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== OMC Blade Damping (2023/June/22) ==
 * Somiya-kun's Presentation
 *

Output Mode-cleaner

Meetings

Installation work

Reports

Requirement

Shot noise increase due to the signal reduction by the OMC and residual spatial higher order modes after the OMC should be less than 5%.

Optical Design (updated 19/8/11)

item

RoC

Beam Raidus

Misc

OMMT1

13.16m

4.46mm

Dia: 99.95mm, thick: 55.58(largest), wedge: 2.45deg (measured by Hirose-san 2018)

OMMT2

44.39m

2.68mm

Dia: 99.97mm, thick: 55.08(largest), wedge: 3.3deg (measured by Hirose-san 2018)

OSTM

flat

TBA

OMC1

flat

444um

OMC2

flat

444um(X)/447um(Y)

OMC3

1.80m

604um

OMC4

1.80m

604um

DCPD

--

592um

Space

Distance

AOI

SRM-OMMT1

5.63m

3.07deg

OMMT1-OMMT2

2.60m

3.07deg

OMMT2-OSTM

2.97m

90deg

OSTM-OBS1

0.30m

90deg

OBS1-OMC1

0.03m

0.078deg

OMC1-OMC2

0.357m

3.00deg

OMC2-OMC3

0.359m

3.00deg

OMC3-OMC4

0.357m

3.00deg

OMC4-OMC1

0.359m

3.00deg

Suspension Design

Total mass to be suspended

13kg

Number of suspensions

3

Blade spring size

220mm x 53mm

Radius of curvature

190mm

Distance from a blade end to a suspension wire

203.5mm

Blade material

MAS-1

Blade mass

4.3kg

Control Scheme

LSC

Dither frequency

1kHz (tentative)

Dither optics

OMC3 or OMC4

Signal extraction port

OMC trans DCPDs

ASC

Dither frequency

not yet decided

Dither optics

OSTM (tentative)

Signal extraction port

OMC trans DCPDs; on-board QPDs are used for the course alignment

OMC Venting and Repumping Procedure with HPL preparation with PLL (2023/Jan/30~Feb/3)

  • (Jan 30, Mon)
    • Before 9:00: FPMI realignment (Yokozawa-kun), Preparation for venting (Kimura-san, M.Takahashi-san), Turning on all FFUs in the OMC area.
    • Keep IMC lock using the present fiber laser. Stanby of R.Takahashi-san and Aso-kun for monitoring.
    • After informing the start of venting from Kimura-san to R. Takahashi-san, Kimura-san starts venting.
      • If OMMTs realignment with pico is necessary, It will be done.
    • After finishing venting, Kimura-san informs to R.Takahashi-san, Aso-kun, Miyakawa-kun and Miyoki.
    • Miyoki changes the PSL from OBS to Work mode at this time with IMC ASC? or around after all works are done on Jan 30?
      • IP2? HV drift monitoring.
      • Offload of IMC suspensions and IP1/2?
    • (Para)Just after the PSL mode change, Miyakawa-kun starts FB -> HPL changing and IMC control with HPL.

    • (Para)After closing the GV between SRM/SR2, Kimura-san starts opening the bellows at GV. So no laser to OMC area. Kimura-san starts the repair work. We would like to avoid removing the all bellows duct to reduce the risk to produce another leak on the healthy opposite side.
  • (Jan 31, Tue)
    • Kimura-san dose repair work and closes again. Also, after checking no problem happens in the vacuum level in SRM, the GV between SRM/SR2 is opened. Check the IR beam to and from OMC by ??.
    • Recover the operated FFU number in OMC as before this wrok.
    • After this work, R.Takahashi-san dose health check for OMC suspensions in this day or tomorrow morning
    • Miyakawa-kun PLL control adjustment with Izumi-kun. Sometimes, IMC unlock is expected?
      • The GR frequency will be kept, while the HPL IR frequency will be adjusted by changing the crystal temp.
  • (Feb 1, Wed)
    • Morning
      • Miyakawa-kun's HPL works.
    • Noontime
      • From 13:00?, Kimura-san informs R. Takahashi-san and Aso-kun about the start of pumping. The Kimura-san starts pumping gradually.
        • If OMMTs realignment with pico is necessary, It will be done.
  • (Feb 2, Thu)
    • Miyakawa-kun change the HPL to FB again? After this or earlier timing, the PSL room should be set to OBS mode again.(Or should we do in the week end holidays?)
    • Kimura-san/Yasui-san start the vacuum leak check. If no leak is verified, we will decide when we can open the GV, judging from the vacuum level reduction speed.
      • Opening GV might result in the realignment of the IF beam to OMC.
  • (Feb 3, Fri)
    • DGS maintenance day.

OMC Blade Damping (2023/June/22)

  • Somiya-kun's Presentation

KAGRA/Subgroups/IOO/OMC (last edited 2023-06-22 13:24:12 by miyoki)