ISC Meeting on 2019/04/22 14:00 - 15:00

Participants: Koji Nagano, Yutaro Enomoto, Osamu Miyakawa, Kiwamu Izumi, Yuta Michimura (Keiko Kokeyama and Masayuki Nakano on April 23)

Zoom meeting: https://zoom.us/j/6676627462

Next meeting

2019/5/13 (Mon) 14:00-15:00 (JST) (Next Chief meeting will be on 5/7)

https://www.timeanddate.com/worldclock/meetingtime.html?day=20&month=5&year=2019&p1=248&p2=4399&p3=137&iv=0

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Minutes

Design schematic of IOO rack
- Current version at JGW-D1706814
- Circuits to come:
  - ISS 2nd loop servo (2U) and BIO breakout (1U)
  - EOM RF Amplifier for f1,f2,f3 (1U x 3) JGW-T1809211
    - EOM RF Amplifier is similar to RF Distribution Amplifier
  - One more AA for k1ioo1 to host RF sideband monitor
    - We should make a space between AA/AIs because of heat
- A/I: Make a design schematic of IOO rack based on the inputs above [Michimura]
RF sideband tuning, Removal of f2 RF generator
- MZM experiment until May 3. ISC people can tune the frequency and replace f2 afterwards. [Kokeyama]
- Tune sideband frequencies with respect to PRC. Tune IMC length if we have time
  - We might open the chamber at around September for mid-baffle, beam dumps, ISS 2nd loop PDs etc.
Cover for optical tables
- Conceptual design JGW-T1910129
- What is the purpose of the cover?
  - Light shielding. Not so much for sound proofing.
- Don't we need to fix the cover to the table rigidly so that we can move the table by cranes? LIGO does that during installations etc.
  - The cover we use is not so rigid as opposed to LIGO one.
- A/I: Check with Aso-san about the side hatch of SR2 [Michimura]
OMC PZT driver
- Requested to AEL
ITM inhomogeneity [Somiya]
- Calculated OMC DC PD and DC QPD response DCQPDresponse.pdf
- Looks not so bad.
- We might want dither ETMs to create beacon signal for OMC alignment

Agenda

Design schematic of IOO rack
- Current circuits, ISS related circuits, EOM RF amp, ... and??
- Schedule for the rearrangement
- Removal of temporary f2 RF generator (f2 should be generated by the Harmonic Generator)
RF sideband tuning
- For O3, tune with respect to PRC, and we don't not have time to tune IMC length?
- When for the tuning?
- When to stop MZM experiment?
Cover for optical table [Michimura]
- Conceptual design JGW-T1910129
OMC PZT Driver status? JGW-T1910039
Thick OSTM with wrong coating JGW-T1909937
- Specs
  - we want: 100mm dia, 30mm thick, p-pol, 45 deg, T=1%, AR<500ppm, 2 deg wedge
- 2 deg wedge OK?
ITM inhomogeneity [Somiya]
- Calculated OMC DC PD and DC QPD response DCQPDresponse.pdf
In-vac steering mirrors
- For some steering mirrors, p-pol beam
  - STM1, STM2, POM1, POM2 around IFI (PYD-20 is used)
  - steering mirrors after OFI
- PYD-20 has a transmission
  - T < 70ppm at 0 deg for s-pol (measured)
  - T < 25ppm at 30 deg for s-pol (measured)
  - T < 5ppm at 45 deg for s-pol (measured)
  - T ~ 1000pppm at 45 deg for p-pol (specsheet)
- Do we need to order steering mirrors for p-pol?
- Also, how to dump the transmitted beams of steering mirrors?
High power compatibility of REFL table
- HWP, thin film polarizer, beam dump (water cooled power meter) were used for IMC REFL
- REFL table might not have enough space
Beam shutter around OMC
- Ref: https://dcc.ligo.org/LIGO-T1100208 (PD damaged with ~50 mJ; see Fig 6)
- Ref: https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=28683 (H1 OMC damage; pulse width ~0.1s)
- Ref: https://dcc.ligo.org/LIGO-G1000489 (shutter speed ~1msec necessary)
- Advanced Virgo: three types of shutter
  - Slow shutter in front of OMC: open only when locking OMC
  - Fast shutter in between the slow shutter and OMC: Uniblitz shutter, 10msec. Digital trigger using OMC TRANS DC PD signals.
  - Fast shutter in front of DC PDs: 10msec. Digital trigger using OMC TRANS DC PD signals
- Necessity of fast unlocking of OMC?
- For KAGRA, ~120W at max to OMC on IFO unlocks
  - current driver for OMC PZT has ~200 usec delay klog #8050
  - 1msec shutter prototype already made at Titech. In-vac one to be made by summer 2019 [Somiya]
- Delay of 200usec for the driver sounds too fast. May be too noisy?
- aLIGO uses HV driver and LV driver. One PZT is driven by HV and LV, and the other PZT is driven by HV only. LV (high speed) is used for unlocking OMC.
- We should make OMC drivers ourselves.
- OMC driver delay measurement should be done end-to-end (using beam, OMC locked).
- no space in between OSTM and OMC
- slow and compact one in between OSTM and OMC?
In-vac RF PD and RF QPD
- collected info of Advanced Virgo design (RF PD from Romain from LAPP, RF QPD from Matteo from Nikhef)

