JP4136087B2 - Compound eye imaging device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a compound eye imaging apparatus having a plurality of imaging systems.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a method for inputting a three-dimensional image of a subject, photographing with a compound eye imaging device having a plurality of imaging systems (imaging optical systems) is known. In the case of two eyes, this compound-eye imaging device captures a subject with two left and right imaging systems, and grasps the three-dimensional shape of the subject from the parallax between the left and right images of the subject portion. Such grasping of the three-dimensional shape is basically the same method as in the case of using the human right and left eyeballs.
[0003]
When shooting with a compound-eye imaging device, the baseline length (interval between the left and right imaging systems) and the convergence angle (angle formed by the optical axes of the left and right imaging systems) are changed depending on whether the subject is located far or near. Is done.
[0004]
This is because the overlapping area in the left and right images changes depending on whether the subject is located far away or close. For example, when the left and right imaging systems are arranged in parallel, the overlapping area becomes closer to the subject. This is because it is necessary to adjust the optical axis direction of the left and right imaging systems in order to capture the entire image in duplicate.
[0005]
Also, when the distance between the left and right imaging systems is short, the parallax between the left and right images is lost for a long-distance subject, and a sufficient stereoscopic effect cannot be obtained. It needs to be long.
[0006]
As described above, when photographing with a compound-eye imaging device, it is an important elemental technique to adjust the base line length and the convergence angle of the camera according to the subject.
[0007]
FIG. 14 is a diagram illustrating a configuration of an imaging system in a conventional compound eye imaging apparatus. In a conventional compound-eye imaging apparatus, a plurality of ordinary coaxial optical systems are generally arranged. As a method of changing the convergence angle and the base line length, the interval between the optical axes of the coaxial optical system and the angle formed by the optical axes are mechanically changed.
[0008]
In addition, in a compound eye imaging device, a so-called panoramic image having a wider angle in the horizontal direction is also captured by using two or more imaging systems. At this time, the plurality of imaging systems are arranged so that viewpoints can be substantially matched, and only necessary portions for overlapping a plurality of captured images can be overlapped to capture as many different fields of view as possible. At that time, the interval between the optical axes and the angle formed by the optical axes are mechanically changed.
[0009]
Recently, it has become clear that even in non-coaxial optical systems, it is possible to construct an optical system in which aberrations are sufficiently corrected by introducing the concept of a reference axis and making the configuration surface an asymmetric aspherical surface. Japanese Patent Application Laid-Open No. 9-5650 discloses the design method, and Japanese Patent Application Laid-Open Nos. 8-292371 and 8-292372 provide design examples.
[0010]
Such a non-coaxial optical system is called an off-axial optical system. The off-axial optical system includes a curved surface (off-axial curved surface) in which the surface normal at the intersection point with the reference axis of the component surface is not on the reference axis when the reference axis along the ray passing through the image center and the pupil center is considered. In this case, the reference axis has a bent shape.
[0011]
In this off-axial optical system, the constituent surfaces are generally non-coaxial, and no vignetting occurs even on the reflecting surface, so that it is easy to construct an optical system using the reflecting surface. Further, the optical path can be routed relatively freely, and an integrated optical system can be easily formed by a method of integrally forming the constituent surfaces.
[0012]
[Problems to be solved by the invention]
However, in the compound eye imaging device using the conventional coaxial optical system, when changing the convergence angle or the base line length, it is necessary to rotate or move the entire imaging system, so the imaging system is configured with the coaxial optical system. In this case, there is a problem that the entire apparatus becomes large.
[0013]
In particular, during panoramic photography, it is necessary to make the left and right viewpoints substantially coincide, that is, the baseline length, which is the distance between the centers of the entrance pupils of the imaging system, must be almost zero. When there is a convergence angle, the lenses interfere with each other and the base line length can only be shortened to a certain extent, or if the base line length is shortened to an appropriate length, the convergence angle cannot be increased. there were.
[0014]
In addition, in the case of a compound eye imaging device, it is required that the magnification and imaging performance of each of the left and right imaging systems be uniform. Conventionally, each of the left and right imaging systems incorporates a plurality of lenses in a lens barrel. Since it is configured, there is a problem in that the optical characteristics of the left and right imaging systems vary, and it is necessary to adjust the magnification and the like in the left and right imaging systems.
