Radiation-proof camera

Abstract

To realize a higher resistance to radiation and a wider field of view in the front of a camera used under a high-radiation environment.SOLUTION: A radiation-proof camera includes: a convex curve mirror for reflecting light from an object; an imaging optical system for forming light from the object reflected by the convex curve mirror into an image; an imaging element for taking an image of the formed image; and a shielding unit for shielding radiation. The shielding part has an opening for passage of light which enters the imaging optical system. The convex curve mirror has the capability of shielding radiation.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a radiation-tolerant camera. [Background technology]

[0002] Cameras used for grasping the surroundings of robots in high radiation environments and for remote monitoring of various tasks must be both radiation-resistant and have a wide field of view. For more advanced tasks, it is also necessary to obtain distance information in addition to image information.

[0003] Patent Documents 1 and 2 disclose an imaging device in which a concave mirror and a radiation shield are placed in front of the camera to ensure radiation resistance of the front side of the camera, and the image reflected by the concave mirror is captured.

[0004] Patent Documents 3 and 4 disclose an imaging device in which three hyperbolic mirrors are arranged opposite each other and a camera is placed inside one of the hyperbolic surfaces. Images from two viewpoints reflected by the three hyperbolic mirrors are captured by the single camera, forming a stereo camera that can capture images in all directions, 360 degrees around, and measure distances. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2001-285690 [Patent Document 2] Patent Publication No. 2015-102357 [Patent Document 3] Patent No. 4388530 [Patent Document 4] Patent No. 7043375 Summary of the Invention [Problem to be solved by the invention]

[0006] The above-mentioned Patent Document 1 does not describe the shape of the reflector, but from the description and diagram of a reflecting telescope, it can be inferred that the shape of the reflector is concave. The above-mentioned Patent Document 2 describes the reflector as a concave mirror. In both cases, while the radiation resistance of the front of the camera is ensured by a shield, there is a problem that a wide field of view cannot be ensured because the reflector is concave.

[0007] In the above-mentioned Patent Documents 3 and 4, a hyperbolic mirror is used to ensure a wide field of view and also to obtain distance information, but there is no description of the shape or material of the mirror other than the reflective surface, and there is a problem that the camera is not radiation-resistant.

[0008] The present invention has been made in consideration of these circumstances, and has an object to provide a radiation-resistant camera that achieves both improved radiation resistance and a wide field of view by installing a convex curved mirror with shielding performance in front of the camera. [Means for solving the problem]

[0009] The present invention includes a number of means for solving the above problems, examples of which are as follows: In order to solve the above problems, the radiation-resistant camera of the present invention includes an imaging optical system that forms an image from light rays from a subject, an imaging element that captures the image formed by the imaging optical system, and a shielding section that covers the periphery of an imaging section including the imaging optical system and blocks radiation, further including a convex curved mirror that reflects light rays from the subject, the shielding section having at least an opening through which light rays reflected by the convex curved mirror and incident on the imaging optical system pass, and the convex curved mirror has the ability to block radiation. Effect of the Invention

[0010] According to the present invention, it is possible to realize a radiation-resistant camera that is both radiation-resistant and has a wide field of view.

[0011] Problems, configurations and effects other than those described above will become apparent from the following description of the embodiments. [Brief description of the drawings]

[0012] [Figure 1] 1 is a block diagram showing an example of the configuration of a camera system including a radiation-resistant camera according to a first embodiment of the present invention. [Diagram 2] FIG. 1 is a diagram showing a reference example for explaining problems with the conventional technology of a radiation-resistant camera used in a high radiation environment. [Diagram 3] FIG. 2 is an embodiment for explaining the principle of the present invention, showing the positional relationship between a convex curved mirror, an imaging unit, and a shielding unit in a radiation-resistant camera. [Figure 4] 3 is a diagram showing the positional relationship between radiation incident on an imaging optical system and a convex curved mirror in the first embodiment of the present invention. FIG. [Diagram 5] FIG. 2 is a diagram showing a radiation-resistant camera in the first embodiment of the present invention, in which a hyperboloid shape is adopted for the reflecting surface of a convex curved mirror. [Figure 6] FIG. 2 is a diagram showing the shape of convex curved mirror 12 in the first embodiment of the present invention when the mirror is required to have a certain level or higher of blocking radiation from within the field of view of imaging section 10. [Figure 7] FIG. 4 is a diagram illustrating the thickness of a convex curved mirror using specific numerical examples in the first embodiment of the present invention. [Figure 8] FIG. 2 is a diagram showing the thickness of the convex curved mirror in the y-axis direction calculated under specified conditions as a function of radius in the first embodiment of the present invention. [Figure 9] FIG. 11 is a block diagram showing an example of a camera system including a radiation-resistant camera according to a second embodiment of the present invention. [Figure 10] FIG. 4 is a diagram showing a radiation-resistant camera according to a second embodiment of the present invention. [Figure 11] FIG. 11 is a diagram showing an example of an image based on a captured image signal according to the second embodiment of the present invention. [Figure 12] FIG. 13 is a diagram showing a radiation-resistant camera according to a third embodiment of the present invention. [Figure 13] FIG. 11 is a diagram showing an example of an image based on a captured image signal according to the third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a number of embodiments of the present invention will be described with reference to the drawings.