Notes

Main topics for Phase-2 [Michimura]
- Fix initial alignment scheme for full IFO
  - Enomoto?
  - For XY arm JGW-G1808462
- Finalize ALS scheme and RF AM generation scheme and finalize lock acquisition scheme
  - Enomoto?
- ISC modeling, especially ASC modeling, for intermediate IFO configurations
  - Tanioka for ASC?
- Cabling diagram
  - Almost finalized JGW-D1808394
- In-vacuum RF PD and RF QPD
  - Izumi will ask LIGO people first.
  - Laser welding would be tough (resonant circuit cannot be re-tuned)
  - Use similar design to OMC DC PD preamplifier?
- Readout DC PDs and OMC
  - In-vac amplifier board made JGW-D1809177
  - Cabling diagram around OMC JGW-G1809012
- Design output optics on optical tables Output Tables Optics wiki
Thick OSTM with wrong coating JGW-T1909937
- Specs
  - we want: 100mm dia, 30mm thick, p-pol, 45 deg, T=1%, AR<500ppm, 2 deg wedge
  - we ordered: 100mm dia, 60mm thick, s-pol, 3+/-10 deg, T<100ppm, AR<500ppm, 0.3 deg wedge
  - measured: p-pol, T=3%, AR<1000ppm (klog #8049)
  - verndor calculation: p-pol, 45 deg, T=13%, AR=3%
- We concluded that we should
  - make 30mm OSTM with correct coating -> Matteo talking with Prof. Mio
  - make a suspension for 30mm thick mirror (modify TAMA MC input suspension to put OSEMs?)
  - when to replace depends on the sensitivity and timing
Black tube for AS JGW-T1909863 [Michimura]
- Design done. Under procurement. JGW-D1910037
Polarization of Optical tables
- s-pol BSs have been used for optical tables, but actually REFL and AS/OMC REFL/OMC TRANS beams were p-pol (due to IFI and OFI)
- Beam power reducing scheme for REFL requires p-pol
  - not correct! s-pol can also be used [Enomoto]
- Why don't we keep using s-pol BSs for REFL and AS? Any comments?
  - REFL: JGW-T1809238
    - Use reflection of thin film polarizer for beam power reduction
  - AS: JGW-T1909817
    - Put HWP for all the beams
AS optical table layout JGW-T1909817 [Aritomi]
- Procurement done except for 2inch BS and spares. -> ordered 2inch BSs in April 2018
- In-vac layout basically done JGW-T1909618
  - A/I: Add OMC DC PD preamp to the layout to check the position. [Somiya]
- Also wind shield for AS table
  - TAMA wind shield is done by VIT
Harmonic Generator modification plan JGW-T1909661 [Michimura]
- It outputs x30 instead of x24, and we need a switch and standard Dsub 3pin connector for DC power supply.
- AEL will take care of modification around DC power supply, including rear panel modifications
- Use a chassis without a rear panel and handmade DC power supply cable with a switch for the time being
- Replacement of RF components will be done afterwards, with AEL and MIF.
- A/I: buy RF components for the replacement [Michimura]
- Installed: klog #8095
  - Bandpass filter for 135 MHz?
- Rear panel modification done.
Sapphire mirror damage with high power klog #7931 [Hirose]
- The average threthold for coating damage is at 92 W/mm^2
- 10 W input at PRM already gives ~13 W/mm^2 at ITM/ETMs.
- Needs to consider this risk when going to higher power.
Safety guard around output optics
- shield for OMMT1, OMMT2 (~500 mW during observation with 80W input at PRM)
- beam dump for OMC REFL (~500 mW during observation with 80W input at PRM)
- high speed beam shutter, electronics for unlocking OMC (~120W at max on IFO unlocks)
  - current driver for OMC PZT has ~200 usec delay klog #8050
  - 1msec shutter prototype already made at Titech. In-vac one to be made by summer 2019 [Somiya]
Tentative OMC DC QPD Amplifier and procurement status klog #8047 [Somiya]
- Tentative OMC DC QPD amplifier was made with hacked Oplev DC QPD amplifier
- The final one will arrive at around mid-March
DRMI LSC with 3f, 70% SRM JGW-G1909595 [Enomoto]
- DRMI can be done with 3f
- f3 error signals during CARM offset change seem to be more affected by 3f. Strange.
