JPH09166400A - Double wavelength infrared image homing equipment by double wavelength separation optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To integrate a double wavelength separation optical system with an infrared detector of each wavelength and to make them mountable on gimbals. SOLUTION: Infrared rays R are received by a main mirror 1a and a submirror 1b and a long wavelength band is reflected like R1 by an infrared filter 1c, while a medium wavelength band R2 is transmitted. The long wavelength band R1 is reflected by a reflector 1d and enters a relay lens 1e, while the medium wavelength band R2 enters a relay lens 1f. The infrared rays are made parallel lights by the relay lenses 1e and 1f respectively and these lights enter the respective vacuum vessels 2a and 3a of infrared detectors 2 and 3 and are led to imaging lenses 2b and 3b, imaged on two-dimensional infrared sensors 2c and 3c and converted into electric signals respectively. Marks 2d and 3d denote coolers. This double wavelength separation optical system and the detectors of the two wavelengths are integrated to be small in size and light in weight and can be mounted on gimbals and, therefore, infrared image homing equipment of an airframe can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-wavelength infrared image homing apparatus which is a combination of a two-wavelength separation optical system and a detector assembly part in which a cooler and a sensor are integrated.

[0002]

2. Description of the Related Art Conventionally, there is no two-wavelength infrared image homing device equipped with a two-wavelength infrared detector on a gimbal.
A wavelength infrared image homing apparatus will be described. Figure 3 shows the medium wavelength (3-5μ) mounted on the gimbal in this case.
m band) or long wavelength (8-12 μm band) imager 3
0 indicates that the imager 30 includes a refracting optical system 21 that collects infrared rays, a two-dimensional infrared sensor 22, and a cooler 2.
3, the cooling type infrared detector 20 including the cold shield 24 and the vacuum container 25 is integrally assembled.

In a homing device used for a flying object, an imager 30 in which the optical system 21 and the infrared detector 20 including a sensor, a cooler, a shield, etc. are integrated in this way is mounted on a gimbal (not shown). Has become. In order to realize a two-wavelength compound homing device for medium-wavelength and long-wavelength infrared light, it is necessary to mount the imager of each wavelength on the gimbal at the same time, which is a large-scale device and cannot be mounted on a flying object, etc. I haven't.

[0004]

First of all, a conventional one-wavelength infrared imager 3 as shown in FIG.
Mounting two 0s on the gimbal requires two aperture diameters, and cannot be realized with an appropriate homing device size as described above.

Next, in order to make the aperture diameter a proper size,
If the condensing optical system is common to two wavelengths, it is necessary to separate the two wavelengths. In order to bring out the performance of the two-dimensional infrared sensor, unnecessary infrared rays from the inside of the homing device are incident on the sensor surface. In order to prevent it, it is necessary to take so-called aperture matching so that the aperture of the cold shield hits the aperture restriction of the optical system, so the length of the optical system becomes longer,
Since it is difficult to secure the movable range when the gimbal is mounted, it has not been realized at present.

The present invention includes a condensing optical system having two common wavelengths and two converging optical systems.
An object of the present invention is to provide a two-wavelength infrared image homing device which enables a combination of a wavelength separation optical system and two wavelength detectors to be mounted on a gimbal, and which has an appropriate aperture diameter and optical system length. .

[0007]

SUMMARY OF THE INVENTION Therefore, the present invention is directed to a condensing optical system including a main mirror which receives and reflects infrared rays, and a secondary mirror which receives infrared rays reflected from the main mirror and reflects the infrared rays in the optical axis direction. A filter which is arranged between the primary mirror and the secondary mirror of the same condensing optical system, reflects the secondary mirror, reflects the first wavelength band of the incident infrared light, and transmits the second wavelength band. And a two-wavelength separation optical system including a reflecting mirror that changes the optical path by receiving the first wavelength band; a first infrared detector that receives the infrared light from the reflecting mirror, guides it to an infrared sensor, and converts it into an electric signal A second infrared detector that receives transmitted light from the filter, guides it to an infrared sensor, and converts it into an electric signal; the condensing optical system, the two-wavelength separation optical system, the first and second infrared rays A gimbal that combines detectors and mounts them together 2, characterized by being provided with a
Provided is a two-wavelength infrared image homing device with a wavelength separation optical system.

According to the present invention, by the above means, the condensing optical system common to two wavelengths is designed to reflect the first wavelength band, for example, the long wavelength band, and transmit the second wavelength band, for example, the long wavelength band. Since it is efficiently separated into two wavelengths by the two-wavelength separation optical system including the filter and the reflecting mirror, it is possible to realize an appropriate aperture diameter which is not so large as compared with the case of only one wavelength.