[0014] [First embodiment] 1 is a block diagram showing an example of the configuration of a camera system including a radiation-resistant camera 1 according to a first embodiment of the present invention. The radiation-resistant camera 1 of this embodiment is mounted on, for example, a remote-controlled robot that operates in a high radiation environment, and is intended to grasp the situation around the robot by acquiring images with a wide field of view. The radiation-resistant camera 1 may also be intended to remotely monitor various tasks in a high radiation environment.

[0015] In general, an image captured by the radiation-resistant camera 1 is transmitted to an image processing unit 11 such as a CPU (Central Processing Unit) that executes detection of an object from the image and the like. The radiation-resistant camera 1 is communicatively connected to the image processing unit 11, for example, directly via a cable or via a communication network, and outputs information such as the captured image to the image processing unit 11. The image processing unit 11 may be mounted on the robot, or may be located in a building from which the robot is remotely operated.

[0016] The radiation-resistant camera 1 includes an imaging unit 10. As described below, the imaging unit 10 includes an imaging optical system 100 (see FIG. 3) and an imaging element 101 (same), and is, for example, a monocular camera. The imaging unit 10 generates an image signal 50 based on received light, and outputs it to an input I / F (interface) 110 of the image processing unit 11.

[0017] The image processing unit 11 is a unit that performs image processing on the captured image signal 50 output from the imaging unit 10. The image processing unit 11 includes an input I / F 110, a correction unit 111, and an output I / F 113.

[0018] Each component of the image processing unit 11 may be realized by a circuit, or at least a part of it may be realized by a processor such as a CPU that executes a program and a memory.

[0019] The input I / F 110 includes, for example, an A / D (analog / digital) converter, converts the captured image signal 50 output from the imaging unit 10 into a digital signal, and outputs it to a correction unit 111 at the downstream side.

[0020] The correction units 111 perform various image processing on the captured image signals 50 output from the input I / F 110 to correct the signals, and output the corrected signals to the output I / F 113. The image processing performed by the correction units 111 is, for example, a general-purpose geometric transformation, which can convert a distorted captured image into a predetermined coordinate system. The image processing performed by the correction units 111 may also include other processing, such as demosaicing.

[0021] The output I / F 113 outputs the corrected captured image signal 51 output from the correction unit 111 to a downstream control unit such as a CPU or ECU.

[0022] FIG. 2 is a diagram showing a reference example for explaining the problems of the conventional technology of a radiation-resistant camera used in a high radiation environment. The radiation-resistant camera 91 of the reference example shown in FIG. 2 is composed of an imaging unit 910 that acquires an image signal 50 of a subject and a shielding unit 920 that has radiation shielding properties. The imaging unit 910 is, for example, the monocular camera described above. The shielding unit 920 is arranged to surround the imaging unit 910 in order to shield radiation from the imaging unit 910. The shielding unit 920 has a partial opening 901 so as not to interfere with imaging by the imaging unit 910. In this case, among the radiation heading toward the radiation-resistant camera 91, radiation from approximately outside the field of view of the imaging unit 910 is shielded by the shielding unit 920. This shielding unit 920 can be easily realized by, for example, a metal material such as lead having a sufficient thickness. In addition, the field of view 930 of an image that can be acquired by the radiation-resistant camera 91 is determined by the focal length of the imaging optical system 9100 and the size of the imaging element 9101. The angle of view of the field of view 930 of the radiation-resistant camera 91 is, for example, about 40°.

[0023] Next, the problem to be solved by the present invention will be described. In the above-mentioned reference example, the shielding performance against radiation from approximately outside the range of the visual field of the imaging unit 910 is ensured by the shielding unit 920. On the other hand, radiation from within the range of the visual field 930 of the imaging unit 910 passes through the imaging optical system 9100 and reaches the imaging element 9101. This radiation shortens the life of the imaging element 9101 and increases the noise in the imaging image signal 50 acquired by the imaging unit 910. Although radiation from the front of the camera passes through the imaging optical system 9100, generally, the imaging optical system 9100 does not shield the radiation. This is because the imaging optical system 9100, which is generally used in a high radiation environment, is a non-browning lens made of, for example, quartz glass, and while discoloration due to radiation is suppressed, it has almost no shielding performance against radiation.

[0024] Furthermore, the radiation-resistant camera 91 of the reference example has a problem that it can only capture images in front of the camera and has a narrow field of view. For example, when used to grasp the surroundings of a work robot, it is not possible to check the entire surroundings of the robot at once, resulting in blind spots. Also, for self-location estimation and environmental map creation (SLAM) in robot control, the narrow field of view can cause the robot to lose track of its own location or reduce the efficiency of map creation.

