CN213240641U - Thermal imagery optical imaging device - Google Patents
Thermal imagery optical imaging device Download PDFInfo
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- CN213240641U CN213240641U CN202022188548.7U CN202022188548U CN213240641U CN 213240641 U CN213240641 U CN 213240641U CN 202022188548 U CN202022188548 U CN 202022188548U CN 213240641 U CN213240641 U CN 213240641U
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Abstract
The utility model discloses a thermal imagery optical imaging device, which comprises a sleeve with the end connected with an infrared detector, wherein the central line of the hollow sleeve is aligned with the center of the detector target surface of the infrared detector; a plurality of objective lens fixing tables are arranged in the sleeve, and the objective lens is fixed on the ring frame and is embedded on the objective lens fixing tables through the ring frame; the objective lens comprises a first objective lens, a second objective lens, a third objective lens and a fourth objective lens, wherein the first objective lens, the second objective lens and the third objective lens are sequentially arranged at the head of the sleeve, and the fourth objective lens is arranged at the tail of the sleeve; a space required by the rear intercept is reserved between the third objective and the fourth objective; the target surface of the detector is positioned at the imaging focal point of the fourth objective lens. The utility model provides a thermal imagery optical imaging device, which can meet the requirement of high precision infrared detection shooting of aircrafts including unmanned planes in flight; the image distortion at the edge of the field of view is less than or equal to 5 percent; the field angle is not less than 24 ° × 18 °; the unit pixel spatial resolution is no greater than 0.42m at heights exceeding 100 m.
Description
Technical Field
The utility model belongs to the technical field of the detector, a thermal imagery optical imaging device is related to.
Background
In recent years, the application of infrared technology and unmanned aerial vehicles is developed vigorously, and the importance of the infrared technology and the unmanned aerial vehicles is increasingly prominent in the national economy field and national defense military. The infrared image mainly reflects thermal radiation information of the target. Objects of different temperatures have distinct characteristics in the infrared band, with lower temperatures being darker in color. The infrared optical system detects the self radiation of the target, and compared with a visible light optical system, the infrared optical system has the advantages of all-weather observation, no environmental influence and strong penetrating power. For example, the environment monitoring is carried out by adopting the unmanned aerial vehicle infrared and visible light synchronous remote sensing technology, and the drainage blind hole hidden in the grass on both banks of the river can be effectively checked. Along with the improvement of application demand, the infrared detection technology in the flight of unmanned aerial vehicle has provided higher precision requirement.
Disclosure of Invention
The utility model provides a technical problem provide a thermal imagery optical imaging device, can be applicable to the high accuracy infrared detection in the flight.
The utility model discloses a realize through following technical scheme:
a thermal imagery optical imaging device comprises a sleeve, the tail end of the sleeve is connected with an infrared detector, and the center line of the hollow sleeve is aligned with the center of a detector target surface of the infrared detector; a plurality of objective lens fixing tables are arranged in the sleeve, and the objective lens is fixed on the ring frame and is embedded on the objective lens fixing tables through the ring frame;
the objective lens comprises a first objective lens, a second objective lens, a third objective lens and a fourth objective lens, wherein the first objective lens, the second objective lens and the third objective lens are sequentially arranged at the head of the sleeve, and the fourth objective lens is arranged at the tail of the sleeve; a space required by the rear intercept is reserved between the third objective and the fourth objective; the target surface of the detector is positioned at the imaging focal point of the fourth objective lens.
The ring frame is nested in the sleeve through threads, and matched threads are arranged on the objective lens fixing table and on the outer side of the sleeve.
The diameters of the ring frames for fixing the first objective lens, the second objective lens and the third objective lens are sequentially reduced, and the objective lens fixing tables for nesting the corresponding ring frames are sequentially arranged.
The first objective lens is used as a diaphragm for receiving light rays, and the first objective lens and the sleeve are sealed by using a sealant; the convex surface of the second objective lens is an aspheric surface so as to correct spherical aberration introduced by the first objective lens; the convex surface of the third objective lens is attached to the concave surface of the second objective lens so as to correct chromatic aberration; the convex surface of the fourth objective lens is an aspheric surface, and the back intercept distance between the third objective lens and the fourth objective lens can be adjusted by rotating the ring frame.
The total optical length of the objective lens formed by the first objective lens, the second objective lens, the third objective lens and the fourth objective lens is less than 50mm, the total thickness is 12mm, and the field of view is 24 degrees multiplied by 18 degrees.
Compared with the prior art, the utility model discloses following profitable technological effect has:
the utility model provides a thermal imagery optical imaging device, which can meet the requirement of high precision infrared detection shooting of aircrafts including unmanned planes in flight; the optical objective adopts a four-piece structure, and the aspheric surface design introduced into the optical surface of the objective can reduce the F number, improve the imaging quality of the edge of a view field, simultaneously reduce the high-grade spherical aberration of an off-axis view field and the high-grade spherical aberration of an on-axis aperture, and obtain higher imaging quality under the condition of a larger view field; by matching an optical system consisting of an objective lens with an infrared detector, the covering shooting of a 30m area below the optical system at the height of 100m can be achieved; image distortion at the edge of the field of view: less than or equal to 5 percent; a field angle of not less than 24 ° × 18 ° (lateral × longitudinal); the unit pixel spatial resolution is no greater than 0.42m at heights exceeding 100 m.
