Energy type wide-angle long-wave infrared lens

Abstract

The invention discloses an energy-type wide-angle long-wave infrared lens, the working wave band of the lens is 8-10.6 mu m, and the lens comprises a first infrared lens (1), a second infrared lens (2), a third infrared lens (3), a fourth infrared lens (4), a fifth infrared lens (5) and an optical filter (6) which are coaxially arranged from front to back along the direction of an optical path. The light spot size and light spot shape requirements required by an energy type wide-angle long-wave infrared system are considered, and the aperture weight and the view field weight are reasonably respectively combined, so that the lens realizes light spot phi 1.4 mm and uniform light spot energy distribution in a full view field 134-degree range, and the requirement of the energy type wide-angle long-wave lens for target detection is realized. The lens adopts a transmission-type light path structure and adopts a passive athermalization design, so that the lens can work normally within the temperature range of-40 DEG C to + 70 DEG C.

Description

Technical Field

[0001] The invention belongs to the technical field of optical system design, and relates to an optical lens, in particular to an energy-type wide-angle long-wave infrared lens. Background Art

[0002] The infrared lens is used in conjunction with the infrared detector, and the infrared signal emitted by the detected target is transmitted to the detector. The calculation program reads the size and shape of the light spot, uses an algorithm, and outputs the target position coordinates to achieve the detection function. Different from the traditional long-wave infrared imaging lens, the lens in this application mode does not focus on the imaging quality, but only on the size and shape of the light spot. At the same time, the special application environment of the satellite system requires the satellite optical lens to have radiation resistance.

[0003] As the core part of the system, the performance of the optical lens usually affects the lens's ability to search and track targets, and more importantly, directly affects its accuracy in detecting the target's position. From the perspective of the ability to detect targets, the larger the instantaneous field of view of the optical lens, the better. The target forms a spot of the same size and similar shape through the optical lens at a specified angle. In order to improve the anti-interference ability of the optical lens, extinction measures need to be added to the lens to reduce or eliminate the impact of background light and stray light on the accuracy of target position detection.

[0004] The present invention requires designing an energy-type wide-angle long-wave infrared lens to significantly reduce the volume of the optical system and realize the functions of long-wave infrared large-field detection and tracking in a compact space. Summary of the invention

[0005] (I) Purpose of the invention

[0006] The purpose of the present invention is to provide an energy-type wide-angle long-wave infrared lens to improve the adaptability of the application environment and the field of view of the infrared system and meet the needs of miniaturization; the long-wave infrared lens has a wavelength range of 8μm to 10.6μm and an operating temperature of -40℃ to +70℃. The optical lens realizes a passive athermal design within the operating temperature range, so that it can work normally within the temperature range of -40℃ to +70℃.

[0007] (II) Technical solution

[0008] In order to solve the above technical problems, the present invention provides an energy-type wide-angle long-wave infrared lens, comprising a first infrared lens 1, a second infrared lens 2, a third infrared lens 3, a fourth infrared lens 4, a fifth infrared lens 5, and a filter 6 coaxially arranged from front to back along the optical path direction, and an infrared detector is arranged behind the filter 6; the center of the optical surface is positive on the right side of the optical surface vertex, and the center of the optical surface is negative on the left side of the optical surface vertex; the long-wave infrared lens is used to correct the incident long-wave infrared and transmit the long-wave infrared to the infrared detector.

[0009] According to the direction of the light path, the left surface of all optical elements in the figure is defined as the front surface, and the right surface is defined as the back surface.

[0010] The aspheric formula of the lens involved in this scheme is:

[0011]

[0012] Among them, z is the sagittal height of the aspheric surface, c is the curvature at the vertex of the aspheric surface, R is the radius of curvature at the vertex of the aspheric surface, k is the cone coefficient, and r is the radial distance A, B, C, D, E, F, G, H, and J are the fourth-order, sixth-order, eighth-order, tenth-order, twelfth-order, fourteenth-order, sixteenth-order, eighteenth-order, and twentieth-order aspheric coefficients of the aspheric surface, respectively.

[0013] Note: The aspheric coefficients without specific values ​​in the text are all 0.

[0014] The material of the first infrared lens 1 is germanium, the front surface is aspherical, the radius of the front surface is in the range of 55 mm to 65 mm, k is 0, A is 0.00009 to 0.00011, B is -6.0e-7 to -3.0e-7, C is 0.5e-9 to 4.5e-9, D is -4.0e-12 to -0.5e-12, the radius of the rear surface is in the range of 9 mm to 25 mm, the front surface aperture is in the range of Φ25 mm to Φ35 mm, the rear surface aperture is in the range of Φ20 mm to Φ30 mm, and the optical thickness is in the range of 3 mm to 5 mm.

