JP2021144138A - Imaging device - Google Patents

Abstract

To reduce illumination light as unnecessary light incident on an imaging element when performing illumination and imaging of a subject through a common optical system.SOLUTION: An imaging device 4 includes: an imaging element 11 for picking up imaging light incident on an imaging optical system 9 from a subject; light source systems 6 and 7 for emitting first polarized light serving as illumination light irradiated to the subject through the imaging optical system; and a polarization separation element 8 that directs the illumination light to the imaging optical system and directs the imaging light from the imaging optical system to the imaging element by reflecting one of the first polarized light and second polarized light serving as imaging light of which polarization direction is different from that of the polarized light and transmitting the other; and a polarization element 10 that is arranged between the polarization separation element and the imaging element and blocks the first polarized light by transmitting the second polarized light.SELECTED DRAWING: Figure 2

Description

The present invention relates to an imaging device that illuminates a subject and captures images through a common optical system.

By performing the illumination and imaging of the subject through a common optical system (imaging optical system), it is possible to reduce the deviation from the illumination region with respect to the imaging region on the subject side.

As an imaging device that emits light to the outside through an imaging optical system that guides light from the outside to an imaging element, there are those disclosed in Patent Document 1 and Patent Document 2. The imaging devices of Patent Documents 1 and 2 have a projector function of displaying a subject image recorded by imaging through an imaging optical system on a display element and projecting image light from the display element onto a screen through the same imaging optical system. .. An optical path separation element for separating an optical path is provided between the image pickup optical system and the image pickup element and the display element.

Japanese Unexamined Patent Publication No. 2004-040817 Japanese Unexamined Patent Publication No. 2012-222695

However, in the image pickup apparatus of Patent Document 1, a polarizing element is not arranged between the image pickup element and the optical path separation element. Therefore, when the subject is illuminated and imaged at the same time by using the configuration of this image pickup device, unnecessary light that does not go from the optical path separation element to the image pickup optical system among the illumination light due to the characteristics of the optical path separation element becomes the image pickup element. There is a risk of incident. Further, in the image pickup apparatus of Patent Document 2, a light-shielding member that blocks image light from the display element is provided between the image pickup element and the optical path separation element, and the subject is illuminated and imaged by using the configuration including the light-shielding member. Even if the above is performed at the same time, not only the illumination light but also the image pickup light from the subject is blocked by the light-shielding member and the image pickup cannot be performed.

The present invention provides an imaging device capable of reducing illumination light as unnecessary light incident on an imaging element when illuminating and imaging a subject through an imaging optical system.

The image pickup apparatus as one aspect of the present invention emits an image pickup element that captures the image pickup light incident on the image pickup optical system from the subject and a first polarized light that is the illumination light emitted to the subject through the image pickup optical system. The illumination light is imaged by reflecting one of the light source system and the second polarized light as the imaging light whose polarization directions are different from those of the first polarized light and the first polarized light and transmitting the other. A polarization separation element that directs the imaging light from the imaging optical system toward the system and is arranged between the polarization separation element and the imaging element to transmit the second polarized light and to transmit the first polarization. It is characterized by having a polarizing element that blocks light. A camera system including the image pickup device and a rotation unit for rotating the image pickup device also constitutes another aspect of the present invention.

According to the present invention, it is possible to illuminate and image a subject through an imaging optical system while reducing unnecessary light incident on the imaging element among the illumination lights.

The exploded perspective view which shows the structure of the surveillance camera provided with the image pickup apparatus of Example 1. FIG. The block diagram which shows the structure of the image pickup apparatus of Example 1. FIG. The figure which shows the reflected light path in the polarization beam splitter of the conventional and Example 1 image pickup apparatus. It is an exploded perspective view of the image pickup apparatus of Example 1 and Example 2. The block diagram which shows the structure of the image pickup apparatus of Example 2. FIG.

Hereinafter, examples of the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration of a surveillance camera system including the image pickup apparatus 4 according to the first embodiment of the present invention. The image pickup device 4 is held by a pan-tilt rotation unit 5 as a rotation unit. The pan-tilt rotation unit 5 changes the imaging direction of the imaging device 4 by rotating the imaging device 4 in the pan, tilt, and rotation directions. The image pickup device 4 is covered with a dome cover 3 attached to the pan-tilt rotation unit 5 by a holding ring 2 and a plurality of screws 1.

