LENS WITH LOW BIREFRINGENCE, METHOD OF FABRICATING THE LENS, AND LIGHT SCANNING UNIT INCLUDING THE LENS

摘要

There are provided a lens, a method of fabricating the lens, and a light scanning unit. The lens includes a lens portion having an effective optical surface, and a gate-side flange portion between the lens portion and a gate-side end of the lens. If the lens is disposed between two polarizers configured to polarize light linearly in perpendicular directions and is illuminated in an optical axis direction, interference fringes are generated on the lens, and peripheral interference fringes of the interference fringes extend continuously from the gate-side end and are longer than the gate-side flange portion.

主权项

1. A method of fabricating a lens through an injection molding process, the method comprising:
filling a melted resin into a cavity of an injection mold through a gate; performing a first packing operation by continuously injecting the resin into the cavity so as to compensate for shrinkage of the resin cooled in the cavity after the filling the resin; after a surface of the resin is solidified in the cavity, performing a second packing operation by reducing a holding pressure so as to allow a part of the resin that is not solidified to backflow from the cavity to the gate; and before the gate is sealed, performing a third packing operation by re-injecting the resin into the cavity so as to compensate for shrinkage of the resin cooled in the cavity.