Imaging device

Abstract

An imaging device (10) includes: a light splitting element (18) including a first splitting surface (30) that splits incident light (50) into first reflected light (52) and first transmitted light (54), and a second splitting surface (36) that splits the first transmitted light (54) into second reflected light (56) and second transmitted light (58); a first sensor (12) for capturing an image of the first reflected light (52); a second sensor (14) for capturing a second reflected light (56); and a third sensor (16) for capturing an image of the second transmitted light (58). One of the first sensor (12), the second sensor (14) and the third sensor (16) is a polarization sensor, the other is a visible light sensor, and the other is an infrared light sensor.

Description

Technical Field

[0001] The invention relates to a photographing device. Background Art

[0002] As a multi-plate imaging device that uses a plurality of sensors to capture common incident light, there is a known structure that uses a multi-plate prism. For example, there is a known structure that provides a polarizing plate on each of a plurality of sensors to detect the polarization component of the incident light, and a structure that uses a dichroic prism to capture red, green, blue, and infrared light separately (for example, see Patent Documents 1 and 2).

[0003] Prior Art Literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 9-281441

[0006] Patent document 2: Japanese Patent Application Publication No. 2019-86536. Summary of the invention

[0007] In certain applications, it is preferable to be able to capture all of visible light images, infrared light images, and polarization images.

[0008] The present invention has been made in view of the above situation, and an object thereof is to provide a photographing device capable of photographing visible light images, infrared light images, and polarization images.

[0009] A shooting device according to a certain embodiment of the present invention includes: a light splitting element, including a first splitting surface for splitting incident light into a first reflected light and a first transmitted light, and a second splitting surface for splitting the first transmitted light into a second reflected light and a second transmitted light; a first sensor for shooting the first reflected light; a second sensor for shooting the second reflected light; and a third sensor for shooting the second transmitted light. One of the first sensor, the second sensor and the third sensor is a polarization sensor, which includes: a plurality of first pixels, provided with a first polarizer that allows linear polarized light in a first direction to pass through; a plurality of second pixels, provided with a second polarizer that allows linear polarized light in a second direction to pass through, the second direction intersects with the first direction; a plurality of third pixels, provided with a third polarizer that allows linear polarized light in a third direction to pass through, the third direction intersects with the first direction and the second direction; a plurality of fourth pixels, provided with a fourth polarizer that allows linear polarized light in a fourth direction to pass through, the fourth direction intersects with the first direction, the second direction and the third direction, another one of the first sensor, the second sensor and the third sensor is a visible light sensor, the visible light sensor includes a plurality of pixels provided with a filter that allows visible light to pass through, and another one of the first sensor, the second sensor and the third sensor is an infrared light sensor, the infrared light sensor includes a plurality of pixels provided with a filter that allows infrared light to pass through.

[0010] Furthermore, any combination of the above-described constituent elements and any substitutions between constituent elements and methods, apparatuses, systems, and the like of the present invention may also be practiced as additional modes of the present invention.

[0011] According to the present invention, it is possible to provide a photographing device capable of photographing visible light images, infrared light images, and polarization images. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a diagram schematically showing the configuration of the imaging device according to the first embodiment.

[0013] Figure 2 It is a diagram schematically showing the structure of a polarizing plate included in the polarization sensor.

[0014] Figure 3 It is a diagram schematically showing the structure of a visible light filter included in the visible light sensor.

[0015] Figure 4 It is a diagram schematically showing the configuration of an imaging device according to the second embodiment.

[0016] Figure 5 It is a diagram schematically showing the configuration of an imaging device according to the second embodiment. DETAILED DESCRIPTION

[0017] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The specific numerical values ​​shown in the embodiments are merely examples for facilitating understanding of the invention and do not constitute limitations of the present invention unless otherwise specified. In addition, in the accompanying drawings, illustrations of elements that are not directly related to the present invention are omitted.

[0018] The present embodiment is briefly described. The present embodiment is a photographing device that uses a light splitting element to split common incident light into a plurality of lights, and uses a polarization sensor, a visible light sensor, and an infrared light sensor to respectively photograph the plurality of split lights. The photographing device involved in the present embodiment can be used, for example, as a vehicle-mounted sensor for detecting objects around a vehicle. In the present embodiment, by suppressing the change in the polarization state of the incident light on the optical path before reaching the polarization sensor, the polarization sensor can capture a suitable polarization image.

