JP4671758B2 - Optical system - Google Patents

Description

  The present invention relates to an optical system, and in particular, is small and has good resolution, and forms an image having a 360 ° omnidirectional angle of view on an image plane, or an image arranged on the image plane has a 360 ° omnidirectional angle of view. The present invention relates to an optical system suitable for an all-sky camera, an all-sky projector, and the like.

Conventionally, as an optical system that obtains an image of 360 ° omnidirectional (entire circumference) using a reflective optical system, a front group that is rotationally symmetric around a central axis having a reflective surface of one surface, and rotates around the central axis There are known reflection optical systems disclosed in Patent Documents 1 to 3, which are symmetrical and have a rear group having positive power.
JP 60-42728 A Japanese Patent No. 2925573 Japanese Patent No. 3580542

  However, in any of the above conventional examples, the front group that acts to convert a circular beam aerial image at an arbitrary position by receiving a light beam coming from the entire surrounding image toward the central axis rotates around the central axis. Since it consists of only one symmetric reflecting surface, the angle of view in the central axis direction cannot be widened, and the astigmatic difference between the central axis direction and the direction orthogonal thereto is large, and it is not necessarily high resolution. It was.

  The present invention has been made in view of such problems of the prior art, and its purpose is to take an image having an angle of view of 360 ° omnidirectional (all circumferences) or 360 ° omnidirectional (all circumferences). (2) To provide an optical system that is small in size for projecting an image at an angle of view, has little flare light, has a wide angle of view in the vertical direction, and good resolution.

The optical system of the present invention that achieves the above object forms an image having a 360 ° omnidirectional angle of view on an image plane, or projects an image arranged on the image plane onto a 360 ° omnidirectional angle of view. A system,
A front group including one reflecting surface that is rotationally symmetric about the central axis, a rear group that is rotationally symmetric about the central axis and has positive power, and an opening that is coaxially disposed on the central axis.
In the case of an imaging system, the light beam that has entered the front group from a distance passes through the front group and the rear group in this order, as opposed to the order in which the light beam advances in the projection system. imaged at a position deviated from the axis, and a cross section including the center axis, an intermediate image number in a plane including the central ray of orthogonal the optical beam is configured differently with respect to its cross section ,
A light beam incident from one distant direction is reflected and refracted only on one side with respect to the central axis in the front group, intermediately formed once in a cross section including the central axis, and with respect to the cross section including the central axis. An intermediate image is not formed in a plane that is orthogonal and includes the central ray of the light beam, and the aperture forms a conjugate entrance pupil closer to the object side than the reflecting surface in the front group in a cross section including the central axis. It is characterized by.

  In this case, the front group has an angle of view of 90 ° or more in the direction of the central axis, and has a transparent medium that is rotationally symmetric about the central axis, and the transparent medium has one internal reflection surface and two refractive surfaces. In the case of an imaging system, the light beam incident on the front group from a distance passes through the refractive surface of the incident surface and enters the transparent medium. It can be configured such that it enters, is reflected by the inner reflection surface, goes out of the transparent medium through the refracting surface of the exit surface, and forms an image at a position off the central axis of the image surface through the rear group.

  The rear group is preferably composed of a rotationally symmetric coaxial refractive optical system.

When the focal length in the cross section including the central axis of the front group is Fy, and the focal length in the plane including the central ray of the light beam orthogonal to the cross section and incident from a distance is Fx,
−100 <Fx / Fy <−0.01 (4)
It is desirable to satisfy the following conditions.

Further, in the cross section including the central axis, if the optical path length from the entrance pupil position to the aperture position is C, and the optical path length from the entrance pupil position to the entrance surface of the previous group is D, the value in which the light ray direction is positive,
5 <| C / D | (3)
It is desirable to satisfy the following conditions.

Also, when the Pebbar sum of the rear group is p and the focal length is Fb,
−0.5 <p × Fb <−0.01 (1)
It is desirable to satisfy the following conditions.

In the cross section including the central axis, if the optical path length from the entrance pupil position to the reflecting surface is A, and the optical path length from the reflecting surface to the opening is B,
0.05 <A / B <2 (2)
It is desirable to satisfy the following conditions.

Also, the focal length in the cross section including the central axis of the front group is Fy, the focal length in the plane including the central ray of the light beam perpendicular to the cross section and incident from a distance is Fx, and the focal length of the rear group is Fb. and when,
0.05 <Fx / Fb <10 (5)
−10 <Fy / Fb <−0.05 (6)
It is desirable to satisfy at least one of the conditions.

  Further, it is desirable that the reflecting surface has a rotationally symmetric shape formed by rotating an arbitrary-shaped line segment having no symmetrical surface around the central axis.

  Further, it is desirable that the reflecting surface has a rotationally symmetric shape formed by rotating an arbitrary-shaped line segment including an odd-order term around the central axis.

  Further, at least the reflection surface may be cut by a cross section including the central axis, and the angle of view around the central axis may be narrower than 360 °.

  According to the present invention as described above, an image having a field angle of 360 ° omnidirectional (all circumferences) can be obtained with a small size, little flare light, wide vertical angle of view, and good resolving power. An optical system for projecting an image at an angle of view can be obtained.

  The optical system of the present invention will be described below based on examples.

  FIGS. 1 and 6 are cross-sectional views taken along the central axis (rotation symmetry axis) 1 of the optical systems of Examples 1 and 2, which will be described later, and FIGS. The optical system of the present invention will be described with reference to FIGS. 1, 2, 6, and 7, which are plan views showing optical paths. Although the following description will be described as an imaging optical system, it can also be used as a projection optical system that projects an image in all 360 ° azimuths (entire circumference) with the optical path reversed.

  The optical system of the present invention includes a front group 10 that is rotationally symmetric about the central axis 1, a rear group 20 that is rotationally symmetric about the central axis 1, and an aperture (aperture) 5 that is disposed coaxially with the central axis 1. The light beam 2 incident from a distant object forms an image at a position deviating from the central axis 1 of the image plane 30 perpendicular to the central axis 1 through the front group 10 and the rear group 20 in this order.

  The front group 10 includes one reflecting surface 11 that is rotationally symmetric about the central axis 1. In Example 1 of FIG. 1, the front group 10 includes only the reflecting surface 11, and in Example 2 of FIG. 6, the front group 10 is a transparent medium such as a resin having a refractive index greater than 1 that is rotationally symmetric about the central axis 1. And has one inner reflection surface 11 and two transmission surfaces (incidence surface, exit surface) 12 and 13. The rear group 20 is composed of a coaxial refractive optical system such as a lens system having a positive power and rotational symmetry about the central axis 1.

  In such a configuration, when the central axis 1 is the Y axis and the cross section including the central axis 1 (FIGS. 1 and 6) is the YZ plane, the central axis (rotationally symmetric axis) 1 in the front group 10. Therefore, it is easy to avoid interference with the effective diameter of the surface, and the observation angle of view in the direction of the central axis 1 can be increased. When the optical path of the front group 10 is configured only on one side of the central axis 1 in this way, all the surfaces of the front group 10 are in relation to the Y axis (rotation symmetry axis 1) in the XY plane (FIGS. 2 and 7). Since the reflecting surface 11 cannot have positive power in the XY plane, it is impossible to form an image with the front group 10. Therefore, by setting the shape in the YZ plane where the surface shape can be arbitrarily set, an object image (real image) is formed only once in the YZ plane, and at the image plane 30 side from the front group 10. An entrance pupil 6Y is formed by projecting an aperture (aperture) 5 coaxial with the central axis 1 located on the object side.