[0015]
Further, FIG. 15 is a diagram conceptually showing an image when panoramic photography is performed with congestion on a conventional imaging system. When panoramic shooting is performed with the imaging system congested ((A) in the same figure), the central viewpoint of each of the left and right imaging systems (the object side extension point of the reference axis of each imaging system) is the ideal central viewpoint of the composite image Therefore, when connecting the left and right images, it is necessary to remove the apparent so-called trapezoidal distortion caused by the difference in the central viewpoint. If this trapezoidal distortion is shared only for image processing, there is a problem that the image quality deteriorates.
[0016]
Accordingly, a first object of the present invention is to provide a compound eye imaging apparatus that can reduce the number of components of each imaging system and can realize a compact configuration.
[0017]
It is a second object of the present invention to provide a compound eye imaging device that can easily change the convergence angle without increasing the baseline length.
[0018]
Furthermore, a third object of the present invention is to provide a compound eye imaging device that can easily change the baseline length.
[0019]
It is a fourth object of the present invention to provide a compound eye imaging device that can suppress variations in imaging performance.
[0020]
Furthermore, a fifth object of the present invention is to provide a compound eye imaging apparatus that can easily switch between a three-dimensional image capturing mode and a panoramic mode.
[0021]
It is a sixth object of the present invention to provide a compound eye imaging apparatus that can obtain an image with little apparent trapezoidal distortion due to the difference between the left and right central viewpoints when synthesizing panoramic images.
[0022]
[Means for Solving the Problems]
  To achieve the above object, the present inventionAccording to the left and rightIn a compound eye imaging device having the imaging system ofSymmetrical and left / rightAn off-axial optical system block including an asymmetric aspherical off-axial reflecting surface and having a refractive power for forming a real image as a whole;Left and rightFor each imaging system, So that the left and right imaging systems are upside downProvidedCompound eye imaging deviceIt is characterized by.
[0023]
Further, according to the present invention, in a compound eye imaging apparatus having left and right imaging systems, an off-axial optical system block that includes an asymmetric aspherical off-axial reflecting surface and has a refractive power for forming a real image as a whole is provided on the left and right sides. It is provided in each of the imaging systems, and at least one of the left and right imaging systems including the off-axial optical system block is rotated by partially or entirely rotating the base line length of the left and right imaging systems. The compound eye imaging device configured as described above is characterized.
[0035]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of a compound eye imaging device of the present invention will be described.
[0036]
[First Embodiment]
FIG. 1 is a diagram illustrating a configuration of a compound eye imaging apparatus according to the first embodiment. In the figure, reference numeral 10 denotes a compound-eye camera head unit for photographing a subject and outputting an image signal.
[0037]
A signal processing unit 20 performs processing for converting an image signal obtained from the compound-eye camera head unit 10 into image data such as a JPEG (Joint Photographic Expert Group) method. An exposure control unit 30 controls the exposure amount of the left and right imaging systems of the compound-eye camera head unit 10 according to the brightness of the subject.
[0038]
Reference numeral 40 denotes a focus control unit which controls focusing on the subject. 50 is a release button. A memory 60 stores image data. Reference numeral 70 denotes a system controller that controls the operation of the entire compound-eye imaging apparatus.
[0039]
FIG. 2 is a diagram illustrating a configuration of the camera head unit 10. In the figure, 11L and 11R are optical elements on the object side, which are off-axial optical system blocks formed of a transparent body such as glass and having a plurality of reflecting surfaces and refractive surfaces.
[0040]
FIG. 3 is a diagram illustrating the shape of the optical element 11R on the object side. A concave refracting surface (incident surface) r11 having a negative refractive power, an reflecting surface r12, a reflecting surface r13, and a convex refracting surface having a positive refractive power (on the surface of the optical element 11R on the object side) An exit surface r14 is formed.
[0041]
The concave refractive surface r11 and the convex refractive surface r14 are spherical. The reflection surfaces r12 and r13 have symmetry in the direction perpendicular to the paper surface, but do not have symmetry in the paper surface and have a rotationally asymmetric aspherical shape as a whole.
[0042]
The other optical element 11L on the object side has a symmetrical shape with the optical element 11R on the object side, and similarly has a concave refractive surface (incident surface), two reflecting surfaces, and a convex refractive surface (exit surface). Specifically, since the optical element 11R has symmetry in the direction perpendicular to the paper surface, the same optical element 11R as the optical element 11L is turned upside down in the paper vertical direction.
