CN111007659B - Multi-band confocal plane infrared optical imaging system - Google Patents
Multi-band confocal plane infrared optical imaging system Download PDFInfo
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- CN111007659B CN111007659B CN201911335559.9A CN201911335559A CN111007659B CN 111007659 B CN111007659 B CN 111007659B CN 201911335559 A CN201911335559 A CN 201911335559A CN 111007659 B CN111007659 B CN 111007659B
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- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B17/00—Systems with reflecting surfaces, with or without refracting elements
- G02B17/08—Catadioptric systems
- G02B17/0804—Catadioptric systems using two curved mirrors
- G02B17/0808—Catadioptric systems using two curved mirrors on-axis systems with at least one of the mirrors having a central aperture
Abstract
The invention provides a multiband confocal plane infrared optical imaging system, and relates to the technical field of infrared detection. The multiband confocal plane infrared optical imaging system comprises a reflector group, a lens group and an infrared detector, wherein all optical elements are arranged on the same optical axis, the reflector group, the lens group and the infrared detector are sequentially arranged along the optical axis from an object space to an image space, a light beam is reflected by a primary mirror and then incident on a secondary mirror, the secondary mirror reflects, focuses and images on a first image surface, the lens group converts an object on the first image surface into an image and focuses on a second image surface, and the second image surface is superposed with a focal plane array; the spectrum transmission range of the optical imaging system is 2.5-9.5 microns, and the optical imaging system can simultaneously image short-wave infrared, medium-wave infrared and long-wave infrared. The multiband confocal plane infrared optical imaging system avoids energy loss caused by adopting light splitting elements in the traditional infrared optical imaging systems with more than two bands, optimizes the system structure, enables the imaging quality to be close to the diffraction limit and has stable performance.
Description
Technical Field
The invention relates to the technical field of infrared detection, in particular to a multiband confocal plane infrared optical imaging system.
Background
In the fields of aerospace, aviation, military and scientific detection, the requirements on indexes such as the caliber, the view field, the wave band and the like of an infrared optical system are higher and higher, the infrared optical system mainly has three optical types of a reflection type, a refraction type and a refraction and reflection type, and the caliber of the refraction type system is usually difficult to exceed 200mm due to the limitations of processing, uniformity and the like of a transmission material; the imaging field of view of the reflective system is generally small, and the available field of view is usually within 1 degree; the refraction and reflection type optical imaging system is additionally provided with a refraction element on the basis of a reflection type optical imaging system, and aberration optimization parameters are increased, so that the optical system has a large caliber and a large field of view.
In addition, the atmospheric windows are distributed in three wave band ranges of near infrared of 0.75-2.5 micrometers, medium wave infrared of 3-5 micrometers and long wave infrared of 8-14 micrometers. By combining the imaging characteristics of each waveband, the infrared optical system working in multiband can acquire sufficient and useful information, can avoid the limitation of acquiring information by a single waveband infrared system, and plays an important role in target detection and identification.
Due to the problems of transmission materials and design types, when the operating wavelength band of the existing catadioptric infrared optical imaging system is more than two, a beam splitting element is usually adopted behind a lens for splitting, and the adoption of the beam splitting element has the following influence on the optical system: one is the loss of incident energy and the other is the added complexity of the system. In order to solve the above problems, there is an urgent need to research a multiband confocal plane infrared optical system, which simplifies the structure of the system, avoids energy loss, and has multiple working bands and good imaging quality.
Disclosure of Invention
The invention aims to provide a multiband confocal plane infrared optical imaging system aiming at the defects in the prior art, which can simultaneously image short-wave infrared, medium-wave infrared and long-wave infrared to avoid the limitation of a single-wave-band infrared system in acquiring information, avoid energy loss caused by adopting a light splitting element in the traditional infrared optical imaging systems with more than two bands and optimize the system structure.
The object of the invention can be achieved by the following technical measures:
the invention provides a multiband confocal plane infrared optical imaging system, all optical elements are arranged on the same optical axis, a reflector group, a lens group and an infrared detector are sequentially arranged from an object space to an image space along the optical axis,
the reflector group comprises a primary mirror and a secondary mirror, the reflecting surface of the primary mirror and the reflecting surface of the secondary mirror are oppositely arranged, and the primary mirror is provided with a central hole;
the infrared detector is a refrigeration type detector and comprises a window, an optical filter and a focal plane array, and the lens group is positioned between the first image plane and the infrared detector;
the light beam is reflected by the primary mirror and then enters the secondary mirror, the secondary mirror reflects, focuses and images on the first image surface, the lens group rotates and focuses a target on the first image surface on a second image surface, and the second image surface is superposed with the focal plane array;
the spectrum transmission range of the optical imaging system is 2.5-9.5 microns, and the optical imaging system can simultaneously image short-wave infrared, medium-wave infrared and long-wave infrared.
