Patent Description:
When a plurality of images are simultaneously captured, a plurality of cameras are used.

When a plurality of images are simultaneously captured by using a plurality of cameras, it is necessary to synchronize the cameras. <CIT>, <CIT>, <CIT> and <CIT> form part of the state of the art.

Hereinafter, an optical imaging apparatus <NUM> will be described with reference to the accompanying drawings. The drawings are schematic or conceptual ones.

The technical problem to be solved by the embodiments is to provide an optical imaging apparatus which can easily acquire a plurality of images at once or at the same time.

According to one example, an optical imaging apparatus includes a polarizer assembly, a polarization image sensor, and a lens assembly. The polarizer assembly is configured to acquire a first light ray of a first polarization component and a second light ray of a second polarization component which is different from the first polarization component, by using a light flux from an identical direction. The polarization image sensor is located in a position facing the polarizer assembly. The polarization image sensor is configured to acquire an image of the first polarization component and an image of the second polarization component at once or at the same time. The lens assembly includes a first lens configured to form the images on the polarization image sensor.

As illustrated in <FIG>, the optical imaging apparatus <NUM> according to the present embodiment includes a polarization image sensor (polarization camera) <NUM>, a lens assembly <NUM>, and a polarizer assembly <NUM>. In this embodiment, the polarization image sensor <NUM>, lens assembly <NUM> and polarizer assembly <NUM> have an identical optical axis C.

The polarization image sensor <NUM> is located in a position facing the polarizer assembly <NUM>. The polarization image sensor <NUM> can acquire a plurality of (two or more) different polarization components by respective pixels. For example, the polarization image sensor <NUM> can acquire image data of polarization components by using a set of polarizers of four directions of polarization axes (polarization angles) of <NUM>°, <NUM>°, <NUM>°, and <NUM>° at once or at the same time. In the present embodiment, as will be described later, the polarization image sensor <NUM> can acquire an image of a first polarization component of <NUM>°, and an image of a second polarization component of <NUM>° in each set of polarizers.

It is preferable that the polarization image sensor <NUM> includes, for example, several-million effective pixels. As an example of the polarization image sensor <NUM>, IMX250MZR manufactured by Sony Corporation is used.

The polarizer assembly <NUM> can acquire a first light ray B1 of a first polarization component and a second light ray B2 of a second polarization component that is different from the first polarization component, by using a light flux from an identical direction.

The polarizer assembly <NUM> includes a first polarizing optical element <NUM> having a circular opening edge 22a, and a second polarizing optical element <NUM> located inside the opening edge 22a of the first polarizing optical element <NUM>. Specifically, the second polarizing optical element <NUM> is disposed in the inside of the first polarizing optical element <NUM>. The center axis of the second polarizing optical element <NUM> agrees with the optical axis C. The first polarizing optical element <NUM> and second polarizing optical element <NUM> neighbor each other in a radial direction with respect to the optical axis C. The first polarizing optical element <NUM> and second polarizing optical element <NUM> have plate shapes. The thickness of each of the first polarizing optical element <NUM> and second polarizing optical element <NUM> is, for example, <NUM> or less. For example, the outer shape of the first polarizing optical element <NUM> is substantially rectangular. The outer shape of the first polarizing optical element <NUM> may be set as appropriate, such as a circular shape or the like. The outer shape of the second polarizing optical element <NUM> is discoidal. In the present embodiment, the area of the first polarizing optical element <NUM> is greater than the area of the second polarizing optical element <NUM>.

The polarizer assembly <NUM> includes the first polarizing optical element <NUM> and second polarizing optical element <NUM>, and the entirety of the polarizer assembly <NUM> may be formed in an appropriate shape, such as a cubic shape or the like.

An annular shield portion <NUM> is disposed between an outer peripheral surface 24a of the second polarizing optical element <NUM> and the opening edge 22a of the first polarizing optical element <NUM>. The shield portion <NUM> is formed of, for example, a black rubber material or the like. Thus, a boundary is formed by the shield portion <NUM> between the first polarizing optical element <NUM> and second polarizing optical element <NUM>. In the polarizer assembly <NUM>, light is prevented from passing through the shield portion <NUM>.

The first polarizing optical element <NUM> transmits, for example, linearly polarized light of a polarization axis of <NUM>°, which is included in natural light (light including components oscillating in all directions of <NUM>°) passing through the first polarizing optical element <NUM>. The second polarizing optical element <NUM> transmits, for example, linearly polarized light of a polarization axis of <NUM>°, which is included in natural light (light including components oscillating in all directions of <NUM>°) passing through the second polarizing optical element <NUM>.

In the present embodiment, the lens assembly <NUM> is located between the polarization image sensor <NUM> and polarizer assembly <NUM>. The lens assembly <NUM> includes a first lens <NUM> and a second lens <NUM>. The first lens <NUM> is opposed to the polarization image sensor <NUM>. The polarization image sensor <NUM> is located at a position of a focal distance (focal plane) f of the first lens <NUM>. The first lens <NUM> forms appropriate images on the polarization image sensor <NUM>. The second lens <NUM> is located between the first lens <NUM> and the second polarizing optical element <NUM>. The second lens <NUM> refracts the second light ray B2 of the second polarization component, which passes through the second polarizing optical element <NUM>, and makes the second light ray B2 incident on the first lens <NUM>.

