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KAGRA MIR (Absorption)
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MarcEisenmann - 20:14, Monday 10 May 2021 (2489)Get code to link to this report
KASI sample absorption measurement

The measurement performed during the golden week were using too low power (I_laser =3A ie P_laser~3.5W) that made it hard to really acquire signals.

The measurements have been restarted with higher power (I_laser=6A ie P_laser~8W?).

We'll have to check carefully the incident and transmitted power after the measurements.

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MarcEisenmann - 13:57, Thursday 13 May 2021 (2492)

Abe, Marc

Following the 3 maps measurements we performed again the bulk calibration where this time we moved the imagining unit by 0.32 mm in order to compensate the thickness difference between surface and bulk reference samples. We got the following result (also see last figure of this entry) :

AC_bulkref = 0.0731;
DC_bulkref = 4.164;
ACDC = 0.01755;
P_in = 29.5e-3;
P_t = 13.3e-3;
T_bulkref = P_t/P_in;
abs_bulkref = 1.04;
R_bulk = AC_bulkref/(DC_bulkref*sqrt(T_bulkref)*P_in*abs_bulkref) = 0.852 cm/W

Using this new calibration factor and using :

P_t = 6.25 W;
P_in = 7.322 W;

the absorption of this sample seems to be around 60 ppm/ cm for all 3 maps (see attached figures)

Today we will double check the bulk calibration as the change was quite larger than expected.

Images attached to this comment
2492_20210513065451_xy.jpg 2492_20210513065457_yz.jpg 2492_20210513065525_xz.jpg 2492_20210513065737_screenshotfrom20210513135724.png
MarcEisenmann - 16:12, Tuesday 18 May 2021 (2510)

It seems that the bulk calibration was overestimated. This is especially apparent when computing its transmission that was 45% instead of the expected 55%.

I performed again the bulk calibration and got :

AC_bulkref = 0.062;
DC_bulkref = 4.14;
P_in = 26.4e-3;
P_t = 13.1e-3;
T_bulkref = P_t/P_in
abs_bulkref = 1.04;
R_bulk = AC_bulkref/(DC_bulkref*sqrt(T_bulkref)*P_in*abs_bulkref) = 0.7743 W/cm

I used this new calibration to compute again the absorption map of the sample (see the 3 attached figures.

In the figure, the absorption is extracted from a fit using 2 normal distributions.

Here I also add the overall mean and standard deviation of each map (ie without any fittting) :

  XY YZ XZ
mean [ppm] 70 50 48
std [ppm] 8 35 37

 

Images attached to this comment
2510_20210518091159_xycorrected.jpg 2510_20210518091204_yzcorrected.jpg 2510_20210518091208_xzcorrected.jpg