WO2024004271A1 - 光学系、ステレオ光学系、ステレオ撮像装置、撮像装置および画像投写装置 - Google Patents

光学系、ステレオ光学系、ステレオ撮像装置、撮像装置および画像投写装置 Download PDF

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WO2024004271A1
WO2024004271A1 PCT/JP2023/006779 JP2023006779W WO2024004271A1 WO 2024004271 A1 WO2024004271 A1 WO 2024004271A1 JP 2023006779 W JP2023006779 W JP 2023006779W WO 2024004271 A1 WO2024004271 A1 WO 2024004271A1
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Prior art keywords
optical system
center
reduction
reflective surface
conjugate
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English (en)
French (fr)
Japanese (ja)
Inventor
卓也 今岡
裕昭 岡山
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Panasonic Intellectual Property Management Co Ltd
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Panasonic Intellectual Property Management Co Ltd
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Publication of WO2024004271A1 publication Critical patent/WO2024004271A1/ja
Priority to US18/987,771 priority patent/US20250138407A1/en
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B35/00—Stereoscopic photography
    • G03B35/08—Stereoscopic photography by simultaneous recording
    • G03B35/10—Stereoscopic photography by simultaneous recording having single camera with stereoscopic-base-defining system
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B17/00—Systems with reflecting surfaces, with or without refracting elements
    • G02B17/08—Catadioptric systems
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B30/00—Optical systems or apparatus for producing three-dimensional [3D] effects, e.g. stereoscopic images
    • G02B30/20—Optical systems or apparatus for producing three-dimensional [3D] effects, e.g. stereoscopic images by providing first and second parallax images to an observer's left and right eyes
    • G02B30/34—Stereoscopes providing a stereoscopic pair of separated images corresponding to parallactically displaced views of the same object, e.g. three-dimensional [3D] slide viewers
    • G02B30/35—Stereoscopes providing a stereoscopic pair of separated images corresponding to parallactically displaced views of the same object, e.g. three-dimensional [3D] slide viewers using reflective optical elements in the optical path between the images and the observer
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B35/00—Stereoscopic photography
    • G03B35/08—Stereoscopic photography by simultaneous recording
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B35/00—Stereoscopic photography
    • G03B35/18—Stereoscopic photography by simultaneous viewing
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B35/00—Stereoscopic photography
    • G03B35/18—Stereoscopic photography by simultaneous viewing
    • G03B35/22—Stereoscopic photography by simultaneous viewing using single projector with stereoscopic-base-defining system

Definitions

  • the present disclosure relates to an optical system using a prism.
  • the present disclosure also relates to a stereo optical system and a stereo imaging device using such an optical system.
  • the present disclosure also relates to an imaging device and an image projection device using such an optical system.
  • Patent Document 1 discloses an imaging optical system including a prism in which an incident surface, a reflective surface, and an exit surface are integrated.
  • the present disclosure provides an optical system that can be manufactured with a small number of parts, has a smaller size and lower height, and can easily achieve a wider angle.
  • the present disclosure also provides a stereo optical system and a stereo imaging device using such an optical system.
  • the present disclosure also provides an imaging device and an image projection device using such an optical system.
  • One aspect of the present disclosure is an optical system having a reduction conjugate point on a reduction side and an expansion conjugate point on an expansion side that are optically conjugate with each other,
  • a prism having a first transmission surface located on the enlargement side, a second transmission surface located on the reduction side, and at least three reflection surfaces located on the optical path between the first transmission surface and the second transmission surface.
  • the prism has a meridional surface through which light rays reflected by the at least three reflective surfaces pass,
  • the at least three reflecting surfaces include a first reflecting surface and a second reflecting surface in order from the enlargement side to the reduction side, and a most reduction side reflecting surface located on the most reduction side, intermediate imaging positions having a conjugate relationship with the reduction conjugate point and the enlargement conjugate point, respectively, are positioned inside the prism;
  • the first reflective surface is provided in a region where a plurality of chief rays traveling inside the prism are converged.
  • a stereo optical system includes a plurality of the above optical systems, and each of the second transmission surfaces of the plurality of optical systems is arranged adjacent to each other.
  • a stereo imaging device includes the stereo optical system; It has a single imaging surface corresponding to the plurality of second transmission surfaces, and each optical image formed by the plurality of optical systems is received by a divided surface obtained by dividing the imaging surface to generate an electrical image signal. and an image sensor for converting into.
