JP2002350730A - Image formation optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image formation optical system which has an excellent image formation performance even when a first mirror has a poor accuracy. SOLUTION: In the image formation optical system 20, which is provided with a large elliptic face mirror 23 (a first mirror) having an incident pupil 29, a hyperbolic face mirror 24 (a second mirror), a flat reflection mirror 25 which deflects light and does not contribute to an image formation, a condensing optical system 21 having a small elliptic mirror 26 (a third mirror), and an image detector 27 on which an image is formed with the condensing optical system 21, an exit pupil 30 is smaller than an incident pupil 29, and a correction optical element 22 arranged in the vicinity of an exit pupil 30 and the image detector 27 are provided, thus aberration is corrected with the exit pupil 30 which reflects the incident pupil 29 by means of a correction optical element 22, and the aberration is easily corrected at low cost with the small optical element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical apparatus such as a reflection type telescope.

[0002]

2. Description of the Related Art FIG. 18 is a schematic diagram showing a configuration of a conventional imaging optical system. In FIG. 18, the imaging optical system 1 includes a condensing optical system 6 for collecting light. This condensing optical system 6
A large ellipsoidal mirror 2 which is a first mirror on which light from an object to be imaged, which is a set of object points, and a light reflected by the large ellipsoidal mirror 2 on an optical axis are reflected to form an imaging point 10 once. , A plane mirror 4 for changing the direction of light reflected by the plane mirror 3 to make the imaging optical system 1 compact, and a plane mirror A small ellipsoidal mirror 5, which is a third mirror that reflects the light reflected by 4 and forms the image point 11 again, is provided. Further, an image detector 7 is arranged at an image forming point of the light reflected by the small ellipsoidal mirror 5, and an image at this image forming point is converted into an electric signal or the like and subjected to signal processing. Note that the image detector 7 may be human eyes.

The large ellipsoidal mirror 2 has an aperture stop for limiting an area through which light passes through the focusing optical system 6. Of the light limited by the aperture stop, light whose light from any one object point of the imaging target is limited is referred to as a light beam. Further, the position of the aperture stop is set at the same time as the entrance pupil 8.
Position. Here, the entrance pupil refers to a virtual image formed by a part of the optical system interposed between the aperture stop and the object side when viewed from the object side. Therefore, there is no optical system involved in forming a virtual image of the aperture stop between the aperture stop of the large ellipsoidal mirror 2 and the object side (the left side of the large ellipsoidal mirror 2 in FIG. 18). 2 has an aperture stop, the position of the entrance pupil 8 of the condensing optical system 6 coincides with the aperture stop of the large ellipsoidal mirror 2.

[0004] Since the plane reflecting mirror 4 is arranged merely for changing the direction of the light beam, it does not contribute to the image formation on the image detector 7.

[0005] The hyperboloid mirror 3 reflects the light beam reflected within the aperture stop of the large ellipsoidal mirror 2, that is, the entrance pupil 8 on the outer surface, and increases the focal length to increase the spatial resolution. In FIG. 18, an image point 10 is formed between the hyperboloid mirror 3 and the plane reflecting mirror 4. An exit pupil 9 is formed on the image side by the hyperboloid mirror 3 and the small ellipsoidal mirror 5, and a detection image point 11 is formed on the image detector 7 behind the exit pupil 9. Here, the exit pupil is a part of the optical system interposed between the aperture stop and the image side when viewed from the image side (here, the hyperboloid mirror 3 and the small elliptical mirror 5).
A virtual image of the aperture stop created by Accordingly, since the position of the aperture stop of the condenser optical system 6 coincides with the entrance pupil 8, the exit pupil 9 of the condenser optical system 6 is consequently the hyperboloid mirror 3 and the small pupil 3 when viewed from the image side. This is a virtual image of the entrance pupil 8 by the elliptical mirror 5.

When light from one object point of an object to be imaged enters such an image forming optical system 1, the light is converted into a large elliptical mirror 2.
Is reflected as a limited ray bundle within the aperture stop which coincides with the entrance pupil 8 of the first lens, and this ray bundle is reflected by the hyperboloid mirror 3 and forms an image before reaching the plane reflecting mirror 4. Thereafter, the light beam is reflected by the plane reflecting mirror 4, changes its direction, and is reflected by the small elliptical mirror 5. This operation is the same for light from object points of all the imaging targets. The light beam reflected by the small ellipsoidal mirror 5 forms an image at the detection image forming point 11 on the image detector 7, and all the light beams are common between the small ellipsoidal mirror 5 and the detection image forming point 11. Exit pupil 9 is formed.

In this imaging optical system 1, a combination of a large elliptical mirror 2 as a first mirror, a hyperboloid mirror 3 as a second mirror, and a small elliptical mirror 5 as a third mirror, for example, has a diameter of 1.5 m. A large viewing angle of 1.5 for a reflective optical system
Good imaging performance is obtained in the range of °.

[0008]

However, such a conventional imaging optical system 1 has the following problems. That is, by combining the large ellipsoidal mirror 2, the hyperboloidal mirror 3, and the small ellipsoidal mirror 5 related to imaging, the aberration of the imaging optical system 1 is corrected as a whole, and high imaging performance is obtained. For this reason, unless these three reflecting mirrors 2, 3 and 5 are manufactured precisely as designed, aberrations are greater than designed. In particular, since the large ellipsoidal mirror 2 is manufactured to be large in order to collect a large amount of light, there has been a problem that it takes a long time to manufacture the mirror and the cost is high.

In order to correct the aberration, the reflecting mirror 2,
It is necessary to remanufacture 3 and 5 themselves, and there is also a problem that it is difficult to correct the aberration and the cost is high.

Accordingly, an object of the present invention is to solve the above-mentioned problems, and to provide an imaging optical system which has high imaging performance, can be manufactured at low cost, and can easily correct aberrations. The purpose is to:

[0011]

An imaging optical system according to the present invention is arranged near the exit pupil in an imaging optical system having a condensing optical system having an exit pupil smaller than the entrance pupil on the image side, A correction optical element for correcting the aberration of the condensing optical system.

Further, all of the condensing optical systems are reflecting mirrors.

[0013] The condensing optical system includes a first mirror having at least the entrance pupil.

The first mirror is an elliptical mirror.

