NAOJ GW Elog Logbook 3.2
[Marc, Tsuzuki]
In the past years we made several measurements with ATC spectro-photometer which showed more or less good agreement with PCI measurement at 1064nm.
One suspect for discrepancy was the unpolarized light of the spectrophotometer.
We purchased a broadband polarizer and started measurement today.
Tsuzuki-san explained me how to operate the spectrophotometer and me made our first trial measurement with Shinkosha 50 30 3 sample.
We have to do calibration-> no sample -> s pol & sample -> p-pol & sample -> no sample measurement.
In current settings (220->2050nm, 0.1nm step and low scanning speed), it takes about 46mn per measurement.
One think we didn't considered for this 1st trial is the fact that initial calibration/background measurement are made with s-pol while later one are made with p-pol.
Last measurement is now on-going but at first glance it seems that s and p pol transmission is far more different than what I was expecting....
maybe misalignment of the sample or polarizer could be an issue..
The spectrophotometer will be kept on during the night.
Today I tried to measure the sample only with p-pol from calibration.
The input polarization is set by rotating the polarizer (spol = 358deg, ppol = 88deg).
It seems I made a mistake in saving the no sample measurement before the sample...
The strange features seen in sample transmission spectrum with ppol is also visible without sample.
More analysis to follow.
The spectrophotometer is off.