JP2008083398A - Compound-eye optics and optical apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compound-eye optics that has a wide angle, less distortion, and high resolution, and to provide an optical apparatus using the same. <P>SOLUTION: The compound-eye optics 1 has a plurality of single-eyes 2 composed of at least two lens groups. The single eyes 2 are arranged nonparallel to each other. An image is formed on a curved face or polyhedron formed by them. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wide-angle imaging optical system and an optical apparatus using the same.

  Wide-angle imaging optical systems are used in imaging devices employed in endoscopes, capsule endoscopes, surveillance cameras, robot eyes, and the like. However, when a coaxial wide-angle lens is used as such an imaging optical system as in the prior art, there is a drawback in that negative distortion occurs in which an image formed at the peripheral portion is reduced. .

As a method for solving this drawback, Patent Documents 1 and 2 and Non-Patent Document 1 describe the use of a compound eye optical system.
Japanese Patent Publication No. 6-14141 JP 58-219522 A "SCIENCE VOL 312 28 APRIL 2006" pp. 557-561 The American Association for the Advancement of Science published

  However, when compound eye optical systems such as those described in Patent Documents 1 and 2 and Non-Patent Document 1 are used, the field of view of the single eye composing the compound eye overlaps, so there is a drawback that the resolving power is low. It was.

  The present invention has been made in view of such problems of the prior art, and an object of the present invention is a compound-eye optical system having a wide angle, a small amount of distortion, and a high resolving power, and an optical system using the same. Is to provide a device.

  In order to achieve the above object, the compound eye optical system of the present invention has a plurality of single eyes composed of at least two lens groups, and the single eyes are arranged non-parallel to each other on a curved surface or a polyhedron. An image was formed.

  In order to achieve the above object, the optical apparatus of the present invention combines a compound-eye optical system having a plurality of single eyes and an imaging element whose imaging surface has a curved surface shape or a polyhedral shape.

  According to the compound eye optical system and the optical apparatus using the same of the present invention, an image having a high resolving power can be obtained with less occurrence of distortion aberration as in the related art even at a wide angle.

  Hereinafter, the present invention will be described in detail based on illustrated embodiments.

  FIG. 1 is a schematic diagram illustrating an optical device according to the present embodiment. FIG. 2 is an enlarged view of a single eye constituting the compound eye optical system of the present embodiment of FIG.

  First, the configuration of the compound eye optical system 1 of the present embodiment will be described with reference to FIG. The compound eye optical system 1 is composed of a plurality of individual eyes 2. The individual eyes 2 are arranged radially so that their optical axes L intersect at a point Q. Note that an image pickup device 3 having a spherical image pickup surface with the point Q as a spherical center is disposed at a position serving as the image plane of the individual eye 2. The individual eye 2 is composed of three groups of lenses.

  The image sensor 3 used in this embodiment and other embodiments described later is a CCD, a C-MOS image sensor, or the like. Since the shape of the imaging surface only needs to substantially match the shape of the image surface formed on the imaging surface, it is not limited to a spherical shape, and may be a curved surface, an aspherical surface, or a free curved surface. Absent. Furthermore, it may be a polyhedral shape. Note that a ball semiconductor, an organic semiconductor, or the like is preferably used for manufacturing an imaging element having such an imaging surface.

  In this embodiment, an image formed by the single eye 2 and photographed by the image sensor 3 is transmitted from the image sensor 3 to the signal processing circuit 9 and converted into a video signal. The video signal thus obtained is processed by the image processing apparatus 10. Thereafter, an image is displayed on the display device 11 based on the processed video signal.

  Note that the compound-eye optical system 1 of the present embodiment can perform wide-angle imaging as the number of the individual eyes 2 that are configured increases. In addition, as is common to the optical apparatus of the present application, the image processing apparatus 10 may be omitted when image processing is not performed.

  Next, the individual eye 2 constituting the compound-eye optical system 1 of the present embodiment will be described with reference to FIGS. It is assumed that the object surface is a spherical surface with the point Q as a sphere center.

  The single eye 2 constituting the compound-eye optical system 1 is composed of an objective lens 2a, a field lens 2b, and a relay lens 2c in order from the object side. A partition wall 4 is disposed from the side surface of the objective lens 2a to the side surface of the relay lens 2c.

