Patent ID: 7527376
Filing Date: 2009-05-05
Classification: G02C

Abstract:
1. A method for designing a spectacle lens mounted in a spectacle frame having a bend angle of 200 degrees or larger, comprising: adding astigmatic power on an object side refractive surface or an eyeball side refractive surface of the spectacle lens, for canceling aberration, caused by the bend angle of the spectacle frame, at a design reference point of the spectacle lens; setting prismatic power by tilting the refractive surface, which is on an object side or an eyeball side, of the spectacle lens for canceling prismatic power, caused by the bend angle of the spectacle frame, at the design reference point of the spectacle lens; extending a first reference meridian from the design reference point to the edge of the spectacle lens in a first direction which direction is a projected direction when a surface normal line at the design reference point of the spectacle lens having the bend angle of the spectacle frame is projected on a flat plane crossing a visual axis at a right angle; extending a second reference meridian from the design reference point to the edge of the spectacle lens in a second direction opposite to the first direction; extending a third reference meridian from the design reference point to the edge of the spectacle lens in a third direction, wherein the third reference meridian crosses the first reference meridian at the reference point at a right angle; extending a fourth reference meridian from the design reference point to the edge of the spectacle lens in a fourth direction opposite to the third direction; setting a plurality of reference meridians including at least the first reference meridian, the second reference meridian, the third reference meridian, and the fourth reference meridian; obtaining aspherical surface quantities optimizing optical performance on the respective reference meridians after the setting step; and obtaining aspherical surface quantities between the respective reference meridians by interpolation after the obtaining step.