[0025] Therefore, in the present invention, a convex curved mirror 12 (see Figure 3) with shielding properties is installed within the field of view of the imaging unit 10, and radiation from within the field of view of the imaging unit 10 is blocked, thereby improving resistance to radiation, while the field of view is expanded by photographing the subject reflected by the convex curved mirror 12.

[0026] FIG. 3 is an embodiment for explaining the principle of the present invention, and is a diagram showing the positional relationship between the convex curved mirror 12, the image capturing section 10, and the shielding section 20 in the radiation-resistant camera 1. In FIG.

[0027] 3, the radiation-resistant camera 1 of this embodiment includes an imaging optical system 100 that forms an image from light rays from a subject, an image sensor 101 that captures the image formed by the imaging optical system 100, and a shielding section 20 that covers the periphery of the imaging section 10 including the imaging optical system 100 and blocks radiation, and further includes the above-mentioned convex curved mirror 12 that reflects light rays from the subject, the shielding section 20 has at least an opening 201 through which light rays reflected by the convex curved mirror 12 and incident on the imaging optical system 100 pass, and the convex curved mirror 12 has the ability to block radiation.

[0028] Light rays from a subject heading toward the convex curved mirror 12 are reflected by the convex curved mirror 12, head toward the entrance pupil 1001 of the imaging optical system 100, and enter the imaging unit 10. The range of light rays entering the imaging unit 10, and therefore the range of the field of view 30 of the radiation-resistant camera 1, is as shown in FIG. 3. As shown in this figure, at least a part of the field of view that the imaging unit 10 alone can have (the field of view of the part where the convex curved mirror 12 is located) is reduced, while the field of view expands in a direction perpendicular to the optical axis of the imaging unit 10. For example, consider a case where the reflecting surface of the convex curved mirror 12 has an axially symmetric shape that conforms to a paraboloid, the axis of symmetry is aligned with (i.e., coaxial with) the optical axis of the imaging unit 10, and the radiation-resistant camera 1 is installed with the convex curved mirror 12 on top and the optical axis perpendicular to the surface as shown in the figure. At that time, this radiation-resistant camera 1 has an equal field of view in the entire horizontal direction, 360° around the optical axis, and the vertical angle of view can be adjusted by the shape of the reflecting surface of the convex curved mirror 12. Depending on the angle of the reflecting surface of the convex curved mirror 12, it is possible to widen the upper end of the angle of view above the horizontal and the lower end of the angle of view almost directly below. The maximum value of the upper end of the angle of view is realized when light rays enter the imaging unit 10 along a tangent to the surface of the convex curved mirror 12. The maximum value of the lower end of the angle of view is determined by the size of the imaging unit 10 and the shielding unit 20.

[0029] The convex curved mirror 12 is fixed to the imaging unit 10 and the shielding unit 20 by a support member 61 having a side portion in the form of a cylinder 60 made of, for example, quartz glass that transmits visible light and is not easily discolored by radiation. The shape of the side portion of the support member 61 is not limited to a cylinder, and may be a sphere, for example. When the side portion is a sphere, the effects of reflection and distortion caused by the glass can be reduced by aligning the center with the entrance pupil 1001 of the imaging optical system 100.

[0030] FIG. 4 shows the positional relationship between the radiation incident on the imaging optical system 100 and the convex curved mirror 12. In the imaging unit 10, radiation other than that incident on the entrance pupil 1001 of the imaging optical system 100 from within the field of view can be easily blocked by the shielding unit 20 so as not to affect imaging. An example of a part (hereinafter sometimes referred to as a shielding object) that is affected by the radiation that is not shielded as described above is the imaging element 101. In FIG. 4, the incidence range of radiation to be shielded when it is desired to reduce radiation damage to the entire surface of the imaging element 101 is shown by the left maximum incidence angle and the right maximum incidence angle. In this example, the radiation incidence range is determined by the relative positional relationship between the left and right ends of the shielding object and the left and right ends of the opening 201 of the shielding unit 20. In this way, this radiation incidence range is determined by the size of the shielding object whose damage is to be reduced and the opening 201 of the shielding unit 20, and the relative positional relationship between them. The size of the convex curved mirror 12 is set to include the radiation incidence range, so that it is possible to block radiation from within the field of view of the imaging unit 10.

[0031] The convex curved mirror 12 is made of a metal material such as lead or tungsten to provide shielding performance. If necessary, the reflective surface is mirror-finished with a metal coating such as aluminum coating.

[0032] The reflecting surface of the convex curved mirror 12 may have any shape as long as it is a convex curved shape that can obtain the effect of expanding the field of view. Examples of shapes include the above-mentioned paraboloid, as well as a non-axisymmetric free convex surface, a quadratic surface such as a hyperboloid, and the like. When a paraboloid is used, light rays approaching the focal point are reflected by the convex curved mirror 12 so as to be parallel to the paraboloid symmetry axis. In this case, by using a telecentric lens as the imaging optical system 100, an image signal 50 of orthogonal projection with the focal position as the viewpoint can be obtained. When a non-axisymmetric free convex surface is used, the field of view can be designed with a high degree of freedom. When a hyperboloid is used, as described later, light rays approaching the inner focal point are reflected by the convex curved mirror 12 so as to be directed toward the outer focal point. In this case, by matching the entrance pupil of the imaging optical system 100 with the outer focal point, an image signal 50 of perspective projection with the inner focal point as the viewpoint can be obtained.