  When observing the object 6 on the object plane 5, first, an inverted image 6a of the object 6 is formed on the field lens 2b by the objective lens 2a. Then, an inverted image of the inverted image 6a, that is, an erect image 6b of the object 6 is formed on the imaging surface of the imaging element 3 by the relay lens 2c. In the case of the present embodiment, since each object image formed by the plurality of individual eyes 2 is an erect image, these images can be smoothly connected to each other.

In addition, the individual eye 2 of the present embodiment is configured to satisfy the following conditional expression (1).
However,
R ₁ : Distance from the spherical center to the object plane R ₂ : Distance from the spherical center to the image plane β : Magnification of individual eye β ₁ : magnification of objective lens β ₂ : magnification of relay lens.

  Therefore, when the compound eye optical system 1 of the present embodiment is used, an image that is β times as large as the object 6 on the object plane 5 is captured by the image sensor 3 by the plurality of individual eyes 2 of the compound eye optical system 1. It will be formed on the surface.

When the object plane 5 is sufficiently far from the spherical center Q, that is, compared with the distance from the spherical center Q to the imaging surface of the imaging device 3, the focal length of the objective lens 2a, and the focal length of the relay lens 2c, When the distance from the center Q to the object plane 5 is sufficiently large, the following conditional expressions (2) and (3) are satisfied.
However,
f ₁ is the focal length of the objective lens.

  The compound eye optical system 1 used in the optical apparatus of Example 1 may be configured as follows.

  In the compound eye optical system 1 according to the first embodiment, the objective lens 2a, the field lens 2b, and the relay lens 2c are each configured by a single lens, but may be configured by a lens group including a plurality of lenses. Further, the objective lens 2a, the field lens 2b, and the relay lens 2c may be configured by heterogeneous lenses having a distributed refractive index. In addition, when comprising by a heterogeneous lens, lenses may be couple | bonded.

  In the compound eye optical system 1 according to the first embodiment, the partition wall 4 that blocks light from the side surface of the objective lens 2a to the side surface of the relay lens 2c is disposed, thereby allowing light from the other adjacent eyes 2 to enter. Generation of ghosts and flares is prevented. The field lens 2b may be omitted when the light beam can pass to the image plane.

  Further, when the compound eye optical system 1 of the first embodiment is configured to capture an image formed by one single eye 2 with a plurality of pixels of the image sensor 3, the resolution of the obtained image is improved.

In addition, since the compound eye optical system 1 of Example 1 is practically allowed to have some blurring of the image, it is not necessary to satisfy the following conditional expression (4) instead of the conditional expression (1). The eye 2 may be configured.
However,
R ₁ : Distance from the spherical center to the object plane R ₂ : Distance from the spherical center to the image plane β : Single eye magnification.

Further, in the compound eye optical system 1 of the first embodiment, when the pixels of the image pickup device 3 used in the compound eye optical system 1 are rough, the following conditional expression (5) is used instead of the conditional expression (4). The individual eye 2 may be configured so as to satisfy.
However,
R ₁ : Distance from the spherical center to the object plane R ₂ : Distance from the spherical center to the image plane β : Single eye magnification.

Moreover, the following conditional expression (6) may be satisfied for the individual eye 2 constituting the compound-eye optical system 1 of the first embodiment.
However,
R ₁ : Distance from the spherical center to the object plane R ₂ : Distance from the spherical center to the image plane β : Single eye magnification.

  In this case, the range imaged by one individual eye 2 partially overlaps the range imaged by another adjacent individual eye 2. In such a case, the image processing apparatus 10 may perform a process of joining the images formed by the individual eyes 2 together. In such a case, a partition wall may be provided between the relay lens 2 c and the image sensor 3.

Moreover, the following conditional expression (7) may be satisfied in the individual eye 2 constituting the compound-eye optical system 1 of the first embodiment.
However,
R ₁ : Distance from the spherical center to the object plane R ₂ : Distance from the spherical center to the image plane β : Single eye magnification.

  In this case, an image formed by one individual eye 2 and an image formed by another adjacent individual eye 2 overlap each other. In such a case, it is more preferable that the image processing apparatus 10 separates the overlapped images and then performs a process of joining them.

