There seems to be some discrepancy between power observed without sample(HWP) and with Sample(HWP). 

The power (normalised with main laser power) with sample / The power (normalised with main laser power) without HWP is shown in Fig 1 . It basically is the gain of the optical system which is transmitted power divided by the incident power.

Both the measurements were taken in a few days gap(~4-5 days). The normalization should have taken care of the laser power fluctuation. But, for some reason, the gain of the optics is more than 1. It could be arising from some inconsistent laser power increment or some very lossy optics before power meter to observe the main laser power. It could also be that the number lies within the uncertainity of the system.

The delta=det(J^+ J) and max intensity gain plot(of the HWP jones matrix) without considering the power factor in jones vector and without normalization is shown in Fig 2.