  By relaying the entrance pupil 6Y to the object side only in the YZ plane, when the front group 10 is composed of the entrance surface 12, the reflection surface 11, and the exit surface 13 (FIG. 6), in the vicinity of the first surface 12 When the front group 10 is configured by only the reflecting surface 11 (FIG. 1), it can be arranged on the object side from the reflecting surface 11, and the effective diameter of the front group 10 itself can be reduced. .

  Further, by arranging to relay the image of the diaphragm 5 to the object side only in the YZ plane, the entrance pupil 6Y can be relayed to the object side from the vicinity of the first surface 12 of the front group 10 or from the reflecting surface 11. This makes it possible to reduce unnecessary light incident on the front group 10 and to observe an image with less flare. That is, when the entrance pupil 6Y in the Y direction is projected in the vicinity of the optical system entrance surface 12 or on the object side from the reflection surface 11, the effective diameter of the entrance direction 12 of the entrance surface 12 of the optical system is reduced in principle even if the field angle is wide. It becomes possible to do.

  Although the entrance pupil 6X in the X direction (FIGS. 2 and 7) spreads out in a circumferential shape, a slit-like flare stop can be arranged in the Y direction, and unnecessary light can be cut by this flare stop. Become.

  Further, in the optical system of the present invention, it is possible to obtain a good aberration state as a whole by correcting the aberration generated in the front group 10 and the aberration generated in the rear group 20 so as to compensate each other.

  In addition, as described above, the role of the front group 10 is to receive a light beam coming from the entire surrounding image toward the rotational symmetry axis 1 and convert it into an annular aerial image at an arbitrary position. The role of the rear group 20 is to project the annular aerial image onto the plane of the image plane 30. Here, the rear group 20 is a projection optical system having a positive power. Further, in order to reduce the size of the rear group 20, it is required to be a projection optical system with a short focal length and a wide angle of view. However, in general, a projection optical system with a short focal length and a wide angle of view often has a negative Petzval sum. In order to correct this, it is necessary to use a negative power lens such as a triplet or Gauss type, which increases the number of components.

  Therefore, in the present invention, it is desirable that the front group 10 has an action of correcting the negative Petzval sum generated in the rear group 20.

  More preferably, in order to complement the astigmatic difference generated in the front group 10, a large astigmatic difference is intentionally generated in the rear group 20, so that aberrations in the entire system are complemented. Corrects aberrations at a good level.

  With the configuration as described above, it is possible to configure a panoramic optical system having a wide angle of view with a small number of components as a whole.

  The Pebbard sum of the rear group 20 of Examples 1 to 3 described later and the focal length of the rear group 20 are as follows.

Example 1 Example 2 Example 3
Petzval sum p 0.011 -0.062 -0.044
Focal length Fb 4.743 4.254 5.086
p × Fb 0.052 -0.264 -0.224
The above-mentioned p × Fb indicates how much the rear group 20 corrects the Petzval sum, and the more it is corrected, the smaller the field curvature of the rear group 20 can be reduced. The system becomes complicated.

−0.5 <p × Fb <−0.01 (1)
If the lower limit of −0.5 of the conditional expression (1) is exceeded, the Petzval sum of the rear group 20 becomes too large to be complementary to the front group 10. If the upper limit of −0.01 is exceeded, the correction of the Petzval sum of the rear group becomes excessive, the configuration of the rear group 20 becomes complicated, and an expensive and large optical system is obtained.

  In the optical system of the present invention, in the cross section including the central axis 1, the optical path length from the entrance pupil 6Y position to the reflecting surface 11 is A, the optical path length from the reflecting surface 11 to the stop 5 position is B, and those The ratio is A / B. A / B defines the conjugate relationship between the entrance pupil 6Y and the stop 5, and when A / B is close to 1, the back projection magnification of the stop 5 onto the entrance pupil 6Y is equal, and the occurrence of pupil aberration is reduced. The flare stop works effectively.

  A, B, and A / B in Examples 1 to 3 described later are as follows.

Example 1 Example 2 Example 3
A 59.962 12.681 25.674
B 65.212 59.350 45.070
A / B 0.919 0.213 0.569
The present invention is characterized in that the entrance pupil 6Y is projected on the object side only within the cross section including the central axis 1, and the pupil aberration of the entrance pupil 6Y that hits the conjugate position with the stop 5 is corrected to some extent. desirable. Thereby, when a flare stop is disposed in the vicinity of the entrance pupil 6Y, harmful light can be surely cut. The following conditions are conditions for correcting this pupil aberration best.

0.05 <A / B <2 (2)
If the lower limit of 0.05 of the conditional expression (2) is exceeded, the entrance pupil 6Y is too close to the reflecting surface 11 with respect to the stop 5, and the occurrence of pupil aberration becomes large. When the upper limit of 2 is exceeded, the entrance pupil 6Y is now too far from the stop 5, and the size of the entrance pupil 6Y becomes too large at the same time as the apparatus becomes large, making it difficult to cut unnecessary light. .

  When the front group 10 has one inner reflection surface 11 and two transmission surfaces (incidence surfaces, exit surfaces) 12 and 13, from the position of the entrance pupil 6Y to the position of the stop 5 in the cross section including the central axis 1. Is C, the optical path length from the entrance pupil 6Y position to the first surface (transmission surface) 12 of the front group 10 is a value D with the ray direction being positive, and the ratio thereof is | C / D |. , | C / D | represents the degree to which the entrance pupil 6Y is disposed in the vicinity of the entrance surface 12 of the front group 10.

  C, D, and | C / D | of Examples 1 to 3 described later are as follows.

Example 1 Example 2 Example 3
C-72.031 70.744
D-0.060 -3.503
｜ C / D ｜-1200.516 20.195
In the present invention, the entrance pupil 6Y is projected on the object side only within the cross section including the central axis 1, and the flare stop that prevents ghosts and the like is effectively provided by arranging the entrance pupil 6Y closer to the entrance surface 12. It becomes possible to arrange. As a result, the incident surface 12 of the optical system can be reduced in the YZ section, and unnecessary light incident on the front group 10 can be effectively prevented, which is effective for fundamental flare countermeasures. . In addition, by arranging the entrance pupil 6Y of the YZ cross section in the vicinity of the entrance surface 11 of the front group 10, the effective surface of the entrance surface 12 of the front group 10 can be reduced in the YZ direction, and reflection is performed. Interference with the surface 11 is eliminated, and a wide angle of view in the YZ section can be achieved. Furthermore, since the effective surface is small, the optical system can be made compact. To that end,
5 <| C / D | (3)
It is desirable to satisfy. If the lower limit of 5 of the conditional expression (3) is exceeded, the entrance pupil 6Y is separated from the optical system first surface 12. The effective diameter of the first surface 12 is increased, the angle of view cannot be taken, and harmful flare light increases. The larger this value is, the more effectively the flare stop for preventing flare can work.

