JP4908853B2 - Optical system - Google Patents

Description

Conventionally, when images are projected onto a 360 ° screen, images from a plurality of projectors are connected on the screen or projected by a wide-angle optical system such as a fisheye lens. As such a prior art, there exists a thing of patent documents 1-7.
US Patent Application Publication No. 2004/8423 Japanese Patent Publication No. 6-85019 US Pat. No. 5,473,474 US Pat. No. 3,283,653 US Pat. No. 3,552,820 US Pat. No. 6,611,282 US Pat. No. 6,597,520

  However, the conventional 360 ° omnidirectional projection and vice versa may be performed by projecting from one or more planes onto a cylindrical surface or spherical surface and vice versa. None of them projected from a conical surface onto a cylindrical surface or spherical surface, or vice versa.

  By the way, as will be apparent from the organic EL display element, future display elements and imaging elements will be display elements or imaging elements that have a rotationally symmetric curved surface such as a cylindrical surface, spherical surface, or conical surface as a display surface or an imaging surface. Is possible enough.

  The present invention has been made in view of such a situation in the prior art, and an object of the present invention is to image an image from all directions on, for example, a cylindrical, spherical, or conical stereoscopic imaging surface, or such a stereoscopic shape. It is an object of the present invention to provide an optical system capable of capturing and projecting a high-definition image with good aberration correction for projecting the display surface in all distant directions.

The optical system of the present invention that achieves the above object is an optical system that forms an image from 360 ° omnidirectional direction on a rotationally symmetric solid image surface, and the image from 360 ° omnidirectional incidence is incident thereon. The first reflecting surface and the second reflecting surface are provided in order, and the first reflecting surface and the second reflecting surface are both rotationally symmetric reflecting surfaces, and the first reflecting surface is An image incident from 360 ° in all directions is reflected to form an intermediate image, and the second reflecting surface reflects the image reflected by the first reflecting surface to form an image on the three-dimensional image surface. It is characterized by that.

In this case, it is desirable that the rotationally symmetrical three-dimensional image surface, the first reflection surface, and the second reflection surface are coaxial.

Further, it is desirable that the entrance pupil of the sagittal section and the exit pupil of the sagittal section are arranged at different positions on the rotational symmetry axis of the first reflecting surface and the second reflecting surface .

The first reflecting surface and the second reflecting surface are rotationally symmetric formed by rotating a line segment having an arbitrary shape having no symmetry plane in a cross section including a rotational symmetry axis around the rotational symmetry axis. It may have a rotationally symmetric shape formed by rotating a line segment having an arbitrary shape including an odd-order term in a cross section including a rotational symmetry axis around the rotational symmetry axis. Of course, it may be spherical.

  The image plane may be the rotationally symmetrical three-dimensional inner surface or the outer surface.

  Further, the object plane and the image plane of the optical system can be reversed and used in a projection optical system.

  According to the present invention described above, the optical system projects an image from all directions on, for example, a cylindrical, conical, or spherical stereoscopic imaging surface, or projects such a stereoscopic display surface in all distant directions. Thus, it is possible to obtain an imaging optical system and a projection optical system capable of capturing and projecting a high-definition image with good aberration correction.

The optical system of the present invention will be described below based on examples. In principle, the description is based on forward ray tracing in the case of an imaging system, and in the order of backward ray tracing in the case of a projection system. In addition, Example 2 and Example 3 are reference examples.

  A simple optical system that captures images of the entire circumference by imaging images from 360 ° omnidirectional distant images onto a cylindrical, conical, spherical, or other rotationally symmetric three-dimensional image surface. It becomes possible to reduce the size. In the case of a conventional transmissive lens, a method can be considered in which a plurality of transmissive lens systems are arranged on the radiation around the cylindrical imaging surface and images are taken from the entire circumference. Unless the position adjustment between the transmission lens systems is strictly performed, captured images are not connected.

  In the case of a projection system, an image displayed on a display element having a rotationally symmetric three-dimensional display surface such as a cylindrical shape, a conical shape, or a spherical shape is projected on the entire 360 ° circumference in the distance. This makes it possible to make the projection system simple and small. In the case of a conventional transmissive lens, a method may be considered in which a plurality of transmissive lens systems are arranged on the radiation around the cylindrical display surface and projected onto the entire circumference. If the positions of the two are not strictly adjusted, the projected images are not connected.

  In addition, since the image plane of each optical system (imaging lens system in the case of an imaging system, projection lens system in the case of a projection system) is a cylindrical surface that is curved only in one direction, it is rotationally asymmetric in order to correct this. It is necessary to use an optical surface, which makes it difficult to manufacture.

  In addition, in an optical system such as the prior art, a 360-degree omnidirectional image is formed as a circular image on a plane (in the case of a projection system, such a display image is formed), so that observation is performed. When doing so, it is necessary to electronically convert such a distorted image into a correct image. In the case of a projection system, it is necessary to electronically convert a correct image into an image distorted in an annular shape.

