CN115755337A - Infrared scanning optical system with ultra-large field of view - Google Patents
Infrared scanning optical system with ultra-large field of view Download PDFInfo
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- CN115755337A CN115755337A CN202211357405.1A CN202211357405A CN115755337A CN 115755337 A CN115755337 A CN 115755337A CN 202211357405 A CN202211357405 A CN 202211357405A CN 115755337 A CN115755337 A CN 115755337A
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Abstract
The invention relates to an infrared scanning optical system with an ultra-large view field, belonging to the technical field of detection and investigation; the device comprises a first objective lens, a second objective lens, a third objective lens, a fourth objective lens, a Pechan prism, a fifth objective lens, a sixth objective lens, a seventh objective lens and a detector; the first objective lens, the second objective lens, the third objective lens, the fourth objective lens and the Pechan prism are sequentially and coaxially arranged along a first optical axis direction, and the first optical axis and a system optical axis are arranged; the fifth objective lens, the sixth objective lens, the seventh objective lens and the detector are sequentially and coaxially arranged behind the Pechan prism along a second optical axis direction; the second optical axis direction and the first optical axis direction are offset in the two directions of x and y which are perpendicular to each other, and the offset is the half-image height size of the detector, namely the offset in the x direction: x = H detector /2,y Direction offset: y = V detector /2 wherein H detector Representing detector image plane length, V detector Representing the detector image plane width. The invention adopts step staring scanning of the Pechan prism to obtain image pictures with higher resolution and larger picture through multi-frame video splicing.
Description
Technical Field
The invention belongs to the technical field of detection and investigation, and particularly relates to an infrared scanning optical system with an ultra-large view field.
Background
The infrared detection alarm system is a high-efficiency modern reconnaissance means, is widely popularized in military and civil use, and still has very strong detection capability and accurate positioning capability particularly under the conditions of severe natural environment and interference of other systems. For the detection and investigation field, the method can work as situation awareness and passive alarm, and mainly provides detection positioning and threat awareness capabilities of scene targets. The method has imaging performance and can be used for day and night scene navigation or visual judgment.
In order to improve the detection and alarm capabilities, the infrared detection alarm system needs to obtain a wider detection field of view and a higher resolution picture image. The main methods for improving the detection capability at present are as follows: and designing a larger-scale infrared integral detector with higher resolution to be matched with the optical system so as to obtain a higher-definition detection image. The high-resolution infrared detector is very expensive, so that the development cost of the system is greatly increased; and the volume and weight of the optical system can be greatly increased by selecting a larger area array infrared detector, and difficulty is brought to the application of the airborne warning platform with higher requirement on the space size.
Disclosure of Invention
The technical problem to be solved is as follows:
in order to avoid the defects of the prior art, the invention provides an infrared scanning optical system with an ultra-large view field, which is a compact large view field alarm optical system and adopts a technical scheme of improving the alarm resolution and the detection performance under the condition of limited detector cost. The invention adopts the light path design with large field of view and partial offset, adopts the step staring scanning of the Pechan prism, and obtains the image picture with higher resolution and larger picture by multi-frame video splicing. The purposes of reducing development cost and improving detection performance of the system are achieved.
The technical scheme of the invention is as follows: an infrared scanning optical system with an ultra-large field of view comprises a first objective lens, a second objective lens, a third objective lens, a fourth objective lens, a Pechan prism, a fifth objective lens, a sixth objective lens, a seventh objective lens and a detector; the first objective lens, the second objective lens, the third objective lens, the fourth objective lens and the Pechan prism are sequentially and coaxially arranged along a first optical axis direction, and the first optical axis and a system optical axis are arranged; the fifth objective lens, the sixth objective lens, the seventh objective lens and the detector are sequentially and coaxially arranged behind the Pechan prism along a second optical axis direction;
the second optical axis direction and the first optical axis direction are offset in the two directions of x and y which are perpendicular to each other, and the offset is the half-image height size of the detector, namely the offset in the x direction: x = H detector /2,y Direction offset: y = V detector /2 wherein H detector Representing detector image plane length, V detector Representing the detector image plane width.
