JPH11202205A - Optical element and optical system using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an optical system to be more miniaturized by providing at least two of plural reflection areas with a common reflection plane and mutually crossing the optical paths of light determined in the plural reflection areas. SOLUTION: The optical element 10 forms a concave refraction plane R2 having negative refraction power, three reflection planes R3, R4 and R5 having positive or negative refraction power and concave refraction plane R6 having negative refraction power in the order of light beam passage from an object on its surface. Both two refraction planes R2 and R6 are composed of rotationally symmetric spherical surfaces and all the reflection planes R3-R5 are composed of anamorphic non-spherical surfaces symmetric only to a YZ plane. Light flux L1 from the object is made incident to the incident plane R2 of the optical element 10 after the quantity of incident light is regulated by an iris R1, reflected on the reflection planes R3-R5 and emitted from the emission plane R6 later and an image is formed through a low-pass filter and an infrared cut filter onto a final image forming plane R7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element and an optical system having the same. For example, the present invention relates to an optical element having an entrance / exit surface and a plurality of reflection surfaces provided on a surface of a transparent body, and an optical system having the same. These optical elements and optical systems are used for video cameras and still video cameras that form object images on the image sensor surface.
This is suitable for an image pickup apparatus such as a copying machine.

[0002]

2. Description of the Related Art Conventionally, various photographing optical systems using a reflecting surface such as a concave mirror or a convex mirror have been proposed. FIG.
FIG. 2 is a schematic diagram of a so-called mirror optical system including one concave mirror and one convex mirror.

In the mirror optical system shown in FIG. 1, an object light beam 104 from an object is reflected by a concave mirror 101, converges toward the object side, is reflected by a convex mirror 102, and forms an image on an image plane 103. ing.

This mirror optical system is based on a so-called Cassegrain-type reflection telescope, and the optical path of a long-lens telephoto lens system composed of a refractive lens is folded by using two opposing reflection mirrors. The purpose is to reduce the overall length of the optical system.

[0005] For the same reason, in the objective lens system constituting the telescope, for the same reason, in addition to the Cassegrain type, there are known many types in which the entire length of the optical system is shortened by using a plurality of reflecting mirrors.

As described above, a compact mirror optical system is obtained by efficiently folding the optical path by using a reflecting mirror instead of a lens of a photographic lens having a longer overall lens length than before.

However, a mirror optical system such as a Cassegrain-type reflection telescope generally has a problem that part of an object beam is vignetted by the convex mirror 102. This problem is caused by the presence of the convex mirror 102 in the area where the object light beam 104 passes.

In order to solve this problem, the reflecting mirror is used eccentrically so as to prevent the passing area of the object light beam 104 from being blocked by other parts of the optical system, that is, the principal ray of the light beam is transmitted along the optical axis. A mirror photographing optical system separated from the mirror 105 has also been proposed.

FIG. 12 is a schematic diagram of a mirror photographing optical system disclosed in the specification of US Pat. No. 3,674,334, in which the central axis of the reflecting mirror is decentered with respect to the optical axis so that the principal ray of the object light beam is emitted. The above problem of vignetting is solved away from the shaft.

The mirror optical system shown in FIG. 1 includes a concave mirror 111, a convex mirror 113, and a concave mirror 112 in the order in which light beams pass.
These are reflection mirrors which are originally rotationally symmetric with respect to the optical axis 114, as shown by two-dot broken lines in the figure. Of these, the concave mirror 111 uses only the upper side of the paper with respect to the optical axis 114, the convex mirror 113 uses only the lower side of the paper with respect to the optical axis 114, and the concave mirror 112 uses only the lower side of the paper with respect to the optical axis 114. The principal ray 116 is separated from the optical axis 114 to constitute an optical system in which vignetting of the object light beam 115 is eliminated.

FIG. 13 is a schematic diagram of a mirror optical system disclosed in the specification of US Pat. No. 5,063,586. The mirror optical system shown in the figure solves the above problem by decentering the central axis of the reflection mirror itself with respect to the optical axis and separating the principal ray of the object light beam from the optical axis.

In FIG. 1, when the vertical axis of the object plane 121 is defined as an optical axis 127, the convex mirror 12
2. The central coordinates and central axes of the respective reflecting surfaces of the concave mirror 123, the convex mirror 124 and the concave mirror 125 (the axes connecting the center of the reflecting surface and the center of curvature of the surface) 122a, 12
3a, 124a and 125a are eccentric with respect to the optical axis 127. In this figure, by appropriately setting the amount of eccentricity and the radius of curvature of each surface at this time, vignetting of the object light beam 128 by each reflection mirror is prevented, and the object image is efficiently formed on the image forming surface 126. I have.

In the specifications of US Pat. No. 4,737,021 and the specification of US Pat. No. 4,265,510, a configuration in which a part of a reflection mirror rotationally symmetric with respect to the optical axis is used to avoid vignetting, or the center axis of the reflection mirror itself is used. There is disclosed a configuration in which the optical axis is decentered with respect to the optical axis to avoid vignetting.

FIG. 14 shows an afocal optical system for observation using four reflecting surfaces disclosed in the specification of US Pat. No. 5,309,276. In the figure, a light beam from an object is divided into a first mirror 201, a second mirror 202, and a third mirror 201.
The third and fourth mirrors 203 and 204 are arranged so that they are reflected by the mirror 203, pass twice before the first mirror 201, exit perpendicular to the incident light, and form an image on the pupil 205. . At 205, the pupil of the observer is located.

Conventionally, an optical prism such as a pentagonal roof prism or a Porro prism used for a finder system or the like has a large number of reflecting surfaces as one block.

In these prisms, since a plurality of reflecting surfaces are integrally formed, the relative positional relationship between the respective reflecting surfaces is made with high precision, and it is not necessary to adjust the positions of the reflecting surfaces. However, the main function of these prisms is to reverse the image by changing the traveling direction of the light beam, and each reflecting surface is formed of a plane.