FIG. 2 shows the configuration of the image pickup apparatus 4 of this embodiment. The image pickup apparatus 4 includes an image pickup optical system 9, an image pickup element 11, a light source 6, a polarization beam splitter 8, a first polarization element 7, and a second polarization element 10.

The imaging optical system 9 has a fixed lens 12, a first zoom lens 13, an aperture 19, a second zoom lens 14, and a focus lens 15 in this order from the subject side. The first and second zoom lenses 13 and 14 move in the optical axis direction of the imaging optical system 9 to perform zooming. The first zoom lens 13 is driven by the first zoom motor 16, and the second zoom lens 14 is driven by the second zoom motor 17.

The aperture 19 adjusts the amount of light by changing its aperture diameter. The diaphragm 19 is driven by the diaphragm drive unit 20. The focus lens 15 moves in the optical axis direction to perform focusing. The focus lens 15 is driven by the focus motor 18. The first zoom motor 16, the second zoom motor 17, the aperture drive unit 20, and the focus motor 18 are instructed by a personal computer (PC) 23 as an external controller via a network (LAN, Internet, etc.) (not shown). It is controlled by the received camera control unit 22. The imaging optical system 9 may be interchangeable (detachable) with respect to the imaging device 4.

The image pickup element 11 is composed of photoelectric conversion elements such as a CCD sensor and a CMOS sensor, and captures (photoelectrically converts) a subject image formed by the imaging light incident on the imaging optical system 9 from a subject (not shown). The image pickup signal from the image pickup device 11 is input to the camera control unit 22. The camera control unit 22 converts an imaging signal as an analog signal into a digital signal, and performs various image processing on the digital signal to generate image data. The image data is transmitted to the PC 23 via the network, and is displayed or recorded on the monitor on the PC 23.

The light source 6 has a light emitting element such as an LED and emits illumination light. The lighting / extinguishing of the light source 6 and the amount of light emitted are controlled by the lighting control unit 21 that receives an instruction from the camera control unit 22. The illumination light emitted from the light source 6 may be a visible light source such as white light or monochromatic light, or may be infrared light.

A polarization beam splitter 8 having a polarization separation surface as an optical path separation surface is arranged on an optical path between the image pickup optical system 9, the image pickup element 11, and the light source 6. A first polarizing element 7 is arranged between the polarizing beam splitter 8 and the light source 6, and a second polarizing element 10 is arranged between the polarizing beam splitter 8 and the image sensor 11.

The first polarizing element 7 is a polarization conversion element that converts unpolarized light as illumination light from the light source 6 into S-polarized light. The polarization conversion element emits S-polarized light of unpolarized light as it is, and rotates the polarization direction of P-polarized light, which has a different polarization direction from S-polarized light, by a phase plate to emit it as S-polarized light. The light source system LS is composed of the light source 6 and the first polarizing element (polarization conversion element) 7.

When the light source 6 emits linearly polarized light like a laser element, it is not necessary to provide the first polarizing element 7. In this case, the light source 6 constitutes the light source unit.

The polarization beam splitter 8 as a polarization separation element is a plate-type polarization beam in which a polarization separation surface is provided on a plate-shaped or film-like translucent substrate (parallel flat plate) by a wire grid structure, a metal vapor deposition film, a dielectric film, or the like. It is a splitter. The polarized beam splitter (polarized light separation surface) 8 has a property of reflecting S-polarized light as the first polarized light (linearly polarized light) and transmitting P-polarized light as the second polarized light (linearly polarized light).

The second polarizing element 10 is a polarizing plate having a property of transmitting P-polarized light and reflecting or absorbing S-polarized light and not transmitting (blocking) the S-polarized light. That is, the second polarizing element 10 is arranged so that the directions of the first polarizing element 7 and the polarization axis are orthogonal to each other.

