Imaging system having a blurring optical element for minimizing moire phenomenon

• US 5,121,213 A
• Filed: 04/12/1990
• Issued: 06/09/1992
• Est. Priority Date: 02/25/1987
• Status: Expired due to Term

• Current Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Original Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Inventors: Nishioka, Kimihiko
• Primary Examiner(s): Groody, James J.
• Assistant Examiner(s): Hsia, Sherrie
• Application Number:
  US07/511,356
• Time in Patent Office: 789 Days
• Field of Search: 358/213.11, 358/225, 358/55, 358/98, 128/4, 128/6, 350/433, 350/447, 350/286
• US Class Current: 348/335
• CPC Class Codes: G02B 23/26 using light guides for illumination G02B23/2469
• CPC Class Codes: G02B 27/0025 for optical correction, e.g. distorsion, aberration
• CPC Class Codes: H04N 23/55 Optical parts specially adapted for electronic image sensors; Mounting thereof

Abstract

An image pickup device using a solid-state image sensor adapted to provide an optical component having a multiple curved surface, polyhedral surface, symmetric cylindrical surface, axially symmetric aspherical surface or asymmetric refracting surface in an objective lens system, or lengthen a shape of an image formed on an exit end face of an illuminating optical system in a direction parallel to a scanning direction of the solid-state image sensor, or select an angle made by a line segment connecting between the centers of individual exit end faces of two illuminating optical systems with the scanning direction of the solid-state image sensor to ±40° or less, or extend a shape of an aperture of a stop in a direction parallel to the scanning direction of the solid-state image sensor, in order to make it possible to fabricate the device in a small size and at a low cost and eliminate moire and false color without reducing resolving power.

Claims

1. An imaging system for minimizing moire phenomenon comprising:

a solid-state image sensor;

an objective lens unit for forming an image of an object onto said solid-state image sensor; and

an optical element provided with one of symmetric cylindrical surface, axially symmetric aspherical surface and asymmetric refracting surface provided in an optical path from a front end of said objective lens unit to the solid-state image sensor,

each of said symmetric cylindrical surface, said axially symmetric aspherical surface and said asymmetric refracting surface allowing a blurred image of the object to be formed onto said solid-state image sensor.

2. An imaging system according to claim 1, wherein said objective lens unit includes a stop and said symmetric cylindrical surface, said axially symmetric aspherical surface and said asymmetric refracting surface are each arranged adjacent to said stop.

3. An imaging system for minimizing moire phenomenon comprising:

an objective lens unit for forming an image of an object at a predetermined imaging position, said objective lens unit including an optical element having one of a multiple curved surface compounded of plural curved surfaces, symmetric cylindrical surface, asymmetric aspherical surface, and asymmetric refracting surface,

said multiple curve surface allowing a multiple image of the object to be formed at said predetermined imaging position, and

each of said symmetric cylindrical surface, said asymmetric aspherical surface and said asymmetric refracting surface allowing a blurred image of the object to be formed at said predetermined imaging position.

4. An imaging system according to claim 3, wherein said objective lens unit is provided with a stop and said optical element is disposed adjacent to said stop.

7. An imaging system according to any one of claims 3, 4, 5 or 6, further including a solid-state image sensor disposed at said predetermined imaging position.

8. An imaging system according to claim 7 wherein said optical element has an entrance face and an exit face, one of which has a shape formed as a plurality of spherical surfaces equal in radius of curvature to each other.

9. An imaging system according to claim 8 wherein said plurality of spherical surfaces are symmetrically arranged with respect to an optical axis of said objective lens unit.

10. An imaging system according to claim 9 wherein said plurality of spherical surfaces is a pair of spherical surfaces arranged along a vertical scanning direction of said solid-state image sensor and the formula:

space="preserve" listing-type="equation">P.sub.y /4≦

D.sub.2 +D.sub.2 ≦

4P.sub.Y

is satisfied where P_y is the dimension of one pixel element of said solid-state image sensor in a vertical direction and D₂ and D₂ are decentering amounts of said two spherical surfaces.

11. An imaging system according to claim 8 wherein said plurality of spherical surfaces is a pair of spherical surface arranged along a horizontal scanning direction of said solid-state image sensor and the formula:

space="preserve" listing-type="equation">Px/4≦

D.sub.2 +D.sub.2 ≦

4P.sub.x

is satisfied where P_x is the dimension of one pixel element of the solid-state image sensor in a horizontal direction and Dp₂ and D₂ are decentering amounts of two spherical surfaces.