[0019] (First Embodiment)

[0020] Figure 11 is a diagram schematically showing the structure of an imaging device 10 according to the first embodiment. The imaging device 10 includes a first sensor 12, a second sensor 14, a third sensor 16, a light splitting element 18, and a phase difference plate 20. The imaging device 10 is a so-called three-plate camera, which is configured to split incident light 50 using the light splitting element 18, and to capture images using the first sensor 12, the second sensor 14, and the third sensor 16, respectively.

[0021] The light dividing element 18 includes a first prism 22, a second prism 24, and a third prism 26. The light dividing element 18 is a so-called three-plate prism. The first prism 22 includes a first incident surface 28, a first split surface 30, and a first exit surface 32. The second prism 24 includes a second incident surface 34, a second split surface 36, and a second exit surface 38. The third prism 26 includes a third incident surface 40 and a third exit surface 42. An air gap is provided between the first split surface 30 and the second incident surface 34.

[0022] The incident light 50 incident on the first incident surface 28 is split into a first reflected light 52 and a first transmitted light 54 at the first dividing surface 30. The first reflected light 52 reflected at the first dividing surface 30 undergoes total internal reflection at the first incident surface 28, then passes through the first emission surface 32 and is emitted toward the first sensor 12. The first transmitted light 54 transmitted through the first dividing surface 30 is split into a second reflected light 56 ​​and a second transmitted light 58 at the second dividing surface 36. The second reflected light 56 ​​reflected at the second dividing surface 36 undergoes total internal reflection at the second incident surface 34, then passes through the second emission surface 38 and is emitted toward the second sensor 14. The second transmitted light 58 transmitted through the second dividing surface 36 passes through the third incident surface 40 and the third emission surface 42 and is emitted toward the third sensor 16.

[0023] The first sensor 12, the second sensor 14, and the third sensor 16 are polarization sensors, visible light sensors, or infrared light sensors. Specifically, one of the first sensor 12, the second sensor 14, and the third sensor 16 is a polarization sensor, another of the first sensor 12, the second sensor 14, and the third sensor 16 is a visible light sensor, and another of the first sensor 12, the second sensor 14, and the third sensor 16 is an infrared light sensor. The polarization sensor, the visible light sensor, and the infrared light sensor each include a photographing element having a plurality of pixels. As a photographing element, a two-dimensional image sensor such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) can be used.

[0024] Figure 2: is a diagram schematically showing the structure of polarizers 60a, 60b, 60c, and 60d included in the polarization sensor 60. The polarization sensor 60 includes a first polarizer 60a, a second polarizer 60b, a third polarizer 60c, and a fourth polarizer 60d, which are arranged corresponding to each pixel of the imaging element. The first polarizer 60a selectively transmits linear polarized light in a first direction (for example, a 0-degree direction). The second polarizer 60b selectively transmits linear polarized light in a second direction (for example, a 90-degree direction) intersecting the first direction. The third polarizer 60c selectively transmits linear polarized light in a third direction (for example, a 45-degree direction) intersecting the first direction and the second direction. The fourth polarizer 60d selectively transmits linear polarized light in a fourth direction (for example, a 135-degree direction) intersecting the first direction, the second direction, and the third direction. Each polarizer 60a to 60d is arranged in a Bayer array in a manner corresponding to a plurality of pixels of the imaging element. The polarization sensor 60 includes a plurality of first pixels provided with a first polarizing plate 60 a , a plurality of second pixels provided with a second polarizing plate 60 b , a plurality of third pixels provided with a third polarizing plate 60 c , and a plurality of fourth pixels provided with a fourth polarizing plate 60 d .

[0025] Figure 3 : is a diagram schematically showing the structure of visible light filters 62R, 62G, and 62B included in the visible light sensor 62. The visible light sensor 62 includes a red filter 62R, a green filter 62G, and a blue filter 62B arranged corresponding to each pixel of the imaging element. Each visible light filter 62R, 62G, and 62B is arranged in a Bayer array in a manner corresponding to a plurality of pixels of the imaging element. The visible light sensor 62 includes a plurality of pixels provided with a red filter 62R, a plurality of pixels provided with a green filter 62G, and a plurality of pixels provided with a blue filter 62B.