More preferably,
10 <| C / D | (3-1)
It is preferable to satisfy the following conditions.

Furthermore, tracks the center of the angle of view of the principal ray (center ray) 2 ₀ in parallel with a small distance (0.1 mm) apart subordinate rays are a front unit 10 features of the present invention, when emitted from the rear unit 20 When the focal lengths Fx and Fy of the entire optical system are obtained from the angle formed by the dependent ray and the principal ray, with respect to Examples 1 to 3 described later,
Example 1 Example 2 Example 3
Fx 2.105 2.114 1.997
Fy -3.445 -1.073 -1.936
Fx / Fy -0.611 -1.969 -1.031
Fb 4.743 4.254 5.086
Fx / Fb 0.444 0.497 0.393
Fy / Fb -0.726 -0.252 -0.381
It becomes. However, Fb is the focal length of the rear group 20 only. Here, Fy is the focal length of the section including the center axis 1, Fx is the focal length in the plane including the center ray 2 ₀ of the light beam 2 coming from afar perpendicular to its cross section.

In the present invention, since there are cross sections where an intermediate image (real image) of an object is formed and cross sections where no image is formed depending on the cross-sectional direction of the entire group, Fx and Fy of the entire optical system are also different in sign. This is because the focal length of the optical system that forms the intermediate image once is negative in definition. Furthermore, the ratio Fx / Fy of the respective focal lengths is used for aberration correction in each cross section,
−100 <Fx / Fy <−0.01 (4)
It is preferable to satisfy the following conditions.

  When the lower limit of −100 of conditional expression (4) is exceeded, the focal length in the Y direction becomes too short compared to the focal length in the X direction, and aberrations in the Y direction, particularly field curvature and astigmatism, are generated. At the same time, the difference between the inner and outer diameters of the annular image is reduced, and the total resolving power cannot be obtained particularly when the resolving power of the image sensor is limited.

  If the upper limit of −0.01 is exceeded, the focal length in the X direction becomes too short compared to the focal length in the Y direction, and the vertical angle of view cannot be increased.

More preferably,
−10 <Fx / Fy <−0.1 (4-1)
Is preferably satisfied.

Further, with respect to the focal length Fb of the rear group 20,
0.05 <Fx / Fb <10 (5)
−10 <Fy / Fb <−0.05 (6)
It is preferable to satisfy the following conditions.

  These conditional expressions express how much the entire group has an influence on the focal length of the rear group 20, and in the case of 1 or -1, the focal length of the rear group 20 remains as it is in the entire system. Indicates that the focal length is reached.

  The lower limit of 0.05 in conditional expression (5) and the upper limit of -0.05 in conditional expression (6) are compared to the focal length of the entire system when the entire system is set to a certain focal length. This means that the focal length of the rear group 20 becomes longer. Then, the angle of view of the rear group 20 is not required to be so wide, but the pupil diameter becomes large, and particularly correction of chromatic aberration becomes difficult, and at the same time, the entire apparatus (height) becomes large. Further, it becomes difficult to generate large curvature of field, astigmatism and image distortion in the rear group 20, and these perfect corrections in the front group 10 are required.

  Exceeding the upper limit 10 of conditional expression (5) and the lower limit of −10 of conditional expression (6) means that the focal length of the rear group 20 becomes shorter than the focal length of the entire system. Then, since the rear group 20 is required to have a wide angle of view and the focal length becomes too short, the resolving power of the peripheral image of the rear group 20 decreases due to curvature of field, astigmatism, chromatic aberration of magnification, and the like. . As a result, the resolution of the outer peripheral portion of the annular image is deteriorated as the entire optical system.

  More preferably, it is desirable that the conditional expressions (5) and (6) are simultaneously satisfied.

More preferably,
0.1 <Fx / Fb <2 (5-1)
-2 <Fy / Fb <-0.1 (6-1)
It is preferable to satisfy the following conditions.

  Examples 1 to 3 of the optical system according to the present invention will be described below. The configuration parameters of these optical systems will be described later. The configuration parameters of these embodiments are based on the result of tracking the normal ray from the object plane to the image plane 30 through the front group 10 and the rear group 20, as shown in FIG.

  In the forward ray tracing, for example, as shown in FIG. 1, the coordinate system uses the position where the entrance pupil 6Y is projected on the rotational symmetry axis (center axis) 1 as the origin of the eccentric optical surface of the eccentric optical system, and the rotational symmetry axis (center). 1) A direction away from the image plane 30 on the axis 1 is defined as a positive Y-axis direction, and a plane in FIG. 1 is defined as a YZ plane. 1 is the Z axis positive direction, and the Y axis, the Z axis, and the axis constituting the right-handed orthogonal coordinate system are the X axis positive direction. .

  For the decentered surface, the amount of decentering from the center of the origin of the optical system in the coordinate system in which the surface is defined (X-axis direction, Y-axis direction, and Z-axis direction are X, Y, and Z, respectively) and the optical system The inclination angles (α, β, γ (°), respectively) of the coordinate system defining each surface centered on the X axis, Y axis, and Z axis of the coordinate system defined at the origin are given. In this case, positive α and β mean counterclockwise rotation with respect to the positive direction of each axis, and positive γ means clockwise rotation with respect to the positive direction of the Z axis. Note that the α, β, and γ rotations of the central axis of the surface are performed by rotating the coordinate system defining each surface counterclockwise around the X axis of the coordinate system defined at the origin of the optical system. Then rotate it around the Y axis of the new rotated coordinate system by β and then rotate it around the Z axis of another rotated new coordinate system by γ. It is.

  Further, among the optical action surfaces constituting the optical system of each embodiment, when a specific surface and a subsequent surface constitute a coaxial optical system, a surface interval is given, in addition, the curvature radius of the surface, The refractive index and Abbe number of the medium are given according to conventional methods.

  It should be noted that a term relating to an aspheric surface for which no data is described in the constituent parameters described later is zero. The refractive index and the Abbe number are shown for the d-line (wavelength 587.56 nm). The unit of length is mm. The eccentricity of each surface is expressed by the amount of eccentricity from the position where the entrance pupil 6Y is projected onto the rotational symmetry axis (center axis) 1 as described above.

  The extended rotation free-form surface is a rotationally symmetric surface given by the following definition.

  First, the following curve (b) passing through the origin on the YZ coordinate plane is determined.

^{Z = (Y 2 / RY)} / [1+ {1- (C 1 +1) Y 2 / RY 2} 1/2]
C ₂ Y + C ₃ Y ² + C ₄ Y ³ + C ₅ Y ⁴ + C ₆ Y ⁵ + C ₇ Y ⁶
+ ··· + C ₂₁ Y ²⁰ + ··· + C _{n + 1} Y ⁿ + ····
... (b)
Next, a curve F (Y) obtained by rotating the curve (b) in the positive direction of the X-axis and turning it counterclockwise to be positive is determined. This curve F (Y) also passes through the origin on the YZ coordinate plane.

  The curve F (Y) is translated in the positive Z direction by a distance R (or negative Z direction if negative), and then the rotationally symmetric surface formed by rotating the translated curve around the Y axis is expanded and rotated. Let it be a free-form surface.

  As a result, the extended rotation free-form surface becomes a free-form surface (free-form curve) in the YZ plane and a circle with a radius | R | in the XZ plane.

