A phase sensitive interferometer technique for the measurement of the Fourier transforms of spatial brightness distributions of small angular extent

A method is described whereby the amplitude and phase of the complex Fourier transform of a spatial brightness distribution of small angular extent may be uniquely determined from a series of measurements with a triple interferometer system. Absolute measurement of the amplitude function is available, whilst measurements of phase are relative to a datum obtained at short aerial spacings. A practical radio frequency interferometer incorporating the principle is described and fts operation is discussed.