d92cb313_u__Seoul___Patent_applications__Description
[Patent application number] 20100254026 [Published] 10-07-2010 [Description] 
OBJECT LENS - An object lens for an optical disk may include an aspherical lens surface, and an aspherical equation, which may be applied to form the aspherical lens surface may include two 2nd order function terms. Accordingly, a lens, which has a high numerical aperture (NA) and also has a small flexure on a lens surface or aberration, is provided.
Yu, Seoul - Patent applications