  From this definition, the Y-axis becomes the axis of the extended rotation free-form surface (rotation symmetry axis).

Where RY is the radius of curvature of the spherical term in the YZ section, C ₁ is the conic constant, C ₂ , C ₃ , C ₄ , C ₅ . Aspheric coefficient.

  In the optical system of the present invention, at least the reflecting surface 11 of the front group 10 is such an extended rotation free-form surface, and has at least an odd-order term and a symmetric surface when expressed by a polynomial in the YZ section. It is desirable to have a rotationally symmetric shape formed by rotating a line segment having an arbitrary shape around the central axis 1. By providing at least the reflecting surface 11 with such a surface shape, it is possible to provide an optical system with good resolving power by correcting decentration aberrations that cannot be avoided in the reflecting optical system, and reducing the size of the optical system. It becomes possible.

  A sectional view taken along the central axis (rotation symmetry axis) 1 of the optical system of Example 1 is shown in FIG. 1, and a plan view showing an optical path in the optical system is shown in FIG. Further, a ray diagram obtained by reverse tracking of the rear group 20 is shown in FIG.

  The optical system of this embodiment includes a front group 10 that is rotationally symmetric about the central axis 1, a rear group 20 that is rotationally symmetric about the central axis 1, and an aperture 5 that is disposed coaxially with the central axis 1. The light beam 2 incident from a distant object forms an image at a position deviating from the central axis 1 of the image plane 30 perpendicular to the central axis 1 through the front group 10 and the rear group 20 in this order. When set to vertical (vertical direction), for example, an image having an angle of view of 360 ° omnidirectional (entire circumference), with the zenith direction facing the center direction of the image and the horizon being an outer circle These images are formed on the image plane 30.

  The front group 10 includes one reflecting surface 11 that is rotationally symmetric about the central axis 1. The rear group 20 includes a lens system including three lenses including five lenses L1 to L5.

  The front group 10 includes a reflecting surface 11 on which a light beam 2 enters from a distant object, and includes an extended rotation free-form surface. However, the conic constant is zero. The lens system constituting the rear group 20 includes, in order from the front group 10 side, a negative meniscus lens L1 having a concave surface facing the front group 10, and a negative meniscus lens having a concave surface facing the biconvex positive lens L2 and the front group 10 side. It consists of a cemented lens of L3 and a cemented lens of a biconvex positive lens L4 and a biconcave negative lens L5.

  When the central axis 1 is oriented in the vertical direction and the optical system is oriented toward the zenith, the central luminous flux 2 incident from a far distance in the horizontal direction is incident on one side with respect to the central axis 1 of the reflecting surface 11 of the front group 10 and is below. And is incident on the rear group 20 through the opening 5 and forms an image at a predetermined position in the radial direction away from the central axis 1 of the image plane 30.

  In the optical system of this embodiment, an aperture (aperture) 5 positioned between the front group 10 and the rear group 20 is projected on the object side by the reflecting surface 11 and the entrance pupil 6Y in the cross-sectional direction including the central axis 1 is reflected on the reflecting surface. 11 is formed in front.

In the optical system of this embodiment, the light fluxes 2, 3U, 3L incident from a distance through the entrance pupil 6Y (the light flux 3U is a light flux incident from the far sky side, 3L is the light flux incident from the far ground side). in the section including the center axis 1 (FIG. 1), it forms an image at a position 4Y between the stop 5 and the reflecting surface 11, also the center ray 2 ₀ of the light beam 2 perpendicular to the plane including the center axis 1 A real image is not formed in the plane including the plane (FIG. 2). 2 indicates the sagittal image plane formed by the front group 10. This sagittal image plane is formed closer to the object side than the reflection plane 11 as a virtual image after exiting the front group 10 because the reflection plane 11 acts as a convex reflection plane.

The specification of this Example 1 is
Horizontal field of view 360 °
Vertical angle of view 20 °
Entrance pupil diameter 0.8mm
Image size φ5.08 to φ2.36mm
It is.

  FIG. 3 is a ray diagram by back ray tracing of the rear group 20, and a broken line is a tangential image plane in back ray tracing from the image plane 30 of the rear group 20.

  In this embodiment, in order to reduce the load on the front and rear groups, the curvature of field that occurs in the front and rear groups is made up for each other.

  FIG. 4 shows the lateral aberration of the entire optical system of this example. In this lateral aberration diagram, the angle shown in the center indicates the vertical angle of view, and the lateral aberration in the Y direction (meridional direction) and X direction (sagittal direction) at that angle of view. same as below.

  FIG. 5 is a diagram showing the distortion in the vertical direction of this embodiment, and the curve connected with ▪ indicates the image height (from the central axis 1) on the image plane 30 with respect to the vertical incidence angle of view of the optical system of the first embodiment. It is the graph which plotted the image height of the radial direction. A thick solid line represents a case where the image height is proportional to the incident angle of view (in the case of IH∝f · θ. Here, IH: image height, f: focal length, θ: angle of view).

  A sectional view taken along the central axis (rotation symmetry axis) 1 of the optical system of Example 2 is shown in FIG. 6, and a plan view showing an optical path in the optical system is shown in FIG. Further, a ray diagram obtained by reverse tracking of the rear group 20 is shown in FIG.

  The optical system of this embodiment includes a front group 10 that is rotationally symmetric about the central axis 1, a rear group 20 that is rotationally symmetric about the central axis 1, and an aperture 5 that is disposed coaxially with the central axis 1. The light beam 2 incident from a distant object forms an image at a position deviating from the central axis 1 of the image plane 30 perpendicular to the central axis 1 through the front group 10 and the rear group 20 in this order. When set to vertical (vertical direction), for example, an image having an angle of view of 360 ° omnidirectional (entire circumference), with the zenith direction facing the center direction of the image and the horizon being an outer circle These images are formed on the image plane 30.

  The front group 10 is made of a transparent medium such as a resin having a refractive index that is rotationally symmetric around the central axis 1 and has one internal reflection surface 11 and two transmission surfaces 12 and 13. The inner reflection surface 11 and the transmission surfaces 12 and 13 are also rotationally symmetric around the central axis 1. The rear group 20 includes a lens system including three lenses including six lenses L1 to L6.

  The transparent medium of the front group 10 is located on the same side as the first transmission surface 12 with respect to the central axis 1 and the first transmission surface 12 on which the luminous flux 2 from a distance is incident, and is incident from the first transmission surface 12. The reflective surface 12 on which the luminous flux is incident is also located on the same side as the first transmission surface 12 with respect to the central axis 1, faces the rear group 20, and the luminous flux reflected by the reflective surface 11 enters. 2 transmissive surfaces 13, both of which are extended rotation free-form surfaces. However, the conic constant is zero.

  The lens system constituting the rear group 20 includes, in order from the front group 10 side, a cemented lens of a biconcave negative lens L1 and a biconvex positive lens L2, and a negative meniscus with a concave surface facing the biconvex positive lens L3 and the front group 10 side. The lens includes a cemented lens of a lens L4, a biconvex positive lens L5, and a cemented lens of a negative meniscus lens L6 having a concave surface facing the front group 10 side.

