An ultra-wide field of view infrared scanning optical system

Abstract

This invention discloses an ultra-large field-of-view infrared scanning optical system, belonging to the field of detection and reconnaissance technology. It includes a first objective lens, a second objective lens, a third objective lens, a fourth objective lens, a Behan prism, a fifth objective lens, a sixth objective lens, a seventh objective lens, and a detector. The first objective lens, second objective lens, third objective lens, fourth objective lens, and Behan prism are arranged coaxially along a first optical axis, which is the system optical axis. The fifth objective lens, sixth objective lens, seventh objective lens, and detector are arranged coaxially behind the Behan prism along a second optical axis. The second optical axis is offset from the first optical axis in two perpendicular directions, x and y, with the offset amount equal to the half-image height of the detector, i.e., the x-direction offset: x = H. detector / 2, y-direction offset: y = V detector / 2, where H detector V represents the length of the detector image plane. detector This indicates the width of the detector's image plane. This invention employs a step-gaze scanning method using a Behring prism, and obtains higher resolution, larger image frames through multi-frame video stitching.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of detection and investigation, and particularly relates to a super-large field-of-view infrared scanning optical system. BACKGROUND

[0002] The infrared detection and warning system is a high-efficiency modern reconnaissance means, and has been widely popularized in the military and civilian fields. Especially under the condition of severe natural environment and interference of other systems, the infrared detection and warning system still has very strong detection and positioning capabilities. In the field of detection and investigation, the infrared detection and warning system can be used as situation awareness and passive warning, and mainly provides detection and positioning of scene targets and threat awareness capability. The infrared detection and warning system has imaging performance and can be used for day and night scene navigation or visual judgment.

[0003] In order to improve the detection and warning capability, the infrared detection and warning system needs to obtain a wider detection field of view and a higher resolution image. At present, the main method for improving the detection capability is to design a larger scale and higher resolution infrared integral detector and optical matching to obtain a higher definition detection image. However, the high-resolution infrared detector is very expensive, which greatly increases the development cost of the system. Moreover, the use of a larger area infrared detector will greatly increase the volume and weight of the optical system, which brings difficulties to the application of the airborne warning platform with high space size requirement. SUMMARY

[0004] Technical problems to be solved:

[0005] In order to avoid the shortcomings of the prior art, the present application provides a super-large field-of-view infrared scanning optical system, which is a compact large field-of-view warning optical system. The technical scheme improves the warning resolution and detection performance under the condition of limited cost of the detector. The present application adopts a large field-of-view partially offset optical path design, adopts a step-by-step gazing scanning of the Berek prism, and obtains a higher resolution and larger image frame through multi-frame video splicing. The purpose of reducing the development cost and improving the system detection performance is achieved.

[0006] The technical scheme of the present application is as follows: a super-large field-of-view infrared scanning optical system, comprising a first objective lens, a second objective lens, a third objective lens, a fourth objective lens, a Berek 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 Berek prism are coaxially arranged in sequence along a first optical axis direction, which is a first optical axis and a system optical axis; the fifth objective lens, the sixth objective lens, the seventh objective lens and the detector are coaxially arranged in sequence after the Berek prism along a second optical axis direction.

[0007] The second optical axis direction is offset from the first optical axis direction in the perpendicular x and y directions, and the offset amount is half of the image height of the detector, that is, the x-direction offset amount x = H / 2 and the y-direction offset amount y = V. detector ​detector / 2, wherein H detector represents the length of the detector image plane, V detector represents the width of the detector image plane.

[0008] A further technical solution of the present application is that the central axis of the first objective is coaxial with the first optical axis, the focal length is 48.4 mm, the clear aperture is 18 mm, the front surface curvature radius is -37.32, the rear surface curvature radius is -31.968, and the material is single crystal silicon;

[0009] The second objective is spaced apart from the first objective by 2.16 mm, the focal length is -104.7 mm, the clear aperture is 25 mm, the front surface curvature radius is 61.848, the rear surface curvature radius is 37.21, and the material is single crystal silicon;

[0010] The third objective is spaced apart from the second objective by 19.38 mm, the focal length is 96.3 mm, the clear aperture is 23 mm, the front surface curvature radius is -44.869, the rear surface curvature radius is -49.45, and the material is single crystal silicon;

[0011] The fourth objective is spaced apart from the third objective by 11.23 mm, the focal length is 88.3 mm, the clear aperture is 35.1 mm, the front surface curvature radius is -90.765, the rear surface curvature radius is -76.423, and the material is single crystal germanium;

[0012] The Abbe prism is spaced apart from the fourth objective by 10 mm, and the clear aperture is 45*45 mm 2 , and the material is zinc sulfide or single crystal silicon.

