Differences between revisions 17 and 18

Optical Characterization

This page is intended for summarizing the interferometer optical characterization results and discussions. See following pages and documents for iKAGRA and bKAGRA Phase-1 characterization summary:

See following pages for some design parameters

RF Sidebands

f1 frequency: 16.8732705 MHz https://klog.icrr.u-tokyo.ac.jp/osl/?r=4831
f2 frequency: 44.995388 MHz https://klog.icrr.u-tokyo.ac.jp/osl/?r=4831
f1 modulation depth:
f2 modulation depth:

Input Mode Cleaner

Round-trip length
- Design: 53.28708 m (FSR of 5.6269873 MHz)
- Measured: 53.302985(9) m
- Measurement method: FSR was measured to be 5.624308(1) MHz. https://klog.icrr.u-tokyo.ac.jp/osl/?r=4831
- Notes: Measured on April 2018. Any re-installation after this? Needs to be adjusted to match with PRC length.
Finesse
- Design: 520
- Measured: 409
- Measurement method: Cavity pole was measured to be 6.86(2) kHz. https://klog.icrr.u-tokyo.ac.jp/osl/?r=14569
- Notes: Lower than iKAGRA measurement of 540+/-70 http://klog.icrr.u-tokyo.ac.jp/osl/?r=618 Degraded?
Mode-match
- Measured:
- Measurement method:
- Notes:

Arm Cavities

X-arm length
- Design: 3000 m
- Measured: 2999.990(2) m
- Measurement method: Cavity scan FSR = 49.96557(4) kHz http://klog.icrr.u-tokyo.ac.jp/osl/?r=7332
- Notes:
X-arm Gouy phase
- Design: 250.75 deg
- Measured: 250.7(3) deg
- Measurement method: Cavity scan TMS=34.79(5) kHz http://klog.icrr.u-tokyo.ac.jp/osl/?r=7332
- Notes:
X-arm finesse for IR
- Design: 1530
- Measured: 1410(30)
- Measurement method: Ring down
- Notes: There is temperature dependence due to frosting https://klog.icrr.u-tokyo.ac.jp/osl/?r=10033
X-arm round-trip loss
- Design: 100 ppm
- Measured: 86(3) ppm
- Measurement method: From reflectivity change in locked and unlocked https://klog.icrr.u-tokyo.ac.jp/osl/?r=7307
- Notes: The estimate might be wrong due to birefringence https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=11633
X-arm mode-match
- Measured: 91(1)%
- Measurement method: Cavity scan https://klog.icrr.u-tokyo.ac.jp/osl/?r=7307
- Notes:
X-arm finesse for green
- Design: 51
- Measured: 41(2)
- Measurement method: Calculated from reflectivity measurements by Hirose-san
- Notes:
Y-arm length
- Design: 3000 m
- Measured: 3000.015(1) m
- Measurement method: Cavity scan, FSR = 49.96517(2) kHz https://klog.icrr.u-tokyo.ac.jp/osl/?r=9505
- Notes:
Y-arm Gouy phase
- Design: 250.75 deg
- Measured: 250.9(3) deg
- Measurement method: Cavity scan, TMS = 34.82(5) kHz https://klog.icrr.u-tokyo.ac.jp/osl/?r=9505
- Notes:
Y-arm finesse for IR
- Design: 1530
- Measured: 1320(30)
- Measurement method: Ring down, http://klog.icrr.u-tokyo.ac.jp/osl/?r=9052, http://klog.icrr.u-tokyo.ac.jp/osl/?r=9211, http://klog.icrr.u-tokyo.ac.jp/osl/?r=9496
- Notes: There is temperature dependence due to frosting https://klog.icrr.u-tokyo.ac.jp/osl/?r=10033
Y-arm round-trip loss
- Design: 100 ppm
- Measured: NOT YET MEASURED?
- Measurement method: https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=11633
- Notes:
Y-arm mode-match
- Measured: 87(2) %
- Measurement method: Cavity scan https://klog.icrr.u-tokyo.ac.jp/osl/?r=9505
- Notes:
Y-arm finesse for green
- Design: 51
- Measured: 53(3)
- Measurement method: Calculated from reflectivity measurements by Hirose-san
- Notes:

Power Recycling Cavity

PRX length
- Design: 68.2563 m (PRC length = 66.591 m)
- Measured: 68 m
- Measurement method: Using dnu/nu=dL/L https://klog.icrr.u-tokyo.ac.jp/osl/?r=14633
- Notes: Compare it with PRY.
PRY length
- Design: 64.9265 m
- Measured: 70.2 m
- Measurement method: Using dnu/nu=dL/L https://klog.icrr.u-tokyo.ac.jp/osl/?r=14565
- Notes: In consistent results between different methods and not compatible with Schnupp asymmetry measurement
PRC Gouy phase
- Design: 33.0 deg
- Measured: 31(1) deg
- Measurement method: Cavity scan with the inertia locking method http://klog.icrr.u-tokyo.ac.jp/osl/?r=9276
- Notes: After PR2 was moved.

Signal Recycling Cavity

SRX length
- Design: 68.2563 m (SRC length = 66.591 m)
- Measured:
- Measurement method:
- Notes:
SRY length
- Design: 64.9265 m
- Measured:
- Measurement method:
- Notes:
SRC Gouy phase
- Design: 35.0
- Measured: 48(2)
- Measurement method: Cavity scan with the inertia locking method http://klog.icrr.u-tokyo.ac.jp/osl/?r=9246
- Notes:

Michelson

Schnupp asymmetry
- Design: 3.3299 m
- Measured: 3.36(1) m
- Measurement method: Demodulation phase difference in locking X-arm and Y-arm https://klog.icrr.u-tokyo.ac.jp/osl/?r=14575
- Notes: Not consistent with PRX and PRY measurements.

Dual Recycled Michelson

Power recycling gain
- Design:
- Measured: ~3
- Measurement method: REFERENCE TO BE ADDED
- Notes:
Power at each ISC detection ports when DRFPMI is locked
- IMC output:
- REFL:
- POP p-pol:
- POP s-pol:
- POS p-pol:
- POS s-pol:
- AS RF:
- OMC REFL:
- OMC TRANS:
- TRX:
- TRY:

Power Recycled Fabry-Perot Michelson

Power recycling gain
- Design: 10
- Measured: 11-12
- Measurement method: REFERENCE TO BE ADDED
- Notes:
Power at each ISC detection ports when PRFPMI is locked
- IMC output:
- REFL:
- POP p-pol:
- POP s-pol:
- POS p-pol:
- POS s-pol:
- AS RF:
- OMC REFL:
- OMC TRANS:
- TRX:
- TRY:

Output Mode Cleaner

Round-trip length
- Design: 1.5 m
- Measured: 2 * 0.717(2) m = 1.434(4) m
- Measurement method: Cavity scan FSR of 208.99(65) MHz https://klog.icrr.u-tokyo.ac.jp//?r=14696
- Notes:
Finesse
- Design: 780
- Measured: 616(62)
- Measurement method: Cavity scan https://klog.icrr.u-tokyo.ac.jp//?r=14696
- Notes:
AS mode content

Sensing Matrix Measurements

Optical Tables

I think we need a power budget here.

KAGRA/Subgroups/MIF/OpticalCharacterization (last edited 2021-08-11 16:03:32 by YutaMichimura)

-  ⇤ ← Revision 17 as of 2021-02-26 23:10:01 → 
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+   ← Revision 18 as of 2021-02-26 23:11:59 → ⇥
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+ * AS mode content

== Sensing Matrix Measurements ==
 * LSC

 * ASC