Figure 3B: Example of a nearly-filled exit pupil with 278 elements, according to the "extreme Michelson mode". It can be obtained for example with 1.5m telescopes spaced 526m apart, along 9 concentric circles, thus forming a 10 km array. In its central region, the interference function differs little from an Airy pattern. The diffraction envelope, also an Airy pattern, is 18 times wider, thus providing on an extended object a direct image with 18x18 resolved elements.