  Therefore, in the present invention, in order to form an image from the entire 360 ° circumference on the rotationally symmetrical solid image surface as described above, an intermediate image is formed at least once, and 2 The front group and the rear group are each configured to have at least one rotationally symmetric reflecting surface so as to include one group.

  FIG. 1 is a cross-sectional view including a rotation center axis (rotation symmetry axis) 1 of the optical system of Example 1 to be described later, and images from a distant 360 ° omnidirectional direction are rotationally symmetric around the rotation center axis 1. A three-dimensional shape, which is an optical system that forms an image on the image plane 2 of the cylindrical surface in this embodiment. When the 360 ° omnidirectional group is the front group 10 and the group on the image plane 2 side is the rear group 20, the front group The rear group includes at least one reflecting surface 11 and 21 that is rotationally symmetric with the rotational center axis 1 of the image plane 2 as a rotational symmetry axis (the first embodiment has one reflecting surface 11 and 21 respectively). . This optical system is configured to form an intermediate image at least once before forming an image from 360 ° in all directions on the image surface 2 (in the first embodiment, the reflecting surface 11 and the reflecting surface). An intermediate image is formed once at a position 3 between 21.)

  In order to form an image continuous in 360 ° in all directions on a three-dimensional image surface 2 such as a cylindrical surface, the optical surfaces (reflective surfaces and refractive surfaces) constituting the optical system must be rotationally symmetric. However, if the optical system is composed of only refractive optical elements, all refractive surfaces are rotationally symmetric with respect to the rotationally symmetric axis 1, and the sagittal section (the section including the rotational center axis 1 is the meridional section (FIG. 1)). It is very difficult to give the optical system the positive power necessary for image formation on an axial principal ray in the meridional section and a section perpendicular to the meridional section. Therefore, in the present invention, when the 360 ° omnidirectional group is the front group 10 and the group on the image plane 2 side is the rear group 20, the front group 10 and the rear group 20 are rotationally symmetric annular reflecting surfaces 11 respectively. 21 have at least one surface.

  In the prior art, a 360 ° omnidirectional image is formed as a circular image on a plane by a rotationally symmetric optical system, but the front-side optical system on the incident side reaches the center of the image plane. Since the decentration optical system decenters the light beam, large decentration aberration occurs in the front group. In particular, it is very difficult to correct decentration aberrations with respect to the tilt of the object surface, and it is difficult to correct only the front group.

  Therefore, in the present invention, in order to complement the inclination of the object plane, an image is formed on the image plane 2 having a cylindrical shape or the like. Further, in order to satisfactorily correct decentration aberrations that are still undercorrected, one or more intermediate images are formed, and the optical system includes two groups, and at least one surface is provided in each group. In order to achieve good aberration correction, the front group 10 and the rear group 20 complement each other with decentration aberrations. It is a success.

  More preferably, the rotationally symmetric three-dimensional image surface 2 such as a cylindrical surface and the rotationally symmetric reflecting surfaces 11 and 21 are preferably coaxial. With this arrangement, it is possible to capture images from equidistant distances in all 360 ° directions. If the rotational symmetry axes do not match, the object distance will be biased and a high-resolution image cannot be captured.

  Further, the entrance pupil 4s of the sagittal section (in the first embodiment, the entrance pupil 4m of the meridional section and the entrance pupil 4s of the sagittal section exist at the same position) and the exit pupil 5s of the sagittal section are separated on the rotational symmetry axis 1. It is preferable that they are arranged. When an image from 360 ° in all directions is formed on the image plane 2 as in the optical system of the present invention, the light beam formed on the solid image plane 2 is incident on the sagittal section on the rotational symmetry axis 1. As it is emitted from the pupil 4s, it reaches the annular reflecting surface 11 of the front group 10 and is reflected by the reflecting surfaces 11 and 21 of the front group 10 and the rear group 20, and then the exit pupil 5s (rotation symmetry axis) of the sagittal section. The image travels toward the image plane 2 so as to pass through the image plane 2 and is imaged on the image plane 2. At this time, if the entrance pupil 4s of the sagittal section and the exit pupil 5s of the sagittal section are coincident or arranged very close to each other, light rays are vignetted (blocked) on the image plane 2 and an image is formed. I can't.

  More preferably, the reflecting surfaces 11 and 21 have a rotationally symmetric shape formed by rotating an arbitrary-shaped line segment having no symmetry plane in the cross section including the rotation center axis 1 around the rotation symmetry axis 1. Is preferred. With this shape, it is possible to vary the partial radius of curvature up and down in the direction of the rotational symmetry axis 1 of the reflecting surfaces 11 and 21, and it is possible to correct eccentric coma and eccentric curvature of field. .