[0033] The degree of distortion of the captured image signal 50 that can be obtained varies depending on the shape of the convex curved surface that is adopted, but the distorted captured image signal 50 can be converted into a captured image signal 50 in a specified coordinate system by a geometric transformation in the correction unit 111.

[0034] FIG. 5 is a diagram showing a radiation-resistant camera in the first embodiment of the present invention in which a hyperboloid shape is adopted for the reflecting surface of the convex curved mirror 12. In FIG.

[0035] Due to the nature of a hyperboloid, a light ray heading toward the inner focal point of the hyperboloid is reflected by the hyperboloid and heads toward the outer focal point. For example, when the outer focal point 121 of the convex curved mirror (hyperbolic mirror) 12 is installed so as to substantially coincide with the position of the entrance pupil 1001 of the imaging unit 10, a light ray heading toward the inner focal point 120 of the convex curved mirror 12 is reflected by the convex curved mirror 12 and heads toward the entrance pupil 1001, and enters the imaging unit 10, so that an image signal 50 having the inner focal point 120 of the convex curved mirror 12 as a viewpoint is acquired.

[0036] In the above, the arrangement of the convex curved mirror 12 has been described, assuming that the image sensor 101 is an object to be blocked, taking into consideration only the presence or absence of blocking, without considering the blocking rate.

[0037] Next, the radiation shielding performance (shielding ability) of the convex curved mirror 12 will be considered.

[0038] In the present invention, the shielding unit 20 and the convex curved mirror 12 together have a shielding capacity of a predetermined value or more in all directions in three-dimensional space. The predetermined value is determined from the surrounding radiation dose distribution, the position and size of the shielded object in the imaging unit 10, and the allowable cumulative dose of the shielded object. For example, if it is assumed that the radiation dose distribution is constant in all directions, the radiation needs to pass through, for example, a sufficient thickness of lead so that it is shielded at a certain value or more in all directions toward the shielded object. The required shielding amount is determined from the surrounding radiation dose and the allowable cumulative dose of the shielded object.

[0039] FIG. 6 is a diagram showing the shape of the convex curved mirror 12 in the first embodiment when the mirror is required to have a certain level of blocking performance against radiation from within the field of view of the imaging section 10. In FIG.

[0040] For example, consider a case where radiation toward the imaging element 101 is shielded at a certain level or more. In order to provide a certain level or more of shielding performance, radiation heading toward the imaging element 101, which is the object to be shielded, needs to pass through the convex curved mirror 12 at a certain distance or more. Here, if the size of the imaging element 101 is smaller than the size of the opening 201 or the distance to the opening 201, it is possible to approximate the imaging element 101 as a point. At this time, for all radiation that passes through the opening 201 and enters the imaging element 101, the convex curved mirror passing distance 40 needs to be a certain value or more. At that time, the shape of the reflecting surface and the back surface of the convex curved mirror 12 may be different. Here, the case where the imaging element 101 can be approximated as a point has been described, but if the object to be shielded has a size, the thickness of the convex curved mirror 12 required at each point of the object to be shielded is calculated, and the final thickness of the convex curved mirror 12 may include the thickness calculated for each point. Of course, it is also possible to manufacture it thicker than that, taking into account workability and the like.

[0041] FIG. 7 is a diagram illustrating the thickness of the convex curved mirror 12 using specific numerical examples.

[0042] For example, consider the case where radiation (gamma rays from cobalt 60) reaching the imaging element 101 is to be shielded to 1 / 10 and the convex curved mirror 12 is made of lead, for example. In this case, in order for the radiation to be shielded sufficiently, it needs to travel 40 mm or more through the lead. Also consider the case where the reflecting surface of the convex curved mirror 12 is an axially symmetric hyperboloid expressed by the following formula (1), for example, where a=20 mm, b=30 mm, and the radius of the reflecting surface is 30 mm.

[0043]

number

[0044] 7, it is assumed that the image sensor 101 is located at the origin, and the entrance pupil 1001 of the imaging optical system 100 is located at, for example, x = 0 mm, y = 10 mm. For example, if the entrance pupil 1001 and the outer focal point 121 of the convex curved mirror 12 are aligned, the apex of the convex curved mirror 12 is located at y = 76.1 mm, a further distance (focal length + a) in the y direction. The rear surface shape of the convex curved mirror 12 is expressed by the following equation (2) using the incidence angle θ as a parameter.