Of the imaging light as unpolarized light that has entered the imaging optical system 9 from the imaging region on the subject side and passed through the imaging optical system 9, P-polarized light passes through the polarizing beam splitter 8 and further, the second polarizing element 10. And reaches the image pickup element 11. As a result, the subject image formed by the imaging light as P-polarized light is imaged.

On the other hand, the illumination light as S-polarized light emitted from the light source 6 and transmitted through the first polarizing element 7 is reflected by the polarization beam splitter 8 and passes through the imaging optical system 9 to irradiate the illumination region on the subject side. .. In this way, the polarizing beam splitter 8 transmits the imaging light from the imaging optical system 9 and directs it toward the imaging element 11, and reflects the illumination light from the first polarizing element 7 and directs it toward the imaging optical system 9. In other words, the polarizing beam splitter 8 separates the optical path of the imaging light between the polarizing beam splitter 8 and the imaging element 11 and the optical path of the illumination light between the polarizing beam splitter 8 and the light source 6.

The image pickup apparatus 4 of this embodiment has a mode in which the subject is imaged while illuminating the subject. In this mode, since the imaging light and the illumination light pass through the imaging optical system 9 which is a common optical system, there is little deviation (paralux) between the imaging region and the illumination region. That is, the position and size of the illumination area can be adjusted to the position and size of the imaging area. Further, even when the zoom magnification of the image pickup optical system 9 is changed, the size of the illumination area changes according to the change in the size of the image pickup area, and the paralux is small. Since the illumination light diffusely reflected by the subject (that is, the image pickup light) contains the P polarization component transmitted through the second polarizing element 10, it can reach the image pickup element 11. Therefore, it is possible to simultaneously illuminate and image the subject.

Here, the first polarizing element 7 does not necessarily completely convert unpolarized light into (100%) S-polarized light, and may emit only a few percent of the unpolarized light as unpolarized light. Further, the polarization splitting surface of the polarization beam splitter 8 does not necessarily reflect 100% of S-polarized light, and may transmit leaked light of several% of S-polarized light. At this time, unnecessary light as S-polarized light transmitted through the polarizing beam splitter 8 is reflected directly or inside the image pickup device 4 and directed toward the second polarization element 10 and the image pickup device 11. However, in this embodiment, such unnecessary S-polarized light can be blocked by the second polarizing element 10 so as not to reach the image sensor 11.

It should be noted that the term "not transmitting or blocking S-polarized light" in the second polarizing element 10 is not limited to the case of completely (100%) not transmitting or blocking S-polarized light, but also almost (for example, 95% or more) without transmitting. It also includes the case where only a small part (for example, 5% or less) is transmitted.

Further, in this embodiment, the image pickup device 11 and the second polarizing element 10 which is a separate body from the image sensor 11 are used, but instead of these, a polarizing element having the same function as the second polarizing element 10 is imaged. A polarized image sensor integrally provided on the element may be used. In this case as well, it is considered that the polarizing element is arranged between the polarizing beam splitter (polarization separation surface) and the image pickup device.

Further, the light source 6 and the image pickup device 11 may be arranged so as to have an optically conjugate relationship with the polarization beam splitter 8. As a result, it is possible to prevent a part of the illumination light (unnecessary light) from passing outside the original illumination optical path and being reflected inside the image pickup apparatus 4 toward the image pickup device 11. However, as will be described in detail later, it is preferable that the light source 6 and the image sensor 11 are arranged so as to be displaced from each other in an optically conjugate relationship with the polarizing beam splitter 8.

Further, the light source 6 may be provided with an optical system for collimating the illumination light. As a result, the incident angle of the illumination light incident on the first polarizing element 7 is unified, and the conversion of the first polarizing element 7 to S-polarized light can be performed better. Further, the second polarizing element 10 can also block S-polarized light satisfactorily. When collimated light is used, it is preferable that the light emitting area of the light source 6 is the same as the image pickup area of the image pickup device 11.

Further, in order to prevent the light source 6 from becoming long in the direction of the polarizing beam splitter 8, a reflecting surface such as a mirror may be provided inside the light source 6 or between the light source 6 and the polarizing beam splitter 8.