  More preferably, the reflecting surfaces 11 and 21 have a rotationally symmetric shape formed by rotating an arbitrary-shaped line segment including an odd-order term within the section including the rotation center axis 1 around the rotation symmetry axis 1. Further, correction with a higher degree of freedom can be performed, which is preferable in terms of aberration correction.

  More preferably, by using a solid inner surface such as a cylindrical surface as the image surface 2 (Example 3), the size of the rear group 20 can be reduced.

  More preferably, in the projection system, particularly when the display element is not a self-luminous type, the configuration of the illumination light source part is simplified by using the outer surface of the display element that displays a three-dimensional image (Examples 1 and 2). Can be realized.

  When used in an imaging optical system, it is desirable to have an angle limiting means for shielding unnecessary light, and for example, it can be limited by an aperture arranged on the rotational symmetry axis 1.

  Further, in the case of a projection optical system, in order to limit the angle of light rays emitted from the display surface 2 of the display element, it is preferable to use an illuminating means that illuminates the display surface 2 of the display element having an angle characteristic.

  As described above, the present invention is an optical system capable of forming an image from 360 ° omnidirectional image without various aberrations or projecting an image to 360 ° omnidirectional without any aberrations. It is possible to configure an optical system with the reflecting surfaces 11 and 21 having a rotationally symmetric shape with respect to the rotation center axis 1. Since the rotationally symmetric element can be processed by the same processing method as a general rotationally symmetric aspherical surface, it can be manufactured at low cost.

  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, for example, as shown in FIG. 1, a reference plane set so as to include the rotation center axis 1 from a distant object plane (meaning a distant object point conjugate with the image plane 2). This is based on the result of forward ray tracing through (the origin of coordinates (X, Y, Z)), toward the entrance pupil 4 s, and through the reflecting surfaces 11 and 12 to the image plane 2.

  In forward ray tracing, for example, as shown in FIG. 1, the coordinate system uses the reference plane position obtained by projecting the entrance pupil 4m on the meridional surface on the rotation center axis 1 as the origin of the decentered optical surface of the decentered optical system, and the rotation center axis 1 The direction away from the image plane 2 is the Y-axis positive direction, and the plane of the paper in FIG. 1 is the YZ plane. The direction opposite to the far object side currently considered in the plane of FIG. 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.

  The aspheric surface is a rotationally symmetric aspheric surface given by the following definition.

^{Z = (Y 2 / R)} / [1+ {1- (1 + k) Y 2 / R 2} 1/2]
+ AY ⁴ + bY ⁶ + cY ⁸ + dY ¹⁰ +...
... (a)
However, Z is an optical axis (axial principal ray) with the light traveling direction being positive, and Y is a direction perpendicular to the optical axis. Here, R is a paraxial radius of curvature, k is a conic constant, a, b, c, d,... Are fourth-order, sixth-order, eighth-order, and tenth-order aspherical coefficients, respectively. The Z axis of this defining formula is the axis of a rotationally symmetric aspherical surface.

The toric surface includes an X toric surface and a Y toric surface, which are defined by the following equations, respectively. A straight line passing through the origin of the surface shape and perpendicular to the optical surface is the axis of the toric surface. Taking the XYZ Cartesian coordinate system with respect to the origin of the surface shape,
X toric surface
F (X) = Cx · X ² / [1+ {1− (1 + k) Cx ² · X ² } ^1/2 ] + aX ⁴ + bX ⁶ + cX ⁸ + dX ^10.
Z = F (X) + (1/2) Cy {Y ² + Z ² −F (X) ² } (b)
The curve F (X) is rotated around an axis parallel to the X axis through the center of the Y axis direction curvature Cy in the Z axis direction. As a result, the surface is aspheric in the XZ plane and circular in the YZ plane.

Y toric surface
F (Y) = Cy · Y ² / [1+ {1− (1 + k) Cy ² · Y ² } ^1/2 ] + aY ⁴ + bY ⁶ + cY ⁸ + dY ^10.
Z = F (Y) + (1/2) Cx {X ² + Z ² −F (Y) ² } (c)
The curve F (Y) is rotated around an axis parallel to the Y axis through the center of the X axis direction curvature Cx in the Z axis direction. As a result, the surface is aspheric in the YZ plane and circular in the XZ plane.

Here, Z is the amount of deviation from the tangent plane with respect to the origin of the surface shape, Cx is the X-axis direction curvature, Cy is the Y-axis direction curvature, k is the conic coefficient, and a, b, c, and d are aspherical coefficients. In addition, between the X-axis direction radius of curvature Rx, the Y-axis direction radius of curvature Ry, and the curvatures Cx, Cy,
Rx = 1 / Cx, Ry = 1 / Cy
Are in a relationship.

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

  First, the following curve (d) 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 + ····
... (d)
Next, a curve F (Y) obtained by rotating the curve (d) in the positive direction of the X axis and rotating counterclockwise to the positive angle θ (°) 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.

