Multi-ring lens, systems and methods for extended depth of focus
Systems and methods for providing enhanced image quality across a wide and extended range of foci encompass vision treatment techniques and ophthalmic lenses such as contact lenses and intraocular lenses (IOLs). Exemplary IOL optics can include an aspheric refractive profile imposed on a first or second lens surface, and a diffractive profile imposed on a first or second lens surface. The aspheric refractive profile can focus light toward a far focus. The diffractive profile can include a central zone that distributes a first percentage of light toward a far focus and a second percentage of light toward an intermediate focus. The diffractive profile can also include a peripheral zone, surrounding the central zone, which distributes a third percentage of light toward the far focus and a fourth percentage of light toward the intermediate focus.
1. An ophthalmic lens, comprising:
an aspheric refractive profile imposed on a surface of the lens; and
a diffractive profile imposed on a surface of the lens and characterized by a wavelength;
wherein the diffractive profile comprises a plurality of echelettes having respective step heights that are greater than the wavelength;
wherein the diffractive profile directs one diffractive order to a far focus of the lens, and another, higher diffractive order to an intermediate focus of the lens; and
wherein the step heights of the plurality of echelettes are within a range between four and eight microns.
2. The lens of claim 1 , in which the diffractive profile includes a central zone that distributes light toward the far focus and the intermediate focus, and a peripheral zone, surrounding the central zone, that distributes light toward the far focus and the intermediate focus.
3. The lens of claim 2 , in which the central zone includes one or more echelettes, and the peripheral zone includes a plurality of echelettes, the step height of each peripheral zone echelette being less than the step height of each central zone echelette.
4. The lens of claim 3 , in which the central zone includes two or more echelettes.
5. The lens of claim 2 , in which the central zone includes at least one echelette having an optical path difference of 1.5 wavelengths of the diffractive profile, and the peripheral zone includes at least one echelette having an optical path difference of 1.366 wavelengths.
6. An ophthalmic lens, comprising:
an aspheric refractive profile imposed on a surface of the lens; and
a diffractive profile imposed on a surface of the lens and comprising a plurality of echelettes having respective step heights;
wherein the diffractive profile directs first order diffraction to a far focus of the lens, and second order diffraction to an intermediate focus of the lens; and
wherein the step heights of the plurality of echelettes are within a range between four and eight microns.
7. The lens of claim 6 , wherein the diffractive profile is characterized by a wavelength and the step heights are greater than the wavelength.
8. The lens of claim 7 , in which the diffractive profile operates to distribute incident or incoming light substantially or predominately to a first and second diffractive orders.
9. The lens of claim 7 , in which the diffractive profile includes a central zone that distributes light toward the far focus and the intermediate focus, and a peripheral zone, surrounding the central zone, that distributes light toward the far focus and the intermediate focus.
10. The lens of claim 9 , in which the central zone includes one or more echelettes, and the peripheral zone includes a plurality of echelettes, the step height of each peripheral zone echelette being less than the step height of each central zone echelette.
11. The lens of claim 10 , in which the central zone includes two or more echelettes.
12. The lens of claim 9 , in which the central zone includes at least one echelette having an optical path difference of 1.5 wavelengths of the diffractive profile, and the peripheral zone includes at least one echelette having an optical path difference of 1.366 wavelengths.
13. An intra-ocular lens having an anterior face and a posterior face and a diffractive profile imposed on the anterior or posterior face, wherein the profile has an inner portion consisting of a central or inner echelette and an outer portion comprising a number of echelettes, wherein the diffractive profile directs first order diffraction to a far focus of the lens, and second order diffraction to an intermediate focus of the lens, and wherein the number of echelettes of the outer portion have step heights within a range between four and eight microns.