The further technical scheme of the invention is as follows: the central axis of the first objective lens is coaxial with the first optical axis, the focal length of the first objective lens is 48.4mm, the clear aperture is 18mm, the curvature radius of the front surface is-37.32, the curvature radius of the rear surface is-31.968, and the first objective lens is made of monocrystalline silicon;
the distance between the second objective lens and the first objective lens is 2.16mm, the focal length is-104.7 mm, the light transmission aperture is 25mm, the front surface curvature radius 61.848 and the rear surface curvature radius 37.21 are made of monocrystalline silicon;
the distance between the third objective lens and the second objective lens is 19.38mm, the focal length is 96.3mm, the light transmission aperture is 23mm, the curvature radius of the front surface is-44.869, the curvature radius of the rear surface is-49.45, and the third objective lens and the second objective lens are made of monocrystalline silicon;
the distance between the fourth objective lens and the third objective lens is 11.23mm, the focal length is 88.3mm, the clear aperture is 35.1mm, the curvature radius of the front surface is-90.765, the curvature radius of the rear surface is-76.423, and the material of the fourth objective lens is single crystal germanium;
the distance between the Pechan prism and the fourth objective is 10mm, and the aperture of the light passing through the Pechan prism is 45 multiplied by 45mm 2 The material is zinc sulfide or monocrystalline silicon.
The further technical scheme of the invention is as follows: the Pechan prism rotates 45 degrees, 90 degrees, 135 degrees and 180 degrees along the optical axis of the system in sequence; the rotational scanning of the Pechan prism realizes the imaging offset of an optical primary imaging surface, further realizes the spatial view field conversion of the Pechan prism in different scanning position systems, 4 frames of images obtained by 4 times of rotation are spliced to obtain single-frame 60-degree original images, and the scanning circular view field can exceed 110 degrees after splicing.
The further technical scheme of the invention is as follows: and the central axis of the fifth objective lens is coaxial with the second optical axis and is offset by 8mm in the horizontal direction and the vertical direction respectively.
The further technical scheme of the invention is as follows: the center distance between the fifth objective lens and the Pechan prism is 10mm, the clear aperture is 22.5mm, the focal length is-34.8 mm, the curvature radius of the front surface is-108.728, the curvature radius of the rear surface is 127.994, and the fifth objective lens is made of chalcogenide glass IRG206;
the distance between the sixth objective lens and the fifth objective lens is 1.7mm, the clear aperture is 18.8mm, the focal length is 24.58mm, the curvature radius of the front surface is 69.6469, the curvature radius of the rear surface is 1327.27, and the material of the sixth objective lens is monocrystalline germanium;
the distance between the seventh objective lens and the sixth objective lens is 14mm, the clear aperture is 18.6mm, the focal length is-37.6 mm, the curvature radius of the front surface is-135.568, the curvature radius of the rear surface is 269.599, and the material of the seventh objective lens is monocrystalline silicon.
The invention further adopts the technical scheme that: the distance between the detector and the seventh objective lens is 4mm, and the detector is a refrigeration type infrared detector or a non-refrigeration type infrared detector.
The further technical scheme of the invention is as follows: the size ratio of the length H to the width V of the image surface of the detector is 6:4 or 16, and the material of the image surface is mercury cadmium telluride or indium antimonide.
The invention further adopts the technical scheme that: the working mode of the detector is scanning staring, the working frame frequency of the detector is consistent with the scanning frame frequency of the Pechan prism, and the detection integration time is the same as the staying time of the Pechan prism at the scanning position.
The further technical scheme of the invention is as follows: the detector size is 16mm x 16mm.
The invention further adopts the technical scheme that: the focal length F =38mm of the optical system, the scanning field angle is larger than or equal to 90 degrees multiplied by 90 degrees, the F number is 2, and the working waveband is 3-5 μm.
Advantageous effects
The invention has the beneficial effects that: the ultra-large visual field infrared scanning optical system can be applied to the fields of police security, military infrared alarm, investigation and the like. The method has the advantages of large detection field range, high resolution and small occupied space of scanning envelope. The method can effectively improve the detection resolution of a resolution limited system, increase the visible distance, enlarge the detection range and enhance the target recognition capability.
