##entry of last Friday lost in the drafts##

We continued the alignment of the green beam towards the North/West fiber couplers. We were able to follow the path of the counter-propagated green laser and finally reach both fiber couplers.

After several attempts, we successfully injected the reference beam into one of the two fibers (the one corresponding to the North Arm) with ~30% coupling efficiency. Unfortunately, on the other fiber we could only achieve ~0.5% coupling (without further touching the alignment). This suggests that the axes of the beams coming from the two arms are not perfectly superimposed.

However, a fine adjustment will be carried out on Monday using the two mirrors equipped with picomotors (see Fig. 1).

Side note: 

• We temporary connected the picomotors of the two ALS mirrors (used to align the reference beam) to the "picoAppEIB" server. For the time being,  the first mirorr (bottom circle on fig. 1) is controlled using "FAR_M1_{Tx, Ty}" DoF, the second one (top circle on fig. 1) using "M8_{Tx,Ty}". 
• We added the control of the flip mirror for the reference green beam (violet circle on fig. 1). It is now connected to the TTL_inj server in the flip mirror TCS rack of the piscina, on the channel 5 (green cable in fig. 2).
• In addition, we also prepared two additional flip mirror cables (yellow and blu ones),  which may be used in the future on the main beam path.