Abstract: The method comprises producing a coherent light beam in which the distribution of luminous intensity is representative of the object under study, forming an image representing the complex Fourier spectrum of the function describing said distribution of luminous intensity, and producing first data in response to the luminous intensity in a part of said image and second data in response to the relative phase of the light waves producing said image. The first data are representative of the object and of its orientation and the second data are representative of the position of the object.