  • An imaging device includes the optical system described above and an imaging element that receives an optical image formed by the optical system and converts it into an electrical image signal.
  • An image projection device includes the above optical system and an image forming element that generates an image to be projected onto a screen via the optical system.
  • the optical system According to the optical system according to the present disclosure, it can be manufactured with a small number of parts, it can be made smaller and lower in height, and it can easily realize a wide angle.
  • FIG. 1(A) is an overall schematic diagram showing an example of a stereo optical system according to the present disclosure.
  • FIG. 1(B) is an overall schematic diagram showing an example of a stereo imaging device according to the present disclosure.
  • FIG. 9(A) is a schematic perspective view showing several light beams passing through a prism of the optical system according to Example 1.
  • FIG. 1(A) is an overall schematic diagram showing an example of a stereo optical system according to the present disclosure.
  • FIG. 1(B) is an overall schematic diagram showing an example of a stereo imaging device according to the present disclosure.
  • FIG. 9(B) is a schematic perspective view showing the three-dimensional shape of each transmission surface and each reflection surface of the prism.
  • FIG. 10(A) is a plan view showing the first reflective surface and the surrounding area.
  • Figure 10(B) is a cross-sectional view Explanatory diagram showing the definitions of angles ⁇ t1, ⁇ m2, ⁇ t2
  • a block diagram showing an example of an image projection device according to the present disclosure A block diagram showing an example of an imaging device according to the present disclosure
  • the optical system according to the present disclosure is used in an imaging device that collects light emitted from an object located on an extension line on the enlargement side and forms an optical image of the object on the imaging surface of an image sensor arranged on the reduction side. can.
  • the optical system according to the present disclosure can be used in a stereo optical system and a stereo imaging device for capturing a stereogram that allows images to be recognized as three-dimensional using binocular parallax.
  • FIG. 1(A) is an overall schematic diagram showing an example of a stereo optical system according to the present disclosure
  • FIG. 1(B) is an overall schematic diagram showing an example of a stereo imaging device according to the present disclosure
  • FIG. 2 is a plan view showing an example of a stereo optical system.
  • the stereo imaging device 1 includes a stereo optical system 10S including a free-form prism and an image sensor 20, and generally has two imaging windows 2L and 2R separated by a distance of a baseline length that produces binocular parallax.
  • the stereo optical system 10S is configured by integrating two left and right prisms 10L and 10R.
  • methods for integrating the prisms a) a method of bonding two prisms manufactured separately, b) a method of simultaneous integral molding using a mold, etc. can be adopted.
  • the left prism 10L is provided with a first transmission surface T1L, a first reflection surface M1L, a second reflection surface M2L, a third reflection surface M3L, a fourth reflection surface M4L, and a second transmission surface T2L.
  • the right prism 10R is provided with a first transmission surface T1R, a first reflection surface M1R, a second reflection surface M2R, a third reflection surface M3R, a fourth reflection surface M4R, and a second transmission surface T2R.
  • the two second transmitting surfaces T2L and T2R are arranged adjacent to each other, and behind the two second transmitting surfaces T2L and T2R there is a single imaging surface corresponding to the second transmitting surfaces T2L and T2R.
  • a single image sensor 20 is provided that receives each optical image from the two second transmission surfaces T2L and T2R using a dividing surface obtained by dividing the imaging surface. Note that, instead of the single image sensor 20, a plurality of image sensors having a single image sensor may be provided.
  • the light emitted from the object enters the photographing windows 2L and 2R, passes through the first transmission surfaces T1L and T1R, is reflected inside the prism, and exits from the second transmission surfaces T2L and T2R to cover the cover glass CG.
  • the image is formed on the imaging surface of the image sensor 20 via the. This imaging plane corresponds to the reduction conjugate point on the reduction side, and the object corresponds to the enlargement conjugate point on the enlargement side.
  • Embodiment 2 An optical system according to Embodiment 2 of the present disclosure will be described below using FIGS. 3 to 11.
  • FIG. 3 is a layout diagram showing the optical system 10 according to the first embodiment.
  • the optical system 10 corresponds to the prisms 10L and 10R shown in FIG. 2, respectively, and has an enlargement conjugate point (not shown, surface number S1) on the enlargement side located on the left side of the drawing, and a reduction conjugate point on the reduction side located on the right side of the drawing. It has a conjugate point CP (surface number S21) (for surface numbers S1, S21, etc., refer to numerical examples described later).
