| 摘要 |
An optical laser beam chopper for converting a continuous beam into a series of scanning impulses for use in perforating a moving web is disclosed. The system utilizes a coherent light source which produces a beam for use in perforating a thin paper web of the type used in producing cigarette filters. The beam passes through a rotary chopper, or shutter, system which incorporates a plurality of rotary discs each of which carries one or more annular rings divided into segments. Selected segments on each ring are formed of a reflective material to act as mirrors for the laser beam, while the remaining segments are in the form of apertures which allow the beam to pass through the disc. By properly aligning the various apertures and reflective surfaces, rotation of the discs will cause the beam to be cyclically directed along a variety of paths through the disc arrangement to periodically strike selected target areas on an adjacent target such as a web of paper, the repetitive cycling causing the beam to scan the various target areas. In the preferred form of the invention, the beam produces spaced perforations in the web, with motion of the paper web in a direction perpendicular to the direction of scan of the beam producing longitudinal rows of perforations, adjacent perforations being spaced in accordance with the speed of the web and the rate of scanning. The rotary disc segments thus serve to chop the laser beam into short impulses, each of which is directed to a target area corresponding to the angular position of the rotary disc. |
