Claims
- 1. An objective optical system for endoscopes consisting of, in order from an object side:
- a front lens unit consisting of a single lens component having a negative refractive power;
- an aperture stop; and
- a rear lens unit consisting of a single lens component having a positive refractive power;
- wherein said objective optical system satisfies the following conditions:
- CJ<8IH
- D.sub.2 <2f
- wherein said reference symbol CJ represents a distance as measured from a first surface of said objective optical system to a paraxial image surface thereof, said reference symbol IH designates a maximum image height, said reference symbol D.sub.2 represents a distance as measured from an image side surface of said negative single lens component to said aperture stop, and said reference symbol f designates a focal length of said objective optical system as a whole.
- 2. An objective optical system for endoscopes according to claim 1, wherein said single lens component of said rear lens unit consists of a single converging lens element.
- 3. An objective optical system for endoscopes according to claim 1, wherein said single lens component of said rear lens unit is a cemented lens component consisting of:
- a diverging lens element having a concave surface on an image side; and
- a biconvex converging lens element.
- 4. An objective optical system for endoscopes according to claim 2, wherein an absolute value of a radius of curvature on an object side surface of said rear lens unit is larger than an absolute value of a radius of curvature on an image side surface of said rear lens unit.
- 5. An objective optical system for endoscopes according to claim 1, wherein said system satisfies the following condition:
- .nu..sub.1 >40
- wherein the reference symbol .nu..sub.1 represents an Abbe's number of a lens component disposed on said object side of said objective optical system.
- 6. An objective optical system for endoscopes comprising, in order from an object side:
- a front lens unit consisting of a single lens component having a negative refractive power;
- an aperture stop; and
- a rear lens unit consisting of a single lens component having a positive refractive power;
- wherein said objective optical system satisfies the following conditions:
- CJ<8IH
- D.sub.2 <2f
- wherein said reference symbol CJ represents a distance as measured from a first surface of said objective optical system to a paraxial image surface thereof and said reference symbol IH designates a maximum image height, said reference symbol D.sub.2 represents a distance as measured from an image side surface of said negative single lens component to said aperture stop and said reference symbol f designates a focal length of said objective optical system as a whole; and
- wherein said front lens unit has a coating on a concave surface thereof which cuts off YAG laser light.
- 7. An objective optical system for endoscopes comprising, in order from an object side:
- a front lens unit consisting of a single lens component having a negative refractive power;
- an aperture stop; and
- a rear lens unit consisting of a single lens component having a positive refractive power;
- wherein said objective optical system satisfies the following conditions:
- CJ<8IH
- D.sub.2 <2f
- where said reference symbol CJ represents a distance as measured from a first surface of said objective optical system to a paraxial image surface thereof and said reference symbol IH designates a maximum image height, said reference symbol D.sub.2 represents a distance as measured an image side surface of said negative single lens component to said aperture stop and said reference symbol f designates a focal length of said objective optical system as a whole; and
- wherein said lens component of said rear lens unit is made of material which absorbs infrared light and is disposed immediately after said aperture stop.
- 8. An objective optical system for endoscopes according to claim 1, wherein said front lens unit has a convex surface on an object side thereof.
- 9. An objective optical system for endoscopes according to claim 2, wherein said system satisfies the following condition:
- 0.3<.vertline.f.sub.2 /f.sub.1 .vertline.<2
- wherein said reference symbol f.sub.1 represents a focal length of said front lens unit and said reference symbol f.sub.2 designates a focal length of said rear lens unit.
- 10. An objective optical system for endoscopes according to claim 2, wherein said system satisfies the following condition:
- .nu..sub.2 >40
- wherein said reference symbol .nu..sub.2 represents an Abbe's number of a lens component in said rear lens unit.
- 11. An objective optical system for endoscopes according to claim 3, wherein said system satisfies the following condition:
- .nu..sub.2d <.nu..sub.3d
- wherein said reference symbol .nu..sub.2d represents an Abbe's number of a first lens element of said rear lens unit and said reference symbol .nu..sub.3d designates an Abbe's number of a second lens element of said rear lens unit.
- 12. An objective optical system for endoscopes according to claim 3, wherein said system satisfies the following condition:
- .nu..sub.2d <35
- wherein said reference symbol .nu..sub.2d represents an Abbe's number of a first lens element of said rear lens unit.
- 13. An objective optical system for endoscopes according to claim 11, comprising at least one aspherical surface.
- 14. An objective optical system for endoscopes according to claim 13, wherein said aspherical surface satisfies the following condition:
- E.sub.i '(n.sub.i-1 -n.sub.i)>0
- wherein said reference symbols n.sub.i-1 and n.sub.i represent refractive indices of media located on an object side and an image side respectively of said aspherical surface, and said reference symbol E.sub.i ' designates an aspherical surface coefficient of a fourth order of said aspherical surface.
- 15. An objective optical system for endoscopes according to claim 13, wherein said aspherical surface satisfies the following condition:
- .DELTA.x(h.sub.m).multidot.(n.sub.i-1 -n.sub.i)>0
- wherein said reference symbols n.sub.i-1 and n.sub.i represent refractive indices of media located on an object side and an image side respectively of said aspherical surface, and said reference symbol .DELTA.x(h.sub.m) designates a departure of said aspherical surface from a reference sphere thereof as measured at a height of h.sub.m of a marginal ray on said aspherical surface.
