lens

Abstract

Provided is a lens. The optical assembly of the lens only comprises two positive meniscus lenses made of chalcogenide glass, which can reduce the aperture of the lens and simplify the structure, thereby reducing the corresponding cost and being suitable for large-scale industrial production. Since the two lenses constituting the optical assembly are abutted against the elastic connecting portion of the lens barrel, the stability of the connecting structure of the lens and the lens barrel is improved, the possibility of dislocation and separation of the lens and the lens barrel and damage of the lens under impact conditions is greatly reduced by buffering with the elastic connecting portion, thereby the impact resistance of the lens can be improved. The threaded connecting structure in the form of multi-start thread is adopted between the focusing ring and the lens barrel of the lens, so that the stability of the connecting structure of the lens barrel and the focusing ring is improved, and the possibility of jamming or dislocation of the focusing ring and the lens barrel under impact conditions due to impact is avoided, thereby the impact resistance of the lens can be further improved.

Description

Technical Field

[0001] This application relates to the field of optical components, and more specifically to a lens. Background Technology

[0002] Currently, infrared lenses have a wide range of applications, with infrared gun sights being a typical example. In the common designs of these lenses, the first lens element is made of germanium glass, and the optical components include at least three lenses. This results in a large aperture and complex structure, leading to higher costs. Furthermore, some lenses need to meet the requirements of specific working environments, thus requiring them to withstand certain impact conditions (e.g., a 1200g impact).

[0003] Therefore, how to ensure good shock resistance of the lens while achieving a low cost is an urgent problem to be solved. Summary of the Invention

[0004] This application is made in view of the aforementioned state of the prior art. The purpose of this application is to provide a lens that can achieve good shock resistance while maintaining a low cost.

[0005] This application provides a lens as follows:

[0006] The optical assembly consists of only two lenses: a first lens and a second lens. The first lens is a positive meniscus lens made of chalcogenide glass, and the second lens is a positive meniscus lens made of chalcogenide glass. The first lens and the second lens are arranged sequentially from the object side toward the image side at intervals along the extension direction of the optical axis of the lens.

[0007] The lens barrel has a first base, a first elastic buffer, a second base, and a second elastic buffer. The first base has a first annular groove and the first elastic buffer is housed in the first annular groove. The first lens is mounted on the first base and abuts against the first elastic buffer. The second base has a second annular groove and the second elastic buffer is housed in the second annular groove. The second lens is mounted on the second base and abuts against the second elastic buffer. The lens barrel has an external thread portion with a multi-start thread.

[0008] A focusing ring having an internal thread portion in the form of a multi-start thread, the internal thread portion being threadedly engaged with the external thread portion; and

[0009] A connector assembly for partially inserting the lens barrel, and the focusing ring is fitted onto the connector assembly and limited by the connector assembly in the extension direction of the optical axis.

[0010] In one alternative embodiment, the first annular groove has a radial opening that opens radially inward, and the first elastic buffer portion abuts against the outer peripheral surface of the first lens via the radial opening.

[0011] The second annular groove has an object-side opening that faces the object side, and the second elastic buffer portion abuts against the image-side end face of the outer periphery of the second lens via the object-side opening.

[0012] In another alternative embodiment, the lens barrel includes a main body portion and a protruding portion extending radially outward from the main body portion, wherein the external thread portion is formed on the outer peripheral surface of the protruding portion.

[0013] The focusing ring includes a ring body portion and a ring protrusion portion protruding radially inward from the ring body portion, wherein the internal thread portion is formed on the inner circumferential surface of the ring protrusion portion.

[0014] The connector assembly defines a limiting groove for limiting the annular protrusion in the extension direction of the optical axis, the bottom of the limiting groove having a through hole, through which one of the annular protrusion and the cylindrical protrusion passes and is threadedly engaged with the other.

[0015] In another alternative embodiment, the ring body protrudes from the ring protrusion toward the object side and the image side respectively, and the portions of the ring body on both sides of the ring protrusion are supported by the connecting seat assembly.

[0016] In another alternative embodiment, the connecting seat assembly includes a mounting cylinder and a connecting seat fixed to each other. The mounting cylinder includes a cylinder base, a first support, and a second support, all fixed to each other.

[0017] The first support portion is located on the object side relative to the tube base portion. The first support portion is fitted onto the lens tube from the radially outer side and supports the ring body portion from the radially inner side.

