JPH1068885A - Optical element and optical system formed by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical element with environment resistance, to provide protection of reflection films and to decrease the ghost flare light by the incidence of unnecessary light by covering at least one surfaces of reflection surfaces and flanks with protective members. SOLUTION: The protective members 2 to 6 are formed on the respective reflection surfaces R4, R6, R7, R5, R3 over the entire part thereof. Metallic reflection films are formed by vapor deposition processing, etc., on the effective parts of these surfaces R3 to R7. The respective protective members 2 to 6 are respectively formed on these metallic reflection films. The transmittance over the entire system of the optical element is improved by increasing the reflectivity of the metallic reflection films formed on the surfaces of the respective reflection films. The metallic reflection films formed by vapor deposition, however, have a high probability that the films are corroded in the environmental state of a high temp., high humidity, etc. The protective members 2 to 6 are, thereupon, formed over the entire surface of the respective reflection surfaces R3 to R7 from above the metallic reflection films in order to assure the durability of the metallic reflection films in this case. Namely, the metallic reflection films are shut off and protected from the air by the protective members 2 to 6.

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 using the same, and more particularly, to a silver halide camera, a video camera,
It is suitable for a steel video camera, a copying machine, and the like.

[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. 12 is a schematic diagram of a main part of a so-called mirror optical system (reflection optical system) composed of one concave mirror and one convex mirror.

In the mirror optical system shown in FIG. 1, an object light beam 124 from an object is reflected by a concave mirror 121, converges toward the object side, is reflected by a convex mirror 122, and is reflected by an image plane.
Image at 123.

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 bent by using two opposing reflection mirrors. The purpose is to shorten the entire 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 bending the optical path by using a reflecting mirror instead of the lens of the photographing lens having a longer overall lens length.

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 122. This problem is caused by the presence of the convex mirror 122 in the area where the object light beam 124 passes.

In order to solve this problem, the reflecting mirror is used in an eccentric manner so as to prevent the passing area of the object light beam 124 from being blocked by other parts of the optical system, that is, the principal ray of the light beam.
A mirror optical system that separates 126 from the optical axis 125 has also been proposed.

FIG. 13 is a schematic view of a main part of a mirror optical system disclosed in US Pat. No. 3,674,334, which solves the above-mentioned vignetting problem by separating a principal ray of an object light beam from an optical axis. doing. The mirror optical system shown in the figure is a concave mirror in the order in which light beams pass.
There are a reflecting mirror 131, a convex mirror 132 and a concave mirror 133, each of which is originally a reflection mirror rotationally symmetric with respect to the optical axis 134, as shown by a two-dot broken line in the figure. Of these, concave mirror 13
1 is only the upper side of the paper with respect to the optical axis 134, and the convex mirror 132 is the optical axis
By using only the lower side of the drawing with respect to the optical axis 134 and the concave mirror 133 using only the lower side of the drawing with respect to the optical axis 134,
Is separated from the optical axis 134 to form an optical system in which vignetting of the object light beam 135 is eliminated.

FIG. 14 is a schematic view of a main part of a mirror optical system disclosed in 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 surface 141 is defined as an optical axis 147, the center coordinates and the center axis of the respective reflecting surfaces of the convex mirror 142, the concave mirror 143, the convex mirror 144 and the concave mirror 145 in the order of passage of the light flux The axes 142A, 143A, 144A, and 145A connecting the center of the reflecting surface and the center of curvature of the surface are eccentric with respect to the optical axis 147. 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 148 by each reflecting mirror is prevented, and the object image is efficiently formed on the image forming surface 146. I have.

In addition, US Pat. No. 4,737,021 and US Pat. No. 4,265,510 also disclose a configuration in which a part of a reflection mirror that is rotationally symmetric with respect to the optical axis is used to avoid vignetting, or the central axis of the reflection mirror is used as a light source. A configuration is disclosed in which the shaft is eccentric with respect to the shaft to avoid vignetting.

As described above, by decentering each reflecting mirror constituting the mirror optical system, it is possible to prevent vignetting of the object beam. However, each reflecting mirror must be arranged with a different decentering amount. The structure for mounting the reflection mirror becomes complicated, and it is very severe to secure the mounting accuracy.

As one method for solving this problem, a method has been proposed in which, for example, a mirror system is divided into one block to avoid errors in assembling optical components during assembly.

Conventionally, an optical prism used in a finder system of a camera, such as a pentagonal roof prism or a Porro prism, or a light beam from a photographing lens, such as a red light beam, is used as one in which many reflecting surfaces are formed as one block. There is an optical prism, such as a color separation prism, that separates light into three colors of green and blue and forms an object image based on each color light on a corresponding image sensor surface.

As a typical example of an optical prism, the function of a pentagonal roof prism often used in a single-lens reflex camera will be described with reference to a sectional view of a finder of the single-lens reflex camera in FIG.

In FIG. 15, 151 is a taking lens, 152 is a quick return mirror, 153 is a focusing surface, 154 is a condenser lens, 155 is a pentagonal roof prism, 15
6 is the eyepiece, 157 is the observer's pupil, 158 is the optical axis, 159
Is the image plane.

