激光扫描成像中旋转多面体的分析计算

Analysis and Calculation of Rotating Polygonal Scanner in Laser Scanning Imaging System

对旋转多面体激光扫描成像系统作了理论描述及定量分析。为了保证扫描像点处于同一平面,将多面体置于成像物镜之前,当激光束以相对于光学系统光轴为2α角入射时,确定了入射光在多面体反射面上的位置、多面体中心转轴以及光学系统光轴三者之间的相对位置关系。推导了系统光学扫描角、扫描效率和入瞳漂移等参数的数学公式,分析了它们与入射光直径、入射角、多面体几何尺寸等因素之间的变化关系。结果表明,为减小系统的入瞳漂移和增大扫描效率,应以较小的入射角入射;进行系统设计时,若给定扫描角,扫描效率一般选择在0.4～0.7范围内较合理。

The quantitative analysis about a laser scanning imaging system for rotating polygon is theoretically described. The polygon scanner is located in front of the scan lens in order to guarantce the scanning image point in a flat field. It is important in system designing to determine the positional relationships between the incident beam at mirror, the rotation axis of the polygonal and the optical axis of the optical system when the angle of incident laser beam is 2a relative to the optical axis of the system, the calculation formulas of the scanning angle, scanning efficiency and the entrance pupil drift of the system are derived and the relationships between scanning angle, entrance pupil drift of system and many important factors （such as the width of the incident beam, incident angle and the geometrical size of the polygon, etc. ） are discussed in details. The results show, in order to increase the scanning efficiency of the system, the incident angle of laser beam should be small. And the range of scanning efficiency from 0. 4 to 0. 7 is more reasonable in the system designing.