Imaging device

Abstract

To provide an imaging device with which it is possible to obtain telescopic and wide-angle images with high resolution.SOLUTION: An imaging device (10) comprises: an imaging optical system (11) which is composed including a first optical member (111) having a semi-transmissive reflection surface and a second optical member (112) having a reflection surface; and an imaging element (12) for capturing an image that is formed via the imaging optical system, with a plurality of images differing in focal distance being formed on the same light receiving surface of the imaging element. The imaging device (10) may include a controller (13) for acquiring image signals from the imaging element (12) and separating the plurality of images by image processing.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an imaging device. [Background technology]

[0002] An imaging optical system that forms an image of an object to be observed has various physical properties such as focal length and angle of view. When the focal length is longer, an enlarged image of the object to be observed is formed, and detailed optical information of the object to be observed at a distance, in other words, enlarged optical information, can be obtained. As the angle of view becomes wider, optical information of the object to be observed located in a wider range can be obtained. However, there is a trade-off between focal length and angle of view, and as the focal length becomes longer, the angle of view becomes narrower, and as the focal length becomes shorter, the angle of view becomes wider.

[0003] Therefore, the focal length is adjusted so that desired optical information can be obtained according to the situation. For example, the focal length is adjusted by displacing a zoom lens included in the imaging optical system. Also, the focal length is adjusted by switching between a plurality of fixed focal length lenses (see Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-311832 [Patent Document 2] JP 2004-279556 A Summary of the Invention [Problem to be solved by the invention]

[0005] The techniques of Patent Documents 1 and 2 can obtain a telephoto image, which is an image captured at a distance, or a wide-angle image, which is an image captured at a wide angle of view, by switching the focal length. However, the techniques of Patent Documents 1 and 2 cannot obtain a telephoto image and a wide-angle image at the same time with high resolution.

[0006] In view of such circumstances, an object of the present disclosure is to provide an imaging device capable of obtaining a telephoto image and a wide-angle image with high resolution.

Means for Solving the Problems

[0007] An imaging device according to an embodiment of the present disclosure includes an imaging optical system including a first optical member having a semi-transmissive reflecting surface and a second optical member having a reflecting surface, and an image sensor that images an image formed through the imaging optical system. A plurality of images with different focal lengths are formed on the same light-receiving surface of the image sensor.

Advantages of the Invention

[0008] According to the present disclosure, it is possible to provide an imaging device capable of obtaining a telephoto image and a wide-angle image with high resolution.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

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Modes for Carrying Out the Invention

[0010] Hereinafter, an imaging device according to an embodiment of the present disclosure will be described with reference to the drawings. In the components shown in the following drawings, the same components are denoted by the same reference numerals. The drawings for explaining the embodiment are schematic. The dimensional ratios and the like on the drawings do not necessarily match the actual ones.

[0011] FIGS. 1 and 2 are diagrams illustrating the configuration of an imaging device 10 according to an embodiment. FIG. 1 is a block diagram illustrating a logical configuration. Further, FIG. 2 is a cross-sectional view showing the components arranged in the imaging device 10. First, an overview of the configuration of the imaging device 10 will be described. As shown in FIG. 1, the imaging device 10 according to an embodiment of the present disclosure includes an imaging optical system 11 and an imaging element 12. The imaging device 10 may further include a controller 13.

[0012] The imaging optical system 11 includes a first optical member 111 and a second optical member 112. The first optical member 111 and the second optical member 112 are each configured by combining one optical element or a plurality of optical elements. The optical element may be, for example, a lens, a mirror, or a diaphragm. The first optical member 111 has a semi-transmissive reflecting surface 111a. Further, the second optical member 112 has a reflecting surface 112a.

[0013] The imaging optical system 11 forms an image of the subject light beam that passes through the first optical member 111 and enters the imaging element 12. Further, the imaging optical system 11 forms an image of the subject light beam that is reflected by the reflecting surface 111a of the first optical member 111 and the reflecting surface 112a of the second optical member 112 and enters the imaging element 12. Hereinafter, the subject light beam may be simply expressed as light.