A light beam from a subject (not shown) is taken by a photographing lens.
After passing through 151, the light is reflected by the quick return mirror 152 in the upward direction of the camera, and forms an image on a focus plane 153 at a position equivalent to the image plane 159.

Behind the focusing surface 153, a photographing lens 151 is provided.
A condenser lens 154 for substantially forming an image of the exit pupil on the observer's pupil 157 is disposed, and a pentagonal roof prism 155 for rearranging the object image on the focusing surface 153 as an erect image is disposed behind the condenser lens 154. ing.

The entrance surface 15 of the pentagonal roof prism 155
The object light incident on 5a is reflected to the observer side by the reflecting surface 155c after the object image is inverted right and left by the roof surface 155b.

The object light emitted to the observer side by the reflection surface 155c passes through the emission surface 155d of the pentagonal roof prism 155, reaches the eyepiece 156, and is converted into substantially parallel light by the refractive power of the eyepiece 156. Thereafter, the object reaches the pupil 157 of the observer, and the object image is observed.

The main problem of these optical prisms, such as the pentagonal roof prism, is that the frequency of harmful ghost light that is incident on the prism from a position and angle other than the effective ray and that is accompanied by illegally incident light is high. Can be raised.

In the pentagonal roof prism having such a configuration, for example, a ghost light incident at an angle different from that of the effective ray as shown by an arrow in FIG. 15 is reflected on the roof surface 155b and the reflection surface 155c in this order, and then incident. Total reflection at surface 155a, 15
Inject from below 5d to the observation side.

When such ghost light is present, an image whose upside down is reversed appears on the lower side of the observation screen because the number of reflections is different from that of a normal effective light ray.

In order to remove the ghost light, in the pentagonal roof prism 155, the ghost light is usually removed by providing a light shielding groove 150 on the exit surface 205d of the pentagonal roof prism 155.

Further, the entire prism surface except for the entrance surface 155a and the exit surface 155d is covered with black paint so that the roof surface 15
The reflection film deposited on the reflection surface 5b and the reflection surface 155c protects the reflection film from environmental changes such as temperature and humidity, and also shields light rays from outside the prism.

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 accuracy, 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, an optical system in which a reflecting surface of a prism has a curvature is also known.

FIG. 16 is a schematic view of a main part of an observation optical system disclosed in US Pat. No. 4,775,217. This observation optical system is an optical system for observing an external scenery and observing a display image displayed on an information display body while overlapping the scenery.

In this observation optical system, the display light beam 165 emitted from the display image on the information display body 161 is reflected on the surface 162, goes to the object side, and enters the concave half mirror surface 163. After being reflected by the half mirror surface 163, the display light beam 165 becomes a substantially parallel light beam due to the refracting power of the concave surface 163, and after being refracted and transmitted through the surface 162, an enlarged virtual image of the display image is formed. The light is incident on the pupil 164, and the displayed image is recognized by the observer.

On the other hand, the object light beam 166 from the object is reflected by the reflection surface 16.
The light enters a surface 167 substantially parallel to 2 and is refracted to reach a concave half mirror surface 163. A semi-transmissive film is deposited on the concave surface 163, and a part of the object light beam 166 transmits through the concave surface 163 and
After being refracted and transmitted through 2, the light enters the pupil 164 of the viewer. Thus, the observer visually recognizes the display image in the outside scenery while overlapping.

FIG. 17 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 is also an optical system for observing an external scenery and observing a display image displayed on an information display body in an overlapping manner.

In this observation optical system, the display light beam 174 emitted from the information display 170 is applied to the plane 17 forming the prism Pa.
7, and enters the prism Pa and enters the parabolic reflection surface 171. The display light beam 174 is reflected by the reflection surface 171 to become a convergent light beam and forms an image on the focal plane 176. At this time, the reflection surface 171
The display light beam 174 reflected by the light beam 174 constitutes the prism Pa
The light reaches the focal plane 176 while being totally reflected between the two parallel planes 177 and 178, thereby achieving a reduction in the thickness of the entire optical system.

Next, the display light beam 174 emitted as divergent light from the focal plane 176 is incident on a parabolic half mirror 172 while being totally reflected between the planes 177 and 178, and reflected by the half mirror plane 172. Simultaneously, the refracting power forms an enlarged virtual image of the display image and forms a substantially parallel light flux, passes through the surface 177 and enters the observer's pupil 173,
This allows the viewer to recognize the display image.

On the other hand, the object light beam 175 from the outside
The light passes through the surface 178b constituting Pb, passes through the parabolic half mirror 172, passes through the surface 177, and enters the pupil 173 of the observer. The observer visually recognizes the displayed image in an overlapping manner in the outside scenery.

[0036]

In a conventional optical prism having a reflecting surface with a curvature, as in a pentagonal roof prism, an irregularly incident light, which is incident on the prism from a position and an angle other than an effective ray, is used. Harmful ghosts may occur.

Further, the metal film applied to the reflection surface has a high possibility of being corroded under environmental conditions such as high temperature and high humidity.
It is important to ensure the durability of the metal film.