[0015] The optical material of the second infrared lens 2 is arsenic selenium germanium, the front surface is aspherical, the front surface radius ranges from 30mm to 60mm, k is 0, A is -0.0005 to -0.0002, B is 2.0e-6 to 5.0e-6, C is -3.2e-8 to -1.0e-8, the rear surface radius ranges from 85mm to 100mm, the front surface light aperture ranges from Φ13mm to Φ18mm, the rear surface light aperture ranges from Φ10mm to Φ17mm, and the optical thickness ranges from 3mm to 6mm;

[0016] The material of the third infrared lens 3 is arsenic selenium germanium, the front surface radius range is 90mm-140mm, the rear surface radius range is 80mm-110mm, the front surface light aperture range is Φ8mm-Φ12mm, the rear surface light aperture range is Φ8mm-Φ12mm, and the optical thickness range is 2.5mm-4.5mm;

[0017] The fourth infrared lens 4 is made of germanium, with a front surface radius ranging from 10 mm to 20 mm, a rear surface radius ranging from 10 mm to 20 mm, a front surface light aperture ranging from Φ5 mm to Φ10 mm, a rear surface light aperture ranging from Φ8 mm to Φ13 mm, and an optical thickness ranging from 4 mm to 7 mm;

[0018] The material of the fifth infrared lens 5 is arsenic selenium germanium, the front surface radius range is 18mm-38mm, the rear surface radius range is 150mm-300mm, the front surface light aperture range is Φ13mm-Φ18mm, the rear surface light aperture range is Φ13mm-Φ18mm, and the optical thickness range is 3mm-5mm;

[0019] The optical material of the filter is zinc selenide, the front and rear surfaces are both flat, the aperture is φ13mm~φ18mm and φ13mm~φ18mm respectively, and the optical thickness ranges from 1 to 4mm;

[0020] The distance between the first infrared lens 1 and the second infrared lens 2 varies in the range of 6 mm to 12 mm;

[0021] The distance between the second infrared lens 2 and the third infrared lens 3 varies in the range of 0.5 mm to 4.5 mm;

[0022] The distance between the third infrared lens 3 and the fourth infrared lens 4 varies in the range of 3.5 mm to 7.5 mm;

[0023] The distance between the fourth infrared lens 4 and the fifth infrared lens 5 varies in the range of 2 mm to 6 mm;

[0024] The distance between the fifth infrared lens 5 and the filter varies in the range of 0.1 mm to 12 mm.

[0025] (III) Beneficial effects

[0026] The energy-type wide-angle long-wave infrared lens provided by the above technical solution takes into account the spot size and spot shape requirements of the energy-type wide-angle long-wave infrared system, combines the requirements for the lens volume, and reasonably distinguishes the aperture weight and field of view weight, so that the lens can achieve a spot of Φ1.4mm within the full field of view of 134°, and the spot energy is evenly distributed, thereby meeting the target detection requirements of the energy-type wide-angle long-wave lens; the lens adopts a transmissive optical path structure and a passive athermal design, so that it can work normally in the temperature range of -40℃ to +70℃. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the structure of an energy-type wide-angle long-wave infrared lens;

[0028] Figure 2This is a light spot diagram of an energy-type wide-angle long-wave infrared lens at +20°;

[0029] Figure 3 This is a light spot diagram of an energy-type wide-angle long-wave infrared lens at -40°;

[0030] Figure 4 This is a light spot diagram of an energy-type wide-angle long-wave infrared lens at +70°;

[0031] Figure 5 This is a spot energy distribution diagram of an energy-type wide-angle long-wave infrared lens at different field of view points. DETAILED DESCRIPTION

[0032] In order to make the purpose, content and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below in conjunction with the drawings and examples.

[0033] The technical performance indicators of the energy-type wide-angle long-wave infrared lens of this embodiment are:

[0034] a) Long-wave infrared lens working band / wavelength: 8μm~10.6μm;

[0035] b) Detector specifications: 640*512@17μm

[0036] c) Total efficiency of long-wave infrared optical lens: not less than 80%;

[0037] d) Long-wave infrared optical lens field of view: 2ω=±67°;

[0038] e) Operating temperature range: -40℃~+70℃;

[0039] f) The spot diameter and shape within the ±45° field of view are similar: 0.85mm~1.7mm.

[0040] Reference Figure 1 As shown, the energy-type wide-angle long-wave infrared lens of this embodiment includes a first infrared lens 1, a second infrared lens 2, a third infrared lens 3, a fourth infrared lens 4, a fifth infrared lens 5, and a filter 6 coaxially arranged from front to back along the optical path direction, and an infrared detector is arranged behind the filter 6; the center of the optical surface is positive on the right side of the optical surface vertex, and the center of the optical surface is negative on the left side of the optical surface vertex; the long-wave infrared lens is used to correct the incident long-wave infrared and transmit the long-wave infrared to the infrared detector.