  • the image area on the conjugate plane including the reduction conjugate point CP is defined as a reduction side rectangular area having a longitudinal direction (X direction) and a transversal direction (Y direction). Further, the image area on the conjugate plane including the enlarged conjugate point is also defined as an enlarged rectangular area having a longitudinal direction and a lateral direction.
  • the rectangular area on the reduction side and the rectangular area on the enlargement side have an optically conjugate imaging relationship. The chief ray travels along an optical axis parallel to the normal direction of this rectangular area on the reduction side.
  • This rectangular area on the reduced side has an aspect ratio of, for example, 3:2, 4:3, 16:9, 16:10, 256:135, etc., and corresponds to the imaging area of an image sensor in the case of an imaging device. , corresponds to the image display area of the image forming element in the case of an image projection device.
  • This intermediate imaging position appears as a Y-direction intermediate image IMy on the meridional plane (YZ plane), and as an X-direction intermediate image IMx on the sagittal plane (XY plane).
  • YZ plane Y-direction intermediate image
  • XY plane X-direction intermediate image IMx on the sagittal plane
  • FIGS. 3, 5, and 7 only the Y-direction intermediate image IMy in the meridional plane is shown, and the X-direction intermediate image IMx in the sagittal plane is omitted.
  • the reflecting surface is curved, the reflection position of the light beam located within the meridional surface and the reflection position of the light beam located outside the meridional surface are shifted.
  • the optical system 10 includes a prism that can be made of a transparent medium, such as glass or synthetic resin, and a cover glass CG provided in front of the image sensor 20.
  • the cover glass CG is composed of a flat plate with zero optical power, and may be omitted.
  • the prism includes a first transmission surface T1 located on the enlargement side, a second transmission surface T2 located on the reduction side, and four transmission surfaces located on the optical path between the first transmission surface T1 and the second transmission surface T2. It has a first reflective surface M1, a second reflective surface M2, a third reflective surface M3, and a fourth reflective surface M4.
  • the first transmission surface T1 (surface number S1) has a free-form surface shape with a convex surface facing the enlargement side.
  • the first reflective surface M1 (surface number S4) has a substantially planar free-form surface shape with zero optical power.
  • the second reflective surface M2 (surface number S8) has a free-form surface shape with a concave surface facing the direction in which the light beam incident on the second reflective surface M2 is reflected.
  • the third reflective surface M3 (surface number S12) has a free-form surface shape with a concave surface facing the direction in which the light beam incident on the third reflective surface M3 is reflected.
  • the fourth reflective surface M4 (surface number S16) has a free-form surface shape with a concave surface facing the direction in which the light beam incident on the fourth reflective surface M4 is reflected.
  • the second transmission surface T2 (surface number S18) has a free-form surface shape with a convex surface facing the reduction side. In this embodiment, the fourth reflective surface M4 corresponds to the most reduced reflective surface.
  • FIG. 9(A) is a schematic perspective view showing several light beams passing through the prism of the optical system 10 according to Example 1.
  • FIG. 9(B) is a schematic perspective view showing the three-dimensional shape of each transmitting surface and each reflecting surface of the prism.
  • the imaging device the light emitted from the rectangular area on the enlarged side passes through the first transmission surface T1, is reflected in order from the first to fourth reflection surfaces M1 to M4, passes through the second transmission surface T2, and passes through the cover.
  • the light is collected by the image sensor 20 via the glass CG.
  • the first reflective surface M1 is provided in a region where a plurality of chief rays traveling inside the prism converge, and eliminates light traveling to the surrounding area of the first reflective surface M1. It can function as an aperture AS to utilize only the reflected light.
  • FIG. 4 is a lateral aberration diagram of the optical system 10 according to Example 1.
  • the three wavelengths used in the calculation are 656.2725 nm, 587.5618 nm, and 486.1327 nm. From these graphs, it can be seen that a clear light spot is obtained in the rectangular region on the reduction side (for example, the imaging surface), and excellent optical performance is exhibited.
  • FIG. 5 is a layout diagram showing the optical system 10 according to the second embodiment.