[0018] The second support portion is located on the image side relative to the lens barrel base portion. The second support portion is fitted onto the lens barrel from the radial outside and supports the connecting seat from the radial inside. A portion of the connecting seat is located between the second support portion and the focusing ring, such that the second support portion supports the focusing ring via the connecting seat.

[0019] In another alternative embodiment, the first lens is made of chalcogenide glass of type IRG202. The first lens includes a first surface and a second surface. The first surface is convex and faces the object side, and the radius of curvature of the first surface is 40 mm to 50 mm. The second surface is concave and faces the image side, and the radius of curvature of the second surface is 75 mm to 85 mm.

[0020] In another alternative embodiment, the second lens is made of chalcogenide glass of type IRG206. The second lens includes a third surface and a fourth surface. The third surface is convex and faces the object side, and the radius of curvature of the third surface is 15 mm to 25 mm. The fourth surface is concave and faces the image side, and the radius of curvature of the fourth surface is 15 mm to 25 mm.

[0021] In another alternative embodiment, at least one of the first surface, the second surface, the third surface, and the fourth surface is an aspherical surface, wherein the aspherical surface satisfies:

[0022]

[0023] Where z is the sag of a point on the aspherical surface along the optical axis, r is the shortest distance between the point and the optical axis, c is the radius of curvature at the vertex of the aspherical surface, k is the conic coefficient of the aspherical surface, and α i Let be the aspherical coefficients of the aspherical surface, i be the index of the polynomial terms in the aspherical surface, and N be the total number of polynomial terms in the aspherical surface.

[0024] In another alternative embodiment, the second surface is a diffraction surface, which satisfies the following:

[0025]

[0026] Where Φ is the phase of the diffraction surface, M is the diffraction order of the diffraction surface, and A i ρ represents the coefficients of each term in the diffraction surface, ρ represents the normalized radial aperture coordinates of the diffraction surface, i represents the index of the polynomial term in the diffraction surface, and N represents the total number of polynomial terms in the diffraction surface.

[0027] In another alternative embodiment, the total optical length of the lens is less than or equal to 62 mm, and the air gap between the first lens and the second lens in the direction of extension of the optical axis is 37.6 mm.

[0028] The lens has a focal length of 50mm, an F-number of 1.0, a field of view greater than or equal to 11.2°, an optical back focal length greater than or equal to 10mm, and an operating wavelength of 8μm to 12μm.

[0029] By adopting the above technical solution, this application provides a lens. The lens includes an optical assembly, a lens barrel, a focusing ring, and a connecting seat assembly assembled together. Specifically, the optical assembly includes only a first lens and a second lens. The first lens is a positive meniscus lens made of chalcogenide glass, and the second lens is a positive meniscus lens made of chalcogenide glass. The first and second lenses are arranged sequentially from the object side to the image side along the optical axis of the lens, spaced apart. The lens barrel has a first seat portion, a first elastic buffer portion, a second seat portion, and a second elastic buffer portion. The first seat portion forms a first annular groove, and the first elastic buffer portion is housed in the first annular groove. The first lens is mounted on the first seat portion and abuts against the first elastic buffer portion. The second seat portion forms a second annular groove, and the second elastic buffer portion is housed in the second annular groove. The second lens is mounted on the second seat portion and abuts against the second elastic buffer portion. The lens barrel has an external thread portion in the form of a multi-start thread. The focusing ring has an internal thread portion in the form of a multi-start thread, and the internal thread portion and the external thread portion are threadedly engaged. The connector assembly allows the lens barrel to be partially inserted and installed, and the focusing ring is fitted onto the connector assembly and is limited by the connector assembly in the direction of extension of the optical axis.

[0030] Thus, since the optical assembly consists of only two positive meniscus lenses made of chalcogenide glass (high transmittance), compared to lenses in the prior art that use lenses with a first lens made of germanium glass and include at least three lenses, the lens aperture can be reduced and the structure simplified, thereby lowering the corresponding cost and making it suitable for large-scale industrial production. Furthermore, since both lenses constituting the optical assembly abut against the elastic connection of the lens barrel, the stability of the lens-barrel connection structure is improved. The use of the elastic connection for buffering significantly reduces the possibility of lens misalignment and separation, as well as lens breakage, under impact conditions, thereby improving the lens's impact resistance. Moreover, the multi-threaded connection structure between the focusing ring and the lens barrel improves the stability of the connection structure between the lens barrel and the focusing ring, while avoiding the possibility of jamming or misalignment of the focusing ring and lens barrel under impact conditions, thereby further improving the lens's impact resistance.