Further, when the prism is made of glass, the material itself such as burns has a problem of environmental resistance.

The above-mentioned conventional observation optical system includes an optical prism having a reflecting surface having a curvature as a constituent element. In these, however, protection of a reflecting film, environmental resistance of a material, and harmfulness caused by improper external light incidence are included. It does not directly disclose techniques for reducing ghost and flare.

According to the present invention, a refracting surface on which a light beam enters, a plurality of reflecting surfaces having a curvature, a refracting surface for emitting the light beam reflected by the plurality of reflecting surfaces, and a plurality of side surfaces are provided on the surface of the transparent body. By covering at least one surface of the optical element with a light-shielding protective member, it is possible to effectively reduce the ghost and flare caused by unnecessary light incident by protecting the optical element from environmental damage and protecting the reflective film. And an optical system using the same.

(1-1) The reflective film is protected by forming a protective member on the reflective film. (1-2) By integrally covering at least two surfaces with a light-shielding protection member, the light-shielding and protection effects at the boundary between the surfaces are not reduced. (1-3) By forming a light-shielding protective member on the side surface, ghost and flare light is effectively reduced and corrosion of the side surface is prevented. (1-4) A single light-shielding sheet-like protective member is adhered to a plurality of surfaces to effectively protect the surfaces with a small number of components. It is an object of the present invention to provide an optical element having at least one effect, and an optical system using the same.

[0042]

The optical element of the present invention comprises: (2-1) a refracting surface on which a light beam is incident on the surface of a transparent body;
In an optical element in which a plurality of reflecting surfaces having a curvature, a refracting surface that emits a light beam reflected by the plurality of reflecting surfaces, and a plurality of side surfaces are integrally formed, at least one of the reflecting surface and the side surface is provided. Cover the surface with a protective member. (2-2) A refracting surface on which a light beam enters, a plurality of reflecting surfaces having a curvature, a refracting surface for emitting the light beam reflected by the plurality of reflecting surfaces, and a plurality of side surfaces, on the surface of the transparent body. Are integrally formed, and at least two adjacent surfaces of the plurality of reflection surfaces and side surfaces are integrally covered with a protective member. It is characterized by

In particular, (2-2-1) the protective member blocks external light rays. (2-2-2) The protective members were formed by spray coating on the surfaces covered by the respective protective members. (2-2-3) The protective members were formed by printing on the surfaces covered by the respective protective members. (2-2-4) The protection member is configured as a sheet-like member, and the protection member is adhered to the surface of the surface covered by the protection member. (2-2-5) The protective member was formed by immersing the optical element in a paint. (2-2-6) The protective member was formed by vapor deposition. (2-2-7) In the refraction surface on which the light beam enters and / or the refraction surface on which the light beam exits, the protection member is formed outside the effective ray part. It is characterized by

Furthermore, the optical element of the present invention is characterized in that (2-3) two rotationally symmetric refracting surfaces and at least three reflecting surfaces each having a curvature are formed on the surface of the transparent body so that the light flux is one refraction. When the light is incident from a surface, the light beam is sequentially reflected by the plurality of reflection surfaces, and then emitted from the other refraction surface to form an image, and the plurality of reflection surfaces having the curvature are all common. At least one of the plurality of side surfaces which are symmetric with respect to one plane and do not have an optical effect on the plurality of reflection surfaces is covered with a protective member. (2-4) A refracting surface on which a light beam enters the surface of the transparent body, a plurality of reflecting surfaces having a curvature, a refracting surface for emitting the light beam reflected by the plurality of reflecting surfaces, and a plurality of side surfaces are integrated. In an optical element having a plane including a reference axis incident on at least one of the reflection surfaces and a reference axis exiting from the optical element, at least one of the reflection surface and the side surface is covered with a protective member. (2-5) The refraction surface on which the light beam enters the surface of the transparent body, the plurality of reflection surfaces having a curvature, the refraction surface for emitting the light beam reflected by the plurality of reflection surfaces, and the plurality of side surfaces are integrated. And an optical element having a plane including a reference axis incident on at least one of the reflection surfaces and a reference axis emerging from the reflection surface, wherein at least two adjacent surfaces of the plurality of reflection surfaces and side surfaces are integrally formed. Cover with a protective member. It is characterized by

In the optical system of the present invention, (2-6) the optical element described in any one of the items (2-1) to (2-5) is used. (2-7) A plurality of the optical elements described in any one of the items (2-1) to (2-5) are combined. It is characterized by

[0046]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The optical element of the present invention and an optical system using the same do not have a symmetry axis such as an optical axis in an ordinary optical system. Therefore, in the optical system of the present invention, a "reference axis" corresponding to the optical axis of the coaxial system is set, and the configuration of various elements in the optical system is described based on the reference axis.