[0026] The infrared light sensor (not shown) includes a plurality of pixels provided with an infrared light filter, and the infrared light filter selectively transmits infrared light. The infrared light sensor is, for example, a distance image sensor that measures the distance to an object by using infrared light irradiated toward the object from an infrared light source provided separately from the camera 10, such as a LIDAR (Light Detection And Ranging) sensor. The infrared light sensor measures the distance to an object by, for example, a ToF (Time of Flight) method.

[0027] exist Figure 1In the first embodiment, the first sensor 12 may be a polarization sensor 60. The first reflected light 52 directed to the first sensor 12 is reflected at the first split surface 30 and the first incident surface 28, thereby causing the polarization state of the first reflected light 52 to change. That is, the polarization state of the first reflected light 52 may change according to the polarization state of the incident light 50. In particular, when the first reflected light 52 is totally internally reflected at the first incident surface 28, which is the interface between the prism and the air, the polarization state of the first reflected light 52 may change significantly. If the polarization state of the first reflected light 52 changes according to the polarization state of the incident light 50, the polarization sensor 60 may not accurately measure the polarization state of the incident light 50.

[0028] In the present embodiment, in order to compensate for the change in the polarization state of the first reflected light 52 caused by the light dividing element 18, a phase difference plate 20 is provided between the first sensor 12 and the light dividing element 18. The phase difference of the phase difference plate 20 is set to reduce or cancel the phase difference between the s-polarization component and the p-polarization component of the first reflected light 52 generated by at least one of the reflection at the first dividing surface 30 and the reflection at the first incident surface 28. The magnitude of the phase difference provided by the phase difference plate 20 is not particularly limited, and is, for example, approximately 120 degrees.

[0029] When the first sensor 12 is a polarization sensor 60, the first dividing surface 30 preferably includes a non-polarizing beam splitter that is not wavelength-dependent. "Non-polarizing" here means that the effect on polarization is so small that it can be ignored. The non-polarizing beam splitter is configured to make the change in polarization state before and after reflection and before and after transmission of the beam splitter so small that it can be ignored. As a non-polarizing beam splitter that is not wavelength-dependent, for example, a metal film can be used. As a non-polarizing beam splitter that is not wavelength-dependent, a dielectric multilayer film designed to suppress changes in polarization state can also be used. By providing a non-polarizing beam splitter at the first dividing surface 30, changes in the polarization state of the first reflected light 52 reflected at the first dividing surface 30 can be suppressed.

[0030] When the first sensor 12 is a polarization sensor 60, one of the second sensor 14 and the third sensor 16 is a visible light sensor 62, and the other of the second sensor 14 and the third sensor 16 is an infrared light sensor. In this case, the second split surface 36 preferably includes a dichroic mirror that separates visible light and infrared light. As the dichroic mirror, for example, a dielectric multilayer film can be used. When the second sensor 14 is a visible light sensor 62, the dichroic mirror arranged at the second split surface 36 is designed to selectively reflect visible light and selectively transmit infrared light. When the second sensor 14 is an infrared light sensor, the dichroic mirror arranged at the second split surface 36 is designed to selectively transmit visible light and selectively reflect infrared light. In addition, the second split surface 36 may not include a dichroic mirror, but may include a beam splitter that is not wavelength-dependent, such as a half-reflecting mirror.

[0031] According to the present embodiment, by using the light splitting element 18, the incident light 50 can be photographed using the polarization sensor 60, the visible light sensor 62, and the infrared light sensor, respectively, thereby obtaining a polarization image, a visible light image, and an infrared light image. According to the present embodiment, by setting the first sensor 12 as the polarization sensor 60, a structure in which a dichroic mirror is not arranged on the optical path toward the polarization sensor 60 can be realized. Thus, a polarization image that is not affected by the change in the polarization state of the dichroic mirror can be obtained. In addition, by providing a phase difference plate 20 between the light splitting element 18 and the polarization sensor 60 (first sensor 12), the change in the polarization state of the first reflected light 52 generated on at least one of the first splitting surface 30 and the first incident surface 28 can be suppressed. Thus, a polarization image in which the change in the polarization state of the incident light 50 is suppressed can be obtained.