Further, the lens group comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens which are arranged in sequence along the same optical axis, and the surfaces of the lenses are spherical.
Furthermore, the first lens is IRG24 infrared glass, the front surface is a concave spherical surface, and the rear surface is a convex spherical surface.
Further, the second lens is made of ZnS crystal material, the front surface of the second lens is a convex spherical surface, and the rear surface of the second lens is a concave spherical surface.
Furthermore, the third lens is IRG24 infrared glass, and the front surface and the rear surface are both convex spherical surfaces.
Furthermore, the fourth lens is made of Ge crystal material, the front surface of the fourth lens is a concave spherical surface, and the rear surface of the fourth lens is a concave spherical surface.
Furthermore, the fifth lens is IRG24 infrared glass, the front surface is a convex spherical surface, and the rear surface is a concave spherical surface.
Furthermore, the primary mirror is a concave aspheric mirror, and the reflecting surface is a standard quadric surface or a high-order aspheric surface;
the secondary mirror is a convex aspheric mirror, and the reflecting surface is a standard quadric surface or a high-order aspheric surface.
Furthermore, the primary mirror and the secondary mirror are made of any one of aluminum, silicon carbide, beryllium aluminum and microcrystalline glass.
Furthermore, the window is made of Ge or ZnSe and can transmit infrared beams; the filter is used as a cold stop placed between the window and the focal plane array.
The multiband confocal plane infrared optical imaging system has the beneficial effects that:
1) multiple working wave bands
The working waveband of the multiband confocal plane infrared optical system is as follows: short wave infrared 2.5-2.9 micron, medium wave infrared 3.7-4.8 micron and long wave infrared 7.7-9.5 micron, and this can avoid the limitation of single wave band infrared system in obtaining information and raise information obtaining amount and target identifying rate.
2) Good fitting performance
All optical elements in the multiband confocal plane infrared optical system are arranged on the same optical axis, parts in an optical path are all fixed parts, the installation and adjustment are simple, and the installation and adjustment difficulty of the system is reduced to a great extent.
3) The imaging quality is good
According to the invention, through optimizing optical materials and reasonably optimizing a system, the design of the confocal plane of three wave bands is realized, the energy loss caused by the realization of multi-wave bands of the traditional light splitting element is avoided, the imaging quality is close to the diffraction limit, and the performance is stable.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic diagram of a multiband confocal plane infrared optical imaging system of the present invention;
FIG. 2 is an MTF curve of the multiband confocal plane infrared optical imaging system of an embodiment of the present invention at a short band of 2.5 μm to 2.9 μm;
FIG. 3 is an MTF curve of the multiband confocal plane infrared optical imaging system of an embodiment of the present invention at the middle band of 3.7 μm to 4.8 μm;
FIG. 4 is a MTF curve of the multiband confocal plane infrared optical imaging system of one embodiment of the present invention in the long wavelength band of 7.7 μm to 9.5 μm;
FIG. 5 is a color focus shift curve of a multi-band confocal plane infrared optical imaging system in short, medium, and long wavelength bands according to an embodiment of the present invention;
description of the drawings: 1-a reflector group, 11-a primary mirror, 12-a secondary mirror and 13-a primary image plane; 2-lens group, 21-first lens, 22-second lens, 23-third lens, 24-fourth lens, 25-fifth lens; 3-infrared detector, 31-window, 32-optical filter, 33-focal plane array.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.
In order to make the description of the present disclosure more complete and complete, the following description is given for illustrative purposes with respect to the embodiments and examples of the present invention; it is not intended to be the only form in which the embodiments of the invention may be practiced or utilized. The embodiments are intended to cover the features of the various embodiments as well as the method steps and sequences for constructing and operating the embodiments. However, other embodiments may be utilized to achieve the same or equivalent functions and step sequences.