[0031] It should be noted that the lens according to this application has passed the 1200g impact test, and the lens focal length is 50mm, which can be adapted to a long-wave infrared uncooled 640×512@12μm detector. Attached Figure Description

[0032] Figure 1 A cross-sectional schematic diagram of a lens according to an embodiment of this application is shown, including its central axis (collinear with the optical axis of the optical components).

[0033] Figure 2 It shows Figure 1A schematic diagram of the optical components of the lens, which also shows the flat glass that cooperates with the optical components.

[0034] Figure 3 It shows Figure 1 The optical modulation transfer function curve of the lens at 20℃.

[0035] Figure 4 It shows Figure 1 The optical modulation transfer function curve of the lens at -40℃.

[0036] Figure 5 It shows Figure 1 The optical modulation transfer function curve of the lens at 60℃.

[0037] Figure 6 It shows Figure 1 Scene curve diagram of the shot.

[0038] Figure 7 It shows Figure 1 The distortion of the lens in the image.

[0039] Figure 8 It shows Figure 1 The relative illumination diagram of the lens in the image.

[0040] Explanation of reference numerals in the attached figures

[0041] 1. First lens; S1. First surface; S2. Second surface;

[0042] 2. Second lens; S3. Third surface; S4. Fourth surface;

[0043] 3. Lens tube; 31. Tube body; 32. Tube protrusion; 32s. External thread; 33. First seat; 33c. First annular groove; 34. First elastic buffer; 35. Second seat; 35c. Second annular groove; 36. Second elastic buffer.

[0044] 4. Focusing ring; 41. Ring body; 411. First supported part; 412. Second supported part; 42. Ring protrusion; 42s. Internal thread part;

[0045] 5. Mounting cylinder; 51. Cylinder base; 52. First support part; 53. Second support part;

[0046] 6 connecting seats; 61 main body parts; 62 extension parts;

[0047] 7. Flat glass;

[0048] A is the optical axis; A1 is the object side; A2 is the image side. Detailed Implementation

[0049] Exemplary embodiments of this application are described below with reference to the accompanying drawings. It should be understood that these specific descriptions are for teaching those skilled in the art how to implement this application only, and are not intended to exhaust all possible methods of this application, nor to limit the scope of this application.

[0050] In this application, scientific notation is used to represent some numerical values. For example, -8.96e-7 represents -8.96 × 10⁻⁷. -7 Unless otherwise specified, "from one value to another" includes one value and another value itself, as well as any value in between.

[0051] The following description, in conjunction with the accompanying drawings, illustrates a lens according to an embodiment of this application.

[0052] According to one embodiment of this application, the lens can be an infrared gun sight lens. For example... Figure 1 As shown, the lens includes assembled optical components (including a first lens 1 and a second lens 2), a lens barrel 3, a focusing ring 4, and a connecting mount assembly (including a mounting tube 5 and a connecting mount 6).

[0053] In this embodiment, as Figure 1 As shown, the optical assembly includes only a first lens 1 and a second lens 2, therefore the lens's optical assembly includes only two lenses. The first lens 1 can be a positive meniscus lens, which may include a first surface S1 and a second surface S2. The first surface S1 can be convex and face the object side A1, with a radius of curvature of 40mm to 50mm. The second surface S2 can be concave and face the image side A2, with a radius of curvature of 75mm to 85mm. The second lens 2 can be a positive meniscus lens, which may include a third surface S3 and a fourth surface S4. The third surface S3 can be convex and face the object side A1, with a radius of curvature of 15mm to 25mm. The fourth surface S4 can be concave and face the image side A2, with a radius of curvature of 15mm to 25mm.