[0013] A further technical solution of the present application is that the Abbe prism is rotated by 45°, 90°, 135° and 180° along the system optical axis in sequence; the rotation scanning of the Abbe prism realizes the imaging offset of the optical primary imaging plane, and further realizes the space field of view transformation of the system at different scanning positions of the Abbe prism, four images obtained through four rotations are spliced to obtain a single frame of 60° original image, and the scanning circular field of view can be more than 110° after splicing.

[0014] A further technical solution of the present application is that the central axis of the fifth objective is coaxial with the second optical axis, and is offset by 8 mm in the horizontal and vertical directions respectively.

[0015] A further technical solution of the present application is that the fifth objective is spaced apart from the Abbe prism by 10 mm, the clear aperture is 22.5 mm, 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 sulfide glass IRG206;

[0016] The interval between the sixth objective and the fifth objective is 1.7 mm, the light aperture is 18.8 mm, the focal length is 24.58 mm, the front surface curvature radius is 69.6469, the rear surface curvature radius is 1327.27, and the material is monocrystalline germanium;

[0017] The interval between the seventh objective and the sixth objective is 14 mm, the light aperture is 18.6 mm, the focal length is -37.6 mm, the front surface curvature radius is -135.568, the rear surface curvature radius is 269.599, and the material is monocrystalline silicon.

[0018] A further technical solution of the present application is that the interval between the detector and the seventh objective is 4 mm, and the detector is a refrigeration type infrared detector or a non-refrigeration type infrared detector.

[0019] A further technical solution of the present application is that the length H and the width V of the detector image surface are in a size ratio of 6:4 or 16:9, and the image surface material is tellurium cadmium mercury or indium antimonide.

[0020] A further technical solution of the present application is that the working mode of the detector is scanning gaze, the working frame frequency is consistent with the scanning frame frequency of the Abbe prism, and the detection integration time is the same as the dwell time of the Abbe prism at the scanning position.

[0021] A further technical solution of the present application is that the size of the detector is 16 mm x 16 mm.

[0022] A further technical solution of the present application is that the focal length of the optical system is f=38 mm, the scanning field of view angle is greater than or equal to 90°x 90°, the F number is 2, and the working waveband is 3 μm-5 μm.

[0023] Beneficial effects

[0024] The present application has the beneficial effect that the super-large field of view infrared scanning optical system can be applied to police security, military infrared warning and investigation, etc. It has the advantages of large detection field of view, high resolution, and small scanning envelope occupying space. It can effectively improve the resolution of the detection system, increase the visible distance, expand the investigation range, and enhance the identification ability of the target.

[0025] 1. The present application only uses 7 lenses to achieve the design, the instantaneous field of view angle is greater than or equal to 60°, the scanning field of view angle is greater than or equal to 110°, and the total length of the system is less than or equal to 300 mm.

[0026] 2. The present application is applied to infrared super-wide-angle monitoring photoelectric products, and the full field of view optical resolution is improved by one time, and the scanning field of view is improved by one time.

[0027] 3. The prism offset scanning mode designed in the present application can compress the axial volume by more than one third, expand the application scenarios of the system, and meet the miniaturization demand of the product. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a diagram of the super large field of view infrared scanning optical system of the present application.

[0029] Figure 2 is a diagram of the transfer function MTF of the super large field of view infrared scanning optical system of the present application.

[0030] Figure 3 is a diagram of the spot diagram of the super large field of view infrared scanning optical system of the present application.

[0031] BRIEF DESCRIPTION OF DRAWINGS: 1. first objective, 2. second objective, 3. third objective, 4. fourth objective, 5. Rochon prism, 6. fifth objective, 7. sixth objective, 8. seventh objective, 9. detector. DETAILED DESCRIPTION

[0032] The embodiments described below are exemplary and are intended to explain the present application, and are not to be understood as limiting the present application.

[0033] In the description of the present application, 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 the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0034] As shown in Figure 1 , the specific parameters of the long focal large field of view infrared search and tracking optical system of the present embodiment are as follows:

[0035] (I) Optical system

[0036] Focal length f = 38 mm;

[0037] F number 2;

[0038] Scanning field of view ≥ 110°.