[0043]
The optical elements 11R and 11L are made into an integral shape made of a transparent body by molding such as plastic or glass. When molding is performed under constant molding conditions, the optical characteristic variation is small compared to the conventional case where the lens is incorporated into the lens barrel. Can be built.
[0044]
FIG. 4 shows the shape of the image-side optical element 12R. The optical element 12R is a transparent body such as glass having a plurality of reflecting surfaces and refracting surfaces.
[0045]
On the surface of the optical element 12R on the image side, a convex refractive surface (incident surface) r21 having a positive refractive power in the order of passage of light from the object, a reflective surface r22, a reflective surface r23, and a convex refractive surface having a positive refractive power. (Ejection surface) r24 is formed.
[0046]
The convex refractive surfaces r21 and r24 are spherical. The reflection surfaces r22 and r23 have symmetry in the direction perpendicular to the paper surface, but do not have symmetry in the paper surface and have a rotationally asymmetric aspherical shape as a whole.
[0047]
The other optical element 12L on the image side has a symmetrical shape with the optical element 12R on the image side, and similarly has a convex refractive surface (incident surface), two reflecting surfaces, and a convex refractive surface (exit surface). Have. Specifically, since the optical element 12R is symmetrical in the direction perpendicular to the paper surface, the same optical element 12R is turned upside down in the direction perpendicular to the paper surface to form the optical element 12L.
[0048]
The optical element 12R and the optical element 12L are made into an integral shape made of a transparent body by molding such as plastic or glass. As in the case of the optical elements 11R and 11L, it is possible to construct a compound-eye imaging system with a small difference in left and right imaging performance by molding.
[0049]
In FIG. 2, 13L and 13R are diaphragms that limit the amount of light incident on the optical elements 11L and 11R, respectively, and are arranged on the object side where the optical elements 11L and 11R are provided. Reference numerals 14L and 14R denote image sensors such as CCDs, which are arranged at positions where light emitted from the image-side optical elements 12L and 12R forms an image, respectively. The optical elements 11L and 12L, the diaphragm 13L, and the imaging element 14L constitute the left imaging system, and the optical elements 11R and 12R, the diaphragm 13R, and the imaging element 14R constitute the right imaging system, and the two imaging systems are symmetrical. Has been placed.
[0050]
Reference numerals 15L and 15R denote holding members for fixing the optical elements 11L and 11R and the diaphragms 13L and 13R, respectively. Reference numeral 16 denotes a holding member for fixing the optical elements 12L and 12R. Reference numeral 17 denotes a table for holding the holding members 15L, 15R, 16 and the image sensors 14L, 14R.
[0051]
Reference numerals 18L and 18R denote cam grooves formed on the base 17. The holding members 15L and 15R that hold the optical elements 11L and 11R are rotatable around the centers CL and CR along the cam grooves 18L and 18R, respectively. Here, the centers CL and CR are positioned at the centers of curvature of the exit surfaces r14 of the optical elements 11L and 11R, respectively, and the holding members 15L and 15R that hold the optical elements 11L and 11R are mounted on the centers CL and CR as rotation axes. 17 is rotatably attached.
[0052]
Reference numeral 19 denotes a guide groove formed in the table 17. The holding member 16 holding the optical elements 12L and 12R is attached to the base 17 so as to be movable along the guide groove 19.
[0053]
FIG. 5 is a diagram showing the arrangement of the left and right imaging systems and the optical path when the subject is at a long distance. FIG. 6 is a diagram showing the arrangement of the left and right imaging systems and the optical path when the subject is at a short distance. The convergence angle of the left and right imaging systems varies depending on the distance of the subject.
[0054]
In the present embodiment, the light beam (reference axis light beam) that passes through the center point of the effective beam diameter of the stop and reaches the center of the final imaging surface is set to a path that is refracted and reflected by each refracting surface and reflecting surface, respectively. It is represented by a one-dot chain line in the figure.
[0055]
First, the imaging action when the subject is at a long distance (see FIG. 5) will be described using the right imaging system. The light beam incident on the right imaging system from the object is incident on the incident surface r11 of the optical element 11R after the amount of incident light is limited by the diaphragm 13R, reflected by the reflecting surface r12, and then once combined in the vicinity of the reflecting surface r13. And exits from the exit surface r14. Here, the image is formed once in the vicinity of the reflecting surface r13 in order to prevent the imaging system from becoming large by converging the light beam incident from the incident surface r11 on the reflecting surface r13. Can be
[0056]
The light beam emitted from the exit surface r14 enters the entrance surface r21 of the optical element 12R, is reflected by the reflection surfaces r22 and r23, exits from the exit surface r24, and is disposed on the imaging surface. The image is formed on 14R. In this case (see FIG. 5), the optical elements 11R and 12R are arranged so that the directions of the incident reference axis (incident reference axis) and the outgoing reference axis (exit reference axis) are parallel to each other.
