| 摘要 |
<p>Illuminators (5, 6) are disposed oppositely on the opposite sides of a lens array (2). Assuming the effective depth of field of the lens array (2) is a, 90% power band width of the quantity of light distribution curve of the illuminators (5, 6) along the optical axis of the lens array (2) is not smaller than a for both illuminators (5, 6). Intersection (B) of the optical axis (Z2) of illumination light from the illuminator (5) and the optical axis (Z1) of the lens array (2) is located closer to the lens array (2) than a document side focal point (A) and the intersection (C) of the optical axis (Z3) of exiting light from the illuminator (6) and the optical axis (Z1) is located farther from the lens array (2) than the document side focal point (A). Distances between the intersections (B, C) and the document side focal point (A) are respectively not longer than a/2.</p> |