[0032] (Second Embodiment)

[0033] Figure 4 1 is a diagram schematically showing the structure of an imaging device 10A according to a second embodiment. The second embodiment differs from the first embodiment in that a phase difference plate 20A is provided between the second sensor 14 and the light dividing element 18. The second embodiment will be described below with the differences from the first embodiment as the center, and the description of the same points will be appropriately omitted.

[0034] The imaging device 10A includes a first sensor 12, a second sensor 14, a third sensor 16, a light dividing element 18, and a phase difference plate 20A. In the second embodiment, the second sensor 14 is a polarization sensor 60. In the second embodiment, one of the first sensor 12 and the third sensor 16 is a visible light sensor 62, and the other of the first sensor 12 and the third sensor 16 is an infrared light sensor.

[0035] When the first sensor 12 is a visible light sensor 62 and the third sensor 16 is an infrared light sensor, the first dividing surface 30 preferably includes a non-polarizing beam splitter that is not wavelength-dependent. By providing a non-polarizing beam splitter at the first dividing surface 30, changes in the polarization state of the first transmitted light 54 that passes through the first dividing surface 30 can be suppressed. When the first sensor 12 is a visible light sensor 62 and the third sensor 16 is an infrared light sensor, the second dividing surface 36 is preferably a non-polarizing dichroic mirror. The dichroic mirror provided at the second dividing surface 36 is designed to selectively reflect visible light and selectively transmit infrared light. By providing a non-polarizing dichroic mirror at the second dividing surface 36, changes in the polarization state of the second reflected light 56 ​​reflected at the second dividing surface 36 can be suppressed. In addition, the second dividing surface 36 may not include a dichroic mirror, but may include a non-polarizing beam splitter that is not wavelength-dependent, such as a half-reflecting mirror.

[0036] When the first sensor 12 is an infrared light sensor and the third sensor 16 is a visible light sensor 62, the first dividing surface 30 is preferably a non-polarizing dichroic mirror. As a non-polarizing dichroic mirror, for example, a dielectric multilayer film designed to suppress the change of polarization state from the visible light region to the infrared light region can be used. The dichroic mirror arranged at the first dividing surface 30 is designed to selectively transmit visible light and selectively reflect infrared light. By arranging a non-polarizing dichroic mirror at the first dividing surface 30, the change of the polarization state of the first transmitted light 54 passing through the first dividing surface 30 can be suppressed. In addition, the first dividing surface 30 may not include a dichroic mirror, but include a non-polarizing beam splitter that is not wavelength-dependent. When the first sensor 12 is an infrared light sensor and the third sensor 16 is a visible light sensor 62, the second dividing surface 36 preferably includes a non-polarizing beam splitter that is not wavelength-dependent. By arranging a non-polarizing beam splitter at the second dividing surface 36, the change of the polarization state of the second reflected light 56 ​​reflected at the second dividing surface 36 can be suppressed.

[0037] The phase difference of the phase difference plate 20A is set to reduce or offset the phase difference between the s-polarization component and the p-polarization component of the second reflected light 56 ​​generated by at least one of the transmission of the first split surface 30, the reflection at the second split surface 36, and the reflection at the second incident surface 34. The phase difference plate 20A compensates for the change in the polarization state of the second reflected light 56 ​​caused by the light splitting element 18. In particular, when the second reflected light 56 ​​is totally internally reflected at the second incident surface 34 as the interface between the prism and the air, the polarization state of the second reflected light 56 ​​may change significantly. The magnitude of the phase difference provided by the phase difference plate 20A is not particularly limited, for example, it is about 120 degrees.