Further, by adopting a Cassegrain type reflecting mirror consisting of a main mirror and a sub mirror in the condensing optical system for two wavelengths, not only the length of the optical system is shortened as compared with the focal length, but also the sub mirror. It is possible to arrange a filter for separating the two wavelengths and a reflecting mirror that returns the optical path reflected by the filter in the optical axis direction between the main mirror and the sub mirror by tilting with respect to the optical axis. Can realize a reasonable total length of the optical system that is less than or equal to the focal length.

Furthermore, after the two wavelengths are separated, without directly forming an image,
Since the parallel incident light to the condensing optical system can be converted into the parallel light again by the relay lens, the incident light can be intersected with the cold shield opening, and the aperture matching can be realized by the imaging lens arranged there. .

It is possible to reduce the size and weight of the imager by integrally combining the condensing optical system, the two-wavelength separating optical system, and the first and second infrared detectors. It is possible to realize a dual wavelength infrared image homing device that can be installed in a vehicle and mounted on a flying object.

[0012]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a cross-sectional view of a dual wavelength infrared imager of a dual wavelength infrared image homing apparatus using a dual wavelength separation optical system according to an embodiment of the present invention.

In the figure, a dual wavelength infrared imager 10 is shown.
Is composed of a two-wavelength separation optical system 1, a long-wavelength infrared detector 2 and a medium-wavelength infrared detector 3, and a narrow one is a primary mirror 1a as a Cassegrain type two-wavelength common condensing optical system,
Secondary mirror 1b, mid-wavelength band transmission type infrared filter 1c as a wavelength separation optical system, reflecting mirror 1d, relay lenses 1e and 1f for each wavelength band, and vacuum containers 2a and 3 as infrared ray detectors.
a, imaging lenses 2b and 3b, two-dimensional infrared sensors 2c and 3c, and coolers 2d and 3d.

In the two-wavelength infrared imager 10 having such a structure, the incident infrared ray R from the target scene which has entered the primary mirror 1a is reflected by the secondary mirror 1b which is attached at an angle with respect to the optical axis of the primary mirror 1a. Before focusing on the Cassegrain focus, the infrared ray R _{1 in the} long wavelength band is reflected by the filter 1c and the infrared ray R ₂ in the medium wavelength band is transmitted,
Can be efficiently separated into two wavelengths.

The infrared ray R _{1 in the} long wavelength band is further reflected by the reflecting mirror 1d.
Then, it is bent in the optical axis direction as indicated by reference numeral R ₃ . The infrared light focused once after being reflected or transmitted by the filter 1c is converted into parallel light again by the relay lens 1e for the long wavelength band and the relay lens 1f for the medium wavelength band placed on the way of divergence. Is guided to an imaging lens 2b or 3b arranged in the cold shield opening of the detector,
An image is formed on the two-dimensional infrared sensor 2c or 3c and converted into an electric signal.

It should be noted that the infrared incident light from the visual field center and the visual field end shown in FIG. 1 just intersect at the cold shield opening having the imaging lens 2b or 3b and can be imaged at the center and the edge of the two-dimensional infrared sensor. Therefore, aperture matching can also be realized with this structure.

Here, since the loss of the amount of incident light and the loss of the amount of transmitted light or the amount of reflected light by the filter due to the sub-mirror 1b blocking a part of the main mirror 1a are considerably small, an appropriate aperture diameter can be realized even if the amount is considered. . An example of trial calculation of the opening diameter in consideration of such a loss will be described below.

If the shielding loss by the secondary mirror 1b is about 10% and the filter 1c is a multi-layer interference filter which is generally used at present and the transmission loss is about 20% (the reflection loss is about 10%), the condensing optics is The incident light quantity by the system may be about 1 / (1-0.1-0.2) ≈ 1.4 times that in the case of only one wavelength. Since the incident light quantity is proportional to the square of the aperture diameter, Can be realized with a size of about √1.4≈1.2 times that of the case of only one wavelength.

In the above embodiment, the filter 1c is of a medium wavelength band transmissive type in the case of a high sensitivity quantum infrared sensor, and the longer one of the wavelength bands used depends on the characteristics of the infrared sensor itself. Although the cut-off wavelength is naturally limited, the shorter one has no cut-off characteristic, so that it is usually required to be limited by the filter 1c. So 2
This is because the filter for wavelength separation is also used as the short wavelength cut filter 1c for the detector in the long wavelength band so that the number of extra optical elements is not increased as much as possible.

To eliminate the slight inclination of the detector 3 for the medium wavelength with respect to the optical axis, the shape of the filter may be formed into a prism, or the main mirror may be tilted so that the position of the secondary mirror is off the optical axis. Although it is possible to make them parallel, they are not used in this embodiment because they have a bad influence on the optical characteristics.

