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Message ID: 2017     Entry time: Thu Feb 11 23:54:48 2016
Author: KojiN 
Type: Misc 
Category: PD QE 
Subject: Polarization measurement 

For measuring the polarization, the setup as shown in Fig. 1 was prepared.

The angle of the HWP #2 was 30 degree.

Rotating the angle of the HWP #3, I measured the laser power with a power meter and a PD.

And I fitted the measured data to the function, f(\theta) = a \sin^2(2(\theta-\phi)\pi/180)+b.

Here \theta is the angle of the HWP #3.

The result was shown in Fig. 2 and the paremeters were determined as

(with the power meter) a = 7.965 +/- 0.0005 mW, b = -0.002 +/- 0.003 mW, phi = -40.65 +/- 0.01,

(with the PD) a = 1373 +/- 3, b = -1 +/ 2, phi = 40.52 +/- 0.03. 

Accoding to this result, the S-pol. and the P-pol are obtained at 40.6 degree and 85.6 degree of the angle of the HWP #2, respectively.

And the calbration constant of the PD from voltage to power is determined roughly as 5.8*10^(-3) W/V. (Systematic errors have not yet been concerned.)

Fig. 1 Current setup.
Fig. 2 Measure data and fitted curves.


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