| 摘要 |
Several optical heads are mounted on a common carriage adapted to scan a photosensitive printing plate. Each head is equipped with a laser source, a modulator and projection optics and can project a segment containing a plurality of pixels. The optical track of beams in each head is folded several times in such a way as to reduce the width of the head as well as its height. When the carriage moves from one edge of the plate to the other edge a swath of pixels is projected. Each head includes means to adjust the width, location, orientation and intensity of the segment it generates. Each head is accurately positioned on the carriage so that at least two abutting swaths are projected during each sweep of the carriage to produce a wider swath.
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