Further, the λ / 4 plate is arranged between the imaging optical system 9 and the polarizing beam splitter 8 or at a position closer to the subject than the imaging optical system 9, and the illumination light transmitted back and forth through the λ / 4 plate is the second illumination light. The image may be taken through the polarizing element 10.

As described above, the reason why it is preferable to displace the light source 6 and the image sensor 11 with respect to the polarizing beam splitter 8 from an optically conjugate relationship will be described. In FIG. 2, reference numeral 24 denotes a point (hereinafter referred to as a separation point) where the optical axes of the imaging optical system 9 intersect on the polarization separation surface of the polarization beam splitter 8. When the light source 6 and the image sensor 11 are arranged so as to be offset from each other in an optically conjugate relationship with the polarizing beam splitter 8, the optical path length Ll between the separation point 24 and the light source 6 is set between the separation point and the image sensor 11. It is different from the optical path length between them, that is, it is lengthened (Ll> Ls) or shortened (Ll <Ls).

In an image pickup device in which the optical system is shared by the projector function and the image pickup function as in the conventional case, the image pickup element and the display element are arranged at positions optically conjugate with respect to the polarization separation surface in order to obtain a clear projection image. do. However, the image pickup apparatus 4 of this embodiment has a lighting function and an image pickup function that are not projector functions. When the illumination light emitted from the light source 6 in the image pickup apparatus 4 is not uniform light, the light source 6 and the image pickup element 11 are illuminated when they are optically conjugate to the polarization separation surface (polarization beam splitter 8). The unevenness of light appears in the illumination area as it is. On the other hand, by arranging the light source 6 and the image sensor 11 so as to be offset from the position conjugate with respect to the polarizing beam splitter 8, it is possible to prevent unevenness of the illumination light from appearing in the illumination region.

Further, it is preferable that the image sensor 11 and the first polarizing element 7 are arranged so as to be offset from the position optically conjugate with the polarizing beam splitter 8. That is, the optical path length Lp between the separation point 24 and the first polarizing element 7 is made different from the optical path length Ls between the branch point 24 and the image sensor 11 (Lp> Ls or Lp <Ls). Is preferable. When the image sensor 11 and the first polarizing element 7 are arranged at a position conjugate with respect to the polarizing beam splitter 8, the shadow of illumination generated by dust or scratches on the first polarizing element 7 is projected onto the subject. In particular, when the shadow of the illumination is the same as the size of the subject, the accuracy of image processing such as face recognition and object detection using the image data obtained by imaging may decrease.

Therefore, by arranging the image sensor 11 and the first polarizing element 7 so as to be offset from the position conjugate with respect to the polarizing beam splitter 8, the shadow of the illumination generated by dust or scratches on the first polarizing element 7 is generated. Can be prevented from being projected onto the subject.

Further, in this embodiment, when the light source 6 is within the diameter range of the imaging optical system 9, Ll> Ls or Lp> Ls is preferable. As a result, the length of the image pickup device 4 in the optical axis direction can be shortened, and the range in which the image pickup device 4 rotates when tilted can be reduced. As a result, the dome cover 3 shown in FIG. 1 can be made smaller, and the entire surveillance camera can be made smaller.

However, when the light source 6 includes a light-shielding member such as a mask, a lens, or the like and the light source 6 becomes longer in the direction of the polarizing beam splitter 8, Ls> Ll or Ls in order to shorten the length of the light source 6. > Lp is preferable.

Next, in this embodiment, the reason why the polarization beam splitter (polarization separation surface) 8 is used for optical path separation will be described. First, since most of the illumination light transmitted through the first polarizing element 7 can be guided to the imaging optical system 9, the polarization separation surface uses an optical path separation surface such as a half mirror that separates the incident light in half. Lighting efficiency and imaging efficiency can be improved as compared with the case. Secondly, when the polarization separation surface is used, the illumination light (unnecessary light) that is not guided to the image pickup optical system 9 is reduced, so that the reflection of unnecessary light inside the image pickup apparatus 4 is reduced and the image sensor 11 is unnecessary. The incident of light can be effectively suppressed.

