  Aspera is a NASA Astrophysics Pioneers SmallSat mission designed to study
diffuse OVI emission from the warm-hot phase gas in the halos of nearby
galaxies. Its payload consists of two identical Rowland Circle-type long-slit
spectrographs, sharing a single MicroChannel plate detector. Each spectrograph
channel consists of an off-axis parabola primary mirror and a toroidal
diffraction grating optimized for the 1013-1057 Angstroms bandpass. Despite the
simple configuration, the optical alignment/integration process for Aspera is
challenging due to tight optical alignment tolerances, driven by the compact
form factor, and the contamination sensitivity of the Far-Ultraviolet optics
and detectors. In this paper, we discuss implementing a novel multi-phase
approach to meet these requirements using state-of-the-art optical metrology
tools. For coarsely positioning the optics we use a blue-laser 3D scanner while
the fine alignment is done with a Zygo interferometer and a custom
computer-generated hologram. The detector focus requires iterative in-vacuum
alignment using a Vacuum UV collimator. The alignment is done in a controlled
cleanroom facility at the University of Arizona.
