  The full LINC-NIRVANA instrument will be one of the most complex ground-based
astronomical systems ever built. It will consist of multiple subsystems,
including two multi-conjugate ground layer AO systems (MCAO) that drive the LBT
adaptive secondaries, two mid-high layer AO systems with their own Xynetics 349
actuator DM's , a fringe tracker, a beam combiner, and the NIR science camera.
In order to mitigate risk, we take a modular approach to instrument testing and
commissioning by decoupling these subsystems individually. The first subsystem
tested on-sky will be one of the ground-layer AO systems, part of a test-bed
known as the Pathfinder. The Pathfinder consists of a 12-star pyramid wavefront
sensor (PWFS) that drives one of the LBT's adaptive secondaries, a support
structure known as "The Foot," and the infrared test camera (IRTC), which is
used for acquisition and alignment. The 12 natural guide stars are acquired by
moveable arms called "star enlargers," each of which contains its own optical
path. The Pathfinder was shipped from MPIA in Heidelberg, Germany to the LBT
mountain lab on Mt. Graham, Arizona in February 2013. The system was unpacked,
assembled in the LBT clean room, and internally optically aligned. We present
the results of our system tests, including star enlarger alignment and system
alignment. We also present our immediate plans for on-sky closed loop tests on
the LBT scheduled for late Fall. Because plans for all ELTs call for ground
layer correction, the Pathfinder provides valuable preliminary information not
only for the full LINC-NIRVANA system, but also for future advanced MCAO
systems.
