Participants: Yuhang, Eleonora

We have characterized the IR beam from the main laser transmitted by the first BS. We have measured the beam starting from the 48th hole (which is about 6 cm after the lens with f = 500 mm).

The beam is quite collimated: it has a waist of 0.67 mm ad a distance z = +2.9 m from the 48th hole. In the region around the 50th hole it has a diamiter of about  3 mm.

We plan to take a pickoff of the beam in this region and use it for the PLL. We will inject it into a fiber through a collimator. Accoring to the collimator characterization reported here, we need to prepare a collimated beam with a diameter of about 2 mm.

A possible solution for the telescope is to use two lenses with f = 75 mm and f = 50 respectively,  placed at a distance of about 12.3 cm from each other.  See in the attachement the jammt simulation.