NI TCS beam alignment on ITM

(Alessio, Viviana, P. Puppo. F. Frasconi)
Yesterday we performed the alignment of the TCS beam on the optics inside the NI tower.
With Franco, we re-installed mirror B and removed the protection from mirror A.
Then, with Franco and Paola, we looked for any diffusion of the
cross-hair on the first contact film of the ITM and nothing was
absolutely visible. We tried to put a diffusive screen hand-held, but
it was not possible to estimate the centering of the cross-hair. So,
following the original plan, a white screen was fixed on the reference
mass, 10mm from the mirror surface. The operation was done by Franco
and Paola and took around 15min to complete.
Then, we checked the position of the CO2 beam on mirror A and B by
looking at the position of the cross-hair laser on the mirrors. We
crosschecked by taking a picture of the CO2 ring on a screen placed on
mirror B with the handy thermal camera (see figure 1). In this way we
could check both if there is any clipping from mirror A and the
centering on mirror B. We aligned the cross-hair on the reference cross
drawn on the screen. We left the motors at half of their dynamics.