First, the definition of the reference axis will be described. Generally, the optical path of a certain light beam having a reference wavelength from the object plane to the image plane is defined as a "reference axis" in the optical system. Since this does not determine the reference ray, the reference axis ray is usually set according to one of the following two principles. (1) In the case where an axis having a symmetry exists even in a part of the optical system and the aberration can be collected with good symmetry, a ray passing on the axis having the symmetry is set as a reference axis ray. (2) When the symmetry axis does not generally exist in the optical system, or when the aberration cannot be collected with good symmetry even if the symmetry axis partially exists, the center of the object plane (the object to be imaged and the observation range) From the center of the optical system, passes through the optical system in the order of the designated surface of the optical system, passes through the center of the stop in the optical system, or passes through the center of the stop in the optical system to reach the center of the final image plane. A reference axis ray is set, and the optical path is set as a reference axis.

The reference axis defined in this way generally has a bent shape. The reference axis can be handled in the same manner as the optical axis when viewed from outside the optical system. Then, in each surface, the intersection of each surface and the reference axis light beam is set as a reference point of each surface, and the reference axis light beam on the object side of each surface is the incident reference axis,
The reference axis ray on the image side is set as the emission reference axis. Further, the reference axis has a direction (direction), and the direction is a direction in which the reference axis light beam travels during imaging. Therefore, there are an incident reference axis direction and an exit reference axis direction on the incident and exit sides, respectively. In this way, the reference axis finally reaches the image plane while changing its direction along the set order of each surface according to the law of refraction or reflection. In an optical element (optical system) composed of a plurality of surfaces, a reference axis ray incident on the most object side surface is emitted from the incident reference axis of this optical element (optical system) and the most image side surface. The reference axis light to be used is defined as the emission reference axis of this optical element (optical system). or,
The definition of the directions of these incident / exit reference axes is the same as that of the plane.

Before starting the description of the embodiment, a description will be given of how to represent the configuration of the embodiment and common matters of the entire embodiment.

FIG. 11 is an explanatory diagram of a coordinate system that defines the configuration data of the optical system according to the present invention. In the embodiment of the present invention, the i-th surface is defined as the i-th surface along one light beam (shown by a dashed line in FIG. 11 and referred to as a reference axis light beam) traveling from the object side to the image plane.

In FIG. 11, the first surface R1 is a stop, the second surface R2 is a refracting surface coaxial with the first surface, the third surface R3 is a reflecting surface tilted with respect to the second surface R2, and the fourth surface R4. , The fifth surface R5 is a reflecting surface shifted and tilted with respect to each front surface, and the sixth surface R6 is a fifth surface.
This is a refraction surface shifted and tilted with respect to R5. Second side
Each surface from R2 to the sixth surface R6 is formed on one optical element made of a medium such as glass or plastic, and is referred to as a first optical element B1 in FIG.

Therefore, in the configuration of FIG. 11, the medium from the object surface (not shown) to the second surface R2 is air, the medium from the second surface R2 to the sixth surface R6 is a certain common medium, and the medium from the sixth surface R6 to the second surface R6 is not shown. The medium up to the seventh surface R7 is composed of air.

Since the optical system of the present invention is a decentered optical system, each surface constituting the optical system does not have a common optical axis. Therefore, in the embodiment of the present invention, an absolute coordinate system having the origin at the center of the effective beam diameter of the first surface as the stop is set. In the present invention, each axis of the absolute coordinate system is determined as follows.

Z axis: Reference axis passing through the origin toward the second surface R2 Y axis: Straight line passing through the origin and forming 90 ° counterclockwise with respect to the Z axis in the tilt plane (in the paper of FIG. 11) : Straight lines passing through the origin and perpendicular to each of the Z and Y axes (straight lines perpendicular to the plane of FIG. 11) Note that all tilt surfaces constituting the embodiment of the optical element of the present invention basically tilt within the same plane. ing. That is, the reference axis in the optical element is basically in one plane.

In order to express the surface shape of the i-th surface constituting the optical system, the shape of the surface is expressed in an absolute coordinate system.
Since it is easier to understand the shape by recognizing the shape by setting a local coordinate system whose origin is the reference point where the reference axis intersects with the i-th surface and expressing the surface shape in the local coordinate system, the present invention In the numerical data of the embodiment, the surface shape of the i-th surface is represented by a local coordinate system.

The tilt angle of the i-th surface in the YZ plane is an angle θ with the counterclockwise direction being positive with respect to the Z axis of the absolute coordinate system.
i (unit: °). 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 tilt or shift of the plane in the XZ and XY planes. Further, the y, z axes of the local coordinates (x, y, z) of the i-th plane are inclined at an angle θi in the YZ plane with respect to the absolute coordinate system (X, Y, Z). Set as follows.

Z-axis: an angle θ that passes through the origin of the local coordinate system and is counterclockwise in the YZ plane with respect to the Z direction of the absolute coordinate system.
i-axis straight line y-axis: straight line passing through the origin of local coordinates and making 90 ° counterclockwise in the YZ plane with respect to z-direction x-axis: straight line passing through the origin of local coordinates and perpendicular to the YZ plane Di is a scalar representing the distance between the origins of the local coordinates of the i-th surface and the (i + 1) -th surface, and Ndi and νdi are the i-th surface and the (i +
1) The refractive index and Abbe number of the medium between surfaces. The aperture and the final image plane are also shown as one plane.