  A cylindrical surface (Y cylindrical surface) having an axis parallel to the Y axis as a central axis is given as one of the Y toric surfaces, and Ry = ∞, k, a, b, c, d,. , Rx = (radius of cylindrical surface) is given as a Y toric surface.

A conical surface having an axis parallel to the Y axis as a central axis is given as one of the extended rotation free-form surfaces, and RY = ∞, C ₁ , C ₂ , C ₃ , C ₄ , C ₅ ,. , Θ = (conical surface inclination angle), R = (radius of bottom surface in XZ plane).

  In addition, 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. As described above, the eccentricity of each surface is expressed by the amount of eccentricity from the reference surface.

  A sectional view taken along the rotation center axis 1 of the optical system of Example 1 is shown in FIG. 1, and a plan view seen in a direction along the rotation center axis 1 showing the optical path in the optical system is shown in FIG. Further, FIG. 3 shows a lateral aberration diagram in the case of an object point at infinity 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. Note that a negative angle of view means a clockwise angle facing the positive direction of the X axis. same as below.

  This embodiment is composed of a front group 10 and a rear group 20 each consisting of a single reflecting surface 11, 21 that is rotationally symmetric, and forms an intermediate image once at a position 3 between the reflecting surface 11 and the reflecting surface 21. , An imaging optical system that forms an image from 360 ° omnidirectional directions on the outer surface of the cylindrical image surface (display surface) 2, which is composed of two rotationally symmetric reflective surfaces 11, 21, Reference numeral 21 denotes a rotationally symmetric surface having the rotational center axis 1 of the image plane 2 as a rotationally symmetric axis, and both the reflecting surface 11 and the reflecting surface 21 are formed of an extended rotation free-form surface. The entrance pupil 4s and exit pupil 5s on the sagittal plane are arranged at a distance on the Y axis of the rotational symmetry axis (rotation center axis) 1, and the entrance pupil 4m on the meridional plane and the entrance pupil 4s on the sagittal plane. The exit pupil 5m on the meridional surface is arranged in the vicinity of the reflecting surface 21 of the rear group 20.

  With this configuration, in forward ray tracking, light from an object point at infinity (projection plane in reverse ray tracing) passes through the entrance pupils 4s and 4m on the rotation center axis 1 to the reflecting surface 11 of the front group 10 on the Y axis. Is incident on the decentered optical path obliquely, and is reflected there to form an intermediate image at a position 3 between the reflecting surface 11 and the reflecting surface 21, and after the intermediate image is formed, the reflecting surface with respect to the rotation center axis 1 is formed. 11 is incident on the reflecting surface 21 in the eccentric arrangement of the rear group 20 on the opposite side to the reflecting position of 11 at an oblique optical path obliquely with respect to the Y axis, and is reflected there and exited on the sagittal plane away from the entrance pupil 4s on the Y axis. Advancing toward the pupil 5s, the light enters the outer surface of the cylindrical image surface (display surface) 2 on the incident side of the exit pupil 5s to form an image of the object point.

  Because of such an eccentric arrangement, light from 360.degree. Omnidirectional directions is sequentially reflected by the two reflecting surfaces 11 and 21, and does not interfere with the image plane 2. The vertical angle of view of 20.degree. A high-definition image can be formed in the range of °.

The specification of this Example 1 is
Horizontal field of view 360 °
Vertical angle of view 20 °
Entrance pupil diameter 2.00mm
The size of the image is a cylindrical surface with a diameter of 9.60 mm and a height of 3.07 mm.

  FIG. 4 shows a cross-sectional view taken along the rotation center axis 1 of the optical system of Example 2, and FIG. 5 shows a plan view seen in the direction along the rotation center axis 1 showing the optical path in the optical system. FIG. 6 shows a lateral aberration diagram in the case of an object point at infinity of the entire optical system of this example.

  In this embodiment, the front group is made of a transparent medium 15 having an annular shape, having an inner reflection surface 11 and an incident refracting surface 13, and having a cross-sectional reflection prism-like refractive index larger than 1 with the rotation center axis 1 as a rotational symmetry axis. 10 and a rear group 20 made of a transparent medium 25 that is annular and has an internal reflection surface 21 and an exit refracting surface 24 and has a cross-sectional reflection prism-like refractive index larger than 1 with the rotation center axis 1 as a rotational symmetry axis. The transparent medium 15 and the transparent medium 25 are continuous, and an intermediate image is formed once at a position 3 between the reflecting surface 11 and the reflecting surface 21 in the continuous transparent media 15 and 25, and the cylinder is formed. An imaging optical system that forms images from 360 ° omnidirectional directions on the outer surface of the image surface (display surface) 2 of the surface, two rotationally symmetric reflecting surfaces 11 and 21, and two rotationally symmetric refracting surfaces 13; 24, the reflecting surfaces 11, 21 and the refracting surfaces 13, 24 are This is also composed of a rotationally symmetric surface with the rotational center axis 1 of the image plane 2 as the rotational symmetry axis, and the reflecting surface 11 and the reflecting surface 21 are both composed of extended rotation free-form surfaces, and the refracting surfaces 13 and 24 are both. It consists of a toric surface. The entrance pupil 4s and exit pupil 5s on the sagittal plane are arranged at a distance on the Y axis of the rotational symmetry axis (rotation center axis) 1, and the entrance pupil 4m on the meridional plane and the entrance pupil 4s on the sagittal plane. The exit pupil 5m on the meridional surface is arranged in the vicinity of the reflecting surface 21 of the rear group 20.