- 16. An objective optical system for endoscopes according to any one of claims 14 or 15, wherein said aspherical surface is used as an image side surface of said rear lens unit.
- 17. An objective optical system for endoscopes comprising, from an object side:
- a front lens unit consisting of a single lens component having a negative refractive power;
- an aperture stop; and
- a rear lens unit consisting of a single lens component consisting of a single converging lens element having a positive refractive power;
- wherein said objective optical system satisfies the following conditions:
- CJ<8IH
- D.sub.2 <2f
- wherein said reference symbol CJ represents a distance as measured from a first surface of said objective optical system to a paraxial image surface thereof and said reference symbol IH designates a maximum image height, said reference symbol D.sub.2 represents a distance as measured from an image side surface of said negative single lens component to said aperture stop and said reference symbol f designates a focal length of said objective optical system as a whole;
- wherein said rear lens unit has an image side surface configured as an aspherical surface and said aspherical surface satisfies the following conditions:
- E.sub.i '(n.sub.i-1 -n.sub.i)>0
- F.sub.i '(n.sub.i-1 -n.sub.i)>0
- wherein said reference symbols n.sub.i-1 and n.sub.i represent refractive indices of media located on an object side and an image side respectively of said aspherical surface, and said reference symbols E.sub.i ' and F.sub.i ' designate aspherical surface coefficients of a fourth order and a sixth order respectively of said aspherical surface.
- 18. An objective optical system for endoscopes comprising, in order from an object side:
- a front lens unit consisting of a single lens component having a negative refractive power;
- an aperture stop; and
- a rear lens unit consisting of a single lens component consisting of a single converging lens element having a positive refractive power;
- wherein said object optical system satisfies the following conditions:
- CJ<8IH
- D.sub.2 <2f
- wherein said reference symbol CJ represents a distance as measured from a first surface of said objective optical system to a paraxial image surface thereof and said reference symbol IH designates a maximum image height, said reference symbol D.sub.2 represents a distance as measured from an image side surface of said negative single lens component to said aperture stop and said reference symbol f designates a focal length of said objective optical system as a whole;
- wherein said rear lens unit has an image side surface configured as an aspherical surface and said aspherical surface satisfies the following conditions:
- .DELTA.x(h.sub.m).multidot.(n.sub.i-1 -n.sub.i)>0
- F.sub.i '(n.sub.i-1 -n.sub.i)>0
- wherein said reference symbols n.sub.i-1 and n.sub.i represent refractive indices of media located on an object side and an image side respectively of said aspherical surface, said reference symbol .DELTA.x(h.sub.m) designates a departure of said aspherical surface from a reference sphere thereof as measured at a height of h.sub.m of a marginal ray on said aspherical surface and said reference symbol F.sub.i ' denotes an aspherical surface coefficient of a sixth order of said aspherical surface.
- 19. An objective optical system for endoscopes consisting of two only single lens components and an aperture stop, one of said lens components having a negative refractive power and the other of said lens components having a positive refractive power;
- said aperture stop being between said single lens components and said single lens component having said negative refractive power being closest to an object side of said system; and
- said objective optical system satisfying the following condition:
- CJ<8IH
- D.sub.2 <2f
- wherein said reference symbol CJ represents a distance as measured from a first surface of said objective optical system to a paraxial image surface thereof and said reference symbol IH designates a maximum image height, said reference symbol D.sub.2 represents a distance as measured from an image side surface of said negative single lens component to said aperture stop, and said reference symbol f designates a focal length of said objective optical system as a whole.
- 20. An objective optical system for endoscopes comprising, in order from an object side:
- a front lens unit consisting of a single lens component having a negative refractive power;
- an aperture stop; and
- a rear lens unit consisting of a single lens component having a positive refractive power, an absolute value of a radius of curvature on an object side surface of said rear lens unit being larger than an absolute value of a radius of curvature on an image side surface of said rear lens unit, and said single lens component of said rear lens unit is a cemented lens component consisting of:
- a diverging lens element having a concave surface on an image side, and
- a biconvex lens element;
- said objective optical system satisfying the following conditions:
- CJ<8IH
- D.sub.2 <2f
- wherein said reference symbol CJ represents a distance as measured from a first surface of said objective optical system to a paraxial image surface thereof, said reference symbol IH designates a maximum image height, said reference symbol D.sub.2 represents a distance as measured from an image side surface of said negative single lens component to said aperture stop, and said reference symbol f designates a focal length of said objective optical system as a whole.
Priority Claims (2)
Number |
Date |
Country |
Kind |
4-156218 |
May 1992 |
JPX |
|
4-237592 |
Aug 1992 |
JPX |
|
Parent Case Info
This is a continuation of application No. 08/065,784, filed on May 24, 1993, which was abandoned upon the filing hereof.
US Referenced Citations (3)
Foreign Referenced Citations (3)
Number |
Date |
Country |
56-25709 |
Mar 1981 |
JPX |
63-84109 |
Jun 1988 |
JPX |
2-77712 |
Mar 1990 |
JPX |
Continuations (1)
|
Number |
Date |
Country |
Parent |
65784 |
May 1993 |
|