1. The invention only adopts 7 lenses to realize the design, the instantaneous field angle is more than or equal to 60 degrees, the scanning field angle is more than or equal to 110 degrees, and the total length of the system is less than or equal to 300mm.
2. The invention is applied to infrared super wide angle monitoring photoelectric products, and improves the optical resolution of the full view field by one time and the scanning view field by one time compared with the prior art.
3. The prism offset scanning mode designed by the invention can compress the axial volume by more than one third, thereby expanding the application scene of the system and meeting the miniaturization requirement of products.
Drawings
FIG. 1 is a diagram of an ultra-large field of view infrared scanning optical system of the present invention.
FIG. 2 is a graph of transfer function MTF of the ultra-large field of view infrared scanning optics of the present invention.
FIG. 3 is a dot-column diagram of the ultra-large field-of-view infrared scanning optics of the present invention.
Description of reference numerals: 1. the device comprises a first objective lens, a second objective lens, a third objective lens, a fourth objective lens, a Biehan prism, a fifth objective lens, a sixth objective lens, a seventh objective lens and a detector, wherein the first objective lens, the second objective lens, the third objective lens, the fourth objective lens, the second objective lens, the fourth objective lens, the Biehan prism, the fifth objective lens, the sixth objective lens, the seventh objective lens and the detector are arranged in sequence.
Detailed Description
The embodiments described below with reference to the accompanying drawings are illustrative and intended to explain the present invention and should not be construed as limiting the present invention.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations or positional relationships based on those shown in the drawings, merely for convenience of description and simplification of the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, are not to be construed as limiting the present invention.
As shown in fig. 1, the specific parameters of the long-focus large-field infrared search tracking optical system in this embodiment are as follows:
(I) optical system
Focal length f =38mm;
f number 2;
the scanning field of view is more than or equal to 110 degrees.
(II) Infrared detector
Pixel size: 15 μm
Effective pixel: 2048H × 2048V
(III) working wave band: 3-5 μm
The ultra-large visual field infrared scanning optical system comprises a first objective lens 1, a second objective lens 2, a third objective lens 3, a fourth objective lens 4, a Pechan prism 5, a fifth objective lens 6, a sixth objective lens 7, a seventh objective lens 8 and a detector 9. The optical elements of the first objective lens 1, the second objective lens 2, the third objective lens 3, the fourth objective lens 4 and the Pechan prism 5 are sequentially and coaxially arranged, the fifth objective lens 6, the sixth objective lens 7, the seventh objective lens 8 and the detector 9 are sequentially arranged behind the Pechan prism 5 along the optical axis direction, and offset is in two directions of x and y perpendicular to the optical axis, and the offset is a half-image height size of the detector 9, namely offset in the x direction: x = l detector /2,y Direction offset: y = h detector /2。
The specific parameters of the optical system are as follows:
the central axis of the first objective lens 1 is coaxial with the optical axis of the system, the focal length is 48.4mm, the light transmission aperture is 18mm, the curvature radius of the front surface is-37.32, the curvature radius of the rear surface is-31.968, and the material of the first objective lens is monocrystalline silicon.
The central axis of the second objective lens 2 is coaxial with the optical axis of the system, the distance between the central axis of the second objective lens 2 and the first objective lens 1 is 2.16mm, the focal length is-104.7 mm, the clear aperture is 25mm, the curvature radius of the front surface is 61.848, the curvature radius of the rear surface is 37.21, and the material of the second objective lens is monocrystalline silicon.
The central axis of the third objective lens 3 is coaxial with the optical axis of the system, the distance between the central axis and the second objective lens 2 is 19.38mm, the focal length is 96.3mm, the clear aperture is 23mm, the curvature radius of the front surface is-44.869, the curvature radius of the rear surface is-49.45, and the material of the third objective lens is monocrystalline silicon.
The central axis of the fourth objective lens 4 is coaxial with the optical axis of the system, the distance between the central axis and the third objective lens 3 is 11.23mm, the focal length is 88.3mm, the clear aperture is 35.1mm, the curvature radius of the front surface is-90.765, the curvature radius of the rear surface is-76.423, and the material of the fourth objective lens is single crystal germanium.
