Object space telecentric infrared macro lens

Abstract

The invention discloses an object space telecentric infrared macro lens, and belongs to the technical field of optical lenses, the object space telecentric infrared macro lens comprises a first lens, a second lens, a third lens, a diaphragm, a fourth lens and a fifth lens which are sequentially arranged from an object side to an image side along an optical axis, the third lens can move along the optical axis for focusing, and the first lens is a biconvex lens with positive focal power; the second lens, the fourth lens and the fifth lens are meniscus lenses which have positive focal power and protrude towards the object side. The third lens is a meniscus lens which has negative focal power and is convex towards the object side; and the focal length ratio of each lens is reasonably set. According to the macro lens, the problems of low imaging quality, poor stability and the like of the existing infrared macro lens are solved, and consistent magnification and high resolution in a short-distance range can be realized.

Description

Technical Field

[0001] This invention belongs to the field of optical lens technology, specifically relating to an object-side telecentric infrared macro lens. Background Technology

[0002] In today's rapidly developing technological era, infrared imaging technology plays a crucial role in numerous fields. In industrial inspection, it can penetrate darkness and smoke to accurately identify minute defects in objects; in security monitoring, it enables effective all-weather monitoring in complex environments; and in the medical field, it provides thermal imaging information of the human and animal interiors. Meanwhile, macro lenses focus on high-resolution imaging of close-range objects, clearly revealing minute details. Combining infrared imaging with macro capabilities to develop high-performance infrared macro lenses has become key to meeting the needs of specific fields.

[0003] However, traditional infrared macro lenses currently face numerous challenges. Firstly, they do not fully consider the object-side telecentric design principle: a telecentric design effectively reduces magnification changes caused by variations in object distance, ensuring image accuracy and stability. However, current traditional infrared macro lenses are deficient in this regard, causing even small changes in object distance to lead to significant fluctuations in image quality during close-up shooting, making it difficult to achieve a clear and consistent image within a specific object distance range. Secondly, they are prone to optical aberrations such as chromatic aberration and spherical aberration, which greatly affect image quality. Furthermore, they suffer from poor stability; their performance easily degrades in complex working environments, failing to meet the requirements for long-term stable use. Summary of the Invention

[0004] The purpose of this invention is to address the above-mentioned problems by proposing an object-side telecentric infrared macro lens, which solves the problems of low imaging quality and poor stability of existing infrared macro lenses, and can achieve consistent magnification and high resolution within a close range of 120mm-140mm.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] The present invention proposes a telecentric infrared macro lens, comprising a first lens, a second lens, a third lens, an aperture stop, a fourth lens, and a fifth lens arranged sequentially along the optical axis from the object side to the image side, wherein the third lens is capable of focusing by moving along the optical axis.

[0007] The first lens is a biconvex lens with positive optical power;

[0008] The second, fourth, and fifth lenses are all meniscus lenses with positive optical power and convex to the object side;

[0009] The third lens is a meniscus lens with negative optical power and convex to the object side;

[0010] The object-centric telecentric infrared macro lens also meets the following conditions:

[0011] 0.75≤|f1 / f|≤0.85, 0.44≤|f2 / f|≤0.54, 0.2≤|f3 / f|≤0.3,

[0012] 0.3≤|f4 / f|≤0.4, 1.45≤|f5 / f|≤1.55;

[0013] Where f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, f5 is the focal length of the fifth lens, and f is the effective focal length of the object-side telecentric infrared macro lens, in mm.

[0014] Preferably, the object-side telecentric infrared macro lens also satisfies the following conditions:

[0015] 175.5≤R1≤193.4, -605.2≤R2≤-562.4,

[0016] 70.6≤R3≤83.4, 535.3≤R4≤564.5,

[0017] 52.2≤R5≤63.1, 19.5≤R6≤24.2,

[0018] 10≤R7≤70, 26.5≤R8≤31.5

[0019] 48.6≤R9≤55.0, 422.5≤R10≤465.4;

[0020] Wherein, R1, R3, R5, R7, and R9 are the object-side radii of curvature of the first lens, second lens, third lens, fourth lens, and fifth lens, respectively, and R2, R4, R6, R8, and R10 are the image-side radii of curvature of the first lens, second lens, third lens, fourth lens, and fifth lens, respectively, in mm.