[0054] like Figure 1 and Figure 2As shown, the first lens 1, the second lens 2, and the flat glass 7 (which can be disposed in a device employing a lens according to an embodiment of this application) can be spaced apart in the extension direction of the optical axis A. Specifically, the first lens 1 can be located on the object side A1 of the second lens 2, and the flat glass 7 can be located on the image side A2 of the second lens 2, with a predetermined distance between them. The first lens 1 and the second lens 2 can be made of chalcogenide glass, for example, the first lens 1 can be made of chalcogenide glass of type (grade) IRG202, and the second lens 2 can be made of chalcogenide glass of type (grade) IRG206. Thus, compared with a lens using an optical assembly made of germanium glass, the lens aperture can be reduced and the structure simplified, thereby reducing the corresponding cost and making it suitable for large-scale industrial production. Since the first lens 1 is the first lens after the lens is assembled (the first lens through which external light passes after entering the lens), the first lens 1 has a greater thickness, which is beneficial to improving the structural strength of the first lens 1 and even the lens, thereby improving the impact resistance of the lens. The air gap between the first lens 1 and the second lens 2 along the extension direction of the optical axis A can be 37.6 mm. Furthermore, in this embodiment, the total optical length of the lens can be less than or equal to 62 mm, and the optical back focal length can be greater than or equal to 10 mm. The focal length of the lens can be 50 mm, the F-number can be 1.0, and the field of view can be greater than or equal to 11.2°. Additionally, the lens can be adapted to a detector with a resolution of 640×512, a pixel size of 12 μm, and an operating wavelength range of 8 μm to 12 μm.

[0055] The first lens 1 and the second lens 2 may include aspherical surfaces. Specifically, the first surface S1, the second surface S2, the third surface S3, and the fourth surface S4 may be aspherical surfaces, and the aforementioned aspherical surfaces satisfy the following conditions:

[0056]

[0057] Where z is the sag of a point on the aspherical surface along the optical axis A, r is the shortest distance between the point and the optical axis A, c is the radius of curvature at the vertex of the aspherical surface, k is the conic coefficient of the aspherical surface, and α i denoted as the aspherical coefficients, i is the index of the polynomial term in the aspherical surface, and N is the total number of polynomial terms in the aspherical surface.

[0058] For example, the first surface S1 can satisfy 40mm≤c≤50mm, k=0, α2=-8.962102e-7, α3=-2.700487e-10, α4=-6.869037e-12, α5=-5.303647e-15, α6=1.988985e-17, α7=-2.536248e-20;

[0059] The second surface S2 can satisfy 75mm≤c≤85mm, k=0, α2=-2.222979e-7, α3=-4.979792e-9, α4=-1.068456e-12, α5=-5.996767e-15, α6=2.614511e-18, α7=-1.428129e-21;

[0060] The third surface S3 can satisfy 15mm≤c≤25mm, k=0, α2=4.043854e-5, α3=5.680769e-7, α4=-1.166535e-8, α5=1.822643e-10, α6=-1.338016e-12, α7=4.244407e-15;

[0061] The fourth face S4 can satisfy 15mm≤c≤25mm, k=0, α2=8.204333e-5, α3=1.240016e-6, α4=-3.076725e-8, α5=7.239175e-10, α6=-7.938487e-12, α7=3.943524e-14.

[0062] In the above formula for aspherical surfaces, the coefficient α is not given. i It is 0.

[0063] The first lens 1 may include a diffraction surface. Specifically, the second surface S2 may be a diffraction surface, and the aforementioned diffraction surface can satisfy the following:

[0064]

[0065] Where Φ is the phase of the diffraction plane, M is the diffraction order of the diffraction plane, and A i Let ρ be the coefficient of each term in the diffraction plane, ρ be the normalized radial aperture coordinate of the diffraction plane, i be the index of the polynomial term in the diffraction plane, and N be the total number of polynomial terms in the diffraction plane. For example, the second plane S2 can satisfy M = 100, A1 = -1240.96, and A2 = 1716.38. In the above diffraction plane formula, the coefficient A is not given. i It is 0.

[0066] Reference Figures 3 to 5 It shows the optical modulation transfer function (MTF) curve of the lens. The horizontal axis represents spatial frequency, in lines pairs per millimeter (lp / mm). The vertical axis represents the coefficients of the optical transfer function (OTF).

[0067] Reference Figure 3It shows the meridional (T) and sagittal (S) modulation transfer function curves of the lens at 20°C with image plane heights of 0.0000 mm, 0.9840 mm, 1.9680 mm, 2.9520 mm, 3.9360 mm, and 4.9200 mm, and operating wavelengths from 8 μm to 12 μm, for 42 line pairs. From Figure 3 It can be seen that the meridional and sagittal modulation transfer functions of the central field of view (image plane height of 0.0000mm) are greater than 0.41, while the modulation transfer functions of the other fields of view are greater than 0.32. The lens has relatively high meridional and sagittal modulation transfer function curves, indicating that the lens has good image quality at room temperature.

