ISC Meeting on 2019/02/25 14:00 - 15:00

Participants:

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

Next meeting

2019/3/11 (Mon) 14:00-15:00 (JST)

https://www.timeanddate.com/worldclock/meetingtime.html?day=11&month=3&year=2019&p1=248&p2=4399&p3=137&iv=0

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Agenda

OSTM coating issue
- Theoretical coating information from Hirose-san
  - AR reflection at 45 deg: 6% for s-pol, 3% for p-pol
  - HR transmission at 45 deg: 0% for s-pol, 13% for p-pol
    - measured to be T=3% for p-pol??? klog #8049
AS optical table layout JGW-T1909817 [Aritomi]
- In-vac layout basically done JGW-T1909618
  - A/I: Add OMC DC PD preamp to the layout to check the position. [Somiya]
- A/I: Tube between AS viewport and AS optical table, and a shield to block ambient light inside OMC chamber should be made [Michimura,Somiya]
  - Meeting with Akutsu-san on Feb 20: Tube first. Ask Sato-san at NAOJ ATC for the design.
  - Black tube design concept: JGW-T1909863 [Michimura]
- Also wind shield for AS table
2f and 3f RF PD JGW-G1909605 [Enomoto]
- Modification done klog #8144
High power compatibility of REFL table
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]
- Necessity of fast unlock of 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)

Minutes

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
  - REFL [Aritomi] (done) Output Tables Optics wiki
  - POP [done for green; Aritomi for IR]
    - Two RF PDs at POP table (POP and SPOP)
  - POS [done for green]
    - Obelisk with a hole and attachement designed JGW-D1909579
    - no IR (SPOS moved to AS table)
  - TRX/TRY [K. Nagano for both IR and green]
    - TRX designed and assembled JGW-T1808962
  - AS [Aritomi]
    - Two RF PDs at AS table (AS and SPOS)
  - 20 mm diameter optics post arrived.
OSTM coating issue
- ordered s-pol, AOI 3 deg, T<100ppm instead of p-pol, AOI 45deg, T=1%
- measured to be T=3% klog #8049
- under discussion in SEO
- OSTM somehow had to be thick, but Somiya forgot the reason
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.
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]
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
2f and 3f RF PD JGW-G1909605 [Enomoto]
- Gain bandwidth of opamp LMH6624 is 1.5GHz. We might want to lower the gain.
- A/I: Check with LTspice
  - Ref: http://nodus.ligo.caltech.edu:8080/PSL_Lab/2164
  - Ref: http://www.ti.com/product/LMH6624/toolssoftware
- Soldering of 2f and 3f RF PDs will be done by Enomoto-kun with help from AEL. We will ask AEL for tuning and further characterization.
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]
ALS report [Enomoto]
- Noise mainly comes from fiber noise and reduced to RMS of 13 Hz.
  - Fiber noise cancellation might be necessary.
    - Requires AOM and ~10% coupler.
  - Windshield for PSL table and POP table?
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.
RF modulation system
- Low noise VCO
  - Two Prototype Low Noise VCO for ALSX and Y assembled (JGW-D1808968), and noise of the one of them was measured. Meets the requirement.
  - We need three real ones for ALSX, ALSY and FSS
    - 110MHz for FSS? FSS AOM driver broken. Status?
  - For PLLX and PLLY, Keysight E8663D is used.
    - A/I: Need to develop a code to sweep the frequency.
- RF source
  - Harmonics Generator arrived
  - We currently have 6 Agilent N5181B, but we need 7 JGW-T1706762
    - PMC PDH (15MHz)
    - Refcav PDH (51.75MHz)
    - IMC PDH (13.78MHz)
    - seed for Harmonics Generator
    - ALSX PDH (33MHz) (NOTE that 33MHz for ALSX PDH, not 32MHz)
    - ALSY PDH (32MHz)
      - Not necessary until Yarm commissioning starts (mid-Nov?)
    - seed for ALS VCO (~70MHz)
      - Now uses Keysight 33611A-OCX klog #7019
  - RF amplifier for EOM requested to AEL JGW-T1809260
    - EOM RF Amplifier design JGW-T1809211 [Uehara,Michimura]
      - Attenuators should be taken out and connected outside during commissioning period for easy tuning. Attenuators will be put inside the chassis once values are fixed.
      - Input for voltage controlled attenuator fixed to be BNC
      - Make bigger mount panel for installing voltage controlled attenuator (and a low pass filter?) in the future
      - MIF/IOO already provided RF components and AEL will take care of the production
Common mode servo board CMSB wiki JGW-G1808547
- Summarized, requested to AEL JGW-T1809210
- We will make 20 boards, and 10 will be assembled as chassis
- We currently have 5 chassis and used for 1st MZI, IMC, CARM, PLL X, ALS PDHX
- Needs 4 chassis more soon: 2nd MZI, PLL Y, ALS PDHY, ALS COMM summing node
- 6 chassis for spare: MZI, IMC, CARM, PLL, PDH, summing node
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
General comments from Koji's Kamioka visit
- Many people assembling and installing things without looking at drawings
- Many works that can be done remote are done at Kamioka. Work at Kamioka is very expensive.
- Slow channels may be needed for monitoring things(PLC based? Beckhoff? Acromag?)
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
IMMT1 and IMMT2 transmission [Michimura, Takeda]
- IMMT2 transmission optics are too much squeezed
DC QPD holder [Michimura]
- beam height should be 4inch to use similar mount, with small modification of spacer (instead of 3inch in JGW-D1402607)
  - RF PD, RF QPD boxes are designed for 4inch beam height
- stages are not needed for ISC DC QPD
- design new ones; they can be very simple [-> Michimura?]
- calibration can be done in different ways
- put strain relief and anchors for cables to protect QPD board
Actuator noise modeling [Michimura,Miyamoto]
- Summarized in the paper JGW-P1707051
- Needs to implement frequency noise, but FSS modeling with ALS is complicated [student!]
- Discuss mirror vibration from heat link
  - Meeting on July 14 [Yamada, Miyamoto, Ushiba, Michimura]

See this page for other agendas.