  • the optical system 10 corresponds to the prisms 10L and 10R shown in FIG. 2, respectively, and has an enlargement conjugate point (not shown, surface number S1) on the enlargement side located on the upper right side of the drawing, and a reduction conjugate point located on the lower right side of the drawing. It has a reduced conjugate point CP (surface number S21) on the side (for surface numbers S1, S21, etc., refer to numerical examples described later).
  • this optical system 10 has a configuration similar to that of Example 1, the explanation that overlaps with Example 1 may be omitted below.
  • This intermediate imaging position appears as a Y-direction intermediate image IMy on the meridional plane (YZ plane), and as an X-direction intermediate image IMx on the sagittal plane (XY plane).
  • the optical system 10 includes a prism made of a transparent medium and a cover glass CG.
  • the prism includes a first transmission surface T1 located on the enlargement side, a second transmission surface T2 located on the reduction side, and three third transmission surfaces located on the optical path between the first transmission surface T1 and the second transmission surface T2. It has one reflective surface M1, a second reflective surface M2, and a third reflective surface M3.
  • the first transmission surface T1 (surface number S1) has a free-form surface shape with a convex surface facing the enlargement side.
  • the first reflective surface M1 (surface number S4) has a substantially planar free-form surface shape with zero optical power.
  • the second reflective surface M2 (surface number S8) has a free-form surface shape with a concave surface facing the direction in which the light beam incident on the second reflective surface M2 is reflected.
  • the third reflective surface M3 (surface number S12) has a free-form surface shape with a concave surface facing the direction in which the light beam incident on the third reflective surface M3 is reflected.
  • the second transmission surface T2 (surface number S14) has a free-form surface shape with a convex surface facing the reduction side. In this embodiment, the third reflective surface M3 corresponds to the most reduced reflective surface.
  • the light emitted from the rectangular area on the enlarged side passes through the first transmission surface T1, is reflected in order from the first to third reflection surfaces M1 to M3, passes through the second transmission surface T2, and passes through the cover.
  • the light is collected by the image sensor 20 via the glass CG.
  • the first reflective surface M1 is provided in a region where a plurality of chief rays traveling inside the prism converge, and eliminates light traveling to the surrounding area of the first reflective surface M1. It can function as an aperture AS to utilize only the reflected light.
  • FIG. 6 is a lateral aberration diagram of the optical system 10 according to Example 2.
  • the normalized coordinates and wavelengths of each graph are the same as in Example 1. From these graphs, it can be seen that a clear light spot is obtained in the rectangular region on the reduction side (for example, the imaging surface), and excellent optical performance is exhibited.
  • FIG. 7 is a layout diagram showing the optical system 10 according to the third embodiment.
  • the optical system 10 corresponds to the prisms 10L and 10R shown in FIG. 2, respectively, and has an enlargement conjugate point (not shown, surface number S1) on the enlargement side located on the left side of the drawing, and a reduction conjugate point on the reduction side located on the right side of the drawing. It has a conjugate point CP (surface number S21) (for surface numbers S1, S21, etc., refer to numerical examples described later).
  • this optical system 10 has a configuration similar to that of Example 1, the explanation that overlaps with Example 1 may be omitted below.
  • intermediate imaging positions are located that are conjugate with the reduction conjugate point CP and the enlargement conjugate point, respectively.
  • This intermediate imaging position appears as a Y-direction intermediate image IMy on the meridional plane (YZ plane), and as an X-direction intermediate image IMx on the sagittal plane (XY plane).
  • the optical system 10 includes a prism made of a transparent medium and a cover glass CG.
  • the prism includes a first transmission surface T1 located on the enlargement side, a second transmission surface T2 located on the reduction side, and four transmission surfaces located on the optical path between the first transmission surface T1 and the second transmission surface T2. It has a first reflective surface M1, a second reflective surface M2, a third reflective surface M3, and a fourth reflective surface M4.
  • the first transmission surface T1 (surface number S1) has a free-form surface shape with a convex surface facing the enlargement side.
  • the first reflective surface M1 (surface number S4) has a substantially planar free-form surface shape with zero optical power.
  • the second reflective surface M2 (surface number S8) has a free-form surface shape with a concave surface facing the direction in which the light beam incident on the second reflective surface M2 is reflected.
  • the third reflective surface M3 (surface number S12) has a free-form surface shape with a concave surface facing the direction in which the light beam incident on the third reflective surface M3 is reflected.
  • the fourth reflective surface M4 (surface number S16) has a free-form surface shape with a concave surface facing the direction in which the light beam incident on the fourth reflective surface M4 is reflected.