[0068] Reference Figure 4 It shows the meridional (T) and sagittal (S) modulation transfer function curves of the lens at -40°C with image plane heights of 0.0000 mm, 0.9840 mm, 1.9680 mm, 2.9520 mm, 3.9360 mm, and 4.9200 mm, and operating wavelengths from 8 μm to 12 μm, under 42 line pairs. From Figure 4 It can be seen that the meridional and sagittal modulation transfer functions of the central field of view (image plane height of 0.0000mm) are greater than 0.40, while the modulation transfer functions of the other fields of view are greater than 0.31. The lens has relatively high meridional and sagittal modulation transfer function curves, indicating that the lens has good image quality at -40℃.

[0069] Reference Figure 5 It shows the meridional (T) and sagittal (S) modulation transfer function curves of the lens at 60°C with image plane heights of 0.0000mm, 0.9840mm, 1.9680mm, 2.9520mm, 3.9360mm, and 4.9200mm, and operating wavelengths from 8μm to 12μm, under 42 line pairs. From Figure 5 It can be seen that the meridional and sagittal modulation transfer functions of the central field of view (image plane height of 0.0000mm) are greater than 0.41, while the modulation transfer functions of the other fields of view are greater than 0.31. The lens has relatively high meridional and sagittal modulation transfer function curves, indicating that the lens has good image quality at 60℃.

[0070] Reference Figure 6 It shows the field curvature diagrams of the lens at operating wavelengths of 8.0000μm, 10.0000μm, and 12.0000μm. The horizontal axis represents the field curvature in mm, and the vertical axis represents the field of view. From... Figure 6 It can be seen that the meridional curvature and sagittal curvature of the lens are both controlled within the range of -0.1mm to 0.1mm.

[0071] Reference Figure 7 This diagram shows the lens distortion. The horizontal axis represents the percentage of distortion, and the vertical axis represents the field of view. From... Figure 7 As can be seen, the lens distortion is less than 1.6%, thus avoiding image distortion.

[0072] Reference Figure 8 This diagram shows the relative illumination of the lens. The horizontal axis represents the image plane height of the optical components, in mm. The vertical axis represents the normalized illuminance. From... Figure 8 It can be seen that the relative illuminance at the center of the lens is 1, with no energy loss. The relative illuminance at the edge of the lens is greater than 0.93. Therefore, the relative illuminance of the lens is greater than 0.93.

[0073] Thus, with the above configuration, the lens can achieve high-quality imaging using only two lenses (first lens 1 and second lens 2) and achieve passive, thermal optical imaging. This allows the lens to have a simpler structure, effectively reducing costs and making it suitable for large-scale industrial production. Furthermore, the smaller number of lenses results in a shorter overall length, lighter weight, and smaller size, improving portability.

[0074] In this embodiment, as Figure 1As shown, the lens barrel 3 includes an integrally formed main body 31 and a protruding part 32. The main body 31 is configured as a rotating body with a central axis, which is collinear with the optical axis A of the aforementioned optical component. The main body 31 internally defines a trumpet-shaped hollow space with an inner diameter that increases from the image side A2 towards the object side A1. An object-side opening and an image-side opening are formed on both sides of the hollow space. Near the object-side opening of the main body 31, the lens has a first seat 33 with a stepped structure. A first annular groove 33c is formed on the outer peripheral surface of the first seat 33, and the first annular groove 33c has a radial opening that opens radially inward. A first elastic buffer 34 can be formed in the first annular groove 33c by filling it with an adhesive material such as silicone. The first elastic buffer portion is housed in the first annular groove 33c. After the first lens 1 is mounted on the first seat 33 and engages with the stepped structure of the first seat 33, the outer peripheral surface of the first lens 1 abuts against the first elastic buffer portion 34. Furthermore, at the portion of the main body 31 near its image-side opening, the lens has a second seat 35 with a stepped structure. A second annular groove 35c is formed on the side of the second seat 35 facing the object side A1, and the second annular groove 35c has an object-side opening facing the object side A1. A second elastic buffer portion 36 can be formed in the second annular groove 35c by filling it with an adhesive material such as silicone. The second elastic buffer portion 36 is housed in the second annular groove 35c. After the second lens 2 is mounted on the second seat 35 and engages with the stepped structure of the second seat 35, the outer peripheral surface of the second lens 2 facing the image side A2 abuts against the second elastic buffer portion 36. Since both lenses constituting the optical assembly abut against the elastic connection portion of the lens barrel 3, the stability of the connection structure between the lens and the lens barrel 3 is improved. Furthermore, the elastic connection portion significantly reduces the possibility of misalignment and separation of the lens and the lens barrel 3, as well as lens breakage, under impact conditions, thereby improving the lens's impact resistance. In addition, the outer peripheral surface of the barrel body 31 has multiple stepped structures for mounting the connecting seat assembly. The barrel protrusion 32 protrudes radially outward from the portion of the outer peripheral surface of the barrel body 31 near the image-side opening, and the outer peripheral surface of the barrel protrusion 32 has an external thread 32s in the form of a multi-start thread (e.g., a double-start thread).