[0057]
Further, since the left imaging system is symmetrical with the right imaging system, the light beam incident on the left imaging system forms an image on the imaging element 14L through the same optical path.
[0058]
Next, the imaging action when the subject is at a short distance (see FIG. 6) will be described. In the present embodiment, the optical elements 12L and 12R have a function of a focus lens, and move by the same amount toward the object side from the position in FIG. 5 along the incident and exit reference axes. The movement of the holding member 16 that holds the optical elements 12L and 12R is restricted by the guide groove 19. The optical elements 12L and 12R are disposed on the holding member 16 so that the incident reference axis and the emission reference axis are parallel to each other.
[0059]
The optical elements 11L and 11R are rotated around the centers CL and CR so that the incident reference axes of the optical elements 11L and 11R converge toward the inside. The amount of rotation is regulated by cam grooves 18L and 18R that guide the holding members 15L and 15R that hold the optical elements 11L and 11R, respectively.
[0060]
The movements of the image-side optical elements 12L and 12R and the object-side optical elements 11L and 11R are interlocked with the holding member 16 that moves to the object side (see FIG. 2), and the protrusions 16a and 16b are the holding members 15L and 15R, respectively. , The optical elements 11L and 11R are rotated in a plane including the injection reference axis.
[0061]
The holding members 15L and 15R are always urged by springs (not shown) so as to abut against the protruding portions 16a and 16b of the holding member 16. In this state, the light beam incident on the left and right imaging systems forms an image on the imaging elements 14L and 14R through the same optical path as in FIG.
[0062]
As described above, even if the imaging elements 14L and 14R are arranged so that the distance between them is reduced, the optical elements 11L, 11R, 12L, and 12R use the off-axial optical system block, and thus the distance between the apertures 13L and 13R. The base line length can be increased, and a compact configuration in which the optical elements do not interfere with each other even when congestion is applied as shown in FIG. 6 can be achieved.
[0063]
Next, the overall operation of the compound eye imaging apparatus will be described with reference to FIG. Unless otherwise specified, all operations are controlled by the system controller 70.
[0064]
First, when the release button 50 is operated to generate a release signal, focus control is performed. In the focus control, the respective image signals obtained by the imaging elements 14L and 14R of the left and right imaging systems are converted into image data by the signal processing unit 20, and the phase difference between the center portions of the left and right image data is detected.
[0065]
Then, the subject distance is estimated from the phase difference detected by the focus control unit 40, and the holding member 16 holding the optical elements 12L and 12R having the function of the focus lens of the left and right imaging system is placed at a position corresponding to the subject distance. It moves along the guide groove 19 to focus the left and right imaging system. At this time, the holding members 15L and 15R holding the optical elements 11L and 11R on the object side are rotated in conjunction with the movement of the holding member 16, and the convergence angle changes according to the subject distance.
[0066]
Thereafter, exposure control is performed. The respective image signals obtained by the imaging elements 14L and 14R of the left and right imaging system are converted into image data by the signal processing unit 20. Then, the exposure control unit 30 measures the brightness of the subject from the left and right image data, determines the aperture and shutter speed according to the measured values in the left and right imaging systems, and sets the aperture values of the apertures 13L and 13R. After the change, the image sensors 14L and 14R are exposed at the determined shutter speed.
[0067]
When the respective image signals obtained by the left and right imaging elements 14L and 14R are converted into image data by the signal processing unit 20, the converted image data is stored in the memory 60.
[0068]
As described above, in the first embodiment, it is possible to provide a compound eye imaging apparatus having the compound eye camera head unit 10 capable of adjusting the convergence angle of the camera according to the subject distance. This imaging system is composed of an asymmetrical aspherical off-axial reflecting surface and a plurality of prisms which are off-axial optical system blocks having a positive refractive power, and only some of the prisms are in a plane including the exit reference axis. The angle of convergence can be adjusted by rotating with.