[0038] In the present embodiment, it is also possible to obtain a polarization image, a visible light image, and an infrared light image by using the light dividing element 18, thereby using the polarization sensor 60, the visible light sensor 62, and the infrared light sensor to respectively capture the incident light 50. According to the present embodiment, by providing a phase difference plate 20A between the light dividing element 18 and the polarization sensor 60 (the second sensor 14), the change in the polarization state of the second reflected light 56 ​​generated on at least one of the first dividing surface 30, the second dividing surface 36, and the second incident surface 34 can be suppressed. According to the present embodiment, by providing a non-polarizing dichroic mirror at the first dividing surface 30 or the second dividing surface 36, a polarization image in which the change in the polarization state at the dichroic mirror is suppressed can be obtained. According to the present embodiment, by providing a non-polarizing beam splitter at the first dividing surface 30 or the second dividing surface 36, a polarization image in which the change in the polarization state at the beam splitter is suppressed can be obtained.

[0039] (Third Embodiment)

[0040] Figure 5 1 is a diagram schematically showing the structure of the imaging device 10B involved in the third embodiment. The third embodiment is different from the first embodiment and the second embodiment in that the phase difference plate 20, 20A is not provided. The third embodiment will be described below with the differences from the first embodiment and the second embodiment as the center, and the description of the same points will be appropriately omitted.

[0041] The imaging device 10B includes a first sensor 12, a second sensor 14, a third sensor 16, and a light dividing element 18. In the third embodiment, the third sensor 16 is a polarization sensor 60. In the third embodiment, one of the first sensor 12 and the second sensor 14 is a visible light sensor 62, and the other of the first sensor 12 and the second sensor 14 is an infrared light sensor.

[0042] When the first sensor 12 is a visible light sensor 62 and the second sensor 14 is an infrared light sensor, the first dividing surface 30 preferably includes a non-polarizing beam splitter that is not wavelength-dependent. By providing a non-polarizing beam splitter at the first dividing surface 30, changes in the polarization state of the first transmitted light 54 passing through the first dividing surface 30 can be suppressed. When the first sensor 12 is a visible light sensor 62 and the second sensor 14 is an infrared light sensor, the second dividing surface 36 is preferably a non-polarizing dichroic mirror. The dichroic mirror provided on the second dividing surface 36 is designed to selectively transmit visible light and selectively reflect infrared light. By providing a non-polarizing dichroic mirror on the second dividing surface 36, changes in the polarization state of the second transmitted light 58 passing through the second dividing surface 36 can be suppressed. In addition, the second dividing surface 36 may also include a non-polarizing beam splitter that is not wavelength-dependent, such as a half-reflecting mirror, instead of a dichroic mirror.

[0043] When the first sensor 12 is an infrared light sensor and the second sensor 14 is a visible light sensor 62, the first dividing surface 30 is preferably a non-polarizing dichroic mirror. The dichroic mirror arranged on the first dividing surface 30 is designed to selectively transmit visible light and selectively reflect infrared light. By arranging a non-polarizing dichroic mirror on the first dividing surface 30, the change in the polarization state of the first transmitted light 54 passing through the first dividing surface 30 can be suppressed. In addition, the first dividing surface 30 may also not include a dichroic mirror, but include a non-polarizing beam splitter that is not wavelength-dependent. When the first sensor 12 is an infrared light sensor and the second sensor 14 is a visible light sensor 62, the second dividing surface 36 preferably includes a non-polarizing beam splitter that is not wavelength-dependent. By arranging a non-polarizing beam splitter on the second dividing surface 36, the change in the polarization state of the second transmitted light 58 passing through the second dividing surface 36 can be suppressed.

[0044] In the present embodiment, by also using the light dividing element 18, the incident light 50 can be photographed by using the polarization sensor 60, the visible light sensor 62 and the infrared light sensor, respectively, so as to obtain a polarization image, a visible light image and an infrared light image. According to the present embodiment, by setting the third sensor 16 as the polarization sensor 60, a structure in which total internal reflection does not occur on the optical path toward the polarization sensor 60 can be realized. Thus, a polarization image that is not affected by the change in polarization state caused by total internal reflection can be obtained. According to the present embodiment, by setting a non-polarizing dichroic mirror or a beam splitter on the first dividing surface 30 and the second dividing surface 36, the change in the polarization state of the second transmitted light 58 caused by the transmission of the first dividing surface 30 and the second dividing surface 36 can be suppressed. In this way, even if a phase difference plate is not set between the light dividing element 18 and the polarization sensor 60 (third sensor 16), a suitable polarization image can be obtained.

