| 摘要 |
A laser exposure apparatus for printing forms to be imagewise exposed, said apparatus comprising: a laser light source (15) for producing a beam of light; a beam divider (17) for splitting said beam of light into a writing beam (24) and a reference beam; means (18) for modulating said writing beam; a rotating polygonal mirror (20) downstream of said modulating means and in the path of said writing beam; a housing (14) downstream of said polygonal mirror in the path of said writing beam and directly above said printing form, said housing comprising an exposure slit (23) in the path of said writing beam so as to allow imagewise exposure of said printing form; at least one additional exposure device (2, 2() comprising a light source which is disposed within said housing in the vicinity of said exposure slit, said additional exposure device radiating towards said printing form; and means for causing a delay between operation of said additional exposure device and imagewise exposure of said printing form by said writing beam, wherein each of the additional exposure devices comprises a linear LED arrangement (8) comprising at least two rows of modules of light-emitting diodes as a radiation source, said linear LED arrangement having a lengthwise extent sufficient to expose a printing form moving past the additional exposure device and underneath the latter over its full area at 25% to 35% of its luminosity, each of said additional exposure devices further comprising a light scattering plate (5) disposed on the underside of said housing, and covering said LED arrangement, and further comprising means for varying the luminosity of said LED arrangement over a power range of 0 to 100%.
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