  • the second transmission surface T2 (surface number S18) has a free-form surface shape with a convex surface facing the reduction side. In this embodiment, the fourth reflective surface M4 corresponds to the most reduced reflective surface.
  • the light emitted from the rectangular area on the enlarged side passes through the first transmission surface T1, is reflected in order from the first to fourth reflection surfaces M1 to M4, passes through the second transmission surface T2, and passes through the cover.
  • the light is collected by the image sensor 20 via the glass CG.
  • the first reflective surface M1 is provided in a region where a plurality of chief rays traveling inside the prism converge, and eliminates light traveling to the surrounding area of the first reflective surface M1. It can function as an aperture AS to utilize only the reflected light.
  • FIG. 8 is a lateral aberration diagram of the optical system 10 according to Example 3.
  • the normalized coordinates and wavelengths of each graph are the same as in Example 1. From these graphs, it can be seen that a clear light spot is obtained in the rectangular region on the reduction side (for example, the imaging surface), and excellent optical performance is exhibited.
  • the prism has a first transmission surface T1, a second transmission surface T2, a first to fourth reflection surface M1 to M4 (Examples 1 and 3), or a first to third reflection surface. Since the reflecting surfaces M1 to M3 (Example 2) are integrated, it is possible to reduce assembly adjustments between optical components and to reduce costs. Further, the optical surface having the power of a prism does not have an axis of rotational symmetry, that is, it is formed as a free-form surface with different curvatures on the X axis and Y axis perpendicular to the surface normal. By using a free-form surface that can define different curvatures on the X and Y axes for the optical surface of the prism, the degree of freedom for correcting distortion increases, and the optical system can be made smaller.
  • the optical system 10 is an optical system having a reduction conjugate point on the reduction side and an expansion conjugate point on the enlargement side that are optically conjugate with each other, A first transmission surface T1 located on the enlargement side, a second transmission surface T2 located on the reduction side, and at least three reflection surfaces located on the optical path between the first transmission surface T1 and the second transmission surface T2.
  • the prism has a meridional surface through which light rays reflected by the at least three reflective surfaces M1 to M4 pass,
  • the at least three reflecting surfaces include a first reflecting surface M1 and a second reflecting surface M2 in order from the enlargement side to the reduction side, and the most reduction side reflecting surfaces M3 and M4 located closest to the reduction side, intermediate imaging positions having a conjugate relationship with the reduction conjugate point CP and the enlargement conjugate point, respectively, are positioned inside the prism;
  • the first reflective surface M1 is provided in a region where a plurality of chief rays traveling inside the prism are converged.
  • the first reflective surface can function as an aperture of a diaphragm that adjusts the amount of light passing through the optical system. Therefore, it is possible to optimize the amount of light at the contracting conjugate point or the expanding conjugate point, and it is possible to prevent stray light and off-axis rays from passing through. Furthermore, since the prism has a plurality of transmitting surfaces and reflective surfaces integrated, it can be made low in height with a small number of members, it can be made smaller by making its effective diameter smaller, and it is also easier to make the prism wider.
  • the optical system 10 may satisfy the following condition (1). -2.0 ⁇ rxm1/rym1 ⁇ 2.0...(1) here, rxm1: the x-direction partial radius of curvature at the position where the reference ray passing through the center of the first reflective surface M1 and the center of the conjugate plane including the reduction conjugate point CP passes through the first reflective surface M1 rym1: the aforementioned A partial radius of curvature in the y direction at a position where the reference ray passing through the center of the first reflective surface M1 and the center of the conjugate plane including the reduction conjugate point CP passes through the first reflective surface M1.
  • x direction the meridional surface y direction: a direction parallel to the meridional surface and the first reflective surface M1.
  • Equation (1) optimizes the relationship between the x-direction partial radius of curvature and the y-direction partial radius of curvature of the first reflective surface.
  • the reflective surface is inclined.
  • optical system 10 may satisfy the following condition (1a). -1.0 ⁇ rxm1/rym1 ⁇ 1.0...(1a)
  • the optical system 10 may satisfy the following condition (2). 0.0 ⁇ rxt1/ryt1 ⁇ 4.0...(2) here, rxt1: x-direction partial radius of curvature at the position where the reference ray passing through the center of the first reflecting surface M1 and the center of the conjugate plane including the reduction conjugate point CP passes through the first transmitting surface T1 ryt1: the aforementioned Partial radius of curvature in the y direction at the position where the reference ray passing through the center of the first reflective surface M1 and the center of the conjugate plane including the reduction conjugate point CP passes through the first transmission surface T1.
