Abstract: Random jitter of the rotational axis in scanners produces scan-line tracking errors that are unacceptable in the laser typesetting and printing industry. The design of the Butterfly scanning device nullifies scan-line cross-scan tracking errors stemming, in part, from bearing wobble. Terms and expressions associated with types of line scanning systems and reflective rotary scanning devices are defined. The essential features of an Axe-Blade scanner, a two- facet scanning device, and the principles of a Butterfly scanner, a two piece, four-facet scanning device, are described. The symmetry of the Butterfly scanner simplifies its design and construction, its alignment and dynamic balancing; and leads to a compact unit. The design uses commercially available bearings, and achieves scanned beam accuracies in the arcsecond and the subarcsecond ranges that, in general, require gas bearings.!
展开▼
