System and method for simultaneous 3D height measurements on multiple sides of an object

An interferometric method for determining a height profile of regions of the surface area of an object or of several objects, wherein the regions are substantially in different planes, is presented. The method comprises obtaining at least one image of the regions, by modifying an optical path of at least one portion of intensity coming from one of the regions, wherein each image comprises the portion of intensity and corresponds to an intensity pattern projected on the regions. An object phase associated to the regions is established using the obtained image(s) and a height profile of the regions is determined using the object phase and a reference phase. An optical assembly is used for directing along a common detection axis an intensity coming from said regions that would be otherwise out of sight.