ANAMORPHIC CONVERTER AND IMAGE PROJECTION SYSTEM

摘要

An anamorphic converter includes, from a projected-surface side, a first group and a second group. The first group includes one or more lens elements and has a negative power at least in a main magnification direction. The second group includes one or more lens elements and has a positive power at least in the main magnification direction. Of optical surfaces, a last surface of the first group and a first surface of the second group: [1] have a power in both main magnification and sub-magnification directions; [2] are convex toward the projected-surface side in both main magnification and sub-magnification directions in a region having an area that is ¼ or more of an optical effective region area including a center portion of each of the last and first optical surfaces; and [3] at least one of the last and first optical surfaces is a free curved surface.