JP2011007824A - Optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical device, preventing vignetting by an optical system having versatility from infinity to very close range without any increase in outside diameter of a lens.SOLUTION: A camera (an optical device) includes: a positive objective optical system B1; a positive field lens group B2 disposed on the imaging plane side of the objective optical system B1; and a positive relay lens group (B3, M) for re-imaging an optical image imaged by the objective optical system. The field lens group B2 includes: in order from the object side, a positive lens B2a having a convex shape on the object side; and a negative lens B2b having a concave shape on the object side at an air space between them. In the infinite remote state of the object distance, taking entrance pupil plane of the objective optical system B1 as a first plane of the lens, when the distance from the imaging position to the infinite object distance to the paraxial exit pupil position is Ep, the focal distance of the objective optical system is Fo, the distance from the first plane of the relay lens group to the paraxial entrance pupil position is Ip, and the focal distance of the relay lens group is Fm, 12<Ep/Fo<5.5 and 1.2<Ip/Fm are satisfied.

Description

  The present invention relates to an optical device.

  Patent Documents 1 and 2 propose an optical device (imaging device) having a photographic optical system of a two-time imaging method in order to obtain a super wide photographic angle of view without increasing the lens outer diameter.

Japanese Patent Laid-Open No. 08-54561 JP 2005-128286 A

  However, in the embodiments of Patent Documents 1 and 2, since a dedicated two-time imaging system is designed for each camera (imaging device), there is no versatility, and no means for performing close-up shooting is disclosed. .

  An object of the present invention is to provide an optical device that prevents vignetting with a versatile optical system from infinity to very close without increasing the lens outer diameter.

  An optical apparatus according to one aspect of the present invention includes an objective optical system having a positive refractive power, a field lens group having a positive refractive power and disposed on the imaging surface side of the objective optical system, and the objective optical system A positive relay lens group for re-imaging the optical image formed by the step, the field lens group in order from the object side, a positive lens having a convex shape on the object side, and an air gap It is composed of a negative lens having a concave shape on the object side, and the object optical system connects the infinite object distance to the infinite object distance when the entrance pupil plane of the objective optical system is the first surface when the object distance is infinite. If the distance from the image position to the exit pupil position is Ep, the focal length of the objective optical system is Fo, the distance from the first surface of the relay lens group to the entrance pupil position is Ip, and the focal length of the relay lens group is Fm. 12 <Ep / F <And satisfies the 5.5,1.2 <Ip / Fm.

  An optical device according to another aspect of the present invention is an optical device that is mounted on the object side of a photographing optical system of an imaging device and houses an imaging optical system, and an optical image formed by the imaging optical system The imaging optical system re-images, the imaging optical system is an objective optical system having a positive refractive power, and a field lens group having a positive refractive power disposed on the imaging plane side of the objective optical system The field lens group includes, in order from the object side, a positive lens having a convex shape on the object side, and a negative lens having a concave shape on the object side with an air gap in between. To do.

  The present invention can provide an optical device that prevents vignetting with a versatile optical system from infinity to very close without increasing the lens outer diameter.