  With this configuration, in forward ray tracking, light from an object point at infinity (projection plane in reverse ray tracking) passes through the entrance pupils 4 s and 4 m on the rotation center axis 1 and passes through the entrance refracting surface 13 of the front group 10. The light enters the transparent medium 15 and is incident on the reflecting surface 11 with an eccentric optical path obliquely with respect to the Y axis, and is reflected there to form an intermediate image at a position 3 between the reflecting surface 11 and the reflecting surface 21. After image formation, the light is incident on the reflecting surface 21 of the eccentric arrangement of the rear group 20 opposite to the reflection position of the reflecting surface 11 with respect to the rotation center axis 1 obliquely with respect to the Y axis through the eccentric optical path, and is reflected there. 20 exits the transparent medium 25 through the exit refracting surface 24, proceeds toward the exit pupil 5s on the sagittal plane away from the entrance pupil 4s on the Y axis, and is a cylindrical image surface (display) on the entrance side of the exit pupil 5s. Surface) is incident on the outer surface of 2 and forms an image of an object point.

  Because of such an eccentric arrangement, light from all 360 ° directions is reflected in order by the two reflecting surfaces 11 and 21 through the incident refracting surface 13, and does not interfere with the image surface 2 through the exit refracting surface 24. In addition, a high-definition image can be formed in a range of 20 ° in the vertical angle of view of 10 ° to 30 °.

The specification of Example 2 is
Horizontal field of view 360 °
Vertical angle of view 20 °
Entrance pupil diameter 2.00mm
The size of the image is a cylindrical surface with a diameter of 7.41 mm and a height of 1.75 mm.

  In this embodiment, the object side of the reflecting surface 11 and the refracting surfaces 13 and 24 are added between the reflecting surface 21 and the image surface 2 to increase the angle of view in the meridional section (FIG. 4) direction, The telecentricity on the surface 2 side is improved.

  FIG. 7 shows a cross-sectional view taken along the rotation center axis 1 of the optical system of Example 3, and FIG. 8 shows a plan view seen in the direction along the rotation center axis 1 showing the optical path in the optical system. Further, FIG. 9 shows a lateral aberration diagram in the case of an object point at infinity of the entire optical system of this example.

This embodiment is annular, has an entrance refracting surface 13, inner reflecting surfaces 11 and 12, and an exit refracting surface 14, and has a cross-sectional reflecting prism-like refractive index larger than 1 with the rotation center axis 1 as a rotational symmetry axis. Refraction in the form of a cross-section reflecting prism having a front group 10 made of a transparent medium 15, an annular shape having an entrance refracting surface 23, inner reflecting surfaces 21 and 22, and an exit refracting surface 24, with the rotation center axis 1 as a rotational symmetry axis. The rear group 20 is made of a transparent medium 25 having a ratio larger than 1, and has a diaphragm 6 coaxially with the rotation center axis 1 between the front group 10 and the rear group 20. The optical system includes a position 3 ₁ between the incident refracting surface 13 and the internal reflecting surface 11 of the front unit 10, position 3 ₂ of two between the incident refracting surface 23 and internal reflecting surface 21 of the rear unit 20 An imaging optical system that forms an intermediate image and forms an image from 360 ° in all directions on the inner surface of a cylindrical image surface (display surface) 2, and includes four rotationally symmetric reflective surfaces 11, 12, and 21. , 22 and four rotationally symmetric refracting surfaces 12, 14, 23, 24, which are composed of rotationally symmetric surfaces with the rotational center axis 1 of the image plane 2 as the rotationally symmetric axis. The surface 13 is composed of a toric surface, the reflecting surfaces 11, 12, 21, and 22 are all composed of extended rotation free-form surfaces, the refracting surfaces 14 and 23 are composed of spherical surfaces, and the refracting surface 24 is composed of It consists of an extended rotation free-form surface. The entrance pupil 4m on the meridional plane is positioned near the entrance refracting surface 13 of the front group 10, and the entrance pupil 4s and the exit pupil 5s on the sagittal plane have a distance on the Y axis of the rotational symmetry axis (rotation center axis) 1. The exit pupil 5 m on the meridional surface is disposed between the reflecting surface 22 and the refracting surface 24 of the rear group 20.