[0021] Preferably, the object-side telecentric infrared macro lens also satisfies the following conditions:

[0022] 40≤A1≤45, 9.0≤A2≤12, 3.5≤A3≤6.6,

[0023] 13.5≤A4≤15.5, 6.5≤A5≤7.8;

[0024] Where A1 is the air gap between the first and second lenses, A2 is the air gap between the second and third lenses, A3 is the air gap between the third lens and the aperture stop, A4 is the air gap between the aperture stop and the fourth lens, and A5 is the air gap between the fourth and fifth lenses, all in mm.

[0025] Preferably, the object-side telecentric infrared macro lens also satisfies the following conditions:

[0026] 7.5≤d1≤8.5, 7.0≤d2≤7.8, 5.0≤d3≤6.0,

[0027] 5.0≤d4≤6.0, 4.0≤d5≤5.2;

[0028] Wherein, d1 is the center thickness of the first lens, d2 is the center thickness of the second lens, d3 is the center thickness of the third lens, d4 is the center thickness of the fourth lens, and d5 is the center thickness of the fifth lens, in mm.

[0029] Preferably, the object-side and image-side mirrors of the first, fourth, and fifth lenses are aspherical, the object-side mirrors of the second and third lenses are aspherical, the image-side mirror of the second lens is a diffraction surface, and the image-side mirror of the third lens is a spherical surface.

[0030] Preferably, the aspherical surface satisfies the following expression:

[0031] + + +

[0032] In the formula, radial distance on an aspherical surface The sag of the position, For curvature, = 1 / R, where R is the radius of curvature of the corresponding mirror surface. The conic coefficient, , , These are higher-order aspheric coefficients;

[0033] The phase distribution of the diffraction plane satisfies the following expression:

[0034]

[0035] In the formula, The radial distance of the diffraction surface Phase of position, For diffraction orders, To normalize the radius, , is the phase coefficient of the diffraction surface.

[0036] Preferably, the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are all chalcogenide glass lenses.

[0037] Preferably, the object-side telecentric infrared macro lens also satisfies the following conditions:

[0038] 2.4≤n1≤2.9, 2.5≤n2≤2.9, 2.2≤n3≤2.8,

[0039] 2.2≤n4≤2.8, 2.4≤n5≤2.9;

[0040] Where n1 is the refractive index of the first lens, n2 is the refractive index of the second lens, n3 is the refractive index of the third lens, n4 is the refractive index of the fourth lens, and n5 is the refractive index of the fifth lens.

[0041] Preferably, the working wavelength of the object-side telecentric infrared macro lens is 8μm-12μm, and the object distance is 120mm-140mm.

[0042] Preferably, the object-side telecentric infrared macro lens also satisfies the following conditions:

[0043] 1.17≤TTL / f≤1.31, 95≤f≤105, 1:1.1≤F#≤1:1.3;

[0044] Where TTL is the total optical length of the object-side telecentric infrared macro lens, in mm; F# is the relative aperture of the object-side telecentric infrared macro lens.

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0046] 1) High imaging quality and detection accuracy: The five-lens design achieves a telecentric object-side design, ensuring consistent magnification and near-diffraction-limited resolution within an object distance range of 120mm-140mm. The infrared imaging is clear and sharp, clearly revealing the fine structure and features of objects, effectively reducing measurement errors for small objects. It is especially accurate and reliable for image-based size measurements. For example, in the working band of 8μm-12μm, with a magnification of 0.5, it can be matched with detectors with 640×512 pixels and a pixel size of 12μm.

[0047] 2) High stability: By reasonably setting positive and negative optical power to achieve optical calorimetry, the lens can maintain stable image quality in a temperature environment of -40℃ to +80℃, and the resolution is close to the diffraction limit; the object-side telecentric design ensures stable imaging magnification and can reduce image blurring or distortion caused by changes in object distance.