  When the central axis 1 is oriented in the vertical direction, the central light beam 2 incident from a distance in the horizontal direction is refracted by the first transmission surface 12 of the incident surface and enters the transparent medium of the front group 10 and is incident on the reflection surface 11. Then, the light beam reflected to the rear group 20 side is refracted by the second transmission surface 13, exits from the transparent medium of the front group 10, enters the rear group 20 through the opening 5, and is centered on the image surface 30. The image is formed at a predetermined position in the radial direction off the axis 1.

  In the optical system of this embodiment, an aperture (aperture) 5 positioned between the front group 10 and the rear group 20 is projected on the object side, and the entrance pupil 6Y in the cross-sectional direction including the central axis 1 is positioned near the first transmission surface 12. Is formed.

In the optical system of this embodiment, the light fluxes 2, 3U, 3L incident from a distance through the entrance pupil 6Y (the light flux 3U is a light flux incident from the far sky side, 3L is the light flux incident from the far ground side). In the cross section including the central axis 1 (FIG. 6), an image is formed once at a position 4Y between the reflective surface 11 and the second transmission surface 13 near the reflective surface 11 and is orthogonal to the plane including the central axis 1. without forming the intermediate real image is in the plane (Figure 7) containing the center ray 2 ₀ of the light beam perilla. 7 indicates a sagittal image plane formed by the front group 10. This sagittal image surface is formed as a virtual image between the reflecting surface 11 and the second transmitting surface 13 because the reflecting surface 11 acts as a convex reflecting surface.

The specification of Example 2 is
Horizontal field of view 360 °
Vertical angle of view 100 °
Entrance pupil diameter 0.4mm
Image size φ5.71-φ1.98mm
It is.

  FIG. 8 is a ray diagram by back ray tracing of the rear group 20, and a broken line is a tangential image plane in back ray tracing from the image plane 30 of the rear group 20. FIG. 9 shows the lateral aberration of the entire optical system of this example. FIG. 10 is a diagram showing the distortion in the vertical direction of this embodiment, and the meaning of the curved line connected with ▪ and the thick solid line is the same as FIG.

  As shown in FIG. 8, the rear group 20 of the present embodiment causes the curvature of field to largely occur on the convex surface with respect to the traveling direction of the light beam in reverse ray tracing, thereby canceling out aberrations with the front group 10. While having an angle of view of °, the RMS of the point image (spot) has an excellent aberration performance of 13 μm.

  FIG. 11 is a sectional view taken along the central axis (rotation symmetry axis) 1 of the optical system of Example 3, and FIG. 12 is a plan view showing an optical path in the optical system. In addition, a ray diagram obtained by reverse tracking of the rear group 20 is shown in FIG.

  The optical system of this embodiment includes a front group 10 that is rotationally symmetric about the central axis 1, a rear group 20 that is rotationally symmetric about the central axis 1, and an aperture 5 that is disposed coaxially with the central axis 1. The light beam 2 incident from a distant object forms an image at a position deviating from the central axis 1 of the image plane 30 perpendicular to the central axis 1 through the front group 10 and the rear group 20 in this order. When set to vertical (vertical direction), for example, an image having an angle of view of 360 ° omnidirectional (entire circumference), with the zenith direction facing the center direction of the image and the horizon being an outer circle These images are formed on the image plane 30.

  The front group 10 is made of a transparent medium such as a resin having a refractive index that is rotationally symmetric around the central axis 1 and has one internal reflection surface 11 and two transmission surfaces 12 and 13. The inner reflection surface 11 and the transmission surfaces 12 and 13 are also rotationally symmetric around the central axis 1. The rear group 20 includes a lens system including three lenses including six lenses L1 to L5.

  The transparent medium of the front group 10 is located on the same side as the first transmission surface 12 with respect to the central axis 1 and the first transmission surface 12 on which the luminous flux 2 from a distance is incident, and is incident from the first transmission surface 12. The reflective surface 12 on which the luminous flux is incident is also located on the same side as the first transmission surface 12 with respect to the central axis 1, faces the rear group 20, and the luminous flux reflected by the reflective surface 11 enters. 2 transmissive surfaces 13, both of which are extended rotation free-form surfaces. However, the conic constant is zero.

  The lens system constituting the rear group 20 includes, in order from the front group 10 side, a negative meniscus lens L1 having a concave surface facing the front group 10, and a negative meniscus lens having a concave surface facing the biconvex positive lens L2 and the front group 10 side. It consists of a cemented lens of L3, a biconvex positive lens L5, and a cemented lens of a negative meniscus lens L6 with a concave surface facing the front group 10 side.

  When the central axis 1 is oriented in the vertical direction, the central light beam 2 incident from a distance in the horizontal direction is refracted by the first transmission surface 12 of the incident surface and enters the transparent medium of the front group 10 and is incident on the reflection surface 11. Then, the light beam reflected to the rear group 20 side is refracted by the second transmission surface 13, exits from the transparent medium of the front group 10, enters the rear group 20 through the opening 5, and is centered on the image surface 30. The image is formed at a predetermined position in the radial direction off the axis 1.

  In the optical system of this embodiment, an aperture (aperture) 5 positioned between the front group 10 and the rear group 20 is projected on the object side, and the entrance pupil 6Y in the cross-sectional direction including the central axis 1 is used as the first transmission surface 12. It is formed in a transparent medium between the reflecting surfaces 11.

In the optical system of this embodiment, the light fluxes 2, 3U, 3L incident from a distance toward the entrance pupil 6Y (the light flux 3U is a light flux incident from a distant sky side, and 3L is a light flux incident from a distant ground side). the, in the section including the center axis 1 (FIG. 11), and 1 Kaiyuizo the reflecting surface 11 near the position 4Y, also perpendicular to the plane including the center axis 1 includes the center ray 2 ₀ of the light beam 2 An intermediate real image is not formed in the plane (FIG. 12). The broken line in FIG. 12 indicates the sagittal image plane formed by the front group 10. This sagittal image surface is formed as a virtual image between the reflecting surface 11 and the second transmitting surface 13 because the reflecting surface 11 acts as a convex reflecting surface.

The specification of this Example 3 is
Horizontal field of view 360 °
Vertical angle of view 57.32 °
Entrance pupil diameter 0.8mm
Image size φ5.91-φ2.08mm
It is.

  FIG. 13 is a ray diagram by back ray tracing of the rear group 20, and a broken line is a tangential image plane in back ray tracing from the image plane 30 of the rear group 20. FIG. 14 shows the lateral aberration of the entire optical system of this example.

FIG. 15 is a diagram showing the distortion in the vertical direction of this embodiment, and the meaning of the curved line connected with ▪ and the thick solid line is the same as FIG. In this embodiment, since the vertical angle of view is narrow (40 °) and the odd-order term (C ₄ ) is used for the reflecting surface 11 and the transmitting surface 13, the distortion in the vertical direction is very good.

  In this embodiment, the horizontal circumferential angle of view is an image point on the circumference of φ4 mm. Then, the circumference is 4 × π, and the image height in the circumferential direction per horizontal field angle of 1 ° is (0.035 mm / 1 °). On the other hand, the image angle in the vertical direction is 2 mmφ from the inner diameter of the image and the outer diameter is 6 mmφ, and the image height is 2 mm. When the vertical angle of view is about 57.1 °, the image height in the vertical direction is (0.035 mm / 1 °). Thus, it is possible to capture an image having the same resolution in the horizontal direction and the vertical and horizontal directions.

