| 摘要 |
<p>A polygon mirror has a plurality of elliptically-curved convex mirror surfaces (1a to 1f) functioning as light reflection surfaces, each having substantially the same shape as the maximum curvature portion of an ellipse (2) which has long axis b and short axis c. The convex mirror surfaces (1a to 1f) are uniformly arranged on the circumference of an inscribed circle whose center (O) is set on the long axis b, whose radius is Rm, and which is in contact with the maximum curvature portion of the ellipse (2). The polygon mirror (1) reflects an incident light beam while being rotated, and scans the incident light beam in the range of effective scanning length Lo on a preset scanning plane (SP) which is set at incident light beam travelling distance R from the center (O) of the inscribed circle of the polygon mirror (1).</p> |