On the other hand, a photographing optical system in which a reflecting surface of a prism has a curvature (refractive power) is also known.

FIG. 15 is a schematic view of a main part of an observation optical system disclosed in the specification of US Pat. No. 4,775,217. The observation optical system observes the scenery of the outside world and observes the display image displayed on the information display body while overlapping the scenery.

In this observation optical system, the display light flux 145 emitted from the display image of the information display body 141 is incident from the incident surface 148 of the prism body, is reflected by the surface 142 and faces the object side, and is formed by a half mirror. The light enters the concave surface 143. After being reflected by the concave surface 143, the display light flux 1
45 is a substantially parallel light beam due to the refracting power of the concave surface 143, and after refracting and transmitting through the surface 142, the pupil 144 of the observer
To make the observer recognize the enlarged virtual image of the display image.

On the other hand, an object light beam 146 from the object enters a surface 147 substantially parallel to the reflection surface 142, and is refracted to reach a concave surface 143 formed by a half mirror. A semi-transmissive film is deposited on the concave surface 143, and a part of the object light beam 146 is
43 and refraction through surface 142, the pupil 14 of the observer
4 is incident. As a result, the observer visually recognizes the display image in the outside scenery while overlapping.

FIG. 16 is a schematic view of a main part of an observation optical system disclosed in Japanese Patent Application Laid-Open No. 2-279516. This observation optical system also observes the scenery of the outside world and also observes the display image displayed on the information display body in an overlapping manner.

In this observation optical system, the display light beam 154 emitted from the information display 150 passes through the plane 157 constituting the prism Pa, enters the prism Pa, and enters the reflecting surface 151 formed of a paraboloid. The display light beam 154 is reflected by the reflection surface 151 to become a convergent light beam and forms an image on the focal plane 156. At this time, the display light flux 154 reflected by the reflection surface 151 is divided into two parallel planes 1 constituting the prism Pa.
Focal plane 156 with total reflection between 57 and plane 158
, Thereby achieving a reduction in the thickness of the entire optical system.

Next, the display light beam 154 emitted as divergent light from the focal plane 156 is incident on a parabolic half mirror 152 while being totally reflected between the planes 157 and 158, and is reflected by the half mirror plane 152. At the same time
Due to the refractive power, an enlarged virtual image of the display image is formed, and the light flux becomes a substantially parallel light beam, passes through the surface 157 and enters the pupil 153 of the observer, thereby causing the observer to recognize the display image.

On the other hand, the object light beam 155 from the outside passes through the surface 158b constituting the prism Pb, passes through the half mirror 152 formed of a paraboloid, passes through the surface 157, and enters the pupil 153 of the observer. The observer visually recognizes the displayed image in an overlapping manner in the outside scenery.

Further, as examples of using an optical element on the reflecting surface of a prism, for example, Japanese Patent Application Laid-Open Nos.
There is an optical head for an optical pickup disclosed in Japanese Patent No. 139612 or the like. These devices reflect light from a semiconductor laser on a Fresnel surface or a hologram surface, form an image on a disk surface, and guide reflected light from the disk to a detector.

On the other hand, as shown in FIG.
Using a plurality of curved reflecting mirrors and an optical element integrally formed with a flat reflecting surface, it is possible to reduce the size of the entire mirror optical system and to improve the arrangement accuracy (assembly accuracy) of the reflecting mirror that is common in mirror optical systems. A loosened mirror optical system is proposed. In FIG. 17, reference numeral 51 denotes an example of an optical element in which a plurality of curved reflecting surfaces having a curvature are integrally formed, and 51 denotes a concave refracting surface R2, a concave mirror R3, and a convex mirror R in order from the object side.
4. An optical element composed of five reflecting surfaces of concave mirror R5, convex mirror R6, and concave mirror R7, and a convex refracting surface R8.
The direction of the reference axis incident on 1 and the direction of the reference axis emerging from the optical element 51 are substantially parallel and opposite. 52 is an optical correction plate such as a quartz low-pass filter or an infrared cut filter, 53 is an imaging element surface such as a CCD, and 54 is an optical element 5
A diaphragm 55 disposed on the object side 1 is a reference axis of the photographing optical system.

17, the light 56 from the object enters the concave refracting surface R2 of the optical element 51 after the amount of incident light is regulated by the stop 54.

The light incident on the concave refraction surface R2 is
After the object light 56 is diverged by the power of 2, the reflected light is reflected by the concave mirror R3, and the object image is primarily formed on the intermediate image plane N1 by the power of the concave mirror.

The object light 6 primarily formed on the intermediate image forming plane N1
Are convex mirror R4, concave mirror R5, convex mirror R6, concave mirror R7
The object light 6 which reaches the convex refraction surface R8 while being affected by the power of each of the reflecting mirrors while being repeatedly reflected by the object mirror 6 is refracted by the power of the convex refraction surface R8. Form an image.

As described above, the optical element 51 functions as a lens unit having desired optical performance and a positive power as a whole while repeating refraction by the incident / exit surface and reflection by a plurality of curved reflecting mirrors having a curvature. I have.

This type of mirror optical system is disclosed in Japanese Patent Application Laid-Open No. 9-2581.
It is also disclosed in Japanese Patent Publication No. 04-2004.

[0032]

The present invention relates to an improvement of an optical element and an optical system shown in FIG. 17 and Japanese Patent Application Laid-Open No. 9-258104, and an optical element smaller than these optical elements and It is an object of the present invention to provide an optical system smaller than the above optical system.

[0033]

An optical element according to the present invention comprises: (1-1) a plurality of reflection regions each having a curved surface for sequentially reflecting light, and at least two reflection regions among the plurality of reflection regions; Each has a common reflection surface, and the optical paths (reference axes) of the light defined by the plurality of reflection areas intersect.

In particular, (1-1-1) the plurality of reflection areas are supplied to the surface of a transparent body, and the light incident on the inside of the transparent body from a certain area of the transparent body is reflected by the plurality of reflection areas. The light is sequentially reflected by the region, propagates inside the transparent body, and then exits from another region of the transparent body. (1-1-2) The reference axes of the two reflection areas having the common reflection surface coincide with each other.

(1-2) a plurality of reflection areas for sequentially reflecting light, wherein at least two of the plurality of reflection areas have a common reflection surface and are defined by the plurality of reflection areas; The optical paths (reference axes) of the light intersect with each other, each of the reflection surfaces forming the plurality of reflection areas is inclined with respect to the reference axis, and
There is no symmetry plane that can define a pair of planes symmetric about it,
Alternatively, it is characterized by being made up of one aspherical surface.

In particular, (1-2-1) the plurality of reflection areas are supplied to a surface of a transparent body, and the light incident on the inside of the transparent body from a certain area of the transparent body is reflected by the plurality of reflection areas. The light is sequentially reflected by the region, propagates inside the transparent body, and then exits from another region of the transparent body. (1-2-2) The positions of the reference axes of the two reflection regions having the common reflection surface are coincident. (1-2-3) The shape of the reflection surface of the reflection area is A = (a + b) ・ (y ²・ cos ² t + x ² ) B = 2a ・ b ・ cos t (1 + {(ba ) ・ Y ・ sin t / (2a ・ b)} + [1 + {(ba) ・ y ・
sin t / (a ・ b)}-{y ² / (a ・ b)}-{4a ・ b ・ cos ² t + (a + b) ² sin ² t} x ²
/ (4a ² b ² cos ² t)] ^1/2 ], z = A / B + C02y ² + C11xy + C20x ² + C03y ³ + C12xy ² + C21x ² y + C04y ⁴ +
C13xy ³ + C22x ² y ² + C31x ³ y + C40x ⁴ +… C03 ≠ C21 ≠ t ≠ 0 Furthermore, C02 ≠ C20 C04 ≠ C40 ≠ C22 / 2. (1-2-4) The shape of the reflection surface of the reflection area is A = (a + b) · (y ² · cos ² t + x ² ) B = 2a · b · cos t [1 + {(ba ) ・ Y ・ sin t / (2a ・ b)} + [1 + {(ba) ・ y ・
sin t / (a ・ b)}-{y ² / (a ・ b)}-{4a ・ b ・ cos ² t + (a + b) ² sin ² t} x ²
/ (4a ² b ² cos ² t)] ^1/2 ], z = A / B + C02y ² + C11xy + C20x ² + C03y ³ + C12xy ² + C21x ² y + C04y ⁴ +
C13xy ³ + C22x ² y ² + C31x ³ y + C40x ⁴ + ... C03 ≠ C21 ≠ t ≠ 0 Further, it is characterized in that it is designed based on C02 ≠ C20 C04 ≠ C40 ≠ C22 / 2.

The optical system of the present invention is characterized in that the optical system has (2-1) one or more optical elements of the constitution (1-1) or (1-2).

The device of the present invention is characterized in that it has (3-1) one or more optical elements of the constitution (1-1) or (1-2).

In particular, (3-1-1) the optical element is a component of an optical system for photographing, observing, or measuring.

The optical element of the present invention comprises: (4-1) a plurality of reflection areas for sequentially reflecting light, each of the plurality of reflection areas being a curved surface, and at least two reflection areas in the reflection area. They have a common reflecting surface, and the positions of the reference axes in the two reflecting regions having the common reflecting surface coincide with each other.

In particular, (4-1-1) the plurality of reflection areas are supplied to the surface of a transparent body, and the light incident on the inside of the transparent body from a certain area of the transparent body is reflected by the plurality of reflection areas. It is characterized in that the light is sequentially reflected by a region, propagates inside the transparent body, and then exits from another region of the transparent body.

(4-2) There are a plurality of reflection areas for sequentially reflecting light, at least two of the reflection areas have a common reflection surface, and the common reflection surface is The positions of the reference axes in the two reflection regions have the same position, and each of the reflection surfaces forming the plurality of reflection regions is inclined with respect to the reference axis and defines a pair of surfaces symmetric with respect thereto. It is characterized in that it is an aspheric surface having no two or more symmetric planes.

In particular, (4-2-1) the plurality of reflection areas are supplied to the surface of a transparent body, and the light incident on the inside of the transparent body from a certain area of the transparent body is reflected by the plurality of reflection areas. The light is sequentially reflected by the region, propagates inside the transparent body, and then exits from another region of the transparent body. (4-2-2) The shape of the reflecting surface of the reflecting area is A = (a + b) · (y ² · cos ² t + x ² ) B = 2a · b · cos t [1 + {(ba ) ・ Y ・ sin t / (2a ・ b)} + [1 + {(ba) ・ y ・
sin t / (a ・ b)}-{y ² / (a ・ b)}-{4a ・ b ・ cos ² t + (a + b) ² sin ² t} x ²
/ (4a ² b ² cos ² t)] ^1/2 ], z = A / B + C02y ² + C11xy + C20x ² + C03y ³ + C12xy ² + C21x ² y + C04y ⁴ +
C13xy ³ + C22x ² y ² + C31x ³ y + C40x ⁴ +… C03 ≠ C21 ≠ t ≠ 0 Furthermore, C02 ≠ C20 C04 ≠ C40 ≠ C22 / 2. (4-2-3) The shape of the reflection surface of the reflection area is A = (a + b) · (y ² · cos ² t + x ² ) B = 2a · b · cos t [1 + {(ba ) ・ Y ・ sin t / (2a ・ b)} + [1 + {(ba) ・ y ・
sin t / (a ・ b)}-{y ² / (a ・ b)}-{4a ・ b ・ cos ² t + (a + b) ² sin ² t} x ²
/ (4a ² b ² cos ² t)] ^1/2 ], z = A / B + C02y ² + C11xy + C20x ² + C03y ³ + C12xy ² + C21x ² y + C04y ⁴ +
C13xy ³ + C22x ² y ² + C31x ³ y + C40x ⁴ + ... C03 ≠ C21 ≠ t ≠ 0 Further, it is characterized in that it is designed based on C02 ≠ C20 C04 ≠ C40 ≠ C22 / 2.

The optical system according to the present invention is characterized in that (5-1) one or more optical elements having the configuration (4-1) or (4-2) are provided.

The apparatus of the present invention is characterized in that (6-1) one or more optical elements having the configuration (4-1) or (4-2) are provided.

In particular, (6-1-1) the optical element is a component of an optical system for photographing, observing, or measuring.

[0047]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical element according to the present invention has a plurality of reflection areas for sequentially reflecting light, each of the plurality of reflection areas is formed of a curved surface, and at least two of the reflection areas are provided.
The plurality of reflection areas have a common reflection surface, and the optical paths (reference axes) of the light defined by the plurality of reflection areas intersect.

Further, another optical element according to the present invention has a plurality of reflection regions for sequentially reflecting light, at least two reflection regions in the reflection region have a common reflection surface, and The optical paths (reference axes) of the light defined by the plurality of reflection regions intersect, and each reflection surface forming the plurality of reflection regions is inclined with respect to the reference axis and defines a pair of surfaces symmetric with respect thereto. An aspherical surface having no more than two symmetric planes (meaning 0 or 1). This aspherical surface is represented by equation (1) in the specification text, and is designed based on equation (1).

Another optical element according to the present invention has a plurality of reflection areas for sequentially reflecting light, each of the plurality of reflection areas is formed of a curved surface, and at least two reflection areas in the reflection area are common to each other. And the positions of the reference axes in the two reflection regions having the common reflection surface coincide with each other.

Another optical element according to the present invention has a plurality of reflection areas for sequentially reflecting light, at least two of the reflection areas have a common reflection surface, and The positions of the reference axes in the two reflection regions having the reflection surfaces coincide with each other, and each of the reflection surfaces forming the plurality of reflection regions is inclined with respect to the reference axis, and is symmetric with respect to the reference axis. Is an aspherical surface having no more than two symmetry planes (meaning 0 or 1) that can define the surface of. This aspherical surface is represented by equation (1) in the specification text, and is designed based on equation (1).

In each of the above optical elements, the plurality of reflection areas are supplied to the surface of a transparent body, and the light incident on the inside of the transparent body from a certain area of the transparent body is reflected by the plurality of reflection areas. An element that is sequentially reflected and propagates through the inside of the transparent body and then exits from another area of the transparent body, and a plurality of reflecting mirrors that define the plurality of reflecting areas (the number of mirrors is one or more than the number of reflecting areas) ) Having a hollow structure.

In each of the above optical elements, there is a form in which the positions of the reference axes in the two reflection areas having the common reflection surface coincide with each other, and a form in which the reference axes do not coincide with each other.

The optical system of the present invention has one or a plurality of the above optical elements.

The device of the present invention has one or more of the above optical elements. In this device, the optical element is a component of an optical system for photographing, observing, or measuring, for example.

Before describing the embodiment of the optical system (photographing optical system) using the optical element of the present invention, the description of the configuration of the optical element of the present embodiment and the common matters of the entire embodiment will be described. This will be described with reference to FIG.

FIG. 10 is an explanatory diagram of a coordinate system that defines configuration data of a photographing optical system (optical system) using the optical element of the present invention. According to the embodiment of the present invention, 1 which advances from the object side to the image plane
The i-th surface along one light beam (shown by a dashed line in FIG. 10 and referred to as a reference axis light beam) is defined as an i-th surface.

In FIG. 10, a first surface R1 is a stop, a second surface R2 is a refracting surface coaxial with the first surface R1, a third surface R3 is a reflecting surface tilted with respect to the second surface R2, and a fourth surface R4. R4 and the fifth surface R5 are reflection surfaces shifted and tilted with respect to the respective front surfaces, and the sixth surface R6 is a refraction surface shifted and tilted with respect to the fifth surface R5. Each surface from the second surface R2 to the sixth surface R6 is formed on the surface of one transparent body made of a medium such as glass or plastic, and forms the optical element 10.

In the configuration shown in FIG. 10, the second
The medium up to the surface R2 is air, the common medium from the second surface R2 to the sixth surface R6, the medium from the sixth surface R6 to the seventh surface R7 such as a lens surface or a reflecting surface or an image forming surface (not shown). Is composed of air.

Since the photographing optical system of the present invention is a decentered optical system, each surface constituting the optical system does not have a common optical axis.
Accordingly, in the embodiment of the present invention, first, an absolute coordinate system having the origin at the center of the effective beam diameter of the first surface R1 is set.

In the embodiment of the present invention, the center point of the effective beam diameter of the first surface R1 is set as the origin TO, and the path of the light beam (reference axis light beam) passing through the origin and the center of the final imaging plane. Is defined as the reference axis ST of the optical system. Further, the reference axis ST in the present embodiment has a direction (direction). The direction in which the reference axis ray travels during imaging is positive.

In the embodiment of the present invention, the reference axis serving as the reference of the optical system is set as described above. However, the method of determining the reference axis of the optical system depends on the optical design, the aberration, or the optical axis. An axis that is convenient for expressing each surface configuration of the system may be used. For example, the path of a light ray passing through the center of the image plane and either the entrance pupil or the exit pupil or the center of the first surface or the center of the final surface of the optical system is set as a reference axis serving as a reference of the optical system. Is also good.

In the embodiment of the present invention, the reference axis is
Passing through the first surface R1, that is, the center point of the effective beam diameter of the stop surface,
The path is set such that a ray (reference axis ray) reaching the center of the final image plane is refracted and reflected by each refraction surface and reflection surface. The order of each surface is set in the order in which the reference axis rays are refracted and reflected.

Accordingly, the reference axis passing through the center of the stop (plane) finally reaches the center of the image plane while changing its direction along the set order of the planes according to the law of refraction or reflection.

The tilt surfaces such as the tilted reflecting surface and the tilted refracting surface constituting the optical system of each embodiment of the present invention are as follows.
Basically, everything is tilted in the same plane. Therefore, each axis of the absolute coordinate system (X, Y, Z) is determined as follows.

Z axis: Reference axis toward the second surface R2 through the origin TO Y axis: X in the tilt plane (in the paper plane of FIG. 1) through the origin TO
X-axis: A straight line that passes through the origin TO and is perpendicular to each of the Z and Y axes (a straight line that is perpendicular to the plane of FIG. 1).

In order to express the surface shape of the i-th surface constituting the optical system, the reference axis ST and the i-th surface can be expressed by expressing the shape of the surface in an absolute coordinate system (X, Y, Z). The configuration data of the optical system of the present invention is displayed because it is easier to understand the shape of the surface by setting the local coordinate system with the intersection as the origin and expressing the surface shape of the surface in the local coordinate system. In this case, the surface shape of the i-th surface is represented by a local coordinate system.

However, in the present invention, a certain surface reflects a light beam a plurality of times in a part of the effective area. At that time, the reference point for the first reflection does not always coincide with the reference point for the second and subsequent reflections on that surface. That is, the reference point may not coincide with the origin of the local coordinate system.

In such a case, the configuration data of the optical system also describes the second and subsequent reflection surfaces, but it should be noted that this is the same surface as the first reflection surface.

The tilt angle of the i-th surface in the YZ plane is represented by an angle θi (unit: °) with the counterclockwise direction being positive with respect to the Z axis of the absolute coordinate system. Therefore, in the embodiment of the present invention, the origin of the local coordinates of each surface is on the YZ plane in FIG. There is no eccentricity of the plane in the XZ plane and the XY plane.
Further, y, z of local coordinates (x, y, z) of the ith surface
The axis is inclined at an angle θi in the YZ plane with respect to the absolute coordinate system (X, Y, Z), and is specifically set as follows.

Z-axis: a straight line passing through the origin of the local coordinate system and forming an angle θi in the YZ plane in the YZ plane with respect to the Z direction of the absolute coordinate system. X-axis: A straight line that passes through the origin of local coordinates and is perpendicular to the YZ plane.

Di is a scalar quantity representing the distance between the origins of the local coordinates of the i-th surface and the (i + 1) -th surface, Ndi,
νdi is the refractive index and Abbe number of the medium between the i-th surface and the (i + 1) -th surface. The aperture and the final image plane are also displayed as one plane.

In some cases, the reference axis does not coincide with the origin of the local coordinates. In this case, Di is not shown because it has no meaning.

Certain embodiments of the optical system of the present invention have at least one spherical surface and one or more rotationally asymmetric aspheric surfaces. Among them, the spherical portion has a radius of curvature Ri as a spherical shape. The sign of the radius of curvature Ri is defined as minus when the center of curvature is on the first surface side along the reference axis (dashed line in FIG. 1) that advances from the first surface to the image surface, and is positive when the center of curvature is on the imaging surface side. I have.

The spherical surface has a shape represented by the following equation:

[0075]

(Equation 1) Further, the rotationally asymmetric aspherical shape in the present invention can be expressed by the following equation (1). Here, a, b, and t are coefficients representing the surface shape. : A = (a + b) ・ (y ²・ cos ² t + x ² ) B = 2a ・ b ・ cos t [1 + {(ba) ・ y ・ sin t / (2a ・ b)} + [1 + {(ba) ・ y ・
sin t / (a ・ b)}-{y ² / (a ・ b)}-{4a ・ b ・ cos ² t + (a + b) ² sin ² t} x ²
/ (4a ² b ² cos ² t)] ^1/2 ] The shape of the rotationally asymmetric aspherical surface in the present invention is a plane-symmetrical shape in which only the yz plane is a symmetric plane by setting only the odd-order terms to 0 using only the even-order terms related to x in the above-mentioned curved surface equation. is there. At this time, the following conditions are satisfied.

C03 ≠ C21 ≠ t ≠ 0 Further, C02 ≠ C20 C04 ≠ C40 ≠ C22 / 2 In the present invention, an aspherical surface having no plane of symmetry can be used.

In each of the embodiments of the present invention, as in the case of FIG. 10, the first surface is a stop. The horizontal half angle of view uY is the maximum angle of view of the light beam incident on the aperture stop R1 in the YZ plane of FIG.
Is the maximum angle of view of the light beam incident on the stop R1 in the XZ plane. Also, the diameter of the opening of the stop R1 as the first surface is shown as the stop diameter. This is related to the brightness of the optical system. In such an optical system, since the entrance pupil is located on the first surface, the entrance pupil diameter is equal to the stop diameter.

Further, in the numerical examples, the brightness related to the imaging at a finite distance is indicated by the numerical aperture on the object side (numerical aperture). Also, the effective image range on the image plane is shown as an image size. The image size is represented by a rectangular area in which the size of the local coordinate in the y direction is horizontal and the size in the x direction is vertical.

In each embodiment, the size of the optical system is shown. The size is a size determined by the effective beam diameter.

Further, the lateral aberration chart is shown for each embodiment in which the configuration data is listed. In each embodiment, the horizontal angle of incidence and the vertical angle of incidence on the stop R1 are respectively (u
Y, uX), (0, uX), (−uY, uX), (u
FIG. 4 shows lateral aberration diagrams in the Y direction and the X direction of a light beam of (Y, 0) (0, 0) and (−uY, 0). In the lateral aberration diagram, the horizontal axis represents the height of incidence on the pupil, and the vertical axis represents the amount of aberration. In each embodiment, since each surface is basically a plane-symmetrical shape with the yz plane as a plane of symmetry, the plus and minus directions of the vertical angle of view are the same even in the lateral aberration diagram. For this reason, a lateral aberration diagram in the minus direction is omitted.

Next, each embodiment of the optical element of the present invention and an optical system (photographing optical system) having the same will be described.

FIGS. 1 and 2 are schematic views in the YZ section of Embodiment 1 when the optical element of the present invention is applied to a photographing optical system. The first embodiment has a shooting angle of view with a horizontal half angle of view of 12.2 degrees and a vertical half angle of view of 16.1 degrees.

1 and 2, reference numeral 1 denotes a photographing optical system. Reference numeral 10 denotes an optical element having a plurality of curved reflecting surfaces (back reflecting mirrors), which is made of a transparent material such as glass or plastic. The optical element 10 has a concave refracting surface (incident surface) R2 having a negative refractive power (= 1 / focal length), a reflecting surface R3, a reflecting surface R4,
The reflection surface R5 has three reflection surfaces having positive or negative refractive power and a concave refractive surface (exit surface) R6 having negative refractive power. R1 is a stop (entrance pupil) arranged on the object side of the optical element 10. An optical correction plate (optical block) such as a low-pass filter or an infrared cut filter is usually provided between the exit surface R6 and the final image forming surface R7, but is not shown in FIG.

R7 is a final image forming plane on which an image pickup surface of an image pickup device (image pickup medium) such as a CCD is located. The photographing optical system 1 has an optical element 10 and an optical block (not shown). Reference numeral 11 denotes a reference axis of the photographing optical system 1.

Each of the two refraction surfaces R2 and R6 of the optical element 10 is formed of a rotationally symmetric spherical surface.
R5 is made of an anamorphic aspheric surface symmetric only with respect to the YZ plane.

As shown in FIG. 2, the reflecting surfaces R3 and R5 are composed of a part of the same curved reflecting surface 100, and the reflecting surfaces of the effective reflection areas are partially overlapped (common).

Next, the image forming operation in this embodiment will be described. The light beam L1 from the object enters the incident surface R2 of the optical element 10 after the amount of incident light is regulated by the stop R1, is reflected by the reflecting surfaces R3, R4, R5, and then exits from the exit surface R6. An image is formed on the final image plane R7 via the illustrated low-pass filter and infrared cut filter.

In the present embodiment, the entrance surface R of the optical element 10
2 is different from the direction of the reference axis 11 emitted from the exit surface R6. Further, the reference axes including the incoming and outgoing light are all on the plane of the paper (YZ plane).

As described above, the optical element 10 is a lens unit having desired optical performance and having a positive refractive power as a whole by the refractive power of the entrance / exit surface and the refractive power of the plurality of curved reflecting mirrors therein. It is functioning.

In each surface in the photographing optical system 1, a light ray passing through the center of the stop R1 defined in the photographing optical system 1 among rays emitted from the center of the object plane is set as a reference axis light ray, and is incident on each surface. When the reference axis ray is the incident reference axis of the surface, the reference ray emitted from each surface is the emission reference axis of the surface, and when the intersection of the incident / emission reference axis and each surface is the reference point, Is an Off-Axial reflecting surface in which the incident / exit reference axis is inclined with respect to the normal at the reference point.

The optical element 10 is an off-axial optical element in which two refracting surfaces and two or more off-axial reflecting surfaces are integrally formed on the surface of a transparent body.

Each reflecting surface is composed of two orthogonal surfaces (YZ plane,
(XZ plane), it is designed using Equation (1) so that the refractive power is different and has only one plane of symmetry, and there is little decentering aberration.

In this embodiment, focusing on a short-distance object is performed by moving the entire photographing optical system 1 to the image pickup surface R of the image pickup device.
7 by moving it.

FIG. 3 shows a lateral aberration diagram of the photographing optical system of the present embodiment when the object is at infinity. In the aberration diagrams, the dotted line represents the c-line, the solid line represents the d-line, and the dashed line represents the f-line. As shown in the figure, according to the present embodiment, a well-balanced aberration correction state is obtained.

Next, effects of the present embodiment will be described.

In this embodiment, the reflecting surfaces R3 and R5
Are part of the same surface. That is, the function formula describing the surface shape of the surfaces R3 and R5 is the same (common) as the local coordinate origin position. As shown in FIG. 2, the effective reflection areas at the time of each reflection partially overlap each other, and have a common reflection surface.

In this embodiment, the number of reflection surfaces of the optical element 1 is two, but the number of reflections from the time when an arbitrary light ray enters the optical element 1 until the light ray exits is three. It is.

As described above, the optical element 1 has the entrance and exit surfaces R2 and R2.
6 and the refracting power of a plurality of curved reflecting mirrors therein function as a lens unit having an image forming action as a whole. The effective use of the reflecting surface is achieved by superimposing the effective area of the number of reflecting surfaces. By doing so, a small optical element is achieved.

FIGS. 4 and 5 are schematic diagrams of the photographic optical system according to the second embodiment of the present invention in the YZ section. In the present embodiment, the object side is a telecentric optical system, and has a photographing range of a horizontal object height of 1.3 and a vertical object height of 1.0.

4 and 5, reference numeral 1 denotes a photographing optical system. 1
Reference numeral 0 denotes an optical element having a plurality of curved reflecting surfaces, which is made of a transparent material such as glass or plastic. Optical element 10
Is a reflection of three positive or negative refractive powers of a concave refracting surface (incident surface) R1, a reflecting surface R2, a reflecting surface R34, and a reflecting surface R4 having negative refracting power on the surface in the order of passage of light rays from the object. Surface and concave refractive surface (exit surface) R5 having negative refractive power
Is formed. R0 is an object surface, R8 is a final image forming surface, and an image pickup surface of an image pickup device such as a CCD is located.