FIG. 4 is an optical path diagram at the wide-angle end, the middle, and the telephoto end of the zoom position of the photographing optical system of Numerical Example 1. FIG. 6 is an aberration diagram at the wide-angle end of the photographing optical system in the numerical value example 1. 6 is an aberration diagram at an intermediate focal position of the photographing optical system in the numerical value example 1. FIG. FIG. 4 is an aberration diagram at the telephoto end of the photographing optical system in the numerical value example 1. FIG. 6 is an optical path diagram in which the photographing optical system of Numerical Example 1 is set at the telephoto end and the attachment optical system of Numerical Example 2 is arranged on the object side. FIG. 6 is an optical path diagram when focusing on an object at an infinite object distance and a distance of 5 mm from the first lens surface in the optical system shown in FIG. 5. FIG. 6 is an aberration diagram when the object distance is infinite in the optical system shown in FIG. 5. FIG. 6 is an aberration diagram when the object distance is 5 mm from the first lens surface in the optical system shown in FIG. 5. FIG. 6 is an optical path diagram in which the master photographing optical system of Numerical Example 1 is set at the telephoto end, and the attachment optical system of Numerical Example 3 is arranged on the object side. FIG. 10 is an optical path diagram when focusing on an object at an infinite object distance and a distance of 5 mm from the first lens surface in the optical system shown in FIG. 9. FIG. 10 is an aberration diagram when the object distance is infinite in the optical system illustrated in FIG. 9. FIG. 10 is an aberration diagram when the object distance is 5 mm from the first lens surface in the optical system shown in FIG. 9. FIG. 6 is an optical path diagram in which the master photographing optical system of Numerical Example 1 is set at the telephoto end, and the attachment optical system of Numerical Example 4 is arranged on the object side. FIG. 14 is an optical path diagram when focusing on an object at an infinite object distance and a distance of 5 mm from the first lens surface in the optical system shown in FIG. 13. FIG. 14 is an aberration diagram when the object distance is infinite in the optical system shown in FIG. 13. FIG. 14 is an aberration diagram when the object distance is 5 mm from the first lens surface in the optical system shown in FIG. 13. It is an optical path diagram of a foldable optical system in which a reflecting member is arranged in an objective lens group. FIG. 3 is an optical path diagram of a folding optical system configuration in which a reflecting member is disposed between an objective lens group and a field lens group.

  In this embodiment, a new optical system is arranged on the object side using a high-magnification zoom photographing optical system that is inherently provided, such as a digital compact camera (an imaging device or an optical device), and a two-time imaging optical system Is realized. Since it is not necessary to design a dedicated re-imaging system, versatility can be ensured. The new optical system may be an attachment optical system or may be integrated with the re-imaging optical system.

  The twice-imaging optical system of the present embodiment has an objective optical system having a positive refractive power and a positive refractive power disposed in the vicinity of the primary imaging plane position (imaging plane side) by the objective optical system. It has a field lens group and a positive relay lens group that re-images the optical image formed by the objective optical system. As will be described later, the relay lens group includes a part of a new optical system (an auxiliary lens group having a positive refractive power that causes a subject image transmitted through the field lens group to enter the photographing optical system) and the photographing optical system. . That is, the new optical system includes an objective optical system, a field lens group, and an auxiliary lens group.

  Preferably, the objective optical system has a front group having a negative refractive power, which is composed of two negative lenses each having a strong concave surface on the image side in order from the object side, and the curvature of each lens surface. To reduce the occurrence of astigmatism. In addition, the objective optical system includes a rear lens group having a positive refractive power composed of a cemented lens and a convex lens having a positive refractive power as a whole. Have.

  Since the relay lens group has a long entrance pupil, the incident angle of the principal ray of incident light is close to parallel rays. It is desirable that the light deflected by the field lens group is one in which the principal ray approximates a parallel ray state. If this state is lost, vignetting occurs during re-imaging.

  Since the conventional field lens group has a positive single lens or a plurality of positive lenses, it becomes impossible to emit light rays approximated in parallel due to a refracting action as a passing light beam (principal light beam) moves away from the optical axis. Further, the correction means using an aspheric surface causes manufacturing difficulty and cost increase.

  On the other hand, the field lens group of the present embodiment includes a positive lens having a convex shape on the object side in order from the object side and a negative lens having a concave shape on the object side with an air gap in between. After the incident light is deflected by the positive lens, the negative lens on the image side corrects the spherical aberration. As a result, the light emitted from the field lens group becomes near-parallel light, and it is possible to prevent peripheral vignetting of an image that is re-imaged through the relay lens group.

  In this embodiment, the distance from the primary imaging plane position to the exit pupil position with respect to the infinite object distance of the objective optical system in the state where the object distance is infinite when the entrance pupil plane of the objective optical system is the first lens surface. Ep, and Fo is the focal length of the objective optical system. Further, the distance from the first surface of the relay lens group to the entrance pupil position is Ip, and the focal length of the relay lens group is Fm (however, when the relay lens group is a variable power optical system, the telephoto end state is set to the maximum telephoto end state). . At this time, it is preferable that the following conditional expression (formula) is satisfied.