  The configuration parameters of Examples 1 to 3 are shown below. In the table below, “ERFS” indicates an extended rotation free-form surface. “IDL” indicates an ideal lens, and “RE” indicates a reflecting surface.

Example 1
Surface number Curvature radius Surface spacing Eccentricity Refractive index Abbe number Object surface ∞ ∞
1 ∞ (entrance pupil plane) Eccentricity (1)
2 ERFS [1] (RE) Eccentricity (2)
3 ∞ (aperture) Eccentricity (3)
4 1.86 Eccentricity (4) 1.7440 44.8
5 2.90 Eccentricity (5)
6 -60.97 Eccentricity (6) 1.6204 60.3
7 3.30 Eccentricity (7) 1.7552 27.6
8 7.01 Eccentric (8)
9 -6.21 Eccentricity (9) 1.7440 44.8
10 7.31 Eccentricity (10) 1.7355 28.4
11 -8.16 Eccentricity (11)
Image plane ∞ Eccentricity (12)
ERFS [1]
RY ∞
θ 55.39
R -24.09
C ₃ -4.1501 × 10 ^-3
C ₄ 2.9641 × 10 ^-6
C ₅ -2.9541 × 10 ^-7
Eccentricity (1)
X 0.00 Y 0.00 Z -89.61
α 0.00 β 0.00 γ 0.00
Eccentric (2)
X 0.00 Y -3.61 Z 0.00
α 0.00 β 0.00 γ 0.00
Eccentricity (3)
X 0.00 Y -58.07 Z 0.00
α 90.00 β 0.00 γ 0.00
Eccentricity (4)
X 0.00 Y -59.23 Z 0.00
α 90.00 β 0.00 γ 0.00
Eccentricity (5)
X 0.00 Y -61.23 Z 0.00
α 90.00 β 0.00 γ 0.00
Eccentricity (6)
X 0.00 Y -61.33 Z 0.00
α 90.00 β 0.00 γ 0.00
Eccentricity (7)
X 0.00 Y -64.83 Z 0.00
α 90.00 β 0.00 γ 0.00
Eccentricity (8)
X 0.00 Y -65.83 Z 0.00
α 90.00 β 0.00 γ 0.00
Eccentric (9)
X 0.00 Y -65.93 Z 0.00
α 90.00 β 0.00 γ 0.00
Eccentric (10)
X 0.00 Y -69.93 Z 0.00
α 90.00 β 0.00 γ 0.00
Eccentric (11)
X 0.00 Y -70.93 Z 0.00
α 90.00 β 0.00 γ 0.00
Eccentric (12)
X 0.00 Y -74.69 Z 0.00
α 90.00 β 0.00 γ 0.00.

Example 2
Surface number Curvature radius Surface spacing Eccentricity Refractive index Abbe number Object surface ∞ ∞
1 ∞ (entrance pupil plane) Eccentricity (1)
2 ERFS [1] Eccentricity (2) 1.8830 40.7
3 ERFS [2] (RE) Eccentricity (3) 1.8830 40.7
4 ERFS [3] Eccentricity (4)
5 ∞ (aperture) Eccentricity (5)
6 2.50 Eccentricity (6) 1.7217 38.1
7 -8.49 Eccentricity (7) 1.7440 44.8
8 3.54 Eccentricity (8)
9 -11.38 Eccentricity (9) 1.6234 59.7
10 3.51 Eccentricity (10) 1.7552 27.6
11 17.02 Eccentricity (11)
12 -6.56 Eccentricity (12) 1.6204 60.3
13 9.26 Eccentricity (13) 1.6463 33.9
14 73.38 Eccentricity (14)
Image plane ∞ Eccentricity (15)
ERFS [1]
RY ∞
θ 17.42
R -28.35
C ₃ 4.0230 × 10 ^-2
ERFS [2]
RY ∞
θ 67.71
R -21.73
C ₃ -1.6438 × 10 ^-2
C ₄ -1.2092 × 10 ^-3
C ₅ -3.2942 × 10 ^-5
ERFS [3]
RY ∞
θ 134.49
R -7.61
C ₃ 4.8925 × 10 ^-2
C ₄ 1.2565 × 10 ^-3
C ₅ 7.8262 × 10 ^-5
Eccentricity (1)
X 0.00 Y 0.00 Z -28.41
α 0.00 β 0.00 γ 0.00
Eccentric (2)
X 0.00 Y 0.00 Z 0.00
α 0.00 β 0.00 γ 0.00
Eccentricity (3)
X 0.00 Y 0.96 Z 0.00
α 0.00 β 0.00 γ 0.00
Eccentricity (4)
X 0.00 Y -17.69 Z 0.00
α 0.00 β 0.00 γ 0.00
Eccentricity (5)
X 0.00 Y -30.77 Z 0.00
α 90.00 β 0.00 γ 0.00
Eccentricity (6)
X 0.00 Y -30.88 Z 0.00
α 90.00 β 0.00 γ 0.00
Eccentricity (7)
X 0.00 Y -31.88 Z 0.00
α 90.00 β 0.00 γ 0.00
Eccentricity (8)
X 0.00 Y -33.88 Z 0.00
α 90.00 β 0.00 γ 0.00
Eccentric (9)
X 0.00 Y -33.98 Z 0.00
α 90.00 β 0.00 γ 0.00
Eccentric (10)
X 0.00 Y -37.48 Z 0.00
α 90.00 β 0.00 γ 0.00
Eccentric (11)
X 0.00 Y -38.48 Z 0.00
α 90.00 β 0.00 γ 0.00
Eccentric (12)
X 0.00 Y -38.58 Z 0.00
α 90.00 β 0.00 γ 0.00
Eccentric (13)
X 0.00 Y -41.58 Z 0.00
α 90.00 β 0.00 γ 0.00
Eccentric (14)
X 0.00 Y -42.58 Z 0.00
α 90.00 β 0.00 γ 0.00
Eccentric (15)
X 0.00 Y -46.09 Z 0.00
α 90.00 β 0.00 γ 0.00.

