Optical system

• US 6,201,648 B1
• Filed: 09/24/1999
• Issued: 03/13/2001
• Est. Priority Date: 12/02/1996
• Status: Expired due to Term

• Current Assignee: Olympus Optical Company Ltd. (Olympus Corporation)
• Original Assignee: Olympus Optical Company Ltd. (Olympus Corporation)
• Inventors: Togino, Takayoshi
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): SCHWARTZ, JORDAN MARC
• Application Number:
  US09/404,779
• Time in Patent Office: 536 Days
• Field of Search: 359/720, 359/726-728, 359/868, 359/368, 359/372-378, 359/656-661, 359/678, 359/837
• US Class Current: 359/728
• CPC Class Codes: G02B 17/08 Catadioptric systems used in non-imaging applications G02B19/00
• CPC Class Codes: G02B 17/0816 off-axis or unobscured systems in which not all of the mirrors share a common axis of rotational symmetry, e.g. at least one of the mirrors is warped, tilted or decentered with respect to the other elements
• CPC Class Codes: G02B 17/0832 off-axis or unobscured systems in which not all of the mirrors share a common axis of rotational symmetry, e.g. at least one of the mirrors is warped, tilted or decentered with respect to the other elements
• CPC Class Codes: G02B 17/0848 off-axis or unobscured systems in which not all of the mirrors share a common axis of rotational symmetry, e.g. at least one of the mirrors is warped, tilted or decentered with respect to the other elements
• CPC Class Codes: G02B 17/086 wherein the system is made of a single block of optical material, e.g. solid catadioptric systems
• CPC Class Codes: G02B 7/10 by relative axial movement of several lenses, e.g. of varifocal objective lens

Abstract

A compact optical system for microscope, endscope and binoculars capable of providing a clear image of minimal distortion even at a wide field angle. The optical system is a decentered optical system. Curved surfaces constituting the optical system include at least one rotationally asymmetric surface having no axis of rotational symmetry in or out of the surface. To correct rotationally asymmetric aberrations due to decentration by the rotationally asymmetric surface, the following condition is satisfied:

−1000<FX/FXn<1000

where FX is the focal length in the X-direction of the optical system, and FXn is the focal length in the X-direction of a portion of the rotationally asymmetric surface on which an axial principal ray strikes.

Claims

1. A microscope comprising:

an optical system provided in said microscope;

wherein said optical system has at least an optical surface for one of transmitting light rays and reflecting light rays, said optical surface having a curved shape, said curved surface having no axis of rotational symmetry into or out of said optical surface, wherein rotationally asymmetric aberrations due to decentration are corrected by the rotationally asymmetric surface, and

wherein said optical system comprises a first reflecting surface, a second reflecting surface, and a first transmitting surface, wherein light rays enter the optical system through the first transmitting surface and are reflected by the first reflecting surface and then reflected by the second reflecting surface to exit from the optical system through the first transmitting surface.

12. The microscope as set forth in claim 1, 2, 6 or 11, wherein the rotationally asymmetric surface is a plane-symmetric three-dimensional surface having only one plane of symmetry.

13. The microscope as set forth in claim 12, wherein a plane of symmetry of said rotationally asymmetric surface is disposed in a plane approximately coincident with a decentration plane, which is a direction of decentration of each surface constituting the optical system.

14. The microscope as set forth in claim 1, 2, 6 or 11, wherein said rotationally asymmetric surface is a reflecting surface.

15. The microscope as set forth in claim 14, wherein said reflecting surface is a surface having totally reflecting action.

16. The microscope as set forth in claim 12, wherein said rotationally asymmetric surface having only one plane of symmetry is a back-coated mirror.

17. The microscope as set forth in claim 1, 2, 6 or 11, wherein said rotationally asymmetric surface is tilted with respect to a principal ray which is a light ray emanating from a center of an object point and passing through a center of a pupil to reach a center of an image.

18. The microscope as set forth in claim 1, 2, 6 or 11, wherein a light ray emanating from the center of an object point and passing through the center of a pupil to reach the center of an image is defined as a principal ray, and a Y-axis is taken in the decentration plane of the surface, and an X-axis is taken in a direction perpendicularly intersecting the Y-axis, and further an axis constituting an orthogonal coordinate system in combination with the X- and Y-axes is defined as a Z-axis, and further said principal ray and a light ray which is parallel to said principal ray at a distance d in the X-axis direction are made to enter said optical system from an entrance side thereof, and the sine of an angle formed between said two rays as projected on the XZ-plane at an exit side of said optical system is denoted by NA′

X, and further that a value obtained by dividing the distance d between said parallel rays by the NA′

X is denoted by FX, and the focal length in the X-axis direction of a portion of said rotationally asymmetric surface on which the axial principal ray strikes is denoted by FXn, the following condition is satisfied;

19. The microscope as set forth in claim 1, 2, 6 or 11, wherein a light ray emanating from the center of an object point and passing through the center of a pupil to reach the center of an image is defined as a principal ray, and a Y-axis is taken in the decentration plane of the surface, and an X-axis is taken in a direction perpendicularly intersecting the Y-axis, and further an axis constituting an orthogonal coordinate system in combination with the X- and Y-axes is defined as a Z-axis, and further said principal ray and a light ray which is parallel to said principal ray at a distance d in the Y-axis direction are made to enter said optical system from the entrance side thereof, and the sine of an angle formed between said two rays in the YZ-plane at the exit side of said optical system is denoted by NA′

Y, and further a value obtained by dividing the distance d between said parallel rays by the NA′

Y is denoted by FY, and the focal length in the Y-axis direction of a portion of said rotationally asymmetric surface on which the axial principal ray strikes is denoted by FYn, the following condition is satisfied;

20. The microscope as set forth in claim 1, 2, 6 or 11, wherein a light ray emanating from the center of an object point and passing through the center of a pupil to reach the center of an image is defined as a principal ray, and a Y-axis is taken in the decentration plane of the surface, and an X-axis is taken in a direction perpendicularly intersecting the Y-axis, and further an axis constituting an orthogonal coordinate system in combination with the X- and Y-axes is defined as a Z-axis, and further said principal ray and a light ray which is parallel to said principal ray at a distance d in the X-axis direction are made to enter said optical system from an entrance side thereof, and the sine of an angle formed between said two rays as projected on the XZ-plane at the exit side of said optical system is denoted by NA′

X, and a value obtained by dividing the distance d between said parallel rays by the NA′

X is denoted by FX, and further the principal ray and a light ray which is parallel to the principal ray at a distance d away from it in the Y-axis direction are made to enter said optical system from the entrance side thereof, and the sine of an angle formed between said two rays in the YZ-plane at the exit side of said optical system is denoted by NA′

Y, and a value obtained by dividing the distance d between said parallel rays by the NA′

Y is denoted by FY, the following condition is satisfied;

35. The microscope as set forth in claim 1, 2, 6 or 11, wherein said optical system is disposed in an objective optical system of said microscope.

