Marc, Matteo

Yesterday we tried to shift the ir beam using the pinhole at 2 positions.

However, after some back and forth between these positions, the power transmitted started to have a steep decrease...

Recentering the power-meter did not help.

We tried to remove the pbs and the waveplate between the 2 lenses as the beam started to get misaligned on these optics.

It did not change the power level.

Then I did several scan of the position of the imaging unit to check which is the good distance of the imaging unit with the new lens position. Before each measurement I tried to maximize both AC and DC.

I recorded both AC and DC and in figure 1 you can see the AC/DC in function of the imaging unit distance.

It seems that 74 mm corresponds to the maximum (previously it was 70 mm). Also, at this position there was a maximum of R~14 (goal is 18) maybe due to a better alignment compared to the other measurement?

I also preformed scan at each of these positions which still show umbalanced peaks.

Now I'll try to check again the beams propagation direction and the ir waist position as it might have changed again due to the removing of the pbs and waveplate...

If this does not work I'll try to remove the 2 lenses and start from scratch.