Fig 1. - Picture of a micro-interferometer plate in its mechanical support (left). This plate contains 49 different interferometric configurations that have been drilled by laser lithography. The plate and its support are mounted at the front of a classical digital camera (EOS5D II) kept by Jean Surdej (right picture) when obtaining interferometric image of the Sun in April 2010 (Fg.2).

In the framework of Astrophysics lectures being taught by prof. Jean Surdej at the Liège University, students observed the Sun with the micro-interferometric device. The main goal was to measure the angular diameter of the Sun. This experiment is ideal to get familiar with the notion of fringe visibility and to learn the main steps of interferometric data reduction (i.e., background subtraction and model fitting). Examples of observations obtained on the Sun are shown in Fig.2 for the 2-hole and ELSA configurations. Generally, the students have measured the diameter ofthe Sun within a precision of 10%.