  With this configuration, in forward ray tracking, light from an object point at infinity (projection plane in reverse ray tracing) passes through the entrance pupil 4m on the meridional plane, enters the transparent medium 15 through the entrance refracting surface 13 of the front group 10. Then, the light is reflected by the reflecting surfaces 11 and 12 on the opposite side to the incident position of the refracting surface 13 with respect to the rotation center axis 1 in order through the eccentric optical path, and exits the transparent medium 15 via the exit refracting surface 14 near the rotation center axis 1 Then, it enters the transparent medium 25 by entering the incident refracting surface 23 of the rear group 20 through the diaphragm 6, and the reflecting surfaces 21, 22 on the opposite side to the reflecting positions of the reflecting surfaces 11, 12 with respect to the rotation center axis 1. Are sequentially reflected through the decentered optical path, exit the transparent medium 25 through the exit refracting surface 24 opposite to the reflection position of the reflecting surfaces 21 and 22, and exit the exit pupil 5s on the sagittal plane away from the entrance pupil 4s on the Y axis. Toward the entrance, cylindrical shape on the entrance side of the exit pupil 5s It is incident on the inner surface of the image surface (display surface) 2 to form an image of the object point.

  Because of such an eccentric arrangement, light from 360 ° omnidirectional direction interferes with the image plane 2 via the four reflecting surfaces 11, 12, 21, 22 and the four refracting surfaces 12, 14, 23, 24. In addition, a high-definition image can be formed in a range of 40 ° in the vertical angle of view from −20 ° to + 20 °.

The specification of this Example 3 is
Horizontal field of view 360 °
Vertical angle of view 40 °
Entrance pupil diameter 1.00mm
The size of the image is a cylindrical surface with a diameter of 42.64 mm and a height of 4.62 mm.

  The configuration parameters of Examples 1 to 3 are shown below. In the table below, “YTR” indicates a Y toric surface, and “ERFS” indicates an extended rotation free-form surface. “RE” indicates a reflective surface.

Example 1
Surface number Curvature radius Surface spacing Eccentricity Refractive index Abbe number Object surface ∞ ∞
1 ∞ (entrance pupil)
2 ERFS [1] (RE) Eccentricity (1)
3 ERFS [2] (RE) Eccentricity (2)
Image surface YTR [1] Eccentricity (3)
ERFS [1]
RY -31.95
θ 0.00
R -19.57
C ₄ 1.7241 × 10 ^-4
C ₅ 1.0141 × 10 ^-6
ERFS [2]
RY 20.23
θ 11.42
R 20.49
C ₄ -4.3235 × 10 ^-5
C ₅ -1.8018 × 10 ^-5
YTR [1]
Rx 4.80
Ry ∞
Eccentricity (1)
X 0.00 Y -7.12 Z 0.00
α 0.00 β 0.00 γ 0.00
Eccentricity (2)
X 0.00 Y -21.70 Z 0.00
α 0.00 β 0.00 γ 0.00
Eccentricity (3)
X0.00 Y-20.92 Z0.00.
α 0.00 β 0.00 γ 0.00

Example 2
Surface number Curvature radius Surface spacing Eccentricity Refractive index Abbe number Object surface ∞ ∞
1 ∞ (entrance pupil)
2 ERFS [1] Eccentricity (1) 1.5163 64.1
3 ERFS [2] (RE) Eccentricity (2) 1.5163 64.1
4 ERFS [3] (RE) Eccentricity (3) 1.5163 64.1
5 ERFS [4] Eccentricity (4)
Image surface YTR [1] Eccentricity (5)
ERFS [1]
RY -7.23
θ -17.71
R -10.00
ERFS [2]
RY -25.38
θ 4.12
R -18.46
C ₄ 6.3491 × 10 ^-5
C ₅ 5.8712 × 10 ^-6
ERFS [3]
RY 16.07
θ 17.45
R 15.69
C4 7.2941 × 10 ^-5
C5 -2.6769 × 10 ^-5
ERFS [4]
RY -3.73
θ 0.00
R 5.00
YTR [1]
Rx 3.70
Ry ∞
Eccentricity (1)
X 0.00 Y -3.64 Z 0.00
α 0.00 β 0.00 γ 0.00
Eccentricity (2)
X 0.00 Y -6.59 Z 0.00
α 0.00 β 0.00 γ 0.00
Eccentricity (3)
X 0.00 Y -24.33 Z 0.00
α 0.00 β 0.00 γ 0.00
Eccentricity (4)
X 0.00 Y -22.93 Z 0.00
α 0.00 β 0.00 γ 0.00
Eccentricity (5)
X 0.00 Y -22.67 Z 0.00
α 0.00 β 0.00 γ 0.00.