Example 3
Surface number Curvature radius Surface spacing Eccentricity Refractive index Abbe number Object surface ∞ ∞
1 ∞ (entrance pupil plane) Eccentricity (1)
2 ERFS [1] Eccentricity (2) 1.7552 27.6
3 ERFS [2] (RE) Eccentricity (3) 1.7552 27.6
4 ERFS [3] Eccentricity (4)
5 ∞ (aperture) Eccentricity (5)
6 2.46 Eccentricity (6) 1.7440 44.8
7 3.52 Eccentricity (7)
8 -82.62 Eccentricity (8) 1.6204 60.3
9 3.61 Eccentricity (9) 1.7552 27.6
10 7.69 Eccentricity (10)
11 -8.65 Eccentricity (11) 1.7352 45.5
12 7.92 Eccentricity (12) 1.7552 27.6
13 277.65 Eccentric (13)
Image plane ∞ Eccentricity (14)
ERFS [1]
RY ∞
θ 48.48
R -32.16
C ₃ 4.8053 × 10 ^-2
ERFS [2]
RY ∞
θ 76.65
R -16.96
C ₃ -1.1588 × 10 ^-2
C ₄ -3.0113 × 10 ^-4
C ₅ -1.4551 × 10 ^-6
ERFS [3]
RY ∞
θ 149.74
R -7.40
C ₃ 3.5918 × 10 ^-2
C ₄ 2.3957 × 10 ^-3
C ₅ 1.2774 × 10 ^-4
Eccentricity (1)
X 0.00 Y 0.00 Z -28.66
α 0.00 β 0.00 γ 0.00
Eccentric (2)
X 0.00 Y 0.00 Z 0.00
α 0.00 β 0.00 γ 0.00
Eccentricity (3)
X 0.00 Y 6.56 Z 0.00
α 0.00 β 0.00 γ 0.00
Eccentricity (4)
X 0.00 Y -4.85 Z 0.00
α 0.00 β 0.00 γ 0.00
Eccentricity (5)
X 0.00 Y -22.18 Z 0.00
α 90.00 β 0.00 γ 0.00
Eccentricity (6)
X 0.00 Y -22.93 Z 0.00
α 90.00 β 0.00 γ 0.00
Eccentricity (7)
X 0.00 Y -24.93 Z 0.00
α 90.00 β 0.00 γ 0.00
Eccentricity (8)
X 0.00 Y -25.03 Z 0.00
α 90.00 β 0.00 γ 0.00
Eccentric (9)
X 0.00 Y -28.53 Z 0.00
α 90.00 β 0.00 γ 0.00
Eccentric (10)
X 0.00 Y -29.53 Z 0.00
α 90.00 β 0.00 γ 0.00
Eccentric (11)
X 0.00 Y -29.63 Z 0.00
α 90.00 β 0.00 γ 0.00
Eccentric (12)
X 0.00 Y -33.63 Z 0.00
α 90.00 β 0.00 γ 0.00
Eccentric (13)
X 0.00 Y -34.63 Z 0.00
α 90.00 β 0.00 γ 0.00
Eccentric (14)
X 0.00 Y -39.76 Z 0.00
α 90.00 β 0.00 γ 0.00.

  In the first and second embodiments, the opening 5 is arranged coaxially with the central axis 1 between the front group 10 and the rear group 20, and the opening 5 is projected back to the object side in a plane including the central axis 1. Thus, the entrance pupil 6Y in the plane including the central axis 1 is formed in front of the reflecting surface 11 (Example 1) or in the vicinity of the entrance surface 12, but instead of the opening 5, FIG. As shown in a sectional view of only one side including the central axis 1 of the modified examples of Embodiments 1 and 2 in FIG. 17, a cylindrical slit or an annular slit 15 is positioned coaxially with the central axis 1 at the position of the entrance pupil 6Y. You may make it arrange | position to. In that case, the slit 15 itself acts as a front diaphragm to form the entrance pupil 6Y.

  Further, in the case where a transparent medium having an inner reflection surface 11 and transmission surfaces 12 and 13 is used as the front group 10 as in the second and third embodiments, the centers of the second and third embodiments are shown in FIGS. 18 and 19, respectively. As shown in the sectional view including the axis 1, apart from the opening 5 that forms the entrance pupil 6Y, a flare composed of a cylindrical slit or a ring-shaped slit that is rotationally symmetric about the central axis 1 in the vicinity of the entrance surface 12. It is desirable to arrange the diaphragm 16. Note that the flare stop 16 and the slit 15 forming the entrance pupil 6Y may be combined (Example 2).

  Further, in the optical system of the above embodiment, a Y toric lens is added to the object side of the front group 10 and the Y toric lens is also a lens configured with a rotationally symmetric surface with respect to the Y axis (center axis 1). The toric lens does not have power in the X direction, while it has negative power in the Y direction (such as in the cross section of FIG. 1). It becomes possible to take a large corner. More preferably, the toric lens has a negative meniscus lens shape with a convex surface facing the object side in the YZ section, thereby minimizing the occurrence of image distortion and enabling good aberration correction. It becomes.

  Furthermore, the object side of the front group 10 is not limited to one Y toric lens having a negative meniscus lens shape in cross section, and is composed of two or three meniscus lenses, thereby reducing image distortion. Is possible. In addition to the lens, it is also easy to image or observe an arbitrary direction by reflecting and refracting the light beam with a reflection surface or prism that is rotationally symmetric with respect to the central axis 1.

  Further, in the above embodiment, the distortion in the vertical direction is intended to be close to the f · θ characteristic (IH ・ f · θ) (particularly in the third embodiment), but this is changed to the f · tan θ characteristic (IH∝). In order to be close to (f · tan θ), correction may be performed using a higher-order odd-order term on the reflecting surface 11 in particular.

  Further, in the above embodiment, the reflecting surface and the refracting surface of the front group 10 are formed by rotating line segments of arbitrary shapes around the rotational symmetry axis 1 and do not have a top on the rotational symmetry axis 1. Although it is composed of an extended rotation free-form surface, it can be easily replaced with an arbitrary curved surface.

  In addition, the optical system of the present invention uses an equation that includes an odd-order term in an expression that defines a line segment of an arbitrary shape that forms a rotationally symmetric surface. The pupil aberration is corrected.

  The optical system of the present invention has been described above as an imaging or observation optical system that obtains an image having 360 ° omnidirectional (all circumference) angles of view including the zenith with the central axis (rotation symmetry axis) 1 in the vertical direction. The present invention is not limited to the photographing optical system and the observation optical system, but can also be used as a projection optical system that projects an image on a 360 ° omnidirectional (all circumference) angle of view including the zenith with the optical path reversed. The endoscope can also be used as an all-round observation optical system of an in-tube observation apparatus.

  Below, the usage example of the panorama imaging optical system 31 or the panorama projection optical system 32 is demonstrated as an application example of the optical system of this invention. FIG. 20 is a diagram for illustrating an example in which the panoramic photographing optical system 31 according to the present invention is used as the photographing optical system at the distal end of the endoscope, and FIG. 20 (a) illustrates the present invention at the distal end of the rigid endoscope 41. This is an example in which a panoramic imaging optical system 31 is attached and 360 ° omnidirectional images are taken and observed. FIG. 20B shows a panoramic photographing optical system 31 according to the present invention attached to the tip of the flexible electronic endoscope 42, and the image photographed on the display device 43 is subjected to image processing and corrected to be displayed. This is an example.

  FIG. 21 shows an image processing system in which a plurality of panoramic imaging optical systems 31 according to the present invention are attached to the corners and the top of an automobile 48 as imaging optical systems, and images taken through the panoramic imaging optical systems 31 are mounted on a display device in a vehicle. This is an example in which distortion is corrected and displayed simultaneously.

  In FIG. 22, the panorama projection optical system 32 according to the present invention is used as the projection optical system of the projection device 44, a panorama image is displayed on the display element arranged on the image plane, and is arranged in all directions through the panorama projection optical system 32. This is an example in which a 360 ° omnidirectional image is projected and displayed on the screen 45.

