A first manual overlap of the BAB and LO on the HD was performd Friday 19th,   by acting on the DL mirrors. 

With a more careful   tuning of the the LO beam power, by means of the HWO before the LO_PBS, at the end we measured a 96% HD  visibility (see attached picture).

It seems that the lab light turned on and the bench enclosure open prevent the fine equalization of the beams power since
this condition induces a variable bias on the photodiode used to measure.
Moreover it could be further improved by a fine LOtel tuning that is not possible at the present, being the lenses LO_L1 and LO_L2 without a micro-metric translator.

Useful could be to have the LO_HWP1 before LO_PBS motorized for a fine tuing of the power.