An optical system has a light source of an optical beam, and a wavefront distortion generator that introduces a known wavefront distortion into at least one wavelength component of the optical beam prior to the formation of an intermediate image. A focusing device receives the optical beam, produces the intermediate image of the optical beam, and outputs the optical beam. A wavefront distortion corrector, after the formation of the intermediate image, introduces a wavefront distortion correction into each component of the optical beam into which the known wavefront distortion was introduced by the wavefront distortion generator. The wavefront distortion correction is the reverse of the known wavefront distortion introduced into the optical beam by the wavefront distortion generator.