The center axes of the first lens <NUM> and second lens <NUM> agree with the optical axis C. The outside diameter of the first lens <NUM> is greater than the outside diameter of the second lens <NUM>. The outside diameter of the second lens <NUM> is equal to or slightly greater than the outside diameter of the second polarizing optical element <NUM>. The outside diameter of the second lens <NUM> is less than the inside diameter of the opening edge 22a of the first polarizing optical element <NUM>.

One or more processing circuits of the optical imaging apparatus <NUM> are configured to acquire images of two or more view fields by executing a predetermined arithmetic operation on data of the first polarization component and second polarization component acquired by the polarization image sensor <NUM>. The predetermined arithmetic operation is, for example, an inverse matrix arithmetic operation in which image data of images, in which intensities of light rays from the two or more view fields are taken into account, is calculated based on the intensity data of the first polarization component and second polarization component acquired by the polarization image sensor <NUM>.

The processing circuit (controller) of the optical imaging apparatus <NUM> is, for example, an integrated circuit such as a Central Processing Unit (CPU) or Application Specific Integrated Circuit (ASIC). As the processing circuit, a general-purpose computer may be used. Aside from the case in which the processing circuit is provided as a dedicated circuit, the processing circuit may be provided as a program that is executed by a computer. In this case, the program is stored in a memory area in an integrated circuit, a memory, or the like. The processing circuit is connected to the polarization image sensor <NUM> and the memory. The processing circuit acquires acquisition data by the polarization image sensor <NUM>, executes an arithmetic operation of multiplying a proper coefficient or the like, based on this acquisition data, and calculates image data of the acquisition data.

Here, it is assumed that the intensities of the polarization components, which are acquired by the polarization image sensor <NUM> by grouping four pixels as one set, are I<NUM>, I<NUM>, I<NUM>, and I<NUM>. The processing circuit acquires, from the polarization image sensor <NUM>, the intensities I<NUM>, I<NUM>, I<NUM>, and I<NUM> of the polarization components acquired by the polarization image sensor <NUM>. Here, subscripts represent the angles of polarization.

The processing circuit can acquire the acquisition data by the polarization image sensor <NUM>. The processing circuit can generate image data, based on the acquisition data of each polarization component, which is acquired by the polarization image sensor <NUM>. The processing circuit can output to, for example, a display the image data of each polarization component, which is acquired by the polarization image sensor <NUM>, and can cause the display to display the image data.

It is assumed that intensities of light rays at object points P1, P2 (, P3) (to be described later) are S<NUM>, S<NUM>, and (S<NUM>). These satisfy the following relationship: <MAT> By performing an inverse matrix arithmetic operation, the following is obtained: <MAT> Specifically, based on signals (data I<NUM>, I<NUM>, I<NUM> indicative of intensities of respective polarization components) acquired by the polarization image sensor <NUM>, image data S<NUM>, S<NUM>, and S<NUM> of the object points P1, P2 (, P3), in which the original intensities of light rays from the object points P1, P2 (, P3) are taken into account, can be calculated. Thereby, the optical imaging apparatus <NUM> can acquire the image data S<NUM>, S<NUM>, and S<NUM> of the object points P1, P2 (, P3) in accordance with the intensities of light at the object points P1, P2 (, P3).

The above-described equation (<NUM>) is stored in the memory. The memory stores, for example, an output (image data, etc.) of the processing circuit. The memory may store an output (acquisition data) of the polarization image sensor <NUM>. Although the memory is, for example, a nonvolatile memory such as a flash memory, the memory may be a storage device such as a Hard Disk Drive (HDD), a Solid State Drive (SSD) or an integrated circuit memory device, or may further include a volatile memory.

An operation of the optical imaging apparatus <NUM> according to the present embodiment will be described.

The first polarizing optical element <NUM> illustrated in <FIG> obtains a first light ray B1 which is polarized in a direction of a first polarization axis (e.g. <NUM>°), from light rays (natural light) emanating from a first object point P1 which is located on a side opposite to the polarization image sensor <NUM>. The first light ray B1 passes through the first lens <NUM> and forms an image on the polarization image sensor <NUM>.

The second polarizing optical element <NUM> obtains a second light ray B2 which is polarized in a direction of a second polarization axis (e.g. <NUM>°), from light rays (natural light) emanating from a second object point P2 which is located on the side opposite to the polarization image sensor <NUM>. The second light ray B2 passes through the second lens <NUM> and first lens <NUM>, or, in other words, is refracted twice, and forms an image on the polarization image sensor <NUM>.

