NAOJ GW Elog Logbook 3.2
This entry reports the birefringence measurement of TAMA #1 with 1.5cm radius, 0.25 mm step size, 0.5s wait time and 0.488mW input power.
Due to time constraints only 3 measurements were possible.
Note that the AC and DC was realigned before input polarization calibration and with sample and that here 0 deg polarization angle corresponds to s polarization.
The analysis code was checked using the Shinkosha7 data and produced identical results.
The main result is that polarization, theta and delta_n are quite uniform but the main variation corresponds also to the maximum absorption (see entries 2723 or 2672) while the triangular patterns does not seem to affect significantly these parameters.
That looks very good, indeed!
What you can do in addition is to check for the second (negative) solution according to theory, as I reported last meeting.
An important point is also to be very precise with all input parameters. For example, it isn't enough to set the thickness to just 6cm or so but to take into account the refraction due to the inclination and the hence extended beam path.