components using a complex metrology array of lasers that connect main optical elements to each other and to bedrock. Many specialized lasers are also used to align the long train of optics. The current NPOI siderostat array remains the world's only long-baseline (437-meter) optical interferometer that can simultaneously co-phase six elements. NPOI is expected to grow significantly in capability with the pending addition of four 1.8-meter aperture IR/Optical telescopes into the current array. The enhanced array will also employ adaptive optics techniques. This layout and increased sparse aperture will permit significant improvements to the science capability, from a tenfold increase in measuring ever-fainter wide-angle astrometry targets, to improved positional determination for numerous binary and flare stars. When the 1.8m telescope addition are complete, NPOI also will undertake additional studies of dust and proto-planetary disks, and planetary systems and their formation. See also List of astronomical interferometers at visible and infrared wavelengths List of telescope types References External links United States Naval Observatory Flagstaff Station Additional USNOFS Information Lowell Observatory NPOI site Astrometry Optical telescopes Interferometric telescopes Military installations in Arizona United States Naval Observatory