The light ray emanating from the first object point P1 and the light ray emanating from the second object point P2 are light (light flux) from the same direction (same axis) with respect to the optical imaging apparatus <NUM>.

The polarization image sensor <NUM> captures images at respective pixels by grouping polarized light rays of polarization axes of <NUM>°, <NUM>°, <NUM>° and <NUM>° as one set. Specifically, the polarization image sensor <NUM> acquires images of polarized light rays of polarization axes of <NUM>°, <NUM>°, <NUM>° and <NUM>°, by grouping four pixels as one set. The polarization image sensor <NUM> can simultaneously acquire, as independent images, an image which passes through the first polarizing optical element <NUM> of the polarization axis of <NUM>°, and an image which passes through the second polarizing optical element <NUM> of the polarization axis of <NUM>°. Actually, the polarization image sensor <NUM> can obtain four images corresponding to the polarization axes of <NUM>°, <NUM>°, <NUM>° and <NUM>°. Here, two images of the polarization axes of <NUM>° and <NUM>° are used.

The first object point P1 is located on a far-side with respect to the optical imaging apparatus <NUM>, and the second object point P2 is located on a near-side with respect to the optical imaging apparatus <NUM>. By imaging the first polarization component of <NUM>° by the polarization image sensor <NUM>, the first object point P1 can be focused and a far-side from the first object point P1 can be observed. By imaging the second polarization component of <NUM>° by the polarization image sensor <NUM>, the second object point P2, which is located on the near-side with respect to the first object point P1, can be focused and a far-side from the second object point P2 can be observed.

A first image, which is formed on the polarization image sensor <NUM> after passing through the first polarizing optical element <NUM> and first lens <NUM> from the first object point P1, is formed on the polarization image sensor <NUM> after being once refracted by the first lens <NUM>. A second image, which is formed on the polarization image sensor <NUM> after passing through the second polarizing optical element <NUM>, first lens <NUM> and second lens <NUM> from the second object point P2, is formed on the polarization image sensor <NUM> after being twice refracted by the second lens <NUM> and first lens <NUM>. Thus, the first image and second image are images with different magnifications. Accordingly, the optical imaging apparatus <NUM> can acquire, from the same position toward the same direction, images of different magnifications at the same time or at once. Specifically, the polarization image sensor <NUM> can simultaneously acquire images of two view fields of the light (light flux) from the same direction, with the viewing angles of the first image of the first object point P1 and the second image of the second object point P2 being different from each other.

In this manner, the polarization image sensor <NUM> can simultaneously acquire images of different positions on the same optical axis C. At this time, by using a single polarization image sensor <NUM>, the optical imaging apparatus <NUM> according to the present embodiment is not required to use a plurality of cameras even when a plurality of images are acquired at the same time or at once, and there is no need to perform synchronization adjustment.

According to the present embodiment, there can be provided an optical imaging apparatus <NUM> which can easily acquire a plurality of images at the same time or at once. According to this embodiment, there can be provided an optical imaging apparatus <NUM> which can acquire a plurality of images at the same time or at once by using a light flux from the same direction. According to this embodiment, there can be provided an optical imaging apparatus <NUM> which can acquire images of different positions on the same optical axis C at the same time or at once.

By using mutually different polarization degrees (<NUM>°, <NUM>°), the optical imaging apparatus <NUM> can recognize an adjacent object, for example, regardless of whether the adjacent object is a metallic body of a different kind or a metallic body of an identical kind. Thus, by using the optical imaging apparatus <NUM>, even in the case of an adjacent object of a metallic body of the identical kind and the identical color, a boundary or the like can easily be recognized. The same applies to second to seventh. embodiments which will be described later.

In the present embodiment, the example was described in which two polarizing optical elements, namely the first polarizing optical element <NUM> and second polarizing optical element <NUM>, are used as the polarizer assembly <NUM>. The polarizer assembly <NUM> may use a third polarizing optical element of, for example, <NUM>° or <NUM>°, and thereby an additional image can be obtained. In this case, for example, a polarizing optical element of <NUM>° or <NUM>° may be concentrically disposed on the outer periphery of the first polarizing optical element <NUM> and second polarizing optical element <NUM>.

Next, a purpose of use of the optical imaging apparatus <NUM> according to the first embodiment will be described with reference to <FIG>.

<FIG> illustrates a robot arm <NUM>. The robot arm <NUM> includes a robot hand <NUM> at a tip end thereof. The optical imaging apparatus <NUM> is fixed to the tip end of the arm <NUM> via, for example, a housing <NUM>.

The hand <NUM> includes a first hand element <NUM> and a second hand element <NUM>. The first hand element <NUM> includes a first link 44a which is supported on the tip end of the arm <NUM>, and a second link 44b which is supported on a tip end of the first link 44a. The first hand element <NUM> can move both the first link 44a and the second link 44b by controlling an appropriate motor, and can move one of the first link 44a and the second link 44b. The second hand element <NUM> includes a first link 46a which is supported on the tip end of the arm <NUM>, and a second link 46b which is supported on a tip end of the first link 46a. The second hand element <NUM> can move both the first link 46a and the second link 46b by controlling an appropriate motor, and can move one of the first link 46a and the second link 46b. In <FIG>, positions to which the second links 44b and 46b are moved are indicated by broken lines.