  Formula 1 is a condition for obtaining good optical performance while reducing the size of the objective optical system, and optimally defines the exit pupil distance with the objective optical system as a concentric optical system.

  When the upper limit of Equation 1 is exceeded, the exit pupil distance is shortened, and the angle of light incident on the field lens group becomes tight. In order to set the incident angle to an appropriate exit angle, it is necessary to increase the number of lenses in the field lens group, and astigmatism increases, making it difficult to obtain good image quality.

  When the lower limit of Expression 1 is exceeded, the telecentric action of the objective optical system becomes strong, and the lens diameter of the positive lens component arranged on the image plane side of the objective optical system in order to secure the peripheral light amount increases. Since the peripheral image height rays pass through the lens periphery, coma and astigmatism are greatly generated, and it is difficult to correct them.

  Formula 2 shows the relationship between the focal length of the relay lens group and the entrance pupil distance, and indicates that the relay lens group (the telephoto end state when the relay lens group is a variable power system) has a long exit pupil distance. .

  If the lower limit of Formula 2 is not reached, the entrance pupil distance of the relay lens group is shortened. In order to prevent vignetting on an image formed on an imaging medium such as an imaging device, the outer diameter of a field lens group that guides light to the relay lens optical system must be increased. Will become larger.

  When the new optical system is attached to the object side of the photographic optical system and is an attachment optical system for obtaining a wider angle of view, the optical image formed by the attachment optical system is reconstructed by the photographic optical system. Imaged.

  In the attachment optical system, when the entrance pupil plane of the objective optical system is the first lens surface, the distance from the imaging position to the exit pupil position with respect to the infinite object distance is Ep, and the focal length of the objective optical system is Fo It is preferable that the following conditional expression is satisfied.

  Equation 3 is a condition for obtaining good optical performance while reducing the size of the objective optical system as in Equation 1, and optimally defines the exit pupil distance with the objective optical system as a concentric optical system. Similar to Equation 1, if the numerical value range of Equation 3 is exceeded, a large amount of aberration occurs, making it difficult to correct it and making it difficult to achieve a high-quality optical system.

  Further, it is preferable that the following conditional expression is satisfied, where Ff is the focal length of the field lens group and Fn is the focal length of the negative lens of the field lens group.

  Formula 4 shows the refractive power ratio of the negative lens of the field lens group, and is a condition for emitting light incident from the objective optical system so as not to cause vignetting in the entire image height of the imaging medium. If the numerical value range of Expression 4 is exceeded, it becomes difficult to appropriately deflect the exit angle of each image height by the refraction action of the field lens group, resulting in vignetting.

  When the focal lengths of the object side lens surfaces of the positive lens and negative lens of the field lens group are FR1 and FR2, respectively, it is preferable that the following conditional expressions are satisfied.

  Formula 5 shows the positive and negative refractive power ratio of the field lens group, and is a condition for satisfactorily correcting the aberration generated in the field lens group. If the upper limit of Expression 5 is exceeded, the negative refraction action of the negative lens increases, resulting in an excessive aberration correction action. If the lower limit of Expression 5 is not reached, the aberration correction action is not weak, and vignetting is likely to occur around the image.

  When the radius of curvature of the object side lens surface of the positive lens and the negative lens in the field lens group is RF1 and RF2, respectively, it is preferable that the following conditional expressions are satisfied.

  Formula 6 is the radius of curvature of the most object side lens surface (F1 surface) having positive refractive power in the field lens group and the object side lens surface (F3 surface) having negative refractive power of the negative lens opposite thereto. This is a condition for expressing the ratio and correcting the aberration generated in the field lens group.