[0041] According to the direction of the light path, the left surface of all optical elements in the figure is defined as the front surface, and the right surface is defined as the back surface.

[0042] The aspheric formula of the lens involved in this embodiment is:

[0043]

[0044] Among them, z is the sagittal height of the aspheric surface, c is the curvature at the vertex of the aspheric surface, R is the radius of curvature at the vertex of the aspheric surface, k is the cone coefficient, and r is the radial distance A, B, C, D, E, F, G, H, and J are the fourth-order, sixth-order, eighth-order, tenth-order, twelfth-order, fourteenth-order, sixteenth-order, eighteenth-order, and twentieth-order aspheric coefficients of the aspheric surface, respectively.

[0045] Note: The aspheric coefficients without specific values ​​in the text are all 0

[0046] In this embodiment, the material of the first infrared lens 1 is germanium, the front surface is aspherical, the radius of the front surface ranges from 55 mm to 65 mm, k is 0, A is 0.00009 to 0.00011, B is -6.0e-7 to -3.0e-7, C is 0.5e-9 to 4.5e-9, D is -4.0e-12 to -0.5e-12, the radius of the rear surface ranges from 9 mm to 25 mm, the front surface aperture ranges from Φ25 mm to Φ35 mm, the rear surface aperture ranges from Φ20 mm to Φ30 mm, and the optical thickness ranges from 3 mm to 5 mm;

[0047] The optical material of the second infrared lens 2 is arsenic selenium germanium, the front surface is aspherical, the front surface radius ranges from 30mm to 60mm, k is 0, A is -0.0005 to -0.0002, B is 2.0e-6 to 5.0e-6, C is -3.2e-8 to -1.0e-8, the rear surface radius ranges from 85mm to 100mm, the front surface light aperture ranges from Φ13mm to Φ18mm, the rear surface light aperture ranges from Φ10mm to Φ17mm, and the optical thickness ranges from 3mm to 6mm;

[0048] The material of the third infrared lens 3 is arsenic selenium germanium, the front surface radius range is 90mm-140mm, the rear surface radius range is 80mm-110mm, the front surface light aperture range is Φ8mm-Φ12mm, the rear surface light aperture range is Φ8mm-Φ12mm, and the optical thickness range is 2.5mm-4.5mm;

[0049] The fourth infrared lens 4 is made of germanium, with a front surface radius ranging from 10 mm to 20 mm, a rear surface radius ranging from 10 mm to 20 mm, a front surface light aperture ranging from Φ5 mm to Φ10 mm, a rear surface light aperture ranging from Φ8 mm to Φ13 mm, and an optical thickness ranging from 4 mm to 7 mm;

[0050] The material of the fifth infrared lens 5 is arsenic selenium germanium, the front surface radius range is 18mm-38mm, the rear surface radius range is 150mm-300mm, the front surface light aperture range is Φ13mm-Φ18mm, the rear surface light aperture range is Φ13mm-Φ18mm, and the optical thickness range is 3mm-5mm;

[0051] The optical material of the filter is zinc selenide, the front and rear surfaces are both flat, the aperture is φ13mm~φ18mm and φ13mm~φ18mm respectively, and the optical thickness ranges from 1 to 4mm;

[0052] The distance between the first infrared lens 1 and the second infrared lens 2 varies in the range of 6 mm to 12 mm;

[0053] The distance between the second infrared lens 2 and the third infrared lens 3 varies in the range of 0.5 mm to 4.5 mm;

[0054] The distance between the third infrared lens 3 and the fourth infrared lens 4 varies in the range of 3.5 mm to 7.5 mm;

[0055] The distance between the fourth infrared lens 4 and the fifth infrared lens 5 varies in the range of 2 mm to 6 mm;

[0056] The distance between the fifth infrared lens 5 and the filter varies in the range of 0.1 mm to 12 mm.

[0057] Figure 2 to Figure 4 These are the light spot diagrams of the energy-type wide-angle long-wave infrared lens at +20℃, -40℃, and +70℃. Figure 5 This is a spot energy distribution diagram of an energy-type wide-angle long-wave infrared lens at different field of view points; the lens half field of view is 0°, 20.1°, 33.5°, 47° and 67°. Since the positive field of view and the negative direction spot distribution are the same, only the positive field of view is taken.

[0058] from Figures 2 to 5 It can be seen that the spot size of 1.2mm to 1.6mm and the shape of the optical lens in each field of view of this best embodiment meet the requirements, and the energy distribution is uniform.

[0059] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An energy-type wide-angle long-wave infrared lens, characterized in that: include: A first infrared lens (1), a second infrared lens (2), a third infrared lens (3), a fourth infrared lens (4), a fifth infrared lens (5), and a filter (6) are coaxially arranged from front to back along the optical path, and an infrared detector is arranged behind the filter (6); the center of the optical surface is positive when it is on the right side of the optical surface vertex, and negative when it is on the left side of the optical surface vertex; and the long-wave infrared lens is used to correct the incident long-wave infrared and transmit the long-wave infrared to the infrared detector.

