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KAGRA MIR (Absorption)
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MarcEisenmann - 10:28, Wednesday 28 April 2021 (2476)Get code to link to this report
3d absorption map of 1cm thick SHINKOSHA sample

Abe, Marc, Matteo

Following the measurement of the absorption map at z=51.4 mm, we performed 2 others map in the XZ and YZ planes.

They correspond respectively to figure 1 and 2.

An important point to notice is that there seems to be a point absorber on the surface that distorts the absorption scale (up to 4000 ).

We decided to turn off the ir laser just in case.

Anyway looking at the histogram, it seems that the nominal absorption is around 400 ppm/cm (more precise analysis to come).

In figure 3 you can see a combination of the 3 maps where the colorbar scale has been limited to the maximum of the circular map (ie 1500 ppm/cm).

Images attached to this report
2476_20210428032407_202104271cmshinkoshaxz.jpg 2476_20210428032417_202104271cmshinkoshayz.jpg 2476_20210428032425_202104271cmshinkoshaoverview.jpg
Comments related to this report
MarcEisenmann - 17:34, Wednesday 28 April 2021 (2478)

Marc, Matteo, Yuhang

We used the green light to check possible dust on the mirror and took a picture after already using the air dust once.

The mirror is really dirty...

We then used again the air dust and could remove most of the large dust particles but not the smallest one (not visible on picture so no 'after picture').

We can still see the ethanol/acetone trace at the mirror edge so the mirror got dirty either during shipping or during the few weeks it stayed inside the clean room without cover.

We will clean it with first contact after the golden week.

SimonZeidler - 19:12, Sunday 02 May 2021 (2481)

Nice results!

It seems that Shinkosha still has its main feature: the prominent spider-web absorption.

But the absorption is really high this time.

MarcEisenmann - 14:52, Monday 10 May 2021 (2487)

Thank you.

I have updated the absorption value using the bulk calibration measured just after removing this sample (see elog 2480) and the corrected absorption is 302 +/- 108 ppm.

MarcEisenmann - 11:05, Thursday 13 May 2021 (2491)

Abe, Marc

 

We modified the analysis to better estimate the mean and standard-deviation of absorption measurements.

The corrected results are attached to this entry.

Today I will remove the first contact that we applied on this sample and cross-checked if it affected the absorption measurement.

SimonZeidler - 16:22, Friday 14 May 2021 (2495)

I have some questions.

What is the meaning of the fit in the histograms? Do you have a reason to fit with specific distributions/densities or do you want to find a systematic pattern?

MarcEisenmann - 10:27, Monday 17 May 2021 (2504)

The absorption distribution is fitted with 2 normal distributions.

I thought it could be useful for the case of XZ and YZ maps (where there are measurement points outside the sample) because it allows to remove the effects of absorption outside the sample and point defects/dust on the surface.

But I agree that it might not be the most suitable distribution, especially for the shinkosha samples...