Further, the first mirror is a spherical mirror.

Further, the first mirror is a parabolic mirror.

The first mirror comprises a plurality of split mirrors.

The reflecting mirror has a reflecting surface whose shape is changed.

Further, the reflecting mirror is provided with an angle control means for changing the incident angle of light by rotating the reflecting mirror.

The correction optical element has a light transmitting body having a refractive index different from that of the surroundings, and the aberration is corrected by the light transmitting body.

In the light transmitting body, a plurality of light transmitting portions having different refractive indices are laminated in close contact with each other.

The plurality of light transmitting bodies are arranged at intervals.

Further, the correction optical element has a light reflector having a reflecting surface, and the aberration is corrected by the light reflector.

Further, the light reflector is in close contact with the light transmitting body whose reflecting surface faces.

In the correction optical element, the shape of the reflection surface changes.

Further, the condensing optical system has aberration measuring means for measuring aberration, and the shape of the reflecting surface changes based on the aberration measured by the aberration measuring means.

The correction optical element is provided with an angle control means for rotating the correction optical element to change the incident angle of light.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below. Members and portions denoted by the same reference numerals are the same or corresponding members and portions. Embodiment 1 FIG. FIG. 1 is a schematic diagram showing a configuration of an imaging optical system according to Embodiment 1 of the present invention. In FIG. 1, an imaging optical system 20 includes a condensing optical system 21 for collecting light from an object to be imaged, and a correction optical element 22 having a reflecting mirror and correcting the aberration of the condensing optical system 21. ing.

The condensing optical system 21 reflects the light reflected by the large ellipsoidal mirror 23 on the optical axis, which is the first mirror on which the light from the object to be imaged enters, and forms the light once. A hyperboloid mirror 24 serving as a second mirror for forming an image point; a plane reflecting mirror 25 for changing the direction of light reflected by the hyperboloid mirror 24 to make the focusing optical system 21 compact; A small elliptical mirror 26, which is a third mirror for reflecting light reflected by the reflecting mirror 25 and forming an image point again, is provided.

The large ellipsoidal mirror 23 has an aperture stop 28, which coincides with the position of the entrance pupil 29 at the same time. Light from one object point of the object to be imaged defined by the aperture stop 28 of the large ellipsoidal mirror 23 is called a light beam, and this light beam is a group of light beams related to image formation. Therefore, an image-forming object, which is a group of object points, is formed on the image side by a light beam from each object point.

The exit pupil 30, which is a virtual image of the aperture stop 28 when viewed from the image side, is smaller than the entrance pupil 29, and this exit pupil 30 is all reflected by the hyperboloid mirror 24 and the small ellipsoid mirror 26. A small ellipsoidal mirror 2 in which the light beam passes through a common position
6 is formed behind. Therefore, it can be said that the exit pupil 30 is a virtual image of the entrance pupil 29 when viewed from the image side formed by the hyperboloid mirror 24 and the small ellipsoid mirror 26.

The correction optical element 22 is a light reflector having a reflection surface 32. The reflecting surface 32 is arranged near the exit pupil 30 and reflects all the light beams reflected by the small ellipsoidal mirror 26. The reflected light beams are imaged at the detection imaging points 31, respectively. The correction optical element 22 has many irregularities on the reflection surface 32 in order to correct the aberration.
In other words, since the aperture stop 28 is located on the large ellipsoidal mirror 23, the entrance pupil 29 coincides with the aperture stop 28, and the virtual image on the image side of the aperture stop 28 is the exit pupil 30. The ray bundle of the exit pupil 30 reflects the ray bundle of the entrance pupil 29, and the cause of aberration caused by the large ellipsoidal mirror 23 can be corrected by the correction optical element 22 at the exit pupil 30. For example, if there is a portion depressed from a predetermined shape in the large ellipsoidal mirror 23, the ray bundle at that portion has a longer distance to reach the reflection surface of the large ellipsoidal mirror 23 and is reflected later than the predetermined reflection. Will do. By providing a raised reflecting surface 32 at a portion of the exit pupil 30 corresponding to the recessed portion of the large ellipsoidal mirror 23 in order to recover this delay, the inherent delay generated by the large ellipsoidal mirror 23 is recovered by recovering the delay. It corrects the aberration.

Accordingly, light from the object point of the object to be imaged which is incident on the large ellipsoidal mirror 23 is reflected by the aperture stop 28 and reflected as a light beam, and this light beam is reflected by the hyperboloid mirror 24 and the plane reflecting mirror 25. And an exit pupil 30 reflected by the small ellipsoidal mirror 26
The aberration is corrected by the correction optical element 22 at the position of and the light is reflected. After that, the light beam whose aberration has been corrected is formed on the image detector 27.

As described above, even if the shape of the large ellipsoidal mirror 23 has some inconvenience, the correction optical element 22 is connected to the entrance pupil 2 of the first mirror.
9 can be corrected by the exit pupil 30 by arranging it on the exit pupil 30 reflecting the number 9, and since the exit pupil 30 is smaller than the entrance pupil 29, the correction optical element 22 is small, easily and It can be manufactured accurately.

Further, since the aberration can be corrected by the correction optical element 22 of the exit pupil 30, the large ellipsoidal mirror 23 can achieve a sufficiently good imaging performance even if the accuracy is not so high. Also, the large elliptical mirror 23 can be manufactured easily and at low cost. Further, even when a defect due to aberration occurs due to, for example, aging, it is only necessary to simply replace the small and inexpensive correction optical element 22, and it is possible to easily cope with the defect of aberration at low cost.

Even if the large ellipsoidal mirror 23 is a spherical mirror, it is possible to know how much the shape of the reflecting surface deviates from the ellipsoidal mirror, and the shape of the correction optical element 22 of the exit pupil 30 corresponds to the spherical mirror. It does not matter if it is manufactured as follows.

Also, the large elliptical mirror 23 may be a parabolic mirror.

Similarly, the large elliptical mirror 23 may be of a deployable type which can be freely opened and closed.

Embodiment 2 FIG. 2 is a schematic diagram showing a schematic configuration of an imaging optical system according to Embodiment 2 of the present invention.
In FIG. 2, a correction optical element 2 such as a servomotor is shown.
An angle control means 40 for changing the angle 2 is provided in the correction optical element 22. In addition, for example, an angle detecting means 41 such as a gyroscope is provided at a location where the imaging of the imaging optical system 20 is not hindered. Other configurations are the same as in the first embodiment.