Drawings
FIG. 1 is a schematic view of a thermal imaging optical system according to the present invention;
fig. 2 is a schematic structural diagram of the present invention.
The target surface detection device comprises a first objective lens 1401, a second objective lens 1402, a third objective lens 1403, a fourth objective lens 1404, an infrared detector 1405, a sleeve 1406, a coil frame 1407 and a detector 1408.
Detailed Description
The present invention will now be described in further detail with reference to the attached drawings, which are provided for purposes of illustration and not limitation.
Referring to fig. 1 and 2, a thermal imagery optical imaging apparatus includes a sleeve 1406 with a distal end connected to an infrared detector 1405, the hollow sleeve 1406 having a centerline aligned with a center of a detector target surface 1408 of the infrared detector 1405; a plurality of objective lens fixing platforms are arranged in the sleeve 1406, and the objective lenses are fixed on the ring frame 1407 and are embedded on the objective lens fixing platforms through the ring frame 1407;
the objective lenses comprise a first objective lens 1401, a second objective lens 1402 and a third objective lens 1403 which are sequentially arranged at the head part of a sleeve 1406, and a fourth objective lens 1404 arranged at the tail part of the sleeve 1406; a space required by a rear intercept is left between the third objective 1403 and the fourth objective 1404; the detector target plane 1408 is located at the imaging focus of the fourth objective lens 1404.
The ring frame 1407 is embedded in the sleeve 1406 through threads, and the matching threads are arranged on the objective lens fixing table and on the outer side of the sleeve.
The diameters of the coils 1407 for fixing the first objective 1401, the second objective 1402 and the third objective 1403 are sequentially reduced, and the objective fixing tables for nesting the corresponding coils 1407 are sequentially arranged.
Specific examples are given below.
In order to satisfy the high accuracy infrared detection in the flight, the utility model provides a thermal imagery optical imaging device need cover the shooting at 100m height to below 30m region.
1) Optical system parameter requirements
Aiming at the imaging requirement, a thermal imager with 1028 multiplied by 768 resolution can meet the requirement of resolution; when the height exceeds 100m, the spatial resolution of the unit pixel is not more than 0.42 m; other optical system parameters require the following: frame frequency: not less than 5 fps; single frame exposure time: less than or equal to 40 ms; at the edge of the field of view, the image is distorted: less than or equal to 5 percent; a field angle of not less than 24 ° × 18 ° (lateral × longitudinal); the full-surface coverage can be realized by adopting a 24-degree and 18-degree view field, and when the confidence coefficient is 0.8, the reliability of the detection assembly is more than or equal to 0.99.
The optical system designed based on the above conditions requires: visual field: 24 ° × 18 °, caliber: Φ 34, integration time: 10ms, and the image distortion is less than or equal to 5% at the edge of a visual field.
The focal length is then calculated as:
the resolution of a receiving sensor (thermal imager) is 1024 × 768, the pixel size is 14 μm, the size of the target surface is 14.336mm × 10.752mm through calculation, the diagonal of the target surface is 17.92mm, the field size required by design is 24 ° × 18 °, and the focal length of the optical system is calculated by using the formula (1):
in the formula:
f' -optical system focal length in mm;
d is the height of the target surface in mm;
omega-half field angle, unit.
The focal length f' is 33.72mm calculated by the formula (1).
The entrance pupil diameter is calculated as:
the F number of the optical system is taken as 1, and the entrance pupil diameter of the system is calculated using equation (2):
in the formula:
d-entrance pupil diameter, in mm.
f' -the current field focal length in mm;
F#f number of System
Calculating the diameter of the entrance pupil by using the formula (2)
According to the above calculation, the external parameters required for the design of the optical system are as follows:
1) focal length: f ═ 33.72 mm;
2) wavelength range: 8-14 μm;
3) visual field: 2 ω 24 ° × 18 °;
4) f number: 1.
2) optical system design
In view of the large field of view of optical imaging, the optical objective adopts a four-piece structure to meet the imaging requirement. In order to reduce the F number and improve the imaging quality of the edge of a field of view, the optical surface of the objective adopts an aspheric surface, the structure can simultaneously reduce the high spherical aberration of an off-axis field of view and the high spherical aberration of an on-axis aperture, and can obtain higher imaging quality under the condition of a larger field of view.