[0069]
Therefore, the imaging system can be configured compactly, and by providing such an imaging system, the entire compound-eye imaging apparatus capable of adjusting the convergence angle can be made compact.
[0070]
In the present embodiment, an asymmetric aspherical off-axial reflecting surface and a prism having a plurality of refractive powers are used as the blocks of the optical elements 11R, 11L, 12R, and 12L. The axial optical system block may be a hollow type block having a reflecting surface as disclosed in JP-A-8-292371 and JP-A-8-292372.
[0071]
In the present embodiment, the left and right imaging system is configured by an off-axial optical system block including four prisms, but the left and right imaging system may be configured by using a prism in which the optical elements 12L and 12R are integrally formed.
[0072]
[Second Embodiment]
FIG. 7 is a diagram illustrating a configuration of a compound eye imaging apparatus according to the second embodiment. In the figure, reference numeral 10A denotes a compound-eye camera head unit for photographing a subject and outputting an image signal.
[0073]
A signal processing unit 20 performs processing for converting an image signal obtained by the compound-eye camera head unit 10A into image data such as a JPEG method. An exposure control unit 30 controls the exposure amount of the left and right imaging system of the compound-eye camera head unit 10A according to the brightness of the subject. Reference numeral 40 denotes a focus control unit which controls focusing on the subject.
[0074]
50 is a release button. A memory 60 stores image data. Reference numeral 70 denotes a system controller that controls the operation of the entire compound-eye imaging apparatus. Reference numeral 80 denotes a baseline length switching unit for switching the baseline length of the compound eye camera head unit 10A.
[0075]
In the second embodiment, a baseline length switching unit 80 is newly provided for the compound-eye imaging device in the first embodiment, and the optical elements 11L and 11R are rotatable around its emission reference axis. Is provided. In the compound eye camera head unit 10A, the convergence angle is fixed. Since other configurations and operations are the same as those in the first embodiment, description thereof will be omitted by assigning the same reference numerals, and the baseline length switching unit 80 having different configurations and operations will be described.
[0076]
In the second embodiment, the base line length switching unit 80 can rotate the object-side optical elements 11L and 11R of the compound-eye camera head unit 10A by 180 ° around the respective emission reference axes. Long and short base line lengths can be switched. FIG. 5 described above represents an optical arrangement in a state where the base line length is long. On the other hand, FIG. 8 is a diagram showing an optical arrangement in a state where the base line length is short. As described above, in the compound-eye camera head unit 10A, the state of the two base lines is switched.
[0077]
In the second embodiment, the base line length is switched between the long and short states by rotating the object-side optical elements 11L and 11R of the compound-eye camera head unit 10A by 180 ° around the respective emission reference axes. However, by configuring the optical elements 11L and 11R to rotate by the same arbitrary amount, the compound-eye camera head unit 10A is set to a state having an intermediate baseline length between the two long and short states. Also good.
[0078]
As described above, in the second embodiment, it is possible to provide a compound-eye imaging apparatus having a compound-eye camera head unit whose baseline length can be switched according to the subject.
[0079]
In addition, the imaging system including the off-axial optical system block is composed of an asymmetric aspherical off-axial reflecting surface and a plurality of prisms having a plurality of refractive powers. Therefore, the imaging system can be made compact. In addition, the entire compound-eye imaging apparatus provided with such an imaging system can be made compact.
[0080]
Further, in the second embodiment, the optical elements 11R, 11L, 12R, and 12L are off-axial optical system blocks that include asymmetric aspherical off-axial reflecting surfaces and a plurality of prisms having refractive power. The off-axial optical system block having a surface may be a hollow type block composed entirely of a reflective surface as disclosed in JP-A-8-292371 and JP-A-8-292372.
[0081]
In addition, although the compound eye imaging device in which the convergence angle is changeable in the first embodiment and the baseline length can be changed in the second embodiment, both the convergence angle and the baseline length can be changed by combining these functions. Needless to say, a compound-eye imaging device may be configured.
[0082]
In addition, the imaging system in which the off-axial optical system block is used for the optical elements 11L, 11R, 12L, and 12R is shown. However, the degree of freedom of arrangement of the incident reference axis and the emission reference axis includes the off-axial optical system block. Therefore, any one of the optical elements 11L, 11R, 12L, and 12R may be replaced with a conventional coaxial optical system block.