36. The microscope as set forth in claim 35, wherein said objective optical system has a reflecting surface forming a folded optical path, and wherein said reflecting surface forming said folded optical path has power.

37. The microscope as set forth in claim 36, further comprising an ocular optical system for observing an image formed by said objective optical system, a combination of the objective optical system and the ocular optical system forms an afocal optical system.

38. The microscope as set forth in claim 37, wherein said afocal optical system is arranged to obtain an erect image by an even number of reflections.

39. The microscope as set forth in claim 1, 2, 6 or 11, wherein said optical system is disposed in an ocular optical system for said microscope.

40. The microscope as set forth in claim 39, wherein said ocular optical system has a reflecting surface for forming a folded optical path, and wherein said reflecting surface forming said folded optical path has power.

41. The microscope as set forth in claim 40, further comprising an objective optical system for observing an image formed by said ocular optical system, wherein a combination of the objective optical system and the ocular optical system forms an afocal optical system.

42. The microscope as set forth in claim 41, wherein said afocal optical system is arranged to obtain an erect image by an even number of reflections.

43. The microscope as set forth in claim 1, 2, 6 or 11, wherein said optical system is disposed in an intermediate-image relay optical system for said microscope.

44. The microscope as set forth in claim 1, 2, 6 or 11, wherein said optical system is disposed in an illumination system for said microscope.

45. The microscope as set forth in claim 1, 2, 6 or 11, wherein said optical system is disposed in an incident-light illumination system for microscope.

46. The microscope as set forth in claim 1, 2, 6 or 11, wherein said optical system is disposed in a transmission illumination system for said microscope.

47. The microscope as set forth in claim 1, 2, 6 or 11, wherein said optical system is disposed in a multi-discussion lens barrel for said microscope.

48. The microscope as set forth in claim 1, 2, 6 or 11, wherein said optical system is disposed in an optical system of an image-drawing device for said microscope.

49. The microscope as set forth in claim 1, 2, 6 or 11, wherein said optical system is disposed in an autofocus system for said microscope.

50. The microscope as set forth in claim 1, 2, 6 or 11, wherein said optical system is disposed in a projection optical system for said microscope.

51. The microscope as set forth in claim 1, 2, 6 or 11, wherein said optical system is disposed in optical means provided in a binocular stereoscopic microscope having an optical axis for a right eye and an optical axis for a left eye.

52. The microscope as set forth in claim 51, wherein said binocular stereoscopic microscope has an objective lens system common to said optical axes for said right and left eyes, said optical system being provided for each of said optical axes for said right eye and said left eye in order to correct aberrations due to decentration which are produced by said objective lens system.

53. The microscope as set forth in claim 51, wherein said optical axes for said right eye and said left eye are tilted with respect to an object plane, and two objective lens systems are provided for said two optical axes, respectively, said optical system being provided for each of said optical axes for said right and left eyes to correct aberrations produced by said two objective lens systems.

54. The microscope as set forth in claim 51, wherein said optical system is disposed closest to an object side on each of said right and left optical axes.

2. A microscope comprising:

an optical system provided in said microscope;

wherein said optical system has at least an optical surface for one of transmitting light rays and reflecting light rays, said optical surface having a curved shape, said curved surface having no axis of rotational symmetry into or out of said optical surface, wherein rotationally asymmetric aberrations due to decentration are corrected by the rotationally asymmetric surface,

wherein said optical system comprises a first reflecting surface, a second reflecting surface, a first transmitting surface, and a second transmitting surface, wherein light rays enter the optical system through the first transmitting surface and are reflected by the first reflecting surface and then reflected by the second reflecting surface to exit from the optical system through the second transmitting surface, and

wherein the first reflecting surface and the second transmitting surface are portions of single surface.

3. The microscope as set forth in claim 2, wherein said light rays define an optical path in said optical system, said optical path having intersecting portions.

4. The microscope as set forth in claim 2, wherein said light rays define an optical path in said optical system, said optical path being without intersecting portions.

5. The microscope as set forth in claim 2, wherein the first transmitting surface and the second reflecting surface are portions of a single surface.

6. A microscope comprising:

an optical system provided in said microscope;

wherein said optical system has at least an optical surface for one of transmitting light rays and reflecting light rays, said optical surface having a curved shape, said curved surface having no axis of rotational symmetry into or out of said optical surface, wherein rotationally asymmetric aberrations due to decentration are corrected by the rotationally asymmetric surface, and

wherein said optical system comprises a first reflecting surface, a second reflecting surface, a third reflecting surface, a first transmitting surface, and a second transmitting surface, wherein light rays enter the optical system through the first transmitting surface and are reflected successively by the first, second and third reflecting surfaces to exit from the optical system through the second transmitting surface in a direction different from a direction in which the light rays are incident on the first transmitting surface.

7. The microscope as set forth in claim 6, wherein the first transmitting surface and the second reflecting surface are portions of a single surface.

8. The microscope as set forth in claim 6, wherein the first reflection surface and the third reflection surface are portions of a single surface.

9. The microscope as set forth in claim 6, wherein the first transmitting surface and the third reflecting surface are portions of a single surface.

10. The microscope as set forth in claim 6, wherein the second transmitting surface and the second reflecting surface are portions of a single surface.

