Patent ID: 7350918
Filing Date: 2008-04-01
Classification: A61B,A61F

Abstract:
1. A method for determining the shape of a lens having equal conic surfaces to minimize spherical aberration, comprising: (a) performing an optimization search to minimize an error function over a conic constant K to calculate the lens parameters apical radius R, conic constant K, and center thickness CT for a selected lens power, optical zone, edge thickness and material index of refraction; (b) performing a calculation of paraxial focal point distance; (c) performing an optical ray tracing calculation for a selected marginal ray height using the lens parameters apical radius R, conic constant K, center thickness CT and index of refraction to calculate a marginal ray intersection point; (d) calculating the signed distance between the marginal ray intersection point and the paraxial focal point distance to determine the error function used in the optimization search; and (e) performing iterative calculations to determine the apical radius R and center thickness CT used in the error function of step (a) for a current value of K, lens power, optical zone, edge thickness, and material index of refraction until values of apical radius R and center thickness CT converge so as to provide the shape to be used for forming the lens.