The angle detecting means 41 constantly monitors whether the direction of the line of sight of the object to be imaged by the image forming optical system 20 is kept constant, and detects the angle when the image forming optical system 20 is inclined and deviates from the line of sight. The means 41 sends a signal to the angle control means 40,
Upon receiving this signal, the angle control means 40
Is changed to return to the normal line-of-sight direction.

With such a configuration, the angle of the correction optical element 22 is automatically corrected even when the direction of the line of sight of the object to be imaged changes due to vibration or shaking of the image forming optical system 20. , An image-forming object can be formed on the image detector 27.

The large ellipsoidal mirror 23, the hyperboloidal mirror 24, the plane reflecting mirror 25 and the small ellipsoidal mirror 26 may be provided with an angle control means 40. Even with such a configuration, each angle control unit 4 is controlled by a signal from the angle detection unit 41.
0 operates to change the angles of the large ellipsoid mirror 23, the hyperboloid mirror 24, the plane reflection mirror 25, and the small ellipsoid mirror 26 so that the imaging optical system 20 returns to the normal line-of-sight direction. Thus, an image forming object in a normal line of sight can be formed on the image detector 27.

Embodiment 3 FIG. 3 is a schematic diagram showing a schematic configuration of an imaging optical system according to Embodiment 3 of the present invention.
In FIG. 3, the correction optical element 50 is an optical element whose shape of the reflection surface changes. FIG. 4 is a sectional perspective view of a part of the correction optical element 50. As shown in FIG. 4, the correction optical element 50 is a flexible silicon film 5 having a reflection surface 51.
2, an electrostatic actuator 53 provided on the back surface of the silicon film 52 and movable by static electricity, and an adhesive rod 54 connecting the silicon film 52 and the electrostatic actuator 53.

The electrostatic actuator 53 has a movable electrode 55 and a fixed electrode 56. The movable electrode 55 is moved by adjusting the generation of static electricity between the two electrodes.
Of the surface (reflection surface 51) of the silicon film 52 connected to the substrate can be adjusted. Such a reflecting mirror that can freely change the unevenness of the reflecting surface is called a deformable mirror.

As shown in FIG. 3, the imaging optical system 20 also includes an aberration measuring means 57 for measuring and transmitting the aberration by, for example, a Shack-Hartmann sensor and the like, and a measurement of the aberration measured by the aberration measuring means 57. A shape control means 5 for controlling by using static electricity so as to receive the result and to make the reflection surface shape of the correction optical element 50 optimum for correcting the aberration.
8 is provided.

With such a configuration, the aberration measuring means 57 such as a Shack-Hartmann sensor measures the aberration, and the result of the measurement is transmitted to the shape control means 58. The shape control means 58 generates static electricity between the movable electrode 55 and the fixed electrode 56 at a specific location so as to correct the aberration based on the measurement result of the aberration. Due to the generation of the static electricity, the silicon film 52 at that location moves, and the correction optical element 5
The unevenness of the 0 reflection surface 51 is formed. Due to the unevenness, the light beam reflected by the reflection surface 51 of the correction optical element 50 is corrected for aberration and formed on the image detector 27.

Accordingly, the assembly and adjustment of the imaging optical system 20 is facilitated, and the accuracy is improved. Also, for aberrations due to changes in state such as temperature and atmospheric pressure, vibration, distortion of the propagation path, aging, etc., the aberration is measured by the aberration measuring means 57, and the shape of the reflecting surface of the correction optical element 22 is determined by the shape control means 58. By adjusting, stable imaging performance can be obtained.

The large ellipsoidal mirror 23, the hyperboloidal mirror 24 and the small ellipsoidal mirror 26 may be deformable mirrors. With such a configuration, the large elliptical mirror 2
3. Since the respective reflecting surfaces of the hyperboloid mirror 24 and the small elliptical mirror 26 are freely deformed, the aberration of the imaging optical system 20 can be corrected by the reflecting mirrors themselves.

Embodiment 4 FIG. 5 is a front view showing the configuration of the first mirror of the imaging optical system according to Embodiment 4 of the present invention, and FIG. 6 is a cross-sectional view taken along the line VI-VI of FIG. 5 and 6, a large elliptical mirror 6 as a first mirror is shown.
0 is composed of a plurality of (for example, four) split mirrors 61. Each of the split mirrors 61 is a part forming the large elliptical mirror 60, and the shape of the reflection surface is the same as the shape of each divided portion when the designed large elliptical mirror is split. The large elliptical mirror 60 is arranged and assembled for each part such that the reflecting surface of each split mirror 61 matches the designed reflecting surface of the large elliptical mirror. Between each split mirror 61,
There may be gaps. Other configurations are the same as those in the first embodiment.

In the imaging optical system 20 having such a configuration, each reflecting surface of the split mirror 61 only forms a part of the reflecting surface of the entire large elliptical mirror 60. Therefore, the size of the reflecting surface of each of the split mirrors 61 may be smaller than the size of the reflecting surface of the entire large elliptical mirror, so that the split mirror 61 can be easily manufactured with high accuracy, and the cost can be reduced. In addition, since the large elliptical mirror 60 is formed by combining the split mirrors 61, it is needless to say that the reflecting surface of each split mirror 61 is arranged so as to completely coincide with a predetermined position as designed. Desirably. However, since the correction optical element 22 disposed in the vicinity of the exit pupil 30 corrects the aberration due to the arrangement error of each of the split mirrors 61, each of the split mirrors within a range where the correction optical element 22 can correct the aberration. With an arrangement error of 61, stable imaging performance can be obtained without any problem.
It should be noted that the large elliptical mirror 60 is a parabolic mirror,
The same effect can be obtained with a spherical mirror or a hyperboloid mirror.

