Sensor Correction Technique

14

Hs Sff Cfb Csc Cff Pa Sfb XGND(EX) Nff Nfb r

  • +

(r=0) HTM

+

  • XSTG

XTM

+

  • XGND(IX)

If G is high and SC will subtract, 
 EX follow IX by using SC.

XGND

IP Actuator

XSTG

Position sensor XTM(EX) Strainmeter

  • Test Mass
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SLIDE 15

Sensor Correction Technique

15

Hs Sff Cfb Csc Cff Pa Sfb XGND(EX) Nff Nfb r

  • +

(r=0) HTM

+

  • XSTG

XTM

+

  • XGND(IX)

If G is high and SC will subtract, 
 EX follow IX by using SC.

XGND

IP Actuator

XSTG

Position sensor XTM(EX) Strainmeter

  • Test Mass
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SLIDE 16

Sensor Correction Technique

16

Hs Sff Cfb Csc Cff Pa Sfb XGND(EX) Nff Nfb r

  • +

(r=0) HTM

+

  • XSTG

XTM

+

  • XGND(IX)

If G is high and SC will subtract, 


XGND

IP Actuator

XSTG

Position sensor XTM(EX) Strainmeter

  • Test Mass

We can make the EX follow the IX motion!

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SLIDE 17

First trial

17

  • Correction signal was feedforwarded to the EX

suspension point. The singnal was injected in all frequencies.

  • No arm length control to the test mass. The FP

was locked by the feedback loop to the AOM.

Laser Feedback Signal Not use Correction Signal

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SLIDE 18

OFF ON

Worked!

E a r t h T i d e

Result

18

  • Slow motion was subtracted from FeedBack signal
  • High frequency motions are not seemed so.
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SLIDE 19

Higher frequency band

19

  • Noise was injected


(~ 0.8 Hz)
 →Need lowpass filter

  • No big difference in

RMS, because of a peak at 150 mHz.

RMS (ON) RMS (OFF)

We need more investigation

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SLIDE 20

Summary

  • Actuator range is limited near the test mass not to

introduce electric noises on the GW signal.

  • Unlike seismometers, the laser strainmeter has an

advantage to measure the change of arm length

  • directly. It also covers frequency range where

seismometers cannot measure the ground motion accurately.

  • Sensor correction technique using strainmeter

can make the EX test mass follow the IX test mass motion.

  • We need more investigation to improve the

subtraction

20

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SLIDE 21

Backup

21

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SLIDE 22

Frequency Stabilized Laser

22

BS2 BS1 PBS2 PBS1 FI Iodine cell AOM QWP Stabilized Light +

  • AM

FM 97 kHz 6 kHz Absorption Signal Derivative Signal Pump Prob

p - polarized s - polarized

Nd:YAG

PZT TMP