Further, in this embodiment, the reason why a plate-type polarizing beam splitter having a polarizing separation surface formed on a plate-shaped or film-shaped substrate is used as the polarizing beam splitter 8 will be described. In FIGS. 3A and 3B, the illumination light as unpolarized light that was not converted into S-polarized light by the first polarizing element 7 is split into the polarization separation surfaces 8a between the cube-shaped prisms 8b'and 8c'. The case where ′ is formed is incident on the cube-type polarized beam splitter 8 ′ is shown.

In FIG. 3A, a part of the P-polarized light component reflected by the polarization separation surface 8a'of the unpolarized light incident on the prism 8b'is internally reflected by the emission surface of the prism 8b' and is reflected on the polarization separation surface 8a'. It returns to, and is transmitted to the image pickup element side as unnecessary light. Further, in FIG. 3B, of the unpolarized light incident on the prism 8b', the P-polarized light component transmitted through the polarization separation surface 8a'is internally reflected by the prism 8c', returns to the polarization separation surface 8a', and is reflected there. The light is directed toward the image pickup element as unnecessary light. The unnecessary light as P-polarized light passes through the second polarizing element 10 and reaches the image sensor 11.

On the other hand, FIG. 3C shows a plate-type polarizing beam in which unpolarized light that has not been converted into S-polarized light by the first polarizing element 7 has a polarization separation surface 8a formed on a plate-shaped or film-shaped substrate 8b. The case where the light is incident on the splitter 8 is shown. In FIG. 3C, most of the P-polarized light component as unnecessary light in the unpolarized light passes through the polarization separation surface 8a and is internally reflected by the substrate 8a toward the imaging optical system side. That is, by using the plate-type polarizing beam splitter 8, it is possible to prevent unnecessary light as reflected light generated inside the plate-type polarizing beam splitter 8 from heading toward the second polarizing element 10 and the image pickup device 11.

When the plate-type polarizing beam splitter 8 is used, the light transmitted through the substrate is refracted and the thicker the substrate, the larger the astigmatism. Therefore, it is preferable to make the substrate 8b as thin as possible.

FIG. 4A shows the image pickup apparatus 4 of this embodiment in an exploded manner. Reference numeral 25 denotes a lens barrel including the imaging optical system 9. Reference numeral 28 denotes a polarization separation unit including a polarization beam splitter 8 and a holding member for holding the polarization beam splitter 8. Reference numeral 27 denotes a first polarizing element 7 unit including a first polarizing element 7 and a holding member for holding the first polarizing element 7, and 29 is a second polarized light including a second polarizing element 10 and a holding member for holding the second polarizing element 10. It is an element unit. Reference numeral 30 denotes an image sensor unit including an image sensor 11, a substrate on which the image sensor 11 is mounted, and a holding member for holding the substrate.

The image pickup device 4 of this embodiment has a space 31 provided on the side opposite to the light source 6 sandwiching the polarization separation unit 28 in the assembled state of the image pickup device 4 shown in FIG. Further, a diffuse reflection surface 31b is provided on the side opposite to the polarization separation unit 28 sandwiching the space 31.

Unwanted light emitted from the first polarizing element 7 and transmitted through the polarizing beam splitter 8 passes through the space 31 and is diffusely reflected by the diffuse reflection surface 31b. If the space 31 is not provided and unnecessary light is diffusely reflected on the surface 31a close to the polarizing beam splitter 8 and its polarization state is disrupted, at least a part thereof is directly reflected by the polarizing beam splitter 8 or the first. There is a possibility that the polarizing element 10 is directed toward the polarizing element 10 and is transmitted through the polarizing element 10 to be incident on the imaging element 11.

Therefore, in this embodiment, the diffuse reflection surface 31b can be separated from the polarization beam splitter 8 by providing the diffuse reflection surface 31b with a space 31 sandwiched between the polarization beam splitter 8 and the polarization beam splitter 8. That is, the optical path length until unnecessary light emitted from the polarizing beam splitter 8 is reflected by the diffuse reflection surface 31b, the optical path length from reflection by the diffuse reflection surface 31b until the return to the polarizing beam splitter 8, and the second polarizing element 10 The length of the optical path until it enters the light can be lengthened. The intensity of light is inversely proportional to the square of the distance according to the inverse square law. As a result, it is possible to reduce the incident of unnecessary light on the image sensor 11. An antireflection structure may be provided on the surface 31a.

