INTERFEROMETRICS INC.

The Navy Prototype Optical Interferometer (NPOI) is a joint effort of the United States Naval Observatory (USNO), the Naval Research Laboratory, and the Lowell Observatory in Flagstaff, Arizona. The instrument serves as an imaging optical interferometer for NRL research personnel and as an astrometric interferometer for scientists at USNO. It is capable of imaging objects in the near-Earth space environment with a resolution of 0.2 milliarcseconds (1 nanoradian) at optical and infrared wavelengths from 450 to 850 nm. The NPOI has achieved unprecedented precision at optical wavelengths, with statistical and systematic errors below 10 milliarcseconds (below 50 nanoradians) for wide angle measurements and 1 milliarcsecond for narrow-angle measurements (object separations less than 1 degree). Closure phase measurement enables reconstruction (i.e. imaging) of the structures of celestial objects. The NPOI consists of six siderostats in a reconfigurable Y-shaped array with a maximum baseline of 437 meters. Light from a celestial object is sent through an evacuated feed beam system and mechanical delay lines to where it is combined interferometrically to yield visibility, amplitude, and phase data.  Routine NPOI astronomical observations began in 1996 and INTERFEROMETRICS continues to provide engineering and analysis services today. Among its recent tasks, it is being used to study the diameters of stars, the structure of fast rotating stars and gas disks around hot stars. Other uses of the NPOI involve the determination of orbital parameters of binaries, which can give important insight for stellar evolution models, and the precise measurement of the positions of bright stars. INTERFEROMETRICS engineers actively participated in the original NPOI design and construction.