[0083]
As described above, the left and right imaging systems include an asymmetric aspherical off-axial reflecting surface as a constituent element, and include at least one prism which is an off-axial optical system block having refractive power capable of forming a real image as a whole. Therefore, it is possible to provide a compact compound-eye imaging device that can set the convergence angle and the base line length relatively freely by taking advantage of the degree of freedom of the arrangement of the entrance reference axis and the exit reference axis of the off-axial optical system block. .
[0084]
In the first and second embodiments, the number of compound eyes is two for the sake of simplicity. However, an image used for three-dimensional display using a lenticular lens has more viewpoints. A set of images is required. In this case, a compound eye imaging device having three or more imaging systems is required, but in this case as well, it can be applied as in the case of two eyes.
[0085]
[Third Embodiment]
In the compound eye imaging apparatus according to the third embodiment, the left and right imaging systems are each configured by one off-axial optical element (off-axial optical system block). The off-axial optical elements 21R and 21L as imaging optical elements have an incident refracting surface, four asymmetric aspheric reflecting surfaces, and an exit refracting surface, and the light beam that has passed through the apertures 13R and 13L is used as an imaging device 14L such as a CCD. , 14R.
[0086]
As in the first and second embodiments, the off-axial optical elements 21R and 21L as the imaging optical elements do not have symmetry within the plane of the paper and have a rotationally asymmetric shape as a whole.
[0087]
Further, the optical element 21L has a symmetrical shape with the optical element 21R, and the same element as the optical element 21R is used upside down in the direction perpendicular to the paper surface as in the first and second embodiments.
[0088]
The optical elements 21R and 21L are made into an integral shape made of a transparent body by molding such as plastic or glass. It is the same as the optical elements 11R and 11L in the first and second embodiments that an optical system having a small left-right difference in imaging performance can be configured by molding. The optical elements 21R and 21L are rotatable around the centers 20R and 20L, respectively.
[0089]
FIG. 9 is a diagram illustrating an arrangement of off-axial optical elements 21R and 21L when the left and right imaging systems are used as a three-dimensional image capturing mode having a parallax. FIG. 10 is a diagram showing the arrangement of the off-axial optical elements 21R and 21L when used as a panoramic mode in which the viewpoints of the left and right imaging systems are substantially matched. In order to simplify the explanation, only the reference axis light beam, which is the light path of the light beam passing through the center of the image and the center of the stop, is drawn with a one-dot chain line.
[0090]
In general, when the off-axial optical system is a front aperture type in which the aperture is provided closest to the subject, the imaging system can be easily configured compactly. Such a front-aperture type imaging system is an imaging system suitable for the panoramic mode by matching the positions of the left and right entrance pupils. Therefore, by using a front-aperture type off-axial optical system block, a compound eye imaging apparatus capable of panoramic mode imaging, which was difficult to configure with a coaxial optical system, can be configured compactly.
[0091]
The two shooting modes are switched by rotating them around the centers 20R and 20L so that the relative positional relationship between the aperture, the off-axial optical system block (off-axial optical element), and the image sensor does not change. Done. By switching between these two photographing modes, a compound camera with higher added value can be provided.
[0092]
In the third embodiment, the optical elements 21R and 21L are asymmetric aspherical off-axial reflecting surfaces and prisms having a plurality of refractive powers. However, as an off-axial optical system block having an off-axial reflecting surface, As shown in JP-A-8-292371 and JP-A-8-292372, it may be a hollow type block that is entirely constituted by a reflective surface.
[0093]
[Fourth Embodiment]
FIG. 11 is a diagram illustrating an arrangement of an imaging system including an off-axial optical element in the fourth embodiment. This imaging system is an imaging system dedicated to the panorama mode, and has substantially the same configuration as that in FIG.
[0094]
In the fourth embodiment, the left and right imaging systems are each composed of one off-axial optical element (off-axial optical system block). The off-axial optical elements 31R and 31L as imaging optical elements are composed of an incident refracting surface, four asymmetric aspherical reflecting surfaces and an exit refracting surface. The images are formed on 14L and 14R. For the sake of simplicity, only the reference axis light beam, which is the light path of the light beam that passes through the image center and the stop center, is drawn with a one-dot chain line in the drawing.
[0095]
The off-axial optical elements 31R and 31L as the imaging optical elements have a rotationally asymmetric shape as a whole without having symmetry in the paper as in the case of the first and second embodiments. Further, the optical element 31L has a shape that is bilaterally symmetric with the optical element 31R, and the same element as the optical element 31R is used upside down in the direction perpendicular to the paper surface as in the third embodiment.