  If the upper limit of Expression 6 is exceeded, the curvature of the F3 surface, which is a relatively negative lens surface, on the F1 surface and the F3 surface becomes loose, so that the divergence of light incident on a position away from the optical axis of the field lens unit Is weakened. On the other hand, if the lower limit of Expression 6 is not reached, the curvature of the F1 surface, which is a positive lens surface, becomes tighter relative to the F3 surface, and the convergence action is strengthened. If the numerical value range of Expression 6 is deviated, it becomes difficult to make the principal ray at each image height incident on the field lens group almost parallel to the optical axis over the entire image height range.

  The auxiliary lens group preferably has a doublet in which a positive lens and a negative lens are combined in order to suppress the occurrence of chromatic aberration.

  The photographing optical system includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power. . An iris diaphragm is disposed between the second and third lens groups, and the focusing mechanism moves the fourth lens group in the optical axis direction. For zooming from the wide-angle end to the telephoto end, the first lens unit is moved to the object side, and the air space between the first and second lens units and the third and fourth lens units is widened. This is done by moving each lens group so that the air space between the lens groups becomes narrow. Using an attachment optical system in the vicinity of the telephoto end of the photographing optical system, it is possible to take a vignetting-free image having a super wide angle of view.

  Numerical Example 1 relates to a zoom type imaging optical system used for re-imaging of the attachment optical system of the two-time optical system of the present example. Numerical examples 2 to 4 are attachment optical systems of the two-time optical system proposed in this embodiment.

  In each numerical example, Ri is the i-th lens thickness and air interval in order from the object side, and Ni and νi are the refractive index and Abbe number of the glass of the i-th lens arranged in order from the object side. The aspheric coefficients K, A, B, C, and D give the aspheric shape by the following formula. Where X is the amount of displacement in the direction from the lens apex optical axis, H is the distance from the optical axis, and R is the radius of curvature.

(Numerical example 1)
f = 7.62 to 35.53 Fno = 2.88 to 4.90 2ω = 62.5 ° to 14.8 °
R 1 = 25.758 D 1 = 0.97 N 1 = 1.84666 ν 1 = 23.9
R 2 = 18.488 D 2 = 3.45 N 2 = 1.69680 ν 2 = 55.5
R 3 = 206.825 D 3 = Variable
R 4 = 28.479 D 4 = 0.70 N 3 = 1.88300 ν 3 = 40.8
R 5 = 6.693 D 5 = 3.41
R 6 = -21.529 D 6 = 0.65 N 4 = 1.69680 ν 4 = 55.5
R 7 = 20.660 D 7 = 0.65
R 8 = 14.781 D 8 = 1.94 N 5 = 1.84666 ν 5 = 23.9
R 9 = -990.152 D 9 = variable
R10 = Aperture D10 = 0.86
* R11 = 7.941 D11 = 2.48 N 6 = 1.58313 ν 6 = 59.4
* R12 = -24.952 D12 = 0.22
R13 = 5.513 D13 = 1.72 N7 = 1.48749 ν7 = 70.2
R14 = 10.653 D14 = 0.86 N 8 = 1.84666 ν 8 = 23.9
R15 = 4.204 D15 = Variable
R16 = 10.934 D16 = 2.15 N 9 = 1.58313 ν 9 = 59.4
R17 = 53.668 D17 = variable
R18 = ∞ D18 = 2.15 N10 = 1.51633 ν10 = 64.1
R19 = ∞
\ Focal length 7.62 14.84 35.53
Variable interval \
D 3 0.43 10.61 17.51
D 9 14.03 7.60 2.05
D15 7.75 9.62 20.61
D17 2.15 4.63 2.65
Aspheric coefficient
11th surface: K = -2.51604e-1 A = 0 B = -9.78818e-5 C = 2.38159e-6
D = 2.80967e-7
12th surface: K = 9.03719 A = 0 B = 2.77596e-4 C = 4.38159e-6
D = 3.26865e-7
FIG. 1 is an optical path diagram of a photographing optical system for re-imaging a subject image incident on an attachment optical system shown in Numerical Example 1. The photographing optical system includes a first lens group MB1 having a positive refractive power, a second lens group MB2 having a negative refractive power, a third lens group MB3 having a positive refractive power, and a fourth lens having a positive refractive power. It has a group MB4 and an iris diaphragm SP, and realizes a zoom ratio of about 4.7 times. FIL is a filter such as infrared cut or low-pass, and IP is an image plane. A focusing action is performed by moving the fourth lens group MB4 in the optical axis direction. In the iris diaphragm SP, the distance from the first lens surface to the entrance pupil increases as it goes to the telephoto side.