As described above, the two-wavelength infrared imager 10 according to the present embodiment can realize an appropriate aperture diameter because the loss is considerably small even if the primary mirror 1a and the secondary mirror 1b are used, and the Cassegrain is shorter than the focal length. A two-wavelength separation optical system can be realized with a length of a type optical system.

The shape of this imager is highly axisymmetric, and the unbalanced moment increase is small.
Further, in the conventional refracting optical system, the lens is heavy and the head is considerably heavy with respect to the support center (near the sensor surface), whereas the Cassegrain type optical system causes the whole center of gravity to come near the support center. Further, since the weight of the optical system can be lighter in the reflection system than in the refraction system, the weight increase will be small even if the number of detectors is increased to two. Due to these advantages, when the imager 10 is mounted on the gimbal mechanism, Since the influence on the gimbal ability to mount the device is small, the dual wavelength infrared image homing device can be sufficiently realized by such an imager 10.

FIG. 2 shows the dual wavelength infrared imager 10 described above.
FIG. 3 is a perspective view of a two-wavelength infrared image homing apparatus having a two-wavelength separation optical system mounted on the gimbal 12. In the figure, the two-wavelength infrared imager 10 is the primary mirror 1 as described above.
a, a secondary mirror 1b, a filter 1c for separating two wavelengths from infrared rays from them, a reflecting mirror 1d, a relay lens 1e, 1
f, a long-wavelength infrared detector 2 and a medium-wavelength infrared detector 3, which are mounted on the gimbal 12 and are entirely infrared dome 1
Covered with 1.

As described above, in the above embodiment, the Cassegrain-type condensing optical system for two wavelengths, which is composed of the primary mirror 1a and the secondary mirror 1b tilted with respect to the optical axis thereof, and the primary mirror 1a. A two-wavelength separation optical system including a filter 1c arranged between the sub-mirrors 1b, a reflecting mirror 1d, and two sets of relay lenses 1e and 1f, and two wavelengths each including imaging lenses 2b and 3b in the cold shield opening. The infrared detectors 2 and 3 are integrated into an infrared imager 10 which is miniaturized and mounted on the gimbal 12 so that a two-wavelength infrared image homing device for a flying object can be realized.

[0025]

As described above in detail, the present invention, as a two-wavelength imager, has a common-wavelength condensing optical system including a main mirror and a sub-mirror, and is disposed between the main mirror and the sub-mirror. Two-wavelength separation optical system consisting of a filter and a reflecting mirror, and
Since the infrared detectors for each wavelength are assembled together as an integrated structure, it is possible to realize a reasonable aperture diameter and optical system length for mounting the gimbal, and it is possible to mount a small imager on the gimbal. A dual wavelength infrared image homing device can be realized.

[Brief description of the drawings]

FIG. 1 is applied to a dual-wavelength infrared image homing apparatus having a dual-wavelength separation optical system according to an embodiment of the present invention.
It is sectional drawing of a wavelength infrared imager.

FIG. 2 is a perspective view of a two-wavelength infrared image homing apparatus including a two-wavelength separation optical system according to an embodiment of the present invention.

FIG. 3 is a configuration diagram of a conventional one-wavelength infrared imager.

[Explanation of symbols]

 1 2 Wavelength separation optical system 1a Main mirror 1b Sub mirror 1c Infrared filter 1d Reflecting mirror 1e, 1f Relay lens 2 Long wavelength infrared detector 2a, 3a Vacuum container 2b, 3b Imaging lens 2c, 3c Two-dimensional infrared sensor 2d, 3d Cooler 3 Medium wavelength infrared detector 10 2 wavelength infrared imager 11 Infrared 12 Gimbal

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location // G05D 1/12 H01L 31/02 E

Claims (1)

[Claims] 1. A condensing optical system including a main mirror that receives and reflects infrared rays, and a secondary mirror that receives the infrared rays reflected from the main mirror and reflects in the optical axis direction; a main mirror of the condensing optical system. Is disposed between the secondary mirror and the secondary mirror, receives the first wavelength band of the infrared ray that is reflected from the secondary mirror and reflects the first wavelength band of the incident infrared ray, and receives the first wavelength band. A two-wavelength separation optical system consisting of a reflecting mirror for changing the optical path; a first infrared detector for receiving infrared rays from the reflecting mirror and guiding it to an infrared sensor and converting it into an electric signal; receiving transmitted light from the filter A second infrared detector that guides the light to an infrared sensor and converts it into an electric signal; combining the condensing optical system, the two-wavelength separation optical system, and the first and second infrared detectors integrally, It is characterized by comprising a gimbal for mounting these 2 Dual wavelength infrared image homing device with wavelength separation optical system.