Imaging method and system with optimized extended depth of focus
An optical processor is presented for applying optical processing to a light field passing through a predetermined imaging lens unit. The optical processor comprises a pattern in the form of spaced apart regions of different optical properties. The pattern is configured to define a phase coder, and a dispersion profile coder. The phase coder affects profiles of Through Focus Modulation Transfer Function (TFMTF) for different wavelength components of the light field in accordance with a predetermined profile of an extended depth of focusing to be obtained by the imaging lens unit. The dispersion profile coder is configured in accordance with the imaging lens unit and the predetermined profile of the extended depth of focusing to provide a predetermined overlapping between said TFMTF profiles within said predetermined profile of the extended depth of focusing.
1. An imaging lens unit comprising: a lens having an optical power and a depth of focus, and first and second patterns carried by the lens, the first pattern being formed by a predetermined number of phase transitions being of substantially the same transparency and arranged with a low spatial frequency, so as to induce non-diffractive phase effect onto the light field, and a second pattern being diffractive to induce dispersion and which is configured to provide a predetermined optical power addition to the imaging lens, such that total optical power of the imaging lens unit corresponds to a desired optical power, dispersion and depth of focus properties of the imaging lens unit.
2. The imaging lens unit according to claim 1 , wherein said first pattern is configured for extending the depth of focus of the lens to provide a predetermined profile of the extended depth of focusing for different wavelengths; and said second pattern is configured to provide said desired optical power being substantially the same for different wavelengths.
3. The imaging lens unit according to claim 2 , wherein said first pattern is configured for affecting profiles of Through Focus Modulation Transfer Function (TFMTF) for different wavelength components of a light field being imaged by the lens in accordance with the predetermined profile of the extended depth of focusing to be obtained, and the second pattern is configured in accordance with the optical power of the lens and said predetermined profile of the extended depth of focusing to provide a predetermined overlapping between said TFMTF profiles within said predetermined profile of the extended depth of focusing.
4. The imaging lens unit according to claim 1 , wherein the first and second patterns are located at front and rear surfaces of the lens, with respect to light propagation direction towards the imaging lens.
5. The imaging lens unit according to claim 4 , wherein the first and second patterns are in the form of first and second surface reliefs on said front and rear surfaces of the lens.
6. The imaging lens unit according to claim 1 , wherein the first and second patterns are masks attached to the same or opposite sides of the lens.
7. The imaging lens unit according to claim 1 , wherein the first and second patterns are embedded in the lens.
8. The imaging lens unit according to claim 1 , wherein one of the first and second patterns is embedded in the lens, and other of said first and second patterns is located at either surface of the lens.
9. The imaging lens unit according to claim 1 , wherein the first and second patterns are incorporated in the lens, the first pattern being formed by spaced-apart regions of a material having a refractive index different from that of the lens, and the second diffractive pattern being a surface relief on one of the surfaces of the lens.
10. The imaging lens unit according to claim 1 , wherein the first and second patterns define together a combined diffractive pattern comprising a superposition of said first and second patterns.
11. The imaging lens unit according to claim 1 , wherein the imaging lens is an ophthalmic lens.
12. The imaging lens unit according to claim 11 , wherein said ophthalmic lens is configured as one of the following: a contact lens, an intraocular lens, or an intracorneal lens.