11. A microscope comprising:

an optical system provided in said microscope;

wherein said optical system has at least an optical surface for one of transmitting light rays and reflecting light rays, said optical surface having a curved shape, said curved surface having no axis of rotational symmetry into or out of said optical surface, wherein rotationally asymmetric aberrations due to decentration are corrected by the rotationally asymmetric surface, and

wherein said optical system comprises at least a first reflecting surface, a second reflecting surface, a third reflecting surface, a fourth reflecting surface, a first transmitting surface, and a second transmitting surface, wherein light rays enter the optical system through the first transmitting surface and are reflected successively by the first, second, third and fourth reflecting surfaces to exit from the optical system through the second transmitting surface in a direction different from a direction in which the light rays are incident on the first transmitting surface.

21. The microscope as set forth in claim 11, wherein the first transmitting surface and the second reflecting surface are portions of a single surface.

22. The microscope as set forth in claim 11, wherein the second transmitting surface and the third reflecting surface are portions of a single surface.

23. The microscope as set forth in claim 11, wherein the first reflecting surface and the third reflecting surface are portions of a single surface.

24. The microscope as set forth in claim 11, wherein the second reflecting surface and the fourth reflecting surface are portions of a single surface.

25. The microscope as set forth in claim 11, wherein the first transmitting surface, the second reflecting surface, and the fourth reflecting surface are portions of a single surface.

26. The microscope as set forth in claim 11, wherein the first transmitting surface and the second reflecting surface are portions of a single surface, and wherein the first reflecting surface and the third reflecting surface are portions of a single surface.

27. The microscope as set forth in claim 11, wherein the first transmitting surface and the second reflecting surface are portions of a single surface, and wherein the second transmitting surface and the third reflecting surface are portions of a single surface.

28. The microscope as set forth in claim 11, wherein the first reflecting surface and the third reflecting surface are portions of a single surface, and wherein the second reflecting surface and the fourth reflecting surface are portions of a single surface.

29. The microscope as set forth in claim 11, wherein the second reflecting surface and the fourth reflecting surface are portions of a single surface, and wherein the second transmitting surface and the third reflecting surface are portions of a single surface.

30. The microscope as set forth in claim 11, wherein the first transmitting surface, the second reflecting surface, and the fourth reflecting surface are portions of a single surface, and wherein the second transmitting surface and the third reflecting surface are portions of a single surface.

31. The microscope as set forth in claim 11, wherein the first transmitting surface, the second reflecting surface, and the fourth reflecting surface are portions of a single surface, and wherein the first reflecting surface and the third reflecting surface are portions of a single surface.

32. The microscope as set forth in claim 11, wherein the first transmitting surface and the second reflecting surface are portions of a single surface, and wherein the second transmitting surface, the first reflecting surface, and the third reflecting surface are portions of a single surface.

33. The microscope as set forth in claim 11, wherein the second reflecting surface and the forth reflecting surface are portions of a single surface, and wherein the second transmitting surface, the first reflecting surface, and the third reflecting surface are portions of a single surface.

34. The microscope as set forth in claim 11, wherein the first transmitting surface, the second reflecting surface, and the fourth reflecting surface are portions of a single surface, and wherein the second transmitting surface, the first reflecting surface, and the third reflecting surface are portions of a single surface.

55. An endoscope comprising:

an optical system provided in said endoscope;

wherein said optical system has at least an optical surface for one of transmitting light rays and reflecting light rays, said optical surface having a curved shape, said curved surface having no axis of rotational symmetry into or out of said optical surface, wherein rotationally asymmetric aberrations due to decentration are corrected by the rotationally asymmetric surface, and

wherein said optical system comprises a first reflecting surface, a second reflecting surface, and a first transmitting surface, wherein light rays enter the optical system through the first transmitting surface and are reflected by the first reflecting surface and then reflected by the second reflecting surface to exit from the optical system through the first transmitting surface.

66. The endoscope as set forth in claim 55, 56, 60 or 65, wherein the rotationally asymmetric surface is a plane-symmetric three-dimensional surface having only one plane of symmetry.

67. The endoscope as set forth in claim 66, wherein a plane of symmetry of said rotationally asymmetric surface is disposed in a plane approximately coincident with a decentration plane, and a direction of decentration of each surface constituting the optical system is in said decentration plane.

68. The endoscope as set forth in claim 55, 56, 60 or 65, wherein said rotationally asymmetric surface is a reflecting surface.

69. The endoscope as set forth in claim 68, wherein said reflecting surface is a surface having totally reflecting action.

70. The endoscope as set forth in claim 66, wherein said rotationally asymmetric surface having only one plane of symmetry is used as a back-coated mirror.

71. The endoscope as set forth in claim 55, 56, 60 or 65, wherein said rotationally asymmetric surface is tilted with respect to a principal ray which is a light ray emanating from a center of an object point and passing through a center of a pupil to reach a center of an image.

72. The endoscope as set forth in claim 55, 56, 60 or 65, wherein a light ray emanating from a center of an object point and passing through a center of a pupil to reach a center of an image is defined as a principal ray, and a Y-axis is taken in the decentration plane of the surface, and an X-axis is taken in a direction perpendicularly intersecting the Y-axis, and further an axis constituting an orthogonal coordinate system in combination with the X- and Y-axes is defined as a Z-axis, and further said principal ray and a light ray which is parallel to said principal ray at a distance d in the X-axis direction are made to enter said optical system from an entrance side thereof, and the sine of an angle formed between said two rays as projected on the XZ-plane at an exit side of said optical system is denoted by NA′

X, and further a value obtained by dividing the distance d between said parallel rays by the NA′

X is denoted by FX, and the focal length in the X-axis direction of a portion of said rotationally asymmetric surface on which the axial principal ray strikes is denoted by FXn, the following condition is satisfied;