The central shaft of the Pechan prism 5 is coaxial with the optical axis of the system, the distance between the central shaft and the fourth lens 4 is 10mm, and the light-passing aperture is 45 multiplied by 45mm 2 The material is monocrystalline silicon.
The Pechan prism 5 rotates 45 degrees, 90 degrees, 135 degrees and 180 degrees along the optical axis of the system in sequence; the rotational scanning of the Pechan prism realizes the imaging offset of an optical primary imaging surface, further realizes the spatial view field conversion of the Pechan prism in different scanning position systems, 4 frames of images obtained by 4 times of rotation are spliced to obtain a single frame of original images with 60 degrees, and the scanning circular view field can exceed 110 degrees after splicing.
The center distance between the fifth objective lens 6 and the Pechan prism 5 is 10mm, the clear aperture is 22.5mm, the focal length is-34.8 mm, the front surface curvature radius is-108.728, the rear surface curvature radius is 127.994, and the material is chalcogenide glass IRG206.
The central axis of the fifth objective lens 6 is respectively offset by 8mm in the horizontal and vertical directions along the optical axis of the system, and the central axes of the subsequent sixth objective lens 7, the seventh objective lens 8 and the detector 9 are coaxial with the central axis of the fifth objective lens 6 and keep the same offset.
The distance between the sixth objective lens 7 and the fifth objective lens 6 is 1.7mm, the clear aperture is 18.8mm, the focal length is 24.58mm, the curvature radius of the front surface is 69.6469, the curvature radius of the rear surface is 1327.27, and the material of the sixth objective lens is single crystal germanium.
The distance between the seventh objective lens 8 and the sixth objective lens 7 is 14mm, the clear aperture is 18.6mm, the focal length is-37.6 mm, the curvature radius of the front surface is-135.568, the curvature radius of the rear surface is 269.599, and the material of the seventh objective lens is monocrystalline silicon.
The distance between the detector 9 and the seventh objective lens 8 is 4mm, and the detector can be a refrigeration type infrared detector or a non-refrigeration type infrared detector. The size ratio of the length H to the width V of the image surface of the detector 9 is 6:4 or 16, and the material of the image surface is mercury cadmium telluride or indium antimonide. The working mode of the detector 9 is scanning staring, the working frame frequency of the detector is consistent with the scanning frame frequency of the Pechan prism, and the detection integration time is the same as the staying time of the Pechan prism at the scanning position.
The detector 9 is 16mm by 16mm in size.
Fig. 2 is a transfer function MTF graph of an infrared scanning optical system with an ultra-large field of view. As shown in FIG. 2, the MTF for each field is greater than 0.4 at 20 cycles/mm. This ensures that the lens objective can obtain high resolution image information.
Fig. 3 is a dot-column diagram of the infrared search and tracking system of the present invention. As can be seen from fig. 3, the RMS diameter of each field does not exceed 20 μm at the maximum.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made in the above embodiments by those of ordinary skill in the art without departing from the principle and spirit of the present invention.
Claims (10)
1. An infrared scanning optical system with an ultra-large field of view is characterized in that: the device comprises a first objective lens, a second objective lens, a third objective lens, a fourth objective lens, a Pechan prism, a fifth objective lens, a sixth objective lens, a seventh objective lens and a detector; the first objective lens, the second objective lens, the third objective lens, the fourth objective lens and the Pechan prism are sequentially and coaxially arranged along a first optical axis direction, and the first optical axis and a system optical axis are arranged; the fifth objective lens, the sixth objective lens, the seventh objective lens and the detector are sequentially and coaxially arranged behind the Pechan prism along a second optical axis direction;
the second optical axis direction and the first optical axis direction are offset in the two directions of x and y which are perpendicular to each other, and the offset is the half-image height size of the detector, namely the offset in the x direction: x = H detector /2,y Direction offset: y = V detector /2 wherein H detector Representing detector image plane length, V detector Representing the detector image plane width.