[0039] (II) Infrared detector

[0040] Pixel size: 15 μm x 15 μm

[0041] Effective pixels: 2048H x 2048V

[0042] (III) Working wavelength band: 3 μm ~ 5 μm

[0043] The super-large field of view 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 Berek prism 5, a fifth objective lens 6, a sixth objective lens 7, a seventh objective lens 8 and a detector 9. The first objective lens 1, the second objective lens 2, the third objective lens 3, the fourth objective lens 4 and the Berek prism 5 are coaxially arranged in sequence, the fifth objective lens 6, the sixth objective lens 7, the seventh objective lens 8 and the detector 9 are sequentially arranged along the optical axis direction after the Berek prism 5, and are offset from the optical axis in the x and y directions perpendicular to the optical axis, and the offset amount is half the image height of the detector 9, that is, the x-direction offset amount x = l detector / 2, and the y-direction offset amount y = h detector / 2.

[0044] The specific parameters of the optical system are as follows:

[0045] The central axis of the first objective lens 1 is coaxial with the system optical axis, the focal length is 48.4 mm, the clear aperture is 18 mm, the front surface curvature radius is -37.32, the rear surface curvature radius is -31.968, and the material is single crystal silicon.

[0046] The central axis of the second objective lens 2 is coaxial with the system optical axis, the distance from the first objective lens 1 is 2.16 mm, the focal length is -104.7 mm, the clear aperture is 25 mm, the front surface curvature radius is 61.848, the rear surface curvature radius is 37.21, and the material is single crystal silicon.

[0047] The central axis of the third objective lens 3 is coaxial with the system optical axis, the distance from the second objective lens 2 is 19.38 mm, the focal length is 96.3 mm, the clear aperture is 23 mm, the front surface curvature radius is -44.869, the rear surface curvature radius is -49.45, and the material is single crystal silicon.

[0048] The central axis of the fourth objective lens 4 is coaxial with the system optical axis, the distance from the third objective lens 3 is 11.23 mm, the focal length is 88.3 mm, the clear aperture is 35.1 mm, the front surface curvature radius is -90.765, the rear surface curvature radius is -76.423, and the material is single crystal germanium.

[0049] The central axis of the Berek prism 5 is coaxial with the system optical axis, the distance from the fourth lens 4 is 10 mm, and the clear aperture is 45x45 mm 2 , and the material is single crystal silicon.

[0050] The Berek prism 5 is rotated by 45°, 90°, 135° and 180° along the system optical axis in sequence; the rotation scanning of the Berek prism realizes the imaging offset of the optical primary imaging surface, and further realizes the space field of view transformation of the system at different scanning positions of the Berek prism; four images obtained by four rotations are spliced to obtain a single frame of 60° original image, and the scanning circular field of view after splicing can be more than 110°.

[0051] The center distance between the fifth objective lens 6 and the Behan prism 5 is 10mm, the light transmission diameter is 22.5mm, the focal length is -34.8mm, the front surface curvature radius is -108.728, the rear surface curvature radius is 127.994, and its material is chalcogenide glass IRG206.

[0052] The central axis of the fifth objective lens 6 is offset by 8 mm in both the horizontal and vertical directions along the optical axis of the system. The central axes of the subsequent sixth objective lens 7, seventh objective lens 8, and detector 9 are coaxial with the central axis of the fifth objective lens 6 and maintain the same offset.

[0053] The distance between the sixth objective lens 7 and the fifth objective lens 6 is 1.7 mm, the aperture is 18.8 mm, the focal length is 24.58 mm, the front surface curvature radius is 69.6469, the rear surface curvature radius is 1327.27, and the material is single crystal germanium.

[0054] The seventh objective lens 8 is 14mm apart from the sixth objective lens 7, has an aperture of 18.6mm, a focal length of -37.6mm, a front surface radius of curvature of -135.568, a rear surface radius of curvature of 269.599, and is made of single-crystal silicon.

[0055] The distance between the detector 9 and the seventh objective lens 8 is 4 mm, and it can be a cooled infrared detector or an uncooled infrared detector. The aspect ratio of the image plane length H to width V of the detector 9 is 6:4 or 16:9, and the image plane material is mercury cadmium telluride or indium antimonide. The detector 9 operates in a scanning staring mode, and its operating frame rate is consistent with the scanning frame rate of the Behan prism. The detection integration time is the same as the dwell time of the Behan prism at the scanning position.

[0056] The detector 9 measures 16mm × 16mm.

[0057] Figure 2 This is the MTF (Mean Transfer Function) plot of an ultra-large field-of-view infrared scanning optical system. (Example:) Figure 2 As shown, at 20 cycles / mm, the MTF of each field of view is greater than 0.4. This ensures that the lens objective can obtain high-resolution image information.

[0058] Figure 3 This is a dot matrix diagram of the infrared search and tracking system of the present invention. From... Figure 3 It can be seen that the maximum RMS diameter of each field of view does not exceed 20μm.