FIG. 7 is a front view showing a configuration in which the first mirror is a spherical mirror 62 composed of a split mirror 63, and FIG. 8 is a sectional view taken along the line VIII-VIII in FIG. However, as shown in FIGS. 7 and 8, the first mirror may be a spherical mirror 62 obtained by combining the split mirrors 63. Each split mirror 63
Are combined such that their reflective surfaces match the respective portions of the reflective surface of the spherical mirror in design. Each of the split mirrors 63 has a central axis, and the trajectory obtained by rotating the arc about the central axis is the shape of the reflection surface of each split mirror 63. The outer shape of the split mirror 63 when viewed along its central axis is circular. Each of the split mirrors 63 is arranged such that the center axis of the split mirror 63 passes through the focal point of the spherical mirror 62. As described above, when the first mirror is the spherical mirror 62 and each of the split mirrors 63 is also rotationally symmetric about the center axis, each of the split mirrors 6
3 has the same shape and is simple, and the split mirror 63 is further formed.
And the spherical mirror 62 can be manufactured in a short time and at low cost.

Embodiment 5 FIG. FIG. 9 is a side view showing a configuration of a correction optical element in an imaging optical system according to Embodiment 5 of the present invention. In FIG. 9, the correction optical element arranged near the exit pupil 30 is a lens 65 that is a light transmitting body. The refractive index of the lens 65 is larger than that of the surroundings, and the thickness is adjusted to correct the aberration. The light beam reflected by the small ellipsoidal mirror 26 is
Is transmitted to the image detector 27 to form an image.
Reference numeral 7 is arranged on the back side of the lens 65 with respect to the small elliptical mirror 26. Other configurations are the same as in the first embodiment.

For example, if there is a portion depressed from a predetermined shape in the large ellipsoidal mirror 23, the ray bundle at that portion has a longer distance to reach the reflection surface of the large ellipsoidal mirror 23, and a normal predetermined light Reflects later than reflection. Since the light beam has a lower propagation velocity in the lens 65 having a large refractive index than the surroundings, the thickness of the lens 65 corresponding to the concave portion of the large ellipsoidal mirror 23 in the exit pupil 30 is recovered in order to recover the delay. The size has been reduced. That is, by reducing the thickness of the lens 65 having a small propagation speed and shortening the time when light passes through the lens 65, a portion having a smaller thickness than light passing through other portions of the lens 65 can be reduced. The light that passes is relatively advanced. As a result, it is possible to recover the delay in the portion where the thickness of the lens 65 is small, and it is possible to correct the aberration. Therefore, the same effect as that of the first embodiment can be obtained.

Embodiment 6 FIG. FIG. 10 is a side view showing a configuration of a correction optical element in an imaging optical system according to Embodiment 6 of the present invention. In FIG. 10, a plurality of correction optical elements 70 (for example, 2
), Which have lenses 71 and 72 as light transmitting bodies. The light beam reflected by the small ellipsoidal mirror 26 passes through the correction optical element 70 and is imaged by the image detector 27. Located on the side. Also, the lenses 71 and 72
Are spaced apart from each other by the small ellipsoidal mirror 26 and the image detector 2
7 are arranged. Another configuration is the first embodiment.
Is the same as

The correcting optical element 70 having such a configuration adjusts the thickness of one or both of the lens 71 and the lens 72 so that the aberration due to the unevenness of the reflecting surface of the large ellipsoidal mirror 23 as in the fifth embodiment. Can be corrected. Also, for example, like the lens arrangement of a camera, the lenses 71 and 7
By combining the two, it is generated by an arrangement error of the large ellipsoidal mirror 23, the hyperboloidal mirror 24, the plane reflection mirror 25, and the small ellipsoidal mirror 26, or is eliminated by a single lens generated in the entire light collecting optical system 21. Various aberrations such as spherical aberration that cannot be achieved can be reduced. Further, the distance between the lenses 71 and 72 can be changed to provide a zoom function.

Therefore, if the correction optical element 70 is not only composed of two lenses but also composed of three or more lenses arranged and combined, not only the aberration due to the unevenness of the reflection surface of the large elliptical mirror 23 but also the spherical aberration, for example, And other aberrations can be corrected.

Embodiment 7 FIG. FIG. 11 is a side view showing a configuration of a correction optical element in an imaging optical system according to Embodiment 7 of the present invention. In FIG. 11, the correction optical element 75 arranged near the exit pupil 30 has a lens assembly 76 that is a light transmitting body. The lens assembly 76 is configured by adhering lenses 77 and 78, which are light transmitting portions, in close contact with each other. Since the light beam reflected by the small ellipsoidal mirror 26 passes through the correction optical element 75 and is imaged by the image detector 27, the image detector 27 is located on the back of the lenses 77 and 78 with respect to the small ellipsoidal mirror 26. Located on the side. Also,
The lens 78 is attached to the lens 77 on the image detector 27 side. Further, the refractive index of the lens 77 is different from that of the lens 78, and the lens 77 is a convex lens and a lens 78.
Is a concave lens. Other configurations are the same as those of the fifth embodiment.

Here, the lens has a different refractive index depending on the wavelength of light. Therefore, light having a plurality of overlapping wavelengths is refracted in different directions depending on the wavelength when it enters the lens, and is separated into, for example, blue (F line), yellow (d line), and red (C line). Such a phenomenon is called dispersion. Among lenses, there are various lenses ranging from a lens having a large difference in refractive index depending on the wavelength, that is, a large dispersion characteristic, to a lens having a small refractive index, ie, having a small dispersion characteristic. Since the direction of refraction of a lens having a large dispersion characteristic differs greatly depending on the wavelength (color) of light, light of each wavelength forms an image at a different point, and chromatic aberration becomes remarkable.

The lens 77 is a lens having a small dispersion characteristic, such as a crown glass, and the lens 78 is a lens having a large dispersion characteristic, such as a flint glass. The refractive power (the ability to bend light) of the lens 77 is larger than the refractive power of the lens 78. Therefore, the refractive power of the lens assembly 76 has the function of the convex lens of the lens 77. Further, since the lens 77 is a convex lens and the lens 78 is a concave lens, the lens 78 refracts the light refracted and dispersed by the lens 77 in a direction to return the dispersion by the lens 78. At this time, the lens 78 has a smaller refracting power than the lens 77 but has a large dispersion characteristic, so that light having different wavelengths can be imaged at the same point.

Since such a correction optical element 75 is constructed, the thickness of the lens 77 and the lens 78 is reduced by the large elliptical mirror 23.
The same effect as in the fifth embodiment can be obtained by adjusting the reflection surface according to the unevenness of the reflection surface. Further, since the refractive power of the lens 77 is larger than the refractive power of the lens 78 and the dispersion characteristic of the lens 77 is smaller than the dispersion characteristic of the lens 78, and the lens 77 is a convex lens and the lens 78 is a concave lens, The refractive power of the lens 76 has the function of the refractive power of the lens 77, and the lens 78 can form light of two different wavelengths at the same point, thereby reducing chromatic aberration. Further, since the lens 77 and the lens 78 are in close contact with each other, they can be easily handled as one.
In addition, since the relative relationship between the lens 77 and the lens 78 is constant, the arrangement error is smaller than when a separate lens is arranged.

Note that, even if the refractive power of the lens 77 is smaller than the refractive power of the lens 78, it is sufficient if the light beam from the small ellipsoidal mirror 26 can form an image on the image detector 27. In this case, in order to correct the chromatic aberration, the dispersion characteristic of the lens 77 is changed to the lens 7.
8 is larger than the dispersion characteristic.

In addition, irrespective of the surface shapes of the lens 77 and the lens 78, chromatic aberration can be corrected if the direction of the light refracted by the lens 77 is refracted in the direction of returning by the lens 78. .

In the lens assembly 76, not only two lenses but also three or more lenses may be adhered to each other. By doing so, chromatic aberration can be reduced, and other aberrations can be corrected by adjusting the shape and combination of the lenses.

Embodiment 8 FIG. FIG. 12 is a side view showing a configuration of a correction optical element in an imaging optical system according to Embodiment 8 of the present invention. In FIG. 12, the correction optical element 80 arranged near the exit pupil 30 includes a plurality (for example, 2
One) is arranged. Each lens assembly 76
Need not have the same shape. Each lens combination 76 is arranged in the direction in which the light beam reflected by the small ellipsoidal mirror 26 travels. Further, the image detector 27 is a small ellipsoidal mirror 26.
Is arranged at a position where the light beam reflected by the light passes through the correction optical element 80 and forms an image. Therefore, the light flux is disposed on the back side of the correction optical element 80 with respect to the small ellipsoidal mirror 26. Other configurations are the same as those of the fifth embodiment.

Since the correcting optical element 80 is configured as described above, the chromatic aberration can be reduced by each lens combination 76, and a plurality of lens combinations 76 are arranged at an interval, so that the lens arrangement of the camera can be reduced. As described above, many aberrations can be corrected, and a zoom function can be provided by changing the distance between the lens combined bodies 76.

It should be noted that the lens assembly 76 may be formed by bonding not only two lenses but also three or more lenses in close contact with each other.
6 may be arranged at intervals of three or more, instead of two. By doing so, other various aberrations can be further reduced.

Embodiment 9 FIG. 13 is a side view showing a configuration of a correction optical element in an imaging optical system according to Embodiment 9 of the present invention. In FIG. 13, the correction optical element 8
Reference numeral 5 includes a light reflector 86 having a reflection surface, and a lens 87 which is a light transmission member adhered to and adhered to the reflection surface. In the correction optical element 85, the reflection surface of the light reflector 86 is substantially directed to the small ellipsoidal mirror 26, and all the light beams reflected by the small ellipsoidal mirror 26 pass through the lens 87. . Reflection surface of light reflector 86 and lens 87
Are adjusted so that various aberrations are corrected small. Other configurations are the same as in the first embodiment.

The light beam reflected by the small ellipsoidal mirror 26 is reflected by the correction optical element 85 and is imaged by the image detector 27. In the correction optical element 85, the light beam is first transmitted from the surface of the lens 87. Incident. Since the surface shape of the lens 87 is uneven, the light beam is refracted in different directions at each part of the surface, and the wavefront shape also changes. Thereafter, the light beam proceeds at a reduced speed through the lens 87 having a large refractive index, and is reflected by the reflection surface of the light reflector 86 having a surface having irregularities. The reflected light beam changes its wavefront shape due to the unevenness of the reflecting surface and proceeds through the lens 87. Again, the surface of the lens 87 is refracted in different directions by the unevenness of the surface shape at each portion, and the wavefront shape changes to detect an image. Go to the container 27.

Therefore, the light beam including various aberrations reflected by the small ellipsoidal mirror 26 is reflected on the surface of the lens 87, the reflecting surface of the light reflector 86, and the light beam at each portion of the light beam on the surface of the lens 87. By changing the direction and speed, various aberrations are corrected to be small as a whole of the correction optical element 85. For this reason, the correction optical element 85 has a portion that corrects various aberrations of the light beam twice more on the surface of the lens 87 as compared with a case where various aberrations of the light beam are corrected only by the reflection surface of the light reflector. As a result, various aberrations can be further reduced.

Embodiment 10 FIG. FIG. 14 is a side view showing a configuration of a correction optical element in an imaging optical system according to Embodiment 10 of the present invention. In FIG. 14, the correction optical element 90 has a light reflector 91 having a reflection surface, and a lens 92 which is a light transmission member disposed at an interval facing the reflection surface. In the correction optical element 90, the reflection surface of the light reflector 91 is substantially directed to the small ellipsoidal mirror 26, and all the light beams reflected by the small ellipsoidal mirror 26 pass through the lens 92 before hitting the reflection surface. It has become.
The thickness of the reflecting surface of the light reflector 91 and the thickness of each part of the lens 92 are adjusted so as to correct various aberrations small. Other configurations are the same as in the first embodiment.

As in the ninth embodiment, the light beam including various aberrations reflected by the small ellipsoidal mirror 26 first passes through the surface of the lens 92 on the small ellipsoidal mirror 26 side (hereinafter referred to as the first surface 92a). The light beam enters the light source 92 and is refracted in different directions at each portion of the light beam by the unevenness of the first surface 92a, and the wavefront shape changes. Thereafter, the light beam is refracted on the surface of the lens 92 facing the reflection surface of the light reflector 91 (hereinafter, referred to as a second surface 92b), reflected on the reflection surface of the light reflector 91, and again on the second surface 92.
The light is refracted at b, and refracted at the first surface 92a, and is imaged by the image detector 27.

Accordingly, the light beam including various aberrations reflected by the small ellipsoidal mirror 26 passes through the first surface 92 a of the lens 92 and the second light beam
The surface 92b, the reflecting surface of the light reflector 91, and again the second surface 92
b. Further, various aberrations are corrected to be small by changing the direction and speed of the light beam in each portion of the light beam on a total of five surfaces of the first surface 92a. Accordingly, various aberrations can be further reduced as compared with the ninth embodiment.

Embodiment 11 FIG. FIG. 15 is a side view showing a configuration of a correction optical element in an imaging optical system according to Embodiment 11 of the present invention. In FIG. 15, the correction optical element 95 includes a light reflector 96 having a reflection surface 96a, and a lens combination 97 which is a light transmission member disposed at an interval facing the reflection surface 96a. I have. The lens assembly 97 includes a plurality of (eg, two) light transmission units.
Of the first lens 98 and the second lens 99 of the bonding surface 1
At 00, they are adhered to each other. The correction optical element 95 is a reflection surface 96 of the light reflector 96.
a substantially faces the small elliptical mirror 26 side. Second lens 9
Reference numeral 9 is arranged such that a surface opposite to the bonding surface 100 (hereinafter, referred to as a second lens surface 101) faces the reflection surface 96a. The first lens 98 has a bonding surface 100
(Hereinafter, referred to as the first lens surface 102) is located on the small ellipsoidal mirror 26 side. Therefore, all the light beams reflected by the small ellipsoidal mirror 26 are
And then passes through a lens 99 before hitting the reflection surface 96a of the light reflector 96. Light reflector 96
And the thickness of each part of the lens 98 and the lens 99 are adjusted so as to correct various aberrations small. Other configurations are the same as in the first embodiment.

The ray bundle including various aberrations reflected by the small ellipsoidal mirror 26 first enters the lens 98 from the first lens surface 102 of the lens 98 and is incident on the first lens surface 102 as in the tenth embodiment. Due to the unevenness, each part of the light beam is refracted in a different direction and the wavefront shape changes. Thereafter, the light beam is refracted by the bonding surface 100 and the second lens surface 101,
The light hits the reflection surface 96 a of the light reflector 96. The light beam reflected by the reflection surface 96a is refracted again by the second lens surface 101, the bonding surface 100, and the first lens surface 102, and forms an image by the image detector 27.

Therefore, the ray bundle including various aberrations reflected by the small ellipsoidal mirror 26 is transmitted to the first lens surface 102 of the lens 98.
Twice, the bonding surface 100 twice, the second lens surface 1
The aberrations are corrected to be small by changing the direction and speed of the light beam twice, ie, twice at 01 and once at the reflection surface 96a of the light reflector 96, seven times in total. Therefore, Embodiment 1
Various aberrations can be further reduced as compared to zero.

Further, the first lens 98 and the second lens 99
If the correction optical element 95 is capable of forming a light beam as a whole with the image detector 27, the chromatic aberration can be corrected and the same effect as in the seventh embodiment can be obtained.

Embodiment 12 FIG. FIG. 16 is a side view showing a configuration of a correction optical element in an imaging optical system according to Embodiment 12 of the present invention. In FIG. 16, the exit pupil 30
The correction optical element 105 disposed near the light reflector 10
6 and a first lens 107 and a second lens 108 which are a plurality (for example, two) of light transmitting bodies. The light reflector 106 has a reflection surface 106a facing the small ellipsoidal mirror 26 side. The first lens 107 includes a first surface 107a opposed to the reflection surface 106a at an interval, and a first surface 10a.
7a, and has a second surface 107b opposed to the second lens 108 at an interval. Second lens 1
Reference numeral 08 denotes a first surface 108a opposed to the second surface 107b of the first lens 107 at an interval, and a second surface 108 located on the back of the first surface 108a and facing the small ellipsoidal mirror 26.
b. Therefore, the second lens 108 and the first lens 107 are arranged toward the light reflector 106, and the light beam reflected by the small ellipsoidal mirror 26 passes through the second lens 108 and the first lens 107 and is The light is reflected at 106a, passes through the first lens 107 and the second lens 108 again, and is imaged by the image detector 27. Other configurations are the same as in the first embodiment.

The light beam including various aberrations reflected by the small ellipsoidal mirror 26 first enters the second lens 108 from the second surface 108b of the second lens 108, and is reflected by the unevenness of the second surface 108b. The light is refracted in different directions at the portions and the wavefront shape changes. Thereafter, the light beam is transmitted to the first surface 108a and the second surface 10a.
7b and the first surface 107a refracts and strikes the reflecting surface 106a of the light reflector 106. The light beam reflected by the reflection surface 106a is again transmitted to the first surface 107a, the second surface 107b, and the first surface 1a.
08a, refracted by the second surface 108b, and proceeded to the image detector 27.
Is imaged.

Therefore, the light beam including various aberrations reflected by the small ellipsoidal mirror 26 includes the first surface 107a, the second surface 107b,
Since the direction or speed can be adjusted twice each on the first surface 108a and the second surface 108b and once on the reflecting surface 106a, the various aberrations can be further reduced.

Further, by using a plurality of lenses, a special function such as a zoom function can be provided by changing the distance between the lenses. In addition, by using three or more lenses, various aberrations can be further reduced, and the effect of the zoom function increases.

Embodiment 13 FIG. FIG. 17 is a side view showing a configuration of a correction optical element in an imaging optical system according to Embodiment 13 of the present invention. In FIG. 17, the exit pupil 30
The correction optical element 110 disposed near the light reflector 11
1 and a plurality of (for example, two) light transmitting bodies, a first lens connecting body 112 and a second lens connecting body 113. First lens combination 112 and second lens combination 11
3 are opposed to each other at an interval. Further, the first lens unit 112 faces the reflection surface 111a of the light reflector 111 at an interval. First lens assembly 112
Is configured such that a first lens first portion 114 serving as a light transmitting portion and a first lens second portion 115 serving as a light transmitting portion are closely adhered to each other on a first bonding surface 112a.
The second lens assembly 113 also includes a second lens first part 116 that is a light transmitting part and a second lens second part 117 that is a light transmitting part.
Are closely adhered to each other on the second bonding surface 113a and bonded to each other. The first lens first portion 114 is located on the back surface of the first bonding surface 112a and is located on the reflection surface 111a.
The first lens 114 has a first surface 114a facing the
15 is located on the back of the first bonding surface 112a and
It has a second surface 115a facing the lens assembly 113. The second lens first part 116 is the second bonding surface 1
The second lens second portion 117 is located on the back surface of the second bonding surface 113a and faces the small ellipsoidal mirror 26 side. It has a second surface 117a. Accordingly, the light beam reflected by the small ellipsoidal mirror 26 passes through the second lens combination 113 and the first lens combination 112, is reflected by the reflection surface 112a, and is again reflected by the first lens combination 112 and the second lens combination. It passes through the body 113. Other configurations are the same as in the first embodiment.

The ray bundle including various aberrations reflected by the small ellipsoidal mirror 26 first enters the second lens second part 117 from the second surface 117a of the second lens second part 117 in the second lens unit 113. Then, due to the unevenness of the second surface 117a, each portion of the light beam is refracted in a different direction, and the wavefront shape changes. After that, the light beam passes through the second bonding surface 113a and the first surface 1
16a, the second surface 115a, the first bonding surface 112a, and the first surface 114a.
This corresponds to 11a. The light beam reflected by the reflecting surface 111a is
Again, the first surface 114a, the first bonding surface 112a,
Surface 115a, first surface 116a, second bonding surface 113
a and the light is refracted by the second surface 117a and is formed by the image detector 27.

Therefore, the light beam including various aberrations reflected by the small ellipsoidal mirror 26 includes the first surface 114a, the first bonding surface 112a, the second surface 115a, the first surface 116a, and the second bonding surface 113a. Since the direction or speed can be adjusted twice each on the second surface 117a and once on the reflecting surface 111a, a total of 13 times, various aberrations of the light beam can be further reduced.

Further, since the first lens combination 112 and the second lens combination 113 having the lenses in close contact with each other are used, the handling is easy and the chromatic aberration can be surely corrected. Further, a zoom function can be provided by changing the distance between the first lens combination 112 and the second lens combination 113.

Note that the first lens combination 112 and the second lens combination 113 can reduce chromatic aberration and other various aberrations as a whole even if not only two lenses but also three or more lenses are in close contact. It can be corrected. Also, the first lens combination 11 which is two light transmitting bodies
A configuration in which not only the second and second lens combined bodies 113 but also three or more light transmitting bodies are arranged at intervals may further reduce various aberrations as a whole and increase the effect of the zoom function.

It is common practice to correct a variety of aberrations by arranging a plurality of lenses. However, when this lens array is viewed from the side in this array direction, the lens array becomes bilaterally symmetric. In general, it is known that it is easy to correct various aberrations. Therefore, in the tenth to thirteenth embodiments, the correction optical element is bilaterally symmetric such that the shape of the light transmitting body such as a lens has a central axis along the arrangement direction, and If the reflecting surface is also configured to be a plane perpendicular to the central axis, the path of the light beam passing through the correction optical element is symmetrical, and the right and left lenses of the light transmitting body are substantially This is similar to the case where the light beam passes through a state where the reflectors are symmetrically arranged. Therefore, by making the shape of the correction optical element symmetrical in this way, it becomes easy to correct various aberrations.

In the fourth embodiment or the tenth to thirteenth embodiments, if the light reflector of the correction optical element is a deformable mirror, the third embodiment
It has the same effect as. Further, in Embodiments 4 to 13, if the correction optical element is provided with an angle control means capable of obtaining a signal from the angle detection means so that the angle of the correction optical element can be changed. Thus, the same effect as in the second embodiment can be obtained.

[0088]

As is apparent from the above description, according to the present invention, the imaging optical system according to the present invention has a condensing optical system having an exit pupil smaller than the entrance pupil on the image side. In the above, since it is provided with a correction optical element that is arranged near the exit pupil and corrects the aberration of the condensing optical system, the correction optical element smaller than the entrance pupil corrects the aberration at the entrance pupil. The same correction can be performed, and an imaging optical system with good imaging performance, easy correction, and low cost can be obtained.

Further, since the light collecting optical systems are all reflecting mirrors and do not have a lens, chromatic aberration peculiar to the lens does not occur.

Further, since the condensing optical system includes the first mirror having at least the entrance pupil, the shape of the first mirror can be reflected on the exit pupil.

Further, since the first mirror is an elliptical mirror,
Spherical aberration, coma, and astigmatism that cause resolution degradation can be reduced in a well-balanced manner, and good imaging performance can be obtained.

Since the first mirror is a spherical mirror, it is easy to manufacture and the cost is low.

Since the first mirror is a parabolic mirror,
It is easy to manufacture and low cost.

Further, since the first mirror is composed of a plurality of split mirrors, the first mirror can be partially manufactured with high accuracy, and the first mirror can be easily manufactured at low cost.

Since the shape of the reflecting surface of the reflecting mirror changes, the reflecting surface of the reflecting mirror is adjusted so as not to deviate from a predetermined shape due to aging or the like. The increase can be suppressed.

Further, since the reflecting mirror is provided with angle control means for changing the incident angle of light by rotating the reflecting mirror, when the line of sight of the object to be imaged changes due to vibration or the like. Also, it is possible to form an image of an object to be formed in a normal line-of-sight direction.

Further, the correction optical element has a light transmitting body having a refractive index different from that of the surroundings, and the aberration is corrected by the light transmitting body. The aberration at the entrance pupil can be easily corrected at low cost by the body.

Further, in the light transmitting body, a plurality of light transmitting portions having different refractive indices are stacked in close contact with each other, so that the plurality of light transmitting portions are not displaced relative to each other, and an arrangement error is prevented. And the handling becomes easy. Further, if the light transmitting portions have different dispersion characteristics, the generation of chromatic aberration can be suppressed by a combination.

Further, since the plurality of light transmitting bodies are arranged at intervals, various aberrations can be further corrected as a whole, and a zoom function is provided by changing the distance between the light transmitting bodies. Can be made.

The correction optical element has a light reflector having a reflection surface, and the aberration is corrected by the light reflector. The aberration at the entrance pupil can be corrected easily and at low cost, and the imaging optical system can be made compact by changing the traveling direction of light.

Further, since the light reflector is in close contact with the opposing light transmitting body, the reflecting surface of the light reflecting body is not only corrected for aberrations by only the light reflecting body but also reflected by the light transmitting body. The aberration of the light before and after the reflection on the surface is corrected, and the aberration can be corrected to be small.

Further, since the shape of the reflecting surface of the correcting optical element is changed, deterioration of the imaging performance is prevented even with respect to changes in state such as temperature and atmospheric pressure, vibration, distortion and aging. Can be prevented.

The condensing optical system has an aberration measuring means for measuring the aberration, and the reflection surface shape is changed based on the aberration measured by the aberration measuring means. Can be corrected according to the aberration at that time.

Further, since the correcting optical element is provided with angle control means for changing the incident angle of light by rotating the correcting optical element, the line-of-sight direction of the image-forming object changes due to vibration or the like. Even in such a case, it is possible to form an image of an object to be formed in a normal line-of-sight direction.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an imaging optical system according to Embodiment 1 of the present invention.

FIG. 2 is a schematic diagram of an imaging optical system according to Embodiment 2 of the present invention.

FIG. 3 is a schematic diagram of an imaging optical system according to Embodiment 3 of the present invention.

4 is a sectional perspective view of a part of the correction optical element 50 of FIG.

FIG. 5 is a front view of a first mirror of an imaging optical system according to Embodiment 4 of the present invention.

FIG. 6 is a sectional view taken along the line VI-VI in FIG. 5;

FIG. 7 is a front view showing a configuration in which the first mirror is a spherical mirror formed of a split mirror.

FIG. 8 is a sectional view taken along line VIII-VIII in FIG.

FIG. 9 is a side view showing a configuration of a correction optical element in an imaging optical system according to Embodiment 5 of the present invention.

FIG. 10 is a side view showing a configuration of a correction optical element in an imaging optical system according to Embodiment 6 of the present invention.

FIG. 11 is a side view showing a configuration of a correction optical element in an imaging optical system according to Embodiment 7 of the present invention.

FIG. 12 is a side view showing a configuration of a correction optical element in an imaging optical system according to Embodiment 8 of the present invention.

FIG. 13 is a side view showing a configuration of a correction optical element in an imaging optical system according to Embodiment 9 of the present invention.

FIG. 14 is a side view showing a configuration of a correction optical element in an imaging optical system according to Embodiment 10 of the present invention.

FIG. 15 is a side view showing a configuration of a correction optical element in an imaging optical system according to Embodiment 11 of the present invention.

FIG. 16 is a side view showing a configuration of a correction optical element in an imaging optical system according to Embodiment 12 of the present invention.

FIG. 17 is a side view showing a configuration of a correction optical element in an imaging optical system according to Embodiment 13 of the present invention.

FIG. 18 is a schematic diagram showing a configuration of a conventional imaging optical system.

[Explanation of symbols]

Reference Signs List 20 imaging optical system, 21 focusing optical system, 22, 70, 7
5, 80, 85, 90, 95, 105, 110 Correction optical element, 23, 60, 62 First mirror (ellipsoidal mirror, spherical mirror, parabolic mirror), 29 entrance pupil, 30 exit pupil, 40
Angle control means, 57 Aberration measurement means, 61, 63 split mirrors, 65, 71, 72, 76, 87, 92, 97, 10
7, 108, 112, 113 light transmitting body, 77, 78,
98, 99114, 115, 116, 117 Light transmitting part, 86, 91, 96, 106, 111 Light reflector.

Continued on the front page F term (reference) 2H039 AA02 AB02 AB12 AB14 AB22 AB24 AB32 AC00 2H042 DA10 DA21 DB14 DD04 DD10 DD11 DE00 2H043 BC01 BC08 CB00 CD02 CD04 2H087 KA15 NA01 PA01 PA02 PA17 PA18 PA19 PB02 PB04 QA19 QA21 QA19 QA19 QA19 RA27 TA00 TA01 TA02 TA06 TA08

Claims (17)

[Claims] 1. An imaging optical system having a converging optical system having an exit pupil smaller than an entrance pupil on an image side, comprising: a correction optical element arranged near the exit pupil for correcting aberration of the converging optical system. An imaging optical system, comprising: 2. The image forming optical system according to claim 1, wherein all of the light collecting optical systems are reflecting mirrors. 3. The imaging optical system according to claim 1, wherein the light-converging optical system includes a first mirror having at least the entrance pupil. 4. The imaging optical system according to claim 3, wherein the first mirror is an ellipsoidal mirror. 5. The imaging optical system according to claim 3, wherein said first mirror is a spherical mirror. 6. The imaging optical system according to claim 3, wherein said first mirror is a parabolic mirror. 7. The imaging optical system according to claim 3, wherein the first mirror is constituted by a plurality of split mirrors. 8. The reflection mirror according to claim 2, wherein a shape of the reflection surface is changed.
An imaging optical system according to any one of the above. 9. The reflection mirror according to claim 2, wherein the reflection mirror is provided with angle control means for rotating the reflection mirror to change an incident angle of light. Imaging optics. 10. The apparatus according to claim 1, wherein the correction optical element has a light transmitting body having a refractive index different from that of the surroundings, and the aberration is corrected by the light transmitting body. Item 10. The image forming optical system according to any one of Items 9. 11. The imaging optical system according to claim 10, wherein the light transmitting body includes a plurality of light transmitting portions having different refractive indices stacked in close contact with each other. 12. The light transmitting body according to claim 10, wherein a plurality of the light transmitting bodies are arranged at intervals.
2. The imaging optical system according to 1. 13. The correction optical element according to claim 1, further comprising a light reflector having a reflection surface, wherein the aberration is corrected by the light reflector. An imaging optical system according to any one of the above. 14. The imaging optical system according to claim 13, wherein the light reflector is in close contact with the light transmitting body whose reflecting surface is opposed to the light reflecting body. 15. The correction optical element according to claim 1, wherein said reflection surface shape is changed.
4. The imaging optical system according to 3. 16. The light-converging optical system has an aberration measuring means for measuring aberration, and the shape of the reflecting surface changes based on the aberration measured by the aberration measuring means. The imaging optical system according to claim 8 or claim 15, wherein 17. The correction optical element according to claim 1, further comprising an angle control unit configured to rotate the correction optical element to change an incident angle of light. 2. The imaging optical system according to item 1.