[0096]
The optical elements 31R and 31L are made into an integral shape made of a transparent body by molding such as plastic or glass. As in the case of the optical elements 11R and 11L in the first and second embodiments, it is possible to configure an optical system having a small difference in left and right imaging performance by molding.
[0097]
As described above, in general, in an off-axial optical system, if the front aperture type is provided where the aperture is located closest to the subject, the imaging system can be easily configured in a compact manner. The front aperture type imaging system is an imaging system suitable for a panoramic mode configuration in which the positions of the left and right entrance pupils coincide. Therefore, by using a front-aperture type off-axial optical system block, a compound eye imaging apparatus capable of panorama mode imaging, which is difficult to configure with a coaxial optical system, can be configured in a compact manner.
[0098]
Here, the feature of the compound eye imaging device of the fourth embodiment different from the third embodiment is that a trapezoidal distortion (distortion) asymmetric with respect to the imaging characteristics so that the image in the panoramic mode looks more natural. It is in having introduced.
[0099]
In general, in an off-axial optical system, an aspherical surface that is asymmetric to the left and right is mainly used as a reflecting surface. Accordingly, it is possible to easily generate a left-right asymmetric aberration that does not occur unless the coaxial optical system is rotationally symmetric. In that sense, it can be said that the off-axial optical system is an optical system suitable for a compound eye imaging system having a panoramic mode.
[0100]
FIG. 12 is a diagram conceptually showing an image obtained by photographing an object in front of the left and right imaging systems with an optical element having a trapezoidal distortion in imaging performance. When the trapezoidal distortion is not given to the imaging performance of the optical element, the square in front of the cubes “A” and “B” written in front of the left and right imaging systems in FIG. It is reflected as it is. On the other hand, by giving trapezoidal distortion to the left and right imaging characteristics so that the portion (center portion) connecting the images is shorter than the outside, the two images in FIG. The squares in front of which cubes “A” and “B” are written are recorded as images in a deformed form. When two images recorded in this deformed form are combined, a natural combined image is obtained as an image having an apparent central viewpoint in the middle as shown in FIG.
[0101]
As described above, providing the trapezoidal distortion in the imaging performance of the left and right optical elements has an effect of apparently moving the central viewpoint.
[0102]
FIG. 13 is a diagram conceptually showing an image photographed in the panoramic mode with the left and right optical elements having a trapezoidal distortion in imaging performance. Due to the trapezoidal distortion in which the part connecting the images (center part) is shorter with respect to the outside, the center part is apparently long as in the conventional case (see FIG. 15) taken with an imaging system without distortion on both the left and right sides. Thus, an image that is apparently at the central viewpoint of the ideal composite image is obtained (FIGS. 13A and 13B). When these are connected, an image almost similar to the ideal composite image is obtained as shown in FIG.
[0103]
In the fourth embodiment, the number of compound eyes for synthesizing a panoramic image is set to two eyes for the sake of simplicity. In general, when synthesizing a longer image in the left-right direction, a compound eye imaging device in which three or more imaging optical systems are arranged can be considered in the same manner. In such a case, the trapezoidal distortion generated by the cameras arranged on the outside may be increased. When the number of imaging systems is an odd number, the middle imaging system may be a trapezoidal imaging system without distortion.
[0104]
In the fourth embodiment, the optical elements 31R and 31L are off-axial optical blocks including asymmetric aspherical off-axial reflecting surfaces and prisms having a plurality of refractive powers. However, the optical elements 31R and 31L are off-axial reflecting surfaces having off-axial reflecting surfaces. The axial optical system block may be a hollow block composed entirely of a reflective surface as disclosed in JP-A-8-292371 and JP-A-8-292372.
[0105]
【The invention's effect】
As mentioned above,Main departureClearlyAccording toSymmetrical and left / rightAn off-axial optical system block including an asymmetric aspherical off-axial reflecting surface and having a refractive power for forming a real image as a whole;Left and rightFor each imaging system, So that the left and right imaging systems are upside downSince it is provided, the components of each imaging system can be reduced, and a compact configuration can be realized. Further, even if the distance between the image pickup elements is shortened, the base line length that is the distance between the apertures can be increased, and even when congestion is applied, mutual optical elements can be prevented from interfering with each other.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration of a compound eye imaging apparatus according to a first embodiment.
