Optical lens system, optical scanning apparatus, and image forming apparatus

摘要

An optical lens system including a plurality of optical lenses which cooperate with each other to transmit a laser beam deflected in a main scanning direction to scan an object in the main scanning direction, and which include a first lens which is formed of a resin and has a tilt correction function, and at least one second lens which is remoter from the object than the first lens on an optical path. The first lens includes an effective lens portion which has a possibility that the laser beam is transmitted therethrough. The effective lens portion has an incidence surface to which the laser beam is incident in an optical-axis direction, and an outgoing surface from which the laser beam outgoes in the optical-axis direction, and at least one of the incidence surface and the outgoing surface is curved outward in a sub-scanning direction perpendicular to the main scanning direction and the optical-axis direction. The first lens further includes at least one first ineffective lens portion which has no possibility that the laser beam is transmitted therethrough, and which is located adjacent the effective lens portion in the sub-scanning direction. In a cross section of the first lens taken along a plane perpendicular to the main scanning direction, the at least one first ineffective lens portion does not project outward from the outward curved surface of the effective lens portion in the optical-axis direction.