| 摘要 |
A laser exposure apparatus utilizing a laser, beam divider, modulator, beam expander, beam combiner, polygonal mirror and also a scanner lens, path-folding mirror and a reference mask. The laser beam is divided in the beam divider into a writing beam and a reference beam, both of which are brought together by means of two path-folding mirrors and a beam combiner. The writing beam is then guided through an exposure slit onto a printing form by a path-folding mirror. One additional exposure device is disposed upstream and/or downstream of the exposure slot, and in the direction of conveyance of the printing form. Only one of the additional exposure devices is switched on during operation, so that either a preexposure or an afterexposure is accomplished in addition to the laser main exposure of the printing form.
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