Hybrid refractive/diffractive achromatic camera lens and camera using such

• US 5,581,405 A
• Filed: 08/17/1994
• Issued: 12/03/1996
• Est. Priority Date: 12/29/1993
• Status: Expired due to Fees

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Bietry, Joseph R., Meyers, Mark M.
• Primary Examiner(s): Henry, Jon W.
• Application Number:
  US08/292,349
• Time in Patent Office: 839 Days
• Field of Search: 359/565, 359/566, 359/569, 359/571, 354/96
• US Class Current: 359/571
• 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 27/4211 correcting chromatic aberrations G02B27/0056, G02B27/4222, G02B27/4227 take precedence
• 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 5/1895 such optical elements having dioptric power

Abstract

A hybrid refractive and diffractive achromatic lens suited for single-use or inexpensive single-lens cameras operating in visible spectral range. The lens comprises a body of optically transmissive material having an index of refraction at a wavelength approximately at the center of said range of at least 1.45. The lens body having a first and second surface on opposite sides thereof, at least one of said surfaces being curved to provide a refractive portion having power and introduces chromatic aberration, the lens having a diffractive portion having power which substantially achromatizes the lens for the chromatic aberration of the refraction portion over about 440 nm to about 650 nm range.

Claims

1. A consumer camera for use in visible applications comprising:

(i) an optical system consisting of a single refractive/diffractive lens component having radii of curvature and a diffraction surface profile sufficient to achromatize said optical system over the entire visible spectrum;

(ii) a film for imaging an object by said refractive/diffractive lens component; and

(iii) a camera body enclosing said film and a portion of said refractive/diffractive lens component, wherein said hybrid refractive/diffractive lens component comprises a lens component body of optically transmissive material having an index of refraction at a wavelength approximately in the center of the visible spectrum of at least 1.45, said lens component body having first and second surfaces on opposite sides thereof, at least one of said surfaces being curved to provide a refractive portion having power and introduces chromatic aberration, said lens component having a diffractive portion having power which substantially achromatizes said lens for said chromatic aberration of said refractive portion over about 440 nm to about 650 nm, and 9<

f#;

where f# is an f-number of the optical system.

2. A camera according to claim 1, wherein said film has a film portion which has a cylindrical shape.

3. A camera according to claim 2, wherein said film has a radius of curvature R such that 85<

R<

200 mm.

4. A camera according to claim 1 further having a diaphragm or an aperture stop located between said lens component and said film.

5. A camera for use in visible applications comprising:

(i) an optical system comprising a refractive/diffractive lens component having radii of curvature and a diffraction surface profile sufficient to achromatize said optical system over visible spectrum;

(ii) a film for imaging on an object by said refractive/diffractive lens component; and

(iii) a camera body enclosing said film and a portion of said refractive/diffractive lens, wherein said film has a film portion which has a cylindrical shape.

6. A camera according to claim 5, wherein said film portion has a radius of curvature R such that 85<

R<

200 mm.

7. A camera according to claim 5, wherein said refractive/diffractive lens component comprises a body of optically transmissive material having an index of refraction at a wavelength approximately in the center of the visible spectrum of at least 1.45, said body having first and second surfaces on opposite sides thereof, at least one of said surfaces being curved to provide a refractive portion having power and introduces chromatic aberation, said lens having a diffractive portion having power which substantially achromatizes said lens for said chromatic aberration of said refractive portion over about 440 mm to about 650 nm.

11. A camera according to claim 5, wherein said lens component has the radii of curvature, thickness and an aspheric profile so that,

12. A camera according to claim 11, wherein

8. A camera for use in visible applications comprising:

(i) an optical system comprising a refractive/diffractive lens component having radii of curvature and a diffraction surface profile sufficient to achromatize said optical system over visible spectrum;

(ii) a film for imaging on an object by said refractive/diffractive lens component; and

(iii) a camera body enclosing said film and a portion of said refractive/diffractive lens, wherein said lens component has the radii of curvature, thickness and an aspheric profile so that,

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

f#<

12

space="preserve" listing-type="equation">26<

f<

34 mm

space="preserve" listing-type="equation">|±

30°

|<

w

where f# is a f# of the lens, f is the focal lens of the lens, and w is the half field angle of the lens.

9. A camera according to claim 8, wherein said refractive/diffractive lens components has an asphere on at least of its surfaces.

10. A camera according to claim 8, wherein said refractive/diffractive component has a blazed diffractive surface.

13. A consumer camera for use in visible applications comprising:

(i) an optical system having an f-number greater than 9, said optical system comprising a single hybrid refractive/diffractive lens component having radii of curvature and a diffraction surface profile sufficient to achromatize said optical system over the entire visible spectrum said hybrid refractive/diffractive lens component comprises a body of optically transmissive material having an index of refraction at a wavelength approximately in the center of the visible spectrum of at least 1.45, said lens component body having first and second surfaces on opposite sides thereof, at least one of said surfaces being curved to provide a refractive portion having power and which introduces chromatic aberration, said lens having a diffractive portion having power which substantially achromatizes said lens component for said chromatic aberration of said refractive portion over about 440 nm to about 650 nm

(ii) a film for imaging an object by said refractive/diffractive lens component; and

(iii) a camera body enclosing said film and a portion of said refractive/diffractive lens component.

14. A camera according to claim 13 wherein said refractive portion has about 85-97% of the total power of the lens.

15. A camera according to claim 13, wherein said diffractive portion has an Abbe ν

-number, ν

_diff, and said ν

_diff is negative.

16. A camera according to claim 13, wherein the diffractive portion introduces a phase delay φ

which can be described by the following equation;

##EQU20## where λ

_o is the wavelength in the center of said range, A₂, A₄, A₆, A₈, A₁₀, are phase terms, A₂ =1/(2f), where f is the focal length of the diffractive portion and A₄, A₆, A₈, and A₁₀ affect monochromatic aberration and depend upon the aspheric coefficients, AD, AE, AF and AG of the curved surface where Z is the surface sag from a plane perpendicular to the optical axis tangent to the curved surface where;

##EQU21## where C is the curvature of the curved surface measured along the radial coordinate r from a point on the optical axis.

17. A camera according to claim 13, wherein the power of the refractive portion φ

_ref, and the power of the diffractive portion φ

_diff add to provide the total power φ

_tot of the lens, are proportional such that the longitudinal chromatic aberration is approximately zero and are defined in accordance with the Abbe ν

-number, ν

_diff and ν

_ref of the diffractive and refractive portions as follows;

##EQU22##