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Michelson's Stellar Interferometer

Masud Mansuripur

The essential idea behind the stellar interferometer is that of a double-slit interferometer, shown in Figure 1. This type of instrument dates back to 1868 when Fizeau1 proposed using it to measure the diameters of the fixed stars. Some modern textbooks2 describe the stellar interferometer in the language of coherence theory, which tends to obscure its fundamental simplicity. This article presents the original concept in its simplest form, while providing an historical perspective.