[0048] 3) Low cost: The lens shape is reasonably designed and all chalcogenide glass materials are used. Compared with traditional germanium silicon and other crystal materials, which are scarce and expensive, the procurement and processing costs are significantly reduced, effectively reducing production costs and further improving stability. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the structure of the telecentric infrared macro lens of the present invention;

[0050] Figure 2 This is the principal ray path diagram of the telecentric infrared macro lens of the present invention;

[0051] Figure 3 This is a dot diagram of Embodiment 1 of the present invention;

[0052] Figure 4 The field curvature and distortion diagrams are from Embodiment 1 of the present invention;

[0053] Figure 5 This is the MTF image of Embodiment 1 of the present invention at a distance of 120 mm from the object at room temperature;

[0054] Figure 6 This is the MTF image of Embodiment 1 of the present invention at a distance of 130 mm from the object at room temperature;

[0055] Figure 7 This is the MTF image of Embodiment 1 of the present invention at a distance of 140 mm from the object at room temperature;

[0056] Figure 8 This is the MTF chart of Embodiment 1 of the present invention at a distance of 130 mm from the object at -40°C;

[0057] Figure 9 This is the MTF chart of Embodiment 1 of the present invention at a distance of 130 mm from the object at +80°C.

[0058] Explanation of reference numerals in the attached diagram: L1, first lens; L2, second lens; L3, third lens; STO, aperture stop; L4, fourth lens; L5, fifth lens; N1, protective glass; IMA, focal plane. Detailed Implementation

[0059] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0060] It should be noted that the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application.

[0061] like Figures 1-2 As shown, a telecentric infrared macro lens includes a first lens L1, a second lens L2, a third lens L3, an aperture stop STO, a fourth lens L4, and a fifth lens L5 arranged sequentially along the optical axis from the object side to the image side. The third lens L3 is capable of focusing by moving along the optical axis.

[0062] The first lens L1 is a biconvex lens with positive optical power;

[0063] The second lens L2, the fourth lens L4, and the fifth lens L5 are all meniscus lenses with positive optical power and convex to the object side.

[0064] The third lens L3 is a meniscus lens with negative optical power and convex to the object side;

[0065] The object-centric telecentric infrared macro lens also meets the following conditions:

[0066] 0.75≤|f1 / f|≤0.85, 0.44≤|f2 / f|≤0.54, 0.2≤|f3 / f|≤0.3,

[0067] 0.3≤|f4 / f|≤0.4, 1.45≤|f5 / f|≤1.55;

[0068] Where f1 is the focal length of the first lens L1, f2 is the focal length of the second lens L2, f3 is the focal length of the third lens L3, f4 is the focal length of the fourth lens L4, f5 is the focal length of the fifth lens L5, and f is the effective focal length of the object-side telecentric infrared macro lens, in mm.

[0069] For ease of understanding, such as Figure 1 As shown, along the optical axis from left to right, the left side is the object side and the right side is the image side.

[0070] like Figure 2 As shown, by placing the aperture stop STO at the focal point of the front-end group (including the first lens L1, the second lens L2, and the third lens L3), the telecentric effect of the object side is achieved. By appropriately setting the lens shape, optical power, and focal length ratio, the telecentricity can be ensured to remain less than 0.1°. The light beam emitted from the object surface passes through the first lens L1, the second lens L2, the third lens L3, the aperture stop STO, the fourth lens L4, and the fifth lens L5 from left to right, and is then imaged onto the focal plane IMA, thus achieving macro detection imaging. "Object" represents the object surface.

[0071] In one embodiment, the object-side telecentric infrared macro lens also satisfies the following condition:

[0072] 175.5≤R1≤193.4, -605.2≤R2≤-562.4,

[0073] 70.6≤R3≤83.4, 535.3≤R4≤564.5,

[0074] 52.2≤R5≤63.1, 19.5≤R6≤24.2,

[0075] 10≤R7≤70, 26.5≤R8≤31.5

[0076] 48.6≤R9≤55.0, 422.5≤R10≤465.4;

[0077] Wherein, R1, R3, R5, R7, and R9 are the object-side radii of curvature of the first lens L1, second lens L2, third lens L3, fourth lens L4, and fifth lens L5, respectively; and R2, R4, R6, R8, and R10 are the image-side radii of curvature of the first lens L1, second lens L2, third lens L3, fourth lens L4, and fifth lens L5, respectively, in mm. By appropriately setting the curvature radii of each lens, it is helpful to improve image quality and imaging stability under different environments.

[0078] In one embodiment, the object-side telecentric infrared macro lens also satisfies the following condition:

[0079] 40≤A1≤45, 9.0≤A2≤12, 3.5≤A3≤6.6,

[0080] 13.5≤A4≤15.5, 6.5≤A5≤7.8;

[0081] Wherein, A1 is the air gap between the first lens L1 and the second lens L2, A2 is the air gap between the second lens L2 and the third lens L3, A3 is the air gap between the third lens L3 and the aperture stop STO, A4 is the air gap between the aperture stop STO and the fourth lens L4, and A5 is the air gap between the fourth lens L4 and the fifth lens L5, in mm.