73. The endoscope as set forth in claim 55, 56, 60 or 65, wherein a light ray emanating from the center of an object point and passing through the center of a pupil to reach the center of an image is defined as a principal ray, and a Y-axis is taken in the decentration plane of the surface, and an X-axis is taken in a direction perpendicularly intersecting the Y-axis, and further an axis constituting an orthogonal coordinate system in combination with the X- and Y-axes is defined as a Z-axis, and further said principal ray and a light ray which is parallel to said principal ray at a distance d in the Y-axis direction are made to enter said optical system from the entrance side thereof, and the sine of an angle formed between said two rays in the YZ-plane at the exit side of said optical system is denoted by NA′

Y, and further a value obtained by dividing the distance d between said parallel rays by the NA′

Y is denoted by FY, and the focal length in the Y-axis direction of a portion of said rotationally asymmetric surface on which the axial principal ray strikes is denoted by FYn, the following condition is satisfied;

74. The endoscope as set forth in claim 55, 56, 60 or 65, wherein a light ray emanating from a center of an object point and passing through a center of a pupil to reach a center of an image is defined as a principal ray, and a Y-axis is taken in the decentration plane of the surface, and an X-axis is taken in a direction perpendicularly intersecting the Y-axis, and further an axis constituting an orthogonal coordinate system in combination with the X- and Y-axes is defined as a Z-axis, and further said principal ray and a light ray which is parallel to said principal ray at a distance d in the X-axis direction are made to enter said optical system from an entrance side thereof, and the sine of an angle formed between said two rays as projected on the XZ-plane at the exit side of said optical system is denoted by NA′

X, and a value obtained by dividing the distance d between said parallel rays by the NA′

X is denoted by FX, and further the principal ray and a light ray which is parallel to the principal ray at a distance d away from it in the Y-axis direction are made to enter said optical system from the entrance side thereof, and the sine of an angle formed between said two rays in the YZ-plane at the exit side of said optical system is denoted by NA′

Y, and a value obtained by dividing the distance d between said parallel rays by the NA′

Y is denoted by FY, the following condition is satisfied;

89. The endoscope as set forth in claim 55, 56, 60 or 65, wherein said optical system is disposed in an endoscope objective optical system.

90. The endoscope as set forth in claim 89, wherein an imaging device is disposed at an image plain formed by said objective optical system.

91. The endoscope as set forth in claim 89, wherein said objective optical system has a reflecting surface forming a folded optical path, and wherein said reflecting surface forming said folded optical path has power.

92. The endoscope as set forth in claim 89, wherein a protective transparent plate is disposed on an object side of said optical system.

93. The endoscope as set forth in claim 89, wherein an object-side surface of said optical system is a plane surface.

94. The endoscope as set forth in claim 89, wherein an image-side surface of said optical system is a plane surface.

95. The endoscope as set forth in claim 94, wherein the image-side surface of said optical system is placed in close contact with an imaging device.

96. The endoscope as set forth in claim 89, wherein an optical fiber bundle is disposed at an image-formation plane of said objective optical system separately from said optical system.

97. The endoscope as set forth in claim 89, wherein an optical fiber bundle is disposed at an image-formation plane of said objective optical system separately from said optical system, the closest plane to said image-formation plane of said objective optical contacts said optical fiber bundle.

98. The endoscope as set forth in claim 96, wherein an object-side surface of said objective optical system is formed from a protective transparent plate.

99. The endoscope as set forth in claim 96, wherein an object-side surface of said objective system is a plane surface.

100. The endoscope as set forth in claim 89, wherein a first surface in a distal end part of the endoscope is made of one of glass and a crystalline material.

101. The endoscope as set forth in claim 89, wherein a first surface of the endoscope objective optical system is recessed from an enclosure of the endoscope.

102. The endoscope as set forth in claim 89, wherein a first surface of the endoscope objective optical system projects from an enclosure of the endoscope.

103. The endoscope as set forth in claim 55, 56, 60 or 65, further comprising a camera adapter having an imaging device, wherein said optical system is disposed in said camera adapter to project an observation image onto said imaging device through said optical system.

104. The endoscope as set forth in claim 103, wherein a plane glass plate is provided in front of or behind said optical system.

105. The endoscope as set forth in claim 103, further comprising means for varying a spacing between said optical system and an image-formation plane.

106. The endoscope as set forth in claim 103, wherein said camera adapter comprises a second optical system in addition to the first-mentioned optical system, and said endoscope has means for varying a spacing between the first-mentioned optical system and said second optical system.

107. The endoscope as set forth in claim 103, wherein said camera adapter comprises a second optical system in addition to the first-mentioned optical system, wherein a sum total of reflections taking place in the first-mentioned optical system and said second optical system is an even number.

108. The endoscope as set forth in claim 103, wherein said camera adapter for said endoscope comprises an optical system in which a sum total of reflection is an odd number, and an electrically image-inverting circuit.

109. The endoscope as set forth in claim 103, wherein said camera adapter for said endoscope has a semitransparent reflecting surface to divide an optical path into two.

110. The endoscope as set forth in claim 103, wherein an observation optical path of an observer is approximately parallel to an optical axis of light rays entering said endoscope camera adapter from an observation optical system.

111. The endoscope as set forth in claim 100, wherein said crystalline material is sapphire.

56. An endoscope, comprising:

an optical system provided in said endoscope;

wherein said optical system has at least an optical surface for one of transmitting light rays and reflecting light rays, said optical surface having a curved shape, said curved surface having no axis of rotational symmetry into or out of said optical surface, wherein rotationally asymmetric aberrations due to decentration are corrected by the rotationally asymmetric surface,

wherein said optical system comprises a first reflecting surface, a second reflecting surface, a first transmitting surface, and a second transmitting surface, wherein light rays enter the optical system through the first transmitting surface and are reflected by the first reflecting surface and then reflected by the second reflecting surface to exit from the optical system through the second transmitting surface, and

wherein the first reflecting surface and the second transmitting surface are portions of a single surface.

57. The endoscope as set forth in claim 56, wherein said light rays define an optical path in said optical system, said optical path having intersecting portions.

58. The endoscope as set forth in claim 56, wherein said light rays define an optical path in said optical system, said optical path being without intersecting portions.

59. The endoscope as set forth in claim 56, wherein the first transmitting surface and the second reflecting surface are portions of a single surface.