RF PD and RF QPD tuning [Michimura]
- The number of RF PDs and RF QPDs necessary are as follows:
- RF PD
  - f1, f2: in-air 6pcs, in-vac 5pcs
    - in-air: REFL, IMMT2T, POP, POX, POY, AS
    - in-vac: REFLVAC x2, POPVAC, POXVAC, POYVAC
  - f3-f1, f3-f2: in-air 1pc (needs design)
    - in-air: REFLNRSB
  - 2*f1, 2*f2: in-air 2pcs (needs design)
    - in-air: SPOP, SPOS
  - 3*f1, 3*f2: in-air 1pc (needs design)
    - in-air: REFLTHREEF
- RF QPD
  - f1,f2: in-air 6pcs, in-vac 6pcs
    - in-air: REFL A/B, POP A/B, AS A/B
    - in-vac: REFLVAC A/B, POPVAC A/B, AS A/B
- AEL (Shimode-san) will take care of f1 and f2 PD/QPD tuning (9pcs of RF PD and 15pcs of RF QPD) JGW-L1909582
- A/I: Design in-vac housing for RF PD and RF QPD
- A/I: Design 3f, 2f (and f3) RF PD resonant/notch circuit
  - 3*f2 (135 MHz) would be tough due to the capasitance of 2mm PD. Replace PD to silicon one?
- Double peak design used in aLIGO RF PDs should be implemented in future KAGRA RF PD (see, also, LHO alog #13881)
  - LIGO-T1100402: ISC RF Photodetector Design: LSC & WFS
  - LIGO-T1400196: ISC RFPD Resonant Circuit Optimizer Code
  - LIGO-T1200506: RFPD Build Status and Locator
  - LIGO-T1300488: Guide to Troubleshooting aLIGO RFPDs
  - LIGO-T1300315: Notes on RFPD Signal Chain Measurements
  - LIGO-T1300506: aLIGO RFPD Spot Check Procedure
AS port layout JGW-T1909618 [Somiya,Michimura]
- The power of OMC REFL will be quite high (~500 mW with 80 W input, carrier TEM00 is ~20 mW).
  - Put a pick-off mirror inside the vaccum chamber to reflect 99 % of the beam to dump, and extract 1% transmission in-air.
- The power will be even higher in IFO unlocks.
  - A/I: High speed beam shutter, Analog circuit for unlocking OMC, Protectors for OMMTs and OSTM.
  - Ref: https://dcc.ligo.org/LIGO-T1100208 (PD damaged with ~50 mJ)
  - Ref: https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=28683 (H1 OMC damage; pulse width ~0.1s)
- A/I: Check AR reflectivity of viewports [Hirose]
  - -> ~1% at 45 deg
- A/I: Check if OMC TRANS is extractable from OMC mirrors [Somiya]
- A/I: Buy a pick-off mirror [Somiya]
Mach-Zehnder modulator [Yamakoh]
- Not sure if requirement calculation using Optickle is reasonable or not
  - Requirement calculated directly from the TF from MZI displacement noise to DARM and that calculated using TFs from MZI displacement to multiple f1/f2 PM/RAM amplitude/phase noise, multiplied by TFs from multiple f1/f2 PM/RAM amplitude/phase noise to DARM do not match.
- A/I:
  - Analytically calculate TFs from multiple f1/f2 PM/RAM amplitude/phase noise (LIGO-T1500559) to DARM and compare them with Optickle.
  - Analytically calculate TFs from MZI displacement to multiple f1/f2 PM/RAM amplitude/phase noise
- A/I: Look into requirement calculations again
  - Phase noise for f1 RAM, which comes from asymmetry of 1st MZI, gives the most stringent requirement
- Displacement noises of 1st and 2nd MZI do not meet the Phase 2 requirement.
- Plan for O3
  - Agree to do 3f in O3 (Minutes of the Commissioning Meeting 20190108)
  - Technical review on Jan 22
    - Displacement noise, modulation depth, residual amplitude modulation, phase noise, long term stability
    - Disassemble 1st MZI and 2nd MZI? Just block one of the arms (loose 7/8 of the power)?
    - Future plans?
- Future plans
  - Make monolithic MZM?
  - Make a wind shield?
MZM plans, list of measurements to be done [Control room meeting with Yamakoh, Kokeyama, Guiguo, Izumi, Enomoto, Miyakawa, Michimura]
- Jan 29: MZM alignment with new posts
- Jan 29-Feb 1:
  - Displacement noise measurements, coherence measurements for each optic, calibration of accelerometer signal to MZM displacement noise
  - KOACH on/off, precision air-con on/off tests