The embodiment of the present invention has a spherical surface and a rotationally asymmetric aspheric surface. Spherical portion of which I wrote the radius of curvature R _i as a spherical shape. The sign of the radius of curvature R _i is
The case where the center of curvature is in the plus direction of the local coordinate on the z axis is defined as plus, and the case where the center of curvature is in the minus direction of the z axis is defined as minus.

Here, the spherical surface has a shape represented by the following equation.

[0060]

(Equation 1) Further, the optical system of the present invention has at least one or more rotationally asymmetric aspheric surfaces, and the shape is represented by the following equation.

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 ], and z = A / B + C ₀₂ y ² + C ₁₁ xy + C ₂₀ x ² + C ₀₃ y ³ + C ₁₂ xy ² + C
₂₁ x ² y + C ₃₀ x ³ + C ₀₄ y ⁴ + C ₁₃ xy ³ + C ₂₂ x ² y ² + C ₃₁ x ³ y + C
₄₀ x ⁴ + ····························· In the numerical examples of the present invention, the shape of each rotationally asymmetric surface is a plane-based aspheric surface where a = b = ∞ and t = 0 in the above-mentioned curved surface equation. , X using only the even-order terms with respect to x and making the odd-order terms zero, yz
The plane has a plane-symmetrical shape with a plane of symmetry. Further, when the following condition is satisfied, the shape is symmetric with respect to the xz plane.

[0062] If the C ₀₃ = C ₂₁ = 0 Further _{C 02 = C 20 C 04 =} C 40 = C 22/2 is satisfied represents a rotation-symmetrical shape. If the above conditions are not satisfied, the shape is non-rotationally symmetric.

In the embodiment of the optical system of the present invention, as shown in FIG. 11, the first surface is a stop. The horizontal half angle of view u _Y is the maximum angle of view of the light beam incident on the aperture stop R1 in the YZ plane in FIG. 11, and the vertical half angle of view u _X is the aperture angle in the XZ plane.
This is the maximum angle of view of the light beam incident on R1. Also, the diameter of the stop R1 as the first surface is shown as the stop diameter. This is related to the brightness of the optical system. Since the entrance pupil is located on the first surface, the aperture diameter is equal to the entrance pupil diameter.

The effective image area on the image plane is shown as an image size. The image size is represented by a rectangular area in which the size in the y direction of the local coordinates is horizontal and the size in the x direction is vertical.

FIG. 1 is a sectional view of an embodiment of the optical system of the present invention. The figure also shows the optical path. In FIG. 1, B1
Is an optical element having a plurality of curved reflecting surfaces, which is made of a transparent material such as glass. On the surface of the optical element B1, a plane (incident surface) R2 and a concave mirror R3
Five reflecting surfaces of a reflecting surface R4, a concave mirror R5, a reflecting surface R6, and a concave mirror R7 and a concave refracting surface (exit surface) R8 are formed. R1 is a stop (entrance pupil) arranged on the object side of the optical element B1. or,
R9 is the final image plane, and the image sensor (imaging medium) such as CCD
Are located. 1 is the reference axis of the optical system.

Each of the two refraction surfaces is a rotationally symmetric spherical surface or plane. This is for satisfying the condition of chromatic aberration correction and for accurately measuring the reference axis when manufacturing and evaluating the optical system. Further, by making the refraction surface rotationally symmetric, it is possible to reduce the occurrence of asymmetric chromatic aberration. All the reflecting surfaces are surfaces symmetric with respect to the YZ plane.

Next, the image forming operation in this embodiment will be described. The light flux from the object is incident on the incident surface R2 of the optical element B1 after the amount of incident light is regulated by the aperture stop R1, is reflected by the surface R3, and forms an image once between the surfaces R3 and R4, and then Faces R4, R5,
The light is successively reflected by R6 and R7, emitted from the exit surface R8, and re-imaged on the final image formation surface R9.

As described above, the light beam incident from the surface R2 is
An intermediate image is formed inside, but this is to make the optical system thin in the X direction. The off-axis chief ray that has exited the stop R1 converges without widening, and the first reflection due to the wide angle of the optical system. The increase in effective diameter of each surface after surface R3 is suppressed.

In the present embodiment, the incident reference axis, the emission reference axis, and the reference axis in the optical element B1 are all on the plane of the paper (YZ plane).

As described above, the optical element B1 has a desired optical performance due to the entrance and exit surfaces and the plurality of curved reflecting mirrors therein, and functions as a plate-shaped / thin lens unit having an image forming function as a whole. ing.

Each of the reflecting surfaces constituting the optical element B1 is a so-called eccentric reflecting surface in which the normal line at the intersection (reference point) between the reference axis for entering and exiting and the reflecting surface does not coincide with the direction of the reference axis.
This prevents vignetting that occurs in the conventional coaxial mirror optical system, and allows more free arrangement of each surface, thereby achieving space-efficient, compact and variously shaped optical elements. Can be.

Further, the shape of each reflecting surface is two orthogonal surfaces.
This is a plane having only one symmetric plane having different refractive powers within (yz plane and xz plane). This is to suppress eccentric aberration caused by eccentric arrangement of each reflecting surface.

