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MIF (ASC)

hirose.chiaki - 21:57 Monday 03 October 2022 (22310)

Measurement of power on TMSX IR

[Terri, Keiko, Chiaki]

The calculated power entering the TSM table is 677uW.

The power could not be measured after the periscope as the beam was too large.

We measured 538uW after the first lens and 525uW after the second lens on the table, so estimate ~550uW entering the table.

Our calculation is an estimate and there may be additional loss in the arm or on transmission through the mirror so the power seems reasonable and therefore we cannot conclude any losses from birefringence.（Written by Terri）

We also repositioned the optics after lens2 for the optical axis of future QPDs.

(TMSX_20221003.png : blue power->measurement power, blue number: number of opitical tabel hole : ../../users/Commissioning/data/ASC/2022/TMSX/BeamProfile/20221003/KAGRA_TMS_Xarm.sng)

This figure shows the PD signal of TRANS IR before and after placing PD. (TMSX_IR_power_before_after_placing.png)

Images attached to this report

22310_1664801407_TMSX_IR_power_before_after_placing.png

Comments to this report:

takafumi.ushiba - 9:05 Tuesday 04 October 2022 (22322)

Hi Hirose-san,

I cannot follow how to calculate the deal value (677 uW).
Could you explain sligtly more detail of the calculation for the future references (how much injection power, what kind of assumption is used, and so on)?

hirose.chiaki - 11:34 Tuesday 04 October 2022 (22324)

We calculated the following setup.

Xarm end mirror Transmission ratio:5e-6
Xarm end mirror Transmission ratio:0.004
Xarm end and front mirror Loss:45ppm
imput power(trans power of IMC):3W
Calculation Result--->>> finesse : 1531.28, Trans power : 714uW

However, since the results were different from the measurement results,
we changed the mirror loss and also calculated the results.

Xarm mirror Loss:150ppm --->>> finesse : 1456.58 : Trans power : 646uW

Calculation Process: ../../users/Commissioning/data/ASC/2022/TMSX/BeamProfile/20221003/calculation_trans_power.py

Non-image files attached to this comment

calculation_trans_power.txt

Terri Pearce - 18:41 Tuesday 04 October 2022 (22339)

The measured power at different points on the table is summarised in the power budget table below.

Place	Power [uW]
After RLNS1	538
After RLNS2	529
Before RBS	295
After RST5	119
After RBS3	55
Before RPD1	58
Before RST1	Estimate 550

keiko.kokeyama - 19:55 Tuesday 04 October 2022 (22340)

These powers are when the X arm (only) was locked with input power (at BS-ITMX) of 0.15W (IMC TRANS 3W, PRM misaligned).

The optical layout at TMSX in-air table can be found
https://gwdoc.icrr.u-tokyo.ac.jp/DocDB/0089/T1808962/009/181012_KAGRA_TMS_GPT_ver4.png
DC QPDs (RQPD1 and 2) are not yet placed at the final positions.

hirose.chiaki - 23:48 Wednesday 05 October 2022 (22365)

I checked each power when TMSX measurement.
This fugure(Each_power_when_measurement_TMSXpower.png) is shown laser power source(green), PMC trans power(red), PSL room trans power(blue), IMC trans power(orange), TMSX power(purple) and REFL port power(brown).

Rough averages of these powers are as follows．
laser power source(green),6.18[W]
PMC trans power(red), 6.42[W]
PSL room trans power(blue), 4.22[W]
IMC trans power(orange),3.85[W]
REFL port power(brown), 0.13[mW]

[With Kenta]

We calculated the power on the REFL port.
REFL port POWER(Loss of mirror is 45ppm) : 0.34 mW
REFL port POWER(Loss of mirror is 150ppm) : 0.27 mW
We didn't know the angle of the HWP or the transmittance of the TFP on the REFL port, so we couldn't be detail.
It was good because both orders were close.

Images attached to this comment

22365_1664972039_Each_power_when_measurement_TMSXpower.png

Non-image files attached to this comment

calculation_trans_power.txt