  - Preparations for long term stability measurement (80MHz mixer for modulation index measurement, temperature, polarization monitors)
- Feb 4-Feb 8 ~ Mar:
  - Preparations for long term stability measurement continued (PSL to IOO rack cabling, IQ demodulator cabling etc.)
  - IMC frequency noise measurement with MZM
- Mar 14-16: Test run for long term stability measurement
- Mar 23-24: Long term stability measurement
- Mar 30-31: Final chance for long term stability measurement
- Mar 30: Remove EOM and measure displacement noise
- April: Disassemble MZM
  - IMC frequency noise measurement without MZM
- Any time:
  - Measure actual phase difference between EOMs.
  - Offline subtraction of noises using accerelometer signals etc.
- Commissioning can be done with MZM blocked until we need high power (July), but we will disassemble MZM once we have all the measurements done.
OMC status
- OMC was locked from the digital system klog #6846
- DC PD Preamp SN1 was broken, but replaced
  - transfer function of DC PD should be measured within a few % for calibration
- DC QPD amplifier not arrived yet
- Calculations on DC power and circuit noise -> Somiya & Arai
  - Koji's calculation: DCPDCalculation
- Electronics status
  - In-vac DC PD amplifier board finalized JGW-D1809177
  - In-air DC QPD amplifier board not arrived yet
ITMY inhomogeneity JGW-T1808715
- We should check impact on sensitivity and locking as soon as possible
  - For both O3 and full bKAGRA
- There was a discussion whether we should re-optimize OMC for BRSE or DRSE without homodyne angle optimization.
- ASC simulation by FINESSE show worse signal when ITMY inhomogeniety is added (a few % degradation in shot noise?)
- higher order contents, especially odd-order modes are worse
- But still need to check the Finesse code (alignment loop not closed yet)
- FINESSE calculation on ASC was not reliable since Gouy phase tuning was not done
- Working on Gouy phase tuning
RF generation using Mach-Zehnder interferometer [Kohei Yamamoto] JGW-G1707309 JGW-G1807655 JGW-G1808029
- simulation on imperfections (MZ arm asymmetry, MZ lock, EOM phase difference control etc.)
- calculate requirements on MZI displacement, EOM modulation phase difference, EOM imbalance
- Requirements derived from full Optickle simulation and those derived from transfer function between displacement of MZI and sideband power kind of matched after implementing RAM into calculation for the latter. However, we need more investigation on the following issues:
  - Modulation depth for RAM generating EOM changes the requirement.
  - Spectrum shapes of the requirements for mid-fringe do not match. Maybe coming from accuracy of the mid-fringe?
  - Unknown frequency response of the transfer function from the displacement of MZI and sideband power
  - Check if caluculated RF oscillator amplitude noise is relative one or not with simple Optickle model
- calculations for requirements on delay line lock displacement noise, parallel EOM MZ lock displacement noise, EOM modulation phase difference, EOM imbalance on-going
- Relative f1 PM and f1 AM also needs to be adjusted (CQG 31, 095003 (2014)). Another EOM for f1 or relative amplitude adjuster between two EOMs?
- Requirement on carrier power loss?
- Comment from Stefan Ballmer
  - Similar calculation was done in LIGO in the past. Displacement noise requirement for MZ was tough (~1e-14 m/rtHz).
  - Any in-air interferometer suffer from jitter and frequency noise which cannot be suppressed.
- Ref: LIGO-T040119
- RF oscillator noise requirements for MZI should also be calculated
Other long standing tasks
- Real Low Noise VCO, also for FSS
- Fiber noise cancellation for ALS
- DC QPD holder
- IMMT1 and IMMT2 transmission
- Slow channels for monitoring things (PLC based? Beckhoff? Acromag?)

See Minutes20170410 and Minutes20190225 for other agendas.