60. An endoscope comprising:

an optical system provided in said endoscope;

wherein said optical system has at least an optical surface for one of transmitting light rays and reflecting light rays, said optical surface having a curved shape, said curved surface having no axis of rotational symmetry into or out of said optical surface, wherein rotationally asymmetric aberrations due to decentration are corrected by the rotationally asymmetric surface, and

wherein said optical system comprises a first reflecting surface, a second reflecting surface, a third reflecting surface, a first transmitting surface, and a second transmitting surface, wherein light rays enter the optical system through the first transmitting surface and are reflected successively by the first, second and third reflecting surfaces to exit from the optical system through the second transmitting surface in a direction different from a direction in which the light rays are incident on the first transmitting surface.

61. The endoscope as set forth in claim 60, wherein the first transmitting surface and the second reflecting surface are portions of a single surface.

62. The endoscope as set forth in claim 60, wherein the first reflection surface and the third reflection surface are portions of a single surface.

63. The endoscope as set forth in claim 60, wherein the first transmitting surface and the third reflecting surface are portions of a single surface.

64. The endoscope as set forth in claim 60, wherein the second transmitting surface and the second reflecting surface are portions of a single surface.

65. An endoscope comprising:

an optical system provided in said endoscope;

wherein said optical system has at least an optical surface for one of transmitting light rays and reflecting light rays, said optical surface having a curved shape, said curved surface having no axis of rotational symmetry into or out of said optical surface, wherein rotationally asymmetric aberrations due to decentration are corrected by the rotationally asymmetric surface, and

wherein, said optical system comprises at least a first reflecting surface, a second reflecting surface, a third reflecting surface, a fourth reflecting surface, a first transmitting surface, and a second transmitting surface, wherein light rays enter the optical system through the first transmitting surface and are reflected successively by the first, second, third and fourth reflecting surfaces to exit from the optical system through the second transmitting surface in a direction different from a direction in which the light rays are incident on the first transmitting surface.

75. The endoscope as set forth in claim 65, wherein the first transmitting surface and the second reflecting surface are portions of a single surface.

76. The endoscope as set forth in claim 65, wherein the second transmitting surface and the third reflecting surface are portions of a single surface.

77. The endoscope as set forth in claim 65, wherein the first reflecting surface and the third reflecting surface are portions of a single surface.

78. The endoscope as set forth in claim 65, wherein the second reflecting surface and the fourth reflecting surface are portions of a single surface.

79. The endoscope as set forth in claim 65, wherein the first transmitting surface, the second reflecting surface, and the fourth reflecting surface are portions of a single surface.

80. The endoscope as set forth in claim 65, wherein the first transmitting surface and the second reflecting surface are portions of a single surface, and wherein the first reflecting surface and the third reflecting surface are portions of a single surface.

81. The endoscope as set forth in claim 65, wherein the first transmitting surface and the second reflecting surface are portions of a single surface, and wherein the second transmitting surface and the third reflecting surface are portions of a single surface.

82. The endoscope as set forth in claim 65, wherein the first reflecting surface and the third reflecting surface are an identical surface, and wherein the second reflecting surface and the fourth reflecting surface are portions of a single surface.

83. The endoscope as set forth in claim 65, wherein the second reflecting surface and the fourth reflecting surface are portions of a single surface, and wherein the second transmitting surface and the third reflecting surface are portions of a single surface.

84. The endoscope as set forth in claim 65, wherein the first transmitting surface, the second reflecting surface, and the fourth reflecting surface are portions of a single surface, and wherein the second transmitting surface and the third reflecting surface are portions of a single surface.

85. The endoscope as set forth in claim 65, wherein the first transmitting surface, the second reflecting surface, and the fourth reflecting surface are portions of a single surface, and wherein the first reflecting surface and the third reflecting surface are portions of a single surface.

86. The endoscope as set forth in claim 65, wherein the first transmitting surface and the second reflecting surface are an identical surface, and wherein the second transmitting surface, the first reflecting surface, and the third reflecting surface are portions of a single surface.

87. The endoscope as set forth in claim 65, wherein the second reflecting surface and the forth reflecting surface are an identical surface, and wherein the second transmitting surface, the first reflecting surface, and the third reflecting surface are portions of a single surface.

88. The endoscope as set forth in claim 65, wherein the first transmitting surface, the second reflecting surface, and the fourth reflecting surface are portions of a single surface, and wherein the second transmitting surface, the first reflecting surface, and the third reflecting surface are portions of a single surface.

112. A pair of binoculars comprising:

a right eye objective lens system and a left eye objective lens system, both said objective lens systems being provided in the binoculars;

said left eye objective lens system having at least an optical surface for one of transmitting light rays and reflecting light rays, said optical surface having a curved shape, said curved surface having no axis of rotational symmetry into or out of said optical surface, wherein rotationally asymmetric aberrations due to decentration are corrected by the rotationally asymmetric surface, and

said right eye objective lens system having at least an optical surface for one of transmitting light rays and reflecting light rays, said optical surface having a curved shape, said curved surface having no axis of rotational symmetry into or out of said optical surface, wherein rotationally asymmetric aberrations due to decentration are corrected by the rotationally asymmetric surface,

wherein the rotationally asymmetric surface is a plane-symmetric three-dimensional surface having only one plane of symmetry, and

wherein said left eye objective lens system and said right eye objective lens system each comprises a first reflecting surface, a second reflecting surface, and a first transmitting surface, wherein light rays enter each said objective lens system through the corresponding first transmitting surface and are reflected by the corresponding first reflecting surface and then reflected by the corresponding second reflecting surface to exit from each said objective lens system through the corresponding first transmitting surface.

126. The binoculars as set forth in claim 112, 113, 114, 115, 118, 119, 124 or 125, wherein the plane of symmetry of said rotationally asymmetric surface is disposed in a plane approximately coincident with a decentration plane, and a direction of decentration of each surface constituting the optical system is in said decentration plane.

127. The binoculars as set forth in claim 112, 113, 114, 115, 118, 119, 124 or 125, wherein said rotationally asymmetric surface is a reflecting surface.