[0075] In this embodiment, as Figure 1As shown, the focusing ring 4 includes an integrally formed ring body portion 41 and a ring protrusion 42. The ring body portion 41 is formed into a hollow annular shape and is fitted radially outward onto the mounting sleeve 5 of the connecting seat assembly, and is arranged coaxially with the lens barrel 3. The ring protrusion 42 protrudes radially inward from the axial central portion of the ring body portion 41, thereby giving the ring body portion 41 a first supported portion 411 and a second supported portion 412 protruding from the ring protrusion 42 toward the object side A1 and the image side A2, respectively. The first supported portion 411 is supported by the mounting sleeve 5 of the connecting seat assembly, and the second supported portion 412 is supported by the mounting sleeve 5 of the connecting seat assembly via the connecting seat 6. The inner circumferential surface of the annular protrusion 42 has an internal thread 42s formed in the form of a multi-start thread (e.g., a double-start thread). This internal thread 42s is threadedly engaged with the external thread 32s. Thus, by twisting the focusing ring 4, the focusing ring 4 can be rotated reciprocally within a predetermined range, thereby driving the lens barrel 3 to reciprocate in the extension direction of the optical axis A, achieving the focusing function. It should be noted that a limiting mechanism to prevent the lens barrel 3 from rotating can be provided on the connecting seat assembly, or the rotation of the lens barrel 3 can be limited by the friction between the connecting seat assembly and the lens barrel 3. This ensures that the lens barrel 3, driven by the focusing ring 4, only reciprocates in the extension direction of the optical axis A, and does not rotate with the focusing ring 4. Because the focusing ring 4 and the lens barrel 3 use a multi-start threaded connection structure, the stability of the connection structure between the lens barrel 3 and the focusing ring 4 is improved, while avoiding the possibility of jamming or misalignment of the focusing ring 4 and the lens barrel 3 under impact conditions, thereby further improving the lens's impact resistance.

[0076] In this embodiment, as Figure 1As shown, the connecting seat assembly is coaxially arranged with the lens barrel 3 and allows the lens barrel 3 to be partially inserted and installed. The connecting seat assembly is also used to connect to a device using the lens of this application. The connecting seat assembly includes a mounting cylinder 5 and a connecting seat 6 fixed to each other. Specifically, the mounting cylinder 5 includes an integrally formed cylinder base portion 51, a first support portion 52, and a second support portion 53. The cylinder base portion 51 is formed in a cylindrical shape and has an arc-shaped through hole through which the cylinder protrusion 32 of the lens barrel 3 passes. The arc-shaped through hole extends radially through the cylinder base portion 51 and extends a certain length circumferentially. The circumferential length of the arc-shaped through hole is configured so as not to affect the structural strength of the mounting cylinder 5 and to ensure that the lens barrel 3 can rotate within a sufficient range. The first support portion 52 is located on the object side A1 relative to the cylinder base portion 51 and is fitted radially outward onto the cylinder body portion 31 of the lens barrel 3. Furthermore, the first support portion 52 directly supports the first supported portion 411 of the ring body portion 41 of the focusing ring 4 from the radially inward side. The second support portion 53 is located on the image side A2 relative to the barrel base portion 51 and is fitted onto the barrel body portion 31 of the lens barrel 3 from the radially outward side. The second support portion 53 directly supports the seat extension portion 62 of the connecting seat 6 from the radially inward side, and the seat extension portion 62 directly supports the second supported portion 412 of the focusing ring 4 from the radially inward side, thereby enabling the second support portion 53 to support the second supported portion 412 of the focusing ring 4 via the connecting seat 6. The connecting seat 6 includes a seat body portion 61 located on the image side A2 of the mounting barrel 5, and the seat body portion 61 may form an interface for connection with the aforementioned device. The seat extension portion 62 extends from the seat body portion 61 toward the object side A1 between the focusing ring 4 and the mounting barrel 5. In this way, on the one hand, the first support portion 52 of the mounting cylinder 5 and the seat extension portion 62 of the connecting seat 6 define a limiting groove that mates with the annular protrusion 42, thereby limiting the annular protrusion 42 of the focusing ring 4 in the extending direction of the optical axis A; on the other hand, the arc-shaped through hole (the arc-shaped through hole formed at the bottom of the limiting groove) of the cylinder base portion 51 of the mounting cylinder 5 circumferentially limits the barrel protrusion 32 of the lens barrel 3. Due to the above-described mounting structure of the connecting seat assembly with the lens barrel 3 and the focusing ring 4, the structural stability of the entire lens can be further improved, thereby further improving the impact resistance of the lens.

