Abstract: A method and an apparatus for nondestructively detecting the orientation of anisotropic molecules in thin films and in molecular layers in general. The present invention is based on a single measurement of the non-polarized photoluminescence spectrum, in order to determine whether the molecules are orientated at right angles or parallel to the surface of the molecular layer, fabricated with any technique. The method is fast and noninvasive and can also allow to observe noninterferingly in real time during growth the orientation of the molecules in the film. The result of this real-time observation can be used to optimize the growth conditions of the film in order to achieve the intended molecular orientation.