128. The binoculars as set forth in claim 127, wherein said reflecting surface is a surface having totally reflecting action.

129. The binoculars as set forth in claim 112, 113, 114, 115, 118, 119, 124 or 125, wherein said rotationally asymmetric surface having only one plane of symmetry is a back-coated mirror.

130. The binoculars as set forth in claim 112, 113, 114, 115, 118, 119, 124 or 125, wherein said rotationally asymmetric surface is tilted with respect to a principal ray which is a light ray emanating from a center of an object point and passing through a center of a pupil to reach a center of an image.

131. The binoculars as set forth in claim 112, 113, 114, 115, 118, 119, 124 or 125, wherein a light ray emanating from a center of an object point and passing through a center of a pupil to reach a center of an image is defined as a principal ray, and a Y-axis is taken in the decentration plane of the surface, and an X-axis is taken in a direction perpendicularly intersecting the Y-axis, and further an axis constituting an orthogonal coordinate system in combination with the X- and Y-axes is defined as a Z-axis, and further said principal ray and a light ray which is parallel to said principal ray at a distance d in the X-axis direction are made to enter one of said objective lens systems and said ocular lens systems from an entrance side thereof, and the sine of an angle formed between said two rays as projected on the XZ-plane at an exit side of said optical system is denoted by NA′

X, and further a value obtained by dividing the distance d between said parallel rays by the NA′

X is denoted by FX, and the focal length in the X-axis direction of a portion of said rotationally asymmetric surface on which the axial principal ray strikes is denoted by FXn, the following condition is satisfied;

132. The binoculars as set forth in claim 112, 113, 114, 115, 118, 119, 124 or 125, wherein a light ray emanating from a center of an object point and passing through a center of a pupil to reach a center of an image is defined as a principal ray, and a Y-axis is taken in the decentration plane of the surface, and an X-axis is taken in a direction perpendicularly intersecting the Y-ax is, and further an axis constituting an orthogonal coordinate system in combination with the X- and Y-axes is defined as a Z-axis, and further said principal ray and a light ray which is parallel to said principal ray at a distance d in the Y-axis direction are made to enter one of said objective lens systems and said ocular lens systems from an entrance side thereof, and the sine of an angle formed between said two rays in the YZ-plane at an exit side of said optical system is denoted by NA′

Y, and further a value obtained by dividing the distance d between said parallel rays by the NA′

Y is denoted by FY, and the focal length in the Y-axis direction of a portion of said rotationally asymmetric surface on which the axial principal ray strikes is denoted by FYn, the following condition is satisfied;

133. The binoculars as set forth in claim 112, 113, 114, 115, 118, 119, 124 or 125, wherein a light ray emanating from a center of an object point and passing through a center of a pupil to reach a center of an image is defined as a principal ray, and a Y-axis is taken in the decentration plane of the surface, and an X-axis is taken in a direction perpendicularly intersecting the Y-axis, and further an axis constituting an orthogonal coordinate system in combination with the X- and Y-axes is defined as a Z-axis, and further said principal ray and a light ray which is parallel to said principal ray at a distance d in the X-axis direction are made to enter one of said objective lens systems and said ocular lens systems from an entrance side thereof, and the sine of an angle formed between said two rays as projected on the XZ-plane at the exit side of said optical system is denoted by NA′

X, and a value obtained by dividing the distance d between said parallel rays by the NA′

X is denoted by FX, and further the principal ray and a light ray which is parallel to the principal ray at a distance d away from it in the Y-axis direction are made to enter one of said objective lens systems and said ocular lens systems from the entrance side thereof, and the sine of an angle formed between said two rays in the YZ-plane at the exit side of said objective lens system or said ocular lens system is denoted by NA′

Y, and a value obtained by dividing the distance d between said parallel rays by the NA′

Y is denoted by FY, the following condition is satisfied;

149. The binoculars as set forth in claim 112, 114, 118 or 124, further comprising an objective optical system having a folded optical path comprising a reflecting surface having power.

150. The binoculars as set forth in claim 112, 114, 118 or 124, further comprising a night eye ocular optical system and a left eye ocular optical system, both said ocular optical systems being provided in the binoculars, a combination of the right and left objective lens systems and the right and left ocular optical systems forming an afocal optical system.

151. The binoculars as set forth in claim 150, wherein said afocal optical system is constructed to obtain an erect image by an even number of reflections.

113. A pair of binoculars comprising:

a right eye ocular lens system and a left eye ocular lens system, both said ocular lens systems being provided in the binoculars;

said left eye ocular lens system having at least an optical surface for one of transmitting light rays and reflecting light rays, said optical surface having a curved shape, said curved surface having no axis of rotational symmetry into or out of said optical surface, wherein rotationally asymmetric aberrations due to decentration are corrected by the rotationally asymmetric surface, and

said right eye ocular lens system having at least an optical surface for one of transmitting rays and reflecting light rays, said optical surface having a curved shape, said curved surface having no axis of rotational symmetry into or out of said optical surface, wherein rotationally asymmetric aberrations due to decentration are corrected by the rotationally asymmetric surface,

wherein the rotationally asymmetric surface is a plane-symmetric three-dimensional surface having only one plane of symmetry, and

wherein said left eye ocular lens system and said night eye ocular lens system each comprises a first reflecting surface, a second reflecting surface, and a first transmitting surface, wherein light rays enter each said ocular lens system through the corresponding first transmitting surface and are reflected by the corresponding first reflecting surface and then reflected by the corresponding second reflecting surface to exit from each said ocular lens system through the corresponding first transmitting surface.

148. The binoculars as set forth in claim 113, 115, 119 or 125, further comprising an ocular optical system having a folded optical path comprising a reflecting surface having power.

152. The binoculars as set forth in claim 113, 115, 119 or 125, further comprising a right eye objective optical system and a left eye objective optical system, both said objective optical systems being provided in the binoculars, a combination of the right and left objective optical systems and the right and left ocular lens systems forming an afocal optical system.

153. The binoculars as set forth in claim 152, wherein said afocal optical system is constructed to obtain an erect image by an even number of reflections.