[0077] Furthermore, in this embodiment, sealing rings can be provided at the surfaces where the lens barrel 3 and the mounting barrel 5 abut against each other, as well as at the surfaces where the mounting barrel 5 and the focusing ring 4 abut against each other. The sealing rings can not only seal the gaps between these surfaces to prevent foreign objects from entering the lens through these gaps, but also further improve the lens's impact resistance by utilizing the elasticity of these sealing rings themselves.

[0078] It should be understood that the above embodiments are merely exemplary and are not intended to limit this application. Those skilled in the art can make various modifications and changes to the above embodiments under the teachings of this application without departing from the scope of this application. The technical solutions of this application are further described below.

[0079] i. The first surface S1, the second surface S2, the third surface S3, and the fourth surface S4 are not limited to being aspherical surfaces. In the optional schemes, at least one of them is an aspherical surface.

[0080] ii. The spacing between the lenses of the lens is not limited to being filled with air; it can be filled with any possible gas.

[0081] iii. The radius of curvature of the first surface S1 is not limited to 40mm or 50mm. For example, in optional schemes, it can also be 41mm, 43mm, 46mm or 49mm, etc.

[0082] The radius of curvature of the second surface S2 is not limited to 75mm or 85mm. For example, in optional schemes, it can also be 76mm, 79mm, 81mm or 84mm, etc.

[0083] The radius of curvature of the third surface S3 is not limited to 15mm or 25mm. For example, in optional schemes, it can also be 17mm, 19mm, 20mm or 23mm, etc.

[0084] The radius of curvature of the fourth surface S4 is not limited to 15mm or 25mm. For example, in optional schemes, it can also be 17mm, 18mm, 21mm or 24mm, etc.

[0085] iv. In an alternative embodiment, the annular protrusion 42 of the focusing ring 4 can be inserted into the arc-shaped hole passing through the mounting cylinder 5 to achieve threaded engagement with the cylinder protrusion 32. It is understood that it is sufficient for either the annular protrusion 42 or the cylinder protrusion 32 to pass through the through hole and threadedly engage with the other.

Claims

1. A lens, characterized in that, include: The optical assembly consists of only two lenses: a first lens (1) and a second lens (2). The first lens (1) is a positive meniscus lens made of chalcogenide glass, and the second lens (2) is a positive meniscus lens made of chalcogenide glass. The first lens (1) and the second lens (2) are arranged sequentially from the object side (A1) toward the image side (A2) at intervals along the extension direction of the optical axis (A) of the lens. The lens barrel (3) has a first seat (33), a first elastic buffer (34), a second seat (35), and a second elastic buffer (36). The first seat (33) has a first annular groove (33c) and the first elastic buffer (34) is housed in the first annular groove (33c). The first lens (1) is mounted on the first seat (33) and abuts against the first elastic buffer (34). The second seat (35) has a second annular groove (35c) and the second elastic buffer (36) is housed in the second annular groove (35c). The second lens (2) is mounted on the second seat (35) and abuts against the second elastic buffer (36). The lens barrel (3) has an external thread (32s) in the form of a multi-start thread. The focusing ring (4) has an internal thread portion (42s) in the form of a multi-start thread, which is threadedly engaged with the external thread portion (32s); and Connector assemblies (5, 6) are provided for partial insertion and installation of the lens barrel (3), and the focusing ring (4) is fitted onto the connector assemblies (5, 6) and limited by the connector assemblies in the extension direction of the optical axis (A).

2. The lens according to claim 1, characterized in that, The first annular groove (33c) has a radial opening that opens radially inward, and the first elastic buffer portion (34) abuts against the outer peripheral surface of the first lens (1) through the radial opening. The second annular groove (35c) is formed with an object-side opening that opens toward the object side (A1), and the second elastic buffer portion (36) abuts against the image-side end face of the outer periphery of the second lens (2) via the object-side opening.

