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KAGRA AOS (General)
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SimonZeidler - 17:01, Friday 13 March 2015 (39)Get code to link to this report
Backscatterometer
There is maybe a problem with the ghost beams coming from the BS and hitting the Iris in front of the sample.
I am afraid that this will produce some additional scattering light which superpositions the backscatter-signal and disturb the measurements especially for wide angles.

Torii-san and I tried to set an obliqued ND filter in front of the Iris to remove the ghost beam hitting the surface of the Iris.
The first results seem to support my fears.
Estimated influence on photocurrent: 0.1 - 0.2 nA
Comments related to this report
TomotadaAkutsu - 18:04, Friday 13 March 2015 (42)
Yes, Simon would be right. Please do the dump of ghost beams in that way.