[0082] In this embodiment, by reasonably setting the air gaps between the optical elements, and since the third lens L3 is a focusing group, the air gap A2 between the second lens L2 and the third lens L3 compensates for the air gap A3 between the third lens L3 and the aperture stop STO. Within the object distance range of 120mm-140mm, this embodiment preferably keeps the total length of A2 and A3 constant at 15.61mm, with 9.08mm ≤ A2 ≤ 11.8mm. By adjusting the position of the third lens L3, focusing can be achieved at different object distances, thus obtaining a clear imaging effect within the 120mm to 140mm range. The adjustment of the third lens L3 can employ existing focusing structures well-known to those skilled in the art or can be designed according to actual needs.

[0083] In one embodiment, the object-side telecentric infrared macro lens also satisfies the following condition:

[0084] 7.5≤d1≤8.5, 7.0≤d2≤7.8, 5.0≤d3≤6.0,

[0085] 5.0≤d4≤6.0, 4.0≤d5≤5.2;

[0086] Wherein, d1 is the center thickness of the first lens L1, d2 is the center thickness of the second lens L2, d3 is the center thickness of the third lens L3, d4 is the center thickness of the fourth lens L4, and d5 is the center thickness of the fifth lens L5, in mm.

[0087] In one embodiment, the object-side and image-side mirrors of the first lens L1, the fourth lens L4, and the fifth lens L5 are all aspherical, the object-side mirrors of the second lens L2 and the third lens L3 are both aspherical, the image-side mirror of the second lens L2 is a diffraction surface, and the image-side mirror of the third lens L3 is a spherical surface.

[0088] In one embodiment, the aspherical surface satisfies the following expression:

[0089] + + +

[0090] In the formula, radial distance on an aspherical surface The sag of the position, For curvature, = 1 / R, where R is the radius of curvature of the corresponding mirror surface. The conic coefficient, , , These are higher-order aspheric coefficients;

[0091] The phase distribution of the diffraction plane satisfies the following expression:

[0092]

[0093] In the formula, The radial distance of the diffraction surface Phase of position, For diffraction orders, To normalize the radius, , is the phase coefficient of the diffraction surface.

[0094] In one embodiment, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 are all chalcogenide glass lenses.

[0095] The first lens L1, second lens L2, third lens L3, fourth lens L4, and fifth lens L5 are made of chalcogenide glass. Traditional infrared macro lenses use crystalline materials such as silicon and germanium, which, while having a certain transmittance in the infrared band, are relatively expensive and difficult to process, increasing manufacturing costs and processing time. Furthermore, their high refractive index easily leads to optical aberrations such as chromatic aberration and spherical aberration, significantly affecting image quality. In addition, their thermal and chemical stability is relatively poor, and their performance easily degrades in complex working environments, failing to meet the requirements for long-term stable use. In contrast, the telecentric infrared macro lens of this application, through a reasonable material selection and the use of all-chalcogenide glass lenses, possesses excellent infrared transmittance, low cost, low refractive index, and low dispersion characteristics, achieving improved optical performance, thermal stability, and chemical stability to meet the needs of different application scenarios.

[0096] In one embodiment, the object-side telecentric infrared macro lens also satisfies the following condition:

[0097] 2.4≤n1≤2.9, 2.5≤n2≤2.9, 2.2≤n3≤2.8,

[0098] 2.2≤n4≤2.8, 2.4≤n5≤2.9;

[0099] Wherein, n1 is the refractive index of the first lens L1, n2 is the refractive index of the second lens L2, n3 is the refractive index of the third lens L3, n4 is the refractive index of the fourth lens L4, and n5 is the refractive index of the fifth lens L5. The preferred refractive indices are those of the lenses at a wavelength of 10 μm.

[0100] In one embodiment, the working wavelength of the object-side telecentric infrared macro lens is 8μm-12μm, and the object distance is 120mm-140mm.

