The NPOI primarily produces space imagery and astrometry, the latter a major component required for the safe position and navigation of all manner of vehicles for the DoD.

[8] The NPOI is an astronomical interferometer laid out in a three-arm "Y" configuration, with each equally-spaced arm measuring 250 meters (820 ft) long.

Astrometric stations, used to measure the positions of celestial objects very accurately, are fixed units placed 21 meters (69 ft) apart, with one on each arm and one at the center.

[3] In 2009 NOFS began final plans for NPOI to incorporate four 1.8 m (71 in) aperture optical-infrared telescopes into the array, which were accepted by the Navy in 2010,[9][10] and assigned to the Naval Observatory Flagstaff Station.

Three telescopes are being prepared for near-immediate installation,[12][13] while the fourth is currently at Mount Stromlo Observatory in Australia and will be incorporated at some point in the future.

[11] The new telescopes will help with faint object imaging and improved absolute astrometry, due to their greater light-gathering abilities than the existing siderostats.

[11] NOFS operates and leads the science for the Navy Precision Optical Interferometer,[14][15] as noted, in collaboration with Lowell Observatory and the Naval Research Laboratory at Anderson Mesa.

Astrometry is understood by precisely measuring delay line additions while fringing, to match the light path differences from baseline ends.

To date NPOI has produced the highest resolution optical images of any astronomical instrument, though this may change when the CHARA array and Magdalena Ridge Observatory Interferometer begin optical-band operations.

[27] The first astronomical object imaged (resolved) by NPOI was Mizar, and since, a significant amount of astrometry, reference tie frame, rapid rotator star, and Be stellar disk study has been performed.

The current NPOI siderostat array remains the world's only long-baseline (437-meter) optical interferometer that can simultaneously co-phase six elements.