FIG. 2 is an aberration diagram at the wide-angle end in Numerical Example 1. FIG. 3 is an aberration diagram at the intermediate focal position in the numerical value example 1. FIG. 4 is an aberration diagram for Numerical Example 1 at the telephoto end.
(Numerical example 2)
F = −3.6 Fno = 4.9 when the photographing optical system of Numerical Example 1 is set at the telephoto end.
R 1 = 21.682 D 1 = 1.20 N 1 = 1.77250 ν 1 = 49.6
R 2 = 7.982 D 2 = 1.91
R 3 = 10.616 D 3 = 1.00 N 2 = 1.69680 ν 2 = 55.5
R 4 = 6.422 D 4 = 18.03
R 5 = -28.761 D 5 = 4.48 N 3 = 1.48749 ν 3 = 70.2
R 6 = -5.733 D 6 = 0.80 N 4 = 1.84666 ν 4 = 23.9
R 7 = -9.144 D 7 = 0.20
R 8 = 55.949 D 8 = 3.80 N 5 = 1.48749 ν 5 = 70.2
R 9 = -16.299 D 9 = 30.72
R10 = 17.821 D10 = 6.00 N6 = 1.60311 ν6 = 60.6
R11 = 392.613 D11 = 3.01
R12 = -22.649 D12 = 1.40 N 7 = 1.77250 ν 7 = 49.6
R13 = -59.379 D13 = 74.99
R14 = 134.266 D14 = 2.50 N8 = 1.69680 ν8 = 55.5
R15 = −74.279 D15 = 1.20 N 9 = 1.80518 ν 9 = 25.4
R16 = -90.727
The distance between the R1 surface and the R16 surface when the photographing optical system of Numerical Example 1 is set at the telephoto end is 5 mm.

  FIG. 5 is an optical path diagram in which the attachment optical system of the two-time imaging system of Numerical Example 2 is disposed on the object side of the photographing optical system of Numerical Example 1. M is the photographing optical system of Numerical Example 1, and the reference numerals in the photographing optical system M are the same as those in FIG. A is an attachment optical system of the present embodiment. B1 is an objective optical system having a positive refractive power, and B2 is a field lens group having a positive refractive power disposed in the vicinity of the imaging position of the objective optical system of the objective optical system B1. B3 is a correction lens group having a positive refractive power and for focusing the aerial image formed by the objective optical system B1 on the position of the imaging plane IP of the photographing optical system M. The imaging optical system is formed twice with the attachment optical system A and the photographing optical system M combined. In this case, a combination of the photographing optical system M and the correction lens group B3 is referred to as a relay lens group L.

FIG. 7 is an aberration diagram when the object distance is infinite in the optical system shown in FIG. FIG. 8 is an aberration diagram when the object distance is 5 mm from the first lens surface in the optical system shown in FIG.
(Numerical Example 3)
F = -3.63 Fno = 4.9 when the photographing optical system of Numerical Example 1 is set at the telephoto end.
R 1 = 23.892 D 1 = 1.20 N 1 = 1.77250 ν 1 = 49.6
R 2 = 7.962 D 2 = 4.35
R 3 = 15.142 D 3 = 1.00 N 2 = 1.69680 ν 2 = 55.5
R 4 = 6.637 D 4 = 16.78
R 5 = -260.364 D 5 = 4.70 N 3 = 1.48749 ν 3 = 70.2
R 6 = -5.824 D 6 = 0.80 N 4 = 1.84666 ν 4 = 23.9
R 7 = -9.292 D 7 = 0.20
R 8 = 61.561 D 8 = 2.50 N 5 = 1.48749 ν 5 = 70.2
R 9 = -20.900 D 9 = 31.63
R10 = 18.565 D10 = 6.00 N6 = 1.60311 ν6 = 60.6
R11 = −64.907 D11 = 1.76
R12 = -21.247 D12 = 1.40 N 7 = 1.77250 ν 7 = 49.6
R13 = -77.020 D13 = 65.64
R14 = 48.172 D14 = 1.50 N 8 = 1.84666 ν 8 = 23.9
R15 = 41.837 D15 = 0.81
R16 = 101.926 D16 = 3.00 N9 = 1.69680 ν9 = 55.5
R17 = -70.423
The distance between the R1 surface and the R17 surface when the photographing optical system of Numerical Example 1 is set at the telephoto end is 5 mm.