Further, in this embodiment, by inclining the diffuse reflection surface 31b toward the imaging optical system with respect to the direction facing the polarizing beam splitter 8, the diffuse reflection surface 31b diffuses and reflects the polarization beam splitter 8 and the image pickup element 11. It reduces unnecessary light toward. Further, in this embodiment, a diffuse reflection surface 31c that stands up against the diffuse reflection surface 31b is provided at the end of the space 31 on the image pickup element side, and the second unnecessary light diffusely reflected by the diffuse reflection surface 31b is directly second. The light directed to the polarizing element 10 is reduced.

The diffuse reflection surface 31b may be a specular reflection surface. When the unwanted light transmitted through the polarizing beam splitter 8 is specularly reflected, the polarized state of the unwanted light is maintained. Therefore, if unnecessary light maintains S polarization, even if it is reflected by the polarization beam splitter 8, it is blocked by the second polarizing element 10, and it is possible to suppress the incident light on the image sensor 11. Further, the specular reflection surface may be provided at the position of the surface 31a without providing the space 31.

As described above, according to the present embodiment, it is possible to illuminate and image a subject through the image pickup optical system 9 while reducing unnecessary light incident on the image pickup element 11 among the illumination lights.

FIG. 5 shows the configuration of the image pickup apparatus 4', which is the second embodiment of the present invention. In this embodiment, the components common to those in the embodiment are designated by the same reference numerals as those in the first embodiment. The image pickup apparatus 4'of this embodiment has a configuration in which the positions of the light source 6 and the first polarizing element 7'and the positions of the image pickup element 11 and the second polarizing element 10' are interchanged with respect to the first embodiment. .. The first polarizing element 7'converts the illumination light as unpolarized light emitted from the illumination unit 6 into P-polarized light (first polarized light) and emits it. On the other hand, the second polarizing element 10'has a property of transmitting S-polarized light (second polarized light) and absorbing or reflecting P-polarized light so as not to transmit (block) it. Other configurations are the same as in the first embodiment.

Of the imaging light as unpolarized light that has entered the imaging optical system 9 from the imaging region on the subject side and passed through the imaging optical system 9, S-polarized light is reflected by the polarizing beam splitter 8 and further, the second polarizing element 10 It passes through ′ and reaches the image pickup element 11. As a result, the subject image formed by the imaging light as S-polarized light is imaged. On the other hand, the illumination light emitted from the light source 6 and converted into P-polarized light by the first polarizing element 7'transmits the polarization beam splitter 8 and passes through the imaging optical system 9 to irradiate the illumination region on the subject side. NS.

The imaging device 4'of this embodiment also has a mode in which the subject is imaged while illuminating the subject. In this mode, since the imaging light and the illumination light pass through the common imaging optical system 9, there is little paralux between the imaging region and the illumination region. Since the illumination light diffusely reflected by the subject (that is, the image pickup light) contains the S polarization component transmitted through the second polarizing element 10', it can reach the image pickup element 11. Therefore, it is possible to simultaneously illuminate and image the subject.

Further, the first polarizing element 7'does not necessarily completely convert the illumination light as unpolarized light into (100%) P-polarized light, and may emit only a few percent of the unpolarized light as unpolarized light. Further, the polarization splitting surface of the polarization beam splitter 8 does not necessarily transmit 100% of P-polarized light, and may reflect several% of P-polarized light. At this time, unnecessary light as P-polarized light reflected by the polarizing beam splitter 8 is reflected directly or inside the image pickup apparatus 4'and heads toward the second polarization element 10'and the image pickup device 11. However, in this embodiment, such unnecessary P-polarized light can be blocked by the second polarizing element 10'to prevent the image sensor 11 from being reached.

The relationship between Ll, Ls, and Lp in this example is the same as in Example 1. Further, in this embodiment as well, a plate-type polarizing beam splitter is used as the polarizing beam splitter 8. In this embodiment as well, the illumination light is refracted when it passes through the substrate of the polarizing beam splitter 8, but astigmatism is unlikely to occur.

FIG. 4B shows the image pickup apparatus 4'of this embodiment in an exploded manner. The image pickup device 4'of this embodiment has a space 31'provided on the side opposite to the image pickup device unit 30 sandwiching the polarization separation unit 28 in the assembled state of the image pickup device 4'shown in FIG. Further, a diffuse reflection surface 31b'is provided on the side opposite to the polarization separation unit 28 sandwiching the space 31'.

Unwanted light emitted from the first polarizing element 7'and reflected by the polarizing beam splitter 8 passes through the space 31'and is diffusely reflected by the diffuse reflection surface 31b'. Similar to the first embodiment, by providing the diffuse reflection surface 31b'with a space 31'between the polarizing beam splitter 8, the optical path length and the diffuse reflection surface until unnecessary light is reflected by the diffuse reflection surface 31b'. The optical path length from the reflection by 31b'to the incident on the polarizing beam splitter 8 can be lengthened, and the incident of unnecessary light on the image pickup element 11 can be suppressed.

Further, also in this embodiment, as in the first embodiment, the diffuse reflection surface 31b'is inclined toward the imaging optical system with respect to the direction facing the polarizing beam splitter 8, and the diffuse reflection surface is at the end of the space 31 on the image pickup element side. A diffuse reflection surface 31c'that stands up against 31b' is provided. Further, as in the first embodiment, the diffuse reflection surface 31b'may be a specular reflection surface, or the specular reflection surface may be provided on the surface 31a' close to the polarizing beam splitter 8 without providing the space 31'.

Also in this embodiment, it is possible to illuminate and image the subject through the image pickup optical system 9 while reducing unnecessary light incident on the image sensor 11 among the illumination lights.

Each of the above-described examples is only a representative example, and various modifications and changes can be made to each of the examples in carrying out the present invention.

6 Lighting unit 7 First polarizing element 8 Polarizing beam splitter 9 Imaging optical system 10 Second polarizing element 11 Imaging element

Claims (9)

An image sensor that captures the imaging light incident on the imaging optical system from the subject,
A light source system that emits a first polarized light that is an illumination light that is applied to the subject through the imaging optical system.
By reflecting one of the first polarized light and the second polarized light as the imaging light whose polarization direction is different from that of the first polarized light and transmitting the other, the illumination light is transmitted to the imaging optics. A polarization separation element that directs the imaging light from the imaging optical system toward the system and directs the imaging light toward the imaging element.
An image pickup device that is arranged between the polarization separation element and the image pickup element and has a polarization element that transmits the second polarized light and blocks the first polarized light. The imaging device according to claim 1, wherein the subject image is imaged while irradiating the subject with the illumination light. The imaging device according to claim 1 or 2, wherein the light source system includes a light source that emits unpolarized light and a polarization conversion element that converts the unpolarized light into the first polarized light. At least one of the optical path length from the separation point intersecting the optical axis of the imaging optical system to the light source unit and the optical path length from the separation point to the polarization conversion element on the polarization separation surface of the polarization separation element is the separation point. The imaging device according to claim 1, wherein the optical path length from to the imaging element is different from that of the imaging device. The imaging device according to any one of claims 1 to 4, wherein the polarizing separation element is an element in which a polarization separation surface is provided on a plate-shaped or film-shaped translucent substrate. It has a diffuse reflection surface that diffusely reflects unnecessary light that does not go from the polarization separation element to the imaging optical system among the illumination lights.
The invention according to any one of claims 1 to 5, wherein a space for separating the diffuse reflection surface from the polarization separation element is provided between the polarization separation element and the diffusion reflection surface. Imaging device. The imaging device according to claim 6, wherein the diffuse reflection surface is inclined toward the imaging optical system. The imaging device according to any one of claims 1 to 5, further comprising a specular reflection surface that specularly reflects unnecessary light that does not direct from the polarization separating element to the imaging optical system among the illumination lights. The imaging device according to any one of claims 1 to 8.
A camera system including a rotating unit for rotating the image pickup device.

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