  • x direction the meridional surface y direction: a direction parallel to the meridional surface and the first transmission surface T1.
  • Equation (2) optimizes the relationship between the x-direction partial radius of curvature and the y-direction partial radius of curvature of the first transmission surface. For the reasons mentioned above, the first reflective surface is inclined. By satisfying equation (2), astigmatism occurring in the optical system can be suppressed. If the upper limit of equation (2) is exceeded or the lower limit is exceeded, astigmatism will worsen.
  • optical system 10 may satisfy the following condition (2a). 2.0 ⁇ rxt1/ryt1 ⁇ 3.0...(2a)
  • the optical system 10 may satisfy the following condition (3). -7.0 ⁇ rxt2/ryt2 ⁇ 0.0...(3) here, rxt2: the x-direction partial radius of curvature at the position where the reference ray passing through the center of the first reflecting surface M1 and the center of the conjugate plane including the reduction conjugate point CP passes through the second transmitting surface T2 ryt2: the aforementioned Partial radius of curvature in the y direction at the position where the reference ray passing through the center of the first reflective surface M1 and the center of the conjugate plane including the reduction conjugate point CP passes through the second transmission surface T2.x direction: the meridional surface y direction: a direction parallel to the meridional surface and the second transmission surface T2.
  • Equation (3) optimizes the relationship between the x-direction partial radius of curvature and the y-direction partial radius of curvature of the second transmission surface. For the reasons mentioned above, the first reflective surface is inclined. By satisfying equation (3), astigmatism occurring in the optical system can be suppressed. If the upper limit of equation (3) is exceeded or the lower limit is exceeded, astigmatism will worsen.
  • optical system 10 may satisfy the following condition (3a). -5.0 ⁇ rxt2/ryt2 ⁇ -3.0...(3a)
  • the optical system 10 may satisfy the following condition (4). 0.0 ⁇ rxm2/rym2 ⁇ 3.0...(4) here, rxm2: x-direction partial radius of curvature at the position where the reference ray passing through the center of the first reflective surface M1 and the center of the conjugate plane including the reduction conjugate point CP passes through the second reflective surface M2 rym2: the aforementioned A partial radius of curvature in the y direction at a position where the reference ray passing through the center of the first reflecting surface M1 and the center of the conjugate plane including the reduction conjugate point CP passes through the second reflecting surface M2.x direction: the meridional surface y direction: a direction parallel to the meridional surface and the second reflective surface M2.
  • Equation (4) optimizes the relationship between the x-direction partial radius of curvature and the y-direction partial radius of curvature of the second reflective surface. For the reasons mentioned above, the first reflective surface is inclined. By satisfying equation (4), astigmatism occurring in the optical system can be suppressed. If the upper limit of equation (4) is exceeded or the lower limit is exceeded, astigmatism will worsen.
  • optical system 10 may satisfy the following condition (4a). 0.0 ⁇ rxm2/rym2 ⁇ 2.0...(4a)
  • the optical system 10 may satisfy the following condition (5). 0.0 ⁇ rxms/ryms ⁇ 3.0...(5) here, rxms: x-direction partial radius of curvature at the position where the reference ray passing through the center of the first reflecting surface M1 and the center of the conjugate plane including the reduction conjugate point CP passes through the most reduction side reflection surfaces M3 and M4 ryms: partial radius of curvature in the y direction at the position where the reference ray passing through the center of the first reflecting surface M1 and the center of the conjugate plane including the reduction conjugate point CP passes through the most reduction side reflection surfaces M3 and M4; x direction: a direction perpendicular to the meridional surface; y direction: a direction parallel to the meridional surface and the most reduced reflection surfaces M3 and M4.
  • Equation (5) optimizes the relationship between the partial radius of curvature in the x direction and the partial radius of curvature in the y direction of the reflection surface on the most reduced side. For the reasons mentioned above, the first reflective surface is inclined. By satisfying equation (5), astigmatism occurring in the optical system can be suppressed. If the upper limit of equation (5) is exceeded or the lower limit is exceeded, astigmatism will worsen.