  When the image processing apparatus 10 processes an image formed by the individual eye 2, the individual eye 2 may not be configured to satisfy the conditional expressions (4) and (5).

Finally, numerical data of the compound eye optical system 1 according to the present example is shown.
Distance from sphere center to objective lens: R = 1.5mm
Distance from sphere center to object surface: R ₁ = 10 mm
Distance from sphere center to image plane: R ₂ = 0.5 mm
Focal length of individual eye: f = -0.5mm
Focal length of objective lens: f ₁ = 0.5 mm
Focal length of relay lens: f ₂ = 0.125 mm
Focal length of field lens: f ₃ = 1 / (f ₁ ⁻¹ + (2 × f ₂ ) ⁻¹ )
= 0.1667mm
Objective lens diameter: D = 0.16mm
Minimum required diameter of field lens: D ₃ = 0.05318 mm
Individual F number: Fno = 3.125
F number of objective lens: Fno ₁ = 3.125
Single eye magnification: β = 0.05
Objective lens magnification: β ₁ ≒ -0.05
Magnification of relay lens: β ₂ = −1
Viewing angle of a single eye: ΔΦ = Tan ⁻¹ (2 × f ₂ / Fno / (2 × f ₂ + R ₂ ))
= 6.089 degrees Viewing angle of compound eye optical system: 2ω = 180 degrees Individual eye image height: IH = F ₁ × tan (ΔΦ / 2) = 0.02659 mm
Number of eyes constituting the compound eye optical system: N = 2π / (0.000239 × ΔΦ ² )
≒ 709
If one pixel has a diameter of 0.03 mm,
Number of pixels contained in one individual eye: N _k = π × IH ² /(π×0.0015 ² )
≒ 314
Total number of pixels included in compound-eye optical system: N _p = 709 × 314 = 222226
It is.

  In addition, a compound eye optical system having the following configuration may be used for the optical device of the first embodiment.

  FIG. 3 is a partially enlarged view showing another configuration example of the compound eye optical system used in the optical apparatus of the present invention. The compound eye optical system 1 ′ shown in FIG. 3 is configured by arranging the individual eyes 2 ′, 2 ″, 2 ′ ″,... So as not to be parallel to each other. Unlike the compound-eye optical system 1 used in the above, their optical axes L ′, L ″, L ′ ″... Do not intersect at a specific point. In addition, on the image planes of the individual eyes 2 ′, 2 ″, 2 ′ ″..., An imaging element 3 ′ having a free-form surface with a convex imaging surface is disposed.

  In addition, as shown in FIG. 3, the individual eyes 2 ′, 2 ″ 2 ′ ″... Have their optical axes L ′, L ″, L ′ ″. You may arrange | position and may arrange | position so that optical axes may mutually have a twist relationship. This is because, in any case, a single wide-angle image can be obtained by appropriately connecting images formed by the individual eyes by image processing.

  Further, the individual eyes 2 ′, 2 ″, 2 ′ ″... Do not necessarily have the same structure and characteristics. For example, the viewing angles may be different from each other, or the sizes of the lenses to be configured may be different.

  FIG. 4 is a schematic diagram showing an optical device according to the present invention using an optical fiber.

  The optical apparatus of the present embodiment is configured using a compound eye optical system 1 similar to that used in the optical apparatus of the first embodiment. Unlike the first embodiment, the optical apparatus according to the present embodiment is configured such that the incident end 7a is radiated in order from the object side between the compound-eye optical system 1 and the imaging element 3 ″ having a flat imaging surface. A bundle of formed optical fibers 7 and a lens 8 are arranged. In addition, the optical device includes a signal processing circuit 9, an image processing device 10, and a display device 11.

  In the optical apparatus of the present embodiment, first, the light emitted from the compound eye optical system 1 enters the incident end 7 a of the optical fiber 7. Then, the light is emitted from the emission end 7 b of the optical fiber 7, and an image is formed on the image sensor 3 ″ by the lens 8. Thereafter, an image photographed by the image sensor 3 ″ is transmitted to the signal processing circuit 9, converted into a video signal, processed by the image processing device 10, and displayed as an image on the display device 11.

  In the present embodiment, the optical fiber 7 is used as an example of the optical waveguide, but another optical waveguide may be used.

