WHITE-LIGHT FIZEAU INTERFEROMETER

A white-light Fizeau interferometer is described. Commonly, white-ligh t fringes can be produced only by using a virtual wedge instrument suc h as a Michelson interferometer. By use of a series arrangement of a F abry-Perot interferometer in front of a two-beam Fizeau interferometer , white-light fringes can be produced. For white-light fringes to be o btained, the thickness of the air gap between the Fizeau plates has to be adjusted to the same thickness as the air gap between the Fabry-Pe rot plates (or in more general terms to a rational multiple of this va lue). The contrast of the two-beam type of Fizeau fringes depends on t he reflectivity of the Fabry-Perot plates. (C) 1997 Optical Society of America.