  • optical system 10 may satisfy the following condition (5a). 0.0 ⁇ rxms/ryms ⁇ 2.0...(5a)
  • the optical system 10 may satisfy the following condition (6). 5.0 ⁇
  • Equation (6) optimizes the angle between the normal to the first transmission surface and the normal to the first reflection surface. If the lower limit of equation (6) is not reached, the surfaces will spatially interfere with each other. If the upper limit is exceeded, it becomes difficult to manufacture prisms.
  • optical system 10 may satisfy the following condition (6a). 10.0 ⁇
  • the optical system 10 may satisfy the following condition (7).
  • Equation (7) optimizes the angle between the normal to the first reflective surface and the normal to the second reflective surface. If the upper limit of equation (7) is exceeded, it becomes difficult to manufacture the prism.
  • optical system 10 may satisfy the following condition (7a).
  • the optical system 10 may satisfy the following condition (8). 10.0 ⁇
  • Equation (8) optimizes the angle between the normal to the most-reduced reflective surface and the normal to the second transmission surface. If the lower limit of equation (8) is not reached, the surfaces will spatially interfere with each other. If the upper limit is exceeded, it becomes difficult to manufacture prisms.
  • optical system 10 may satisfy the following condition (8a). 15.0 ⁇
  • the optical system 10 may satisfy the following condition (9). 0.40 ⁇
  • Equation (9) optimizes the distance between the transmitting surface and the reflective surface.
  • the angle of incidence of off-axis rays on the reduction side increases.
  • the upper limit is exceeded, the size of the first transmission surface becomes too large.
  • optical system 10 may satisfy the following condition (9a). 0.50 ⁇
  • the first reflective surface M1 may have a reflectance of 80% or more, and the area surrounding the first reflective surface M1 may have a reflectance of less than 10%.
  • the intermediate imaging position may be between the second reflective surface M2 and the most reduced reflective surfaces M3 and M4.
  • the prism can be made smaller.
  • the first reflective surface M1 and the surrounding area may not be on the same plane.
  • the surrounding area may include a conical surface extending from the first reflective surface M1 to the opposite side of the first transmitting surface T1.
  • the surrounding area may be provided with a material or shape that absorbs or scatters light.
  • FIG. 10(A) is a plan view showing the first reflective surface and the surrounding area
  • FIG. 10(B) is a sectional view thereof.
  • the first reflective surface M1 is composed of, for example, a circular mirror
  • its surrounding area TP is provided with a function of eliminating ghost light.
  • a) the surrounding area TP has a shape that is not on the same plane as the first reflecting surface M1, for example, an inclined surface to scatter the light
  • b) the surrounding area TP has a shape that is not on the same plane as the first reflecting surface M1, and scatters the light.
  • a material or shape that absorbs or scatters light in the surrounding region TP including a conical surface, for example an inverted tapered conical surface or a pyramidal surface, extending on the opposite side of the transmission surface T1; c) a material or shape that absorbs or scatters light, for example, Black painting, providing grains (fine uneven shapes) to absorb or scatter light, etc. may be employed, and any one of these methods may be used, or two or more methods may be combined.
  • the free-form surface shape of the prism optical surface is defined by the following equation using a local orthogonal coordinate system (x, y, z) with the surface vertex as the origin.
  • z Sag amount on the plane parallel to the z-axis
  • c Curvature at the surface vertex
  • k Conic coefficient
  • C j Coefficient of the monomial x m y n (x ⁇ m y ⁇ n in the table).
  • one prism optical surface has multiple surface numbers (for example, four surface numbers S4 to S7 for the first reflective surface M1), but these are coordinate transformations between global coordinates and local coordinates during numerical calculation. means the surface number used for Moreover, "decenter & return" in the table means coordinate transformation between global coordinates and local coordinates during numerical calculation.
  • Table 4 shows lens data regarding the optical system of Numerical Example 2 (corresponding to Example 2).
  • Table 5 shows the eccentricity type and ⁇ rotation amount of the prism optical surface.
  • Table 6 shows the free-form surface shape data of the prism optical surface.
  • Table 7 shows lens data regarding the optical system of Numerical Example 3 (corresponding to Example 3).
  • Table 8 shows the eccentricity type and ⁇ rotation amount of the prism optical surface.
  • Table 9 shows the free-form surface shape data of the prism optical surface.
  • Table 10 shows the corresponding values of each of formulas (1) to (9) in each numerical example 1 to 3.