Here, a position at which the first polarization component can be imaged by the polarization image sensor <NUM> through the first polarizing optical element <NUM> and first lens <NUM>, i.e. the first object point P1 at which focusing is effected, is located on a far-side, for example, with respect to a distal end of the hand <NUM>. A position at which the second polarization component can be imaged by the polarization image sensor <NUM> through the second polarizing optical element <NUM>, second lens <NUM> and first lens <NUM>, i.e. the second object point P2 at which focusing is effected, is located on a near-side, for example, with respect to the distal end of the hand <NUM>. Thus, for example, when an object is to be grasped by the hand <NUM> of the robot arm <NUM>, the optical imaging apparatus <NUM> judges the object, based on the image of the first polarization component, until the object to be grasped approaches the hand <NUM>. In the optical imaging apparatus <NUM>, when the object to be grasped has come closer to the hand <NUM> than the appropriate distance (object point P1), the image of the first polarization component enters a blurring state. On the other hand, when the object to be grasped has come closer to the hand <NUM> than the appropriate distance (object point P1), the optical imaging apparatus <NUM> can judge the object, based on the image of the second polarization component.

Thus, when the object is to be held by the hand <NUM> of the robot arm <NUM>, the object can properly be imaged without displacing the optical axis C. Therefore, the hand <NUM> can properly be moved in relation to the object.

A second embodiment will be described with reference to <FIG>. The present embodiment is a modification of the first embodiment. The same members as those described in the first embodiment are denoted by like reference signs, and a detailed description thereof is omitted.

As illustrated in <FIG>, a first lens <NUM> according to the present embodiment is a varifocal lens. As the varifocal lens, for example, a liquid lens is used.

An upper part of <FIG> is the same as <FIG> of the first embodiment. The polarization image sensor <NUM> can acquire an image of a first object point P1a and an image of a second object point P2a.

In a lower part of <FIG>, the first lens (varifocal lens) <NUM> is adjusted, compared to the upper part of <FIG>, and the refractive index of the first lens <NUM> is increased. The first object point P1a is shifted to a third object point P1b by a distance D1 with respect to the optical imaging apparatus <NUM>, and the second object point P2a is shifted to a fourth object point P2b by a distance D2 (< D1) with respect to the optical imaging apparatus <NUM>.

In accordance with the performance of the first lens (varifocal lens) <NUM>, an image of an object point (P1b) at a proper position between the first object point P1a and second object point P2a can be formed on the polarization image sensor <NUM>. In accordance with the performance of the first lens (varifocal lens) <NUM>, an image of an object point (P2b) at a proper position between the second object point P2a and the polarizer assembly <NUM> can be formed on the polarization image sensor <NUM>.

Thus, by using the varifocal lens as the first lens <NUM>, the first lens <NUM> is properly operated, and the focal distance is varied. Thereby, compared to the example described in the first embodiment, the optical imaging apparatus <NUM> can obtain an image at a more appropriate, freely chosen position on the identical optical axis C.

By properly operating the first lens <NUM>, images of a first area (e.g. an area between the object point P1a and object point P1b in <FIG>) and a second area (e.g. an area between the object point P2a and object point P2b in <FIG>), which are different areas along the optical axis C, can be formed on the polarization image sensor <NUM> by the light rays B1 and B2 of the first polarization component and second polarization components, and the images can be captured. In this case, by varying the first lens <NUM> at a proper speed, the first area and second area can be imaged. Thus, three-dimensional imaging of an object existing in an area including the first area and second area can be quickly performed.

The polarization image sensor <NUM> can acquire, for example, an image of a position farther than the object point P1a, as an image by the first polarization component. The polarization image sensor <NUM> can acquire, for example, an image of a position farther than the object point P2a, as an image by the second polarization component. Thus, the optical imaging apparatus <NUM> according to the present embodiment can acquire, by a single polarization image sensor <NUM>, images of all areas along the optical axis C, which are farther than the object point P2b that is closest to the optical imaging apparatus <NUM>.

Note that, in connection with third to fifth embodiments to be described later, the varifocal lens denoted by reference sign <NUM> can be used as needed in place of the first lens <NUM>.

Next, a purpose of use of the optical imaging apparatus <NUM> according to the second embodiment will be described with reference to <FIG>.

<FIG> illustrates an example of an automobile <NUM> as an example of a moving body. The automobile <NUM> includes an optical imaging apparatus <NUM>, for example, at a ceiling or a windshield. The optical imaging apparatus <NUM> can observe a front side of the automobile <NUM>. The automobile <NUM> includes another optical imaging apparatus <NUM>, for example, near a rear door or a rear bumper. The optical imaging apparatus <NUM> can observe a rear side of the automobile <NUM>.

