An alignment strategy for the optics of LINC-NIRVANA

LINC-NIRVANA is an instrument to combine the light from both LBT primary mirrors in an imaging Fizeau interferometer. The goals in terms of resolution and field of view are quite ambitious, which leads to a complex instrument consisting of a bunch of subsystems. The layer oriented MCAO system alone is already quite complicated and to get everything working together properly is not a small challenge. As we are reaching the completion of LINC-NIRVANA's subsystems, it becomes more and more important to define a strategy to align all these various subsystems. The specific layout of LINC-NIRVANA imposes some restrictions and difficulties on the sequence and the method of this alignment. The main problem for example is that we have to get two perfectly symmetrical focal planes to be able to properly combine them interferometrically. This is the major step on which all further alignment is based on, since all the subsystems (collimator and camera optics, wavefront sensors, cold IR optics, etc.) rely on these focal planes as a reference. I will give a small introduction on the optics of the instrument and line out the resulting difficulties as well as the strategy that we want to apply in order to overcome these.