With Shingo

In order to measure the laser power with a one power meter (S121C from ThorLabs), we put ND filters between the HWP and the PBS for LPD.
Then we got about 350mW before the PBS = point 1.

Result

With this condition, we measured point 1, 2, and 3.
The result mean that there is about 4% loss from point 1 to 2+3, which is consistent with the power loss of the PBS for LPD.
So we think unknown loss around this area should be about 1% at an accuracy of ~1%.

Details

Measured raw data is attached.
If we apply 1% correction based on the LPD value for the measured value of C=point 2:
A-(B+C*1.01) - power to LPD = 349.8 - (172.7+160.9*0.99) - 3 ~ 15mW
Because A = 349.8, this 15mW is about 4%.
According to this thesis, the PBS has 3% loss, which is almost consistent with our measurement this time.

We could not measure the point just after the PBS because of the limited space.