FIGS. 2 and 3 show an embodiment of the optical element of the present invention.
1 is a perspective view of FIG. The optical element of this embodiment is used for the optical system shown in FIG. In the drawings, the same reference numerals as those in FIG. 1 indicate the same elements. In the figure, 2, 3, 4, 5, and 6 are reflection surfaces R, respectively.
4, protection members formed over R6, R7, R5, R3. In addition, a metal reflective film is formed by vapor deposition or the like on an effective portion of the surface R3, R4, R5, R6, and R7 (portions indicated by dots in the figure), and each protective member is formed on the metal reflective film. Has formed.

The metal reflective film formed on the surface of each reflective surface has a high reflectance to improve the transmittance in the entire optical element system.

However, there is a high possibility that the deposited metal reflection film is corroded in environmental conditions such as high temperature and high humidity. Therefore, in the present embodiment, in order to ensure the durability of the metal reflection film, the protection member is formed on the entire surface of each reflection surface from above the metal reflection film. Protective members 2, 3, 4, 5, 6
Protects the metal reflective film by shielding it from air.

Each reflecting surface is formed by depositing a metal reflecting film only on the effective portion thereof, thereby improving the imaging performance by preventing extra reflection. However, if the protective member is transparent, external light enters the optical element from the part without a metal reflective film on each reflective surface (for example, part a in FIG. 1), causing new ghost and flare. Become. Therefore, external light is blocked by forming a light-shielding protective member over the entire reflecting surface.

By the way, in the optical element B1, the surface R2 and the surface
R4, surface R3, surface R5, and surface R7 are adjacent. Therefore, protection members for adjacent reflection surfaces, that is, protection members 2-3 and protection member 4
2 to 6 are preferably formed integrally as shown in FIGS.

As a method of forming the protective member, for example, blackening, which has been conventionally used as a light shielding means of an optical system, may be performed continuously on adjacent surfaces.

FIG. 4 is a perspective view of Embodiment 2 of the optical element of the present invention. The optical element of this embodiment is used for the optical system shown in FIG. In the present embodiment, the surfaces that do not perform optical functions such as reflection and refraction of the first embodiment of the optical element (for example, the surfaces 13 and 17 in FIG. 2) are used.
Etc.) on which a light-shielding protective member is formed.

There is a sufficient possibility that external light may enter from a surface of the optical element which does not perform optical functions such as reflection and refraction.

Further, when the optical element is formed of a material such as glass, there is a possibility that the material itself such as burns may be corroded on its surface.

Therefore, in the present embodiment, a light-shielding protective member is formed integrally on the two side surfaces, left and right end surfaces (one side not shown) integrally with the protective member on the reflective surface to prevent the penetration and corrosion of external light.

Further, it is desirable to form a light-shielding protection member integrally with the protection member on the reflection surface also in a region outside the effective portion of the incident surface and the emission surface.

FIG. 5 is a perspective view of Embodiment 3 of the optical element of the present invention. In the present embodiment, light-shielding protection members indicated by 9 and 10 are provided on the periphery (outside the effective portion) of the entrance surface R2 and the exit surface R8, respectively, so that light enters the prism from a position and angle other than the effective light beam. Harmful ghost light due to illegal incident light is effectively cut.

FIG. 6 shows an example of ghost light. For example,
The light beam 11 obliquely incident on the stop is reflected by the upper surface 12 and the lower surface 13 of the prism, exits from the exit surface R8, and reaches the image surface R9. Since this ray 11 does not naturally pass through the regular optical path, it becomes a ghost. Even if the upper surface 12 is roughened to be a diffusing surface, the light scattered from the upper surface 12 always reaches the image plane, which again causes flare.

Therefore, in this embodiment, light is prevented from reaching the upper side surface 12 by arranging the light-shielding protective member 9 around the incident surface R2 as shown in FIG. 5, so that the cause of the ghost flare can be effectively reduced. Can be removed.

By disposing the light shielding member 10 also on the exit surface R8, ghost and flare light reaching the image plane can be effectively cut.

It is desirable that the protection members 2, 3, 9, 10 be formed integrally.

The light shielding members 9 and 10 have openings for passing regular light rays. The shapes of the openings provided in the light shielding members 9 and 10 are substantially the same as the shapes of the effective ray portions on the entrance surface and the exit surface, but the actual shape of the effective ray portions is a spot diagram of each surface shown in FIG. As you can see, it is not necessarily circular. Therefore, the shape of the opening may be a circle or an ellipse sufficiently including the light beam effective portion, but it is more preferable to match the shape of the light beam effective portion.

As described above, each surface constituting the optical element,
It is preferable that at least two adjacent protective members of the (incident surface / exit surface / each reflecting surface / other surface not contributing to the image forming action) are integrally formed. In this manner, light is completely shielded particularly at the joint between the reflective surfaces where the light shielding / protecting members tend to be discontinuous or between surfaces that intersect at right angles.

When these light-shielding members are provided as separate components as described later, the number of components can be reduced.

FIG. 8 is a perspective view of Embodiment 4 of the optical element of the present invention. In this embodiment, the protection members formed in the previous embodiments are all integrally formed.