Example 3
Surface number Curvature radius Surface spacing Eccentricity Refractive index Abbe number Object surface ∞ ∞
1 ∞ (entrance pupil)
2 ERFS [1] Eccentricity (1) 1.5163 64.1
2 ERFS [2] (RE) Eccentricity (2) 1.5163 64.1
3 ERFS [3] (RE) Eccentricity (3) 1.5163 64.1
4 -12.88 Eccentricity (4)
5 ∞ (diaphragm surface) Eccentricity (5)
6 14.40 Eccentricity (6) 1.5163 64.1
7 ERFS [4] (RE) Eccentricity (7) 1.5163 64.1
8 ERFS [5] (RE) Eccentricity (8) 1.5163 64.1
9 ERFS [6] Eccentricity (9)
Image surface YTR [1] Eccentricity (10)
ERFS [1]
RY 6.92
θ -37.24
R 38.64
ERFS [2]
RY -56.93
θ -30.73
R -32.14
C ₄ -1.2781 × 10 ^-5
ERFS [3]
RY -52.66
θ -78.35
R -12.58
C ₄ 2.1075 × 10 ^-4
ERFS [4]
RY -40.70
θ -92.41
R 8.11
C ₄ -1.8706 × 10 ^-4
ERFS [5]
RY 45.82
θ -44.86
R 12.99
C ₄ 4.7910 × 10 ^-4
ERFS [6]
RY -8.96
θ -36.50
R -18.32
C ₅ 5.9339 × 10 ^-4
YTR [1]
Rx -21.32
Ry ∞
Eccentricity (1)
X 0.00 Y 0.00 Z 0.00
α 0.00 β 0.00 γ 0.00
Eccentricity (2)
X 0.00 Y -17.32 Z 0.00
α 0.00 β 0.00 γ 0.00
Eccentricity (3)
X 0.00 Y 4.19 Z 0.00
α 0.00 β 0.00 γ 0.00
Eccentricity (4)
X 0.00 Y -30.72 Z 0.00
α -90.00 β 0.00 γ 0.00
Eccentricity (5)
X 0.00 Y -31.66 Z 0.00
α -90.00 β 0.00 γ 0.00
Eccentricity (6)
X 0.00 Y -32.60 Z 0.00
α -90.00 β 0.00 γ 0.00
Eccentricity (7)
X 0.00 Y -54.38 Z 0.00
α 0.00 β 0.00 γ 0.00
Eccentricity (8)
X 0.00 Y -35.22 Z 0.00
α 0.00 β 0.00 γ 0.00
Eccentric (9)
X 0.00 Y -43.03 Z 0.00
α 0.00 β 0.00 γ 0.00
Eccentricity (10)
X 0.00 Y -43.08 Z 21.32
α 0.00 β 0.00 γ 0.00.

  Although the optical system of the present invention has been described based on the first to third embodiments, the Y toric is concentric with the rotation center axis 1 on the object side away from the entrance pupils 4m and 4s. A lens is added, and this Y toric lens is also a lens composed of a rotationally symmetric surface with respect to the Y axis (rotation center axis 1). This toric lens has no power in the X direction, while Y By giving a negative power in the direction (in the cross section of FIG. 1 and the like), it becomes possible to take a larger angle of view in the cross section direction including the rotational symmetry axis 1. 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, on the object side of the entrance pupils 4m and 4s, not only one Y toric lens having a negative meniscus lens cross section but also two or three meniscus lenses can be used to generate more image distortion. Can be reduced. In addition to the lens, it is also easy to project or image an arbitrary direction by reflecting and refracting the light beam with a reflection surface or prism that is rotationally symmetric with respect to the rotation center axis 1.

  Further, by using the reflection surfaces 11 to 12, 21 to 22 and the transparent media 15 and 25 that are rotationally symmetric around the rotation center axis 1 of the optical system of the present invention as they are, an image having an angle of view of 360 ° in all directions can be obtained. Although it can be photographed or projected, its reflecting surfaces 11-12, 21-22, and transparent media 15 and 25 are cut by a cross section including the rotation center axis 1 to one half, one third, two thirds, etc. By doing so, an image with an angle of view around the central axis 1 of 180 °, 120 °, 240 °, etc. may be taken or projected.

  As described above, the optical system of the present invention is described as an imaging optical system that forms an image on a cylindrical image plane from 360 ° in all directions (all circumferences) with the rotation center axis (rotation symmetry axis) 1 in the vertical direction. However, with the optical path reversed, the central axis of rotation (rotation symmetry axis) 1 is oriented in the vertical direction, 360 ° in all directions (all circumferences), on a far cylindrical or hemispherical screen, etc. It can also be used as a projection optical system that projects an image of a three-dimensional display surface such as a cone.

  Furthermore, the image surface 2 is not limited to a cylindrical surface, and may be a rotationally symmetric curved surface such as a conical surface or a spherical surface.

  Further, the toric surface and the extended rotation free-form surface can be constituted by a Fresnel surface. Moreover, the optical system of the present invention can also be used as a full-circumference observation optical system of an in-tube observation device such as an endoscope. Further, the reflection surface can be configured by forming a linear Fresnel reflection surface having a groove in the circumferential direction into a cylindrical shape.