FIG. 9 is an optical path diagram in which the attachment optical system of the double imaging system of Numerical Example 3 is arranged on the object side of the photographing optical system of Numerical Example 1. Reference numerals in FIG. 9 are the same as those in FIG. FIG. 11 is an aberration diagram when the object distance is infinite in the optical system shown in FIG. FIG. 12 is an aberration diagram when the object distance is 5 mm from the first lens surface in the optical system shown in FIG.
(Numerical example 4)
F = −3.78 Fno = 4.9 when the photographing optical system of Numerical Example 1 is set at the telephoto end.
R 1 = 18.411 D 1 = 1.20 N 1 = 1.77250 ν 1 = 49.6
R 2 = 7.507 D 2 = 1.93
R 3 = 9.912 D 3 = 1.00 N 2 = 1.69680 ν 2 = 55.5
R 4 = 6.341 D 4 = 18.09
R 5 = -45.628 D 5 = 4.66 N 3 = 1.48749 ν 3 = 70.2
R 6 = -6.179 D 6 = 0.80 N 4 = 1.84666 ν 4 = 23.9
R 7 = -9.996 D 7 = 0.20
R 8 = 55.119 D 8 = 3.80 N 5 = 1.48749 ν 5 = 70.2
R 9 = -17.640 D 9 = 31.78
R10 = 18.236 D10 = 7.00 N6 = 1.60311 ν6 = 60.6
R11 = -143.156 D11 = 2.08
R12 = -27.945 D12 = 1.40 N 7 = 1.77250 ν 7 = 49.6
R13 = 875.355 D13 = 76.65
R14 = 143.786 D14 = 2.50 N8 = 1.69680 ν8 = 55.5
R15 = −57.151 D15 = 1.20 N 9 = 1.80518 ν 9 = 25.4
R16 = -85.054
The distance between the R1 surface and the R16 surface when the photographing optical system of Numerical Example 1 is set at the telephoto end is 5 mm.

  FIG. 13 is an optical path diagram in which the attachment optical system of the double imaging system of Numerical Example 4 is arranged on the object side of the photographing optical system of Numerical Example 1. Reference numerals in FIG. 13 are the same as those in FIG. FIG. 15 is an aberration diagram when the object distance is infinite in the optical system shown in FIG. FIG. 16 is an aberration diagram when the object distance is 5 mm from the first lens surface in the optical system shown in FIG.

  5, 9, and 13, the attachment optical system A includes an objective optical system B1, a field lens group B2, and an auxiliary lens group B3 in order from the object side. The objective optical system B1 has a positive refractive power as a whole. The field lens group B2 is disposed in the vicinity of the imaging position (primary imaging plane position) of the objective optical system B1, and has a positive refractive power having a condensing function of the light beam emitted from the objective optical system B1. The auxiliary lens group B3 has a positive refractive power that corrects the focal position in order to re-form the image of the primary imaging surface on the imaging surface position of the imaging optical system M with the light beam emitted from the field lens group B2. . A combination of the auxiliary lens B3 and the photographing optical system M is a relay lens group L having a re-imaging function. The photographing optical system M is set at the telephoto end.