In the automobile <NUM> illustrated in <FIG>, not only the optical imaging apparatus <NUM> according to the second embodiment, but also optical imaging apparatuses <NUM> according to the first embodiment and third to seventh embodiments may be disposed as appropriate.

Next, another purpose of use of the optical imaging apparatus <NUM> according to the second embodiment will be described with reference to <FIG>.

<FIG> illustrates an example of a LiDAR apparatus <NUM>. The LiDAR apparatus <NUM> includes, for example, a power source <NUM>, a controller <NUM>, a laser beam source <NUM>, a scanning unit (scanner) <NUM>, an optical imaging apparatus <NUM>, and a measuring circuit <NUM>. The LiDAR apparatus <NUM> obtains, by the optical imaging apparatus <NUM>, reflective light RL from an object P by using a laser beam LL which is emitted from the laser beam source <NUM> in a pulse shape. Based on information acquired by the optical imaging apparatus <NUM>, the measuring circuit <NUM> measures a time from the radiation of the laser beam to the return of the reflected laser beam, calculates a distance to the object, and outputs distance information.

In the LiDAR apparatus <NUM> illustrated in <FIG>, not only the optical imaging apparatus <NUM> according to the second embodiment, but also optical imaging apparatuses <NUM> according to the first embodiment and third to seventh embodiments may be disposed as appropriate.

The LiDAR apparatus <NUM> illustrated in <FIG> may be disposed in a moving body such as the automobile <NUM>, together with the optical imaging apparatus <NUM> illustrated in <FIG>, or in place of the optical imaging apparatuses <NUM> illustrated in <FIG>.

A third embodiment will be described with reference to <FIG>. The present embodiment is a modification of the first embodiment and second embodiment. The same members as those described in the first embodiment and second embodiment are denoted by like reference signs, and a detailed description thereof is omitted.

As illustrated in <FIG>, the lens assembly <NUM> includes a third lens <NUM>, in addition to the first lens <NUM> and second lens <NUM>.

The third lens <NUM> is provided around the outer periphery of the second lens <NUM>. Specifically, the third lens <NUM> has a through-hole in a central part thereof, such that the second lens <NUM> can pass through the through-hole. Thus, the third lens <NUM> has a substantially donut-like shape. As an example of the third lens <NUM>, a Fresnel lens is used.

An inner periphery of the third lens <NUM> is fixed to the outer periphery of the second lens <NUM>. An outer periphery of the third lens <NUM> may project to the outside of the first polarizing optical element <NUM>. The third lens <NUM> changes an image formation position of the first light ray B1 with the first polarization of the first polarizing optical element <NUM> to a desired position.

A fourth embodiment will be described with reference to <FIG> and <FIG>. The present embodiment is a modification of the first to third embodiments. The same members as those described in the first to third embodiments are denoted by like reference signs, and a detailed description thereof is omitted.

As illustrated in <FIG> and <FIG>, in the present embodiment, the polarizer assembly <NUM> is located between the polarization image sensor <NUM> and lens assembly <NUM>.

In this embodiment, the lens assembly <NUM> includes one first lens <NUM>. Specifically, the lens assembly <NUM> may not include a plurality of lenses, but may include one lens. The same applies to a fifth embodiment.

The polarizer assembly <NUM> illustrated in <FIG> is located at a position of the focal distance (focal plane) f of the first lens <NUM>.

As illustrated in <FIG>, an object <NUM> is disposed in an object plane of the first lens <NUM>. It is assumed that, of the light rays emanating from an object point P of the object <NUM>, a light ray (regular reflection light) which is parallel to the optical axis C of the first lens <NUM> is a second light ray B2. It is assumed that a light ray different from the second light ray B2 is a first light ray B1. The light rays B1 and B2 reach the polarization image sensor <NUM> through the first lens <NUM> of the lens assembly <NUM> and the polarizer assembly <NUM>.

The polarizer assembly <NUM> is located at the position of the focal distance (focal plane) f of the first lens <NUM>. Thus, the second light ray B2 (regular reflection light from the object point P) which is parallel to the optical axis C is made to form an image on the second polarizing optical element <NUM> which is located at the position of the focal distance f from the first lens <NUM> and is located on the optical axis C. The second light ray B2 is imaged by the polarization image sensor <NUM> through the second polarizing optical element <NUM> of the polarizing assembly <NUM>.

On the other hand, the first light ray B1 passing through the first polarizing optical element <NUM> is scattered light. The first light ray B1 deviates from the focal position of the first lens <NUM> and passes through the first polarizing optical element <NUM> of the polarizer assembly <NUM>. The first light ray B1 is imaged by the polarization image sensor <NUM> through the first polarizing optical element <NUM> of the polarizing assembly <NUM>.

Thereby, the optical imaging apparatus <NUM> acquires a second captured image at the object point P by a telecentric optical system by the second light ray B2. The optical imaging apparatus <NUM> acquires a first captured image at the object point P by a telecentric optical system by the first light ray B1.