Referring to fig. 1, which is a schematic structural diagram of the multiband confocal plane infrared optical imaging system of the present invention, all optical elements of the multiband confocal plane infrared optical imaging system of the present invention are arranged on the same optical axis, and a reflector group 1, a lens group 2 and an infrared detector 3 are sequentially arranged from an object side to an image side along the optical axis.
The reflector group 1 comprises a primary mirror 11 and a secondary mirror 12, wherein the reflecting surface of the primary mirror 11 and the reflecting surface of the secondary mirror 12 are oppositely arranged, and a central hole is formed in the primary mirror 11.
In some embodiments, the primary mirror 11 can be selected to be a concave aspheric mirror, and the reflecting surface is a standard quadric surface or a high-order aspheric surface; the secondary mirror 12 can be selected as a convex aspheric mirror, and the reflecting surface is a standard quadric surface or a high-order aspheric surface. As for the selection of materials, the materials of the primary mirror 11 and the secondary mirror 12 may be selected from aluminum, silicon carbide, beryllium aluminum, microcrystalline glass, and the like.
The infrared detector 3 is a refrigeration type detector and comprises a window 31, an optical filter 32 and a focal plane array 33, and the lens group 2 is located between the first image plane 13 and the infrared detector 3.
The material of the window 31 may be selected from an infrared transmitting material such as Ge or ZnSe, and is used for transmitting an infrared light beam. The filter 32 is arranged as a cold stop between the window 31 and the focal plane array 33 to determine the solid angle at which the focal plane array 33 receives the target radiation, suppressing stray light reaching the focal plane array 33; meanwhile, the cold stop is used as the exit pupil of the optical system, and the entrance pupil of the object space and the conjugate thereof is superposed with the main mirror 11 as much as possible, so that the aperture of the main mirror 11 can be effectively reduced.
The light beam is incident on the secondary mirror 12 after being reflected by the primary mirror 11, the secondary mirror 12 reflects, focuses and images on the first image plane 13, the lens group 2 transfers images of a target on the first image plane 13 and focuses on the second image plane, and the second image plane coincides with the focal plane array 33.
In some embodiments, the lens group 2 includes a first lens 21, a second lens 22, a third lens 23, a fourth lens 24 and a fifth lens 25, which are sequentially disposed along the same optical axis, and all surfaces are spherical. The first lens 21 is IRG24 infrared glass, the front surface is a concave spherical surface, and the rear surface is a convex spherical surface; the second lens 22 is made of ZnS crystal material, the front surface of the second lens is a convex spherical surface, and the rear surface of the second lens is a concave spherical surface; the third lens 23 is IRG24 infrared glass, and the front surface and the rear surface are both convex spherical surfaces; the fourth lens 24 is made of Ge crystal material, the front surface of the fourth lens is a concave spherical surface, and the rear surface of the fourth lens is a concave spherical surface; the fifth lens 25 is made of IRG24 infrared glass, the front surface of the fifth lens is a convex spherical surface, and the rear surface of the fifth lens is a concave spherical surface. Wherein IRG24 is an infrared optical glass of Germany Schottky company, and the component is Ge10As40Se50The glass is also germanium arsenic selenium glass, the transmission waveband is 0.8-15.5 mu m, the glass is called IRG207 in Xinhua optical information material Limited in Hubei, and is called HWS5 in Duguang.
Of course, the present invention is not limited to the above-described embodiments, and other types and materials of the primary mirror 11, the secondary mirror 12, the first lens 21, the second lens 22, the third lens 23, the fourth lens 24, and the fifth lens 25 may be used.
The spectrum transmission range of the multiband confocal plane infrared optical imaging system is 2.5-9.5 micrometers, and short-wave infrared, medium-wave infrared and long-wave infrared can be imaged simultaneously.
Example 1
The technical indexes of the system are as follows:
focal length: 146.5 mm;
relative pore diameter: 1: 2;
visual field: 3 ° × 3 °;
the number of detector pixels is as follows: 256 × 256;
pixel size: 30 mu m;
the working wave band is as follows: short wave infrared 2.5-2.9 micron; medium wave infrared 3.7-4.8 micron; long wave infrared 7.7-9.5 micron.
The optical element parameters of the multiband confocal plane infrared optical imaging system of the embodiment are shown in table 1.