[0101] In one embodiment, the object-side telecentric infrared macro lens also satisfies the following condition:

[0102] 1.17≤TTL / f≤1.31, 95≤f≤105, 1:1.1≤F#≤1:1.3;

[0103] Where TTL is the total optical length of the object-side telecentric infrared macro lens, in mm; F# is the relative aperture of the object-side telecentric infrared macro lens.

[0104] Example 1:

[0105] like Figures 3-9As shown, the object-side telecentric infrared macro lens of this embodiment includes a first lens L1, a second lens L2, a third lens L3, an aperture stop STO, a fourth lens L4, a fifth lens L5, and a protective glass N1 arranged sequentially along the optical axis from the object side to the image side. The third lens L3 can be moved along the optical axis for focusing. The object-side and image-side mirror surfaces of the first lens L1, the fourth lens L4, and the fifth lens L5, as well as the object-side mirror surface of the second lens L2 and the third lens L3, are all aspherical. The image-side mirror surface of the second lens L2 is a diffraction surface based on an aspherical surface, and the image-side mirror surface of the third lens L3 is spherical. TTL / f=1.24, f=100mm. Optical parameters are shown in Tables 1 and 2.

[0106] Table 1

[0107]

[0108] Table 2

[0109]

[0110] In the table, S1, S3, S5, S7, S9, and S11 are the object-side mirrors of the first lens L1, the second lens L2, the third lens L3, the aperture stop STO, the fourth lens L4, the fifth lens L5, and the protective glass N1, respectively; and S2, S4, S6, S8, S10, and S12 are the image-side mirrors of the first lens L1, the second lens L2, the third lens L3, the aperture stop STO, the fourth lens L4, the fifth lens L5, and the protective glass N1, respectively.

[0111] In the phase distribution expression of the diffraction surface in this embodiment, =1, =-0.1663, =4.1274E-05, normalized radius =1.

[0112] Based on the data in the table above, the dot plot of the object-side telecentric infrared macro lens in this embodiment is as follows: Figure 3 As shown, the field curvature and distortion diagram are Figure 4 MTF plots for different object distances at room temperature are shown below. Figure 5 , Figure 6 , Figure 7 As shown, Figure 8 , Figure 9These correspond to MTF plots at -40℃ and +80℃ at an object distance of 130mm, respectively. In the dot plot, the root mean square diameter of the diffuse spot is smaller than the Airy disk diameter. In the MTF plot, the horizontal axis represents spatial frequency (SRF) in cycles per mm, and the vertical axis represents the modulation index (OTF). The MTF curves for all fields of view representing the meridional plane show that the MTF is close to the diffraction limit, enabling high-quality imaging at object distances of 120mm~140mm, and ensuring stable imaging at different object distances and temperatures. This object-side telecentric infrared macro lens operates in the 8μm-12μm band, has a magnification of 0.5, and can be used with detectors with 640×512 pixels and a pixel size of 12μm, exhibiting low distortion.

[0113] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0114] The embodiments described above are merely specific and detailed examples of the embodiments described in this application, and should not be construed as limiting the scope of the application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the appended claims.

Claims

1. A telecentric infrared macro lens, characterized in that: The system includes a first lens (L1), a second lens (L2), a third lens (L3), an aperture stop (STO), a fourth lens (L4), and a fifth lens (L5) arranged sequentially along the optical axis from the object side to the image side. The third lens (L3) is capable of focusing by moving along the optical axis. The first lens (L1) is a biconvex lens with positive optical power; The second lens (L2), the fourth lens (L4), and the fifth lens (L5) are all meniscus lenses with positive optical power and convex to the object side; The third lens (L3) is a meniscus lens with negative optical power and convex to the object side; The object-side telecentric infrared macro lens also meets the following conditions: 0.75≤|f1 / f|≤0.85, 0.44≤|f2 / f|≤0.54, 0.2≤|f3 / f|≤0.3, 0.3≤|f4 / f|≤0.4, 1.45≤|f5 / f|≤1.55; Wherein, f1 is the focal length of the first lens (L1), f2 is the focal length of the second lens (L2), f3 is the focal length of the third lens (L3), f4 is the focal length of the fourth lens (L4), f5 is the focal length of the fifth lens (L5), and f is the effective focal length of the object-side telecentric infrared macro lens, in mm.