  • Table 11 shows the numerical values of the variables in each of formulas (1) to (9) in each numerical example 1 to 3.
  • FIG. 12 is a block diagram illustrating an example of an image projection device according to the present disclosure.
  • the image projection device 100 includes the optical system 10 disclosed in Embodiment 2, an image forming element 101, a light source 102, a control unit 110, and the like.
  • the image forming element 101 is composed of a liquid crystal, a DMD, etc., and generates an image to be projected onto the screen SR via the optical system 10.
  • the light source 102 is composed of an LED (light emitting diode), a laser, or the like, and supplies light to the image forming element 101.
  • the control unit 110 is composed of a CPU, an MPU, or the like, and controls the entire device and each component.
  • the optical system 10 may be configured as an interchangeable lens that can be detachably attached to the image projection device 100, or may be configured as a built-in lens that is integrated into the image projection device 100.
  • the above-described image projection device 100 can project a short focus and large screen with a small device using the optical system 10 according to the second embodiment.
  • FIG. 13 is a block diagram illustrating an example of an imaging device according to the present disclosure.
  • the imaging device 200 includes the optical system 10 disclosed in Embodiment 2, an imaging element 201, a control unit 210, and the like.
  • the image sensor 201 is composed of a CCD (charge-coupled device) image sensor, a CMOS image sensor, etc., and receives an optical image of the object OBJ formed by the optical system 10 and converts it into an electrical image signal.
  • the control unit 110 is composed of a CPU, an MPU, or the like, and controls the entire device and each component.
  • the optical system 10 may be configured as an interchangeable lens that can be detachably attached to the imaging device 200, or may be configured as a built-in lens that is integrated into the imaging device 200.
  • the above-described imaging device 200 can perform short-focus and large-screen imaging with a small device. Further, by using a plurality of imaging devices 200, a stereo camera, a multi-angle camera, etc. can be realized.
  • the present disclosure is applicable to image projection devices such as projectors and head-up displays, and imaging devices such as digital still cameras, digital video cameras, surveillance cameras in surveillance systems, web cameras, and vehicle-mounted cameras.
  • imaging devices such as digital still cameras, digital video cameras, surveillance cameras in surveillance systems, web cameras, and vehicle-mounted cameras.
  • the present disclosure is applicable to optical systems that require high image quality, such as projectors, digital still camera systems, and digital video camera systems.

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  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Lenses (AREA)
  • Optical Elements Other Than Lenses (AREA)
  • Stereoscopic And Panoramic Photography (AREA)
PCT/JP2023/006779 2022-06-28 2023-02-24 光学系、ステレオ光学系、ステレオ撮像装置、撮像装置および画像投写装置 Ceased WO2024004271A1 (ja)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000066105A (ja) * 1998-08-21 2000-03-03 Olympus Optical Co Ltd 結像光学系
JP2001083422A (ja) * 1999-09-09 2001-03-30 Canon Inc 光学素子及びそれを用いた光学装置
JP2017044722A (ja) * 2015-08-24 2017-03-02 キヤノン株式会社 ステレオ撮像光学系および撮像装置
WO2017150486A1 (ja) * 2016-03-04 2017-09-08 キヤノン株式会社 光学系、それを備える撮像装置及び投影装置
JP2018097189A (ja) * 2016-12-14 2018-06-21 キヤノン株式会社 複眼撮像光学系および複眼撮像装置
CN110471173A (zh) * 2019-08-05 2019-11-19 同济大学 一种带衍射面的四反中波红外取景器光学系统

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000066105A (ja) * 1998-08-21 2000-03-03 Olympus Optical Co Ltd 結像光学系
JP2001083422A (ja) * 1999-09-09 2001-03-30 Canon Inc 光学素子及びそれを用いた光学装置
JP2017044722A (ja) * 2015-08-24 2017-03-02 キヤノン株式会社 ステレオ撮像光学系および撮像装置
WO2017150486A1 (ja) * 2016-03-04 2017-09-08 キヤノン株式会社 光学系、それを備える撮像装置及び投影装置
JP2018097189A (ja) * 2016-12-14 2018-06-21 キヤノン株式会社 複眼撮像光学系および複眼撮像装置
CN110471173A (zh) * 2019-08-05 2019-11-19 同济大学 一种带衍射面的四反中波红外取景器光学系统

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