  FIG. 5 is a schematic diagram showing a capsule endoscope that is an optical device according to the present invention.

  The capsule endoscope 12 of the present embodiment includes a compound eye optical system 1 similar to that used in the first and second embodiments, and an image pickup device inside a dome portion 12a formed by transparent members at both ends of the capsule. Element 3 is arranged. Further, the power source 12b, the signal processing circuit 9 and the like are disposed between the two dome portions 12a. An illumination white LED 12c is disposed as a light source. The image processing device 10 and the display device 11 are disposed outside the capsule endoscope 12.

  An image obtained by the capsule endoscope 12 is first converted into a video signal by the signal processing circuit 9 disposed inside the capsule endoscope 12. Thereafter, the video signal is wirelessly transmitted to the image processing device 10 disposed outside the capsule endoscope 12, processed, and displayed as an image on the display device 11.

  In addition, when using the compound eye optical system 1 for such a capsule endoscope 12, it is preferable to configure the compound eye optical system 1 so that the viewing angle of the compound eye optical system 1 can be photographed in a range exceeding 180 degrees. In the example, the viewing angle is configured to be 210 degrees.

  FIG. 6 is a schematic diagram showing the periphery of the distal end portion of an electronic endoscope that is an optical apparatus according to the present invention.

  In the electronic endoscope 13 of the present embodiment, the compound eye optical system 1 similar to that used in Embodiments 1 to 3 and the image sensor 3 are disposed at the tip. Further, around the compound eye optical system 1, an illumination white LED 13a is disposed as a light source.

  An image captured by the electronic endoscope 13 is transmitted from the image sensor 3 to a signal processing circuit (not shown) and converted into a video signal. The video signal thus obtained is processed by an image processing device (not shown). Thereafter, an image is displayed on a display device (not shown) based on the processed video signal. Note that the curved surface described in this application includes a polyhedron.

  Finally, the definitions of terms used in the above description are described below.

  An optical device is a device including an optical system or an optical element. The optical device alone may not function. That is, a part of the apparatus may be used.

  The optical device includes an imaging device, an observation device, a display device, a lighting device, a signal processing device, and the like.

  Examples of imaging devices include film cameras, digital cameras, PDA (personal digital assistant) digital cameras, robot eyes, interchangeable lens digital single lens reflex cameras, television cameras, video recording devices, electronic video recording devices, camcorders, VTRs. Cameras, mobile phone digital cameras, mobile phone TV cameras, electronic endoscopes, capsule endoscopes, in-vehicle cameras, satellite cameras, planetary explorer cameras, space probe cameras, surveillance camera cameras, various types Sensor eyes, digital cameras for recording devices, artificial vision, laser scanning microscopes, etc. Digital camera, card-type digital camera, TV camera, VTR camera, video recording camera, mobile phone digital camera, mobile phone TV camera, in-vehicle camera, satellite camera, planetary explorer camera, space probe camera, A digital camera or the like of a recording device is an example of an electronic imaging device.

  Examples of the observation apparatus include a microscope, a telescope, glasses, binoculars, a loupe, a fiberscope, a viewfinder, a viewfinder, a contact lens, an intraocular lens, and artificial vision.

  Examples of the display device include a liquid crystal display, a viewfinder, a game machine (a Sony PlayStation), a video projector, a liquid crystal projector, a head mounted display (HMD), a PDA, a mobile phone, and artificial vision. Etc.

  Examples of the illumination device include a camera strobe, an automobile headlight, an endoscope illumination, an endoscope light source, and a microscope light source.

  Examples of the signal processing device include a mobile phone, a personal computer, a game machine, an optical disk reading / writing device, an optical computer arithmetic device, an optical interconnection device, an optical information processing device, and a PDA.

  The signal processing device includes an information transmission device. An information transmission device is a device that can input and transmit any information such as a remote control such as a mobile phone, a fixed phone, a game machine, a TV, a radio cassette, a stereo, a personal computer, a keyboard of a personal computer, a mouse, a touch panel, etc. Point to. It shall also include a television monitor with an imaging device, a personal computer monitor, and a display.

  The image pickup device refers to, for example, a CCD, C-MOS, image pickup tube, solid-state image pickup device, photographic film or the like.

  The compound eye optical system of the present invention and the optical apparatus using the compound eye optical system can be configured as follows in addition to the description of the scope of claims.