[0045]

number

[0046] In formula (2),

[0047]

number

[0048] Here, x and y are positions perpendicular and parallel to the optical axis, respectively, with the image sensor 101 as the origin, and satisfy the relationship y / x=tan θ, l is the thickness required for shielding, and s is the distance between the image sensor 101 and the entrance pupil 1001, which is determined by the imaging optical system 100.

[0049] FIG. 8 is a diagram showing the thickness of the convex curved mirror 12 in the y-axis direction calculated under the above conditions as a function of radius.

[0050] As mentioned above, the convex curved mirror 12 is made of a heavy metal material that blocks radiation. When mounting this radiation-resistant camera 1 on a robot or the like, it is desirable for the weight to be light in order to facilitate smooth operation. Therefore, if the side surface of the convex curved mirror 12 is shaped in accordance with the angle of incidence of radiation as shown in Fig. 6, the convex curved mirror 12 can have sufficient shielding performance while being lightweight.

[0051] The first embodiment of the present invention has been described above. According to the first embodiment, by installing the convex curved mirror 12 with shielding performance within the field of view of the imaging unit 10, it is possible to realize a radiation-resistant camera 1 that has a wide field of view while providing radiation resistance to the front of the camera, which was difficult to shield with conventional technology.

[0052] The imaging unit 10 may be a combination of a lens, which is a refractive optical system, and an imaging element 101, or an optical system equivalent to a reflecting telescope in which a reflecting mirror is combined with the lens and the imaging element 101. The input I / F 110 has been described as including, for example, an A / D converter, but this A / D converter may be included in the imaging unit 10, for example. In this case, the input I / F 110 outputs a digital captured image signal 50 output from the imaging unit 10 to a correction unit 111 in a subsequent stage.

[0053] Convex curved mirror 12 does not need to have a shape symmetrical with respect to the optical axis, and may have, for example, a part of a quadratic curved surface or a hole as long as the curved surface is convex. In addition, the shape of the back surface of convex curved mirror 12 may be made thicker than the minimum thickness required for shielding as long as it is ensured, or the back surface may be made flat while ensuring the minimum thickness in consideration of processability, etc.

[0054] The shielding portion 20 does not need to completely surround the imaging portion 10. Similar to the shielding capacity of the convex curved mirror 12 described above, the thickness of the shielding portion 20 may be changed depending on the location, or the shape may be limited to only the necessary portion, depending on the radiation dose distribution around the shielding portion 20, the position and size of the object to be shielded by the imaging portion 10, and the allowable cumulative dose of the object to be shielded.

[0055] The shapes of the convex curved mirror 12, imaging unit 10, and shielding unit 20 shown in the figure, the parameters of the hyperbolic mirror shown in this embodiment, and the position of the entrance pupil 1001 are merely examples, and other parameters may be used as long as they do not deviate from restrictions such as the mirror being a convex curved surface.

[0056] As an example of installation in this embodiment, a case has been shown in which the convex curved mirror 12 is on top with the optical axis vertical, but it is also possible to, for example, have it upside down or have the optical axis horizontal.

[0057] In this embodiment, the reduction of damage to the image sensor 101 is taken into consideration, but damage to other objects to be shielded may also be taken into consideration. In the example shown in Fig. 7, the required shielding ratio is set to 1 / 10, but other shielding ratios may also be taken into consideration. The type of radiation assumed is gamma rays from cobalt 60, but other types of radiation may also be used.

[0058] [Second embodiment] In the first embodiment, it is assumed that the radiation-resistant camera 1 acquires the captured image signal 50 from one viewpoint. In this embodiment, the imaging unit 10 simultaneously acquires captured image signals 50 from two viewpoints, and uses these signals to also perform distance measurement by stereoscopic vision. That is, in this embodiment, in addition to the image (light beam) of the subject reflected by the convex curved mirror 12, the imaging unit 10 widens the angle of view of the imaging optical system 100 to directly include the image (light beam) of the subject in the field of view, and also acquires a direct image of the subject.

[0059] 9 is a block diagram showing an example of a camera system including a radiation-resistant camera 1 according to a second embodiment of the present invention. The radiation-resistant camera 1 of this embodiment is mounted on, for example, a remote-controlled robot that operates in a high radiation environment, and is intended to grasp the situation around the robot by acquiring wide-field-of-view distance information in addition to wide-field-of-view images. The radiation-resistant camera 1 may be intended to remotely monitor various tasks in a high radiation environment based on images and distance information.

[0060] The difference from the first embodiment in FIG. 9 is that a stereo processing unit 112 is present between the correction unit 111 and the output I / F 113. When the imaging unit 10 acquires captured image signals 50 from two viewpoints, the correction unit 111 outputs two-viewpoint corrected captured image signals 51 that have been subjected to various image processing including distortion correction. The stereo processing unit 112 executes stereo processing using the two-viewpoint corrected captured image signals 51 as input, extracts distance information, and outputs distance image data 52 to the output I / F 113. The stereo processing unit 112 also outputs the corrected captured image signals 51 output from the correction unit 111 to the output I / F 113. The output I / F 113 outputs the corrected captured image signals 51 and the distance image data 52 to a control unit such as a CPU or ECU in a downstream stage.

