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KAGRA MIR (Absorption)
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NaokiAritomi - 10:42, Thursday 15 April 2021 (2450)Get code to link to this report
Knife edge measurement in Y direction

[Aritomi, Abe, Marc]

We did knife edge measurement of IR and red beams with a knife at the edge of the 2'' holder towards the imaging unit. 

Fitting result is as follows:

IR : waist size = 40.8 um at z = 30.6 mm

red : waist size = 52.8 um at z = 39.8 mm

Note that Z in this plot is raw data and thickness of 2'' inch holder is not considered. The fitting for red doesn't match the data very well. 

Second figure is an example of knife edge measurement of red in Y direction at Z = 44 mm. There is a peak when the knife starts to cut the beam and this may underestimate the red beam radius. 

Images attached to this report
2450_20210419095903_20210409y.png 2450_20210419095913_z44.png
Comments related to this report
MarcEisenmann - 22:34, Monday 19 April 2021 (2459)

Also note that because we didn't take many points around ir waist position and with quite large step size (0.05mm), the ir beam parameters might also not be so reliable in this configuration.