By using the first captured image and the second captured image, the optical imaging apparatus <NUM> can distinctly acquire the light ray B1 which emanates from the object point P in a direction that is not parallel to the optical axis C, and the light ray B2 which emanates from the object point P in a direction that is parallel to the optical axis C. Thereby, the optical imaging apparatus <NUM> can acquire information of scattering on the surface of the object <NUM>. For example, when there is a flaw or the like on the surface of the object <NUM>, regular reflection does not occur, and scattered light tends to easily occur. Thus, the acquisition of the first captured image and second captured image contributes to discovery of a flaw on the surface of the object <NUM>.

According to the present embodiment, there can be provided an optical imaging apparatus <NUM> which can easily acquire a plurality of images at the same time or at once. According to this embodiment, there can be provided an optical imaging apparatus <NUM> which can acquire a plurality of images at the same time or at once by using a light flux from the same direction.

A fifth embodiment will be described with reference to <FIG> and <FIG>. The present embodiment is a modification of the first to fourth embodiments. The same members as those described in the first to fourth embodiments are denoted by like reference signs, and a detailed description thereof is omitted.

As illustrated in <FIG> and <FIG>, in the present embodiment, the lens assembly <NUM> is located between the polarization image sensor <NUM> and polarizer assembly <NUM>.

The polarizer assembly <NUM> includes a first polarizing optical element <NUM> and a second polarizing optical element <NUM>. The first polarizing optical element <NUM> and second polarizing optical element <NUM> neighbor each other, with the optical axis C being interposed. The polarizer assembly <NUM> includes a shield portion <NUM> between the first polarizing optical element <NUM> and second polarizing optical element <NUM>. In the present embodiment, the first polarizing optical element <NUM> and second polarizing optical element <NUM> have substantially rectangular plate shapes. The shield portion <NUM> is located on the optical axis C.

As illustrated in <FIG>, a first object point Pα, a second object point Pβ, and a third object point Pγ on the optical axis C are imaged by the polarization image sensor <NUM>.

An image of the first object point Pα is formed at the position Pα0 on the polarization image sensor <NUM>. An image of the second object point Pβ is split into two positions Pβ1 and Pβ2 on the polarization image sensor <NUM>. An image of the third object point Pγ is split into two positions Pγ1 and Pγ2 on the polarization image sensor <NUM>.

A light ray Bβ from the second object point Pβ, which is farther than the first object point Pα, passes through the first polarizing optical element <NUM> and first lens <NUM>, and is then made incident on a lower-side position Pβ1 of the polarization image sensor <NUM> with respect to the optical axis C. A light ray Bβ from the second object point Pβ passes through the second polarizing optical element <NUM> and first lens <NUM>, and is then made incident on an upper-side position Pβ2 of the polarization image sensor <NUM> with respect to the optical axis C. Thus, the incidence positions with respect to the optical axis C of the light rays Bβ from the second object point Pβ, which is farther than the first object point Pα, are inverted on the polarization image sensor <NUM>.

A light ray By from the third object point Pγ, which is nearer than the first object point Pα, passes through the first polarizing optical element <NUM> and first lens <NUM>, and is then made incident on an upper-side position Pγ1 of the polarization image sensor <NUM> with respect to the optical axis C. A light ray By from the third object point Pγ passes through the second polarizing optical element <NUM> and first lens <NUM>, and is then made incident on a lower-side position Pγ2 of the polarization image sensor <NUM> with respect to the optical axis C. Thus, the incidence positions with respect to the optical axis C of the light rays By from the third object point Pγ, which is nearer than the first object point Pα, are not inverted on the polarization image sensor <NUM>.

In this manner, the second object point Pβ, which is farther than the first object point Pα whose image is formed on the polarization image sensor <NUM>, and the third object point Pγ, which is nearer than the first object point Pα, are different from each other with respect to the direction of slitting on the polarization image sensor <NUM> with respect to the optical axis C. Accordingly, the optical imaging apparatus <NUM> can judge whether a certain object point Pβ, Pγ, is nearer or farther than the first object point Pα, based on the positions Pβ1, Pβ2, Pγ1 and Pγ2 of incidence of light rays on the polarization image sensor <NUM> with respect to the optical axis C.

A distance between the first object point Pα and the second object point Pβ is calculated based on a distance between positions Pβ1 and Pβ2 of incidence (images) of the light rays Bβ from the second object point Pβ on the polarization image sensor <NUM>. A distance between the first object point Pα and the third object point Pγ is calculated based on a distance between positions Pγ1 and Pγ2 of incidence (images) of the light rays By from the third object point Pγ on the polarization image sensor <NUM>.

Thereby, the optical imaging apparatus <NUM> can calculate an actual distance from the polarization image sensor <NUM> to the object point Pβ by detecting the distance between the split images Pβ1 and Pβ2 of the object point Pβ on the polarization image sensor <NUM> and the directions of deviation of the images from the optical axis C. Similarly, the optical imaging apparatus <NUM> can calculate an actual distance from the polarization image sensor <NUM> to the object point Pγ by detecting the distance between the split images Pγ1 and Pγ2 of the object point Pγ on the polarization image sensor <NUM> and the directions of deviation of the images from the optical axis C.