[0014] The imaging element 12 captures an image of an image formed on the light receiving surface 12a via the imaging optical system 11. The imaging element 12 may be capable of capturing an image with visible light, may be capable of capturing an image with invisible light such as infrared light or ultraviolet light, or may be capable of capturing an image with visible light and invisible light. The imaging element 12 is, for example, a CCD (Charge Coupled Device) image sensor, a CMOS (Complementary Metal-Oxide-Semiconductor) image sensor, or the like. The imaging element 12 may be a color image sensor. In other words, the plurality of pixels arranged on the light receiving surface 12a of the imaging element 12 may be covered with, for example, an RGB color filter. The imaging element 12 generates an image signal corresponding to the received image. The imaging element 12 may generate an image signal at a predetermined frame rate such as 30 fps, for example.

[0015] The controller 13 is configured to include at least one processor, at least one dedicated circuit, or a combination thereof. The processor is a general-purpose processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), or a dedicated processor specialized for specific processing. The dedicated circuit may be, for example, an FPGA (Field-Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), or the like. The controller 13 acquires an image signal from the imaging element 12 and performs image processing on the image signal. The image processing includes a process of separating a plurality of images. Details of the image processing will be described later.

[0016] Next, the arrangement of the components of the imaging device 10 will be described. Here, as shown in FIG. 2, the side where the subject exists with respect to the imaging device 10 may be expressed as the object side or the front. Also, the side opposite to the object side may be expressed as the image side or the rear. FIG. 2 shows a cross-sectional view of the imaging device 10 cut at the position where the imaging element 12 is included.

[0017] As shown in FIG. 2, the imaging optical system 11 is configured to include a Cassegrain optical system having a first optical member 111 as a primary mirror and a second optical member 112 as a secondary mirror. In the present embodiment, the reflecting surface 111a of the first optical member 111 is a concave mirror, and the reflecting surface 112a of the second optical member 112 is a convex mirror. Subject light beams from a distant subject are reflected by the reflecting surface 111a and directed toward the reflecting surface 112a (optical path L1), reflected by the reflecting surface 112a, and reach the imaging element 12 through the region R of the first optical member 111 (optical path L2). In the present embodiment, an image obtained by the subject light beams passing through the optical paths L1 and L2 and forming an image on the light receiving surface 12a is a telephoto image. Also, the region R is an aperture.

[0018] Further, the first optical member 111 has, on the image side, a lens 113 having a reflecting surface 111a that is semi-transmissive and an aperture (region R). The lens 113 is transparent but not limited to being transparent. In the present embodiment, the lens 113 is a so-called doughnut lens. However, the region R is not limited to an aperture as long as it does not obstruct the light from the secondary mirror of the above-described Cassegrain optical system to the imaging element 12. The lens 113 may include, for example, a lens having a different curvature in a portion of the region R from other portions, or may include a transparent plate, a filter, etc. in the region R. Subject light beams corresponding to a wide-angle image pass through the reflecting surface 111a and reach the imaging element 12 through the lens 113 (optical path L0). The curvature, etc. of the lens 113 are determined so that light forms an image on the light receiving surface 12a through the lens 113. The curvature of the reflecting surface 111a and the curvature of the image-side surface of the lens 113 may be different. That is, the curvatures of the front surface (reflecting surface 111a) and the back surface 111b of the first optical member 111 do not have to be the same. Here, the wide-angle image only needs to be one that captures a wider angle of view than the telephoto image and is not limited to an image with a specific angle of view or more. Also, the telephoto image only needs to have a higher image magnification than the wide-angle image and is not limited to an image with a specific image magnification or more.

[0019] At the same time that the subject light beam corresponding to the telephoto image reaches the imaging device 12 through the optical path L1 and the optical path L2, the subject light beam corresponding to the wide-angle image also reaches the imaging device 12 through the optical path L0. Then, a plurality of images are formed on the light receiving surface 12a, that is, an image formed through the Cassegrain optical system and an image formed through the lens 113 without passing through the second optical member 112 which is the secondary mirror. In other words, a plurality of images with different focal lengths are formed on the same light receiving surface 12a of the imaging device 12.

[0020] Here, as shown in FIG. 2, another lens 114 may be provided on the object side surface of the second optical member 112. The another lens 114 may also function as a support portion for fixing the position of the second optical member 112.

[0021] FIG. 3 is a diagram for explaining the superimposed image olim and the telephoto image im1 and the wide-angle image im2 generated from the superimposed image olim. In the example of FIG. 3, the telephoto image im1 corresponds to an image obtained by imaging a subject on a distant road at the center portion of the wide-angle image im2 with high resolution. The image formed on the light receiving surface 12a is the superimposed image olim (the upper figure in FIG. 3) of the telephoto image im1 and the wide-angle image im2. The superimposed image olim includes the optical information of the telephoto image im1 and the wide-angle image im2. The imaging device 12 generates an image signal of the superimposed image olim and outputs it to the controller 13.

[0022] The controller 13 separates the superimposed image olim into the telephoto image im1 and the wide-angle image im2 by image processing. The controller 13 separates the superimposed image olim by applying an image processing method such as independent component analysis, wavelet method, image separation model, etc. The image separation model is, for example, a model constructed by creating a superimposed image in which a plurality of images are superimposed in advance and performing machine learning on the superimposed image with the plurality of images as the correct answers. The image separation model may be a model to which Pix-to-Pix is applied, which competes a generator that generates an image such as an Encoder-Decoder model and a discriminator that determines whether the generated image is a fake image, and generates a pair image reflecting the relationship.

[0023] Here, when the controller 13 executes image processing for separating an image using an image separation model previously constructed by machine learning, the image separation model may be stored in a storage unit accessible by the controller 13. The storage unit is one or more memories. The memory may be, for example, a semiconductor memory, a magnetic memory, etc., but is not limited thereto and can be any memory. The storage unit may be, for example, built into the controller 13 or provided outside the controller 13.

[0024] FIG. 4 is a flowchart for explaining the image processing executed by the controller 13. In the present embodiment, the controller 13 separates the superimposed image olim into a telephoto image im1 and a wide-angle image im2 using an image separation model previously constructed by machine learning.

[0025] The controller 13 acquires an image signal of the superimposed image olim from the image pickup device 12 (step S1).

[0026] The controller 13 separates the telephoto image im1 by extracting components determined to be the telephoto image im1 from the image signal of the superimposed image olim using the image separation model (step S2).

[0027] The controller 13 separates the wide-angle image im2 by subtracting the components of the telephoto image im1 from the image signal of the superimposed image olim (step S3).

[0028] The controller 13 outputs the separated telephoto image im1 and wide-angle image im2 to a display device such as various displays, for example (step S4).

[0029] Here, the correspondence between the telephoto image im1 and the wide-angle image im2 in steps S2 and S3 may be reversed. That is, as another example, in step S2, the wide-angle image im2 may be separated, and in step S3, the components of the wide-angle image im2 may be subtracted from the image signal of the superimposed image olim to separate the telephoto image im1.

[0030] In addition, the controller 13 can accurately separate the superimposed image olim into the telephoto image im1 and the wide-angle image im2 by using the image separation model generated by machine learning. To further improve the separation accuracy, the color components of at least one of the images may be restricted. For example, the imaging device 10 may be configured such that a first image having a first color component and a second image having a second color component different from the first color component are superimposed and imaged on the light-receiving surface 12a as a plurality of images. The first image and the second image are a plurality of images imaged on the light-receiving surface 12a and respectively correspond to the telephoto image im1 and the wide-angle image im2. Also, for example, the first color component may be a part of RGB, and the second color component may be the remaining color components not selected as the first color component.

[0031] To form an image with such restricted color components, the imaging device 10 may be configured to include a color filter in at least one of the first optical member 111 and the second optical member 112. For example, the first optical member 111 may be a dichroic coated mirror in which the reflecting surface 111a reflects or transmits only light of a specific color. Also, the first optical member 111 may be provided with an antireflection film on the back surface 111b when the reflecting surface 111a is the front surface. In the example of FIG. 2, the antireflection film is provided on the image side surface of the lens 113, and the transmittance of light of a specific color can be improved by the antireflection film.

[0032] For example, assume that a dichroic coated mirror provided on the reflecting surface 111a reflects the G component among RGB, and an antireflection film provided on the image side surface of the lens 113 transmits the R component and the B component with a high transmittance. At this time, an image corresponding to the telephoto image im1 having the G component and an image corresponding to the wide-angle image im2 having the R component and the B component are superimposed and formed on the light receiving surface 12a. As another combination, the antireflection film may transmit only one of the R component and the B component with a high transmittance, and the telephoto image im1 having the G component and the wide-angle image im2 having only one of the R component and the B component may be superimposed and formed on the light receiving surface 12a. Further, as another combination, the dichroic coated mirror may reflect the G component and the B component, and the telephoto image im1 having the G component and the B component and the wide-angle image im2 having the R component may be superimposed and formed on the light receiving surface 12a.

[0033] The controller 13 may execute separation of the telephoto image im1 or the wide-angle image im2 based on color components from the image signal of the superimposed image olim, together with the use of the image separation model or instead of the use of the image separation model. When the image separation model and the color components are used in combination, for example, the controller 13 may separate, as the telephoto image im1 or the wide-angle image im2, an image obtained by extracting only specific color components further included from candidate images of the telephoto image im1 or the wide-angle image im2 separated using the image separation model.

[0034] As described above, the imaging device 10 according to the present embodiment can obtain a telephoto image and a wide-angle image with high resolution with the above configuration.

[0035] Although the embodiments of the present disclosure have been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various deformations or modifications based on the present disclosure. Therefore, it should be noted that these deformations or modifications are included in the scope of the present disclosure. For example, the functions included in each component and the like can be rearranged so as not to be logically contradictory, and a plurality of components and the like can be combined into one or divided.

[0036] For example, in the above embodiment, the imaging optical system 11 is configured to include a Cassegrain optical system, but is not limited to such a configuration. FIG. 5 is a cross-sectional view illustrating another configuration of the imaging device 10. In FIG. 5, the same components as those in FIG. 2 are denoted by the same reference numerals. The imaging device 10 according to this modification includes the same components as those in the above embodiment, but has a region R through which the second optical member 112 passes light instead of the first optical member 111 as shown in FIG. 5. More specifically, in the imaging optical system 11 of the imaging device 10 according to this modification, at least a part of the reflecting surface 111a of the first optical member 111 faces the reflecting surface 112a of the second optical member 112, and the second optical member 112 is provided closer to the object side than the first optical member 111. The first optical member 111 is provided at a position where a part of the light that has passed through the region R of the second optical member 112 from the object side is reflected by the reflecting surface 111a of the first optical member 111 and a part of the light passes through the first optical member 111. Here, the region R may be an aperture as shown in FIG. 5, but optical elements such as lenses, transparent plates, and filters may be provided. The plurality of images formed on the light receiving surface 12a include an image formed by passing through the first optical member 111 and an image formed by being reflected by the reflecting surface 111a of the first optical member 111 and the reflecting surface 112a of the second optical member 112.

[0037] Here, f1 in FIG. 5 is the focal length of the lens 113 provided on the image side of the first optical member 111.

[0038] With the above configuration, the imaging device 10 according to this modification can obtain a telephoto image and a wide-angle image with high resolution. Here, the image processing by the controller 13 is the same as that in the above embodiment.

