Document reading lens, document reading lens unit, document reader, and image forming apparatus

摘要

A lens for reading an image of a document includes three positive lenses, three negative lenses, a diaphragm, and at least one cemented lens that includes one of the positive lenses and one of the negative lenses cemented together. The document reading lens includes at least one aspheric surface. The lens adjacent to the diaphragm has the aspherical surface, and at least one cemented lens is arranged to be adjacent to the diaphragm.