Multifocal diffractive ophthalmic lens with multifocal base surface

A multifocal diffractive ophthalmic lens comprising:

• a lens element having an anterior and a posterior surface;
• a diffractive multifocal zone disposed on one of the anterior and posterior surfaces, said diffractive multifocal zone including groove structure producing focal length fm of m-order diffraction for near focus;
• an opposite refractive zone disposed on another of the anterior and posterior surfaces, incident light passing consecutively through both zones;
• an intermediate focus producing part of said diffractive multifocal lens where the part is either at a base surface of said diffractive multifocal zone or opposite refractive zone, wherein the intermediate focus producing part is shaped to produce an intermediate focus of at least 0.5 D from far focus of said multifocal diffractive ophthalmic lens;
• and
• wherein a width of a diffractive groove of order “j” of said diffractive multifocal zone is increased at the intermediate focus producing part of said multifocal diffractive ophthalmic lens from a width of a groove of order “j” defined by a radial boundary position rj that results in a same focal length magnitude per a formula
• f
• m
• =
• r
• j
• 2
• jm
• ⁢
• ⁢
• λ
• for said near focus in order to produce phase function cycles by 2π period between boundaries of said increased width of the diffractive groove of order “j”, where “λ” is a design wavelength and “m” is an m-order diffraction.