[0061] FIG. 10 is a diagram showing a radiation-resistant camera 1 according to a second embodiment of the present invention. A case will be described in which a fisheye lens 16 with a viewing angle of 180° is used as an optical element with a wide viewing field for the imaging optical system 100 in the radiation-resistant camera 1 to obtain a direct image of a subject. The convex curved mirror 12 occupies at least a part of the viewing field range of the imaging unit 10. In this case, the captured image signal 50 acquired by the imaging unit 10 is generated from a light ray that is directly incident on the imaging optical system 100 from the fisheye lens 16 and a light ray that is reflected by the convex curved mirror 12 and then enters the imaging optical system 100. The captured image signal 50 generated from the former light ray has the entrance pupil 1001 of the imaging optical system 100 as a viewpoint, and the captured image signal 50 generated from the latter light ray has the vicinity of the convex curved mirror 12 as a viewpoint. In particular, for example, if the shape of the convex curved mirror 12 is a hyperboloid and the outer focus of the hyperboloid is approximately coincident with the entrance pupil 1001 of the imaging optical system 100, the viewpoint of the captured image signal 50 generated from the light reflected by the convex curved mirror 12 and entering the imaging optical system 100 will be the inner focus 120 of the convex curved mirror 12.

[0062] For example, as shown in FIG. 10, when a hyperbolic convex mirror 12 is arranged on the optical axis of the image capturing unit 10, the image captured by the image capturing unit 10 based on the captured image signal 50 has an image with the inner focus 120 of the convex mirror 12 as the viewpoint at the center of the image, and an image with the entrance pupil 1001 of the image capturing optical system 100 as the viewpoint at the outer edge of the image, as shown in FIG. 11. Here, it is assumed that the radiation-resistant camera 1 is installed with the convex mirror 12 on top and the optical axis vertical as shown in FIG. 10, and the arrow representing the subject is pointing vertically upward. In this way, it is possible to simultaneously acquire image information from two viewpoints on one captured image signal 50. The image information from the two viewpoints is processed at the input I / F 110 and subsequent steps as described above, and the distance image data 52 is output from the output I / F 113 together with the corrected captured image signal 51. Here, an example of the process of the stereo processing unit 112 that outputs the distance image data 52 is block matching. Block matching is a technique for calculating the difference in position (disparity) between images taken from two viewpoints for the same subject, and then calculating the distance to the subject from that disparity.

[0063] In this embodiment, the shape of the side surface of the support member 61 may be an ellipsoid instead of a cylinder 60. By matching the two focal points of the ellipsoid with the two viewpoints of the captured image signal 50 to be acquired, the effects of reflection and distortion due to the glass can be reduced. In this embodiment, the two viewpoints are the inner focal point 120 of the convex curved mirror 12 and the entrance pupil 1001.

[0064] The second embodiment of the present invention has been described above. According to the second embodiment, by installing the convex curved mirror 12 with shielding performance in front of the imaging unit 10 and maintaining the field of view of direct imaging by the imaging unit 10 (fisheye lens 16), it is possible to realize a radiation-resistant camera 1 that can obtain distance image data 52 by stereoscopic vision for some subjects in addition to the wide field of view and shielding of the front of the imaging unit 10 realized in the first embodiment.

[0065] Here, a fisheye lens 16 with a viewing angle of 180° is shown as an example of a wide-field optical element used in the imaging optical system 100. However, as long as the imaging unit 10 can obtain captured image signals 50 from two viewpoints of the same subject, there are no limitations on the value of the viewing angle or the projection method of the imaging optical system 100.

[0066] [Third embodiment] In the second embodiment, a light ray reflected by the convex curved mirror 12 and a light ray directly incident on the imaging unit 10 are captured, thereby simultaneously acquiring captured image signals 50 from two viewpoints with a single captured image signal 50. In this embodiment, a hyperbolic mirror is added to the radiation-resistant camera 1 of the first embodiment, thereby simultaneously acquiring captured image signals 50 from two viewpoints with a light ray reflected once by the convex curved mirror 12 and a light ray reflected twice by the additional mirror. In this embodiment, both a corrected captured image signal 51 and distance image data 52 are output based on the captured image signal 50, as in the second embodiment.

[0067] An example of a camera system including the radiation-resistant camera 1 according to this embodiment is the same as that shown in FIG. 9 and explained in the second embodiment, and therefore a description thereof will be omitted.

[0068] FIG. 12 is a diagram showing a radiation-resistant camera 1 according to a third embodiment of the present invention.