That is, in the optical element B1 of the present embodiment, the light-shielding protective member 14 is integrally formed on the entrance surface, the exit surface, each reflection surface, and other surfaces.

In this manner, it is possible to almost completely improve the environmental resistance of the optical element B1 and reduce ghost and flare due to unnecessary light.

The protective member 14 can be formed by covering a necessary opening in advance and spraying a black paint or dipping the paint in the paint.

Further, since the entire optical element can be formed in a substantially sealed structure, further improvement in environmental resistance can be expected.

As a method of forming the protective member, in addition to the above-described black coating and paint immersion, a light-shielding protective member is formed by vapor deposition used for a conventional antireflection film, or directly printed on the surface of an optical element. Is also effective.

In particular, in the formation of the protective member by the printing method, in addition to the conventional offset printing and the like, the formation of the protective member by the inkjet method printing that can easily perform precise printing has a complicated curved surface shape of the present invention. It is effective for devices.

FIG. 9 and FIG. 10 are explanatory perspective views of Embodiment 5 of the optical element of the present invention. In the present embodiment, a light-shielding protective member is formed by closely attaching a sheet-shaped protective member having an appropriate shape and having a light-shielding property to a plurality of surfaces of an optical element.

In this embodiment, the entrance surface R2 and the exit surface
The protection member of R8 and the reflection surfaces R4 and R6 are integrated to form a sheet-like light-shielding protection member 15, and the protection member 15 is effectively and easily protected and light-shielded by bringing the protection member 15 into close contact with the optical element B1. It is carried out.

Further, as shown in FIG. 10, the reflecting surfaces R3, R5, R7
Sheet-like light-shielding protection member 16
In this way, these surfaces are effectively and simply protected and shielded from light by being in close contact with the optical element B1.

In the embodiment of the optical system of the present invention, 1
Although the photographing optical system using one optical element has been described as an example, the observation optical system or the optical system using a plurality of such optical elements may be configured as described above with respect to each optical element. As a result, it is possible to improve environmental resistance and reduce ghost and flare light.

Next, numerical data in the embodiment of the optical system of the present invention shown in FIG. 1 is shown below. [Numerical data] Horizontal half angle of view 20.0 Vertical half angle of view 15.3 Aperture diameter 2.40 Image size 4 mm horizontally x 3 mm vertically 1 Yi Zi θi Di Ndi νdi 1 0.00 0.00 0.00 4.00 1 Aperture 2 0.00 4.00 0.00 8.00 1.51633 64.15 Refractive surface 3 0.00 12.00 18.00 9.72 1.51633 64.15 Reflective surface 4 -5.71 4.14 3.00 9.33 1.51633 64.15 Reflective surface 5 -10.38 12.22 -10.00 8.84 1.51633 64.15 Reflective surface 6 -11.91 3.52 -18.00 8.91 1.51633 64.15 Reflective surface 7 -18.32 9.70 -23.00 6.98 1.51633 64.15 8 -18.32 2.73 0.00 8.06 1 Refraction surface 9 -18.32 -5.33 0.00 0.00 1 Image surface Spherical shape R2 surface R ₂ = ∞ R8 surface R ₈ = -10.952 Aspheric surface shape R3 surface C ₀₂ = -3.07038e-02 C ₂₀ =- 3.87628e-02 C ₀₃ = 1.83660e-04 C ₂₁ = -2.47678e-04 C ₀₄ = 1.82085e-05 C ₂₂ = -1.81479e-05 C ₄₀ = -9.91286e-06 R4 side C ₀₂ = -1.46712e -02 C ₂₀ = -8.04832e-02 C ₀₃ = 1.82943e-03 C ₂₁ = -2.88424e-03 C ₀₄ = 7.71058e-05 C ₂₂ = -8.94316e-04 C ₄₀ = -7.74679e-04 R5 surface C ₀₂ = -1.54524e-02 C ₂₀ = -3.21031e-02 C ₀₃ = 6.71883e-04 C ₂₁ = -6.30965e-04 C ₀₄ = -4.48412e-05 C ₂₂ = -7.00525e-05 C ₄₀ = -5.65456e-05 R6 surface C ₀₂ = -3.51167e-03 C ₂₀ = -1.84016e-02 C ₀₃ = 3.35568e-04 C ₂₁ = -3.04934e-03 C ₀₄ = -1.52491e-04 C ₂₂ = -2.38033e-04 C ₄₀ = -1.93476e-04 R7 surface C ₀₂ = -2.08695e-02 C ₂₀ = -2.26946e-02 C ₀₃ = 9.05991e-05 C ₂₁ = -1.04282e-03 C ₀₄ =- 4.51664e-05 C ₂₂ = -3.44033e-05 C ₄₀ = -3.07678e-05

[0104]

According to the present invention, a refracting surface on which a light beam is incident, a plurality of reflecting surfaces having a curvature, and a refraction for emitting the light beam reflected by the plurality of reflecting surfaces are provided. By covering at least one surface with a light-shielding protective member in an optical element in which a surface and a plurality of side surfaces are integrally molded, ghost and flare due to environmental resistance of the optical element, protection of the reflective film, and incidence of unnecessary light An optical element that effectively reduces light and an optical system using the same are achieved.