4 and 5, a light ray coming from the object side R0 is refracted by the refraction surface 1, and is reflected by the reflection surface R2, the reflection surface R3, and the reflection surface R4, respectively.
The light is refracted at 5 and forms an image on an image plane R6.

In this embodiment, the reflecting surfaces R2 and R4
Are part of the same surface. As shown in FIG. 5, the effective areas at the time of reflection of the surface R2 and the surface R4 partially overlap each other. Further, the refraction surface R1 and the reflection surface R3 are each a part of the same surface, but the effective area is as shown in FIG.
Some areas overlap with each other as shown in FIG.

FIG. 6 shows a lateral aberration diagram of the photographing optical system of the present embodiment. Only in the present embodiment, in the lateral aberration diagram, the horizontal axis is the object-side numerical aperture (numerical aperture).

FIGS. 7 and 8 are schematic views of the optical system according to the third embodiment of the present invention in the YZ section. The third embodiment has a shooting angle of view of a horizontal half angle of view of 3 degrees and a vertical half angle of view of 4 degrees.

In FIGS. 7 and 8, reference numeral 1 denotes a photographing optical system. 1
Reference numeral 0 denotes an optical element having a plurality of curved reflecting surfaces (surface reflecting mirrors). The optical element 10 is arranged in the order of passage of light rays from the object.
The reflecting surface R2, the reflecting surface R3, the reflecting surface R4, and the reflecting surface R5 form four reflecting surfaces having positive or negative refractive power. R
1 is a stop (entrance pupil) arranged on the object side of the optical element 10,
R6 is a final image plane.

In FIGS. 7 and 8, a light beam coming from the object side passes through the stop R1, is reflected by the reflecting surfaces R2, R3, R4, and forms an image on the image forming surface R6. In the present embodiment, the reflection surface R
2 and the reflection surface R5 are each part of the same surface. Surface R
As shown in FIG. 8, a part of the effective area at the time of reflection of the surface 2 and the area R5 overlaps each other.

In this embodiment, the reference point (reference axis (light ray) incident position) of the reflecting surface R2 and the reference point (reference axis (light ray) incident position) of the reflecting surface R5 coincide. That is, the reference axis ray is reflected twice at a certain point on a certain reflection surface at different incident angles.

In this embodiment, the number of reflecting surfaces of the optical element 10 is three,
The number of reflections from the time when the light is incident on the surface to the time when the light is emitted is four.

FIG. 9 shows a lateral aberration diagram of the photographing optical system of this embodiment.
Shown in As in the case of FIGS. 1, 2, 4 and 5, the optical system shown in FIGS. 7 and 8 is provided with a reflecting surface on the surface of glass or plastic, and the light is propagated inside the transparent body. It can also be.

In the above-described embodiment, an optical system constituted by using only one Off-Axial optical element having a reflecting surface for reflecting a light beam twice in the same region has been described, but the optical system of the present invention is not limited to this. It is not limited. For example, o
The use of a plurality of off-axis optical elements, the off-axis
The optical system may be configured by combining the s optical element with a normal optical element.

The optical element of the present invention is not limited to a photographing optical system, but can be applied to various optical systems such as an observation optical system and a measurement optical system.

Next, numerical examples of each embodiment of the present invention will be described.

[0113]

[Outside 1]

[0114]

[Outside 2]

[0115]

[Outside 3]

[0116]

According to the present invention, according to the conventional FIG.
An optical element and an optical system smaller than the optical element and the optical system disclosed in JP-A-9-258104 can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view of a YZ cross section according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of a YZ cross section according to the first embodiment of the present invention.

FIG. 3 is a lateral aberration diagram according to the first embodiment of the present invention.

FIG. 4 is a schematic diagram of a YZ cross section according to the second embodiment of the present invention.

FIG. 5 is a schematic diagram of a YZ cross section according to the second embodiment of the present invention.

FIG. 6 is a lateral aberration diagram according to the second embodiment of the present invention.

FIG. 7 is a schematic diagram of a YZ cross section according to a third embodiment of the present invention.

FIG. 8 is a schematic diagram of a YZ cross section according to a third embodiment of the present invention.

FIG. 9 is a lateral aberration diagram according to the third embodiment of the present invention.

FIG. 10 is an explanatory diagram of a coordinate system according to the embodiment of the present invention.

FIG. 11 is an explanatory view of a conventional Cassegrain type reflection telescope.

FIG. 12 is a schematic view of a main part of a conventional reflection type optical system.

FIG. 13 is a schematic view of a main part of a conventional reflection type optical system.

FIG. 14 is a schematic view of a main part of a conventional reflection type optical system.

FIG. 15 is a schematic view of a main part of a conventional reflection type optical system having a prism reflection surface.

FIG. 16 is a schematic view of a main part of a conventional reflection type optical system having a prism reflection surface.

FIG. 17 is a schematic view of a main part of a conventional reflection type optical system.

[Explanation of symbols]

 Reference Signs List 1 optical system 10 optical element Ri reflecting surface or refracting surface or stop

Claims (20)