TABLE 1 optical element parameter design Table
As shown in fig. 2-5, for the MTF curve and the color focus shift curve of the multiband confocal plane infrared optical imaging system of this embodiment in the short, medium, and long wavelength bands, the optical transfer function is: the MTF of the edge field is more than 0.65 when the short wave infrared is 2.5-2.9 mu m and the space frequency is 17 lp/mm; the MTF of the edge field is more than 0.58 when the medium wave infrared is 3.7-4.8 mu m and the space frequency is 17 lp/mm; the MTF of the edge field is more than 0.3 when the long wave infrared is 7.7-9.5 mu m and the space frequency is 17 lp/mm. The multiband confocal plane infrared optical imaging system has the advantages that the transfer function is close to the diffraction limit, the cold stop matching reaches 100%, and the imaging quality is good.
The multiband confocal plane infrared optical imaging system has the beneficial effects that:
1) multiple working wave bands
The working waveband of the multiband confocal plane infrared optical system is as follows: short wave infrared 2.5-2.9 micron, medium wave infrared 3.7-4.8 micron and long wave infrared 7.7-9.5 micron, and this can avoid the limitation of single wave band infrared system in obtaining information and raise information obtaining amount and target identifying rate.
2) Good fitting performance
All optical elements in the multiband confocal plane infrared optical system are arranged on the same optical axis, parts in an optical path are all fixed parts, the installation and adjustment are simple, and the installation and adjustment difficulty of the system is reduced to a great extent.
3) The imaging quality is good
According to the invention, through optimizing optical materials and reasonably optimizing a system, the design of the confocal plane of three wave bands is realized, the energy loss caused by the realization of multi-wave bands of the traditional light splitting element is avoided, the imaging quality is close to the diffraction limit, and the performance is stable.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (4)
1. A multiband confocal plane infrared optical imaging system is provided, all optical elements are arranged on the same optical axis, and a reflector group, a lens group and an infrared detector are arranged in sequence from an object side to an image side along the optical axis,
the reflector group consists of a primary mirror and a secondary mirror, the reflecting surface of the primary mirror and the reflecting surface of the secondary mirror are oppositely arranged, and the primary mirror is provided with a central hole;
the infrared detector is a refrigeration type detector and comprises a window, an optical filter and a focal plane array, and the lens group is positioned between the first image plane and the infrared detector;
the light beam is reflected by the primary mirror and then enters the secondary mirror, the secondary mirror reflects, focuses and images on the first image surface, the lens group rotates and focuses a target on the first image surface on a second image surface, and the second image surface is superposed with the focal plane array;
the spectrum transmission range of the optical imaging system is 2.5-9.5 microns, and short-wave infrared, medium-wave infrared and long-wave infrared can be imaged simultaneously;
the lens group consists of a first lens, a second lens, a third lens, a fourth lens and a fifth lens which are sequentially arranged along the same optical axis, and the surfaces of the lens group are spherical surfaces;
the first lens is IRG24 infrared glass, the front surface is a concave spherical surface, and the rear surface is a convex spherical surface;
the second lens is made of ZnS crystal material, the front surface of the second lens is a convex spherical surface, and the rear surface of the second lens is a concave spherical surface;
the third lens is IRG24 infrared glass, and the front surface and the rear surface are both convex spherical surfaces;
the fourth lens is made of Ge crystal material, the front surface of the fourth lens is a concave spherical surface, and the rear surface of the fourth lens is a concave spherical surface;
the fifth lens is IRG24 infrared glass, the front surface of the fifth lens is a convex spherical surface, and the rear surface of the fifth lens is a concave spherical surface.
2. The multiband confocal surface infrared optical imaging system of claim 1, wherein the primary mirror is a concave aspheric mirror, and the reflecting surface is a standard quadric or high order aspheric surface;
the secondary mirror is a convex aspheric mirror, and the reflecting surface is a standard quadric surface or a high-order aspheric surface.
3. The system of claim 1, wherein the primary and secondary mirrors are made of any one of aluminum, silicon carbide, beryllium aluminum, and glass-ceramic.
4. The multiband confocal surface infrared optical imaging system of claim 1, wherein the window is made of Ge or ZnSe and is transparent to infrared light; the filter is used as a cold stop placed between the window and the focal plane array.
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| CN114415358B (en) * | 2021-12-18 | 2023-02-21 | 中国科学院长春光学精密机械与物理研究所 | Catadioptric optical system |
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| CN100580499C (en) * | 2007-11-21 | 2010-01-13 | 中国科学院上海技术物理研究所 | Refraction-reflection type dual-waveband imaging telescope optical system |
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