Fringe science: optical astronomical interferometry

Astronomical interferometry is a technique with which astronomers can combine information from two or more small telescopes to obtain the resolution of a large telescope. This technique has been applied extensively to radio frequency observations over the past 60 years, and during the past 30 years it has become viable at shorter wavelengths. In this paper I explain basic interferometric theory, the difficulties as they relate to visible and infrared wavelength observations, and some scientific payoffs made possible by interferometry