(3-1) Protecting the reflective film by forming a protective member on the reflective film. (3-2) By integrally covering at least two surfaces with a light-shielding protection member, the light-shielding and protection effects at the boundary between the surfaces are not reduced. (3-3) By forming a light-shielding protective member on the side surface, ghost and flare light is effectively reduced and corrosion of the side surface is prevented. (3-4) A single light-shielding sheet-like protective member is adhered to a plurality of surfaces to effectively protect the surfaces with a small number of components. Optical element having at least one effect and an optical system using the same are achieved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an embodiment of the optical system of the present invention.

FIG. 2 is a perspective view of Embodiment 1 of the optical element of the present invention.

FIG. 3 is a perspective view of Embodiment 1 of the optical element of the present invention.

FIG. 4 is a perspective view of Embodiment 2 of the optical element of the present invention.

FIG. 5 is a perspective view of Embodiment 3 of the optical element of the present invention.

FIG. 6 is an explanatory diagram of an example of ghost light.

FIG. 7 is a spot diagram of each surface of the optical element.

FIG. 8 is a perspective view of Embodiment 4 of the optical element of the present invention.

FIG. 9 is a perspective view of Embodiment 5 of the optical element of the present invention.

FIG. 10 is a perspective view of Embodiment 5 of the optical element of the present invention.

FIG. 11 is an explanatory diagram of a coordinate system defining configuration data of the optical system according to the present invention.

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

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

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

FIG. 15 is an explanatory view of a conventional optical prism.

FIG. 16 is a schematic view of a main part of a conventional observation optical system.

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

[Explanation of symbols]

 B1 Optical element R1 Aperture R2 Incident surface R3, R4, R5, R6, R7 Reflective surface R8 Exit surface R9 Final image plane 1 Reference axis 2, 3, 4, 5, 6, 7, 8, 9, 10, 14, 14, 15, 16 Protective member 11 Ghost light 12 Upper side 13 Lower side 17 Side

Claims (14)

[Claims] 1. A refracting surface on which a light beam enters a surface of a transparent body, a plurality of reflecting surfaces having a curvature, a refracting surface for emitting a light beam reflected by the plurality of reflecting surfaces, and a plurality of side surfaces. An optical element integrally formed, wherein at least one of the reflection surface and the side surface is covered with a protective member. 2. A refracting surface on which a light beam enters, a plurality of reflecting surfaces having a curvature, a refracting surface for emitting a light beam reflected by the plurality of reflecting surfaces, and a plurality of side surfaces, on a surface of the transparent body. An optical element, wherein at least two adjacent surfaces of the plurality of reflection surfaces and side surfaces are integrally covered with a protective member. 3. The optical element according to claim 1, wherein the protection member blocks external light rays. 4. The method according to claim 1, wherein said protective members are formed by spray painting on surfaces of surfaces covered by said protective members.
The optical element according to any one of claims 3 to 3. 5. The optical element according to claim 1, wherein the protective member is formed by printing on a surface of a surface covered by each of the protective members. 6. The optical device according to claim 1, wherein the protection member is formed as a sheet-shaped member, and the protection member is brought into close contact with a surface covered by the protection member. element. 7. The protective member is formed by immersing the optical element in a paint.
4. The optical element according to any one of 3. 8. The optical element according to claim 1, wherein said protection member is formed by vapor deposition. 9. The protection member is formed outside a beam effective portion on a refraction surface on which the light beam enters and / or a refraction surface on which the light beam exits.
An optical element according to any one of claims 1 to 8. 10. A transparent body having two rotationally symmetric refraction surfaces and at least three reflection surfaces each having a curvature. When a light beam enters from one refraction surface, the light beam is transmitted to the plurality of reflection surfaces. In an optical element that forms an image by sequentially reflecting on a reflecting surface and then emitting from the other refracting surface, the plurality of reflecting surfaces having the curvature are all symmetric with respect to a common plane, and An optical element, wherein at least one of a plurality of side surfaces which do not have an optical function with a reflection surface is covered with a protective member. 11. A refracting surface on which a light beam enters a surface of a transparent body, a plurality of reflecting surfaces having a curvature, a refracting surface for emitting a light beam reflected by the plurality of reflecting surfaces, and a plurality of side surfaces are integrated. And an optical element having a plane including a reference axis incident on at least one of the reflection surfaces and a reference axis emerging from the reflection surface, wherein at least one of the reflection surface and the side surface is covered with a protective member. Optical element. 12. A refracting surface on which a light beam is incident on a surface of a transparent body, a plurality of reflecting surfaces having a curvature, a refracting surface for emitting a light beam reflected by the plurality of reflecting surfaces, and a plurality of side surfaces. And an optical element having a plane including a reference axis incident on at least one of the reflection surfaces and a reference axis emerging from the reflection surface, wherein at least two adjacent surfaces of the plurality of reflection surfaces and side surfaces are integrally formed. An optical element characterized by being covered with a protective member. 13. An optical system using the optical element according to claim 1. Description: 14. An optical system comprising a combination of a plurality of the optical elements according to claim 1. Description: