JPH1042172A - Wide view/large wavelength range image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric conversion element to match a large focual surface with simple constitution without the need of a mechanism for switching optical systems by using plural asperical mirror which are sequentially arranged so that they reflect incident light. SOLUTION: A light beam 100 is made incident and reflected on a first concave mirror 1, a convex mirror 2 and a second concave mirror 3. The light beam reflected on the concave mirror 3 is spectrally separated in different wavelengths in a spectral mirror 4. A transmitted light beam 100a is made incident on a first photoelectric conversion part 5 and a reflected light beam 100b to a second photoelectric conversion part 6. The concave mirrors 1 and 3 and the convex mirror 21 are the aspehrical mirrors, the optical system is constituted of the spherical mirrors and the optical system is constituted of the aspherical mirrors. Thus, light convergence and light diffusion can be executed by one surface and the respective mirrors correct spherical aberration, astigmatism and coma-aberration. Thus, a view becomes large since spherical aberration, astigmatism and coma-aberration aut of a center shaft are reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wide-field, wide-wavelength imaging device, and more particularly to a wide-field, wide-wavelength imaging device used in a remote sensing system or the like.

[0002]

2. Description of the Related Art Conventionally, optical systems include a lens system and a reflecting mirror system. The lens system has the disadvantage that the wavelength range is narrowed due to the occurrence of chromatic aberration, but has the advantage that a wide field of view is possible. On the other hand, the reflecting mirror system has an advantage that the wavelength range is wide, but has a disadvantage that the field of view is narrow.

The reflecting mirror system has high performance on the central axis of the reflecting mirror, but the field of view becomes narrow due to spherical aberration, astigmatism, and coma off the central axis.

As described above, in the conventional imaging system, a wide field of view and a wide wavelength range are not compatible.

Therefore, conventionally, a refractive optical system or a catadioptric system using both a lens and a reflecting mirror in the optical system has been used.

[0006] However, this refracting optical system or catadioptric system uses a refracting lens to enable wide-field imaging, but has a disadvantage that the wavelength range in which imaging can be performed is narrowed due to chromatic aberration. .

Therefore, in order to realize this wide wavelength range, Japanese Patent Application Laid-Open No. 63-78116 discloses an image pickup apparatus in which an optical system is switched according to the wavelength range to perform image pickup.

[0008]

However, Japanese Patent Application Laid-Open No.
The imaging apparatus disclosed in Japanese Patent No. 78116 has a drawback that the configuration becomes complicated because a mechanism for switching the optical system is required.

Further, in an imaging device having a wide field of view and a high resolution, the focal plane becomes large, so that there is a disadvantage that a photoelectric conversion element corresponding to the size of the focal plane is required.

SUMMARY OF THE INVENTION An object of the present invention is to provide a wide-field, wide-wavelength imaging apparatus which does not require a mechanism for switching an optical system and which can obtain a photoelectric conversion element suitable for a large focal plane with a relatively simple configuration. Is to do.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to an n (n is an integer of 2 or more) arrayed so that incident light is reflected, and the reflected light is incident and further reflected. ) Aspherical mirrors and electric signal conversion means for converting light reflected by the n-th aspherical mirror into electric signals.

Still another aspect of the invention is characterized in that the electric signal converting means is constituted by means for converting one image into an electric signal using a plurality of photoelectric conversion elements.

According to the present invention, a wide field of view and a wide wavelength range can be imaged by using only the aspherical mirror.

According to still another aspect of the present invention, it is possible to obtain a photoelectric conversion element suitable for a large focal plane with a relatively simple configuration.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a configuration diagram of the best embodiment of a wide-field, wide-wavelength imaging device according to the present invention.

The wide-field, wide-wavelength imaging apparatus includes a first concave mirror 1 on which a light ray 100 is incident, a convex mirror 2 on which a light ray 100 reflected by the first concave mirror 1 is incident, and a convex mirror 2
A second concave mirror 3 on which the light ray 100 reflected by
A spectroscopic mirror 4 in which the light beam 100 reflected by the second concave mirror 3 is split into different wavelength ranges, and a first photoelectric conversion unit 5 into which the light beam 100a transmitted through the spectroscopic mirror 4 is incident.
And the second photoelectric conversion unit 6 on which the light beam 100b reflected by the spectral mirror 4 is incident.

These concave mirrors 1 and 3 and convex mirror 2 are constituted by aspherical mirrors. The aspheric mirror refers to, for example, a mirror having a shape of a paraboloid of revolution expressed by a quadratic equation or more and a hyperboloid of revolution expressed by a cubic equation or more.

As described above, by forming the optical system with the aspherical mirror, each of the mirrors can correct the aberrations such as spherical aberration, astigmatism, and coma in addition to focusing and diffusing light on one surface. Can be shared.

Therefore, since the spherical aberration, astigmatism and coma aberration outside the central axis are reduced, the field of view is widened.

On the other hand, conventional mirrors and lenses are constituted by spherical surfaces that can be expressed by a simple linear expression.

The concave mirrors 1 and 3 are formed asymmetrically with respect to the central axis of the spherical surface or do not include the central axis (hereinafter referred to as off-axis), and the convex mirror 2 is formed symmetrically with respect to the central axis. I have.

Here, the off-axis will be described. First, the configuration of a conventional optical system will be described. FIG. 14 is a configuration diagram of a conventional lens system, and FIG. 15 is a configuration diagram of a conventional reflecting mirror system.

In FIG. 14, light beam 100 is convex lens 1
01, concave lens 102, concave lens 103, convex lens 10
A focal point F is formed via the reference numeral 4. C represents the central axis of the lens.

In FIG. 15, the light beam 100 is
The focal point F is formed via the convex mirrors 5a and 105b and the convex mirror 106. C represents the central axis of the lens.

As described above, all the conventional optical systems are arranged rotationally symmetric with respect to the central axis C.

Next, the optical system of the present invention will be described.
FIG. 2 is a configuration diagram of an off-axis lens system, and FIG. 3 is a configuration diagram of an off-axis reflection mirror system.

In FIG. 2, the light beam 100 is
0, concave lens 111, concave lens 112, convex lens 113
A focus F is formed through. C represents the central axis of the lens.

In FIG. 3, light ray 100 is concave mirror 115
And a focal point F is formed via the convex mirror 116. C represents the central axis of the lens.

As described above, the lenses 110 to 113 and the mirrors 115 and 116 are formed in a shape not including the central axis.

As described above, the degree of freedom of arrangement is increased by configuring the optical system with an off-axis lens system or a reflecting mirror system. In the present invention, the concave mirrors 1 and 3 are off-axis among the reflecting mirrors.

In particular, with respect to the reflecting mirror, only one or two planes can be arranged in a coaxial optical system (rotationally symmetric optical system) (FIG. 1).
On the other hand, by displacing the axis, it is possible to arrange three or more surfaces (see FIGS. 1 and 3).

Further, in the coaxial optical system, a light-shielding portion 106 is generated as shown in FIG. 15, but such a light-shielding portion 106 can be eliminated by off-axis (see FIGS. 1 and 3).

FIG. 4 is a cross-sectional view of the off-axis concave mirror 115 not including the center axis C, and FIG. 5 is a cross-sectional view of the off-axis concave mirror 117 asymmetric with respect to the center axis C. Thus, there are two types of off-axis. In the present invention, the concave mirror 11 is used.
5, 117 can be used.

Returning to FIG. 1, the concave mirrors 1 and 3 and the convex mirror 2 are arranged symmetrically with respect to the central axis C of the convex mirror 2. Next, this symmetric arrangement will be described.

FIG. 6 is a diagram showing an example of a symmetric arrangement of the optical system. In this example, an optical system is configured by a convex lens 120, a concave lens 121, and a convex lens 122 that are symmetric with respect to a central axis C. Thus, the lenses 120 to 12 with respect to the central axis C are
2 are arranged symmetrically so that each of the lenses 120 to 12
Since the aberration due to 2 is canceled out, the aberration can be almost eliminated. Therefore, correction of aberration becomes easier when the arrangement is closer to the symmetric arrangement than when the arrangement is asymmetric.

In the present invention, the same construction as the lenses 120 to 122 is adopted by the concave mirrors 1 and 3 and the convex mirror 2. The aberrations are canceled out by the configuration of the concave, convex, and concave reflecting surfaces (1, 2, 3), and the aberration generated by the component deviating from the symmetry can be corrected by adjusting the surface of each mirror surface.

Next, the photoelectric conversion units 5 and 6 will be described. Since the configurations of the photoelectric conversion units 5 and 6 are the same, only the photoelectric conversion unit 5 will be described.

The photoelectric conversion unit 5 includes a plurality of multi-element detectors (eg, charge-coupled devices (CCDs)) arranged. FIG. 7 is a configuration diagram when the charge-coupled devices are arranged one-dimensionally, and FIG. 8 is a configuration diagram when the charge-coupled devices are arranged two-dimensionally.

When the charge-coupled devices 121 are arranged one-dimensionally as shown in FIG. 7, an image is converted into an electric signal one scan at a time, and an electric signal of one screen is generated by scanning one screen.

Also, as shown in FIG.
Are two-dimensionally arranged, the image is converted into an electric signal for each screen.

As described above, by configuring the photoelectric conversion unit 5 by arranging a plurality of charge-coupled elements 121, a wide field of view can be accommodated, and even when the focal plane is curved, Distortion can be corrected by adjusting the arrangement of the charge-coupled devices 121 to the curved shape.

With this configuration, high-resolution imaging of 6 degrees or more can be performed in the wavelength range from ultraviolet rays to thermal infrared rays.

In this embodiment, the charge coupled device 121
Are arranged via the spectral mirror 4, but it is of course possible to perform photoelectric conversion without using the spectral mirror 4.

Next, the configuration of the photoelectric conversion unit 5 will be described. FIG. 9 is a schematic explanatory view of the configuration of the photoelectric conversion unit.

The photoelectric conversion unit 5 includes a prism 130 for dividing the light beam 100 into two, and two charge-coupled device groups 131 and 13.
2, the light beam 100 is divided into the light beam 100a and the light beam 1 by the half mirror surface 130a provided in the prism 130.
00b.

This prism 130 is different from the spectroscopic mirror 4 in that it does not split light into different wavelength ranges, but
It has only the function of dividing 0 into two.

Therefore, the images incident on the charge-coupled device groups 131 and 132 are the same. Next, synthesis of an image by the charge-coupled device groups 131 and 132 will be described.

FIGS. 10 to 12 are schematic explanatory views showing the process of synthesizing images. 10 to 12 show the entire image 135 due to the incident light.

In the whole image 135, a hatched portion 136 in FIG. 10 is a region where the charge-coupled device group 131 converts to an electric signal, and a hatched portion 137 in FIG.
Numeral 32 denotes a region to be converted into an electric signal. Then, the charge-coupled device groups 131 and 132 convert the 2
The two regions 136 and 137 are combined by a signal combining unit (not shown) provided in the photoelectric conversion unit 5, and one image (region 136 + region 137) shown in FIG. 12 is generated.

Thus, by using a plurality of charge-coupled device groups, it is possible to perform photoelectric conversion of an image having a wider field of view.

An amplifying circuit and a signal processing circuit are provided after the photoelectric conversion unit 5, and the overall configuration including these will be described last.

FIG. 13 is an overall configuration diagram of a wide-field, wide-wavelength imaging device. The wide-field, wide-wavelength imaging apparatus includes reflecting mirror units 1 to 3 to which the light beam 100 is input, a spectral mirror 4 for separating the light beam 100 reflected by the reflecting mirror units 1 to 3 into different wavelength ranges, Of the photoelectric conversion unit 5 to which the light beam 100a is input, an amplification circuit 7 for amplifying the output signal of the photoelectric conversion unit 5, the photoelectric conversion unit 6 to which the other split light beam 100b is input, and the photoelectric conversion unit 6. It comprises an amplifier circuit 8 for amplifying an output signal, and a signal processing circuit 9 for synthesizing the output signals of the amplifier circuits 7 and 8 and converting it into a transmittable signal 140.

[0053]

According to the present invention, incident light is reflected,
N (n is an integer of 2 or more) aspherical mirrors sequentially arranged so that the reflected light is incident and further reflected, and an electric signal converting means for converting the light reflected by the nth aspherical mirror into an electric signal. Therefore, imaging in a wide field of view and a wide wavelength range can be performed without providing a mechanism for switching the optical system.

According to still another aspect of the present invention, since the electric signal converting means is constituted by means for converting one image into an electric signal by using a plurality of photoelectric conversion elements, it is possible to meet a large focal plane with a relatively simple structure. A photoelectric conversion element can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a preferred embodiment of a wide-field and wide-wavelength imaging device according to the present invention.

FIG. 2 is a configuration diagram of an off-axis lens system.

FIG. 3 is a configuration diagram of an off-axis reflecting mirror system.

FIG. 4 is a sectional view of an off-axis concave mirror that does not include a central axis.

FIG. 5 is a cross-sectional view of an off-axis concave mirror that is asymmetric with respect to a central axis.

FIG. 6 is a configuration diagram of an example of a symmetric arrangement of an optical system.

FIG. 7 is a configuration diagram when charge-coupled devices are arranged one-dimensionally.

FIG. 8 is a configuration diagram when charge-coupled devices are two-dimensionally arranged.

FIG. 9 is a schematic diagram illustrating a configuration of a photoelectric conversion unit.

FIG. 10 is a schematic explanatory view showing a process of combining images.

FIG. 11 is a schematic explanatory view showing a process of combining images.

FIG. 12 is a schematic explanatory view showing a process of combining images.

FIG. 13 is an overall configuration diagram of a wide-field-of-view wide-wavelength imaging device.

FIG. 14 is a configuration diagram of a conventional lens system.

FIG. 15 is a configuration diagram of a conventional reflecting mirror system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st concave mirror 2 convex mirror 3 2nd concave mirror 4 spectral mirror 5 1st photoelectric conversion part 6 2nd photoelectric conversion part 121 charge coupling element 130 prism 130a half mirror surface 131,132 charge coupling element group

Claims (8)

[Claims] 1. An incident light is reflected, and the reflected light is reflected by n (n is an integer of 2 or more) aspheric mirrors which are sequentially arranged to be incident and further reflected, and an nth aspheric mirror. A wide-field, wide-wavelength imaging device, comprising: an electric signal conversion unit that converts light into an electric signal. 2. The wide-field wide-band imaging device according to claim 1, wherein the odd-numbered aspherical mirror is configured by a concave mirror, and the even-numbered aspherical mirror is configured by a convex mirror. 3. The odd-numbered aspherical mirror is formed to be asymmetric with respect to a central axis of a spherical surface or to have a shape not including the central axis, and the even-numbered aspherical mirror is formed to be centrally symmetric. The wide-field-of-view wide-wavelength imaging device according to claim 1. 4. The wide field of view according to claim 1, wherein said electric signal converting means is means for converting one image into an electric signal using a plurality of photoelectric conversion elements. Wavelength range imaging device. 5. The electric signal converting means further comprises a spectroscopic means for dispersing the light reflected by the n-th aspherical mirror into different wavelength ranges, and the light disperse by the dispersing means is provided for each of the plurality of light beams. The wide-field, wide-wavelength imaging device according to claim 4, wherein the image is input to a photoelectric conversion element. 6. The electric signal converting means refracting means for refracting light reflected by the n-th aspherical mirror in two directions, and photoelectrically converting different portions of two images obtained by the refracting means. 5. The image processing apparatus according to claim 4, further comprising: two sets of the plurality of photoelectric conversion elements; and signal combining means for combining the electrical signals obtained from the plurality of photoelectric conversion elements to generate one image signal. The wide-field wide-wavelength range imaging device according to the above. 7. The wide-field wide-wavelength imaging device according to claim 4, wherein the plurality of photoelectric conversion elements are arranged one-dimensionally. 8. The wide-field wide-wavelength imaging apparatus according to claim 4, wherein the plurality of photoelectric conversion elements are arranged two-dimensionally.