JP2006184844A - Image forming optical system and imaging apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming optical system capable of forming the images of a plurality of subjects to be inspected which are separated in the optical axis direction on the same image forming surface at the same time while maintaining a sufficient resolution. <P>SOLUTION: Between the subject to be inspected and the image forming surface, optical elements which are divided into a plurality of regions having different refractive powers from one another are arranged, wherein the plurality of regions are respectively arranged on different positions in the optical axis direction. Thereby, images of the plurality of subjects which are separated in the optical axis direction can be connected on the image forming surface at the same time. Otherwise, between the subject to be inspected and the image forming surface, a transparent parallel flat plate is arranged so as to allow a part of light from the subject to be inspected to pass through the same. Thereby, the images of the plurality of subjects to be inspected which are separated by distances in accordance with thicknesses and refractive indexes of the parallel flat plate can be connected on the image forming surface at the same time. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an imaging optical system that forms an image of a subject on an imaging surface and an imaging apparatus using the imaging optical system.

  An imaging device that images and inspects the front and back surfaces of a transparent object, internal scratches, defects, and the like is connected by an imaging optical system that forms an image of a subject on the imaging surface. An imaging device that captures an image formed on the image plane is incorporated. In such an imaging apparatus, for example, when imaging a plurality of subjects positioned apart from each other in the optical axis direction, such as images of the front and back surfaces of parallel flat glass or a cross section parallel to these, an imaging lens Must be refocused for each subject (surface or cross section) to be examined (imaged) by moving the lens in the direction of the optical axis. Alternatively, instead of moving the imaging lens in the direction of the optical axis as described above, a transparent parallel plate member is attached to a rotating disk, and this is taken in and out of the optical path of the imaging optical system, and passes through the parallel plate. There is also known one that fluctuates the focus position by utilizing the refraction action of light (for example, see Patent Documents 1 and 2 below).

There is also a need for a technique for imaging a plurality of subjects at the same time on the same imaging plane instead of imaging each of a plurality of subjects separated in the optical axis direction as described above. It has been. This includes a degree (the reciprocal of the focal length) within the effective aperture of the lens, such as a progressive focus lens (see Patent Document 3 below) and a multifocal lens (see Patent Document 4 below) applied to eyeglass lenses. A lens in which a plurality of different lenses are incorporated, or a zone plate having multiple concentric ring-shaped regions whose degrees change from the central part to the peripheral part of the effective diameter of the imaging optical system, multiple concave reflecting mirrors, etc. Is known as an imaging lens. It is also possible to simultaneously image and image a plurality of objects separated in the optical axis direction by narrowing the aperture stop to increase the depth of field.
JP-A-4-315906 Japanese Patent Laid-Open No. 8-304043 JP-A-6-313866 JP-A-6-214198

  However, when a plurality of subjects separated in the optical axis direction were imaged through a plurality of lenses having different degrees (reciprocal of focal length), the image size was different for each subject. There is a drawback that the image (image quality) becomes unnatural. In addition, when imaging is performed with the aperture stop narrowed down (increasing the depth of field), the amount of incident light (numerical aperture) from the subject to the imaging optical system is reduced, so the resolution is reduced and finer. There has been a problem that it is difficult to detect scratches and defects.

  The present invention has been made in view of such problems, and simultaneously forms a plurality of subjects separated in the optical axis direction on the same image plane while maintaining sufficient image quality and resolution. It is an object of the present invention to provide an imaging optical system having a configuration capable of achieving the above and an imaging apparatus using the same.

  In order to achieve such an object, an imaging optical system according to a first aspect of the present invention is an imaging optical system that forms an image of a subject on an imaging surface. A transparent parallel plate member interposed therebetween, and a part of the light that exits from the subject and is collected on the imaging plane passes through the parallel plate member. And an image of another subject separated from the subject in the optical axis direction by a distance corresponding to the thickness and refractive index of the parallel plate member are formed on the imaging plane at the same time. It is characterized by that.

  An imaging optical system according to a second aspect of the present invention is the imaging optical system according to the first aspect, wherein the parallel plate member is formed of a plurality of segments arranged side by side in a circumferential direction centering on the optical axis. It consists of coupling | bonding, The thickness and / or refractive index of each of these segments differ from each other.

  An imaging optical system according to a third aspect of the present invention is the imaging optical system according to the first or second aspect, wherein the parallel plate member is rotatable about the optical axis.

  An imaging apparatus according to a fourth aspect of the invention includes the imaging optical system according to any one of the first to third aspects, and an imaging device that captures an image formed on the imaging surface. It is structured.

  An imaging apparatus according to a fifth aspect of the present invention is the imaging apparatus according to the fourth aspect, wherein the imaging optical system has an aperture stop, and the parallel plate member constituting the imaging optical system is an aperture stop. It is provided in the vicinity position.

In the imaging apparatus according to a sixth aspect of the present invention, the parallel plate member and one or a plurality of optical elements other than the parallel plate member constituting the imaging optical system are configured as modules that can be separated from each other. Is characterized in that the arrangement can be changed with respect to the optical axis of the imaging device.
The imaging optical system according to claim 7 includes an optical element divided into a plurality of regions having different refractive powers between the subject and the imaging surface, and the plurality of regions have different positions in the optical axis direction. A plurality of light beams that are separated from each other in the optical axis direction by passing a part of the light that exits from the subject and is collected on the imaging surface through the optical element. An imaging optical system characterized in that an image is formed on the imaging plane simultaneously with an image of a subject.

  According to the imaging optical system of the present invention, it is possible to simultaneously combine images of a plurality of subjects separated in the optical axis direction on the same imaging plane without causing a decrease in light quantity (numerical aperture) and resolution. Can do. In addition, according to the imaging apparatus according to the present invention, it is possible to obtain an image of the image with high resolution and good image quality.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an imaging apparatus 1 according to the first embodiment of the present invention. The imaging apparatus 1 captures images of two subjects Q1 and Q2 (assumed that the subject Q1 is located on the imaging lens 2 side) that are spaced apart by a distance z ₀ on the optical axis AX. And a light source (not shown) that irradiates light to the subjects Q1 and Q2, and an imaging plane 4 (imaging surface of the imaging device 5 described later) that emits light from the subjects Q1 and Q2 irradiated by the light source. An imaging lens (imaging lens) 2 that condenses on the top, and an insertion plate (thickness d ₁ , refractive index n) made of a transparent parallel plate member interposed between the subjects Q1 and Q2 and the imaging lens 2 ₁ ) 3 and an image pickup device 5 (for example, a CCD camera) for picking up an image formed on the image plane 4. Of the elements constituting the imaging apparatus 1, the imaging lens 2 and the insertion plate 3 are an imaging optical system that forms images of the subjects Q1 and Q2 on the imaging surface 4, and according to the present invention. It corresponds to an imaging optical system.

  As can be seen from FIGS. 1 and 2, the insertion plate 3 has a semi-disc shape (a shape obtained by halving the disc), and its central axis (an axis corresponding to the central axis of the disc) is the optical axis AX. It is provided so that it may correspond substantially. Although the imaging lens 2 is shown here as a single lens, it may be configured by combining a plurality of lenses (the same applies to other embodiments described later).

The relative positions of the imaging lens 2 and the imaging plane 4 (of the imaging device 5) with respect to the subjects Q1 and Q2 can be freely set. In order to image the subjects Q1 and Q2 by the imaging apparatus 1, first, an image of the subject Q1 is formed at a point P on the imaging plane 4 in a state where the insertion plate 3 is removed from the imaging apparatus 1. As described above, the positions of the imaging lens 2 and the imaging plane 4 with respect to the subject Q1 are adjusted. At this time, the optical path of the light exiting from the position A ₁ of the subject Q1 on the optical axis AX and condensed on the imaging plane 4 is the optical path A ₁ → A shown in the region above the optical axis AX in FIG. ₄ → Inside the imaging lens 2 → A ₅ → P

Subsequently, when the insertion plate 3 is inserted and installed between the subject Q1 and the imaging lens 2, a part of the light that exits from the subject Q1 (point A ₁ ) and is condensed on the imaging plane 4 is the insertion plate. 3 will be passed. Since the light passing through the insertion plate 3 is refracted when entering and exiting the insertion plate 3 in this way, it is not collected at the point P. Instead, it is separated from the subject Q1 by the distance z in the optical axis AX direction. The part of the light emitted from the point C ₀ on the optical axis AX (separated away from the imaging lens 2) passes through the insertion plate 3 and forms an image at a point P on the imaging plane 4. Become. At this time, the optical path of the light exiting from the point C ₀ and condensed on the imaging plane 4 is the optical path C ₀ → B ₂ → inside the insertion plate 3 → B shown in the region below the optical axis AX in FIG. ₃ → B ₄ → in the imaging lens 2 → B ₅ → P.

Here, the thickness of the insert plate 3 inserted between the object Q1, Q2 and the imaging lens 2 (d ₁₎ and refractive index (n _1), describe the relationship between the distance z.

As shown in FIG. 2, the light emitted from the point C ₀ advances from C ₀ → B ₂ and enters the insertion plate 3, and the light incident on the insertion plate 3 is refracted at the time of incidence and passes through the insertion plate 3. After proceeding from _{2 to} B ₃ , the light is further refracted when exiting from the insertion plate 3, proceeds from B _{3 to} B _4, and enters the imaging lens 2. Here, the point where the straight line extending from the optical path B ₃ -B ₄ to the B ₃ side intersects the optical axis AX coincides with the point A ₁ (the light passing through the optical path B ₃ -B ₄ passes through the optical path A ₁ -A ₄ . The length of the line segment C ₀ A ₁ is as follows from the law of refraction in a parallel plate:
C ₀ A ₁ = (1-1 / n ₁ ) d ₁ (1)
It becomes. Also, since the length of the line segment C ₀ A ₁ is equal to the distance z,
z = (1-1 / n ₁ ) d ₁ (2)
It can be expressed as.

Here, the thickness (d ₁ ) and refractive index (n ₁ ) of the insertion plate 3 change, and the relational expression z ₀ = (1-1 / n ₁ ) d ₁ where z = z ₀ in the above equation (2). (3)
If the above condition is satisfied, the image of the subject Q1 and the image of the subject Q2 positioned at a distance z ₀ away from the subject Q1 in the optical axis AX direction are simultaneously formed on the imaging plane 4. Imaged. Then, if the image projected on the imaging surface 4 is picked up by the image pickup device 5, the images of both the subjects Q1 and Q2 can be obtained simultaneously (as the same focus image). Further, the image picked up by the image pickup device 5 is processed by the image processing apparatus 6 shown in FIG. 1 and then visually displayed on the display 7. Since the insertion plate 3 is a transparent parallel plate member having a single thickness and refractive index, the distance z varies regardless of the insertion position in the optical path between the subject Q1 and the imaging lens 2. However, it is advantageous to provide as close as possible to the imaging lens 2 in that the entire imaging device 1 can be made compact.

FIG. 3 shows an imaging apparatus 20 according to the second embodiment of the present invention. This imaging device 20 has a surface (a surface on the side facing the imaging lens 2) of a parallel flat glass (thickness d ₀ , refractive index n ₀ ) 8 made of a transparent material placed perpendicular to the optical axis AX. , A reference plane S1) and a plane separated from the reference plane S1 by a distance z 'along the optical axis AX (the back surface of the parallel flat glass 8 or a cross section between the front and back surfaces, hereinafter referred to as a reference surface S2). ) Is taken as an object to be imaged. The imaging apparatus 20 according to the second embodiment differs from the imaging apparatus 1 according to the first embodiment described above only in the subject, and is the same as the imaging apparatus 1 according to the first embodiment in FIGS. 3 and 4. Components are given the same reference numerals.

In order to image the two surfaces S1 and S2 by the imaging device 20, first, in a state where the insertion plate 3 is removed from the imaging device 20, a point on the optical axis AX on the reference plane S1 of the parallel flat glass 8 (A The positions of the imaging lens 2 and the imaging plane 4 with respect to the parallel plate glass 8 are adjusted so that the image ₁ ) is formed at the point P on the imaging plane 4. At this time, the optical path of the light exiting from the point A ₁ and condensed on the imaging plane 4 is the optical path A ₁ → A ₄ → in the imaging lens 2 → A ₅ shown in the region above the optical axis AX in FIG. → P

Subsequently, when the insertion plate 3 is inserted and installed between the parallel flat glass 8 and the imaging lens 2, a part of the light that exits from the point A ₁ and is condensed on the imaging surface 4 passes through the insertion plate 3. It becomes like this. Since the light passing through the insertion plate 3 is refracted when entering and exiting the insertion plate 3 in this way, it is not condensed at the point P. Instead, it is only a distance z ′ from the point A _{1 in the} direction of the optical axis AX. A part of the light emitted from the point B ₀ on the optical axis AX that is separated (separated in the direction away from the imaging lens 2) passes through the insertion plate 3 and forms an image at a point P on the imaging plane 4. become. At this time, the optical path of the light exiting from the point B ₀ and condensed on the image plane 4 is the optical path B ₀ shown in the region below the optical axis AX in FIG. 4 → inside the parallel plate glass 8 → B ₁ → B ₂ → insertion plate 3 → B ₃ → B ₄ → imaging lens 2 → B ₅ → P.

Here, the relationship between the thickness (d ₁ ) and the refractive index (n ₁ ) of the insertion plate 3 inserted between the parallel flat glass 8 and the imaging lens 2 and the distance z ′ will be described.

As shown in FIGS. 4 and 5, the light emitted from the point B ₀ travels in the parallel flat glass 8 in the order of B ₀ → B ₁ and is emitted from the surface (reference plane S1) of the parallel flat glass 8, and is refracted here. After that, the air travels in the direction of B ₁ → B ₂ and enters the insertion plate 3. The light incident on the insertion plate 3 is refracted at the time of incidence and travels in the insertion plate 3 from B ₂ → B _3, and then is further refracted and travels from B _{3 to} B ₄ when exiting the insertion plate 3. The light enters the lens 2. Here, the point where the straight line extending from the optical path B ₃ -B ₄ to the B ₃ side intersects the optical axis AX coincides with the point A ₁ , and the optical path B ₁ -B ₂ is parallel to the optical path B ₃ -B ₄ . Further, the optical path B ₃ -B ₄ is the same as the optical path (A ₁ → A ₄ ) of the light exiting from the point A ₁ and not passing through the insertion plate 3. Further, if a point where a straight line extending from the optical path B ₁ -B ₂ to the B ₁ side intersects the optical axis AX is C ₀ , this point C ₀ coincides with the point C ₀ in the first embodiment. (1) is satisfied as it is. In the present embodiment, the length of the line segment C ₀ A ₁ and the distance z ′ are
C ₀ A ₁ = z ′ / n ₀ (4)
From the formula (1) and the formula (4),
z ′ = C ₀ A ₁ n ₀ = n ₀ (1-1 / n ₁ ) d ₁ (5)
Is guided.

That is, an insertion plate 3 made of a transparent parallel plate member having a thickness of d ₁ and a refractive index of n ₁ is inserted between the parallel plate glass 8 and the imaging lens 2 and exits from the point A ₁ to form an image plane. 4 so that a part of the light condensed on 4 passes through the insertion plate 3, the image of the point A ₁ on the reference plane S ₁ , the thickness (d ₁ ) of the insertion plate 3 and the refractive index ( n ₁ ) and the image of the point B ₀ that is located apart from the point A _{1 in the} direction of the optical axis AX by the distance z ′ corresponding to the refractive index (n ₀ ) of the parallel flat glass 8 at the same time. 4 is imaged. Then, if the image projected on the imaging surface 4 is picked up by the image pickup device 5, the images of the two surfaces S1 and S2 as the subject can be obtained simultaneously (as images of the same focus). Further, after the image captured by the imaging device 5 is processed by the image processing apparatus 6 shown in FIG. 4, it can be visually displayed on the display 7 as in the case of the first embodiment. Similarly to the case of the first embodiment, it is advantageous to provide the insertion plate 3 as close as possible to the imaging lens 2 in that the entire imaging device 20 can be made compact.

Here, when the distance z ′ coincides with the thickness d ₀ of the parallel flat glass 8, the reference surface S 2 becomes the back surface of the parallel flat glass 8. That is, if z ′ = d ₀ in the above equation (5), the equation d ₀ = n ₀ (1-1 / n ₁ ) d ₁ (6)
Is obtained, and d ₁ = n ₁ d ₀ / {n ₀ (n ₁ −1)} obtained by modifying this equation (6) (7)
An insertion plate 3 having a thickness (d ₁ ) and a refractive index (n ₁ ) satisfying the above relationship is inserted between the parallel flat glass 8 (reference plane S1) and the imaging lens 2 and exits from the point A _1. If a part of the light condensed on the image plane 4 passes through the insertion plate 3, the image of the reference plane S1 of the parallel flat glass 8 (the surface of the parallel flat glass 8) and the reference plane S1. The image on the reference surface S2 (the back surface of the parallel flat glass 8) positioned at a distance d ₀ (the thickness d ₀ of the parallel flat glass 8) in the optical axis AX direction is simultaneously formed with the image plane 4 Is imaged. Then, if the image projected on the image plane 4 is picked up by the image pickup device 5, images on both the front and back surfaces of the parallel flat glass 8 can be obtained simultaneously (as images of the same focus).

FIG. 6 shows an imaging apparatus 30 according to the third embodiment of the present invention. The imaging device 30 includes a reference plane S1 in the parallel flat glass 8 shown in the second embodiment described above, and a first reference plane (parallel flat glass that is separated from the reference plane S1 by a distance z ₂₁ along the optical axis AX. 8 of the cross-section) S21, and the second reference surface (cross section of the parallel flat glass 8) S22 spaced by a distance z ₂₂ from the reference plane S1 along the optical axis AX, the distance from the reference plane S1 along the optical axis AX z ₂₃ is intended only for capturing the image spaced a (section or rear surface of the parallel flat glass 8) S23 third reference surface as the subject (see also FIG. 8). The imaging apparatus 20 according to the third embodiment is different from the imaging apparatus 20 according to the second embodiment described above only in the insertion plate (reference numeral 23), and the second embodiment is shown in FIGS. The same components as those of the imaging device 20 are denoted by the same reference numerals.

As shown in FIG. 7, the insertion plate 33 in the third embodiment has three segments arranged in a circumferential direction centered on the optical axis AX, that is, a first segment D1 (thickness d). ₂₁ , refractive index n ₂₁ ), second segment D 2 (thickness d ₂₂ , refractive index n ₂₂ ), and third segment D 3 (thickness d ₂₃ , refractive index n ₂₃ ). Each segment D1, D2, D3 has a different thickness and refractive index. The insertion plate 33 is manufactured by a fan-shaped member having a thickness d ₂₁ and a refractive index n ₂₁ (a member corresponding to the first segment D1) and a fan-shaped member having a thickness d ₂₂ and a refractive index n ₂₂ (first member). a member) corresponding to 2 segments D2, sector member (member corresponding to the third segment D3 has a thickness d ₂₃ and refractive index n ₂₃₎ and is constructed are joined to match the apex angle.

In such an imaging device 30, in order to perform imaging of the four surfaces S 1, S 21, S 22, and S 23 on the parallel flat glass 8, first, the parallel plate glass 8 is removed with the insertion plate 33 removed from the imaging device 30. Position adjustment of the imaging lens 2 and the imaging plane 4 with respect to the parallel plate glass 8 is performed so that an image of the point (A ₁ ) on the optical axis AX on the reference plane S1 is focused on the point P on the imaging plane 4. Do. At this time, the optical path of the light exiting from the point A ₁ and condensed on the imaging plane 4 is the optical path A ₁ → A ₄ → imaging lens 2 shown in the region above the optical axis AX in FIG. Inner → A ₅ → P.

Subsequently, when the insertion plate 33 is inserted and installed between the parallel plate glass 8 and the imaging lens 2, a part of the light that is collected from the point A ₁ and focused on the imaging surface 4 is the first of the insertion plate 33. Although the image is not formed on the imaging plane 4 because it passes through the segment D1 (the reason is the same as in the case of the second embodiment), instead, it is separated from the point A ₁ by the distance z _{21 in the} optical axis AX direction ( A part of the light emitted from the point B _{01 (} separated in the direction away from the imaging lens 2) is imaged at a point P on the imaging plane 4. At this time, the optical path of the light exiting from the point B ₀₁ and condensed on the imaging plane 4 is the optical path B ₀₁ shown in the region below the optical axis AX in FIG. B ₁₁ → B ₂₁ → inside the insertion plate 33 → B ₃ → B ₄ → in the imaging lens 2 → B ₅ → P.

Similarly, a part of the light exiting from the point A ₁ and condensed on the imaging plane 4 passes through the second segment D2 of the insertion plate 33 and is no longer imaged on the imaging plane 4. Instead, a part of the light emitted from the point B ₀₂ separated from the point A ₁ by the distance z _{22 in the} optical axis AX direction (separated in the direction away from the imaging lens 2) is connected to the point P on the imaging plane 4. Be imaged. At this time, the optical path of the light emitted from the point B ₀₂ is the optical path B ₀₂ shown in the region below the optical axis AX in FIG. 8B → the parallel plate glass 8 → B ₁₂ → B ₂₂ → the insertion plate 33. → B ₃ → B ₄ → in the imaging lens 2 → B ₅ → P Similarly, a part of the light exiting from the point A ₁ and condensed on the imaging plane 4 passes through the third segment D 3 of the insertion plate 33, so that it does not form an image on the imaging plane 4. Instead, a part of the light emitted from the point B ₀₃ separated from the point A ₁ by the distance z _{23 in the} direction of the optical axis AX (separated in the direction away from the imaging lens 2) becomes a point P on the image plane 4. An image is formed.
At this time, the optical path of the light emitted from the point B ₀₃ is the optical path B ₀₃ → inside the parallel plate glass 8 → B ₁₃ → B ₂₃ → inside the insertion plate 33 shown in the region below the optical axis AX in FIG. → B ₃ → B ₄ → in the imaging lens 2 → B ₅ → P

Here, the relationship between the thickness (d ₂₁ ) and the refractive index (n ₂₁ ) of the first segment D1 of the insertion plate 33 inserted between the parallel flat glass 8 and the imaging lens 2 and the distance z ₂₁ , second Relationship between the thickness (d ₂₂ ) and refractive index (n ₂₂ ) of the segment D2 and the distance z _22, and relationship between the thickness (d ₂₃ ) and refractive index (n ₂₃ ) of the third segment D3 and the distance z ₂₃ State.

As shown in FIG. 8A, the light emitted from the point B ₀₁ travels through the parallel flat glass 8 in the order of B ₀₁ → B ₁₁ and is emitted from the surface (reference plane S1) of the parallel flat glass 8, and is refracted here. After that, the air travels in the air from B _{11 to} B ₂₁ and enters the insertion plate 33. Of the light incident on the insertion plate 33, the light incident on the first segment D1 is refracted at the time of incidence and travels through the first segment D1 from B _{21 to} B _3, and then the insertion plate 33 (first segment D1). The light is further refracted when exiting from the light and proceeds from B _{3 to} B ₄ and enters the imaging lens 2. Here, the point where the straight line extending from the optical path B ₃ -B ₄ to the B ₃ side intersects the optical axis AX coincides with the point A ₁ , and the optical path B ₁₁ -B ₂₁ is parallel to the optical path B ₃ -B ₄ . By setting z ′ = z ₂₁ , n ₁ = n ₂₁ , and d ₁ = d ₂₁ in the above equation (5), the following relational expression is obtained.
z ₂₁ = n ₀ (1-1 / n ₂₁ ) d ₂₁ (8)

Further, as shown in FIG. 8B, the light emitted from the point B ₀₂ travels through the parallel flat glass 8 in the order of B ₀₂ → B ₁₂ and is emitted from the surface (reference plane S 1) of the parallel flat glass 8. After being refracted, the air travels in the air from B _{12 to} B ₂₂ and enters the insertion plate 33. Of the light incident on the insertion plate 33, the light incident on the second segment D2 is refracted at the time of incidence and travels through the second segment D2 from B _{22 to} B _3, and then the insertion plate 33 (second segment D2). The light is further refracted when exiting from the light and proceeds from B _{3 to} B ₄ and enters the imaging lens 2. Here, the point where the straight line extending from the optical path B ₃ -B ₄ to the B ₃ side intersects the optical axis AX coincides with the point A ₁ , and the optical path B ₁₂ -B ₂₂ is parallel to the optical path B ₃ -B ₄ . By setting z ′ = z ₂₂ , n ₁ = n ₂₂ , and d ₁ = d ₂₂ in the above equation (5), the following relational expression is obtained.
z ₂₂ = n ₀ (1-1 / n ₂₂ ) d ₂₂ (9)

Further, as shown in FIG. 8C, the light emitted from the point B ₀₃ travels through the parallel flat glass 8 in the order of B ₀₃ → B ₁₃ and is emitted from the surface of the parallel flat glass 8 (reference plane S1). After being refracted, the air travels in the air from B _{13 to} B ₂₃ and enters the insertion plate 33. Of the light incident on the insertion plate 33, the light incident on the third segment D3 is refracted at the time of incidence and travels through the third segment D3 from B _{23 to} B _3, and then the insertion plate 33 (third segment D3). The light is further refracted when exiting from the light and proceeds from B _{3 to} B ₄ and enters the imaging lens 2. Here, the point where the straight line extending the optical path B ₃ -B ₄ to the B ₃ side intersects with the optical axis AX coincides with the point A ₁ , and the optical path B ₁₃ -B ₂₃ is parallel to the optical path B ₃ -B ₄ . By setting z ′ = z ₂₃ , n ₁ = n ₂₃ , and d ₁ = d ₂₃ in the above equation (5), the following relational expression is obtained.
z ₂₃ = n ₀ (1-1 / n ₂₃ ) d ₂₃ (10)

That is, the first segment D1 thickness of a refractive index n ₂₁ at d _21, a second segment D2 thickness of a refractive index n ₂₂ at d _22, the refractive index thickness at d ₂₃ is n the insert plate 33 comprising a third segment D3 is ₂₃ inserted between the parallel flat glass 8 and the imaging lens 2, the light focused on the imaging surface 4 exits from point a ₁ the thickness of the portion of the first segment D1 of each insert plate 33, by to pass through the second segment D2, and the third segment D3, and the image point a ₁ in the reference plane S1, the first segment D1 An image of a point B ₀₁ located away from the point A _{1 in the} optical axis AX direction by the distance z ₂₁ according to (d ₂₁ ), the refractive index (n ₂₁ ), and the refractive index (n ₀ ) of the parallel flat glass 8. And the thickness (d ₂₂ ) and refractive index (n ₂₂ ) of the second segment D2 and parallel flat glass The image of the point B ₀₂ that is located in the optical axis AX direction away from the point A _{1 by the} distance z ₂₂ according to the refractive index (n ₀ ) of 8, and the thickness (d ₂₃ ) and the refraction of the third segment D3 The image of the point B ₀₃ located at a distance from the point A _{1 in the} direction of the optical axis AX by the distance z ₂₃ corresponding to the refractive index (n ₂₃ ) and the refractive index (n ₀ ) of the parallel flat glass 8 is simultaneously formed. An image is formed on the image plane 4.

  For this reason, if the image projected on the imaging plane 4 as described above is picked up by the imaging device 5, the images of the four planes S1, S21, S22, S23 of the parallel flat glass 8 can be simultaneously (with the same focus). As an image). Further, the image captured by the imaging device 5 can be visually displayed on the display 7 after being processed by the image processing apparatus 6 shown in FIG. 6, as in the case of the second embodiment. Further, as in the case of the second embodiment, it is advantageous to provide the insertion plate 33 as close as possible to the imaging lens 2 in that the entire imaging apparatus 1 can be made compact.

Here, when the distance z ₂₃ coincides with the thickness d ₀ of the parallel flat glass 8, the third reference surface S 23 becomes the back surface of the parallel flat glass 8. That is, if z ₂₃ = d ₀ in the above equation (10), the equation d ₀ = n ₀ (1-1 / n ₂₃ ) d ₂₃ (11)
Can be obtained, d ₂₃ = n ₂₃ d ₀ / {n ₀ (n ₂₃ −1)} obtained by modifying this equation (11) (12)
An insertion plate 33 having a third segment D3 having a thickness (d ₂₃ ) and a refractive index (n ₂₃ ) satisfying the above relationship is inserted between the parallel flat glass 8 (reference plane S1) and the imaging lens 2; If a part of the light exiting from the point A ₁ and condensed on the imaging plane 4 passes through the insertion plate 3, the image of the reference plane S 1 (the surface of the parallel flat glass 8) of the parallel flat glass 8. And an image of the third reference surface S23 (the back surface of the parallel plate glass 8) which is located at a distance d ₀ (the thickness d ₀ of the parallel plate glass 8) in the optical axis AX direction with respect to the reference surface S1. In addition to these, images of two cross sections (a first reference surface S21 having a cross section of z = z ₂₁ and a second reference surface S22 having a cross section of z = z ₂₂ ) positioned between both surfaces S1 and S23 are also simultaneously displayed. Images can be taken (as images with the same focus).

  Further, in the case where one insertion plate 3 has a plurality of segments having different thicknesses and refractive indexes as in the third embodiment, all segments except for one segment selected from them are used. It is preferable to have a configuration in which a mask capable of shielding the light (for example, a rotatable disk having an optical axis AX whose opening is provided only in a portion corresponding to one selected segment) can be inserted and installed. With such a configuration, since only the light transmitted through the selected segment can be condensed on the imaging plane 4, it is confirmed which part of the obtained image is the image of which subject. It becomes possible.

  FIG. 9 shows an image pickup apparatus 40 having an imaging optical system according to the fourth embodiment of the present invention. This imaging device 40 differs from the imaging device 20 according to the second embodiment described above only in its imaging lens (reference numeral 42). The imaging lens 42 is telecentric or double-sided telecentric ( A focusing lens. The biaxial telecentric system does not change the paraxial magnification regardless of the distance at which the image is formed, and the paraxial magnification is always the pupil magnification (reciprocal of the telescope magnification) of this optical system. Therefore, the configuration according to this embodiment has an advantage that the influence on the image plane can be reduced because the same object height is seen even if the position of the subject is slightly shifted in the optical axis AX direction.

  Further, when such an imaging lens 42 is used, when the insertion plate 3 is positioned below the optical axis AX as shown in FIG. 9, the connection is made without passing through the semi-disc-shaped insertion plate 3. The image formed on the image plane 4 is the upper half portion of the reference plane S1 (surface) of the parallel flat glass 8, and is formed on the image plane 4 as the lower half of the image plane that is vertically symmetric with this. An image formed on the imaging plane 4 after passing through the insertion plate 3 is the lower half of the reference plane S1 (cross-section or back side) of the parallel flat glass 8, and is formed on the imaging plane 4 with this. The image is formed as a half on the vertically symmetrical image plane. Therefore, when an image on the imaging plane 4 is captured in this state, the image of the object is synthesized separately by the light rays (light beams) emitted from the upper and lower parts of the separated object, and the entire image is obtained. In the image, the lower half is an image of only the upper half of the reference plane S1 of the parallel flat glass 8, and the upper half is an image of only the lower half of the reference plane S2 of the parallel flat glass 8. Therefore, in the imaging device 40 according to the present embodiment, the insertion plate 3 can be rotated around the optical axis AX, and thus, for example, the insertion plate 3 is positioned below the optical axis AX. First, the imaging device 5 performs the first imaging in the state, and then the imaging device 5 with the insertion plate 3 rotated 180 degrees (with the insertion plate 3 positioned above the optical axis AX). As a result, simultaneous imaging of the entire area of the reference plane S1 and the entire area of the reference plane S1 can be performed. The insertion plate 3 is rotated, for example, by inserting the insertion plate 3 in a cylindrical drum member with external teeth that can rotate about the optical axis AX and then engaging a pinion that meshes with the outside of the drum member. Can be realized by driving with an electric motor or the like.

  FIG. 10 shows an imaging apparatus 50 according to the fifth embodiment, in which the imaging apparatus 40 according to the fourth embodiment is housed in a housing C. However, it is assumed that the imaging lens 42 is composed of a plurality of lenses (the same applies to sixth and seventh embodiments described later). The housing C in the imaging apparatus 50 is composed of a first housing C1 housing the imaging lens 42, a second housing C2 housing the insertion plate 3, and a third housing C3 housing the imaging device 5. It becomes. An aperture stop S for adjusting the amount of light and the like is provided at an intermediate portion of the imaging lens 42, and the insertion plate 3 in the second casing C2 is provided from a plate rotation control device 9 provided outside the casing C. The rotation around the optical axis AX can be controlled. The first casing C1 and the second casing C2 are coupled by the casing coupling means J1, and the first casing C1 and the third casing C3 are coupled by the casing coupling means J2. By doing so, the imaging lens 42 and the insertion plate 3 can be freely attached to and detached from the imaging device 5, and these can be replaced according to the type and size of the subject. For this reason, it is possible to use not only the imaging device 40 according to the fourth embodiment but also the imaging devices 1, 20, and 30 according to other embodiments in a state of being housed in such a casing C (below). The same applies to the sixth and seventh embodiments shown).

  FIG. 11 shows an imaging apparatus 60 according to the sixth embodiment. In the imaging devices 1, 20, 30, 40, and 50 according to the first to fifth embodiments described above, the insertion plate is all a front converter type positioned in front of the imaging lens. However, the imaging according to the sixth embodiment is performed. The device 60 is a rear converter type in which the insertion plate 3 is located behind the imaging lens 42. That is, in this imaging device 60, the first housing C1 that houses the imaging lens 42 in the imaging device 50 according to the fifth embodiment is disposed in front of the second housing C2 that houses the insertion plate 3, and is inserted. In order to increase the distance between the plate 3 and the imaging plane 4 (imaging device 5), an intermediate casing having a hollow inside between the second casing C2 and the third casing C3 as necessary. C4 is interposed. Then, the first casing C1, the second casing C2, and the intermediate casing C4 are coupled in this order by the casing coupling means J1, and the intermediate casing C4 and the third casing C3 are coupled by the casing coupling means J2. Are connected. An aperture stop S for adjusting the amount of light and the like is provided at an intermediate portion of the imaging lens 42, and the insertion plate 3 in the second housing C2 is a plate rotation control device provided outside the housing C. 9, the rotation control around the optical axis AX can be performed.

  Note that even when the insertion plate 3 is inserted and installed behind the imaging lens 42 in this way, the same effect as when the insertion plate 3 is inserted in front of the imaging lens 42 is obtained as shown in FIG. When a semi-disc-shaped insertion plate PL is inserted in front of the lens L, light that has not passed through the insertion plate PL out of the point A on the optical axis AX is condensed at a point P1 on the optical axis AX ( In FIG. 12, the light path indicated by the two-dot chain line in the region above the optical axis AX), the light that passes through the insertion plate PL among the light emitted from the point A is on the optical axis AX and is farther from the point P1. The light is condensed at the point P2 (see the optical path indicated by the solid line in the region below the optical axis AX in FIG. 12. The optical path indicated by the broken line indicates the optical path when there is no insertion plate PL). According to the law, the insertion of the light emitted from the point P1 Focused on the point A which plate PL passes, can be readily seen from the fact that condenses to the point A which pass the insert plate PL of the light emitted from the point P2.

  FIG. 13 shows an imaging apparatus 70 according to the seventh embodiment. Unlike the imaging devices 1, 20, 30, 40, 50, and 60 according to the first to sixth embodiments, the imaging device 70 includes two imaging lenses (a front imaging lens 42a and a rear imaging lens 42b) as an insertion plate. It is a type arranged before and after 3 respectively. The imaging device 70 includes, in place of the first housing C1 that houses the imaging lens 42 in the imaging device 50 according to the fifth embodiment, a first front housing C1a that houses the front imaging lens 42a, and a rear imaging lens 42b. The first rear case C1b and the first front case C1a and the first rear case C1b are arranged before and after the second case C2 containing the insertion plate 3, respectively. The three casings C1a, C2, C1b are coupled in this order by the casing coupling means J1, and the first rear casing C1b and the third casing C3 are coupled by the casing coupling means J2. An aperture stop S for adjusting the amount of light is provided at a position immediately after the insertion plate 3, and the insertion plate 3 in the second housing C2 is a plate rotation control provided outside the housing C. The rotation control around the optical axis AX can be performed from the apparatus 9. In such a configuration, since the insertion plate 3 can be disposed in the vicinity of the aperture stop S, the image quality can be further improved.

  The imaging devices 50, 60, and 70 according to the fifth to seventh embodiments are configured based on the imaging device 40 according to the fourth embodiment, but the imaging device 1 according to the first to third embodiments. Of course, it is also possible to configure based on. In addition, in the imaging devices 1, 20, and 30 according to the first to third embodiments, it is preferable that the insertion plate 3 can be rotated, as in the imaging device 40 according to the fourth embodiment. If an image is picked up while rotating the plate 3 at an appropriate speed, the light quantity distribution in the picked-up image can be made uniform, and a better image can be obtained. Further, since the symmetry of the defocused image (the shape of the blurred light beam) is improved with respect to images from different planes, this can be made inconspicuous. Furthermore, a higher quality image can be obtained by capturing the synchronization signal of the rotation period of the insertion plate 3 in the image processing device 6 and capturing the image in synchronization with the light reception of the imaging device 5.

As described so far, in the imaging optical system according to the present invention, a transparent parallel plate member is provided between the imaging surface 4 and one subject (the subject Q1 or the reference plane S1 of the parallel plate glass 8). By inserting an insertion plate (insertion plate 3 or insertion plate 33), a part of the light exiting from the subject and condensed on the imaging surface 4 passes through the insertion plate, An image of the subject and another subject image separated from the subject in the optical axis direction by a distance corresponding to the thickness and refractive index of the insertion plate (the subject Q2 or the reference surface S2 of the parallel plate glass 10). Can be imaged on the same image plane 4 at the same time. For this reason, according to the imaging optical system of the present invention, it is possible to simultaneously couple on the imaging surface without reducing the light amount (numerical aperture) and the resolution. In addition, according to the imaging devices 1, 20, 30, 40, 50, 60, and 70 according to the present invention, the image formed by the imaging optical system according to the present invention is captured. A high-quality image can be obtained. In the imaging optical system according to the above-described embodiment, a segment obtained by cutting the afocal optical system as the insertion plate 3 (or the insertion plate 33) into a semicircular shape, a sector shape, or the like in a plane perpendicular to the optical axis AX. By using it, it is possible to configure an imaging optical system that simultaneously forms an image of the subject arranged at a position separated in the optical axis direction on the imaging plane 4.
In contrast to the image of the subject Q1 on the pin and P on the surface, the image of the subject Q2 is caused by the light beam that has passed through the same segment of the insertion plate 3 as a defocused image. In order to shield this defocused light beam, a mask and a field lens in which a large number of fine pinholes are appropriately arranged over the entire focusing surface are inserted. The light flux that has passed through the mask and the field lens is taken in, and the mask surface is imaged and imaged by the subsequent re-imaging optical system. Also, by configuring various confocal systems or the like in which a microarray or the like is disposed in the vicinity of the focus surface, the defocused light beam can be similarly shielded and a clearer image can be obtained.

  Further, as shown in the third embodiment, the insertion plate is composed of a combination of a plurality of segments arranged in a circumferential direction around the optical axis AX, and the thickness of each of the plurality of segments. If the refractive indexes are different from each other, three or more subjects can be imaged simultaneously.

  Further, as shown in the fifth to seventh embodiments, the insertion plate 3 constituting the imaging optical system and one or a plurality of optical elements (such as the imaging lens 42 and the aperture stop S) other than the insertion plate 3 are mutually connected. If it is configured as a separable module and each module can be changed in arrangement with respect to the optical axis AX of the imaging devices 50, 60, 70, the module arrangement is recombined according to the use environment. By appropriately performing the above, it becomes possible to make the image pickup apparatus exhibit optimal optical characteristics, and there is an advantage that the usability is improved. Further, as described above, the image quality can be improved by providing the insertion plate 3 in the vicinity of the aperture stop S. However, if the insertion plate 3 and other optical elements are modularized, the insertion plate 3 And the arrangement relationship between the aperture stop S and the aperture stop S can be easily changed.

  So far, in the first to seventh embodiments, the object to be imaged by the imaging device has been described as a parallel plate glass in the above-described embodiment, but this is an example, and if it is a transparent parallel plate member, its material Need not necessarily be glass. In the above-described embodiment, the imaging optical system according to the present invention has been described as being incorporated in an imaging apparatus that captures an image formed by the imaging optical system using the imaging apparatus. The imaging optical system according to the above is not limited to the imaging device, but can be used by being incorporated in a projection lens or an observation device for observing an image formed on the imaging surface with a microscope or the like.

(Eighth embodiment)
In the first to seventh embodiments, the imaging optical system is an embodiment in which a parallel plate glass is inserted into the imaging optical system. However, in the eighth and subsequent embodiments, the lens is divided into a plurality of regions. , An embodiment of an imaging optical system in which each is shifted in the optical axis direction is shown.
First, the geometrical optical depth of focus and object depth of the object space and the optical system will be described with reference to FIGS. FIG. 14 illustrates the imaging relationship by the imaging lens L. FIG. Arrangement 1 shows the moving state of the image point when the object is close to the reference in-focus state. Arrangement 2 is a state in which the lens L is drawn out and focused on the moved object point, and the image plane is in the arrangement 1 state. At this time, the movement amount of the object point and the image point is shown in comparison with the state where the lens L is in the arrangement 1.

FIG. 15 shows the relationship of the geometric optical arrangement between the depth of focus of the imaging lens L and the subject depth. The relationship between the defocus amount on the image side and the object side and the minimum circle of confusion (image side resolution size) is displayed.
When the refractive index media in the image space are the same, the geometrical optical depth of focus and the subject depth of the optical system can be expressed by the focus position of the two conjugate points and the difference (blur amount). Relational expressions connecting two sets of conjugate points are well known. The optical specifications are as shown in FIG. The expression of the imaging relation with an arbitrary conjugate point as the origin is as shown in Expression (21).
βo / L′−1 / (βo L) = 1 / f ′ (21)
The focal length of the optical system is f ′, and the mutual distances (L, L ′) between the reference point and the focal point in image formation are expressed by equations (22) and (23) in the object space and the image space, respectively. However, the paraxial magnification of the reference origin is βo, and the paraxial magnification of the target focal point is β.
L = f ′ (1 / β−1 / βo) ≡ΔL (22)
L ′ = − f ′ (β−βo) ≡ΔL ′ (23)
When the principal point is the origin, βo = 1, and a well-known imaging equation is obtained.

However, if the paraxial magnification at the target reference focus position (o ₁ o ₁ ') is βo and the paraxial magnification at the defocus point (o ₂ o ₂ ') considering depth is β (23) The expression expresses the subject depth and the depth of focus on one side.
The focus process by the lens will be specifically described. Focusing on the defocused object point o ₂ is equivalent to moving the lens from the defocused image point o ₂ ′ to the focused image point o ₃ ′ by moving the lens by ΔX ₋ toward the object side. At this time, the defocused object point o ₂ becomes the focused object point o ₃ . Focusing is completed by such a process. However, the arrangement o ₄ o ₄ ′ translates the arrangement o ₁ o ₁ ′ by ΔX _{− at} both the lens and the conjugate point. As a result, the arrangement o ₄ o ₄ ′ has a defocus relationship with the arrangement o ₃ o ₃ ′. Equivalent reference arrangement for clarity.

Here, the movement relationship of the conjugate point with respect to the imaging lens arrangement is displayed in the reference arrangement o ₄ o ₄ ′ and the focus completion state (o ₃ o ₃ ′). Note that the defocus relationship in these states is that ΔL (o ₁ o ₂ ) is ΔL (o ₄ o ₃ ) = − ΔX + Δs, ΔL ′ (o ₁ ′ o ₂ ′) is ΔL ′ (o ₄ ′ o ₃ ′) = −ΔX. These relationships ΔL and ΔL ′ always satisfy the equation (24).
If the expression (21) is re-expressed as ΔL and ΔL ′ in the expressions (22) and (23), it can be expressed as the expression (24).
ΔL = ΔL ′ / [βo ² (1−ΔL ′ / βof ′)] (24)
On the other hand, the focal depth on one side at the image point formed by the lens is expressed as shown in equation (25).
ΔL '(±) = ± εFN (25)
Where ε is the minimum (allowable) diameter of the circle of confusion, and FN is the effective F number.
By substituting (25) into the equation (24), the one-side subject depth of focus (26) is obtained.
ΔL (±) = ± εFN / [βo ² ([1− (± εFN / βo f ′)] (26)

The reference (origin) of the equation (21) The focus magnification at the point where the magnification is focused is regarded as βo, and focusing at the position of the out-focus point is assumed, and the focus magnification at this point is regarded as β. Is expressed.
The depth of focus is expressed as equation (27) as the difference between the front focal depth and the rear focal depth in equation (25).
Δ ′ = ΔL ₊ ′ ₋ ΔL ₋ ′ = 2εFN (27)
The subject depth can be expressed as equation (28) as the difference between the front subject depth ΔL ₊ and the rear subject depth ΔL ₋ in equation (26) when | ΔL ′ / βof ′ | << 1 from equation (24).
Δ = ΔL ₊ -ΔL _- ≡2εFN / βo ² (28)
A high resolution lens, a large-aperture ratio lens, and a high-magnification lens require a deep subject depth. At first glance, it is difficult in principle to simultaneously obtain this requirement.

As can be understood from the equation (28), it can be understood that there is a considerable limitation. In the high-resolution optical system, the size ε of the allowable circle of confusion is small. A bright optical system has a small FN. As the photographing magnification βo by the optical system increases, its absolute value increases. An optical system with a long focal length f ′ with a constant shooting distance also has a large vertical magnification βo ² . Therefore, in any of these cases, the depth of subject becomes shallow in principle. In a single focus lens, focusing is achieved by extending the entire lens, and the effective F number of the lens is expressed by equation (29).
FN = Fo (1−βo / βp ² ) (29)
Fo is the F number at infinity, and βp is the pupil magnification of the imaging optical system. In an optical system of a finite distance arrangement, the effective F number has an important meaning as the F number. This is simply called the F number.

In general, the coordinate origin of the length is selected as the principal point in order to describe the lens specifications related to the imaging. The shooting distance of the lens (the distance from the object point to the image point) is called a conjugate length R (eg, o ₂ o ₂ ′, o ₃ o ₃ ′). The imaging magnification of the target conjugate point is β → βo and the origin H, H ′ (principal point) magnification is βo → β _H = 1, so the difference between the equations (23) and (22) and the principal point The sum of the intervals HH ′ is the conjugate length R ₀ = o ₁ o ₁ ′.
_{R 0 = L '+ HH'-} L = -f' (βo-β H) + HH'-f '(1 / βo-1 / β H)
= F '(1-βo) + HH' + f '(1-1 / βo) (30)
R = ΔL ′ + R ₀ −ΔL = −f ′ (β−βo) + R ₀ −f ′ (1 / β−1 / βo)
= F ′ (βo−β) + R ₀ + f ′ (1 / βo−1 / β)
= ΔL '+ L' + HH '-(L + ΔL) (31)
However, in FIG. 14, R = o ₂ o ₂ ′ here.
If the object-side and image-side numerical apertures are NA and NA ′, respectively, βo = nsin · θ / n′sinθ ′ when the sine condition is satisfied in the optical system, and | βo when the absolute value of βo is taken. There is a relationship of | = NA / NA ′. At this time, the numerical aperture on the object side and the numerical aperture on the image side are NA = n sin θ and NA ′ = n ′ sin θ ′, respectively.

The effective F number is expressed geometrically as FN = 1 / (2 tan θ ′). In the case of a bright optical system, conversion is generally made so that NA ′ = 1 / [(1+ (2FN) ² ) ^1/2 . Geometrical optics is as follows when NA ′ << 1.
FN = [(1 / (NA ′) ² −1) ^1/2 / 2≈1 / (2NA ′) (32)
Next, a lens used in the eighth embodiment will be described. In the present embodiment, one convex lens is cut into two parts along a line passing through the optical axis, and one divided part is shifted on the optical axis. FIG. 17 shows a lens dividing method used in the present embodiment, which is an imaging optical system using this two-divided combining element optical system. FIG. 17 shows the geometrical arrangement state and image formation relationship of the two-divided combining element optical system 110. This is an arrangement in which the components of the synthesis element optical system 110 composed of the segment element optical system divided into two parts are different from each other and the segment element optical systems A ₀ and A ₁ having a semicircular shape are synthesized.

The structure of the synthesizing element optical system 110 and the bisecting azimuth angle (Φ ₀ , Φ ₁ ) and the image formation relationship are associated with FIG. FIG. 17A shows a front view seen from the optical axis direction, and FIG. 17B shows a side view seen from the direction perpendicular to the optical axis.
The synthesizing element optical system 110 divides a lens having positive refractive power convex on both sides into two sections (radial angle division cutting radially) into fragment element optical systems A ₀ and A ₁ around the optical axis in a cross section including the optical axis. ). The fragment element optical systems A ₀ and A ₁ are arranged so as to be shifted by a specific amount D on the optical axis as shown in FIG. Fragment element optical systems A ₀ and A ₁ capture a semicircular incident light beam centered on the optical axis in the radial cross section, and the fragment element optical systems do not overlap each other in the cross section perpendicular to the optical axis. Has been placed.

It is possible to construct a coaxial optical system by recombining element optical systems composed of pieces of a plurality of optical systems cut and divided with the optical axis as the central axis. Furthermore, in an optical system having a potential function capable of coaxial imaging, each directional fragment part of the fragment element optical system described above is arranged freely along the optical axis, and imaged by each fragment element optical system. An optical system including a possible optical system is configured.
It is optimal that these piece element optical systems have the same refractive power, but they may have different refractive powers. Further, the photographing magnification of each piece element optical system may be changed according to the photographing distance. In this embodiment, an example of a biconvex lens is shown, but the lens is not limited to this, and a biconcave lens, a planoconvex lens, a planoconcave lens, a cemented lens, or the like may be used.

FIG. 18 shows an embodiment in which the lens is divided into four. FIG. 18A is a front view, and FIG. 18B is a side view, showing an imaging relationship with the corresponding conjugate point (0, 0 ′). The lens is divided into four, the central angle of the sector is 90 °, and the fragment element optical systems A ₂ , A ₃ , A ₄ , A ₅ are arranged shifted on the optical axis. The lens thickness is D, the position of A ₂ is used as a reference, and the fragment element optical systems A ₃ , A ₄ , and A ₅ are arranged on the optical axis while being shifted by −D, −2D, and −3D, respectively.
The number of divisions and the distance by which the fragmentary element optical system is moved can be optimized according to the resolution and purpose, and depending on the depth range to be covered and the amount of light to be captured. The divided wavefront by the fragment element optical system does not necessarily need to cover the entire light beam cross section of the imaging optical system.
Multiple fragmentary element optical systems move along the optical axis in order to keep the image plane by the optical system constant, corresponding to multiple subjects located at different positions along the optical axis and their positional differences To do. A plurality of these fragment element optical systems are arranged between the subject and the imaging surface, and at the same time, without overlapping each azimuth portion with the optical axis in the cross section of the light beam as the central axis.

For this reason, it is possible to configure an optical system capable of simultaneously imaging a plurality of subjects arranged at different positions along the optical axis. Each element optical system in the focus arrangement state of each of the above-described fragment element optical systems focused on a plurality of subject positions is a combination element optical system in which so-called fragment portions are combined and arranged. In either case, a finite distance imaging system can be easily configured.

This synthesizing element optical system may be composed of non-afocal optical element fragments composed of optical systems having the same focal length and having an arbitrary cross section. These fragment element optical systems (optical element fragments) are coaxial optical systems that are radially equiangularly divided with respect to the optical axis. Partial cutouts are created equally, and these fragment element optical systems are shifted to an arrangement corresponding to the focus arrangement of each object surface while shifting the direction without overlapping these fragments, thereby forming a composite joint configuration. In this way, a composite optical element composed of optical element pieces having the same focal length can be easily manufactured. In this way, multiple focusing can be performed simultaneously, and the super subject depth range can be further expanded.

In order to fix the thick transparent subject along the optical axis and the image plane corresponding to the position difference of each cross section of the subject object, the plurality of fragment element optical systems move in focus along the optical axis, and the subject A plurality of fragmentary element optical systems at the same time are placed in each azimuth portion with the optical axis in the light beam cross section of the imaging optical system as the central axis, and multiple subjects placed at different positions are imaged simultaneously. It is easy to do.

In order to make the image plane corresponding to the positional difference between the subject and each cross section of the object along the optical axis the same position, the multiple fragment element optical systems move in focus along the optical axis to capture the subject and the image. A plurality of fragmentary element optical systems are arranged between each surface and each azimuth portion with the optical axis in the light beam cross section of the imaging optical system as the central axis. Furthermore, in order to prevent deterioration of the imaging performance due to this in-focus movement, the lens interval of the lens components of these fragment element optical systems is changed mutually, and the aberration variation of each fragment element optical system is suppressed, thereby reducing the reference It is possible to ensure a certain degree of imaging performance in the arrangement.

In this way, it is possible to simultaneously image a plurality of subjects arranged at different positions with good image quality. However, it is necessary to avoid a great change in refractive power due to a change in the interval between lens components.
Since the depth range is thus expanded, various aberrations are generated by the combining element optical system. Therefore, this combining element optical system is constituted by a plurality of lens components, aspherical surfaces, etc., and can correct these aberrations. In particular, it is necessary to correct chromatic aberration, spherical aberration, field curvature, coma aberration, and distortion. In addition, when priority is placed on imaging performance, the range of the super-subject depth should not be made too wide, and measures such as setting the magnification (paraxial lateral magnification) of the combining optical element appropriately close to the same magnification can be used. it can.

Note that when realizing an ultra-deep optical system, it is inconvenient that the magnification at which each subject is imaged changes. This is because the size of the image slightly changes and overlaps in each in-focus state, so that it is not suitable for judging a fine structure such as an outline and a shape. In general, when a subject at a different position is imaged by an optical system having refractive power, the imaging magnification changes. The inconvenience caused by this magnification change can be solved by image processing or the like.

(Ninth embodiment)
Next, an embodiment of an afocal optical system will be described.
To consider an optical system in which a cross section including the optical axis of an afocal optical system or a telecentric optical system is angularly divided and cut radially around the optical axis, and these cut optical elements are rearranged along the optical axis. To. An element optical system having a cross section including the optical axis and including a plurality of optical system fragments obtained by cutting and dividing the optical system with the optical axis as a central axis is synthesized. At this time, the entire assembly of the fragmentary element optical systems can constitute a coaxial optical system and has a potential function capable of constituting an afocal optical system capable of coaxial imaging. Each directional fragment portion of the fragment element optical system described above is arranged freely along the optical axis.

In addition, a combining element optical system is configured which includes a plurality of subjects arranged at different positions along the optical axis and each part of the fragment element optical system corresponding to the position difference and simultaneously focused on each position. This synthesis element optical system constitutes an afocal optical system or a telecentric optical system. Between the subject and the imaging surface, each part of the above-mentioned fragment element optical system of the combining element optical system is in the optical axis direction and the radial direction in each azimuth part in the cross section of the incident light beam with respect to the optical axis of the imaging optical system. Are appropriately arranged and synthesized.

For this reason, an optical system capable of simultaneously imaging a plurality of subjects arranged at different positions can be configured. For this purpose, the optimum optical system is an afocal optical system (telescope system). One of the advantages of the present invention is that the afocal optical system is focused by the entire movement and the paraxial lateral magnification is unchanged. That is, regardless of the distance at which this combining element optical system A forms an image, the paraxial lateral magnification is always the pupil magnification (reciprocal of the telescope magnification) of this optical system. In order to ensure ultra-deep, a practical ultra-deep optical system can be realized by adopting this type optical system and constructing a simultaneous multi-polymerization focal state.

First, the imaging relationship of the afocal optical system will be described. FIG. 16 illustrates the image formation relationship by the afocal optical system. Arrangement 1 shows the moving state of the image point when the object point approaches the reference in-focus state. Arrangement 2 is a state in which the lens L is drawn out and focused on the moved object point, and the image plane is in the arrangement 1 state. At this time, the movement amount of the object point and the image point is shown in comparison with the state in which the lens is disposed.

As shown in FIG. 16, the afocal optical system has almost the same imaging relationship as that of the normal optical system shown in FIG. The total refractive power of the afocal optical system is 1 / f _A ′ = 0. In the case of a total of two groups, the focal length of the first lens group is f ₁ ′, the focal length of the second lens group is f ₂ ′, and the principal point interval is d. Assume that the refractive index of the medium is the same in the object space and the image space. Each relationship is as follows.
1 / f _A '= 1 / f ₁ ' + 1 / f ₂ '-1 / (f ₁ ' f ₂ ') = 0
Thus, d = f ₁ '+ f ₂ '.

As is clear from these equations and equation (21), the paraxial angular magnification γ _PA ′ is expressed as follows. The parallel light beam incident from the off-axis at an angle u is refracted by the optical system and exits off-axis as a parallel light beam at an angle u ′. At this time, one light beam intersecting with the optical axis is represented, and the intersection points P and P ′ are conjugate points in the object space and the image space by this optical system. Pay attention to the relationship between the conjugate points.
γ _PA = u ′ / u = −f ₁ ′ / f ₂ ′ and γ _PA = 1 / β _PA .
With this conjugate point as the origin, the distance between the object and the image is measured as S and S ′, respectively. The imaging equation of the synthetic optical system constituting the telescope system is expressed as follows. However, the length code defines the length as-and + in the left-right direction from the reference point, respectively. In the afocal optical system, the equation (21) is as follows.
β _PA / S′−1 / (β _PA S) = 1 / fA ′ = 0
S ′ = β _PA ² S (33)
This indicates the paraxial longitudinal magnification α _PA = S ′ / S and α _PA = β _PA ² of the telescope system. In general, the paraxial longitudinal magnification α, the paraxial angular magnification γ, and the paraxial lateral magnification β have a relationship of β / γ = α with each other at the conjugate point.

In an arbitrary finite distance arrangement, the paraxial vertical magnification α _P ′, which is the ratio of the object point distance S and the image point distance S ′, is always constant. Therefore, the paraxial lateral magnification β _P ′ is also constant.
β _PA ² = S '/ S
β _PA = −f ₂ ′ / f ₁ ′ = 1 / γ _PA (34)
Since the refractive power of the afocal optical system is 1 / f _A ′ = 0, if the lateral magnification of each lens group of the afocal optical system in this finite distance arrangement is β ₁ ′ and β ₂ ′, respectively, The relationship is established.
1 / f _A '= 1 / (β ₂ ' f ₁ ') + β ₁ / f ₂ ' = 0
Therefore, β _PA = β ₁ β ₂ = −f ₂ ′ / f ₁ ′ is satisfied.
Consider the depth in a finite distance imaging arrangement of an afocal optical system. It is assumed that the afocal optical system is spatially fixed and the object point is moved from the photographing reference point of the afocal optical system by ΔS during photographing. At this time, when the image point is also moved by ΔS ′ from the position of the reference image point, the relationship between S and S ′ is similarly as follows.

That is, in the afocal optical system, the expression (24) is expressed as follows.
ΔS = ΔS '/ β _PA ²
S + ΔS = (S ′ + ΔS ′) / β _PA ² (36)
However, S and S ′ are always measured using the conjugate point as the origin. The one-side depth of focus at the image point formed by the afocal lens is expressed by equation (37) from (25).
ΔS ′ ± = ± ε _A / 2NA ′ (37)
Where ε _A is the minimum (allowable) circle of confusion circle and a numerical aperture NA _A ′ on the image side by the afocal optical system. By substituting (37) into the equation (36), the one-side subject depth of focus (38) is obtained.
ΔS (±) = ± ε _A / (2NA _A 'β _PA ² ) (38)
In equation (36), the reference (origin) magnification and the focus magnification at the point of interest are all β _PA .
Even if the out-of-focus point is in focus, the focus magnification is β _PA . The depth of focus is expressed as equation (39) as the difference between the front focal depth and the rear focal depth in equation (37).
ΔA ′ = ΔS ₊ ′ ₋ ΔS ₋ ′ = ε _A / NA _A ′ (39)

The subject depth can be expressed as the equation (40) of the difference between the front subject depth ΔS ₊ and the rear subject depth ΔS _{− in} the equation (38).
ΔA = ΔS ₊ −ΔS ₋ ≈ε _A / (NA _A 'β _PA ² ) (40)
Since the afocal optical system has no refracting power as shown in equation (33), the relationship (36) of the defocus amount is very simple and easy to handle theoretically. The handling of these synthetic optical systems is equally simple.

On the other hand, in order to cancel the image point movement amount ΔS ′ by the movement ΔX of the afocal optical system, the relationship as shown in the equation (41) is obtained. In the arrangement 2 of FIG. 16, ΔS ′ = − ΔX and ΔS = Δs−ΔX, and the amount of deviation Δs of the object point from the reference point is as follows from the equation (36). As a result, the image plane can be fixed.
Δs = ΔX (1-1 / β _PA ² ) (41)
Equation (41) shows that when the reference lens moves to the object side by ΔX (−), the in-focus object point is shifted by Δs (+) and further closer to the lens side. Even when the lens is moved when β _PA = ± 1, neither the object point nor the image point moves.

Therefore, in order to move the lens, fix the image point, and change the position of the imaged object point, an appropriate paraxial lateral magnification value (1 / β _PA ² <1) is required. The paraxial angle magnification γ _PA = 1 / β _PA is equal to the telescope magnification. If γ _PA is increased, a large focus shift Δs (−) can be obtained. If a plurality of optical systems are respectively arranged corresponding to these shifted object points and focused at the same time, it becomes possible to focus at a large distance at the same time. The plurality of optical systems are combined with a fragmentary element optical system as in the present invention. As a result, multiple focus can be realized, and the subject depth can be greatly increased.

In a large aperture ratio lens, when a deep subject depth is required, there is a considerable limitation as can be understood from the equation (40). For example, when ε _{A is} constant, a bright optical system has a large NA _A, but it is desirable to ensure the subject depth. The object point shift amount | Δs | increases when the imaging magnification β _PA of the afocal optical system is smaller than the fixed movement amount ΔX of the afocal lens. Therefore, the depth can be substantially increased by the focus.
Under certain conditions, a high-resolution optical system has a small allowable circle of confusion circle ε _A. Since the depth of field ΔS is shallow, to increase the Delta] s, or is beta _PA reduced, the moving amount | can be understood that it is sufficient to increase the value | [Delta] X. By combining and arranging the fragment element optical systems in this manner, it is possible to easily satisfy | Δs | ≧ | ΔS |.

When considering these synthetic optical systems, in order to analyze the imaging process in an easy-to-understand manner, the optical images are always displayed in FIG. Yes. However, though symbolic, the generality of the imaging relationship has never been lost.

Next, the optical system of this embodiment using an afocal optical system will be described. 19 and 21 show a front focus type optical system configuration. In this optical system, the combining element optical system 110 or 111 (afocal optical system) shown in the eighth embodiment is mounted in front of the imaging optical system L.
The combination magnification βc in the reference arrangement is expressed by the equation (42) and is as follows.
βc = β _PA βo (42)
When the focal length of the imaging optical system is f ′, the depth equation is expressed as follows.
ΔL = ΔL ′ / [βo ² (1−ΔL ′ / βof ′)]
ΔS ′ = ΔL (43)
ΔS _AM = ΔS ′ / β _PA ² = ΔL ′ / [β _PA ² βo ² (1−ΔL ′ / βof ′)]
ΔS _AM (±) = ± εFN ′ / [β _PA ² βo ² ([1− (± εFN ′ / βo f ′)] (44)
The movement of the object point of the imaging optical system and the movement amount of the image point of the afocal optical system are equal to each other as shown in Equation (43). When combining optical system on the image side _{NA AM '≒ 1 / (2FN} '), include synthetic magnification equation (42), one side depth of field [Delta] S _AM object point of reference arrangement is expressed as (44).

(25) 'in consideration of the focal depth delta _AM synthesis system' FN synthesis system F-number from the equation is expressed as equation (45) as the difference between the rear focal depth and the front focal depth (45) below.
Δ _AM '= ΔL +'-ΔL _- '= 2εFN' (45)
Depth of field delta _AM synthesis system is expressed as follows in a similar manner.
_{Δ AM = ΔS AM + -ΔS AM} - ≒ 2εFN '/ (β PA 2 βo 2) (46)
However, when | ΔL ′ / βof ′ | << 1, the approximation of (46) holds. On the other hand, when the approximation is not established, the equation (44) is directly used.

Further, the composite system F number FN ′ is limited by the imaging optical system when the image side NA _A ′ of the afocal optical system is larger than the object side NA of the imaging optical system. However, when the afocal optical system is a dark optical system, the brightness of the composite optical system becomes the composite F number FN ′ limited by the afocal optical system.
When NA _A ′ ≧ NA, FN ′ = FN (47)
When NA _A '<NA, FN'> FN (48)
In combining optical system of the front focus type, equation (41) _{as, | Δs |> | ΔS AM} | and it is easily possible to. By configuring these combining optical systems with a plurality of fragmentary element optical systems as in the present invention, multiple focus can be realized and deep subject depth can be gained.

As can be understood from FIG. 19 and FIG. 21 as the characteristics of the front type, even if the object point moves at the magnification β _PA that bears the front converter section (synthetic element optical system A) and is defocused, it remains unchanged. However, the object point of the imaging lens moves. In order to cancel this, it is possible to focus on different object points at the same time by fixing the focus surface of the composite lens system by refocusing with the partial movement of the divided converter lens consisting of the fragment element optical system. is there.
In particular, in order to efficiently secure the depth of field, it is better that the imaging optical system L is βo ² <1, and the combining element optical system A is β _PA ² <1. In general, when an optical system defocuses an object point deviated from a specific focal point, there is a perspective deformation of the image in addition to image blurring. These are fundamental phenomena. By installing an afocal optical system, it is possible to alleviate the disadvantages caused by defocusing, and it is possible to realize a super subject depth (multiple focus).

In FIG. 21 of the front type, a composite optical system composed of a plurality of Afall optical system fragment elements is mounted in front of the imaging optical system. It corresponds to the integer i in a discrete manner, and the fragment element optical system is moved by focusing while fixing the image plane focus plane of the i-th subject to the same plane, so that subjects at different positions i-th can be imaged simultaneously. it can.
On the reference focus plane, i = 0, Δs ₀ = 0, ΔS ₀ = 0, ΔX ₀ = 0, Δs _i = ΔX _i (1-1 / β _PA ² ), and ΔS _i = Δs _i .
In the combining optical system constituting the front type, the combining magnification does not change even when simultaneously focusing on different subject position cross sections in the depth direction along the optical axis.

(10th Embodiment)
Although the front focus type has been described in the ninth embodiment, rear focus is described in the tenth embodiment.

Assume that the combining element optical system 110 or 111 is mounted behind the imaging optical system L shown in FIG. 20 or FIG. This is a configuration of a rear focus optical system. In the standard arrangement, the synthesis magnification β _C is similarly β _C = βoβ _PA . The composite F number FN ′ of the composite optical system is always limited by the brightness NA _A of the afocal optical system.
When NA ′ <NA _A , FN ′ = β _PA FN ≧ 1 / (2NA _A ′) (49)
When NA '≧ NA _PA , FN' ≒ 1 / (2NA _A ') (50)
The focal depth of the synthesis system is expressed as the image plane movement of the afocal optical system as follows.
ΔS ′ (±) = ± εFN ′ (51)
The defocus relationship by the afocal optical system is expressed as follows.
ΔS = ΔS '/ β _PA ² (52)

The image plane movement amount ΔL _AM ′ of the imaging optical system is equal to the image object plane movement amount ΔS of the afocal optical system.
ΔL _AM '= ΔS (53)
Transmit the defocus amount [Delta] S 'of the afocal optical system in the imaging optical system, the relationship between the defocus amount [Delta] L _AM synthetic optical system is represented as follows.
ΔL _AM = ΔL _AM '/ [βo ² (1-ΔL _AM ' / βof ')] (54)
ΔL _AM = ΔS ′ / [β _PA ² βo ² [1-ΔS ′ / (β _PA ² βof ′)]] (55)
ΔS '→ ΔS' the (±) as _{ΔL AM → ΔL AM (±)} .
ΔL _AM (±) = ± εFN ′ / [β _PA ² βo ² [1- (± εFN ′) / (β _PA ² βof ′)]] (56)
When the defocus amount is small, the subject depth of the combining optical system is similarly expressed by equation (57).
_{Δ AM = ΔL AM + -ΔL AM-} ≒ 2εFN '/ (βo 2 β PA 2) (57)
However, when the image plane movement amount ΔS ′ is large, the approximation of the expression (57) may not be established depending on the combination magnification and the magnification of the afocal optical system. In this case, it is necessary to directly use equation (57).

Similarly to the case where the afocal optical system is mounted on the front side of the imaging optical system, the expression (41) is established even if the afocal optical system is mounted on the rear side. This corresponds to returning (focusing) the image plane to the original reference image plane by moving (focusing) the arrangement of the afocal optical system when the image plane is defocused by ΔS ′. At this time, the object point of the acoustic optical system has moved by Δs from the reference arrangement. This is the image plane trajectory movement amount ΔL ′ = Δs of the imaging optical system mounted in front of the afocal optical system.
Δs = ΔX (1-1 / β _PA ² )
The movement amount ΔL of the object point in this arrangement is related by the equation (24) or (54).

In this way, it is possible to appropriately satisfy | Δs | ≧ | ΔL _AM '| with respect to the defocus of the subject. Further, by doing so, the combining optical system is focused on an object located at a position separated by ΔL from the reference object point. As shown in FIGS. 21 and 22, a multi-focus optical system can be realized by simultaneously arranging a plurality of fragment elements of the afocal optical system having different movement amounts ΔX around the optical axis.
ΔX → ΔX _i , ΔL → ΔL _i (i = 0, ± 1, ± 2,..., ± N)
This makes it possible to configure a super subject depth optical system.
In the synthesizing optical system constituting the rear type, the imaging magnification βo → βo that the imaging optical system L (in the case of a non-afocal system) bears when simultaneously focusing on different subject position cross sections in the depth direction along the optical axis _{Since i} changes, the composite magnification β _C → β _ci also changes.

This is because, in the present invention that aims at super-subject depth at the same time with multiple focus, additional processing such as magnification correction and separation of multiple images may be required depending on the purpose. In order to ensure the depth of field efficiently, when the imaging optical system L is βo ² <1, the combining element optical system A is preferably β _PA ² <1.

In order to simultaneously observe and inspect the surface of an arbitrary subject and a plurality of cross sections before and after the subject, a plurality of fragmentary element optical systems with appropriate division angles as shown in FIG. 18 are mounted between the subject and the imaging optical system. At this time, in the arrangement as shown in FIGS. 19 and 20, a plurality of fragment element optical systems as shown in FIG. 18 are made to coincide with the optical axis at the same center as the optical axis of the imaging optical system L.

A composite element optical system 110 or 111, in which a plurality of (segment) pieces of segmented element optical systems with appropriate focusing are fixed and synthesized, is arranged rotationally symmetrically with respect to the optical axis. For this reason, the position where the subject is imaged moves and is focused on a plurality of different cross sections along the optical axis, and the image is further formed by the imaging lens L.

The structure of the synthesis element optical system 111 for realizing this will be described in detail. A combining element optical system 111 as shown in FIG. 19 is mounted on the imaging lens L to constitute a combining optical system. As shown in FIGS. 19 and 21, the front type is arranged in front of the imaging lens L, and is divided into four parts around the optical axis. These are composed of parts of the fragmentary element optical system having different orientations with respect to the optical axis and different in-focus arrangements.

Usually, each of these sectional element optical systems forms a fan-shaped effective light beam section and is mounted and arranged. By making such a sectional element optical system rotationally symmetrical about the optical axis, light beams emitted from four cross sections with different depth directions of the subject are divided into four wavefronts. Each wavefront light flux is just focused on the same focus plane by the imaging lens.
As a result, these multiple images can be taken simultaneously. By further dividing the cross-section element optical system, it is possible to simultaneously focus on a large number of force cross sections, and simultaneously image deeper areas.

In the rear type shown in FIG. 22, a composite optical system including a plurality of fall optical system fragment elements is mounted behind the imaging optical system. Discretely corresponds to the integer i, and the image plane focusing plane of the i-th subject is fixed to the same plane, the fragmentary element optical system is moved in focus, and the subjects at different positions i are simultaneously imaged. Can do.
At the reference focus plane, i = 0, Δs ₀ = 0, ΔS ₀ = 0, ΔX ₀ = 0, Δs _i = ΔX _i (1-1 / β _PA ² ), ΔL _i ′ = Δs _i , ΔL _i ′ is ΔL _i .
In the synthesizing optical system constituting the rear type, the focus magnification of the imaging optical system L (when non-afocal system) changes when simultaneously focusing on different subject position sections in the depth direction along the optical axis. The composite magnification changes.
This may require additional processing such as image processing for the front type in the present invention aiming at super-subject depth. Note that this is not the case when the imaging optical system L is an acoustic optical system.

(Eleventh embodiment)
The present embodiment is an embodiment that employs a Galileo telescope type optical system.
Based on the above theoretical considerations, using the features of the front type and rear type, the fragment element optical system sets an appropriate magnification (γ _PA = 1 / β _PA ). For example, as shown in FIG. 25, the size reduction can be easily achieved by adopting the Galileo telescope type.

Setting a magnification close to the same magnification deteriorates the focusing efficiency, but it is easy to ensure imaging performance. On the other hand, if the telescope magnification (paraxial angle magnification γ _PA ) is increased, the lens diameter on the object side must be increased in order to secure the field angle (field of view). On the other hand, if it is arranged in the reverse Galileo type, it tends to be a reduction telescope magnification, but it is easy to secure a wide angle of view and a deep depth.

In addition, a plurality of these piece element optical systems may be employed that are equiangularly divided radially with respect to the optical axis and are configured from exactly the same part. As a result, the fragment element optical system can be used in common, and a synthesis system can be constructed at a low cost. By such a combining element optical system, multiple focusing can be performed at the same time, and the range of the super subject depth can be further expanded. Since the combining element optical system focuses on a wide range, various aberrations occur. In order to correct this, it is possible to cope by correcting the interval of the constituent lens components. This makes it possible to secure imaging performance easily and inexpensively by using parts of a common fragment element optical system.

In the front type, from FIG. 19 and FIG. 25, the Galileo characteristic is that the angular magnification is γ _1PA = 1 / β _PA > 0 and f ₁ 'f ₂ '<0, and a virtual image is formed. Since it is connected at the image side focal point F ₁ ′ of the first lens (f ₁ ′> 0) and the object side focal point F _{2 of} the second lens (f ₁ ′ <0), it is spatially advantageous. An image for an object point existing outside the lens exists inside the lens. For this reason, if the optical system connected to the rear side is arranged, the total length of the synthesis optical system can be shortened.
Since β _PA = β ₁ β ₂ > 0, the magnifications of the respective lens groups are always the same as β ₁ and β ₂ . Here, each lens group has an image formed by a combination of a real image and a virtual image (imaginary point). This type is suitable for constructing a compact and relatively bright optical system with a relatively small field of view. On the other hand, in the rear type, from FIG. 20 and FIG. 25, the reverse Galileo type is suitable to form an imaginary object point and a real image by reversing the front and back of the Galileo lens.

(Twelfth embodiment)
This embodiment is an embodiment that employs an inverted Galileo telescope type optical system.
In the front type, as shown in FIGS. 19 and 26, the inverse Galileo is characterized by an angular magnification of γ _PA = 1 / β _PA > 0 and f ₁ 'f ₂ '<0, and forms a virtual image. Since it is connected at the image side focal point F ₁ ′ of the first lens (f ₁ ′ <0) and the object side focal point F _{2 of} the second lens (f ₂ ′> 0), it is spatially advantageous. An image point corresponding to an object point existing outside the lens exists inside the lens. Therefore, if the optical system connected to the rear side is arranged, the total length of the synthesis optical system can be shortened.
Since β _PA = β ₁ β ₂ > 0, the magnifications of the respective lens groups are always the same as β ₁ and β ₂ . Here, the image formation which each lens group bears is composed of a combination of a virtual image and a virtual image. This type has a relatively wide field of view and is suitable for constructing a compact and relatively dark optical system.

On the other hand, in the rear type, from FIG. 20 and FIG. 26, an image in which the front and rear of the inverted Galileo lens are reversed and the Galileo type constitutes a imaginary point and a real image is suitable. Galileo type and reverse Galileo type are not only reversed in front and back, but in each optical system type, the magnification β ₁ , β ₂ that each lens group bears can be a combination of negative, positive and positive It can be understood that it is configurable.
ΔS = ΔS ′ / β _PA ²
1 / fA ′ = 1 / (β ₂ f ₁ ′) + β ₁ / f ₂ ′ = 0
β _PA = β ₁ β ₂ = −f ₂ '/ f ₁ '

As shown in FIG. 24, the Kepler telescope system has a feature that the angular magnification is γ _PA = 1 / β _PA <0, and a real image is formed here. Since the image side focal point F ₁ ′ of the first lens (f ₁ ′> 0) and the object side focal point F _{2 of} the second lens (f ₂ ′> 0) are connected, before and after the other optical system. When this optical system is connected and arranged, the total length of the synthesis optical system becomes very long. In general, it is difficult to make it compact. Since β _PA = β ₁ β ₂ <0, the magnifications of the respective lens groups have different signs of β ₁ and β ₂ . Here, each of the lens groups forms an image formed by a combination of a real image and a virtual image. In particular, in order to secure a wide angle of view at a high magnification as the mounting synthetic element optical system in the present invention, it is functionally desirable to configure a double-sided telecentric optical system (Kepler type).

As a result, it is possible to change the focus area while maintaining a constant paraxial magnification of each fragment portion with a suitable size and length of the optical system. However, as can be seen from the combining optical system in FIG. 23, the system size inevitably increases in a system with a large screen size and subject size.

In general, any telescope optical system (afocal optical system) adopted as a fragmentary element optical system has a magnification even if the object whose specific height is moving along the optical axis is in focus. Since it is invariant, you will always see an image of the same height. This feature is therefore very useful. On the other hand, this piece element optical system may be an object side telecentric optical system.

(13th Embodiment)
As a thirteenth embodiment, an embodiment in which a non-telecentric optical system is adopted as an imaging lens will be described. This embodiment is characterized in that the synthetic optical element 110 or 111 is rotated around the optical axis.

When a non-telecentric optical system is employed for the imaging lens L and an afocal optical system or a telecentric optical system is employed for the fragment element optical system, there are disadvantageous problems. For example, when a two-sided telecentric optical system is considered as a fragment element optical system, as shown in FIG. 16, the surfaces corresponding to the front surface (o ₃ ) and the back surface (o ₁ ) of the transparent subject having a thickness in the optical axis direction are simultaneously inspected. Suppose it is implemented. Between the transparent subject and the imaging lens L, a two-segment segmented element optical system A having an effective aperture cross section on each of the upper and lower half sides as shown in FIG. At this time, the fragment element optical system moves in focus, moves to the front and back of the subject on the optical axis, is focused on two different cross sections along the optical axis, and the image plane of the fragment element optical system is always fixed. The

In the in-focus arrangement of FIG. 16, the center of the chords of the effective apertures of the half-circle divided fragment element optical systems A ₀ and A ₁ of FIG. Match. A light beam passes through each of the upper and lower semicircular effective aperture portions with respect to the optical axis, passes through the two combining element optical systems 110 arranged in focus, and is simultaneously captured as a light beam incident on the imaging lens system L. Arranged as possible.

However, the light beam emitted from the upper half of the optical axis of the subject forms only an image focused on the subject surface. On the other hand, it can be seen from FIGS. 16 and 17 that the luminous flux emitted from the lower half of the optical axis of the subject forms only an image focused on the back surface of the subject, corresponding to the characteristics of the imaging lens L in FIG. . The image formed by the imaging lens is an image in which the lower half of the optical axis is the upper half of the subject. Similarly, the upper half area of the subject is an image of the lower half portion from the optical axis. For this reason, there is a problem that an off-axis subject object cannot be focused in the same field of view at the same time.

If the fragment element optical system is mounted and arranged in an annular lens barrel so as to be rotationally symmetric, it can be regarded as a converter. The optical axis and the center of the chord of the effective aperture of the semicircular piece element optical system are matched, and this converter is rotated around the optical axis.
The light beams emitted from different cross-sections of the subject in the depth direction are divided into wavefronts, and the two optical images that are just focused on the same focus surface are divided into two at the center of the image plane by this mechanical rotation. Images can be alternately formed vertically. As a result, different position cross sections of the subject can be simultaneously imaged over the entire visual field region on the image plane.

Furthermore, as shown in FIG. 18, each segment of the synthesized sector-shaped fragmentary element optical system becomes dark as the effective aperture decreases. Further, the passing oblique light beam is partially blocked at the side surface of the boundary of each segment. In order to alleviate this effect, the synthetic fan-shaped fragment element optical system of FIG. 18 is inserted and arranged in an annular lens barrel frame so as to coincide with the ridge including the vertex of the synthetic fan-shaped fragment element optical system. A synthetic element optical system having a synthetic sector cross section about the axis is rotated. As a result, the light quantity distribution in the imaging screen can be made uniform with respect to the optical axis.

In addition, the mountable combining element optical system can be disposed on the front side (object space), inside, or rear side (image space) with respect to the imaging optical system. If it is arranged on the front side as shown in FIG. 19, it is desirable that it is as close as possible to the imaging optical system while satisfying the imaging relationship. As shown in FIG. 20, when it is arranged on the rear side, it is desirable that the imaging optical system be as close as possible. As a result, the optical system can be easily reduced in size.

When the imaging optical system is used in an enlargement system, it is more effective to arrange it in the object space in consideration of the efficiency of depth. On the other hand, considering the load of brightness, it is more effective to arrange in the image space. In particular, when it is disposed inside the imaging optical system, it is desirable that the vicinity of the aperture stop be satisfied while satisfying the imaging relationship. Furthermore, a symmetrical parallel system that is arranged before and after the stop is preferable. This is because both the on-axis light beam and the off-axis light beam can be divided and controlled more evenly at the same time.

When simultaneously imaging subjects arranged at different positions, the composite imaging magnification cannot be made constant in arrangements other than the front type. However, an ultra-deep optical system having a substantially constant combined imaging magnification can be configured by using an imaging optical system as a telecentric optical system or an afocal optical system.

In the present embodiment, a plurality of subjects arranged at different positions are arranged between the subject and the imaging image plane in order to make the light amount distribution in the imaging screen uniform and shape the light flux shape of the imaging blur of the defocused image. In order to be able to capture the entire field of view at the same time, we introduced a rotation mechanism that rotates the combined element optical system consisting of each part of the optical axis of the imaging optical system. Yes.

The rotating mechanism is equipped with, for example, an annular (drum) motor DM, which is a lens barrel containing the composite element optics. This makes it possible to rotationally drive the synthesizing element optical system while realizing a reduction in size. In addition, it can be realized as an external drive by a gear chain mechanism.

By applying an appropriate rotation speed to the combining element optical system, even when an imaging optical system capable of simultaneously imaging only a part of the visual field is adopted, apparently simultaneous imaging is possible in the entire visual field region. Furthermore, by capturing and adopting the synchronization signal of this rotation period in the image processing system, it is possible to capture the video signal purposely by scanning the cross section of the subject and taking an image with the light receiving element of the camera C. As a result, desired image processing such as screen composition and video processing is possible.

As can be seen from FIGS. 17 and 9, when an afocal optical system or a telecentric combining element optical system is used, the light field used for imaging is limited, so the field of view to be imaged is limited. Therefore, the incident light beam in FIG. 17 is changed by the rotation of the combining element optical system, and the region in the cross section of the subject is scanned.
Furthermore, the shielding of the passing light beam at each fragment boundary surface of the combining optical element can be relaxed by rotation. In this way, when the imaging optical system is a non-telecentric optical system and the combining optical element has telecentricity, simultaneous multiple focusing is performed. Therefore, it is very effective to rotate the combining optical element for the same reason.

Furthermore, by rotating the combining element optical system, the symmetry of the defocused image (the shape of the blurred light beam) is improved with respect to images from different object cross sections, and it can be made inconspicuous. Furthermore, the non-uniformity in the amount of light generated due to the split shape of the light beam cross section can be made uniform in the imaging screen.
Further, as a modification, it may be arranged between the subject and the captured image plane, the fragment element optical system is composed of a plurality of lens components, and the combining element optical system may constitute a removable optical system for the imaging lens. good. It has a function as a module optical system that can be used as a front converter optical system or a rear converter optical system. This indicates that the aberration is individually corrected and the optical performance is ensured so that it can be mounted on other imaging optical systems. As a result, clear images of a plurality of subjects arranged at a plurality of different positions can be taken simultaneously. It can be used for general purposes as a front converter or a rear converter, and also functions as a detachable optical module (general-purpose optical module) including an optical system having a high system property and a mechanical mechanism.

(14th Embodiment)
In the present embodiment, a combining element optical system composed of fragmentary element optical systems and an aperture having a shape corresponding to one specific effective light beam of the fragmentary element optical systems, and a light-transmitting light shielding plate are both provided. It is characterized by having a mechanism for rotating around the optical axis of the imaging optical system.

An optical system system that separates and identifies images obtained by simultaneously imaging a plurality of subjects arranged at different positions by rotating the light shielding plate will be described below.
A composite element optical system part of a module optical system MD, which will be described later, is fixed, and a mask having one transmission hole corresponding to the size and shape of each segment equally divided in front or behind is newly inserted and arranged. Rotate the mask around the optical axis.
As a result, only the light beam transmitted from each segment is selectively extracted and imaged. An identification signal corresponding to the segment of the combining element optical system through which the light beam has passed is recognized, and periodically synchronized with a predetermined rotation angle from the reference position, and the corresponding cross section to be inspected is associated. As a result, it is possible to specify which fragment element optical system the luminous flux from each subject passes through and forms the image formed simultaneously. Alternatively, the same result can be obtained by fixing this mask and rotating the combining element optical system around the optical axis.

Further, by pasting this mask on a specific segment and rotating the synthesizing element optical system, it is possible to separate and image an image of a subject at a specific distance. Furthermore, by rotating the mask and the combining element optical system independently and simultaneously, the entire field of view of the subject at different positions and the multiple images at the respective positions can be separated and specified. This can be easily realized by setting the rotation period and imaging timing of each member.

In addition, it is possible to select the magnification, the number of divisions, and the type of the optical system suitable for the composite element optical system constituting these module optical systems MD. In this way, it is clear that simultaneous focusing is possible on a plurality of cross sections of the subject over a wide range. Further, it can be applied as a scanning means for a cross section of a subject for inputting a three-dimensional image. By constructing a confocal system for the focus image generated from the front and back of the subject, it is possible to clearly capture the cross section of each subject. In particular, an inexpensive and small imaging system can be easily constructed in the present invention.

When an afocal system is adopted as the synthesis element optical system, these can image a specific part of the subject, but cannot capture the entire field of view. Therefore, the light shielding plate is attached to a specific segment with the aperture aligned, and the combining element optical system is rotated, whereby only the image of the subject at a specific distance can be separated and the entire field of view can be captured. Further, as a practical method, the light shielding plate and the combining element optical system described above can be independently rotated to separate and specify the entire field of view of the subject at different positions and the multiple images at each position. This can be easily realized by setting the rotation period of each member and the imaging timing of the imaging device.

Furthermore, it is possible to measure a defocus characteristic of the imaging lens from the image contrast by arranging a plane chart object as a subject in this embodiment. Moreover, the focal depth of the imaging lens can also be measured from the obtained result.

(Fifteenth embodiment)
The present embodiment is characterized in that the combining element optical system is a module optical system and is detachable. 27 to 29 show the configuration of this embodiment.

An optical system including the synthesis element optical system 112 is referred to as a module optical system MD. The purpose can be achieved even if these mountable combining elements 112 are arranged at any location in the optical path. In order to ensure versatility, it is possible to easily separate the functions as a detachable module optical system MD. The detachable attaching / detaching mechanisms J1, J2, and J3 can be implemented by, for example, a bayonet mount or a screw mount.

FIG. 27 shows a configuration having functions usable as a module optical system MD (front converter optical system FC). This is a front converter optical system FC connected to the imaging optical system LB object side. This optical system FC has attachment / detachment mechanisms J1 and J2 that can be attached to and detached from the imaging optical system LB and a connecting means.
The lens barrel FC of the combining element optical system has a coupling mechanism J1 that can be attached to and detached from the lens barrel LB of the imaging optical system. The lens barrel LB of the imaging optical system is attached to the imaging camera C by the coupling mechanism J2 and is simultaneously imaged on the imaging element.

FIG. 28 shows a rear converter optical system RC connected to the image side of the imaging optical system LB. This optical system RC has a connecting means for attaching / detaching mechanisms J1 and J2 that can be attached to and detached from the imaging optical system LB and an attaching / detaching mechanism J3 to the imaging camera C. It has a function that can be used as a module optical system MD (rear converter optical system RC).
The lens barrel RC of this combining element optical system has a connecting means which is a detachable mechanism J1 that can be attached to and detached from the image side of the lens barrel LB of the imaging optical system. The lens barrel RC of the combining element optical system is connected to the intermediate lens barrel JB by a detachable attaching / detaching mechanism J2, and the intermediate lens barrel JB is attached to the imaging camera C by the detachable attaching / detaching mechanism J3 and is attached to the imaging element IM. Images are taken simultaneously.

FIG. 29 shows a dedicated module optical system MD (MC) disposed inside the image pickup optical systems LB1 and LB2, and the combining element optical is disposed in the vicinity of the aperture stop S.
FIG. 29 shows a dedicated built-in optical system MC mounted and arranged inside the imaging optical systems LB1 and LB2. The aperture stop S and the optical system MC have connecting means for attaching / detaching mechanisms J1 and J2 that can be attached to and detached from the imaging optical systems LB1 and LB2 and an attaching / detaching mechanism J3 that can be attached to and detached from the imaging camera C.

When the super-subject depth function is not required, it is assumed that the afocal optical system with a specific reference magnification or a dummy glass block is mounted with the imaging optical system. When the super subject depth optical system is realized, it may be replaced with a combining element optical system in which the fragment element light is a system. This is because in this combining element optical system, both the on-axis light beam and the off-axis light beam can be divided and controlled more evenly at the same time. The lens barrel MC of the composite element optical system has attachment / detachment mechanisms J1 and J2 that can be attached to and detached from the lens barrels LB1 and LB2 of the imaging optical system, and an attachment / detachment mechanism J3 of the imaging camera C. Images are taken simultaneously.

In general, the composite imaging magnification cannot be made constant in this arrangement. However, at this time, an imaging optical system in which the diaphragm space is a parallel light beam emitted from an on-axis object point is suitable in the system configuration. When images of subjects arranged at different positions are simultaneously imaged, an afocal synthetic speed element optical system is further inserted therein by using an imaging optical system as an afocal optical system or a telecentric optical system. By this insertion, an ultra-deep optical system capable of zooming can be configured.

In the eighth to fifteenth embodiments described above, for example, since multiple cross-sections of a subject surface of an arbitrary three-dimensional subject are simultaneously focused and those cross-sections are imaged at the same time, for example, multiple focusing is performed between the subject and the imaging optical system. Wear possible optics. For this reason, different sections are simultaneously focused without refocusing the imaging optical system.

However, in order to realize this, the combining optical system (multiple focusable optical system) composed of the above-described fragmentary element optical system is arranged and associated with each part of the fragmentary element optical system moving in focus in each azimuth direction. The light beam passes through this part. In this way, the incident light beam emitted from the different cross sections of the subject without direct mechanical movement is divided into four wavefronts as shown in FIG. 18, for example, in the cross section perpendicular to the optical axis. A plurality of images just focused on the same focal plane are simultaneously formed by the respective divided wavefront light beams.

Furthermore, the arrangement of the fragment element optical system in this way increases the amount of movement of each cross-section element optical system from the reference position, and the aberration due to this optical system increases, and therefore the imaging performance deteriorates. For this, it is necessary to cope with aberration correction including chromatic aberration. The aberration fluctuation due to the focus is corrected by adjusting the mutual lens interval of the lens components of the fragment element optical system.

Also, pay attention to specific light rays incident on the fragment element optical system. When passing through each fragment boundary, there is a light beam that passes through the plurality of fragment element optical systems. These rays are covered with a light shielding plate parallel to the optical axis at the boundary of the fragment element optical system, and blocked by a hood or the like. The stray light can be blocked. As a result, a clear image can be ensured only with the light beam formed by the image formation by each piece element optical system. As described above, there are a plurality of combined forms by combining the imaging optical system and the above-described multi-focus optical system, and the ultra-deep optical system as in the present invention can be easily configured.

In the above-described embodiment, a plurality of images focused on the same focus surface can be stably and simultaneously captured clearly and clearly without changing the focus of the imaging optical system in the mounting arrangement of the composite optical element. As a result, a high-resolution super-subject depth optical system can be realized. This makes it possible to realize a multifocal optical system capable of easily and simultaneously inspecting from the front surface to the back surface of a transparent inspection object having a depth.

In addition, it is possible to easily construct a small optical inspection apparatus corresponding to imaging a transparent three-dimensional object. In particular, a very large imaging optical system (large aperture, long focal length) is difficult to move at high speed. Focusing can be easily performed without moving the optical system. In addition, it is also possible to easily realize three-dimensional imaging and recording of a specific subject on different imaging planes by using the optical system in reverse. For example, a pick-up optical system for multi-media and multiple recording and writing can be easily realized. Therefore, it is possible to stably handle various recording and reproduction media. Similarly, ultra-deep imaging of an opaque three-dimensional object surface is easily possible.

1 is a perspective view illustrating a main configuration of an imaging apparatus according to a first embodiment of the present invention. It is a typical sectional view of the imaging device concerning a 1st embodiment. It is a perspective view which shows the principal part structure of the imaging device which concerns on 2nd Embodiment of this invention. It is a typical sectional view of an imaging device concerning a 2nd embodiment. It is a figure explaining the optical path between the subject and insertion plate in the imaging device concerning a 2nd embodiment. It is a perspective view which shows the principal part structure of the imaging device which concerns on 3rd Embodiment of this invention. It is a figure which shows the insertion plate used in the imaging device which concerns on 3rd Embodiment, (A) is a perspective view, (B) is the front view seen from the arrow VIIB-VIIB in (A), (C) is ( It is the side view seen from the arrow view VIIC-VIIC in A). It is a typical sectional view of an imaging device concerning a 3rd embodiment. It is a typical block diagram of the imaging device which concerns on 4th Embodiment. It is a typical sectional view of an imaging device concerning a 5th embodiment. It is a typical sectional view of an imaging device concerning a 6th embodiment. FIG. 10 is an optical path diagram for explaining that the same effect as that obtained when the insertion plate is inserted in front of the imaging lens can be obtained even when the insertion plate is inserted and installed behind the imaging lens. It is a typical sectional view of an imaging device concerning a 7th embodiment. The figure which showed the image formation relationship by an imaging lens. The figure which showed the relationship of the geometric optical arrangement | positioning of the focal depth of an imaging lens, and object depth. The figure which showed the image formation relationship by an afocal optical system. The figure which shows the synthetic | combination element optical system which concerns on 8th Embodiment. The figure which shows the synthetic | combination element optical system which concerns on 8th Embodiment. The figure which shows the relationship between a to-be-photographed object position and an image surface in the imaging relationship of a synthetic | combination element optical system and an imaging optical system of a front type. The figure which shows the relationship between a to-be-photographed object position and an image surface in the imaging relationship of a rear type synthetic | combination element optical system and an imaging optical system. The figure which shows the relationship between the several object position, the focusing arrangement | positioning of each fragmentary element optical system, and an image surface in the imaging relationship of the synthetic | combination element optical system and imaging optical system of 9th Embodiment. The figure which shows the relationship of several object position, the focusing arrangement | positioning of each fragmentary element optical system, and an image surface in the imaging relationship of the synthetic | combination element optical system and imaging optical system of 10th Embodiment. The figure which shows the relationship between the depth of focus and subject depth of the synthetic | combination optical system of an afocal optical system and an imaging optical system. The figure which shows the focusing state of a Kepler type optical telescope system. The figure which showed the focusing state of the Galileo type telescope system of 11th Embodiment. The figure which showed the in-focus state of the reverse Galileo type | formula telescope system of 12th Embodiment. The figure which shows 15th Embodiment. The figure which shows 15th Embodiment. The figure which shows 15th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Imaging device 2 Imaging lens 3 Insertion plate (parallel plate member)
4 Imaging surface 5 Imaging device 6 Image processing device 7 Display 8 Parallel flat glass Q1 Subject Q2 Subject (other subjects)
S1 Reference plane (subject)
S2 Reference plane (other subjects)
110, 111, 112 Synthesis element optical system A ₀ , A ₁ , A ₂ , A ₃ , A ₄ , A ₅ Fragment element optical system MD Module optical system

Claims (17)

In an imaging optical system that forms an image of a subject on an imaging surface,
A transparent parallel plate member is interposed between the subject and the imaging plane, and a part of the light exiting from the subject and condensed on the imaging plane passes through the parallel plate member. By doing so, the image of the subject and the image of the other subject separated from the subject in the optical axis direction by a distance corresponding to the thickness and refractive index of the parallel plate member are simultaneously An imaging optical system characterized in that an image is formed on an imaging plane. The parallel plate member is composed of a combination of a plurality of segments arranged in a circumferential direction around the optical axis, and the thickness and / or refractive index of the plurality of segments are different from each other. The imaging optical system according to claim 1. 3. The imaging optical system according to claim 1, wherein the parallel plate member is rotatable around the optical axis. An imaging apparatus comprising: the imaging optical system according to claim 1; and an imaging device that captures an image formed on the imaging surface. The imaging apparatus according to claim 4, wherein the imaging optical system has an aperture stop, and the parallel plate member constituting the imaging optical system is provided in the vicinity of the aperture stop. The parallel plate member constituting the imaging optical system and one or a plurality of optical elements other than the parallel plate member are configured as separable modules, and each module is arranged with respect to the optical axis of the imaging device. The imaging apparatus according to claim 4, wherein the imaging device can be changed. In an imaging optical system that forms an image of a subject on an imaging surface,
An optical element divided into a plurality of regions having different refractive powers between the subject and the imaging plane;
The imaging optical system, wherein the plurality of regions are respectively arranged at different positions in the optical axis direction. 8. The imaging optical system according to claim 7, wherein the optical element has a circular shape and is divided into a plurality of regions in the circumferential direction around the optical axis. The plurality of regions are arranged corresponding to the distance to a plurality of subjects arranged at different positions along the optical axis,
The imaging optical system according to claim 7 or 8, wherein the plurality of subjects are imaged on the same image plane by the optical element having the plurality of regions. The plurality of regions are movable in the optical axis direction,
The imaging optical system according to claim 7 or 8, wherein the plurality of subjects are imaged on the same image plane by the optical element having the plurality of regions. The imaging optical system according to claim 7, wherein the optical element is an afocal optical system or a telecentric optical system. The imaging optical system according to any one of claims 7 to 11, wherein the optical element is rotatable around an optical axis. The imaging optical system according to claim 7, wherein the optical element is rotatable with respect to the imaging element. The imaging optical system according to any one of claims 1 to 13, wherein the optical element is disposed in the vicinity of an aperture stop of the imaging optical system. A light-shielding plate having an opening having a shape corresponding to an effective light beam of a specific one of the plurality of regions;
Means for rotating the light shielding plate around an optical axis and separating and specifying an image obtained by simultaneously imaging the subject;
The imaging optical system according to any one of claims 1 to 12, wherein: The imaging optical system according to any one of claims 7 to 15,
An imaging apparatus, wherein the imaging apparatus is disposed between the subject and an imaging surface, and the imaging optical system is detachable from an imaging lens. The imaging optical system according to any one of claims 7 to 15,
An imaging apparatus, wherein the imaging apparatus is disposed between the subject and an imaging surface, and the imaging optical system is detachable from the imaging optical system.

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