Optical lens for correcting astigmatism

• US 5,016,977 A
• Filed: 02/05/1990
• Issued: 05/21/1991
• Est. Priority Date: 02/06/1989
• Status: Expired due to Fees

• Current Assignee: Essilor International SA (EssilorLuxottica SA)
• Original Assignee: Essilor International SA (EssilorLuxottica SA)
• Inventors: Chavel, Pierre, Taboury, Jean, Baude, Dominique, Joyeux, Denis
• Primary Examiner(s): Sugarman, Scott J.
• Application Number:
  US07/475,159
• Time in Patent Office: 470 Days
• Field of Search: 351/160 R, 351/160 H, 351/161, 351/162, 351/176, 350/162.17, 350/162.20, 350/162.21, 350/162.22, 350/162.23, 350/162.24, 623/6
• US Class Current: 359/570
• CPC Class Codes: A61F 2/14 Eye parts, e.g. lenses, corneal implants; Implanting instruments specially adapted therefor; Artificial eyes
• CPC Class Codes: A61F 2/145 Corneal inlays, onlays, or lenses for refractive correction
• CPC Class Codes: A61F 2/164 Aspheric lenses
• CPC Class Codes: A61F 2/1654 Diffractive lenses
• CPC Class Codes: G02B 27/0037 with diffracting elements G02B27/0056 takes precedence; holographic optical elements G02B5/32; zone systems G02B5/1876
• CPC Class Codes: G02B 27/4216 correcting geometrical aberrations
• CPC Class Codes: G02B 5/1876 Diffractive Fresnel lenses; Zone plates; Kinoforms G02B5/1842, G02B5/1847 take precedence; optical systems having diffractive correction means G02B27/0037; Fresnel lenses operating by refraction G02B3/08
• CPC Class Codes: G02B 5/188 Plurality of such optical elements formed in or on a supporting substrate
• CPC Class Codes: G02C 2202/20 Diffractive and Fresnel lenses or lens portions
• CPC Class Codes: G02C 7/04 Contact lenses for the eyes disinfection or sterilisation of contact lenses A61L12/00
• CPC Class Codes: G02C 7/042 Simultaneous type
• CPC Class Codes: G02C 7/045 Sectorial configuration

Abstract

The present invention relates to an optical lens for correcting astigmatism. It includes diffractive components whose outlines are delimited by conic section curves having non-degenerate centers. More precisely, in accordance with the invention, the lens includes adjacent diffractive components having hyperbolic or elliptical outlines with a periodicity in r² in two mutually orthogonal directions x and y intersecting on the axis of the lens and coinciding with the main axes of the hyperbolas or of the ellipses, which are determined respectively by the equations: Δr_x² =2λ|f_x |; and Δr_y² =2λ|f_y |; in which: Δr_x² represents the periodicity in r² along the x direction; Δr_y² represents the periodicity in r² along the y direction; λ represents the mean utilization wavelength; f_x represents the desired focal length in the X direction; and f_y represents the desired focal length in the Y direction.

Claims

1. A lens for correcting astigmatism, including adjacent hyperbolic- or elliptical-outline diffractive components whose periodicity in two mutually orthogonal X and Y directions intersecting at the axis of the lens and coinciding with the main axes of the hyperbolas or the ellipses are respectively determined by the equations:

space="preserve" listing-type="equation">Δ

r.sub.x.sup.2 =2λ

|f.sub.x |; and

space="preserve" listing-type="equation">Δ

r.sub.y.sup.2 =2λ

|f.sub.y |;

in which;

Δ

r_x² represents the periodicity in r² along the X direction;

Δ

r_y² represents the periodicity in r² along the Y direction;

λ

represents the means utilization wavelength;

f_x represents the desired focal length in the X direction; and

f_y represents the desired focal length in the Y direction.

2. A lens according to claim 1, wherein the diffractive components have elliptical outlines defined by the equation:

space="preserve" listing-type="equation">x.sup.2 /|f.sub.x |+y.sup.2 /|f.sub.y |=2λ

k

where k represents an integer.

3. A lens according to claim 1, wherein the diffractive components have hyperbolic outlines defined by the equations:

space="preserve" listing-type="equation">x.sup.2 /|f.sub.x |-y.sup.2 /|f.sub.y |=2λ

k; and

space="preserve" listing-type="equation">y.sup.2 /|f.sub.y |-x.sup.2 /|f.sub.x |=2λ

k

in which k represents an integer.

4. A lens according to claim 1, wherein the diffractive components are made by index variation.

5. A lens according to claim 1, wherein the diffractive components have a pure kinoform type phase profile varying between 0 and 2π

.

6. A lens according to claim 1, wherein the diffractive components have a sampled kinform type phase profile comprising n subzones at phase differences of 2π

/n.

7. A lens according to claim 1, wherein the diffractive components have a binary phase profile comprising two subzones at a phase difference of π

.