3. The lens according to claim 1, characterized in that, The lens barrel (3) includes a barrel body portion (31) and a barrel protrusion portion (32) that protrudes radially outward from the barrel body portion (31), and the external thread portion (32s) is formed on the outer peripheral surface of the barrel protrusion portion (32). The focusing ring (4) includes a ring body portion (41) and a ring protrusion portion (42) protruding radially inward from the ring body portion (41), wherein the internal thread portion (42s) is formed on the inner circumferential surface of the ring protrusion portion (42). The connecting seat assembly (5, 6) defines a limiting groove for limiting the annular protrusion (42) in the extension direction of the optical axis (A), the bottom of the limiting groove having a through hole, one of the annular protrusion (42) and the cylindrical protrusion (32) passing through the through hole and threadedly engaging with the other.

4. The lens according to claim 3, characterized in that, The ring body (41) protrudes from the ring protrusion (42) toward the object side (A1) and the image side (A2) respectively, and the portions of the ring body (41) located on both sides of the ring protrusion (42) are supported by the connecting seat assembly (5, 6).

5. The lens according to claim 4, characterized in that, The connecting seat assembly (5, 6) includes a mounting cylinder (5) and a connecting seat (6) fixed to each other. The mounting cylinder (5) includes a cylinder base (51), a first support (52), and a second support (53) fixed to each other. The first support portion (52) is located on the object side (A1) relative to the tube base portion (51). The first support portion (52) is fitted onto the lens tube (3) from the radially outer side and supports the ring body portion (41) from the radially inner side. The second support (53) is located on the image side (A2) relative to the lens barrel base (51). The second support (53) is fitted onto the lens barrel (3) from the radial outside and supports the connecting seat (6) from the radial inside. A portion of the connecting seat (6) is located between the second support (53) and the focusing ring (4), such that the second support (53) supports the focusing ring (4) via the connecting seat (6).

6. The lens according to any one of claims 1 to 5, characterized in that, The first lens (1) is made of chalcogenide glass of type IRG202. The first lens (1) includes a first surface (S1) and a second surface (S2). The first surface (S1) is convex and faces the object side (A1). The radius of curvature of the first surface (S1) is 40 mm to 50 mm. The second surface (S2) is concave and faces the image side (A2). The radius of curvature of the second surface (S2) is 75 mm to 85 mm.

7. The lens according to claim 6, characterized in that, The second lens (2) is made of chalcogenide glass of type IRG206. The second lens (2) includes a third surface (S3) and a fourth surface (S4). The third surface (S3) is convex and faces the object side (A1). The radius of curvature of the third surface (S3) is 15mm to 25mm. The fourth surface (S4) is concave and faces the image side (A2). The radius of curvature of the fourth surface (S4) is 15mm to 25mm.

8. The lens according to claim 7, characterized in that, At least one of the first surface (S1), the second surface (S2), the third surface (S3), and the fourth surface (S4) is an aspherical surface, and the aspherical surface satisfies: Where z is the sag of a point on the aspherical surface along the optical axis (A), r is the shortest distance between the point and the optical axis (A), c is the radius of curvature at the vertex of the aspherical surface, k is the conic coefficient of the aspherical surface, and α i Let be the aspherical coefficients of the aspherical surface, i be the index of the polynomial terms in the aspherical surface, and N be the total number of polynomial terms in the aspherical surface.

9. The lens according to claim 7, characterized in that, The second surface (S2) is a diffraction surface, and the diffraction surface satisfies: Where Φ is the phase of the diffraction surface, M is the diffraction order of the diffraction surface, and A i ρ represents the coefficients of each term in the diffraction surface, ρ represents the normalized radial aperture coordinates of the diffraction surface, i represents the index of the polynomial term in the diffraction surface, and N represents the total number of polynomial terms in the diffraction surface.

10. The lens according to any one of claims 1 to 5, characterized in that, The total optical length of the lens is less than or equal to 62 mm, and the air gap between the first lens (1) and the second lens (2) in the extension direction of the optical axis (A) is 37.6 mm. The lens has a focal length of 50mm, an F-number of 1.0, a field of view greater than or equal to 11.2°, an optical back focal length greater than or equal to 10mm, and an operating wavelength of 8μm to 12μm.

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