(1) A compound eye optical system comprising a plurality of single eyes composed of at least three lens groups, wherein the single eyes are arranged non-parallel to form an image on a curved surface.

(2) The compound eye optical system according to (1) or (1), wherein the image is an erect image.

(3) The compound-eye optical system according to (1) or (1), wherein the image has a convex shape toward the object.

(4) The compound eye optical system according to claim 1 or (1), wherein the following conditional expression (5) is satisfied.
However,
R ₁ : Distance from the spherical center to the object plane R ₂ : Distance from the spherical center to the image plane β : Single eye magnification.

(5) The compound-eye optical system according to (1) or (1), wherein an incident end of an optical waveguide is disposed on the surface of the image.

(6) The compound eye optical system according to (1) or (1), wherein a partition wall is provided between the lens groups.

(7) The optical apparatus according to (2), wherein the image sensor is made of a semiconductor.

(8) The optical device according to (2), wherein the image sensor is made of an organic semiconductor.

(9) The optical device according to (2), wherein the image sensor is formed of a ball semiconductor.

(10) The optical apparatus according to claim 2, wherein the imaging surface of the imaging device has a convex shape.

(11) The optical apparatus according to claim 2, wherein an image formed by one of the single eyes is picked up by a plurality of pixels of an image pickup device.

(12) An optical apparatus comprising a combination of the compound-eye optical system according to claim 1 or any one of (1) to (6) and an image pickup device having an image pickup surface having a curved surface shape.

(13) The image processing apparatus according to any one of (2) and (7) to (11), further comprising an image processing device that performs a process of joining a plurality of images formed by the individual eyes to form one image. The optical device according to Item.

(14) The optical device according to (12), further including an image processing device that performs processing to connect a plurality of images formed by the individual eyes to form one image.

(15) The optical device according to (13) or (14), wherein the following conditional expression (6) is satisfied.
However,
R ₁ : Distance from the spherical center to the object plane R ₂ : Distance from the spherical center to the image plane β : Single eye magnification.

(16) The optical device according to (13) or (14), wherein the following conditional expression (7) is satisfied.
However,
R ₁ : Distance from the spherical center to the object plane R ₂ : Distance from the spherical center to the image plane β : Single eye magnification.

(17) The optical apparatus according to any one of (2) and (7) to (16), wherein the optical apparatus is an endoscope.

(18) The optical device according to any one of (2) and (7) to (16), wherein the optical device is a capsule endoscope.

(19) An optical apparatus comprising a combination of the optical system according to (5) above and an imaging device having a planar imaging surface shape.

It is a schematic diagram which shows the optical apparatus which concerns on Example 1 of this invention. FIG. 2 is an enlarged view of a single eye constituting the compound eye optical system of FIG. 1. It is the elements on larger scale which show the other structural example of the compound eye optical system of the optical apparatus which concerns on Example 1 of this invention. It is a schematic diagram which shows the optical apparatus using the optical fiber which concerns on Example 2 of this invention. It is a schematic diagram which shows the capsule endoscope which is an optical apparatus which concerns on Example 3 of this invention. It is a schematic diagram which shows the front-end | tip part periphery of the electronic endoscope which is an optical apparatus which concerns on Example 4 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compound eye optical system 2, 2 ', 2'',2''' single eye 2a Objective lens 2b Fielded lens 2c Relay lens 3, 3 ', 3''Image sensor 4 Bulkhead 5 Object surface 6 Object 6a Inverted object Image 6b Erect image of object 7 Optical fiber 7a Optical fiber entrance end 7b Optical fiber exit end 8 Lens 9 Signal processing circuit 10 Image processing device 11 Display device 12 Capsule endoscope 12a Dome portion 12b Power supply 12c, 13a White LED for illumination
13 Electronic endoscope L, L ′, L ″, L ′ ″ Optical axis of single eye Q Ball of imaging element

Claims (2)

  A compound eye optical system comprising a plurality of single eyes composed of at least two lens groups, wherein the single eyes are arranged non-parallel to form an image on a curved surface or a polyhedron.   An optical apparatus in which a compound-eye optical system having a plurality of individual eyes and an imaging element having an imaging surface having a curved surface shape or a polyhedral shape are combined.