The shield portion <NUM> is inserted between the first polarizing optical element <NUM> and second polarizing optical element <NUM>. Thus, the split of the object point Pβ, Pγ, becomes clearer.

A sixth embodiment will be described with reference to <FIG> and <FIG>. The present embodiment is a modification of the fifth embodiment. The same members as those described in the fifth embodiment are denoted by like reference signs, and a detailed description thereof is omitted.

As illustrated in <FIG> and <FIG>, the lens assembly <NUM> includes two first lenses 32a and 32b.

The lens 32a is located between the first polarizing optical element <NUM> and polarization image sensor <NUM>. The lens 32b is located between the second polarizing optical element <NUM> and polarization image sensor <NUM>. The lenses 32a and 32b neighbor each other, with the optical axis C being interposed.

For example, with respect to the object point P, the polarization image sensor <NUM> simultaneously acquires an image of a first polarization component (e.g. a polarization axis of <NUM>°), which passes through the first polarizing optical element <NUM> and lens 32a, and an image of a second polarization component (e.g. a polarization axis of <NUM>°), which passes through the second polarizing optical element <NUM> and lens 32b. The two images are acquired by one polarization image sensor <NUM>. This is the same as the case in which one image is an image of a left camera and the other image is an image of a right camera. Thus, the optical imaging apparatus <NUM> according to the present embodiment can be constituted as a stereo camera by using the two lenses 32a and 32b. A distance between the two lenses 32a and 32b is known. Accordingly, the optical imaging apparatus <NUM> can measure, for example, a distance D between the polarizer assembly <NUM> and the object point P.

As regards the sixth embodiment, the varifocal lens denoted by reference sign <NUM> can be used in place of the lens 32a, 32b, as needed.

A seventh embodiment will be described with reference to <FIG>. The present embodiment is a modification of the first to sixth embodiments. The same members as those described in the first to sixth embodiments are denoted by like reference signs, and a detailed description thereof is omitted.

As illustrated in <FIG>, an optical imaging apparatus <NUM> according to the present embodiment includes a polarization image sensor (polarization camera) <NUM>, a lens assembly <NUM>, a polarizer assembly <NUM>, a light source <NUM>, and mirrors <NUM> and <NUM>.

The polarizer assembly <NUM> is disposed on a front side (light emission side) of the light source <NUM>. The polarizer assembly <NUM> includes a polarization beam splitter <NUM>. The polarization beam splitter <NUM> acquires a first light ray B1 of a first polarization component and a second light ray B2 of a second polarization component from light from the light source <NUM>, the light being used as a light flux from an identical direction.

The polarization beam splitter <NUM> is inclined to the optical axis C1 of the light source <NUM> by, for example, <NUM>°. The polarization beam splitter <NUM> of the polarizer assembly <NUM> is located between a first lens <NUM> and a second lens <NUM> (to be described later) of the lens assembly <NUM>. An optical axis C2 of the first lens <NUM> and second lens <NUM> of the lens assembly <NUM> is perpendicular to the optical axis C1 of the light source <NUM>.

The lens assembly <NUM> includes a first lens (image formation lens) <NUM>, a second lens (image formation lens) <NUM>, and a third lens (image formation lens) <NUM>. As regards the seventh embodiment, the varifocal lens denoted by reference sign <NUM> can be used in place of the lens <NUM>, <NUM>, <NUM>, as needed.

The first lens <NUM> is located between the polarization beam splitter <NUM> and an observation target object P. A first surface Sa of the object P of the observation target exists on an optical path of light passing through the first lens <NUM>. The first lens <NUM> is located at a distance of a focal distance f1 from the first surface Sa of the object P of the observation target.

The second lens <NUM> is located between the polarization beam splitter <NUM> and the polarization image sensor <NUM>. The second lens <NUM> is located at a distance of a focal distance f2 from the polarization image sensor <NUM>.

The mirror <NUM> is located on the optical axis C1 of the light source <NUM>. The polarization beam splitter <NUM> is located between the mirror <NUM> and the light source <NUM>. The mirror <NUM> reflects the light passing through the polarization beam splitter <NUM> in a direction of <NUM>°. The third lens <NUM> and mirror <NUM> are located on an optical path of light reflected by the mirror <NUM>. The mirror <NUM> reflects the light passing through the third lens <NUM> in a direction of <NUM>°. A second surface Sb of the object P exists on an optical path of light reflected by the mirror <NUM>. The third lens <NUM> is located at a distance (optical path length) of a focal distance f3 from the second surface Sb of the object P of the observation target.