FIG. 2 is a diagram showing a configuration of a camera head unit 10;
FIG. 3 is a diagram showing the shape of an optical element 11R on the object side.
FIG. 4 is a diagram illustrating the shape of an image-side optical element 12R.
FIG. 5 is a diagram showing the arrangement of the left and right imaging systems and the optical path when the subject is at a long distance.
FIG. 6 is a diagram showing the arrangement of the left and right imaging systems and the optical path when the subject is at a short distance.
FIG. 7 is a diagram illustrating a configuration of a compound eye imaging apparatus according to a second embodiment.
FIG. 8 is a diagram showing an optical arrangement with a short base line length.
FIG. 9 is a diagram illustrating an arrangement of off-axial optical elements 21R and 21L when the left and right imaging systems are used as a three-dimensional image capturing mode having a parallax.
FIG. 10 is a diagram showing the arrangement of off-axial optical elements 21R and 21L when used as a panoramic mode in which the viewpoints of the left and right imaging systems are substantially matched.
FIG. 11 is a diagram illustrating an arrangement of an imaging system including an off-axial optical element in the fourth embodiment.
FIG. 12 is a diagram conceptually showing an image obtained by photographing an object in front of the left and right imaging systems with an optical element having a trapezoidal distortion in imaging performance.
FIG. 13 is a diagram conceptually showing an image photographed in a panoramic mode by left and right optical elements having a trapezoidal distortion in imaging performance.
FIG. 14 is a diagram illustrating a configuration of an imaging system in a conventional compound eye imaging apparatus.
FIG. 15 is a diagram conceptually showing an image when panorama shooting is performed with congestion on a conventional imaging system.
[Explanation of symbols]
10, 10A compound eye camera head
11L, 11R, 12L, 12R, 21L, 21R, 31L, 31R Optical element
13L, 13R, 13 Aperture
14L, 14R Image sensor
18L, 18R Cam groove
20 Signal processor

Claims (12)

In the compound-eye imaging device having left and right imaging system, the vertical symmetry and asymmetry aspheric off comprises axial reflecting surfaces, the off-axial optical system block having a refractive power for imaging a real image as a whole, of the left and right imaging system A compound eye imaging apparatus , wherein each of the left and right imaging systems has an upside-down relationship . The off-axial optical system block claim 1 Symbol placement compound-eye imaging device characterized by Tei Rukoto made by molding. The left and right image pickup system according to claim 1 Symbol placement compound-eye imaging apparatus, characterized in that to generate a trapezoidal distortion of the left and right opposite to imaged. In the imaging system, the compound-eye imaging apparatus according to any one claims 1 to 3, characterized in that the entering reference axis and the emergent reference axis is not on the same straight line. The compound-eye imaging apparatus according to any one of claims 1 to 4, wherein the imaging system has a stop immediately before the object-side entrance surface. 6. The compound-eye imaging apparatus according to claim 5 , further comprising a stop in front of the object-side entrance surface of the off-axial optical system block. The off-imaging system including an axial optical system block, the compound-eye imaging apparatus according to any one of claims 1 to 6, characterized in that at least one imaging in the middle of the optical path to the imaging surface. The off by rotating part or all of the imaging system including an axial optical system block, multi-lens imaging apparatus according to claim 1, wherein changing the convergence angle of the right and left imaging systems. By changing the angle of convergence of the left and right imaging system, characterized in that the left and right imaging system to switch the three-dimensional image photographing mode having a parallax, and a panorama mode which substantially matched the viewpoint of the left and right imaging system The compound eye imaging device according to claim 8 . The compound-eye imaging apparatus according to claim 9 , wherein a part or the whole of the imaging system including the off-axial optical system block is rotatable in a plane including an emission reference axis of the off-axial optical system block. . In a compound eye imaging device having left and right imaging systems, each of the left and right imaging systems includes an off-axial optical system block that includes asymmetric aspherical off-axial reflecting surfaces and has a refractive power for forming a real image as a whole. , for at least one of the left and right imaging system including the off-axial optical system block, by pivoting the some or all of their, you and changes the base line length of the imaging system of the right and left double Eye imaging device. The compound-eye imaging apparatus according to claim 11 , wherein a part or the whole of the imaging system including the off-axial optical system block is rotatable around an emission reference axis of the off-axial optical system block.

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