[0069] In this embodiment, the reflecting surface of the convex curved mirror 12 has a hyperbolic shape, the central axis of the convex curved mirror 12 approximately coincides with the optical axis of the imaging optical system 100, and the outer focal point 121 of the convex curved mirror 12 approximately coincides with the entrance pupil 1001 of the imaging unit 10. The radiation-resistant camera 1 of this embodiment also has a second convex curved mirror 13 and a third convex curved mirror 14 that share a common central axis with the convex curved mirror 12, and the reflecting surfaces of the second convex curved mirror 13 and the third convex curved mirror 14 also have a hyperbolic shape. Hereinafter, the convex curved mirror 12 may be referred to as the first hyperbolic mirror, the second convex curved mirror 13 as the second hyperbolic mirror, and the third convex curved mirror 14 as the third hyperbolic mirror.

[0070] The second hyperbolic mirror 13 is disposed so that its outer focal point 131 and the inner focal point 140 of the third hyperbolic mirror 14 approximately coincide with each other, and the outer focal point 141 of the third hyperbolic mirror 14 approximately coincides with the entrance pupil 1001 of the imaging unit 10. At this time, as described in the first embodiment, a light ray traveling toward the inner focal point 120 of the first hyperbolic mirror 12 is reflected by the first hyperbolic mirror 12 and enters the outer focal point 121 of the first hyperbolic mirror 12, that is, the entrance pupil 1001 of the imaging unit 10. Therefore, the viewpoint of the captured image signal 50 by this light ray is the inner focal point 120 of the first hyperbolic mirror 12. On the other hand, a light ray traveling toward the inner focal point 130 of the second hyperbolic mirror 13 is reflected by the second hyperbolic mirror 13 and enters the outer focal point 131, that is, the inner focal point 140 of the third hyperbolic mirror 14. This light ray is further reflected by the third hyperbolic mirror 14, proceeds toward the outer focal point 141 of the third hyperbolic mirror 14, i.e., the entrance pupil 1001 of the imaging optical system 100, and enters the imaging unit 10. Therefore, the viewpoint of the captured image signal 50 based on this light ray becomes the inner focal point 130 of the second hyperbolic mirror 13. An aperture 202 is provided in the second hyperbolic mirror 13 so that these light rays reflected by the first hyperbolic mirror 12 and the third hyperbolic mirror 14 enter the entrance pupil 1001.

[0071] For example, as shown in Fig. 12, when the first hyperbolic mirror 12, the second hyperbolic mirror 13, and the third hyperbolic mirror 14 are arranged on the optical axis of the imaging unit 10, the image based on the captured image signal 50 acquired by the imaging unit 10 will be, for example, an image with the inner focus 130 of the second hyperbolic mirror 13 as the viewpoint at the center of the image, and an image with the inner focus 120 of the first hyperbolic mirror 12 as the viewpoint at the outer edge of the image, as shown in Fig. 13. Here, as in Fig. 11, a case is considered in which the radiation-resistant camera 1 is installed with the first hyperbolic mirror 12 on top and the optical axis vertical, and the arrow representing the subject is assumed to point vertically upward. Therefore, as in the second embodiment, the captured image signals 50 from these two viewpoints are processed at the input I / F 110 and onwards, and distance image data 52 is output from the output I / F 113 together with the corrected captured image signal 51.

[0072] In this embodiment, the field of view of the corrected captured image signal 51 from each of the two viewpoints can be changed by adjusting the shapes of the convex curved mirrors 12, 13, and 14. In general, compared to the imaging optical system 100 including a wide-field optical element such as the fisheye lens 16 used in the second embodiment, the convex curved mirror 12 used in this embodiment can inexpensively and easily be adjusted to expand or adjust the field of view.

[0073] In addition, with regard to the shielding ability against the object to be shielded, the second convex curved mirror 13 and / or the third convex curved mirror 14 are provided with shielding ability, which, combined with the shielding ability of the convex curved mirror 12 and the shielding section 20, provides a shielding ability (shielding ability) of a predetermined value or more against radiation from all directions in three-dimensional space. As described above, the predetermined value of the predetermined shielding ability is determined according to the radiation dose distribution around the shielding section 20, the position and size of the object to be shielded, the allowable cumulative dose of the object to be shielded, etc.

[0074] The third embodiment of the present invention has been described above. According to the third embodiment, by installing the convex curved mirror 12 having a shielding performance in front of the imaging unit 10 and then installing the additional hyperbolic mirrors 13 and 14, it is possible to realize a wide field of view, shielding within the field of view of the imaging unit 10, and acquiring distance image data 52 for a part of the subject, as in the second embodiment. Furthermore, compared to the second embodiment, by using the convex curved mirrors 13 and 14 instead of the imaging optical system 100 including an optical element with a wide field of view, such as a fisheye lens 16, it is possible to adjust the field of view more easily and inexpensively.

[0075] Although the present invention has been described above using a number of embodiments, it is of course not limited to the above embodiments and includes various modifications.

[0076] In addition, the arrangement, dimensions, shape, and other configurations of the components of the radiation-resistant camera are not limited to the examples described or illustrated above, so long as the object of the present invention can be achieved. Furthermore, the terms expressing the relationship, position, direction, shape, and other aspects of the components, such as "horizontal," "vertical," "plane," "convex surface," and "hyperbolic surface," are not limited to their strict literal meanings, and may include cases where the terms have substantially the same meaning, so long as the object and effect of the present invention can be achieved.

