A beam shaper intended for use in connection with a quasi-monochromatic light source and which is fabricated from a substantially transparent material as a transmission element guiding the propagation of light for rounding, making elliptical, collimating, diverging, converging and/or for the like application of a light beam/beams. The beam shaper has its transmission element guiding the light beam/beams provided with a structure which at least partially consists of binary, surface relief type of diffractive patterns, having local granting periods thereof optimized with respect to longitudinal and transverse directions, as well as with respect to an optical axis, essentially in accordance with the Bragg diffraction geaometry for providing a maximum diffraction efficiency.