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KAGRA MIR (Absorption)
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ManuelMarchio - 02:40, Tuesday 07 July 2015 (123)Get code to link to this report
LMA sample 15033

Last friday (3rd July) I cleaned both surfaces of LMA coated sample #15033 (abs=12.8ppm) as shown in the first picture using the first contact polymeric optics cleaner.

I measured the absorption of the sample along Z axis. I made scans of 10mm in order to see both surfaces. The sample thickness is 6mm.

I made a scan (blue line in the second figure) and then I flipped the sample in order to see also the other surface (black line) and I notices a strange peak, then I moved the sample 0.1mm along Y axis and I repeated the scan (red line). The black line shows an absorption that has a not usual pattern. I guess it is because of some scrach on the surface, because just 0.1mm apart it doesn't show.

This monday (6th July) I made again the measurement of sample and of flipped sample, (third picture). It shows a variation among the two surfaces of a factor of 2. Maybe it is just a fluctuation of the absorption value because flipping the sample we never go back to the same X,Y position.

Images attached to this report
123_20150706192918_rimg0002.jpg 123_20150706192937_plotlma15033friday.jpg 123_20150706194202_plotlma15033monday.jpg
Comments related to this report
ManuelMarchio - 12:36, Saturday 18 July 2015 (135)

I wanted to understand the big difference between the absorption peak in the configuration where the pump is entering in the sample by the absorbing surface and the other configuration where the pump is entering the sample by the not absorbing surface (flipped sample). So I made again a calibration and also a calibration with the flipped surface reference sample and I found a calibration factor R=17 1/W (flipped) and R=13 1/W (not flipped). For the not flipped sample I made a calibration history in this post and I found a mean calibration factor R=11 1/W with fluctuatoins of 10%. I don't understand why R changes so much. 

If we calculate the LMA15033 absorption with those R factors we get 22ppm for the flipped surface and 14ppm for the not flipped surface.