5. An imaging system for minimizing moire phenomenon comprising:

an objective lens unit for forming an image of an object at a predetermined imaging position,

said objective lens unit being located so that an optical element having one of a multiple curved surface compounded of plural curved surfaces, symmetric cylindrical surface, asymmetric aspherical surface and asymmetric refracting surface is arranged in an optical path from a front end of said objective lens unit to said predetermined imaging position,

said multiple curved surface allowing a multiple image of the object to be formed at said predetermined imaging position, each of said symmetric cylindrical surface, said asymmetric aspherical surface and asymmetric refracting surface allowing a blurred image of the object to be formed at said predetermined imaging position,

said multiple curved surface, said symmetric cylindrical surface, said asymmetric aspherical surface and said asymmetric refracting surface being arranged at a position such that the formula;

space="preserve" listing-type="equation">{he/hm{≦

1

is satisfied where hm is the height of an on-axial marginal ray in the multiple curved surface, symmetric cylindrical surface, asymmetric aspherical surface and asymmetric refracting surface and he is the height of an off-axial principal ray of the maximum field angle in the multiple curved surface, symmetric cylindrical surface, asymmetric aspherical surface and asymmetric refracting surface.

6. An imaging system for minimizing moire phenomenon comprising:

an objective lens unit comprised of a plurality of lenses, for forming an image of an object at a predetermined imaging position; and

a stop,

one of a multiple curved surface compounded of plural curved surfaces, symmetric cylindrical surface, asymmetric aspherical surface and asymmetric refracting surface being formed on the surface of either of lenses including the second one from the stop,

said multiple curved surface allowing a multiple image of the object to be formed at said predetermined imaging position,

each of said symmetric cylindrical surface, said asymmetric aspherical surface and said asymmetric refracting surface allowing a blurred image of the object to be formed at said predetermined imaging position.

12. An imaging system for minimizing moire phenomenon comprising:

an objective lens unit for forming an image of an object at a predetermined imaging position; and

a solid-state image sensor arranged adjacent to said predetermined imaging position,

said objective lens unit including an optical element in an optical path from a front end of said objective lens unit to said predetermined imaging position,

said optical element having an entrance face and an exit face, one of which is divided into a plurality of sections and said image of the object being separated into a plurality of images shifted in position each other at said predetermined imaging position,

a separate distance of two images measured along one of a horizontal direction and vertical direction of said image sensor, among said plurality of images, being determined so that when a distance between the separated images is taken as D₂ and D₂, one of the formula;

##EQU7## is satisfied where Px is the dimension of one pixel element of the solid-state image sensors in said horizontal direction and P_y is the dimension of one pixel element of the solid-state image sensor in said vertical direction.

13. An imaging system for minimizing moire phenomenon comprising:

a solid-state image sensor;

an objective lens unit for forming an image of an object onto said solid-state image sensors;

a stop; and

an optical element having a front light incident lens surface and a rear light transmitting surface, said rear light transmitting surface consisting of a plurality of compounded curved surfaces, said optical element provided at a position adjacent to said stop and along an optical path from a front end of said objective lens unit to said solid-state image sensor, said rear light transmitting surface allowing a multiple image of the object to be formed onto said solid-state image sensor.

14. An imaging system comprising:

an image guide fiber bundle for transmitting an image onto an exit end face of said image guide fiber bundle;

an imaging lens for receiving said image from said exit end face and developing the image at a predetermined imaging location; and

an optical element having one side of a lens surface defined by plural curved surfaces is positioned along an optical path between a front end of said imaging lens and the predetermined imaging location, said lens surface transforming the image transmitted onto said exit end face of the image guide fiber bundle into plurality images at the predetermined imaging location,

wherein said lens surface defined by plural curved surfaces is arranged in a position satisfying the condition;

space="preserve" listing-type="equation">|hc/hm|≦

1

where hm is the height of an on-axial marginal ray and hc is the height of an off-axial principal ray of the maximum field angle of said lens surface.

15. An imaging system comprising:

an image guide fiber bundle for transmitting an image onto an exit end face of said image guide fiber bundle;

an imaging lens for receiving said image from said exit end face and developing the image at a predetermined imaging location; and

an optical element having one side of a lens surface defined by one of a symmetric cylindrical surface, an asymmetric aspherical surface, and an asymmetrical refracting surface is positioned along an optical path between a front end of said imaging lens and the predetermined imaging location, said lens surface for transforming the image transmitted onto said exit end face of the image guide fiber bundle into a blurred image at the predetermined imaging location,

wherein said lens surface defined by one of a symmetric cylindrical surface, an asymmetric aspherical surface, and an asymmetric refracting surface is arranged in a position satisfying the condition;

space="preserve" listing-type="equation">|hc/hm|≦

1

where hm is the height of an on-axial marginal ray and hc is the height of an off-axial principal ray of the maximum field angle in said lens surface.