Patent ID: 6839174
Filing Date: 2005-01-04
Classification: G02B

Abstract:
1. A relief type diffraction optical element having a non-even width grating pattern formed in one of two major surfaces of a substrate, wherein said grating pattern comprises: a first zone group including at least a first zone, said first zone having an optical axis of the optical element passing therethrough and a cross sectional configuration which, at a cross section cut along the optical axis, when viewed in one direction from the optical axis toward a periphery of said substrate in a direction normal to the optical axis, comprises a plurality of portions located on one side of the optical axis when viewed in said one direction, each having different inclination angles with respect to a plane perpendicular to the optical axis of the optical element, said first zone group containing a maximum width or pitch zone, said plurality of portions being continuous with one another and none of said plurality of portions is parallel to the optical axis; and a second zone group which is disposed at a periphery of said first zone group and includes a plurality of zones, each of said plurality of zones having a cross sectional configuration which, at said cross section cut along the optical axis, when viewed in said one direction from the optical axis toward said periphery of said substrate in said direction normal to the optical axis, has an inclination angle, having a constant absolute value, with respect to said plane perpendicular to the optical axis of the optical element.