  In FIG. 23, an imaging device 49 using the panoramic imaging optical system 31 according to the present invention is attached to the outside of a building 47, and a projection device 44 using the panoramic projection optical system 32 according to the present invention is disposed indoors. It connects so that the imaged image may be sent to the projection device 44 via the electric wire 46. In such an arrangement, a 360 ° omnidirectional outdoor subject O is photographed by the photographing device 49 via the panoramic photographing optical system 31, and the video signal is sent to the projecting device 44 via the electric wire 46 and arranged on the image plane. In this example, the image is displayed on the display element, and the image O ′ of the subject O is projected and displayed on an indoor wall surface or the like through the panorama projection optical system 32.

It is sectional drawing taken along the central axis of the optical system of Example 1 of this invention. It is a top view which shows the optical path in the optical system of Example 1 of this invention. FIG. 3 is a ray diagram obtained by backward ray tracing of the rear group of Example 1. 2 is a transverse aberration diagram for the whole optical system of Example 1. FIG. FIG. 4 is a diagram illustrating distortion in the vertical direction according to the first embodiment. It is sectional drawing taken along the central axis of the optical system of Example 2 of this invention. It is a top view which shows the optical path in the optical system of Example 2 of this invention. 6 is a ray diagram obtained by back ray tracing of a rear group of Example 2. FIG. FIG. 6 is a transverse aberration diagram for the whole optical system of Example 2. FIG. 6 is a diagram illustrating distortion in the vertical direction according to the second embodiment. It is sectional drawing taken along the central axis of the optical system of Example 3 of this invention. It is a top view which shows the optical path in the optical system of Example 3 of this invention. 10 is a ray diagram obtained by back ray tracing of a rear group of Example 3. FIG. 5 is a lateral aberration diagram for the whole optical system of Example 3. FIG. FIG. 10 is a diagram illustrating distortion in the vertical direction according to the third embodiment. 6 is a cross-sectional view of only one side including a central axis of a modified example of Example 1. FIG. FIG. 6 is a cross-sectional view of only one side including a central axis of a modified example of Example 2. It is sectional drawing taken along the central axis of the optical system of Example 2 which has arrange | positioned the flare stop. It is sectional drawing taken along the central axis of the optical system of Example 3 which has arrange | positioned the flare stop. It is a figure for showing the example which used the panorama imaging | photography optical system by this invention as an imaging | photography optical system of the endoscope front-end | tip. It is a figure for showing the example using the panorama imaging optical system by the present invention as an imaging optical system in each corner and top of a car. It is a figure for showing the example using the panorama projection optical system by this invention as a projection optical system of a projector. It is a figure for showing the example which image | photographs an outdoor to-be-photographed object via the panorama imaging | photography optical system by this invention, and is projected and displayed indoors through the panorama projection optical system by this invention.

Explanation of symbols

1 ... Center axis (axis of rotational symmetry)
2... Central luminous flux incident from a distance 2 ₀ ... Central ray (principal ray) of central luminous flux
3U: a light beam 3L incident from a far sky side: a light beam 4Y incident from a far ground side: an intermediate image forming position 5: an aperture (aperture)
6Y, 6X ... entrance pupil 10 ... front group 11 ... reflecting surface 12, 13 ... transmitting surface (incident surface, exit surface)
DESCRIPTION OF SYMBOLS 15 ... Cylindrical slit or ring-shaped slit 16 ... Flare stop 20 ... Rear group 30 ... Image plane 31 ... Panoramic imaging optical system 32 ... Panoramic projection optical system 41 ... Rigid endoscope 42 ... Soft electronic endoscope 43 ... Display device 44 ... Projection device 45 ... Screen 46 ... Electric wire 47 ... Building 48 ... Car 49 ... Shooting device L1-L6 ... Lens O ... Subject O '... Video

Claims (11)

An optical system that forms an image having an angle of view of 360 ° on an image plane or projects an image arranged on the image plane on an angle of view of 360 °,
A front group including one reflecting surface that is rotationally symmetric about the central axis, a rear group that is rotationally symmetric about the central axis and has positive power, and an opening that is coaxially disposed on the central axis.
In the case of an imaging system, the light beam that has entered the front group from a distance passes through the front group and the rear group in this order, as opposed to the order in which the light beam advances in the projection system. imaged at a position deviated from the axis, and a cross section including the center axis, an intermediate image number in a plane including the central ray of orthogonal the optical beam is configured differently with respect to its cross section ,
A light beam incident from one distant direction is reflected and refracted only on one side with respect to the central axis in the front group, intermediately formed once in a cross section including the central axis, and with respect to the cross section including the central axis. An intermediate image is not formed in a plane that is orthogonal and includes the central ray of the light beam, and the aperture forms a conjugate entrance pupil closer to the object side than the reflecting surface in the front group in a cross section including the central axis. An optical system characterized by The front group has an angle of view of 90 ° or more in the central axis direction, and has a transparent medium that is rotationally symmetric about the central axis, and the transparent medium has one internal reflection surface and two refractive surfaces. Contrary to the order in which light rays travel in the case of an imaging system and in the order of light rays in the case of a projection system, the light beam incident on the front group from a distance enters the transparent medium via the refractive surface of the incident surface. 2. The method according to claim 1, wherein the light is reflected by the inner reflection surface, passes through the refracting surface of the exit surface, exits from the transparent medium, and forms an image at a position deviating from the central axis of the image surface through the rear group. Optical system. 4. The optical system according to claim 1, wherein the rear group includes a rotationally symmetric coaxial refractive optical system. When the focal length in the cross section including the central axis of the front group is Fy, and the focal length in the plane including the central ray of the light beam orthogonal to the cross section and incident from a distance is Fx,
−100 <Fx / Fy <−0.01 (4)
Optical system of any one of claims 1, wherein the condition is satisfied for 3. In the cross section including the central axis, the optical path length from the entrance pupil position to the opening position is C, and the optical path length from the entrance pupil position to the entrance surface of the front group is a value in which the ray direction is positive, D is
5 <| C / D | (3)
Satisfy conditions optics according to any one of claims 2 to 4, wherein the. When the Pebbar sum of the rear group is p and the focal length is Fb,
−0.5 <p × Fb <−0.01 (1)
Satisfy conditions the optical system of any one of claims 1 5, wherein the. In the cross section including the central axis, if the optical path length from the entrance pupil position to the reflecting surface is A, and the optical path length from the reflecting surface to the opening is B,
0.05 <A / B <2 (2)
Satisfy conditions the optical system of any one of claims 1 6, wherein the. The focal length in the cross section including the central axis of the front group is Fy, the focal length in the plane including the central ray of the light beam perpendicular to the cross section and incident from a distance is Fx, and the focal length of the rear group is Fb. and when,
0.05 <Fx / Fb <10 (5)
−10 <Fy / Fb <−0.05 (6)
Optical system of any one of claims 1, wherein 7 to satisfy at least one of the conditions. Optical any one of claims 1 to 8 wherein the reflecting surface is characterized by having a rotationally symmetric shape formed by rotation of a line segment of arbitrary shape having no plane of symmetry around the central axis system. Optical system of any one of claims 1, characterized in that it comprises a rotationally symmetric shape formed by rotation about the center axis of a line segment of any desired shape 9 including the reflecting surface odd order terms . The optical system according to any one of claims 1 to 10 , wherein at least the reflection surface is cut along a cross section including a central axis, and an angle of view around the central axis is configured to be narrower than 360 °.

Images