2. The energy-type wide-angle long-wave infrared lens according to claim 1, characterized in that: According to the direction of the optical path, the left surface of all optical elements is defined as the front surface, and the right surface is defined as the back surface. The aspheric surface formula satisfied by the aspheric surface of each lens is: Among them, z is the sagittal height of the aspheric surface, c is the curvature at the vertex of the aspheric surface, R is the radius of curvature at the vertex of the aspheric surface, k is the cone coefficient, and r is the radial distance A, B, C, D, E, F, G, H, and J are the fourth-order, sixth-order, eighth-order, tenth-order, twelfth-order, fourteenth-order, sixteenth-order, eighteenth-order, and twentieth-order aspheric coefficients of the aspheric surface, respectively.

3. The energy-type wide-angle long-wave infrared lens as claimed in claim 2, characterized in that: The material of the first infrared lens (1) is germanium, the front surface is an aspherical surface, the radius of the front surface ranges from 55 mm to 65 mm, k is 0, A is 0.00009 to 0.00011, B is -6.0e-7 to -3.0e-7, C is 0.5e-9 to 4.5e-9, D is -4.0e-12 to -0.5e-12, the radius of the rear surface ranges from 9 mm to 25 mm, the front surface light aperture ranges from Φ25 mm to Φ35 mm, the rear surface light aperture ranges from Φ20 mm to Φ30 mm, and the optical thickness ranges from 3 mm to 5 mm.

4. The energy-type wide-angle long-wave infrared lens as claimed in claim 3, characterized in that: The optical material of the second infrared lens (2) is arsenic selenium germanium, the front surface is an aspherical surface, the radius of the front surface ranges from 30 mm to 60 mm, k is 0, A is -0.0005 to -0.0002, B is 2.0e-6 to 5.0e-6, C is -3.2e-8 to -1.0e-8, the radius of the rear surface ranges from 85 mm to 100 mm, the front surface light aperture ranges from Φ13 mm to Φ18 mm, the rear surface light aperture ranges from Φ10 mm to Φ17 mm, and the optical thickness ranges from 3 mm to 6 mm.

5. The energy-type wide-angle long-wave infrared lens as claimed in claim 4, characterized in that: The material of the third infrared lens (3) is arsenic selenium germanium, the front surface radius ranges from 90 mm to 140 mm, the rear surface radius ranges from 80 mm to 110 mm, the front surface light aperture ranges from Φ8 mm to Φ12 mm, the rear surface light aperture ranges from Φ8 mm to Φ12 mm, and the optical thickness ranges from 2.5 mm to 4.5 mm.

6. The energy-type wide-angle long-wave infrared lens as claimed in claim 5, characterized in that: The fourth infrared lens (4) is made of germanium, has a front surface radius ranging from 10 mm to 20 mm, a rear surface radius ranging from 10 mm to 20 mm, a front surface light aperture ranging from Φ5 mm to Φ10 mm, a rear surface light aperture ranging from Φ8 mm to Φ13 mm, and an optical thickness ranging from 4 mm to 7 mm.

7. The energy-type wide-angle long-wave infrared lens as claimed in claim 6, characterized in that: The material of the fifth infrared lens (5) is arsenic selenium germanium, the front surface radius ranges from 18mm to 38mm, the rear surface radius ranges from 150mm to 300mm, the front surface light aperture ranges from Φ13mm to Φ18mm, the rear surface light aperture ranges from Φ13mm to Φ18mm, and the optical thickness ranges from 3mm to 5mm.

8. The energy-type wide-angle long-wave infrared lens as claimed in claim 7, characterized in that: The optical material of the filter is zinc selenide, the front and rear surfaces are both flat, the light apertures are φ13mm~φ18mm and φ13mm~φ18mm respectively, and the optical thickness ranges from 1 to 4mm.

9. The energy-type wide-angle long-wave infrared lens as claimed in claim 8, characterized in that: The distance between the first infrared lens (1) and the second infrared lens (2) varies in the range of 6 mm to 12 mm; the distance between the second infrared lens (2) and the third infrared lens (3) varies in the range of 0.5 mm to 4.5 mm; the distance between the third infrared lens (3) and the fourth infrared lens (4) varies in the range of 3.5 mm to 7.5 mm; the distance between the fourth infrared lens (4) and the fifth infrared lens (5) varies in the range of 2 mm to 6 mm; and the distance between the fifth infrared lens (5) and the filter varies in the range of 0.1 mm to 12 mm.

10. An infrared imaging system, characterized in that: The invention comprises the energy-type wide-angle long-wave infrared lens according to any one of claims 1 to 9.

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