2. The object-side telecentric infrared macro lens as described in claim 1, characterized in that: The object-side telecentric infrared macro lens also meets the following conditions: 175.5≤R1≤193.4, -605.2≤R2≤-562.4, 70.6≤R3≤83.4, 535.3≤R4≤564.5, 52.2≤R5≤63.1, 19.5≤R6≤24.2, 10≤R7≤70, 26.5≤R8≤31.5 48.6≤R9≤55.0, 422.5≤R10≤465.4; Wherein, R1, R3, R5, R7, and R9 are the radii of curvature of the object-side mirrors of the first lens (L1), the second lens (L2), the third lens (L3), the fourth lens (L4), and the fifth lens (L5), respectively, and R2, R4, R6, R8, and R10 are the radii of curvature of the image-side mirrors of the first lens (L1), the second lens (L2), the third lens (L3), the fourth lens (L4), and the fifth lens (L5), respectively, in mm.

3. The object-side telecentric infrared macro lens as described in claim 1, characterized in that: The object-side telecentric infrared macro lens also meets the following conditions: 40≤A1≤45, 9.0≤A2≤12, 3.5≤A3≤6.6, 13.5≤A4≤15.5, 6.5≤A5≤7.8; Wherein, A1 is the air gap between the first lens (L1) and the second lens (L2), A2 is the air gap between the second lens (L2) and the third lens (L3), A3 is the air gap between the third lens (L3) and the aperture stop (STO), A4 is the air gap between the aperture stop (STO) and the fourth lens (L4), and A5 is the air gap between the fourth lens (L4) and the fifth lens (L5), in mm.

4. The object-side telecentric infrared macro lens as described in claim 1, characterized in that: The object-side telecentric infrared macro lens also meets the following conditions: 7.5≤d1≤8.5, 7.0≤d2≤7.8, 5.0≤d3≤6.0, 5.0≤d4≤6.0, 4.0≤d5≤5.2; Wherein, d1 is the center thickness of the first lens (L1), d2 is the center thickness of the second lens (L2), d3 is the center thickness of the third lens (L3), d4 is the center thickness of the fourth lens (L4), and d5 is the center thickness of the fifth lens (L5), in mm.

5. The object-side telecentric infrared macro lens as described in claim 1, characterized in that: The object-side and image-side mirrors of the first lens (L1), the fourth lens (L4), and the fifth lens (L5) are all aspherical. The object-side mirrors of the second lens (L2) and the third lens (L3) are both aspherical. The image-side mirror of the second lens (L2) is a diffraction surface, and the image-side mirror of the third lens (L3) is a spherical surface.

6. The object-side telecentric infrared macro lens as described in claim 5, characterized in that: The aspherical surface satisfies the following expression: + + + In the formula, radial distance on an aspherical surface The sag of the position, For curvature, = 1 / R, where R is the radius of curvature of the corresponding mirror surface. The conic coefficient, , , These are higher-order aspheric coefficients; The phase distribution of the diffraction surface satisfies the following expression: In the formula, The radial distance of the diffraction surface Phase of position, For diffraction orders, To normalize the radius, , is the phase coefficient of the diffraction surface.

7. The object-side telecentric infrared macro lens as described in claim 1, characterized in that: The first lens (L1), the second lens (L2), the third lens (L3), the fourth lens (L4), and the fifth lens (L5) are all chalcogenide glass lenses.

8. The object-side telecentric infrared macro lens as described in claim 1, characterized in that: The object-side telecentric infrared macro lens also meets the following conditions: 2.4≤n1≤2.9, 2.5≤n2≤2.9, 2.2≤n3≤2.8, 2.2≤n4≤2.8, 2.4≤n5≤2.9; Wherein, n1 is the refractive index of the first lens (L1), n2 is the refractive index of the second lens (L2), n3 is the refractive index of the third lens (L3), n4 is the refractive index of the fourth lens (L4), and n5 is the refractive index of the fifth lens (L5).

9. The object-side telecentric infrared macro lens as described in claim 1, characterized in that: The working wavelength of the object-side telecentric infrared macro lens is 8μm-12μm, and the object distance is 120mm-140mm.

10. The object-side telecentric infrared macro lens as described in claim 1, characterized in that: The object-side telecentric infrared macro lens also meets the following conditions: 1.17≤TTL / f≤1.31, 95≤f≤105, 1:1.1≤F#≤1:1.3; Wherein, TTL is the total optical length of the object-side telecentric infrared macro lens, in mm; F# is the relative aperture of the object-side telecentric infrared macro lens.

Images