[0077] The above-described embodiment has been described in detail to clearly explain the present invention, and is not necessarily limited to having all of the configurations described. Also, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment.

[0078] The present invention has been described in terms of mounting a radiation-resistant camera on a remote-controlled robot, but the invention can be embodied in various forms, such as being mounted on a vehicle that operates in a high radiation environment, or being fixedly installed in a high radiation environment, without being limited to robots. [Explanation of symbols]

[0079] 1...radiation-resistant camera, 10...imaging unit, 20...shielding unit, 30...field of view, 40...convex curved mirror passing distance, 50...captured image signal, 51...corrected captured image signal, 52...range image data, 60...cylinder, 11: image processing unit, 110: input I / F, 111: correction unit, 112: stereo processing unit, 113: output I / F, 100: imaging optical system; 101: imaging element; 201: aperture; 202: aperture; 1001: entrance pupil; 12...convex mirror (hyperbolic mirror, first convex mirror, first hyperbolic mirror), 120...inner focus of the first hyperbolic mirror, 121...outer focus of the first hyperbolic mirror, 16...Fisheye lens 13... second convex curved mirror (second hyperbolic mirror), 130... inner focus of the second hyperbolic mirror, 131... outer focus of the second hyperbolic mirror, 14...Third convex curved mirror (third hyperbolic mirror), 140...Inner focus of the third hyperbolic mirror, 141...Outer focus of the third hyperbolic mirror 91...radiation-resistant camera, 901...aperture, 910...imaging section, 920...shielding section, 930...field of view, 9100...imaging optical system, 9101...imaging element, 91001...entrance pupil

Claims

1. an imaging optical system that forms an image from light rays from a subject; an imaging element that captures the image formed by the imaging optical system; a shielding section that covers the periphery of an imaging section including the imaging optical system and shields from radiation, further comprising a convex curved mirror that reflects light rays from the subject, the shielding portion has an opening through which light rays reflected by at least the convex curved mirror and incident on the imaging optical system pass, The convex curved mirror has the ability to block radiation. A radiation-resistant camera characterized by:

2. 2. The radiation-resistant camera according to claim 1, the shielding portion and the convex curved mirror together have a shielding ability equal to or greater than a predetermined value in all directions in a three-dimensional space, The predetermined value is determined based on the radiation dose distribution in the surrounding area, the position and size of the shielded object in the imaging unit, and the allowable cumulative dose of the shielded object. A radiation-resistant camera characterized by:

3. 2. The radiation-resistant camera according to claim 1, The convex curved mirror has a reflecting surface in the shape of a quadratic curve. A radiation-resistant camera characterized by:

4. 2. The radiation-resistant camera according to claim 1, The convex curved mirror has a reflecting surface in the shape of a hyperboloid. A radiation-resistant camera characterized by:

5. 5. The radiation-resistant camera according to claim 4, the convex curved mirror has an outer focus of a hyperboloid that substantially coincides with the position of an entrance pupil of the imaging optical system; A light ray from the subject that is directed toward the inner focal point of the convex curved mirror is reflected by the convex curved mirror and directed toward the entrance pupil of the imaging optical system. A radiation-resistant camera characterized by:

6. 5. The radiation-resistant camera according to claim 4, The imaging optical system includes, in addition to the light beam from the subject reflected by the convex curved mirror, the light beam from the subject directly within the field of view. A radiation-resistant camera characterized by:

7. 6. The radiation-resistant camera according to claim 5, the convex curved mirror is formed as a first hyperbolic mirror whose central axis substantially coincides with the optical axis of the imaging optical system, The optical system further includes a second hyperbolic mirror and a third hyperbolic mirror that share a central axis with the first hyperbolic mirror, an outer focal point of the second hyperbolic mirror and an inner focal point of the third hyperbolic mirror substantially coincide with each other; an outer focal point of the third hyperbolic mirror and an entrance pupil position of the imaging optical system are substantially coincident; A light ray from the subject heading toward the inner focal point of the second hyperbolic mirror is reflected by the second hyperbolic mirror toward the inner focal point of the third hyperbolic mirror, and is further reflected by the third hyperbolic mirror toward the entrance pupil of the imaging optical system. A radiation-resistant camera characterized by:

8. 8. The radiation-resistant camera according to claim 7, the second hyperbolic mirror and / or the third hyperbolic mirror have the ability to block radiation; the shielding portion, the first hyperbolic mirror, the second hyperbolic mirror, and / or the third hyperbolic mirror collectively have a shielding ability equal to or greater than a predetermined value in all directions in a three-dimensional space, The predetermined value is determined based on the radiation dose distribution in the surrounding area, the position and size of the shielded object in the imaging unit, and the allowable cumulative dose of the shielded object. A radiation-resistant camera characterized by:

Images