2. The ultra-large field of view infrared scanning optical system of claim 1, characterized in that: the central axis of the first objective lens is coaxial with the first optical axis, the focal length of the first objective lens is 48.4mm, the clear aperture is 18mm, the curvature radius of the front surface is-37.32, the curvature radius of the rear surface is-31.968, and the first objective lens is made of monocrystalline silicon;
the distance between the second objective lens and the first objective lens is 2.16mm, the focal length is-104.7 mm, the light transmission aperture is 25mm, the front surface curvature radius 61.848 and the rear surface curvature radius 37.21 are made of monocrystalline silicon;
the distance between the third objective lens and the second objective lens is 19.38mm, the focal length is 96.3mm, the light transmission aperture is 23mm, the curvature radius of the front surface is-44.869, the curvature radius of the rear surface is-49.45, and the third objective lens and the second objective lens are made of monocrystalline silicon;
the distance between the fourth objective lens and the third objective lens is 11.23mm, the focal length is 88.3mm, the clear aperture is 35.1mm, the curvature radius of the front surface is-90.765, the curvature radius of the rear surface is-76.423, and the material of the fourth objective lens is single crystal germanium;
the distance between the Pechan prism and the fourth objective is 10mm, and the aperture of the light passing through the Pechan prism is 45 multiplied by 45mm 2 The material is zinc sulfide or monocrystalline silicon.
3. The ultra-large field of view infrared scanning optical system of claim 2, characterized in that: the Pechan prism rotates 45 degrees, 90 degrees, 135 degrees and 180 degrees along the optical axis of the system in sequence; the rotational scanning of the Pechan prism realizes the imaging offset of an optical primary imaging surface, further realizes the spatial view field conversion of the Pechan prism in different scanning position systems, 4 frames of images obtained by 4 times of rotation are spliced to obtain a single frame of original images with 60 degrees, and the scanning circular view field can exceed 110 degrees after splicing.
4. The ultra-large field of view infrared scanning optical system of claim 2, characterized in that: and the central axis of the fifth objective lens is coaxial with the second optical axis and is offset by 8mm in the horizontal direction and the vertical direction respectively.
5. The ultra-large field of view infrared scanning optical system of claim 4, characterized in that: the center distance between the fifth objective lens and the Pechan prism is 10mm, the clear aperture is 22.5mm, the focal length is-34.8 mm, the curvature radius of the front surface is-108.728, the curvature radius of the rear surface is 127.994, and the fifth objective lens is made of chalcogenide glass IRG206;
the distance between the sixth objective lens and the fifth objective lens is 1.7mm, the clear aperture is 18.8mm, the focal length is 24.58mm, the curvature radius of the front surface is 69.6469, the curvature radius of the rear surface is 1327.27, and the material of the sixth objective lens is single crystal germanium;
the distance between the seventh objective lens and the sixth objective lens is 14mm, the clear aperture is 18.6mm, the focal length is-37.6 mm, the curvature radius of the front surface is-135.568, the curvature radius of the rear surface is 269.599, and the material of the seventh objective lens is monocrystalline silicon.
6. The ultra-large field of view infrared scanning optical system of claim 5, characterized in that: the distance between the detector and the seventh objective lens is 4mm, and the detector is a refrigeration type infrared detector or a non-refrigeration type infrared detector.
7. The ultra-large field of view infrared scanning optical system of claim 1, characterized in that: the size ratio of the length H to the width V of the image surface of the detector is 6:4 or 16, and the material of the image surface is mercury cadmium telluride or indium antimonide.
8. The ultra-large field of view infrared scanning optical system of claim 1, characterized in that: the working mode of the detector is scanning staring, the working frame frequency of the detector is consistent with the scanning frame frequency of the Pechan prism, and the detection integration time is the same as the staying time of the Pechan prism at the scanning position.
9. The ultra-large field of view infrared scanning optical system of claim 1, characterized in that: the detector size is 16mm x 16mm.
10. The ultra-large field of view infrared scanning optical system of any one of claims 1 to 9, characterized in that: the focal length F =38mm of the optical system, the scanning field angle is larger than or equal to 90 degrees multiplied by 90 degrees, the F number is 2, and the working waveband is 3-5 μm.
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