[0045] As mentioned above, the present invention has been described with reference to the above-mentioned embodiments, but the present invention is not limited to the above-mentioned embodiments, and appropriate combinations or substitutions of the structures shown in the examples are also included in the scope of the present invention.

[0046] Industrial Applicability

[0047] According to the present invention, it is possible to provide a photographing device capable of photographing visible light images, infrared light images, and polarization images.

[0048] Explanation of symbols

[0049] 10…Photography equipment

[0050] 12…First sensor

[0051] 14…Second sensor

[0052] 16…Third sensor

[0053] 18…Light dividing element

[0054] 20…Phase difference plate

[0055] 22…First Prism

[0056] 24…Second prism

[0057] 26…The Third Prism

[0058] 28…First incident surface

[0059] 30…First dividing surface

[0060] 32…First ejection surface

[0061] 34…Second incident surface

[0062] 36…Second dividing surface

[0063] 38…Second emission surface

[0064] 40…Third incident surface

[0065] 42…third emission surface

[0066] 50…Incident light

[0067] 52…First reflected light

[0068] 54…First transmitted light

[0069] 56…Second reflected light

[0070] 58…Second transmitted light

[0071] 60…Polarization sensor

[0072] 60a…first polarizer

[0073] 60b…Second polarizer

[0074] 60c…Third polarizer

[0075] 60d…Fourth polarizer

[0076] 62…Visible light sensor

[0077] 62R…Red filter

[0078] 62G…Green filter

[0079] 62B…Blue filter.

Claims

1. A photographing device, include: A light splitting element including a first splitting surface for splitting incident light into a first reflected light and a first transmitted light and a second splitting surface for splitting the first transmitted light into a second reflected light and a second transmitted light; A first sensor, used for photographing the first reflected light; a second sensor, used for photographing the second reflected light; as well as a third sensor, for photographing the second transmitted light, One of the first sensor, the second sensor and the third sensor is a polarization sensor, and the polarization sensor includes: a plurality of first pixels provided with a first polarizer that transmits linear polarized light in a first direction; A plurality of second pixels are provided with a second polarizer that transmits linear polarized light in a second direction, the second direction intersects with the first direction; a plurality of third pixels are provided with a third polarizer that transmits linear polarized light in a third direction, the third direction intersects with the first direction and the second direction; a plurality of fourth pixels are provided with a fourth polarizer that transmits linear polarized light in a fourth direction, the fourth direction intersects with the first direction, the second direction and the third direction, Another one of the first sensor, the second sensor, and the third sensor is a visible light sensor including a plurality of pixels provided with a filter that transmits visible light. Another one of the first sensor, the second sensor and the third sensor is an infrared light sensor including a plurality of pixels provided with a filter that transmits infrared light.

2. The photographing device according to claim 1, in, One of the first splitting surface and the second splitting surface includes a non-polarizing dichroic mirror that separates visible light and infrared light, The other of the first splitting surface and the second splitting surface includes a non-polarizing beam splitter.

3. The photographing device according to claim 1 or 2, further comprising: include: A phase difference plate is provided between the light dividing element and the polarization sensor.

4. The photographing device according to claim 1 or 2, in, The light dividing element includes: a first prism including the first dividing surface; and a second prism including the second dividing surface, The first prism further includes: a first incident surface, from which the incident light is incident; and a first exit surface, from which the first reflected light is emitted after total internal reflection at the first incident surface. The second prism further includes: a second incident surface, through which the first transmitted light from the first split surface is incident; and a second exit surface, through which the second reflected light is emitted after total internal reflection at the second incident surface. The polarization sensor is the first sensor, The photographing device further includes a phase difference plate disposed between the first emission surface and the polarization sensor.

5. The photographing device according to claim 1 or 2, in, The light dividing element includes: a first prism including the first dividing surface; and a second prism including the second dividing surface, The first prism further includes: a first incident surface, from which the incident light is incident; and a first exit surface, from which the first reflected light is emitted after total internal reflection at the first incident surface. The second prism further includes: a second incident surface, through which the first transmitted light from the first split surface is incident; and a second exit surface, through which the second reflected light is emitted after total internal reflection at the second incident surface. The polarization sensor is the third sensor.

Images