The light source <NUM> includes a light-emitting element <NUM>, a first lens <NUM> and a second lens <NUM>. For example, an LED is used as the light-emitting element <NUM>. The first lens <NUM> converts light emitted from the light-emitting element <NUM> to a parallel beam. A shield portion <NUM> is provided on a center axis of the second lens <NUM>. The shield portion <NUM> has a discoidal shape. Thus, the second <NUM> convers the light from the light-emitting element <NUM> to light of a substantially donut-like shape. Note that the light from the light-emitting element <NUM> includes light oscillating in all directions (directions of <NUM>°).

The light from the light-emitting element <NUM> of the light source <NUM> is converted to a parallel beam by the first lens <NUM>, and the parallel beam is incident on the second lens <NUM>. By the shield portion <NUM> of the second lens <NUM>, the light from the light-emitting element <NUM> is incident on the polarization beam splitter <NUM> as the light of the donut-like shape. The polarization beam splitter <NUM> reflects S polarized light (first light ray B1) and transmits P polarized light (second light ray B2).

Of the light from the light source <NUM>, the S polarized light reflected by the polarization beam splitter <NUM> is incident on the first surface Sa of the object P through the first lens <NUM>. At this time, since the light from the light source <NUM> is made to have a donut-like shape by the shield portion <NUM> of the second lens <NUM>, the S polarized light that is incident on the first surface Sa is made obliquely incident. The light that is made obliquely incident on the first surface Sa of the object P is scattered, and the polarization rotates. Of the light that is made obliquely incident on the first surface Sa, the polarization of a regular reflection component does not rotate. Thus, the light reflected from the first surface Sa of the object P includes S polarized light and P polarized light. The reflective light including the S polarized light and P polarized light is made incident on the polarization beam splitter <NUM> through the first lens <NUM>. Of the light including the S polarized light and P polarized light, the polarization beam splitter <NUM> reflects the S polarized light and transmits the P polarized light. Thus, of the reflected light from the first surface Sa of the object P, the polarization beam splitter <NUM> reflects the S polarized light toward the light source <NUM> and transmits the P polarized light. The P polarization component that passes through the polarization beam splitter <NUM> is made incident on the polarization image sensor <NUM> through the second lens <NUM>.

Of the light from the light source <NUM>, the P polarized light that passes through the polarization beam splitter <NUM> is incident on the second surface Sb of the object P via the mirror <NUM>, third lens <NUM> and mirror <NUM>. At this time, since the light from the light source <NUM> is made to have a donut-like shape by the shield portion <NUM> of the second lens <NUM>, the P polarized light that is incident on the second surface Sb is made obliquely incident. The light that is made obliquely incident on the second surface Sb of the object P is scattered, and the polarization rotates. Of the light that is made obliquely incident on the second surface Sb, the polarization of a regular reflection component does not rotate. Thus, the light reflected from the second surface Sb of the object P includes P polarized light and S polarized light. The reflective light including the P polarized light and S polarized light is made incident on the polarization beam splitter <NUM> via the mirror <NUM>, third lens <NUM> and mirror <NUM>. Of the light including the P polarized light and S polarized light, the polarization beam splitter <NUM> transmits the P polarized light and reflects the S polarized light. Thus, of the reflective light from the second surface Sb of the object P, the polarization beam splitter <NUM> transmits the P polarized light toward the light source <NUM> and reflects the S polarized light. The S polarization component reflected by the polarization beam splitter <NUM> is made incident on the polarization image sensor <NUM> through the second lens <NUM>.

Accordingly, the light from the first surface Sa of the object P is made incident on the polarization image sensor <NUM> as the P polarization component. The light from the second surface Sb of the object P is made incident on the polarization image sensor <NUM> as the S polarization component. Thus, the optical imaging apparatus <NUM> acquires, by the polarization image sensor <NUM>, two images of the P polarization component from the first surface Sa of the object P and the S polarization component from the second surface Sb of the object P. In this manner, by the polarization image sensor <NUM>, the optical imaging apparatus <NUM> acquires images from two view points at the same time or at once. By utilizing this, the optical imaging apparatus <NUM> can acquire only scattered light.

Claim 1:
An optical imaging apparatus (<NUM>) comprising:
a polarizer assembly (<NUM>) configured to acquire a first light ray of a first polarization component and a second light ray of a second polarization component which is different from the first polarization component, by using a light flux from an identical direction;
a polarization image sensor (<NUM>) located in a position facing the polarizer assembly, and configured to acquire an image of the first polarization component and an image of the second polarization component at once or at the same time; and
a lens assembly (<NUM>) including a first lens (<NUM>) configured to form the images on the polarization image sensor, wherein
the polarizer assembly includes:
a first polarizing optical element (<NUM>) configured to acquire the first light ray of the first polarization component; and
a second polarizing optical element (<NUM>) configured to acquire the second light ray of the second polarization component, and
the first polarizing optical element and the second polarizing optical element neighbor each other, and
wherein
the second polarizing optical element is disposed inside the first polarizing optical element,
the first polarizing optical element and the second polarizing optical element are concentric, characterized in that
the polarizer assembly is located between the first lens and the polarization image sensor and is located in a focal plane of the first lens.