| 摘要 |
<p>A rotating polygon mirror (4) deflects a continuous laser beam, applying the deflected beam to a beam-splitting mirror (8) through a focusing lens (6) which functions as an f theta lens. The beam is applied to the two reflective surfaces of the mirror (8) alternately. As a result, the mirror (8) splits the beam into two beams, which are applied to two beam-splitting mirrors (13) and (14), respectively. The mirrors (13, 14) split the input beams, each into two segment beams. The four segment beams are focused by lenses (15, 16), lenses (17, 18), lenses (19, 20), and lenses (21, 22), respectively, onto the surface of a web sheet (27), forming beam spots. The beam spots move in the same direction and at the same speed as the web sheet (27), thus scanning a limited surface regions of the sheet (27). As a result, rows of perforations, each being a truly circular hole, are formed in the web sheet (27). <IMAGE></p> |
