Abstract: The present invention relates to an apparatus and a method for determining anisotropies affecting the polarization properties of light in microscopically small objects using optical microscopy. In particular, the invention relates to an apparatus comprising an optical path extending between a light source and an optical sensor, wherein the object, or specimen, is placed in this optical path. The optical path also includes an element for polarization analysis and at least one element adjustable by a controller, the at least one adjustable element causing a rotation of the polarization properties of light passing through said element, wherein the rotation is controllable with respect to its angle. A controller module of the apparatus applies at least three different rotation angles and acquires an image of the object for each of the at least three different rotation angles using the optical sensor.