114. A pair of binoculars comprising:

a right eye objective lens system and a left eye objective lens system, both said objective lens systems being provided in the binoculars;

said left eye objective lens system having at least an optical surface for one of transmitting light rays and reflecting light rays, said optical surface having a curved shape, said curved surface having no axis of rotational symmetry into or out of said optical surface, wherein rotationally asymmetric aberrations due to decentration are corrected by the rotationally asymmetric surface, and

said right eye objective lens system having at least an optical surface for one of transmitting light rays and reflecting light rays, said optical surface having a curved shape, said curved surface having no axis of rotational symmetry into or out of said optical surface, wherein rotationally asymmetric aberrations due to decentration are corrected by the rotationally asymmetric surface,

wherein the rotationally asymmetric surface is a plane-symmetric three-dimensional surface having only one plane of symmetry,

wherein said left eye objective lens system and said night eye objective lens system each comprises a first reflecting surface, a second reflecting surface, a first transmitting surface, and a second transmitting surface, wherein light rays enter each said objective lens system through the corresponding first transmitting surface and are reflected by the corresponding first reflecting surface and then reflected by the corresponding second reflecting surface to exit from each said objective lens system through the corresponding second transmitting surface, and

wherein the first corresponding reflecting surface and the second corresponding transmitting surface are portions of a single surface.

116. The binoculars as set forth in claim 114 or 115, wherein said light rays define an optical path in said optical system, said optical path having intersecting portions.

117. The binoculars as set forth in claim 114 or 115, wherein the corresponding first transmitting surface and the corresponding second reflecting surface are a same surface.

115. A pair of binoculars comprising:

a right eye ocular lens system and a left eye ocular lens system, both said ocular lens systems being provided in the binoculars;

said left eye ocular lens system having at least an optical surface for one of transmitting light rays and reflecting light rays, said optical surface having a curved shape, said curved surface having no axis of rotational symmetry into or out of said optical surface, wherein rotationally asymmetric aberrations due to decentration are corrected by the rotationally asymmetric surface, and

said right eye ocular lens system having at least an optical surface for one of transmitting rays and reflecting light rays, said optical surface having a curved shape, said curved surface having no axis of rotational symmetry into or out of said optical surface, wherein rotationally asymmetric aberrations due to decentration are corrected by the rotationally asymmetric surface,

wherein the rotationally asymmetric surface is a plane-symmetric three-dimensional surface having only one plane of symmetry,

wherein said left eye ocular lens system and said right eye ocular lens system each comprises a first reflecting surface, a second reflecting surface, a first transmitting surface, and a second transmitting surface, wherein light rays enter each said ocular lens system through the corresponding first transmitting surface and are reflected by the corresponding first reflecting surface and then reflected by the corresponding second reflecting surface to exit from each said ocular lens system through the corresponding second transmitting surface, and

wherein the first corresponding reflecting surface and the second corresponding transmitting surface are portions of a single surface.

118. A pair of binoculars comprising:

a right eye objective lens system and a left eye objective lens system, both said objective lens systems being provided in the binoculars;

said left eye objective lens system having at least an optical surface for one of transmitting light rays and reflecting light rays, said optical surface having a curved shape, said curved surface having no axis of rotational symmetry into or out of said optical surface, wherein rotationally asymmetric aberrations due to decentration are corrected by the rotationally asymmetric surface, and

said right eye objective lens system having at least an optical surface for one of transmitting light rays and reflecting light rays, said optical surface having a curved shape, said curved surface having no axis of rotational symmetry into or out of said optical surface, wherein rotationally asymmetric aberrations due to decentration are corrected by the rotationally asymmetric surface,

wherein the rotationally asymmetric surface is a plane-symmetric three-dimensional surface having only one plane of symmetry, and

wherein said left eye objective lens system and said right eye objective lens system each are integrally formed as a unitary lens structure and comprise a first reflecting surface, a second reflecting surface, a third reflecting surface, a first transmitting surface, and a second transmitting surface, wherein light rays enter each said objective lens system through the corresponding first transmitting surface and are reflected successively by the corresponding first, second and third reflecting surfaces to exit from each said objective lens system through the corresponding second transmitting surface in a direction different from a direction in which the light rays are incident on the corresponding first transmitting surface.

120. The binoculars as set forth in claim 118 or 119, wherein the corresponding first transmitting surface and the corresponding second reflecting surface are portions of a single surface.

121. The binoculars as set forth in claim 118 or 119, wherein the corresponding first reflection surface and the corresponding third reflection surface are portions of a single surface.

122. The binoculars as set forth in claim 118 or 119, wherein the corresponding first transmitting surface and the corresponding third reflecting surface are portions of a single surface.

123. The binoculars as set forth in claim 118 or 119, wherein the corresponding second transmitting surface and the corresponding second reflecting surface are portions of a single surface.

119. A pair of binoculars comprising:

a right eye ocular lens system and a left eye ocular lens system, both said ocular lens systems being provided in the binoculars;

said left eye ocular lens system having at least an optical surface for one of transmitting light rays and reflecting light rays, said optical surface having a curved shape, said curved surface having no axis of rotational symmetry into or out of said optical surface, wherein rotationally asymmetric aberrations due to decentration are corrected by the rotationally asymmetric surface, and

said right eye ocular lens system having at least an optical surface for one of transmitting rays and reflecting light rays, said optical surface having a curved shape, said curved surface having no axis of rotational symmetry into or out of said optical surface, wherein rotationally asymmetric aberrations due to decentration are corrected by the rotationally asymmetric surface,

wherein the rotationally asymmetric surface is a plane-symmetric three-dimensional surface having only one plane of symmetry, and

wherein said left eye ocular lens system and said right eye ocular lens system each are integrally formed as a unitary lens structure and comprise a first reflecting surface, a second reflecting surface, a third reflecting surface, a first transmitting surface, and a second transmitting surface wherein light rays enter each said ocular lens system through the corresponding first transmitting surface and are reflected successively by the corresponding first, second and third reflecting surfaces to exit from each said ocular lens system through the corresponding second transmitting surface in a direction different from a direction in which the light rays are incident on the corresponding first transmitting surface.

