| 摘要 |
<p>An optical device for focusing a laser beam is disclosed. The device comprises a diffractive Fourier element (2) for separating an incident beam (6) into n beams (10-1, 10-5) travelling in n directions that are symmetrical relative to an optical axis (AA'), and a diffractive element (4) comprising n Fresnel lenses for refocusing the n beams onto the optical axis. The device is useful in lasers and laser cutting devices.</p> |
