Holography set-up with two reference sources

The holographic interferometry bench presented in the paper is different from conventional set-ups in that it uses a second reference source. This source can be adjusted in position, and the phase of its radiation is continuously adjustable. This improvement increases the possibilities of applications of interferometry as it authorizes experiments impossible with the conventional interferometer or a current holography set-up. The operating mode calls upon the two techniques of reference hologram and of double exposure. Three examples of application on actual cases are presented, and illustrated by photographs.