  6, 10, and 14 show a state in which an object at a very close distance 5 mm away from the first lens surface of the optical system in which the object distance is infinite in the optical configurations of FIGS. FIG. Even if a special movable lens group is not disposed in the attachment optical system, it is possible to prevent peripheral vignetting of an image formed on the image sensor by the focus mechanism of the photographing optical system. 6, 10, and 14, the photographing optical system M is set at the telephoto end, and focusing is performed when the object distance is close by moving the fourth lens unit B <b> 4 to the object side.

  In a digital camera (an imaging device or an optical device), an optical device that houses an attachment optical system is replaceably mounted on the object side of a converter attachment that houses a photographing optical system. The converter attachment is an adapter ring that is attached to the digital camera, and is an intermediate member for fixing the optical device that houses the attachment optical system to the digital camera.

  FIG. 17 is an optical path diagram of a folding optical system in which a reflecting member is arranged in the objective lens group. FIG. 18 is an optical path diagram of a folding optical system in which a reflecting member is disposed between the objective lens group and the field lens group. In FIGS. 17 and 18, incident light from the objective optical system is deflected by a reflecting member in order to facilitate low-angle imaging.

  The photographing optical system is a variable magnification optical system having a relatively long entrance pupil position in which the lens unit closest to the object moves during zooming. Further, since the image becomes an inverted image at the time of image formation twice, an electric mechanism for erecting the image is incorporated in the electronic display device on the camera side. Thereby, it is possible to achieve an attachment optical device capable of observing an optical image and an electronic image of the optical device selectively or simultaneously through a common eyepiece optical system at a low cost.

  The optical device can be applied to an imaging device. The imaging device can be applied to imaging a subject.

A Attachment optical system (optical device)
L relay lens group B1 objective optical system B2 field lens group B2a positive lens B2b negative lens B3 auxiliary lens group

Claims (6)

Re-imaging an objective optical system having a positive refractive power, a field lens group having a positive refractive power arranged on the imaging plane side of the objective optical system, and an optical image formed by the objective optical system A positive relay lens group for
The field lens group includes, in order from the object side, a positive lens having a convex shape on the object side and a negative lens having a concave shape on the object side with an air gap in between.
When the object distance is infinitely far and the entrance pupil plane of the objective optical system is the first lens surface, the distance from the imaging position by the objective optical system to the exit pupil position with respect to the infinite object distance is Ep, and the objective optics An optical apparatus satisfying the following conditional expression where Fo is a focal length of the system, Ip is a distance from the first surface to the entrance pupil position, and Fm is a focal length of the relay lens group.
12 <Ep / Fo <5.5
1.2 <Ip / Fm An optical device that is mounted on the object side of the imaging optical system of the imaging device and houses the imaging optical system,
The imaging optical system re-images the optical image formed by the imaging optical system,
The imaging optical system has an objective optical system having a positive refractive power, and a field lens group having a positive refractive power arranged on the imaging surface side of the objective optical system,
The field lens group includes, in order from the object side, a positive lens having a convex shape on the object side and a negative lens having a concave shape on the object side with an air gap in between. When the entrance pupil plane of the objective optical system is the first lens surface, the following conditional expression is satisfied, where Ep is the distance from the imaging position to the exit pupil position with respect to the infinite object distance, and Fo is the focal length of the objective optical system. The optical device according to claim 2.
10 <Ep / Fo <6 3. The optical apparatus according to claim 1, wherein the following conditional expression is satisfied, where Ff is a focal length of the field lens group and Fn is a focal length of the negative lens of the field lens group.
0.35 <| Fn / Ff | <1.0 (Fn <0, Ff> 0) 5. The optical apparatus according to claim 4, wherein the following conditional expressions are satisfied, where the focal lengths of the lens surfaces on the object side of the positive lens and the negative lens in the field lens group are FR1 and FR2, respectively.
1.4 <| FR1 / FR2 | <0.6 (FR1> 0, FR2 <0) The optical apparatus according to claim 5, wherein the following conditional expressions are satisfied when the curvature radii of the lens surfaces on the object side of the positive lens and the negative lens in the field lens group are RF1 and RF2, respectively.
0.5 <| RF1 / RF2 | <1.1 (RF1> 0, RF2 <0)