[0059] 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. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A super-large field-of-view infrared scanning optical system, characterized in that: Including the first objective lens, second objective lens, third objective lens, fourth objective lens, Behring prism, fifth objective lens, sixth objective lens, seventh objective lens, and detector; The first objective lens, the second objective lens, the third objective lens, the fourth objective lens, and the Behan prism are arranged coaxially in sequence along the first optical axis; the fifth objective lens, the sixth objective lens, the seventh objective lens, and the detector are arranged coaxially in sequence after the Behan prism along the second optical axis. The second optical axis is offset from the first optical axis in two perpendicular directions, x and y, and the offset amount is equal to the half-image height dimension of the detector, i.e., the offset amount in the x direction: y-direction offset: ,in, Indicates the length of the detector image plane. Indicates the width of the detector image plane; The central axis of the first objective lens is coaxial with the first optical axis, its focal length is 48.4 mm, its light transmission diameter is 18 mm, its front surface curvature radius is -37.32, its rear surface curvature radius is -31.968, and its material is single crystal silicon. The distance between the second objective lens and the first objective lens is 2.16 mm, the focal length is -104.7 mm, the aperture is 25 mm, the radius of curvature of the front surface is 61.848, the radius of curvature of the rear surface is 37.21, and the material is single crystal silicon. The distance between the third objective lens and the second objective lens is 19.38 mm, the focal length is 96.3 mm, the aperture is 23 mm, the front surface curvature radius is -44.869, the rear surface curvature radius is -49.45, and the material is single crystal silicon. The fourth objective lens is 11.23 mm apart from the third objective lens, has a focal length of 88.3 mm, a light-transmitting aperture of 35.1 mm, a front surface curvature radius of -90.765, a rear surface curvature radius of -76.423, and is made of single-crystal germanium. The distance between the Biehan prism and the fourth objective lens is 10mm, and the aperture is 45×45mm. 2 Its material is zinc sulfide or monocrystalline silicon; The center distance between the fifth objective lens and the Behan prism is 10mm, the light transmission diameter is 22.5mm, the focal length is -34.8mm, the front surface radius of curvature is -108.728, the rear surface radius of curvature is 127.994, and its material is chalcogenide glass IRG206. The distance between the sixth objective lens and the fifth objective lens is 1.7 mm, the aperture is 18.8 mm, the focal length is 24.58 mm, the radius of curvature of the front surface is 69.6469, the radius of curvature of the rear surface is 1327.27, and the material is single crystal germanium. The seventh objective lens is 14mm apart from the sixth objective lens, has an aperture of 18.6mm, a focal length of -37.6mm, a front surface radius of curvature of -135.568, a rear surface radius of curvature of 269.599, and is made of single-crystal silicon.

2. The ultra-large field-of-view infrared scanning optical system according to claim 1, characterized in that: The Behan prism rotates sequentially along the optical axis of the system by 45°, 90°, 135° and 180°; the rotational scanning of the Behan prism realizes the imaging bias of the optical primary imaging surface, thereby realizing the spatial field of view transformation of the Behan prism system at different scanning positions. The four frames of images obtained by the four rotations are stitched together with the original 60° images of each frame, and the stitched circular field of view can exceed 110°.

3. The ultra-large field-of-view infrared scanning optical system according to claim 1, characterized in that: The central axis of the fifth objective lens is coaxial with the second optical axis, and is offset by 8 mm in both the horizontal and vertical directions.

4. The ultra-large field-of-view infrared scanning optical system according to claim 1, characterized in that: The distance between the detector and the seventh objective lens is 4 mm, and it is either a cooled infrared detector or an uncooled infrared detector.

5. The ultra-large field-of-view infrared scanning optical system according to claim 1, characterized in that: The detector's image plane length H and width V have a ratio of 6:4 or 16:9, and the image plane material is mercury cadmium telluride or indium antimonide.

6. The ultra-large field-of-view infrared scanning optical system according to claim 1, characterized in that: The detector operates in a scanning gaze mode, with its operating frame rate matching the scanning frame rate of the Behan prism, and its detection integration time matching the dwell time of the Behan prism at the scanning position.

7. The ultra-large field-of-view infrared scanning optical system according to claim 1, characterized in that: The detector measures 16mm × 16mm.

8. The ultra-large field-of-view infrared scanning optical system according to any one of claims 1-7, characterized in that: The optical system has a focal length of f=38mm, a scanning field of view ≥90°×90°, an F number of 2, and a working wavelength of 3μm~5μm.

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