Design and Development of Drum Capstan Exposure System by Multi-Beam Laser Scanning

Abstract

The unique recording system with the multi-frequency AOM (Acousto-Optic Modulator) was researched and developed. The multi-frequency AOM has useful multiple functions, for example, dividing one laser beam into plural beams, modulations, and corrections of beam positions along the sub-scan direction. Although the multi-frequency AOM produces significant benefits to the recording system as listed above, at the same time there are some drawbacks, such as heterodyne interference, 3rd order intermodulation, change of diffraction efficiency by number of diffracted beams, and image position shifts by the relative position between the image signals and the beat waves. These arise and need to be solved by optimizing the system design, fully considering the characteristics of the recording material. In this paper, we explain how to overcome the drawbacks and demonstrate that the system has achieved the fastest recording speed in the drum capstan exposure systems of imagesetters area, and also, the image quality suitable for commercial printing market.