The design result of the optical system is shown in figure 1, the optical effective aperture of the system is 32mm, and the optical total length is less than 50 mm. The first objective lens is made of germanium materials and serves as a diaphragm of the system and is used for receiving light rays in a large range; the second objective lens is used for correcting spherical aberration introduced by the first objective lens, and the germanium material is also adopted, and the convex surface of the second objective lens is an aspheric surface. And the third objective lens is made of zinc sulfide material and is used for correcting chromatic aberration of the system. The fourth objective lens is made of germanium materials, and the convex surface of the fourth objective lens is an aspheric surface, so that the rear intercept of the system is adjusted, and the final imaging quality is guaranteed. Image quality evaluation and detection show that MTF of the system is greater than 0.3(35lp/mm), the maximum field point array spot is 15 mu m and is approximately equal to one pixel size; the maximum distortion is less than 5%.
3) Transmittance calculation
The system transmittance was calculated according to equation (3)
τ＝τ1 N1×τ2 n (3)
In the formula:
tau-total transmittance
τ1-permeability of the interface with air, 99%;
n1 — number of transmission planes, 4;
τ2-optical material transmission, calculated from the absorption coefficient, 90%;
n-total thickness of material, 12 mm;
4) tolerance analysis
The imaging quality of the system can be influenced by the material error, the surface type error, the thickness error and the interval error of the optical lens, the errors are calculated by using a reversal sensitivity method, the surface type and the interval of the optical part are subjected to tolerance analysis, and an analysis result shows that the system is insensitive to the aperture and the material, and the processing and adjusting process is simple and feasible.
5) Optical-mechanical structure arrangement
Referring to fig. 2, an infrared detector 1405 is disposed at the end of sleeve 1406, and the centerline of sleeve 1406 is aligned with the center of detector target surface 1408 of infrared detector 1405; the objective lens is fixed on a coil 1407 and is nested in a sleeve 1406 by the coil 1407; first, second and third objectives 1401, 1402, and 1403 are disposed at the head of sleeve 1406, and fourth objective 1404 is disposed at the tail of sleeve 1406; a space is left between the third objective lens 1403 and the fourth objective lens 1404 to adjust a pitch required for the back intercept.
The utility model provides a thermal imagery optical imaging device can satisfy and be applied to the high accuracy infrared detection of aircraft including unmanned aerial vehicle in the flight and shoot.
The embodiments given above are preferred examples for implementing the present invention, and the present invention is not limited to the above-described embodiments. Any non-essential addition and replacement made by the technical features of the technical solution of the present invention by those skilled in the art all belong to the protection scope of the present invention.
Claims (5)
1. A thermographic optical imaging apparatus, comprising a sleeve (1406) having a distal end connected to an infrared detector (1405), the hollow sleeve (1406) having a centerline aligned with a center of a detector target surface (1408) of the infrared detector (1405); a plurality of objective lens fixing platforms are arranged in the sleeve (1406), and the objective lens is fixed on the ring frame (1407) and is embedded on the objective lens fixing platforms through the ring frame (1407);
the objective lens comprises a first objective lens (1401), a second objective lens (1402) and a third objective lens (1403) which are sequentially arranged at the head part of a sleeve (1406), and a fourth objective lens (1404) arranged at the tail part of the sleeve (1406); a distance required by a rear intercept is reserved between the third objective lens (1403) and the fourth objective lens (1404); the detector target surface (1408) is located at the imaging focus of the fourth objective lens (1404).
2. A thermographic optical imaging apparatus according to claim 1, in which the coil holder (1407) is threadedly nested in the sleeve (1406) and the objective lens holder is provided with mating threads on the outside of the sleeve.
3. A thermographic optical imaging apparatus according to claim 1, wherein the diameters of the rims (1407) holding the first objective (1401), the second objective (1402) and the third objective (1403) decrease in sequence, and objective holding stages for nesting the respective rims (1407) are arranged in sequence.
4. A thermographic optical imaging apparatus according to claim 1, wherein said first objective (1401) is a diaphragm for receiving light, and is sealed with a sealing compound with respect to said sleeve (1406); the convex surface of the second objective lens (1402) is an aspheric surface so as to correct spherical aberration introduced by the first objective lens (1401); the convex surface of the third objective lens (1403) is attached to the concave surface of the second objective lens (1402) so as to correct chromatic aberration; the convex surface of the fourth objective lens (1404) is an aspheric surface, and the back intercept distance between the third objective lens (1403) and the fourth objective lens (1404) can be adjusted by rotating the ring frame (1407).
5. A thermographic optical imaging apparatus according to claim 1, wherein said first objective (1401), second objective (1402), third objective (1403) and fourth objective (1404) constitute an objective having an optical total length of less than 50mm, a total thickness of 12mm and a field of view of 24 ° x 18 °.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202022188548.7U CN213240641U (en) | 2020-09-29 | 2020-09-29 | Thermal imagery optical imaging device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202022188548.7U CN213240641U (en) | 2020-09-29 | 2020-09-29 | Thermal imagery optical imaging device |
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| Publication Number | Publication Date |
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| CN213240641U true CN213240641U (en) | 2021-05-18 |
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| CN202022188548.7U Active CN213240641U (en) | 2020-09-29 | 2020-09-29 | Thermal imagery optical imaging device |
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| CN (1) | CN213240641U (en) |
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