Fringe localization in wavefront division interferometers

When an amplitude division interferometer is illuminated by an extended incoherent source the fringes are localized. If the incoherent source is a periodic array of sources or if it continuous, there is a fundamental difference at the observation space and this is the appearance of several (more than one) localization surfaces. In the present paper it is stated that localized fringes can also be obtained in wavefront division interferometers provided the source is incoherent and periodic. As an example, the multiple localization planes in Fresnel's biprism are shown and experimental results are compared to the theoretical ones.