A three-dimensional optical memory device comprises an optical disc positioning system, two sources of radiation with wavelengths λ1 and λ2, a focusing system, an illumination system, focusing system positioning means, a spectrum splitter, an optical sensor, and a control unit. The radiation source with wavelength λ2 is an array of laser diodes, which optical axes are parallel and lie in the same plane. The illumination system comprises: a cylindrical lens positioned so that the generatrix of its cylindrical surface is parallel to the plane of the p-n junctions of the laser diodes; a focusing lens; and a stabilizing circuit comprising a beam splitter situated between the focusing lens and the cylindrical lens, a second optical sensor optically coupled to the focusing lens via the beam splitter, and a stabilizer coupled to the focusing lens, wherein the stabilizer and the second optical sensor are electrically connected to the control unit.