124. A pair of binoculars comprising:

a right eye objective lens system and a left eye objective lens system, both said objective lens systems being provided in the binoculars;

said left eye objective lens system having at least an optical surface for one of transmitting light rays and reflecting light rays, said optical surface having a curved shape, said curved surface having no axis of rotational symmetry into or out of said optical surface, wherein rotationally asymmetric aberrations due to decentration are corrected by the rotationally asymmetric surface, and

said right eye objective lens system having at least an optical surface for one of transmitting light rays and reflecting light rays, said optical surface having a curved shape, said curved surface having no axis of rotational symmetry into or out of said optical surface, wherein rotationally asymmetric aberrations due to decentration are corrected by the rotationally asymmetric surface,

wherein the rotationally asymmetric surface is a plane-symmetric three-dimensional surface having only one plane of symmetry, and

wherein said left eye objective lens system and said right eye objective lens system each are integrally formed as a unitary lens structure and comprise at least a first reflecting surface, a second reflecting surface, a third reflecting surface, a fourth reflecting surface, a first transmitting surface, and a second transmitting surface, wherein light rays enter each said objective lens system through the corresponding first transmitting surface and are reflected successively by the first, second, third and fourth reflecting surfaces to exit from each said objective lens system through the corresponding second transmit ting surface in a direction different from a direction in which the light rays are incident on the corresponding first transmitting surface.

134. The binoculars as set forth in claim 124 or 125, wherein at least one of the first transmitting surfaces and the corresponding second reflecting surface are portions of a single surface.

135. The binoculars as set forth in claim 124 or 125, wherein at least one of the second transmitting surfaces and the corresponding third reflecting surface are portions of a single surface.

136. The binoculars as set forth in claim 124 or 125, wherein at least one of the first reflecting surfaces and the corresponding third reflecting surface are portions of a single surface.

137. The binoculars as set forth in claim 124 or 125, wherein at least one of the second reflecting surfaces and the corresponding fourth reflecting surface are portions of a single surface.

138. The binoculars as set forth in claim 124 or 125, wherein at least one of the first transmitting surfaces, the corresponding second reflecting surface, and the corresponding fourth reflecting surface are portions of a single surface.

139. The binoculars as set forth in claim 124 or 125, wherein at least one of the first transmitting surfaces and the corresponding second reflecting surface are portions of a single surface, and wherein at least one of the first reflecting surfaces and the corresponding third reflecting surface are portions of a single surface.

140. The binoculars as set forth in claim 124 or 125, wherein at least one of the first transmitting surfaces and the corresponding second reflecting surface are portions of a single surface, and wherein at least one of the second transmitting surfaces and the corresponding third reflecting surface are portions of a single surface.

141. The binoculars as set forth in claim 124 or 125, wherein at least one of the first reflecting surfaces and the corresponding third reflecting surface are portions of a single surface, and wherein at least one of the second reflecting surfaces and the corresponding fourth reflecting surface are portions of a single surface.

142. The binoculars as set forth in claim 124 or 125, wherein at least one of the second reflecting surfaces and the corresponding fourth reflecting surface are portions of a single surface, and wherein at least one of the second transmitting surfaces and the corresponding third reflecting surface are portions of a single surface.

143. The binoculars as set forth in claim 124 or 125, wherein at least one of the first transmitting surfaces, the corresponding second reflecting surface, and the corresponding fourth reflecting surface are portions of a single surface, and wherein at least one of the second transmitting surfaces and the corresponding third reflecting surface are portions of a single surface.

144. The binoculars as set forth in claim 124 or 125, wherein at least one of the first transmitting surfaces, the corresponding second reflecting surface, and the corresponding fourth reflecting surface are portions of a single surface, and wherein at least one of the first reflecting surfaces and the corresponding third reflecting surface are portions of a single surface.

145. The binoculars as set forth in claim 124 or 125, wherein at least one of the first transmitting surfaces and the corresponding second reflecting surface are portions of a single surface, and wherein at least one of the second transmitting surfaces, the corresponding first reflecting surface, and the corresponding third reflecting surface are portions of a single surface.

146. The binoculars as set forth in claim 124 or 125, wherein at least one of the second reflecting surfaces and the corresponding fourth reflecting surface are portions of a single surface, and wherein at least one of the second transmitting surfaces, the corresponding first reflecting surface, and the corresponding third reflecting surface are portions of a single surface.

147. The binoculars as set forth in claim 124 or 125, wherein at least one of the first transmitting surfaces, the corresponding second reflecting surface, and the corresponding fourth reflecting surface are a same surface, and wherein at lest one of the second transmitting surfaces, the corresponding first reflecting surface, and the corresponding third reflecting surface are a same surface.

125. A pair of binoculars comprising:

a right eye ocular lens system and a left eye ocular lens system, both said ocular lens systems being provided in the binoculars;

said left eye ocular lens system having at least an optical surface for one of transmitting light rays and reflecting light rays, said optical surface having a curved shape, said curved surface having no axis of rotational symmetry into or out of said optical surface, wherein rotationally asymmetric aberrations due to decentration are corrected by the rotationally asymmetric surface, and

said right eye ocular lens system having at least an optical surface for one of transmitting rays and reflecting light rays, said optical surface having a curved shape, said curved surface having no axis of rotational symmetry into or out of said optical surface, wherein rotationally asymmetric aberrations due to decentration are corrected by the rotationally asymmetric surface,

wherein the rotationally asymmetric surface is a plane-symmetric three-dimensional surface having only one plane of symmetry, and

wherein said left eye ocular lens system and said right eye ocular lens system each are integrally formed as a unitary lens structure and comprise at least a first reflecting surface, a second reflecting surface, a third reflecting surface, a fourth reflecting surface, a first transmitting surface, and a second transmitting surface, wherein light rays enter each said ocular lens system through the corresponding first transmitting surface and are reflected successively by the corresponding first, second, third and fourth reflecting surfaces to exit from each said ocular lens system through the corresponding second transmitting surface in a direction different from a direction in which the light rays are incident on the corresponding first transmitting surface.