[Claims] A plurality of reflection regions each having a curved surface for sequentially reflecting light; at least two of the plurality of reflection regions have a common reflection surface; An optical element wherein the optical paths of the light defined by the regions intersect. 2. The method according to claim 1, wherein the plurality of reflection areas are provided on a surface of a transparent body, and the light incident on the inside of the transparent body from a certain area of the transparent body is sequentially reflected by the plurality of reflection areas,
2. The optical element according to claim 1, wherein the light is emitted from another region of the transparent body after propagating inside the transparent body. 3. The optical element according to claim 1, wherein the positions of the reference axes of the two reflection regions having the common reflection surface coincide with each other. 4. A light path of the light having a plurality of reflection regions for sequentially reflecting light, wherein at least two reflection regions in the plurality of reflection regions have a common reflection surface and are defined by the plurality of reflection regions. Are intersecting, each reflecting surface forming the plurality of reflecting regions is inclined with respect to a reference axis, and there is no or one asymmetric surface which can define a pair of surfaces symmetric with respect thereto. An optical element characterized by comprising: 5. The plurality of reflection areas are provided on a surface of a transparent body, and the light incident from inside a certain area of the transparent body to the inside of the transparent body is sequentially reflected by the plurality of reflection areas,
The optical element according to claim 4, wherein the light is emitted from another area of the transparent body after propagating inside the transparent body. 6. The optical element according to claim 4, wherein the positions of the reference axes of the two reflection regions having the common reflection surface coincide with each other. 7. The shape of the reflection surface of the reflection area is A = (a + b) · (y ² · cos ² t + x ² ) B = 2a · b · cos t [1 + {(ba) · y ・ sin t / (2a ・ b)} + [1 + {(ba) ・ y ・
sin t / (a ・ b)}-{y ² / (a ・ b)}-{4a ・ b ・ cos ² t + (a + b) ² sin ² t} x ²
/ (4a ² b ² cos ² t)] ^1/2 ], z = A / B + C02y ² + C11xy + C20x ² + C03y ³ + C12xy ² + C21x ² y + C04y ⁴ +
C13xy ³ + C22x ² y ² + C31x ³ y + C40x ⁴ + ... C03 ≠ C21 ≠ t ≠ 0 and C02 ≠ C20 C04 ≠ C40 ≠ C22 / 2 Optical element. 8. The shape of the reflection surface of the reflection area is as follows: A = (a + b) · (y ² · cos ² t + x ² ) B = 2a · b · cos t [1 + {(ba) · y ・ sin t / (2a ・ b)} + [1 + {(ba) ・ y ・
sin t / (a ・ b)}-{y ² / (a ・ b)}-{4a ・ b ・ cos ² t + (a + b) ² sin ² t} x ²
/ (4a ² b ² cos ² t)] ^1/2 ], z = A / B + C02y ² + C11xy + C20x ² + C03y ³ + C12xy ² + C21x ² y + C04y ⁴ +
C13xy ³ + C22x ² y ² + C31x ³ y + C40x ⁴ + ... C03 ≠ C21 ≠ t ≠ 0 Further, the design is based on C02 ≠ C20 C04 ≠ C40 ≠ C22 / 2. ,
The optical element of 5 or 6. 9. An optical system comprising one or more optical elements according to claim 1. Description: 10. An apparatus comprising one or more optical elements according to claim 1. Description: 11. The optical device according to claim 1, wherein the optical element is a component of an optical system for photographing, observing, or measuring.
0 device. 12. A plurality of reflection areas for sequentially reflecting light, the plurality of reflection areas each having a curved surface, and at least two reflection areas in the reflection area have a common reflection surface. An optical element, wherein the positions of reference axes in the two reflection areas having the common reflection surface coincide with each other. 13. The plurality of reflection areas are supplied to a surface of a transparent body, and the light incident from inside a certain area of the transparent body to the inside of the transparent body is sequentially reflected by the plurality of reflection areas, 13. The optical element according to claim 12, wherein the light is emitted from another region of the transparent body after propagating inside the transparent body. 14. A light emitting device comprising: a plurality of reflection regions for sequentially reflecting light; at least two of the reflection regions have a common reflection surface; and the two reflection regions have the common reflection surface.
The positions of the reference axes in the plurality of reflection regions coincide with each other, and each of the reflection surfaces forming the plurality of reflection regions is inclined with respect to the reference axis and can define a pair of surfaces symmetric with respect to the reference axis. Is an aspherical surface having no more than 2. 15. The plurality of reflection areas are provided on a surface of a transparent body, and the light incident from inside a certain area of the transparent body to the inside of the transparent body is sequentially reflected by the plurality of reflection areas, 15. The optical element according to claim 14, wherein the light is emitted from another region of the transparent body after propagating inside the transparent body. 16. The shape of the reflection surface of the reflection area is: A = (a + b) · (y ² · cos ² t + x ² ) B = 2a · b · cos t [1 + {(ba) · y ・ sin t / (2a ・ b)} + [1 + {(ba) ・ y ・
sin t / (a ・ b)}-{y ² / (a ・ b)}-{4a ・ b ・ cos ² t + (a + b) ² sin ² t} x ²
/ (4a ² b ² cos ² t)] ^1/2 ], z = A / B + C02y ² + C11xy + C20x ² + C03y ³ + C12xy ² + C21x ² y + C04y ⁴ +
C13xy ³ + C22x ² y ² + C31x ³ y + C40x ⁴ + ... C03 ≠ C21 ≠ t ≠ 0 Further, C02 ≠ C20 C04 ≠ C40 ≠ C22 / 2, wherein the optical element according to claim 14 or 15, . 17. The shape of the reflection surface of the reflection area is A = (a + b) · (y ² · cos ² t + x ² ) B = 2a · b · cos t [1 + {(ba) · y ・ sin t / (2a ・ b)} + [1 + {(ba) ・ y ・
sin t / (a ・ b)}-{y ² / (a ・ b)}-{4a ・ b ・ cos ² t + (a + b) ² sin ² t} x ²
/ (4a ² b ² cos ² t)] ^1/2 ], z = A / B + C02y ² + C11xy + C20x ² + C03y ³ + C12xy ² + C21x ² y + C04y ⁴ +
C13xy ³ + C22x ² y ² + C31x ³ y + C40x ⁴ + ... C03 ≠ C21 ≠ t ≠ 0 Further, it is designed based on C02 ≠ C20 C04 ≠ C40 ≠ C22 / 2.
Or 15 optical elements. 18. An optical system comprising one or a plurality of optical elements according to claim 12. 19. An apparatus comprising one or more optical elements according to claim 12. Description: 20. The optical device according to claim 1, wherein the optical element is a component of an optical system for photographing, observing, or measuring.
9 devices.