[0039] All of the components described in this disclosure, and / or all of the disclosed methods, or all of the steps of the processes, can be combined in any combination, except for combinations in which these features are mutually exclusive. Further, each of the features described in this disclosure can be replaced by alternative features that serve the same purpose, an equivalent purpose, or a similar purpose, unless explicitly negated. Accordingly, unless explicitly negated, each of the disclosed features is merely an example of a broader series of identical or equivalent features.

[0040] Furthermore, embodiments according to the present disclosure are not limited to any specific configurations of the above-described embodiments. Embodiments according to the present disclosure can be extended to all of the novel features described in this disclosure, or combinations thereof, or all of the novel methods, or process steps, or combinations thereof.

[0041] In this disclosure, descriptions such as "first" and "second" are identifiers for distinguishing the relevant components. The components distinguished by descriptions such as "first" and "second" in this disclosure can have their numbers exchanged within the relevant components. The exchange of identifiers is performed simultaneously. The components are still distinguishable after the exchange of identifiers. The identifiers can be deleted. The components after deletion of the identifiers are distinguished by reference signs. Based solely on the descriptions of identifiers such as "first" and "second" in this disclosure, the order of the relevant components should not be interpreted, nor should it be used as a basis for the existence of an identifier with a smaller number.

Description of Reference Signs

[0042] 10 Imaging device 11 Imaging optical system 12 Image sensor 12a Light-receiving surface 13 Controller 111 First optical member 111a Reflecting surface 111b Back surface 112 Second optical member 112a Reflecting surface 113 Lens 114 Another lens

Claims

1. An imaging optical system including a first optical member having a semi-transmissive reflecting surface and a second optical member having a reflecting surface, and an image sensor that captures an image formed through the imaging optical system. The imaging optical system is configured to include a Cassegrain optical system having the first optical member as a primary mirror and the second optical member as a secondary mirror. The first optical member has, on the image side, a lens having a region through which light from the secondary mirror to the image sensor passes. An imaging device in which a plurality of images, including an image formed through the Cassegrain optical system and an image formed through the lens without passing through the secondary mirror, are formed on the same light-receiving surface of the image sensor with different focal lengths.

2. An imaging optical system including a first optical member having a semi-transmissive reflecting surface and a second optical member having a reflecting surface, and an image sensor that captures an image formed through the imaging optical system. A plurality of images with different focal lengths are formed on the same light-receiving surface of the image sensor. The imaging optical system is configured such that at least a part of the reflecting surface of the first optical member faces the reflecting surface of the second optical member, and the second optical member is provided on the object side of the first optical member. The first optical member is provided at a position where a part of the light that has passed through the aperture of the second optical member from the object side is reflected by the reflecting surface of the first optical member, and a part of the light passes through the first optical member. The plurality of images include an image formed by passing through the first optical member and an image formed by reflection on the reflecting surface of the first optical member and the reflecting surface of the second optical member. An imaging device.

3. The imaging device according to claim 1 or 2, further comprising a controller that acquires an image signal from the image sensor and separates the plurality of images by image processing.

4. The imaging device according to claim 3, wherein the controller executes the image processing using an image separation model pre-constructed by machine learning.

5. An imaging device according to any one of claims 1 to 4, wherein a first image having a first color component and a second image having a second color component different from the first color component are superimposed and formed on the light-receiving surface as the plurality of images.

6. The imaging device according to any one of claims 1 to 5, wherein the first optical member has a dichroic coated mirror as the semi-transmissive reflecting surface, and an antireflection film is provided on the back surface when the semi-transmissive reflecting surface is the front surface.

7. The imaging device according to claim 6, wherein the curvature of the semi-transmissive reflecting surface is different from the curvature of the back surface.

8. The imaging device according to claim 1, wherein the region is an opening.

9. The imaging device according to claim 1 or 8, wherein the lens is transparent.

10. The imaging device according to claim 2, wherein the first optical member has a lens on the image side.

Images