  The widefield diamond nitrogen-vacancy (NV) microscope is a powerful
instrument for imaging magnetic fields. However, a key limitation impeding its
wider adoption is its complex operation, in part due to the difficulty of
precisely interfacing the sensor and sample to achieve optimum spatial
resolution. Here we demonstrate a solution to this interfacing problem that is
both practical and reliably minimizes NV-sample standoff. We built a compact
widefield NV microscope which incorporates an integrated widefield diamond
probe with full position and angular control, and developed a systematic
alignment procedure based on optical interference fringes. Using this platform,
we imaged an ultrathin (1 nm) magnetic film test sample, and conducted a
detailed study of the spatial resolution. We reproducibly achieved an estimated
NV-sample standoff (and hence spatial resolution) of at most $\sim2~\mu$m
across a $\sim0.5$ mm field of view. Guided by these results, we suggest future
improvements for approaching the optical diffraction limit. This work is a step
towards realizing a widefield NV microscope suitable for routine
high-throughput mapping of magnetic fields.