  Further, the object point distance is not limited to infinity, but may be a predetermined finite distance, and an image position corresponding to the object point distance may be selected.

  FIG. 10 shows a schematic optical path (a) when the optical system of the present invention is used as a panoramic photographing optical system and a schematic optical path (b) when used as a panoramic projection optical system. When used as a panoramic imaging optical system, as shown in FIG. 10 (a), a rotationally symmetrical three-dimensional imaging surface 2 such as a cylindrical surface or a conical surface is concentric with the rotational symmetry axis 1 of the optical system 30 of the present invention. The image pickup device 31 is arranged, and the light 33 from the 360 ° omnidirectional object is incident on the optical system 30, so that the panoramic image can be formed on the image pickup surface 2 and can be picked up.

  When used as a panoramic projection optical system, as shown in FIG. 10B, a rotationally symmetrical three-dimensional display surface 2 such as a cylindrical surface or a conical surface is concentric with the rotational symmetry axis 1 of the optical system 30 of the present invention. When the display element 35 is arranged, an omnidirectional image to be projected on the display surface 2 is displayed, and the illumination light source 36 disposed behind the display surface 2 of the display element 35 is turned on, projection light from the display surface 2 is displayed. 37 can project an omnidirectional image on a distant cylindrical or hemispherical screen through the optical system 30.

It is sectional drawing taken along the rotation center axis | shaft of the optical system of Example 1 of this invention. FIG. 3 is a plan view of the optical path in the optical system of Example 1 as viewed in the direction along the rotation center axis. FIG. 6 is a lateral aberration diagram in the case of an infinite object point in the entire optical system of Example 1. It is sectional drawing taken along the rotation center axis | shaft of the optical system of Example 2 of this invention. FIG. 6 is a plan view seen in a direction along a rotation center axis showing an optical path in the optical system of Example 2. FIG. 6 is a transverse aberration diagram for an object point at infinity of the entire optical system according to Example 2. It is sectional drawing taken along the rotation center axis | shaft of the optical system of Example 3 of this invention. FIG. 6 is a plan view seen in a direction along a rotation center axis showing an optical path in the optical system of Example 3. FIG. 10 is a transverse aberration diagram for an object point at infinity of the entire optical system according to Example 3. It is a figure which shows the schematic optical path (a) when using the optical system of this invention as a panoramic imaging optical system, and the schematic optical path (b) when using as a panorama projection optical system.

Explanation of symbols

1 ... Center of rotation (axis of rotational symmetry)
2 ... Image surface (display surface)
3, 3 ₁ , 3 ₂ ... Intermediate image position 4 s. Sagittal plane entrance pupil 4 m... Meridional plane entrance pupil 5 s. Reflective surface 13 ... Incident refracting surface 14 ... Ejecting refracting surface 15 ... Transparent medium 20 ... Rear group 21, 22 ... Reflecting surface 23 ... Incident refracting surface 24 ... Ejecting refracting surface 25 ... Transparent medium 30 ... Optical system (present invention)
31 ... Image sensor 33 ... Light from object 35 ... Display element 36 ... Illumination light source 37 ... Projection light

Claims (8)

An optical system that forms an image from a 360 ° omnidirectional direction on a rotationally symmetric solid image surface,
The first reflective surface and the second reflective surface are provided in the order in which the images from all 360 ° directions are incident,
The first reflecting surface and the second reflecting surface are both rotationally symmetric reflecting surfaces,
The first reflecting surface reflects an image incident from all directions of the 360 ° to form an intermediate image,
The second reflecting surface reflects the image reflected by the first reflecting surface to form an image on the three-dimensional image surface,
The optical system according to claim 1, wherein the intermediate image is between the first reflecting surface and the second reflecting surface . The optical system according to claim 1, wherein the rotationally symmetric three-dimensional image surface, the first reflecting surface, and the second reflecting surface are coaxial. 3. The optical system according to claim 2, wherein the entrance pupil of the sagittal section and the exit pupil of the sagittal section are arranged at different positions on the rotational symmetry axis of the first reflecting surface and the second reflecting surface. . The first reflecting surface and the second reflecting surface have a rotationally symmetric shape formed by rotating a line segment having an arbitrary shape not having a symmetric surface in a cross section including a rotationally symmetric axis around the rotationally symmetric axis. The optical system according to claim 1, further comprising: an optical system according to claim 1. The first reflection surface and the second reflection surface have a rotationally symmetric shape formed by rotating an arbitrary line segment including an odd-order term in a cross section including a rotational symmetry axis around the rotational symmetry axis. The optical system according to any one of claims 1 to 3, wherein:   The optical system according to claim 1, wherein the image plane is the rotationally symmetrical three-dimensional inner surface.   6. The optical system according to claim 1, wherein the image plane is the rotationally symmetric solid outer surface.   6. The optical system according to claim 1, wherein an object plane and an image plane of the optical system are reversed and used in a projection optical system.

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